Minutes of the 135th Protection Committee Meeting (PCM) of ...

Minutes of the 135th PCM held on 26.02.2019 at WRPC Mumbai

Minutes of the 135th Protection Committee Meeting (PCM)

of WRPC held on 26.02.2019 at WRPC Mumbai.

The 135th meeting of Protection sub-Committee was held on 26thFebruary, 2019 at WRPC Mumbai. The list of participants enclosed at Annexure-I. Member Secretary (MS), WRPC welcomed all the participants of the 135th PCM. He informed that occurrences for the period from 01stOctober 2018 to 31st December 2018 will be discussed in this meeting (135thPCM). The 134th PCM was held in the month of November 2018. He informed that the 8thNPC (National Power Committee) meeting was held on 30th November 2018 at Guwahati and main issues discussed in the meeting are as follows;

(i) Revising the frequency settings of AUFLS Scheme: It was agreed by all the members that the existing stage-I, stage-II, stage-III and stage-IV frequency setting of 49.2Hz, 49.0Hz, 48.8Hz and 48.6Hzbe raised to 49.4Hz, 49.2Hz, 49.0Hz and 48.8Hz respectively. As regards to the quantum it was decided that the matter would be studied and the work would be entrusted to consultant. NRPC would co-ordinate with the consultant and the recommendations of the consultant would be put up in the 9thNPC meeting.

(ii) Disturbances: Analysis of the disturbances be done regularly and recommendations to avoid the recurrences of disturbances be submitted to NPC regularly.

(iii) He further informed that the frequency of PCM meetings is required to be increased as being done in some RPCs. It has been observed that the seriousness in analyzing the old disturbances is lost if the same is discussed /analyzed after say 2-3 months.

The 37th WRPC meeting was held in December 2018 wherein various important issues like non submission of protection audit compliance, Mumbai Islanding Scheme, frequent tripping at HVDC Champa, formation of 3rd party protection audit teams in WR, Implementation of WAMS and SPS of Agra-Gwalior was discussed.

After his opening remarks, he asked Superintending Engineer (Protection), WRPC to take up agenda items for discussion. Shri. J.K.Rathod, Superintending Engineer (Protection), WRPC welcomed all participants of the meeting and took up the agenda items for discussions.


Item No. 1:Confirmation of Minutes of the 134th PCM

The 134th meeting of protection sub-committee was held on 20thNovember 2018 at WRPC Mumbai. The Minutes of Meeting (MoM) was circulated vide letter WRPC/Protection/ PCM/Minutes/2018/12667 dated 29.11.2018. No comments were received on the MoM. The sub-Committee confirmed the MoM of the 134th PCM without modification.

Item No. 2:Grid Incidences(GI)/Grid Disturbances(GD)

2A. Gujarat system 2A.1. Substation: 400 kV Mansar Date & time: 16.10.2018 at 07:01 hrs and 07:50 hrs. Event Category: GI-2

2A.1.1: Event Summary On 16.10.2018 at 07.01 hrs there was a grid incidence at 400 kV

Mansars/s. 400 kV Mansar Bus 1 and associated elements tripped on Bus bar

protection operation at 07:01 Hrs on Y phase fault insulator flashover. 400 kV Mansar Bus 2 and associated elements tripped on Bus bar

protection operation at 07:50 Hrs on Y phase fault insulator flashover. Tripping’s observed are as follows:

o 400/220 kV 315 MVA Mansar ICT 1 o 400 kV Mansar Bus coupler o 400 kV Mansar-Bhachau o 400 kV Mansar-Chorania o 400/220 kV 315 MVA Mansar ICT 2

2A.1.2 : Discussion in 135th PCM GETCO representative gave a brief on the disturbance as follows;

The bus position of the 400KV feeders / transformers at the time of occurrence was as under: 400KV Bus coupler breaker was “ON”. 400KV Bus Reactor breaker was “OFF”. 400KV Transfer Bus coupler breaker was “OFF”.


a) Sequence of occurrence: At 400KV Mansar substation on 16-10-2018, 07:00Hrs 400KV Bus-A

tripped due to flashover of BUS-A Y Phase pilot string insulator connecting to earth switch. The bus differential protection Zone A operated leading to tripping of all bays connected with 400KV Bus A with 400KV Bus Coupler.

Single line diagram of the substation and fault location for Bus A fault as follows:-

After tripping of BUS-A at 07:00 hrs, at 07:49 hrs 400KV Bus-B tripped due to flashover of 400KV BUS-B Flyover Y Phase pilot string insulator of 400KV ICT-2 and bus differential protection Zone B operated leading to tripping of all bays connected with 400KV Bus A.

Single line diagram of the substation and fault location for Bus B fault as follows:-


400 KV Mansar substation: BUS-A(Zone-1) Y Phase Fault: Differential current of around 12 KA as shown in the DR.

BUS-B( Zone-2 ) Y Phase Fault: Differential current recorded was

around 6.7 KA as shown in DR;

b) Failure Equipment detail and last maintenance carried out: -

Details of the BUS-A Y Phase pilot string connecting to earth switch:

Make: IP INDIA Type: 120 KN

Batch. No.: 12-2012 Last maintenance of the BUS-A Y Phase pilot string connecting

to earth switch was carried out on 09-08-2018andthe porcelain insulating parts were cleaned with cotton cloth


Details of the ICT-2 BUS-B Flyover Y-Phase pilot string:

Make: IP INDIA Type: 120 KN

Batch: 10-2012 Last maintenance of the BUS-A Y Phase pilot string connecting

to earth switch was carried out on24-07-20182018andthe porcelain insulating parts were cleaned with cotton cloth.

c) Action Taken: After washing of ICT-2 flyover pilot string of all the three phases; 400

kV Choraniya line was charged on 400KV BUS-B, then 400 kV Bhachau line was charged on same BUS-B.

After washing of all three-phase pilot string connecting to earth switch of 400 kV BUS-A; 400KV bus coupler was charged and hence BUS-A was charged then 315 MVA 400/220 kV ICT-1 & 2.

All bays connected with 400KV Bus-A and Bus-B taken in service. The Event report is enclosed as Annexure 2A.1. d) Committee observed the following:

From the DR of central unit of bus bar it is seen that, on 16-10-2018 at 07:00Hrs 400KV Bus-A tripped due to flashover of BUS-A Y Phase pilot string insulator connecting to earth switch. The differential current in Y-phase of central unit of Bus bar protection scheme was 12KA, Bus-A cleared in 38ms.

After Bus Zone A fault, at 07:49 hrs 400KV Bus-B tripped due to flashover of 400KV BUS-B Flyover Y Phase pilot string insulator of 400KV ICT-2. The differential current in Y-phase of central unit of Bus bar protection scheme was 6.7 KA, Bus-A cleared in 48ms.

Alstom make Micom P741/743 Numerical bus bar scheme operated correctly.

GETCO representative informed that the S/S is surrounded by salt mills and the salt dust from the mills is carried to S/S by wind and the salt dust gets deposited on the insulators, leading to failure of Insulators.

MS suggested to ascertain why the pilot strings are failing and whether there is any issue related to jumper length and whether regular cleaning of the insulators is being done, if so then frequency needs to be increased. Also the creepage should be highest in the saline area, the same should be checked by GETCO.

PGCIL representative informed that the suspension insulator parts are more prone to salt deposits and they are using polymer insulators.

GETCO representative informed that the jumper length is around 7-8 mtrs and insulators manufacture batch is2012. He further informed that they have planned to replace the insulators with Silicon Rubber Insulators.

After discussion, PCM suggested to increase the frequency of insulator cleaning if necessary.


2A.2. Substation: 400/220 kV Mansar Date & time: 18.10.2018 at 6:31 hrs and 07:15 hrs. Event Category: GI-2

2A.2.1: Event Summary

On 18.10.2018 at 06.31 hrs there was a grid incidence at 400 kV Mansar s/s.

400 kV Mansar Bus 1 and associated elements tripped on Bus bar protection operation at 06:31 Hrs on Y phase fault insulator flashover

400 kV Mansar Bus 2 and associated elements tripped on Bus bar protection operation at 07:15 Hrs on Y phase fault insulator flashover.

Trippings observed are as follows: o 400/220 kV 315 MVA Mansar ICT 1 o 400 kV Mansar Bus coupler o 400 kV Mansar-Bachau o 400 kV 80 MVAR Mansar Bus reactor o 400 kV Mansar-Chorania o 400/220 kV 315 MVA Mansar ICT 2

2A.2.2: Discussion in 135thPCM GETCO representative gave a brief on the disturbance as below:

The bus position of the 400KV feeders / transformers at the time of occurrence was as under: 400KV Bus coupler breaker was “ON”. 400KV Bus Reactor breaker was “On”. 400KV Transfer Bus coupler breaker was “OFF”.

400KV BUS A 1) 400/220 kV, 315MVA ICT no.1 2) 400 kV Bhachau(Bhimasar PGCIL) line 3) 400 kV Bus reactor

400KV BUS B 1) 400/220KV, 315MVA ICT no.2 2) 400KV Chorania LINE


tripped due flashover of 400KV BUS-A flyover bus Y Phase pilot string insulator of 400KV ICT-1. So, bus differential protection Zone A operated leading to tripping of all bays connected with 400KV Bus A with 400KV Bus Coupler.

After tripping of BUS-A at 06:30 hrs, at 07:15 hrs 400KV Bus-B tripped

due to flashover of 400KV BUS-B Y Phase pilot string connecting to earth switch. So, bus differential protection Zone B operated leading to tripping of all bays connected with 400KV Bus B.

Single line diagram of the substation and fault location for both Bus A fault as follows: -


Single line diagram of the substation and fault location for both Bus B

fault as follows: - 1)

b) Failure Equipment detail and last maintenance carried out: - Brief name plate details of ICT-1 BUS-A Flyover Y-Phase pilot string:

Make: IP INDIA Type: 120 KN Batch. No.: 12-2012


Last maintenance of the ICT-1 BUS-A Flyover Y-Phase pilot string was carried out on 09-08-2018 and the porcelain insulating parts were cleaned with cotton cloth

Brief name plate details of the BUS-B Y Phase pilot string connecting to

earth switch: Make: AC INDIA Type: 120 KN Batch: 06-2012

Last maintenance of the ICT-1 BUS-A Flyover Y-Phase pilot string was carried out on 09-08-2018 and the porcelain insulating parts were cleaned with cotton cloth

400 KV Mansar substation: BUS-A( Zone-1) Y Phase Fault:

Differential current about 12 KA.

BUS-B( Zone-2 ) Y Phase Fault: Differential current about 6.7 KA

The Event report is enclosed as Annexure 2A.2.


c) Action Taken:

After replacement of BUS-B Y Phase pilot string connecting to earth switch and After Cloth cleaning of all three-phase pilot string connecting to earth switch of 400 kV BUS-A & B, 400 kV choraniya line was charged and hence 400KV BUS-A was charged.

BUS-B was charged through 400KV bus coupler and then 315 MVA 400/220 kV ICT-2 and 400 kV bhachau line charged.

ICT-1 was charged after its flyover bus string maintenance work on dtd 19-10-18 at 20:05Hrs

d) Committee observed the following:

(i) From the DR of Central Unit of bus bar it is seen that, At 6:30 Bus Zone A protection operated due to flashover of 400KV BUS-A flyover bus Y Phase pilot string insulator of 400KV ICT-1. The differential current in Y-phase of central unit of Bus bar protection scheme was 12KA, Bus –A cleared in 45ms.

(ii) After Zone A fault in Bus, at 7:15 hrs Bus Zone –B protection operated due to flashover of 400KV BUS-B Y Phase pilot string connecting to earth switch. The differential current in Y-phase of central unit of Bus bar protection scheme was 6.7 KA, Bus-B cleared in 36ms.

(iii) Alstom make Micom P741/743 Numerical bus bar scheme operated correctly.

(iv) Again on 16.10.2018 both the buses tripped on insulator flashover. Also, repeated trippings were observed at Mansar S/S in previous months.

(v) MS WRPC observed that in most of the cases Y phase is involved. He suggested that the frequency of the hotline washing be increased in saline and polluted areas. He further enquired whether arcing horn is provided on the gantry side.

(vi) GETCO representative informed that HOT/COLD line washing of yard equipment was being carried out once in 3 months and in future they will carry out hot line washing every month to prevent such occurrences. He further informed that the failed pilot string insulators have been replaced with SRI’s (Slicone Rubber Insulators) and there is no arcing horn on gantry side.

(vii) GETCO representative further informed that they have planned to replace the insulators with Silicon Rubber Insulators.

After discussion, PCM suggested to increase the frequency of insulator cleaning if necessary.


2A.3. Substation: 220 kV Kosamba Date & time: 18.11.2018 at 07:35 hrs. Event Category: GI-1

2A.3. 1:Event Summary: On 18.11.2018 at 07.35 hrs there was a grid incidence at 220 kV

Kosamba s/s.

Due to Bus fault at 220 kV Kosamba substation, 220 kV Bus 1 and 2 tripped along with the connected elements on Bus bar protection operation.

Trippings observed are as follows: o 220 kV Kosamba-Kim D/C o 220 kV Kosamba-Jagadia D/C o 220 kV Kosamba-Mota o 220 kV Kosamba-Suva o 220 kV Kosamba-Vav o 220 kV Kosamba-Gavasad o 220 kV Kosamba-GSEG 2 o 220 kV Kosamba-Ichhapur o 400/220 kV 315 MVA ICTs 1,2,3&4 o 220/66 kV 100 MVA ICTs 1&2

2A.3.2: Discussion in 135th PCM GETCO representative gave a brief on the disturbance as follows;

Bus position of 220 KV feeders / transformers at the time of occurrence was as under. 220 KV Bus coupler breaker was “ON”. 220 kV TBC was “OFF”.

220 KV BUS A 1 220/66KV 100 MVA TR-1 2 220 KV Zagadiya-1 3 220 KV Gavasad 4 220 KV GSEG 5 220 KV Mota 6 400/220 KV 315 MVA ICT-3 7 220 KV Kim-2 8 400/220 KV 315 MVA ICT-1

220 KV BUS B 1 220/66 KV 100 MVA TR-2 2 220 KV Zagadiya-2 3 220 KV Suva 4 220 KV Ichhapore 5 220 KV Vav 6 400/220 KV 315 MVA ICT-2 7 220 KV Kim-1 8 400/220 KV 500 MVA ICT-4

a) Sequence/cause of occurrence:

On 18-11-2018 at 07:35:17 Hrs, Main -1 & Main-2 distance relay of 220 KV Kosamba-Ichhapore line was operated in B-Ph to earth fault after auto reclose operation of B-phase. However, B-ph. pole did not trip.

During auto reclose cycle of previous fault i.e. After 445 ms of 1st fault again Y to B Phase to phase fault detected by distance relay. During this time, R and Y phase pole of breaker get opened but B-phase pole did not tripped/opened. Due to non-tripping of B-phase breaker pole


and fault current persist in B-phase leads to local breaker backup protection (LBB) operation given by Siemens make 7SA522 Main- 1 distance relay as well as Siemens make 7SS52 Bus-bar protection scheme.

As LBB operated, all elements connected to Bus B tripped including bus coupler. Simultaneously, tripping command issued to all elements connected to Bus-A by Bus bar protection scheme due to wrong/invalid status of Isolator 89B of 220/66 100MVA TR-1 in Bus bar unit (BU). Thus, bus bar protection scheme has considered as single node for both bus and tripping command issued to both Bus-A & B. It has caused 220 KV system zero power at 400 KV Kosamba.

From DR analysis and Trip log of distance relay it is seen that at 7:35:17:666 relay detects B-phase to Ground Forward Zone-1 fault and so that auto-reclose cycle has initiated. Fault current was about 6.6KA. After 445ms of 1st fault again Y to B Phase-Phase zone-1 fault detected and 86A and 86B relay operated. This 2nd fault occurred with-in Pole dead time of Auto-reclose cycle of previous fault. Fault current of 2nd fault was about 11.6KA.

Due to this tripping line fault should be cleared by 220 KV Kosamba-Ichhapore line breaker but as B-phase pole of breaker did not open due to defective 52cx auxiliary contactor and loose tripping wiring on TB in C&R panel of Ichhapore line.

As fault did not clear and current persist in B-phase of 220 KV Ichhapore line, LBB(CBF) protection activated by below two different schemes.

1) LBB operation with internal Initiation at Main-1 7SA522 relay. 2) LBB operation with De-Centralized Bus bar Siemens make 7SS52

Scheme

Out of above two schemes, first one which internal LBB by Main-1-line distance relay operated correctly and It cleared Bus-B and Bus coupler by hard wired LBB bus scheme.

While second LBB scheme in bus bar protection 7SS52 has given trip to both Bus –A and Bus-B. This malfunction occurred because bus bar protection has considered two different bus zones A & B as single zone due to invalid status of isolator 89B in bus bar unit(87BB) of 220/66kv 100MVA TR-1.

Tripping of elements with Relay indication at 400KV Kosamba

Substation on 18-11-2018, at 07:35Hrs Hrs. (BUS A & B):


Sr. No.

Name of Bay Kosamba end Opposite end

1 220 KV Kim line no.1 96 optd.

2 220 KV Bus Coupler 96 optd.

3 220 KV Zagadiya line No.1 Busbar prot. Zone A & B operated, (PU Internal LBB).

-

4 400/220 KV 315 MVA ICT- No.1

HV: inter trip LV: Busbar prot. operated

5 220 KV Kim line No.2 Busbar prot. operated -

6 220/66 KV 100 MVA TR No.2

HV Side: Busbar prot. Zone A operated LV Side : Inter trip

7 400/220kV 315 MVA ICT- No.2

HV Inter trip: LV :Busbarprot. Zone A operated

8 220/66kV 100 MVA TR No.1 HV :96 Optd LV : Inter trip

11 400/220kV 315 MVA ICT- No.3

HV Side :Inter trip LV Side : 96 optd. 86A/B optd,

12 400/220kV 315 MVA ICT- No.4

HV Side :Inter trip LV Side : 96 optd. 86A/B optd,

13 220kv Kosamba-Mota line Bus bar prot. operated ,96 Optd

14 220kv Kosamba-Zag line No.2

Bus bar prot. operated ,96 Optd

15 220kv Kosamba-Suva line Bus bar prot. operated ,96 Optd

16 220kv Kosamba-Vav line Bus bar prot. operated ,96 Optd

17 220kv Kosamba-Gavasad line

Bus bar prot. operated ,96 Optd

18 220kv Kosamba-GSEG line Bus bar prot. operated ,96 Optd

19 220kv Kosamba-Ichhapore line

Main-1: Zone-1, Bph to E, Ib:06:37kA,and second time Iy: 11.41kA, Ib: 11.00kA, Dist:13km. 86B Optd- Line taken on TBC at 11:36 Main-2: Zone-1, Bph to E, Ib:06:68kA and second time Iy: 10.71kA, Ib: 11.26kA, Dist:16.6km.86A Optd, 96 Optd Line taken on TBC at 11:35

Zone-1, Bph to E, 06:37kA A/R optd and tripped again Ir: 103A, Iy: 63.41A, Ib: 3.29kA, Dist:48.69km.

Last maintenance carried out on 220kv Ichhapore breaker: - Dtd 23.03.2018

I.R. value in GΩ

TERMINAL R ph Y ph B ph

Top to Bottom 78.2 GΩ 55.1 GΩ 69.9 GΩ

Bottom to Earth 81.3 GΩ 77.2 GΩ 51.8 GΩ

Top to Earth 126.2 GΩ 154.6 GΩ 111.9 GΩ


Dew Point Measurement of SF6 Gas Breaker ID Sampling

Point Dew Point °© atm.

Temp. °C RH%

220kv Ichhapore Line Sr.No.6756

R-Phase -48.5 31.5 1.0 Y-Phase -48.3 31.4 1.0 B-Phase - 46.6 32.0 1.2

DCRM taken on 23.03.2018 Single line diagram of the substation is as follows: -

Fault-1 :- B-ph to Earth Fault current 6.6KA Fault 2:- Y-B Phase to Phase. Fault current 11.7KA. 2ND FAULT

OCCURRED AFTER 445ms


b) Action Taken: After Inspection of cause and isolation of 220kv Ichhapore Line, 220kv

Bus B charged by 220kv Kim-1 at 8:00 hrs. and Then Bus coupler charged and so Bus-A charged.

Subsequently all bays connected in 220kv Bus taken in service.

After replacement of faulty 52CX contactor 220kv Ichhapore line taken in service on Transfer Bus-Couple at 11:35Hrs.

400 KV Kosamba substation: 220KV Kosamba –Ichhapore Line Main-1 relay DR

From Trip log of distance relay, Main-1(21.1) detects B-ph to E Faults. According to the single-phase fault AR cycle has initiated.

The Event report is enclosed as Annexure 2A.3. c) Committee observed the following; On operation of DPS the 220 KV Kosamba-Ichhaporeline fault should

have been cleared by 220 KV Kosamba-Ichhapore line breaker but as B-phase pole of breaker did not open due to defective 52cx auxiliary contactor and loose tripping wiring on TB in C&R panel of Ichhapore line.

Main root cause of unnecessary tripping of Bus – A was invalid status of 89 B isolator in Bus bar unit (87 BB) of 100 MVA TR-1.

Correct operation of numerical bus bar protection scheme is dependent on correct status of each isolator in bus bar bay unit.

Proper monitoring of isolator status is required to avoid this kind of trippings.


2A.4. Substation: 220 kV Mansar Date & time: 18.11.2018 at 06:12 hrs. Event Category: GI-1

2A.4.1: Event Summary:

On 18.11.2018 at 06:12 hrs there was a grid incidence at 220 kV Mansars/s.

At 220kV Mansar all the lines and ICTs including 400/220kV ICTs tripped on flashover of insulators due to dense fog.

Trippings observed are as follows: o 220 kV Mansar-Halvad D/C o 220 kV Mansar-Charadva D/C o 400/220 kV 315 MVA Mansar ICTs 1&2 o 220/66 kV 100 MVA Mansar ICTs 1&2

2A.4.2: Discussion in 135th PCM: GETCO representative informed the following;

Bus position of 220 KV feeders / transformers at the time of occurrence was as under.

220 KV Bus coupler breaker was “ON”. 220 kV TBC was “OFF”.

220 KV BUS A

1) 315 MVA 400/220 kV ICT-1 LV Side 2) 220 KV Charadva line-1 3) 100 MVA 220/66 kV TR-1 HV side 4) 220 KV Halvad line-1

220 KV BUS B

1) 315 MVA 400/220 kV ICT-2 LV side 2) 220 KV Charadva line-2 3) 100MVA 220/66 kV TR-2 HV side 4) 220 KV Halvad Line-2

a) Sequence/cause of occurrence: On 18-11-2018, 06:12 Hrs 220 KV Bus-A and B tripped at 400 KV

Mansar substation.

220 KV Bus-A tripped due to flashover B Phase pilot string insulator of 400/220 KV ICT-1 LV Side of 220 KV flyover bus (B Phase jumper connecting flyover bus to LV B Phase CT through pilot string touched to Bus-A R phase, after isolating from pilot string). Thus, bus differential protection Zone A operated, leading to tripping of all bays connected with 220 KV Bus A.


From DR of ICT-1 it is seen, B Phase current persists and breaker failure detected by PU. Further, ICT-1 tripped from 400 KV side though backup relay in E/F fault.

220 KV bus coupler also tripped but as mentioned above B Phase jumper of ICT-1 LV touched to Bus-A R-Phase.From DR, it is seen current persists in R phase of bus coupler which cause breaker failure detection by PU of bus coupler (B/C DR). All these events led to 87BB trip, 50 BF zone-1 trip & 50 BF zone-2 trip. So, all bays connected to Bus-B were also tripped.

Tripping of elements with Relay indication at 400KV Mansar Substation on 18-11-2018, at 06:12 Hrs. (BUS A & B):

Sr. No.

Name of Bay Mansar end Opposite end

1 315 MVA 400/220kV ICT-1 LV side

HV: E/F Trip, 86B LV: Busbar prot. Zone A operated,LBB, 86A & 86B

2 100 MVA 220/66 kV, TR no.1

HV: Busbar prot. Zone A operated LV: Intertrip

-

3 220 kV Halvad line-1

Busbar prot. Zone A operated

Direct trip Received

4 220 KV Charadava (Bhimasar) line-1



5 220 KV Bus Coupler Busbar prot. Zone A & B operated, (PU Internal LBB).

-

6 315 MVA 400/220kV ICT-2 LV side

HV: Intertrip LV: Busbar prot. Zone B operated

7 100 MVA 220/66 kV, TR no.2

HV: Busbar prot. Zone B operated LV: Intertrip

-

8 220 kV Halvad line-2

Busbar prot. Zone B operated


9 220 kV Chardava (Bhimasar) line-2

Busbar prot. Zone B operated



Single line diagram of the substation is as follows:-

Bus-A tripped due to failure of B-Phase string insulator of flyover bus towards 220 KV side. The differential current in B-Phase of central unit of bus bar protection scheme was 17.7 KA.

Bus-B tripped due to breaker failure detection(50BF) by bus coupler PU

as current in R-Phase persists approx. 800 A even after 200 msec,

Alstom makes Micom P-741743 Numerical bus bar protection scheme operated correctly.

Failure Equipment detail and last maintenance carried out: Brief name plate details of the ICT-1 220 kV BUS-A Flyover B-Phase

pilot string:

Make: AC INDIA Type: 120 KN Batch: 09-2012

Last maintenance of the CT-1 Bus A flyover Bus B Phase pilot string was carried out on 10-04-2018 and the porcelain insulating parts were cleaned with cotton cloth.

400 KV Mansar substation: B Phase Fault: Fault current about 17.7 KA.


Bus coupler R-Phase Current 800 A, even after 200 msec.


b) Action Taken:

Replacement of flashover pilot string with SRI carried out. Cloth

cleaning of other pilot strings of flyover bus of ICT-1 LV side was done. Also Bus A & B PT’s pilot string cloth cleaning done. Hot point was attended of ICT-1 LV side in R Ph bushing.

Brief name plate detail of the new ICT-1 220 kV BUS-A Flyover B-Phase SRI string:

Make: DECOSIL Type: 120 KN

Bus-A was charged at 16:20 hrs on 18-11-18 through 220 kV Charadva line-1 whereas other elements connected to BUS-A were subsequently charged.

Bus-B was charged with 220 kV bus coupler at 16:21 hrs on 18-11-18. Whereas other elements connected to BUS-B were subsequently charged.

The Event report is enclosed as Annexure 2A.4. c) Committee observed the following;

The main reason for operation of 220 KV Bus-A under bus differential protection Zone A, was due to flashover B Phase pilot string insulator of 400/220 KV ICT-1 LV Side of 220 KV flyover bus which resulted in tripping of all bays connected with 220 KV Bus A.

400/220KV ICT did not trip from the HV side on inter trip and it was continuously feeding the fault as the fault was prior to the LV side CB.

As the failed B phase insulator fell over the R Phase of 220 KV Bus 1, around 750 Ampers R- Phase current was seen in bus coupler DR. After 200 ms, the LBB of bus coupler initiated by its PU by seeing the current in R phase and resulted in tripping of 220 KV bus 2 even through the CB was in open condition.

The fault was B phase fault and it got cleared after 520 ms. The delayed tripping was due to non-tripping of HV side of Mansar ICT 1 on inter trip. PCM suggested washing of yard equipment must be carried out at regular intervals with increased frequency.


2A.5. Substation: 220kV Sikka

Date & time: 26.10.2018 at 13:10 hrs.

Event Category: GI-1


On 26.10.2018 at 13:10 hrs there was a grid incidence at 220 kV Sikka S/s.

At 220kV Sikka S/s, Main bus 2 tripped due to LBB protection maloperation. 250 MW Sikka units 3&4 connected to that bus tripped.

Trippings observed are as follows: o 250 MW Sikka Unit 3 o 220 MW Sikka Unit 4 o 220 kV Sikka Main bus 2

2A.5.2: Discussion in 135th PCM:

GETCO representative informed the following;

On 26.10.2018, the bus position at 220 KV Sikka TPS Switchyard (One and Half Breaker Scheme) was as under:

Following Generator/Transformer/Lines are in service:

1. GT – 3 (185 MW) 2. GT – 4 (185 MW) 3. Station Transformer - 3, 4 4. 220 KV Moti Paneli Line – 1, 2 5. 220 KV Jamanagr Line 6. 220 KV Jetpur Line 7. 100 MVA ICT – 3 8. 150 MVA ICT -4


At 13.10 Hrs, GT # 3, GT # 4, ST # 3 and ST # 4 tripped on Bus bar protection operation for 220 KV Bus-2 due to operation of LBB protection of ST # 3.

On detail checking at ST # 3 Relay panel, it was found that Display and HMI of ST # 3 LBB Relay (MICOM P123) was hang and communication port also non-interactive.

After communication started, it was found that Logic Input - 1 was became high, which is spare.

a) Events:

Logic input – 1, actually a spare, internally defined for use in future. It

is connected for initiation of LBB Relay. It gives LBB initiation for ST-3 and current was higher than setting, LBB tripping command to bus bar initiated.

No any primary Bus fault or Master trip relay operation for ST # 3 was found.

Input 1 not in use and spare but internally defined for use in future if required


As Bus-B tripped Bus bar protection, Unit-3 and 4 were tripped on turbine re- heater protection. As per reheat protection logic, feedback of HV Main breaker is used only but Tie breaker is not included. Hence, Turbine reheat protection operated even Tie breaker was ON.

The tripping was due to malfunction of LBB relay. LBB relay (MiCom

P123) for ST # 3 was replaced.

The re-heater logic was revised. Feedback of both Main and Tie breakers were included in DCS.

The Event report is enclosed as Annexure 2A.5. b) Committee observed the following; LBB relay of Sikka station transformer 3 mal-operated which resulted

in tripping of all the elements connected with the 220 kV Bus 2 on LBB operation.

After the tripping of GTs, the Units tripped on Turbine Reheat protection operation.

In plant inspection it was found that the Display and HMI of 50Z LBB relay of Station transformer 3 was in hanged condition, internal logic input 1 of the relay was found high during the tripping and it was a spare and not used for any tripping logic and so the faulty relay was replaced by a healthy one.

The current during the tripping was also found higher than the LBB setting ( I> 5% of 400 A), this need to be checked as there was no fault in the system.

MS informed that before the installation of the relays all the relay inputs settings are to be disabled first and during the installation the relay inputs which are needed to be functional, those inputs only enabled.

MS informed SOP need to be followed during the installation, testing of the relays at site.


2A.6. Substation: 400/220 kV Mansar

Date & time: 12.12.2018 at 11:54 hrs.


2A.6.1: Event Summary: On 12.12.2018 at 11:54 hrs there was a grid incidence at 400/220 kV

Mansar s/s.

At 400/220 kV Mansar s/s, flashover on Y phase pantograph isolator of 400 kV, 63 MVAr bus reactor led to the tripping of 400kV Bus 1 and all elements connected on BB protection operation.

Trippings observed are as follows: o 400/220 kV, 315 MVA Mansar ICT 1 o 400 kV Mansar-Bhachau (PGCIL) o 400 kV Mansar bus Coupler

2A.6.2: Discussion in 135th PCM:

GETCO representative gave a brief on the disturbance as follows;

The bus position of the 400KV feeders / transformers at the time of occurrence was as under: 400KV Bus coupler breaker was “ON”. 400KV Bus Reactor breaker was “OFF”, 89A PG isolator closed. 400KV Transfer Bus coupler breaker was “OFF”. 400KV Mansar-chorania Line breaker was “OFF” due to PSD.

400KV BUS A 1) 400/220 kV, 315MVA ICT no.1 2) 400 kV Bhachau(Bhimasar PGCIL) line 3) 400 kV Bus Coupler

400KV BUS B 1) 400/220KV, 315MVA ICT no.2


tripped due flashover of Y-Ph 89A (BUS-A) PG Isolator PI of 400 KV 63 MVAr Bus Reactor.

So, bus differential protection Zone A operated leading to tripping of all bays connected with 400KV Bus A with 400KV Bus Coupler.

Tripping of elements with Relay indication at 400KV Mansar Substation on 12-12-2018, at 11:54 Hrs. (BUS-A):

S.No. Name of Bay Mansar end Opposite end

1 400/220KV, 315MVA ICT no.1

HV: Busbar prot. Zone A operated LV: Intertrip

2 400KV Bhachau(Bhimasar)PGCIL line

Busbar prot. Zone A operated, DT SEND



3 400 kV Bus Coupler


-

Brief name plate details of Y-Ph 89A PG Isolator of 400 KV 63 MVAr Bus Reactor:

Make: Siemens Type: PG SR No: B0086-2-9 (M) Mfg year.: 2011 DOC: 23/01/15

Last maintenance activities of the Y-Ph 89A PG Isolator of 400 KV 63

MVAr Bus Reactor were carried out on11/08/18 and Water washing was carried onY-Ph 89A PG Isolator of 400 KV 63 MVAr Bus Reactor.


The Event report is enclosed as Annexure 2A.6. b) Committee observed the following;

Due to the flashover on Y phase PG isolator PI of 400 kV, 63 MVAr bus reactor, Bus Bar protection operated and tripped all the elements connected to bus 1 along with bus coupler.

Fault was cleared in 40 msec. ALSTOM male Micom P741/743 Numerical Bus bar protection scheme

operated correctly. 400 KV Mansar SS is located in saline atmosphere. Due to deposition of dust etc on PI of Y – Ph 89 A PG Isolator of 400 KV

63 MVAr Bus reactor, fault took place on 400 KV Bus A. PCM suggested washing of yard equipment must be carried out at regular intervals with increased frequency.


2A.7. Substation: 220/132 kV Godhra

Date & time: 13.12.2018 at 19:02 hrs.

Event Category: GD-1


On 13.12.2018 at 19:02 hrs there was a grid incidence at 220/132 kV Godhra s/s.

At 220/132 kV Godhra s/s, 220 kV side Y-Phase CT of 220/132kV 50MVA ICT 3 failed due to flashover. Heavy flames due to flash over resulted in 220 kV Bus 1& 2 tripping.

Trippings observed are as follows: o 220 kV Godhra- Kadana o 220 kV Godhra- Wanakbori o 220 kV Godhra-Chandrapura D/C o 220 kV Godhra-Savdas Na Muvada o 220/132 kV Godhra ICTs 1,2,3&4 o 220/66 kV Godhra ICTs 1,2&3

2A.7.2 :Discussion in 135th PCM:

GETCO representative gave a brief on the disturbance as follows; Bus position of 220 KV feeders / transformers at the time of occurrence

was as follows:-

220 KV Bus coupler breaker was “ON”.

220 KV BUS A 1) 220/132KV 150MVA TRANS-2 2) 220/132KV 50MVA TRANS-3 3) 220/66KV 100MVA TRANS-1 4) 220KV CHANDRAPURA LINE-1 5) 220KV KADANA LINE 6) 220KV WANAKBORI LINE

220 KV BUS B

1. 220/132KV 100MVA TRANS-1 2. 220/132KV 100MVA TRANS-4 3. 220/66KV 100MVA TRANS-2 4. 220/66KV 100MVA TRANS-3 5. 220KV CHANDRAPURA LINE-2 6. 220KV SAVDAS NA MUVADA LINE

Sequence/cause of occurrence:

On 13.12.2018 at 19.02hrs HV Y-Phase C.T of 220/132kV,50MVA Trans-3 failed with heavy flames due to flash over.


220/132Kv TR-3 was tripped in differential relay and HV & LV both breakers tripped.

As HV CT position is at Bus side, even after HV breaker tripped, the CT was charged by 220Kv Bus-A and therefore fault current feeding by Bus-A continued and it converted in to a bus Fault and Bus bar protection operated in dead zone. Thus, Bus-A connected all elements tripped with Bus coupler.

After 980ms of Bus-A tripping, due to wind direction the arc of failed CT reach in the induction zone of Y and B phase of 220kv bus-B, Zone-B differential bus bar protection operated. And this leaded to 220kv Godhra zero power.

Tripping of elements with Relay indication at 220KV Godhra Substation on 13-12-2018, at 19:02 Hrs. (BUS A & B):

Sr. No.

Name of Bay Godhra end Opposite end

1 220/132KV 150MVA TR-2 BB DEAD ZONE/ZONE-A TRIP

L.V INTER TRIPPED

2 220/132KV 50MVA TR-3 87 DIFF TRIP/BB DEAD ZONE/ZONE-A TRIP/LBB RETRIP

L.V INTER TRIPPED

3 220/66KV 100MVA TR-1 BB DEAD ZONE/ZONE-A TRIP

L.V INTER TRIPPED

4 220KV CHANDRAPURA LINE-1

BB DEAD ZONE/ZONE-A TRIP

NO RELAY NO TIPPING

5 220KV KADANA LINE BB DEAD ZONE/ZONE-A TRIP

NO RELAY NO TRIPPING

6 220KV WANAKBORI LINE BB DEAD ZONE/ZONE-A TRIP

NO RELAY NO TRIPPING

7 220/132KV 100MVA TR-1 BUS ZONE-B TRIP L.V INTER TRIPPED



10 220/66KV 100MVA TR-3 BUS ZONE-B TRIP TRANSFORMER ON

SHOCK CHARGED

11 220KV CHANDRAPURA LINE-2

BUS ZONE-B TRIP NO RELAY NO TRIPPING

12 220KV SAV DAS NA MUVADA LINE

BUS ZONE-B TRIP. NO RELAY NO TRIPPING

13 220KV BUS COUPLER BB DEAD ZONE/ZONE-A TRIP

-



DR Analysis: On dated 13.12.2018 at 19.02.18.268 Hrs HV Y-Ph. C.T of

220/132kV,50MVA Trans-3 failed.

At 19.02.18.298 Hrs i.e. after 30ms differential relay operated and master trip relay 86 operated and transformer gets tripped from H.V and L.V gets Inter tripped. Fault current was about 14KA. (refer F/B)

From the DR it is seen that 220kV Bus bar PU of 220/132Kv Trans-3 gets LBB initiation due to 86 operated and Breaker open status at 19.02.18.331 as breaker gets tripped.

As C.T location is at bus side Fault current was continuing in Y-Phase even though breaker was open.

From the DR analysis of TR-3 bus bar PU it can be seen that at 19:02:18.274 PU detected CT saturation Y-phase and then after B-phase CT saturation also detected at 19:02:18.379.

As per algorithm of Alstom Make P741/743 Bus bar protection scheme, it blocks bus-differential protection of all zones in case of CT saturation detection of any phase. And because of that Bus Zone-A differential protection not operated instantaneously.

As per D.R of trans-3 bus bar PU, at the starting of fault, the fault current was not continuously higher than Dead Zone pick-up value (720Amp) & LBB pickup Value (480 Amp).

From 19.02.18.361 Hrs. onwards current value in Y-Phase was continuously higher than LBB & Dead zone pickup value.


Also, at 19.02.18.372 Hrs. due to heavy flame from Y-phase, C.T tracking path created on B-phase C.T between P2 terminal and C.T tank and hence fault current on B-Phase Also started which can be seen from bus bar PU D.R

As LBB initiation persist and breaker open status was there in BB PU of trans-3 after 111 ms (Dead zone time delay 100ms) i.e. on 19.02.18.472 Hrs. Dead zone trip was initiated from Bus bar PU and all BUS-A feeders gets tripping. Also, same time LBB Re-trip signal tried to trip its own breaker (LBB Retrip time 100ms). But breaker was already tripped by differential protection. Total time taken for clearance of BUS-A fault is 268ms (Dead zone detection after 198ms + 70ms for all feeder breaker tripping time) . Refer F/D

CT saturation of Y-phase & B-phase which was detected by PU earlier was vanished at 19.02.18.534 and so that Bus Zone -A tripping initiated by BB at 19.02.18.546 Hrs. but before that Dead zone already initiated BUS-A trip.

All Bus-A feeders along with Bus coupler gets tripped. From the failed Y-Phase C.T heavy flame still coming out and as Y-Ph.

C.T location was just near to BUS-B and also wind direction was towards BUS-B air between Y-Ph. and B-Ph. Gets charged and flash over takes between Y & B Phase of BUS-B at 19.02.19.519 hrs. and Bus fault on BUS-B occurred, which can be confirmed from Savdas Na Muvada & Chandrapura line-2 BB PU D.R.

Due to above phenomena BUS-B gets operated at 19.02.19.528 Hrs. i.e. after approx. 980ms of BUS-A trip.

All feeders on BUS-B gets tripped.

b) Failure Equipment detail and last maintenance carried out:

Brief name plate details of the 220kv Y-phase CT of 220/132kv 50MVA TR-3:

Make: Mehru Type: Dead tank Sr No: OC 2966/3/9/10 Mfg Year: 2010 Capacitance:525pF %Ten-Delta: 0.25

Details of Ten delta and capacitance Measured of 220kv Y-phase CT of 330/132KV 50MVA TR-3:

Sr No

Make Mfg Year

Date of testing

% corrected

Capacitance C1 In pF

Remark

1 Mehru 2010 17.11.11 0.23 514.58 Name Plate Capacitance: 525pF 2 12.03.14 0.18 514.58

3 26.03.15 0.16 514.76


4 01.12.16 0.43 515.01 % Tan Delta: 0.25

5 07.06.18 1.50 513.35

220/132kv TR-3 Differential relay DR : fault current approx 14KA

220/132KV TR-3 Busbar PU DR: dead zone operated after 198ms of fault occurred


220/132KV TR-3 Busbar PU DR :Total Bus-A Fault clear time : 268ms

220kv Chandrapura line-2 DR: Bus Zone-B fault occurred at 19.02.19.519.

Total Time for clearance of Bus-B fault : 55ms

The Event report is enclosed as Annexure 2A.7.


c) Committee observed the following; On 13.12.2018 at 19.02hrs HV Y-Phase C.T of 220/132kV,50MVA

Trans-3 failed with heavy flames due to flash over.

220/132Kv TR-3 was tripped in differential relay and HV & LV both breakers tripped.

As HV CT position is at Bus side, even after HV breaker tripped, the CT was charged by 220Kv Bus-A and therefore fault current feeding by Bus-A continued and it converted in to a bus Fault and Bus bar protection operated in dead zone. Thus, Bus-A connected all elements tripped with Bus coupler.

After 980ms of Bus-A tripping, due to wind direction the arc of failed CT reach in the induction zone of Y and B phase of 220kv bus-B, Zone-B differential bus bar protection operated. And this leaded to 220kv Godhra zero power.

Protection operation of the transformer, Bus A and Bus B connected elements were found in order.

The failed C.T was manufactured in 2010. From the testing reports of the failed C.T, it can be observed that the tan delta (%) was continuously on raising trends.

GETCO representative informed that all the instruments used of the testing of C.T and other switchyard equipment were calibrated in the NABL accredited labs.


2B. Madhya Pradesh system

2B.1. Substation: 400/220 kV Pithampur

Date & time: 09.11.2018 at 04:37 hrs.


2B.1.1: Event Summary:

On 09.11.2018 at 04:37 hrs there was a grid incidence at 400/220 kV Pithampurs/s.

400/220 kV Pithampur ICT 2, HV side Y phase CT blasted resulting in tripping of all the 400 kV lines connected to Pithampur s/s along with 400/220 kV ICT 2 and 400 kV BR.

Trippings observed are as follows: o 400/220 kV Pithampur ICT 2 o 400 kV Pithampur-Indore D/C o 400 kV Pithampur-Singhaji D/C o 400 kV Pithampur BR

2B.1.2 :Discussion in 135th PCM:

MPPTCL representative informed the following;

On dated 09.11.18 at 04:37 hrs, following arrangement was in service at 400 KV S/s Pithampur.

400 KV Main Bus I 400 KV Main Bus II

400/220 KV ICT I 400/220 KV ICT II

400 KV SSTPH FDR I 400 KV SSTPH FDR II

400 KV PGCIL FDR I 400 KV PGCIL FDR II

2 x 50 MVAR Bus Reactor

At 04:37 hrs, 400 KV “Y” phase CT (BHEL/2012) of 400 KV ICT II failed and caught fire.

Consequently 400 KV ICT II tripped on differential protection and 400 KV Bus Bar Protection also operated for 400 KV Main Bus II selectively.

Therefore, 400 KV elements connected to 400 KV Main Bus II tripped on Bus Bar Protection along with 400 KV Bus Tie successfully.

Subsequently, within 3 seconds, the flame and broken porcelain pieces of failed CT shattered in the adjacent 400 KV Reactor bay caused flashover in the 400 KV Reactor Bay that resulted in to tripping of 400 KV Bus Reactor on back up protection as well as tripping of 400 KV SSTPH I & 400 KV PGCIL I feeders from remote end on “R” phase to ground fault Zone II protection. Since, this fault current was not significant, 400 KV ICT I was remain charged.

220 KV system was intact and no-load loss occurred.


Grid Disturbance at 400 KV S/s Pithampur on dt. 09.11.18DR of

400 KV ICT II

Grid Disturbance at 400 KV S/s Pithampur on dt. 09.11.18 DR of 2 x 50 MVAr Bus Reactor


a) Remedial Measures taken :

At 05:16 hrs 400 KV system resumed by charging of 400 KV PGCIL I and subsequently other 400 KV Feeders normalized up to 06:28 hrs.

400 KV failed CT replaced and 400 KV ICT II normalized on dated 10.11.18 at 12:53 hrs.

The Event report is enclosed as Annexure 2B.1. b) Committee observed the following: Main reason for the tripping of the 400 KV ICT II and 400 KV Main Bus

II was due to failure (caught fire) of 400 KV “Y” phase CT (BHEL/2012).

Subsequently, within 3 seconds, the flame and broken porcelain pieces of failed CT shattered in the adjacent 400 KV Reactor bay caused flashover in the 400 KV Reactor Bay that resulted into tripping of 400 KV Bus Reactor on back up protection as well as tripping of 400 KV SSTPH I & 400 KV PGCIL I feeders from remote end on “R” phase to ground fault Zone II protection. Since, this fault current was not significant, 400 KV ICT I was remaining charged.

Protection operation of the transformer, Bus A and Bus B connected elements were found in order.


2B.2. Substation: 220/132kV Tikamgarh

Date & time: 20.11.2018 at 12:03hrs Event Category: GD-1


On 20.11.2018 at 12.03 hrs there was a grid incidence at 220/132kV Tikamgarh s/s.

At 220/132kV Tikamgarh s/s, 132 kV side Y phase PT blasted and resulted in tripping of all the elements connected to 132 kV Bus. 132 kV Tikamgarh, Digoda, Pirthivpur, Jatara and Bhudera substations affected due to the event.

Trippings observed are as follows: o 220/132 kV 160 MVA Tikamgarh ICT 1 o 220/132 kV 160 MVA Tikamgarh ICT 2 o 132 kV Tikamgarh I/C 1&2 o 132 kV Tikamgarh-Budera D/C o 132 kV Tikamgarh-Jatara o 132 kV Tikamgarh-Digoda o 132 kV Tikamgarh-Pirthivpur o 132 kV Tikamgarh-Bijawer220KV Indore(MP)-Indore SZ-I

2B.2.2:Discussion in 135th PCM:

MPPTCL representative informed the following; On dated 20.11.18 at 13:03 hrs, 132 KV “Y” phase PT (SCT/2005) failed

at 220 KV S/s Tikamgarh and caused 132 KV Bus Fault, consequently following trippings occurred at 220 KV S/s Tikamgarh;

1. 160 MVA Transformer I tripped on High Set O/c protection. 2. 160 MVA Transformer II tripped on High Set O/c protection. 3. 132 KV Tikamgarh – Bijawar feeder tripped from remote end on “Y” phase to ground fault, Zone II, 72.33 kms.

Following 132 KV feeders hand tripped as these are radial feeders from 220 KV S/s Tikamgarh and no source available at other end.

1. 132 KV Tikamgarh interconnector I & II 2. 132 KV Prithvipur 3. 132 KV Digoda 4. 132 KV Jatara 5. 132 KV Budera I & II

220 KV system was remain intact during this occurrence.


At 12:58 hrs. after isolating the fault and fire extinguishing, 132 KV supply resumed through 132 KV Bijawar feeder, thereafter all the elements charged one by one as following;

a) Restoration of transformers and feeders are as follows:-

Name of /Transformer Feeder A-B

Time Duration Hrs. Tripping Charging

160 MVA EMCO Xmer 12:02 12:45 00:43

160 MVA BBL Xmer 12:02 13:54 01:52

132 KV Tikamgarh-Bijawar line

12:02 12:58 00:56

132 KV IC -I 12:02 13:11 01:09 132 KV IC -II 12:03 13:40 01:37

132 KV Prithvipur Line 12:03 13:17 01:14

132 KV Digoda Line 12:03 13:30 01:27 132 KV Budhera 1st Line 12:03 13:35 01:32 132 KV Budhera 2nd Line 12:03 15:15 03:12 132 KV Jatara Line 12:03 13:31 01:28

All the 132 KV feeders were charged after disabling the DPR protection and reducing the backup relay settings temporarily till the restoration of 132 KV PT supply.

132 KV PT replaced at 18:08 hrs on same day and all the protection normalized by 18:30 hrs.

The Event report is enclosed as Annexure 2B.2.

b) Committee observed the following:

Main reason for the trippings which were occurred at 220 KV S/s Tikamgarh was due to failure of 132 KV “Y” phase PT (SCT/2005) failed at 220 KV S/s Tikamgarh that resulted in 132 KV Bus Fault.

Further the radial feeders from 220 KV S/s Tikamgarh were hand tripped due to no source available at other end.

220 KV system was remain intact during this occurrence.


2B.3. Substation: 220 kV Sukha

Date & time: 03.12.2018 at 08:05hrs Event Category: GI-1


On 03.12.2018 at 08.05 hrsthere was a grid incidence at 220 kV Sukha s/s.

At 220 kV Sukha s/s, B phase jumper of ICT-1 snapped and resulted in tripping of all the elements connected to 220 kV bus 2 on bus bar protection operation.

Trippings observed are as follows: o 220 kV Sukha-Narsingpur-ckt 2 o 220 kV Sukha-Jabalpur(PG) 2 o 220 kV Sukha-Panagar 1

2B.3.2: Discussion in 135th PCM:

MPPTCL representative informed the following; 220 KV S/s Sukha (Jabalpur) is a switching substation of 220 KV

network and the 220 KV incomers connect this substation from 400/220 KV ICTs installed at 400 KV S/s Sukha (PGCIL).

On dated 03.12.18 at 08:05 hrs, following arrangement was in service.

220 KV Main Bus I 220 KV Main Bus II

220 KV Incomer ICT II 220 KV Incomer ICT I

220 KV Jabalpur FDR I 220 KV Jabalpur FDR II

220 KV Panagar FDR II 220 KV Panagar FDR I

220 KV Narsinghpur I 220 KV Narsinghpur II

At 08.05 hrs. 220 KV Bus Tie tripped on E/f, it was charged at 8.35 hrs. but tripped again. On checking unbalance current found on 220 KV Jabalpur II that was then hand tripped at 09:11 hrs.


At the same time 220 KV Panagar I tripped on E/f from remote end,

and then 220 KV Narsinghpur II tripped on E/f from Sukha end.

On through inspection of switch yard it is found that in the 220 KV Incomer I bay, the “B” phase jumper of Main Bus II isolator to Main Bus was snapped and hanging unearthed.

Therefore, the unbalance caused by open jumper condition resulted in to the tripping of 220 KV Bus Tie and 220 KV feeders connected to 220 KV Main Bus II at 220 KV S/s Sukha.

The 220 KV Main Bus I section at 220 KV S/s Sukha remain healthy and in service during this period.

There were no load loss or generation loss occurred due to this event. 220 KV Main Bus II normalized at 14:43 hrs after rectification of fault

and then all 220 KV elements normalised one by one.


Committee observed the following: Committee observed that the main reason for the tripping of 220 KV Bus

Tie and 220 KV feeders connected to 220 KV Main Bus II at 220 KV S/s Sukhawas due to unbalanced current caused by 220 KV Incomer I bay “B” phase jumper of Main Bus II isolator to Main Bus was snapped and hanging unearthed.


2B.4. Substation: 220 kV Jabalpur

Date & time: 09.12.2018 at 11:17 hrs Event Category: GD-1


On 09.12.2018 at 11.17 hrs there was a grid incidence at 220 kV Jabalpur s/s.

At 220 kV Jabalpur s/s, 220 kV Bus 1&2 tripped along with all the connected elements due to B phase fault on Bus 1 caused by monkey.

Trippings observed are as follows: o 220 kV Jabalpur- Amarkantak D/C o 220 kV Jabalpur-Birsingpur D/C o 220 kV Jabalpur-Narsingpur o 220 kV Jabalpur-Sukha o 220/132 kV 160 MVA Jabalpur ICTs 1&2 o 220/132 kV 120 MVA Jabalpur ICTs 1&2

2B.4.2: Discussion in 135th PCM:

MPPTCL representative informed the following; At 08.05 hrs. 220 KV Bus Tie tripped on E/f, it was charged at 8.35

hrs. but tripped again. On checking unbalance current found on 220 KV Jabalpur II that was then hand tripped at 09:11 hrs.

At 220 KV S/s Jabalpur, 220 KV double main and transfer bus arrangement is in service. There is GE make B-90 Bus Bar Protection scheme is in service.

In the month of November’18, the power supply module of LBB /Logic unit of this Bus Bar Protection scheme gone defective and due to some problem in Main Bus II elements, this Bus Bar scheme was kept out of service for 220 KV Main Bus II but for 220 KV Main Bus I it was remain in service.

On dated 09.12.18 at 11:17 hrs a monkey fault occurred on 220 KV Main Bus I at 220 KV S/s Jabalpur and caused operation of 220 KV Bus Bar Protection for 220 KV Main Bus I, but simultaneously 220 KV elements connected to 220 KV Main Bus II also got tripped on Bus Bar protection.

That caused total interruption to 220 KV S/s Jabalpur area for about 34 minutes.


At 11:28 hrs. 220 KV supply resumed through charging of 220 KV

Sukha I feeder and then all other elements normalized one be one, by 11:51 hrs. total supply normalized at 220 KV S/s Jabalpur.

On analyzing the event, it is found that due to logic issue and defective power supply module of LBB/Logic unit, the bus bar protection has seen as both buses / Z1 & Z2 are connected and treated it as a single bus, that has caused this tripping.

The defective DC power supply module of LBB/Logic unit is replaced by a spare one and 220 KV Bus Bar protection scheme is taken back in to the service. It is under observation.


Committee observed the following: On dated 09.12.18 at 11:17 hrs due to monkey a fault occurred on 220

KV Main Bus I at 220 KV S/s Jabalpur and caused operation of 220 KV Bus Bar Protection for 220 KV Main Bus I. The protection operated was found in order.

Simultaneously the tripping of 220 KV elements connected to 220 KV Main Bus II on Bus Bar protection was due to logic issue and defective power supply module of LBB/Logic unit. Bus bar protection has seen as both buses / Z1 & Z2 are connected and treated it as a single bus, that has caused this tripping.

MPPTCL representative informed that similar type defective power supply module of LBB/Logic unit, GE make were observed in the previous stages also.

MS requested that the reason for the failure of power supply module of LBB/Logic unit of GE make need to be analyzed and the report should be submitted to the committee at the earliest.


2B.5. Substation: 220 kV Ujjain

Date & time: 10.12.2018 at 23:39hrs Event Category: GI-1


On 10.12.2018 at 23.39 hrsthere was a grid incidence at 220 kV Ujjain s/s.

At 220 kV Ujjain s/s, while synchronising 220 kV Ujjain- Indore (PG) 2, LBB of the line maloperated and all the elements connected to 220 kV Bus 2 tripped.

Trippings observed are as follows: o 220 kV Ujjain-Indore (PG) 2 o 220 kV Ujjain-Badod D/C o 220 kV Ujjain-Nagda 2 o 220/132 kV 160 MVA Ujjain Ict 2

2B.5.2 :Discussion in 135th PCM: MPPTCL representative informed the following; 220 KV S/s Ujjain has single 220 KV main bus and one auxiliary bus

arrangement, but 220 Main Bus is sectionalized in two section which are connected through 220 KV Bus Tie.

On dated 10.12.18, the work of LILO of 2 x 220 KV Ujjain Hathuniya (765 KV S/sPGCIL Indore) feeders was going on.

At 23:38 hrs, 220 KV Ujjain – Hathuniya (PGCIL) ckt. I charged at Ujjain end, it stood Ok.

At 23:39 hrs, 220 KV Ujjain – Hathuniya (PGCIL) ckt.II charged at Ujjain end, but LBB scheme of this feeder operated at Ujjain end that resulted in to tripping of 220 KV Bus Tie and all the elements connected to 220 KV Main Bus Section II.

220 KV Main Bus Section I at 220 KV S/s Ujjain was remain intact and in service during this event, therefore there were no interruption occurred to any area due to this trippings.


At 00:00 hrs (11.12.18), 220 KV supply resumed to 220 KV Main Bus section II through charging of 220 KV Bus Tie at 220 KV S/s Ujjain. Thereafter, all the 220 KV elements on this bus section normalized one by one except 220 KV Hathuniya (PGCIL) feeders.

On detail investigation of event, it is found that the LBB scheme mal operated due to mistaken assignment of voltage sensitive contacts meant for trip circuit supervision to LBB scheme in GE make D-60 DPR. This relay was commissioned on same day.

Relay programme has been corrected accordingly and tested for healthiness and then taken in to service.

The LILO of 220 KV Ujjain Hathuniya (PGCIL) Ckt. I & II has been taken in to service on dated 12.12.18 at 21:13 hrs.

The Event report is enclosed as Annexure 2B.5. Committee observed the following: Main reason for the tripping of all the elements connected to 220 kV

Bus 2, at 220 kV Ujjain s/s was due mal operation of LBB scheme.

While synchronising 220 kV Ujjain- Indore (PG) 2,LBB scheme mal operated due to mistaken assignment of voltage sensitive contacts meant for trip circuit supervision to LBB scheme in GE make D-60 DPR.

MS asked whether the functional test done for the mal operated relays were satisfactory and whether all the relay setting contacts were properly arranged.

MPPTCL representative informed that functional tests were done on the mal operated relay and the reports were found ok.

MS opined that reasons for the mal operation of the relays need to be analysed.


2C. Maharashtra system

2C.1. Substation: 220 kV Bhugaon (MH)

Date & time: 04.11.2018 at 12:21 hrs. Event Category: GD-1

2C.1.1: Event Summary:

At Bhugaon(MH), Y-ph wave trap of 220KV Wardha-Bhugaonckt 1 decapped but the Y phase pole CB of 220KV Wardha-Bhugaonckt 1 failed to open and resulted in tripping of 220KV Bus 1 on LBB operation. Due to the Non-availability of PT supply Bus 2 also tripped during the event.

Trippings observed are as follows: o 220 kV Bhugaon-Wardha (PG) o 220 kV Bhugaon-Purti o 220 kV Bhugaon-IIPL o 220 kV Bhugaon-Warora D/C o 220 kV Bhugaon-Wardha (MH) o 220 kV Bhugaon-Hinganghat o 220 kV Bhugaon-LLOYDS o 220 kV Bhugaon-UGML o 220/132 kV 100 MVA Bhugaon ICTs 1&2 o 1220/33 kV 50 MVA ICTs1&2

2C.1.2 :Discussion in 135th PCM: MSETCL representative informed the following;

On dtd04.11.2018 at 12:20 hrs ,220KV PGCIL line tripped, due to decapping of Y-phwavetrap at 220KV Bhugaon S/s .

220KV PGCIL Ckt Y-ph Breaker pole failed to open within 200msec,resulted in LBB operation of SEL 487B Numerical Busbar scheme .

220KV Bays connected to Bus Section I along with Hybrid Bus Sectionaliser tripped.

220KV Bays emanating from Bus section- 2, also tripped on Zone 4 due to non-availability of PT supply.


On dtd 04.11.18, PGCIL line CB failed to open within 200msec , for Y-PH WT decapping fault, resulted in operation of LBB of 220KV Numerical Bus bar scheme (SEL 487B) .

Tripping all bays connected to Bus section I along with Hybrid Bus sectionaliser.

Presently 220KV Bus section I PT (CGL make) supply is extended to Bus section II feeders through Bus sectionaliser.

After tripping of Bus section I on LBB, PT supply was not available to feeders connected to Bus section II resulted in tripping of feeder (220KV Wardha , Warora I & II & 220KV Hinganghat) connected to Bus section II in Zone 4.

a) Remedial action taken by MSETCL :- CB did not tripped due to mechanical jam:- Mechanical problem of

220KV PGCIL Circuit Breaker was attended & at the same trip coil of B-pH TC1 found weak same was replaced.

CRM & CB Timing results found in order.


Date CRM

CB TIMING

06.11.18 RY B 40.7

39.3 38.8

R Y B Close 90msec

88msec 86msec TC1 20msec

22msec 22msec TC2 29msec

27msec 27msec

Initially there was only single Bus system and single PT supply was

extended to all feeders.

After occurrence, second PT source was made available & same was extended to Bus section II ondtd05.12.2018, to avoid such recurrence in near future.

The Event report is enclosed as Annexure 2C.1. b) Committee observed the following: Due to decapping of Y-phwavetrap at 220KV Bhugaon S/s ,220KV

PGCIL line tripping command was issued, but 220KV PGCIL Ckt Y-ph Breaker pole failed to open within 200msec, resulted in LBB operation of SEL 487B Numerical Busbar scheme .

220KV Bays connected to Bus Section I along with Hybrid Bus Sectionaliser tripped.

220KV Bays emanating from Bus section- 2, also tripped on Zone 4 due to non-availability of PT supply.

MSETCL representative informed that initially there was only single Bus system and single PT supply was extended to all feeders. After occurrence, second PT source was made available & same was extended to Bus section II on dtd 05.12.2018, to avoid such recurrence in near future.

MS informed the cause of 220KV PGCIL Ckt Y-ph Breaker pole failed to open within 200msec need to be analysed and also informed that proper maintenance of CB may reduce these type of incidents.


2C.2. Substation: 400/220 kV Aurangabad(MH)

Date & time: 06.11.2018 at 13:28 hrs. Event Category: GI-2


At Aurangabad(MH), all the elements connected to the 400 kV Bus 1 tripped due to 400 kV Bus 1 bus bar protection operation.

Trippings observed are as follows: o 400/220 kV Aurangabad (MH) ICT 1&2 o 400 kV Aurangabad (MH)-Aurangabad (PG) ckt 2 o 400 kV Aurangabad (MH)-Babhleshwar o 400 kV Aurangabad (MH)-Pune (GIS) 2

2C.2.2: Discussion in 135th PCM: MSETCL representative informed the following;

On date 06/11/18 at 13:28 hrs at 400kV Waluj S/S it was observed that industrial waste aluminum foil paper wrapped on 400kV Bus-I connected to R-Ph 29-A isolator of ICT-I.

This resulted into heavy flashover and operation of Bus-Bar Protection Zone-I R-Ph resulting into tripping of all bays connected to respective bus along with bus-coupler.

Loading condition before and after operation of Bus-bar protection at 400kV Waluj S/S


SrNo Bay Name Bus Load before occurrence

Load after occurrence

1. 400kV ACPG-I II 426 MW (Imp) 416 MW (Imp)

2. 400kV ACPG-II I 430 MW (Imp) 0 MW

3. 400kV Pune-I II 230 MW(Exp) 259 MW (Exp)

4. 400kV Pune-II I 228 MW (Exp) 0 MW

5. 400kV Babhaleshwar I 272 MW (Exp) 0 MW

6. 400kV Bhuswal II 83 MW (Imp) 67 MW (Imp)

7. 400/220kV 315 MVA ICT-I I 132 MW (Exp) 0 MW

8. 400/220kV 315 MVA ICT-II I 132 MW (Exp) 0 MW

9. 400/220kV 500 MVA ICT-III II 208 MW (Exp) 311 MW (Exp)

10. 400kV Deepnagar I 118 MW (Imp) 0 MW

11. 400kV ThapatiTanda II 140 MW (Imp) 94 MW (Imp)

Bus operation was in order and the elements connected to Bus-II were in service. No load affected as the load gets managed on 220kV sources and ICT-III.

a) DR and SOE

Existing Bus bar scheme at 400kV Waluj is ABB Make RADSS. Being static bus bar protection scheme DR and SEL recording facility

is not available.

This scheme is being replaced by new numeric ZIV make bus-bar protection scheme and work is in progress.

It is expected to get the new bus bar protection scheme commissioned up to March-19.

The Event report is enclosed as Annexure 2C.2.

b) Committee observed the following: PGCIL WRTS-1 representative informed that, DT was not received at

Pune end and the line remained in charged condition from Pune end.

MS enquired about what is the reason for non-receival of DT at Pune end and informed that MSETCL need to check why DT not sent to the remote end in coordination with PGCIL.

PGCIL WRTS-1 representative informed that DT was sent from Deepnagar end but the receiver count of channel D was not increasing at Deepnagar end.

MSETCL representative informed that they attended the both issues and increased the receiver count of channel D at Deepnagar end.


2C.3. Substation: Ektuni

Date & time: 08.11.2018 at 07.11 hrs. Event Category: GI-2


Due to Mal-operation of 765 kV Bus bar protection operation, 765 kV Bus 1 at Ektuni tripped.

Trippings observed are as follows: o Tripping of 765 kV Ektuni Bus 1

2C.3.2 :Discussion in 135th PCM:

MSETCL representative briefly described the disturbance as per their report :-

On date 08/11/18 at 07:12 hrs at 765kV Ektuni (MSETCL Aurangabad) S/S there was operation of bus bar protection Main-I, Zone-I

This resulted into tripping of all bays connected to 765kV Bus-I

Being 1-1/2 breaker scheme no supply get affected. On visit to the control room it is observed that there is communication

error of PU.

To check which PU has gone faulty visited individual BCR.

On observation in BCR for 705 bay it was observed that PU-A of this bay was not communicating to CU.

SLD Showing Busbar protection scheme:


a) DR analysis:- There is Two bus bar scheme CU provided for protection of Bus viz.

Main-I and Main-II.

Each bay connected to Bus has two PU units PU-A and PU-B. All PU-A Reports to Bus-bar protection Main-I and PU-B to Main-II

Each Bus-bar CU has two zones to trip Bus-I or Bus-II SLD Showing Operation of Bus bar protection:

On date 08/11/18 PU-A of 705 Bay became faulty and lost the

communication with CU.

Before to loss of communication; it was expected to block the Main-I Zone-I.But instead of getting it block it has issued tripping command whichresulted into tripping of breaker 702, 705, 709, 711

Being 1-1/2 breaker scheme supply affected was nil.

The Event report is enclosed as Annexure 2C.3. b) Committee observed the following; Main reason for tripping of 765 kV Bus 1 at765/400 KV Ektuni SS was

due to mal-operation of 765 kV Ektuni Main 1 BB relay.

705 bay Peripheral unit (PU) was having communication issues with the BB central unit.

MS requested to analyze the reason behind PU-A of 705 Bay became faulty and lost the communication with CU and the ascertain the healthiness of the Main 1 BB relay.


2C.4. Substation: Bhusawal



400 kV Bhusawal 50 MVAR BR caught fire and the fire got spread to the nearby control cables followed by the hand tripping of 400 kV Koradi, Akola, Aurangabad, Bhablseshwarckts at Bhusawal substation.

Trippings observed are as follows: o Tripping of 400 kV 50 MVAR Bhusawal BR

2C.4.2:Discussion in 135thPCM:

MSETCL representative briefly described the disturbance as per their report

On Dt. 10/11/2018, 50MVAr, 400kV Bus Reactor burst at 13:38 hrs after charging at 11:07 Hrs.

Diff relay, OC & EF relay (OC & EF high set for R and Y ph), REF relay issued tripping instantaneously.

Fault was initiated in Y ph and ground as per DR from Diff and OC & EF protection after 45ms fault was also initiated in R ph.

PRV Trip issued after 45ms as per Diff, relay DR.

Due to reactor burning oil spillage, nearby cable trench caught fire. Due to this, control cables of 400kV Akola, 400kV Koradi, 400kV Babhaleshwar and 400kV Akola line damaged and said lines hand tripped from khadka end.

a) Analysis

The Bus reactor was in working through TBC bay and it was decided to shift the BUS Reactor on newly Constructed bay. To carry out the work, outage was availed on date 01.10.2018 @14:45hrs, to shift the reactor on newly constructed bay.

After shifting of reactor on date 10.11.2018, all the necessary pre-commissioning testing of reactor was carried out and results found in order.

The Bus reactor was charged on date 10.11.2018 @11:07hrs. And stood ok. Staff recorded/Measured Temperature and also carried out thermo-vision scanning.


SLD Before Occurrence.

SLD After Occurrence

b) Restoration

Sr. No.

Name of Feeder/bays

Date & Time Duration (hrs)

Remark From To

1 50 MVAr 400 KV Bus Reactor

10.11.2018 ,13:38 Hrs

Not restored

Reactor Bursted

2 400KV Khadka-koradiCkt

10.11.2018,13:44 Hrs

14.11.18,16:12 Hrs

98:28 Hrs

3 400KV Khadka-Akola ckt

10.11.2018,13:45 Hrs

13.11.18,00:27 Hrs

58:42 Hrs


4 400 Kv Khadka-Aurangabad ckt

10.11.2018,13:49 Hrs

15.11.18, 23:05 Hrs

129:16 Hrs

400 KV Khadka-Aurangabad Ckt was ready for charging but charged on date 16.11.2018 7:11 Hrs. as per LD

5 400KV Khadka-Babhaleshwarckt

10.11.2018,13:51 Hrs

13.11.18,22:48

80:57

c) Remedial Measures

Proposed for internal inspection to investigate cause of failure/Burst.

NIFPS or firefighting system to be incorporated. Main cable trench near ICT/TFR/Reactor to be kept sufficient

distance to restrict spread of fire/ to provide desirable protective fire covering.

DR Differential Relay:


DR Differential Relay:

The Event report is enclosed as Annexure 2C.4. d) Committee observed the following; On 10.11.2018 around13:38 Hrs, R phase bushing of BR got burst and

caught fire, the fire spread to the nearby cable trench and the control cables in the trench also caught fire. It resulted in operation of Buchholz and differential protection operation of the reactor.

400 kV Koradi, Akola, Bableshwar and Aurangabad tripped during the event and handtripped at the respective remote ends.

The tripping of the 400 kV lines may be due to the DC fluctuations resulted due to the fire in control cable.

MSETCL representative informed that corporate office committee constituted to look into the failure of Bus reactor.

MS informed that, to avoid such occurrences, the list of equipments which crossed their useful life span to be listed and testing activities may be carried out to ensure their healthiness as the blasted BR was of 40 years old.

MS also informed to submit the copy of corporate office committee constituted to look into the failure of Bus reactor to WRPC at the earliest.


2C.5. Substation: 400/220 kV Padghe



At 400/220 kV Padghe s/s, B phase CT of 400 kV Padghe HVDC 1 blasted and resulted in tripping of 400 kV Padghe-Padghe HVDC 1, 400 kV Padghe-Kalwa D/C and 400 kV Padghe-Tarapur 2 due to the fire and smoke.

Trippings observed are as follows: o 400 kV Padghe HVDC 1 o 400 kV Padghe-Kalwa D/C o 400 kV Padghe-Tarapur 2

2C.5.2: Discussion in 135thPCM:

MESTCL representative informed the following;

At 02:45Hrs on 11.12.2018 400kV HVDC-1 Bph LUSTRE Make 7 Core CT burst & caught fire. This fault was seen by AC filter Bus Differential Protection at +/-500kV HVDC Padghe Terminal Station.

Hence CB of 400kV HVDC-1 in 400kV RS switchyard tripped along with other CBs connected to AC filter bus at +/-500kV HVDC Padghe Terminal Station.

As the running system grid voltage was high, 400kV Padghe-Kalwa-1 & 400kVPadghe-Tarapur-2 lines tripped on Overvoltage Stage-1 Protection at the same time of occurrence.

During the occurrence, fire flames & smoke of Burst CT of 400kV HVDC-1 reached out to the adjacent Rph of 400kV Padghe-Kalwa-2 line which lead to the Phase to Earth fault on the line.

As the fault was seen by Distance relays at Padghe end (Rph-E, Zone-1, 0.3kms) & at Kalwa end (Rph-E, Zone-2, 51.5kms), 400kV Padghe-Kalwa-2 line tripped on distance Protection Operated at Both ends.

As the system voltage was high, 400kV Padghe-Kalwa-1 & 400kV Padghe -Tarapur-2 lines could not be charged immediately. Hence those lines were charged after normalization of system voltage with SLDC, Kalwa Permissions (i.e. 400kV Padghe-Kalwa-1 & 400kV Padghe-Tarapur-2lines charged @07:15Hrs & @08:53Hrs Dated:11.12.2018 respectively.

400kV Padghe-Kalwa-2 line Rph CT porcelain surface was damaged due to bursting of CT. Thus Rph CT of 400kV Kalwa-2 was tested for its Capacitance & Tan Delta Values. As results of Rph CT were found normal, 400kV Padghe-Kalwa-2 line also taken into service @08:36Hrs Dated:11.12.2018.

The Burst Bph CT of 400kV HVDC-1 was dismantled & due the non-availably of 7 Core 400kV CT (except the available 7 Core CT of


M/s. LUSTRE Make), it was decided to install ABB Make 5 Core 2000/1000/500-1A CT which was installed on 400kV A-Bus SectionalizerYph.

Same CT was removed & diagnostic tests were carried out. After confirming its test results, CT was commissioned on Bph of 400kV HVDC-1 line.

During this occurrence, Yph CT of 400kV HVDC-1 was also tested for Capacitance & Tan Delta as it was adjacent to Burst CT & Results were found normal.

Also, 2 stacks of Rotary Insulator of Yph C-Bus Isolator of 400kV HDVC-1 were damaged & same were replaced by 400kV Maintenance Unit, Padghe.

As the R, Y, B phase LA were very near to the Burst CT, little bit of their porcelain bodies was damaged. Thus, their IR Values were taken & found ok.

All the outer cleaning of equipment porcelain bodies near to burst CT were carried out by 400kV Maintenance Unit, Padghe.

After completing all above activities, 400kV HVDC-1 line was charged @ 20:28Hrs Dated:11.12.2018.


The Event report is enclosed as Annexure 2C.5. Committee observed the following; The main reason for tripping of CBs connected to AC filter bus at +/-

500kV HVDC Padghe Terminal Station was due to failure of B-phase CT of 400 KV Padghe HVDC 1.

Fire flames & smoke of Burst CT of 400kV HVDC-1 reached out to the adjacent Rph of 400kV Padghe-Kalwa-2 line which lead to the Phase to Earth fault on the line.

Tripping of CBs connected to AC filter bus at +/-500kV HVDC Padghe Terminal Station 400kV Padghe-Kalwa-2 line were in order.


2C.6. Substation: 400/220 kV Khargar



At 400/220 kV Khargar s/s, 220 kV Bus 1& 2 along with bus coupler tripped on LBB operation of 220 kV Bus coupler.

Trippings observed are as follows: o 220 kV Khargar- Uran D/C o 220 kV Khargar- Borivalli D/C o 220 kV Khargar- Panvel o 220 kV Khargar- Nerul o 220 kV Khargar- Topwarth o 220 kV Khargar- Sonkhar o 400/220 kV 315 MVA ICT 1,2&3 o 220/33 kV 50 MVA ICT 1,2&3

2C.6.2: Discussion in 135th PCM:

MSETCL representative informed the following;

On 11.12.2018 at 13:45 hrs. 220 KV Bus Coupler LBB opearated, with

tripping of 220KV feeders connected to 220kV Bus-A & B at 400 KV

Kharghar Sub-Station.

It was observed that during commissioning of new 220kV NR make

numerical Bus bar protection panel, LBB initiation contact got

extended from NR make new Bus bar panel to 220kV Bus coupler LBB

Relay.

Normally current in 220kV Bus coupler was below LBB relay setting

(LBB relay setting is 0.8A & 200ms).

But dt- 11.12.2018 at 13:45 hrs 220kV Bus coupler current exceeded

above 0.8A due to fault on 220kV Nerul- Trombay line.

Hence 220kV Bus coupler bay’s LBB protection operated in 200ms. Due

to this LBB operation there is no chance for operation of main

protection of 220kV Kharghar-Nerul line in Zone2/Zone 3protection

(Zone 2 & Zone 3time delay is 400ms& 700ms respectively).


The Event report is enclosed as Annexure 2C.6. Committee observed the following: There was no actual fault present in the system, however the tripping’s

were due to LBB initiation contact got extended from NR make new Bus

bar panel to 220kV Bus coupler LBB Relay which resulted into 220 KV

Bus Coupler LBB operation.

MS opined that care should be taken while carrying out the wiring in

live condition.


2C.7. Substation: 400/220 kV Padghe



At 400/220 kV Padghe S/S,Y phase CT of 400kV Tarapur 2 blasted, resulting into tripping of all 400 kV Lines / ICTs on 400 kV Bus 1 along with Bus coupler.

Trippings observed are as follows: o 400 kV 315 MVA Padghe ICT 2 o 400 kV Padghe-Babhaleshwar 2 o 400 kV Padghe-Kalwa 2 o 400 kV Padghe HVDC 1 o 400 kV Padghe-Nagothane 1 o 400 kV Padghe-Tarapur 2


MSETCL representative informed the following;

At 04:48 hrs on 28/12/2018 Y phase CT of 400kV Padghe-Tarapur ckt-2 burst, resulting into tripping of all 400 kV Lines / ICTs on Bus-A & 400 kV BusCoupler, due to operation of 400kV A-bus busbar protection. This resulted into major damage to 500MVA 400/220kV ICT-5 B phase radiator and damages the porcelain of B phase bushing. Also, Tarapur-2 R ph CT porcelain was damaged.

AT 4:48Hrs on 28.12.2018 400kV Tarpur-2 Yph ABB Make CT burst & caught fire. This fault was seen by Bus Differential Protection (Busbar Relay) at 400kV Padghe Substation.

Hence CB of 400kV Tarpur-2 tripped along with other CBs connected to “A” Bus at Padghe Substation

During the occurrence, Other R-phase CT Porcelain get damage and small amount of oil leakage start.

Due to CB problem at 400kV Nagothane end, the feeder taken into service @ 15:45Hrs after attending the problem of CB at Nagothane end.

400kV Padghe-Tarapur-2 line R phase CT porcelain surface was damaged and oil leakage due to bursting of Y phase CT.

Thus defective R phase CT and Burst Y phase CT replaced with New Areva make CT’s after testing work done by M/s. PGCIL.

400kV Padghe-Tarpur-2 line also taken into service @09:50Hrs dated:30.12.2018.


The Event report is enclosed as Annexure 2C.7. Committee observed the following:

The main reason for the tripping of all 400 kV Lines / ICTs on Bus-A & 400 kV Bus Coupler was due to failure of Y phase CT of 400kV Padghe-Tarapur ckt-2 which resulted into operation of 400kV A- busbar protection.

Similar type of failure of 400kV HVDC-1 Bph LUSTRE Make 7 Core CT was observed on 11.12.2018 at +/-500kV HVDC Padghe Terminal Station.

MS enquired about the tests which were conducted on the failed CT and also opined to analyze the reasons for the failure of the CT’s in the same substation.

MSETCL representative informed that failed CT was dead tank CT and also informed that MSETCL now going for live tank type of CT’s.


2C.8 Substation: 220kV Pedhambe


(134th PCM Agenda item no 2C.12. MAHAGENCO representative was not present in the 134th PCM meeting and therefore the following disturbance could not be explained to the sub-committee. The same is taken up in the 135th PCM for discussion.)


At 220kV Pedhambe, all the elements connected to the 220 kV Bus section 2 tripped on Pole discrepancy of Unit 11 CB.

Trippings observed are as follows: o 220 kV Pedhambe(Koyna stage III)- Adlab o 220 kV Pedhambe(Koyna stage III)-Pophali o (Koyna stage 1&2)ckt-2 o 220 kV Pedhambe(Koyna stage III)-Oni o 220 kV Pedhambe(Koyna stage III)-Nerale o 80 MW Koyna Unit 11&12


MAHAGENCO representative informed the following:

On 26/03/2018, while withdrawing Unit No. 11 from grid, Unit tripped on Pole Discrepancy. It is observed that, Y phase breaker pole tripping coil found burnt, same is replaced. All 3 phase breaker poles operating mechanism checking done, found OK. Breaker pole timing checked, found within limit.

On 24/09/2018, Unit No.11 is on bar and tripped on Distance protection and Pole Discrepancy operated. Also 220 KV bus section- II tripped on LBB protection. As a result, Unit No. 12 on same Bus and all lines also tripped.

On 26/09/2018, All 3 phase breaker poles operating mechanism checking done, found OK. Breaker pole timing checked, found within limit.

After this occurrence Higher authorities suggested to take cold trial of Unit No. 11 Gen. Bkr. Once in a week. Till dt. 17/11/18, Bkr. Operation found normal.

On17/11/2018, while taking cold trial of bkr. Pole discrepancy appeared. Hence, detail checking of pole mechanism carried out. Y phase breaker pole tripping coil found burnt. Same is replaced. Y-phase bkr. Pole trial taken, found normal. After this, all 3 phase breaker poles operating mechanism checking done. Breaker pole timing checked. R &B phase pole working normal, but B phase pole stuck up during opening. Detail checking of breaker done, found that moisture (water)


observed in Air expansion chamber. Hence, it is decided to call external agency to carry out detail checking of breaker.

On 10/12/2018, M/s Electro met Projects, Nashik Service Engineer is arrived for attending 220 KV SF6,CGL make breaker trouble of unit No.11,The breaker operation checked & found control valve assembly jam. Control valve assembly dismantled & its overhauling carried out. Reassembled & refitted control valve assembly. Breaker operation trial taken found normal.

After completion of work, till date PDR is not operated. SINGLE LINE DIAGRAM OF SWITCHYARD

The Event report is enclosed as Annexure 2C.8. Committee observed the following:

On 24/09/2018, Unit No.11 is on bar and tripped on Distance protection and Pole Discrepancy operated. Also 220 KV bus section- II tripped on LBB protection. As a result, Unit No. 12 on same Bus and all lines also tripped. Tripping of 220 KV bus section- IIon LBB protection found in order.

PCM observed that accurate analysis is required to be undertaken by MAHAGENCO in order to prevent frequent trippings mentioned above due to pole discrepancy in future. It is also recommended to carry out preventive maintenance of CB regularly so that incident of pole discrepancy can be avoided.


2D. Goa system

2D.1 Substation: 220kV Ponda


2D.1.1: Event Summary:

At 220kV Ponda s/s, 220 kV Mapusa-Ponda 1 and Amona-Ponda 1 tripped due to CT failure of 220 kV Amona-Ponda 2 at Ponda end.

Trippings observed are as follows: o 220 kV Mapusa-Ponda 1 o 220 kV Amona-Ponda 2 o 220 kV Mahalakshmi-Amona

The SLD/Event Report is enclosed at Annexure 2D.1 2D.1.2: Discussion in 135thPCM:

Committee observed that Goa representative was not present in the meeting and therefore the disturbance could not be explained to the sub-committee. The same shall be taken up in the next PCM.

2D.2 Substation: Amona


(134th PCM Agenda item no 2D.1. Goa representative was not present in the 134th PCM meeting and therefore the following disturbance could not be explained to the sub-committee. The same is taken up in the 135th PCM for discussion.) Event Category: GI-2

2D.2.1: Event Summary:

On 19.02.2018 at 06.45 hrs there was a grid incidence at Amona s/s.

R phase LA of 220 kV Amona-Ponda 2 burst at Ponda end and the CB at Amona end did not trip during the event.

This resulted in LBB operation of 220 kV Amona-Ponda 2 and tripping of 220 kV Tillari and Mahalakshmi feeders and ICTs connected to 220 kV Bus 2 at Amona S/s.

Trippings observed are as follows: o 220 kV Tillari-Amona o 220 kV Mahalakshmi-Amona o 220 kV Amona-Ponda 2 o 220/132 kV 100 MVA Amona ICT(BHEL) o 220/132 kV 100 MVA Amona ICT(CGL)

The SLD/Event Report is enclosed at Annexure 2D.2

2D.2.2: Discussion in 135thPCM: Committee observed that Goa representative was not present in the meeting and therefore the disturbance could not be explained to the sub-committee. The same shall be taken up in the next PCM.


2E. Chhattisgarh system

2E.1 Substation: 220/132 KV Bemetra

Date & time: 03.10.2018 at 22:58 hrs. Event Category: GD-1

2E.1.1: Event Summary:

Tripping of 220KV Khedamara – Bemetra resulted in overloading of 220KV Suhela - Bemetra D/C, which eventually got tripped. This has caused the total interruption at 220/132 KV S/s Bemetra and downstream 220/132/33KV & 132/33KV S/s. CSPTL has reported load loss of around 450MW.

Trippings observed are as follows: o 220 kV Khedamara-Bemetra o 220 kV Suhela-Bemetra D/C o 132 kV feeders at Bemetra s/s

The SLD/Event Report is enclosed at Annexure 2E.1

2E.1.2: Discussion in 135thPCM:

At 220KV S/s Bemetara, normally a total load of 300-350 MW aprox is required to feed the load in areas of Bemetara, Mungeli and Kawardha Districts out of which major share is that of agricultural load. Since Mid of September 2018, load requirement went up to 450MW in that area due to increased agricultural load of Kharif crop.

At 220KV S/s Bemetara, normally the major load is shared by 220KV Bemetara - Suhela 1 and 220KV Bemetara-Suhela 2 Lines and about 100MW is shared by 220KV Bemetara-Khedamara Line.

On dated 03.10.2018, due to outage of 500MW generation unit at Korba and one number 400KV 315MVA Transformer at 400KV S/s Bhatapara,PGCIL which ultimately feeds Suhela, the loading on 220KV Bemetara-Khedamara Line increased unexpectedly beyond its overload setting of 650A and resulted in its tripping as the source 220KV Suhela 1 and 220KV Suhela 2 became weak. Further it caused cascading and resulted in total interruption of the area.

NETWORK CONNECTION AND PREFAULT LOADING CONDITIONS


TRIPPING & CHARGING DETAILS AT 220 S/S BEMETARA DATED 03.10.2018


Relay indication a. At 220KV S/S Bemetara :

i. 220KV Suhela 1 tripped on following indication from 220KV Side:- Overcurrent Relay operated 86A operated, 86B operated,

ii.220KV Suhela 2 tripped on following indication from220KV Side:- Overcurrent Relay operated

86A operated, 86B operated, iii.220KV Khedamara tripped on following indication from220KV Side:- Overcurrent Relay operated

86A operated, 86B operated, iv.132KV Kawardha tripped on following indication from 132 KV Side:- Overcurrent Relay operated

86A operated, 86B operated,

b. At 400/220KV S/S Khedamara: The 220KV Khedamara-Bemetara Line tripped on following indication:-

Overcurrent Relay operated. 86A operated, 86B operated,

c. At 220KV S/S Thelkadih : The 220KV Thelkadih -Dhamdha Line tripped on following indication:-

Overcurrent Relay operated 86A operated, 86B operated,

. Remedial Measures:- In order to avoid such trippings, possibility of Second Circuiting of Thelkadih-Bemetara is being explored

The Event report is enclosed as Annexure 2E.1. Committee observed the following: The main reason for tripping of 220kv Suhela I, 220KV Suhela II and

220KV Khedamara in CSPTCL system was due to the increased loading on 220KV Bemetara-Khedamara Line unexpectedly beyond its overload setting of 650A overcurrent at 220KV S/s Bemetera which further lead to interruption at associated 132/33 KV Substations.

MS enquired what actions were taken to avoid similar type incidents in the CSPTCL system.

CSPTCL representative informed that possibility of second circuiting of Thelkadih-Bemetara is being explored to avoid such tripping’s in future.

MS opined the same should be expedited to avoid such tripping’s in future.


2F. Dadra and Nagar Haveli system

2F.1 Substation: 220 kV Khadoli


2F.1.1: Event Summary:

At 220 kV Khadoli S/s, during primary injection testing at CT of 66 kV Khadoli -Khadoli -3, 66 kV side elements tripped on LBB operation.

Trippings observed are as follows: o 220/66 kV 160 MVA Khadoli ICT 1 o 220/66 kV 160 MVA Khadoli ICT 2 o 66 kV feeders at Khadoli s/s

The SLD/Event Report is enclosed at Annexure 2F.1

2F.1.2: Discussion in 135thPCM:

Committee observed that DNH representative was not present in the meeting and therefore the disturbance could not be explained to the sub-committee. The same shall be taken up in the next PCM.

2F.2 Substation: 220/66 kV Bhilosa



220/66 kV Bhilosa ICTs 1&2 tripped on differential protection operation.

Trippings observed are as follows: o 220/66 kV Bhilosa ICT 1 o 220/66 kV Bhilosa ICT 2

The SLD/Event Report is enclosed at Annexure 2F.2

2F.2.2: Discussion in 135thPCM: Committee observed that DNH representative was not present in the meeting and therefore the disturbance could not be explained to the sub-committee. The same shall be taken up in the next PCM.


2F.3 Substation: Kharadpada


(134th PCM Agenda item no 2G.5. DNH representative was not present in the 134th PCM meeting and therefore the following disturbance could not be explained to the sub-committee. The same is taken up in the 135th PCM)


220/66 kV ICTs at Kharadpada substation tripped only on HV side on master trip relay operation and all the 66 kV side elements tripped during the event.

Trippings observed are as follows: o 220/66 kV 160 MVA Kharadpada ICT 1&4 o 220/66 kV 100 MVA Kharadpada ICT 2&3

The SLD/Event Report is enclosed at Annexure 2F.3.

2F.3.2: Discussion in 135thPCM:

Committee observed that DNH representative was not present in the meeting and therefore the disturbance could not be explained to the sub-committee. The same shall be taken up in the next PCM.

2G. Daman and Diu system Nil.


2H. PGCIL systems

2H.1 Substation: 400 kV Kala


2H.1.1: Event Summary:

400 kV Kala bus-2 tripped along with the connected elements on bus bar protection operation during testing of 400 kV bus-1 which was under planned shutdown.

Trippings observed are as follows: o 400 kV Kala-Kudus 2 o 400 kV Kala-Vapi 1 o 400/220 kV 315 MVA Kala ICTs 1&2 o 400 kV 80 MVAR Kala BR

The SLD/Report is enclosed at Annexure 2H.1 2H.1.2: Discussion in 135thPCM: PGCIL representative informed the following;

a) System condition before occurrence was as follows: -

400kV Bus#1 was out of service since 13:07 hrs 05/11/18 for bus interconnection of under construction 400kV ICT#3 Bay.

Further, following feeders were also out of service: - o 400kV Kala Kudus#1: - As this was adjacent bay of ICT#3 o 400kV Vapi Kala#2: - Out of service on Power Regulation o Balance feeders were on Bus#2

b) Tripping detail: -

On 06/11/18 at 12:18 hrs, 400kV Bus#2 got tripped. Due to this, following feeders got tripped (which were on Bus#2): -

o 400kV Vapi Kala#1 o 400kV Kala Kudus#2 o 400kV 315 MVA ICT#1&2 o 400kV 80 MVAr Bus Reactor


SLD of 400kV Kala GIS

Gas SLD ICT Bay


c) Reason of Tripping: - It was found out that tripping of Bus#2 had occurred on SF6 Zone trip

signal (Tripping due to low SF6 pressure for avoiding flashover inside GIS Compartment) of new bay-409 89B Isolator compartment whose gas pressure was marginally low

Herein, it was found out that during shutdown of Bus-1, Busbar relays

were configured for new bays (wherein SF6 gas zone trip logic of both 89-A and 89-B Isolators was present) and configuration was downloaded in the relays so that Bus#1 tripping logic could be tested before taking Bus#1 into service.

After completion of Busbar relay configuration, as in 89B compartment of 409 Bay, SF6 gas pressure was lower than Zone trip level (although it was not physically connected with existing charged Bus-2), hence, Bus#2 tripping logic got satisfied and the connected feeders got tripped.

d) Remedial Measures: - In order to avoid such trippings, GIS sites have been instructed to

ensure integration activities only in accordance with SF6 gas zone tripping logic and to take utmost precaution.

The Event report is enclosed as Annexure 2H.1.

e) Committee observed the following:

Committee observed that main reason for the operation of bus bar

protection and tripping of all the lines connected to bus 2 was due to the SF6 gas pressure was in 89B compartment of 409 Bay, was lower than Zone trip level (although it was not physically connected with existing charged Bus-2), thus Bus2 tripping logic got satisfied and the connected feeders got tripped.

MS enquired whether the standard operating procedure was followed during the integration of new bays into the system and also expressed concern over these types of incidents which were result of not following the SOP during testing and integration of new elements into system.

MS requested all the constituents to follow the SOP during the testing of new elements and integration of new elements into system so that similar type of incidents can be avoided in future.


2H.2 Substation: 765/400 kV Solapur

Date & time: 03.12.2018 at 10:26 hrs.



At 765/400 kV Solapur s/s, B-Phase Inductive Voltage Transformer(IVT) of 400KV/38.5KV Coupling transformer failed (got burnt) and due to the fumes from blasting of IVT, 400KV BUS 1 and 765KV/400 kV ICT2 tripped.

Trippings observed are as follows: o 400 kV Solapur Bus 1 o 765 kV/400kV Solapur ICT-II o 2X 150 MVAR Solapur STATCOM o 400 kV/38.5kV Solapur STATCOM Coupling Transformer

2H.2.2: Discussion in 135thPCM:

PGCIL representative informed the following;

On dated 03.12.2018 (10:27:57), 400KV Bph IVT connected on HV side of coupling transformer was failed(blasted).

The following elements at Solapur SS tripped/Isolated due to failure of IVT.

(i) 400/38.5KV Coupling transformer. (ii) 400KV BUS#1 (Tripped due to smoke of blasted IVT) (iii)765KV/400KV ICT#2 (Tripped due to smoke of blasted IVT)

Sequence of events after blasting of Bph IVT are as follows: (i) 400/38.5KV Coupling transformer tripped on differential

protection at10:26:57:198 Hrs (ii) Consequently, due to the fumes/smoke from blasting of Bph

IVT, o 400KV BUS#1 was got tripped at 10:26:57:915 on bus bar

differential protection. o 765KV/400KV ICT#2 was tripped on differential protection

at 10:26:59:703


Location of failed IVT


Committee observed the following:

Committee observed that main cause of tripping of 400KV BUS#1, 765KV/400KV ICT#2 and 400/38.5KV Coupling transformer at Solapur SS on differential protection was due to failure of 400KV Bph IVT connected on HV side of coupling transformer.

Differential protection operation of 400KV BUS#1, 765KV/400KV ICT#2 and 400/38.5KV Coupling transformer were found in order.

MS opined that Solapur SS was a newly constructed SS and this type of incidents are not expected from a newly constructed SS.

MS enquired about the results of the tests which were done on the failed B phase IVT.

PGCIL representative informed that testing was done on the IVT and results were satisfactory.

MS informed that the root cause of blast of Bph IVTs needs to be investigated by PGCIL and a copy of investigation report need to be submitted to this committee for further analysis.


2H.3 Substation: 765/400 kV Dharamjaigarh

Date & time: 07.12.2018 at 11:31 hrs.



At 765/400 kV Dharamjaigarh s/s,Bus bar protection of 400kV Bus 2 operated while conducting protection testing of 400 kV Bus 1 and resulted in tripping of 765/400 kV 1500 MVA Dharamjaigarh ICTs 1&2. Due to the tripping, power flow in 400 kV Dharamjaigarh-Balco D/C became zero and Balco system got islanded.

At 11:46hrs. after charging one of the 765kV/400kV ICTs at Dharamjaigarh, 400kV Bus 2 at Dharamjaigarh was charged and 400kV Bus 2 at BALCO tripped on bus bar protection on R phase fault resulting in tripping of 400kV Bus Coupler, ICT 1 & ICT 3 at BALCO.

Trippings observed are as follows: o 765/400 kV 1500 MVA Dharamjaigarh ICTs 1&2 o 400 kV Dharamjaigarh-Balco D/C o 400/220 kV 315 MVA Balco ICTs 1&3



The following elements at Dharamjaygarh SS tripped from 765 kV side during the 400 kV Bus-1 Busbar protection testing on 7.12.2018 .

o 765/400kV ,1500 MVA ICT -1 o 765/400kV, 1500 MVA ICT -2 o 400 kV BALCO 1&2 feeders tripped from BALCO end only.

400 kV Bus-1 shutdown availed by opening 414,417, 420 & 423 CB’s For 400 kV Bus-1 Bus bar protection testing – 414 bay main1 PU

Secondary Current injection ramped up to set level of tripping i.e. 1.2A and BB tripping observed at CUA. 400KV Bus Zone 1 Operated correctly.

Immediately it was observed that both ICT 1 & 2 tripped from 765KV Side on opening of HV Main & Tie CBs on operation of main and Tie bay 86 A & B trip relays.

Further, it was observed that all 400KV CBs connected to BUS 2 are in closed position only and which is also correct.

After tripping of both the ICTs, islanding scheme of BALCO operated and both 400 kV BALCO feeders tripped from BALCO end resulted into Zero Voltage on 400KV BUS 2. BALCO system separated with their own load and generating units.

Reason for inadvertent tripping of both ICT 1 & 2 from 765KV Side on opening of HV Main & Tie CBs on operation of main and Tie bay 86 A & B trip relays.


ICT’s 765 kV side main and Tie bay’s – 86A and 86B relays operated on receipt of Inter trip signal from 400KV side (ATA panel) .

Inter trip signal was originated from 420 & 423 bays PU’s of Bus 1 from output contacts – RL 13, 14 of respective PU’s.

Output contacts - RL13, 14 were wrongly configured in PSL for operation on Bus bar protection.

SLD of 400 KV Dharamjaygarh SS as follows:-

SLD of 765 KV Dharamjaygarh SS as follows:-


a) Corrective actions Recommended

For mentioned case-On operation of 400KV Bus Bar protection -inter trip signal to be sent only if second breaker connected to other bus is in Open condition. OR

For In Half Dia Inter trip signal to be removed from PSL for Bus Bar protection operation and should be sent only for LBB operation.

The Event report is enclosed as Annexure 2H.3. b) Committee observed the following:

MS opined that before Bus bar protection testing, Scheme drawings needs to be checked in details.

MS opined that all relay settings, PSL/Relay logics/Input contacts/Output contacts assignments needs to be checked in details before proceeding for any testing activities.


2H.4 Substation: 400/220 kV Bhattapara

Date & time: 11.12.2018 at 04:03 hrs.



At 400/220 kV Bhattapara s/s, Y phase CT of 400 kV Bhilai feeder failed and resulted in tripping of all Main bays connected to 400 kV Bus 1. Since the fault was fed from the other side of the line, LBB of tie bay operated and DT was sent to other end resuting in tripping of 400 kV Bhattapara-Bhilai.

Trippings observed are as follows: o 400 kV Bhatapara Bus 1 o 400 kV Bhatapara-Bhilai



On 11.12.2018 at 04.03.36 Hrs. Main Bay Y-phase CT (404) of 400 kV Bhilai circuit failed resulting in Y-phase to earth fault. This caused tripping of Main breakers (403, 404,408) connected to 400 kV Bus-1 on operation.

Busbar protection of 400 kV Bus -I operated correctly on Y-phase to earth fault resulting in tripping of all the main breakers connected to Bus-I (403,404,408). Bus Fault current was 11 KA.

However, as the fault was feeding from remote end, LBB of 404 CB operated resulting in tripping of Tie breaker (405) of Bhilai line at Bhatapara and tripping of Bhilai circuit at Bhilai end on direct trip received signal. Fault current on Korba and Bhilai line was 3.49 KA and 4.35 KA respectively. Total fault contribution from ICT I & II was 3.3 kA on HV side.


Restoration details o 400 kV Bus-I charged at 06.06 hrs. o 400 kV Bhilai circuit charged at 06.18 hrs.



Operation of Bus Bar protection and LBB was in order. Main-I & Main-II Distance protection of Bhilai line has also sensed

this fault in reverse direction (reverse zone start) which was also in order

2H.5 Substation: Bilaspur

Date & time: 21.12.2018 at 10:52 hrs.


2H.5.1: Event Summary At Bilaspur s/s, tie bay of 765 kV Sipat-Bilaspur 3 went to SF6 lockout

condition due to SF6 leakage. While opening the 89 B isolator, sparking was observed in Y phase and 765 kV Bus 2 and all the main bays tripped on Bus bar protection operation. Since the SIpat 2 circuit was connected only to Bus 2 through main bay,it also tripped.

Trippings observed are as follows: o 7655 kV Bilaspur Bus 2 o 765 kV Sipat-Bilaspur 2



The following elements at Bilaspur SS tripped while isolating CB under SF6 lockout on21.12.2018 .

A. 765 kV Bus-2 B. 765 kV Sipat-2

On 21.12.2018,765 kV Tie CB of 765 kV Sipat-3 and Future bay SF6 lockout alarm appeared.

As 765 kV Bus-2 tripping leads to isolation of 765 kV Sipat-2 heavily loaded generation connected line connected through 765 kV Bus-2 main breaker only, hence for avoiding isolation of 765 kV Sipat-2 heavily loaded generation connected line, Instead of tripping 765 kV Bus-2, following operation sequence was adopted by site for isolating CB under SF6 lockout-

a. Sipat -3 line Shutdown applied for load isolation. PLCC channel kept out to avoid DT receive and LBB operation at Bilaspur end. Sipat-3 line tripped from Sipat end and line load reduced to charging current of line(22 kM)

b. 701 Sipat-3 main breaker opened at Bilaspur SS –Locally.


c. 702 89B Bus-2 side isolator opened for isolating breaker under SF6 lockout-Locally.

But, while interrupting line charging current by opening 702 89B Bus-2 side isolator, heavy sparking occurred at isolator and arc formed in 765 kV BUS-2 vicinity. Hence, 765 kV Bus-2 got tripped on Busbar protection operation and 765 kV Sipat-2 line got isolated.


a) Analysis

As per Technical circular 03/2017 dated 9.05.2017 regarding guidelines to check for single phasing while taking outage, for isolation of above mentioned 702 half dia future bay Tie breaker under stuck condition. Following is sequence of operation-

a. Tripping of all main bays CB’s connected to Bus-2 needs to be done first.

b. After Bus-2 isolation, 701 Sipat-3 main breaker at Bilaspur SS needs to be opened.

c. After ensuring current zero in 702 bay CB, 702 bay 89-A and 89B isolator needs to be opened.

b) Lesson learned from occurrence

Before performing isolator operations of bay with Stuck Breaker or Breaker under lockout following needs to be ensured-

Following of operation guidelines mentioned in Technical circular 03/2017 dated 9.05.2017 for ensuring current Zero in bay with stuck breaker. After ensuring current zero, isolator opening operation can be performed.

OR

If majority load is affected while implementation of Technical circular 03/2017 dated 9.05.2017 for ensuring current Zero in bay with stuck breaker, In such cases, on load isolator operation can be performed by creating parallel path for stuck breaker bay current. But before performing on load isolator operation , consent needs to be taken from Regional –AM department.

c) Action proposed/taken to avoid such occurrences in future: Regular sensitization of Site/RTAMC operation

staff/Engineers/JE’s/Technicians for following of correct operating procedure as per approved guidelines through training/discussions etc.

On dated 21.12.2018, Technical circular 03/2017 dated 9.05.2017 regarding guidelines to check for single phasing while taking outage discussed among WR-1 JE’s and RTAMC staff during Protection training of JE’s at RHQ, Nagpur.


d) Committee observed the following: Opening of 701 Sipat-3 main breaker before opening of 702 89B Bus-2

side isolator of breaker under lockout. If 701 Sipat-3 main breaker was


kept under closed condition before opening 89 B Isolator ,After opening of 702 89B Bus-2 side isolator , Heavy arcing may not be formed in BUS-2 vicinity , as 702 bay current will take parallel path through 701 Sipat-3 main breaker.

PGCIL representative informed that there is history of frequent SF6 gas leakage in recently commissioned ABB make breakers in WR-1 region which leads to this incidence of SF6 breaker lockout.

MS opined that regular sensitization of Site operation staff/Engineers/JE’s/Technicians for following of correct operating procedure as per approved guidelines through training/discussions etc need to be followed.

2H.6 Substation: HVDC Champa-Kurukshetra pole 1 and 2

Date & time: 03.06.2018 at 11.02 hrs.


(134th PCM Agenda item no 2E.1. HVDC Champa PGCIL representative was not present in the 134th PCM meeting and therefore the following disturbances could not be explained to the sub-committee. The same is taken up in the 135th PCM.)


On 03.06.2018 at 11.02 hrs there was a grid incidence at HVDC Champa-Kurukshetra s/s.

800 kV HVDC Champa-Kurukshetra pole 2 blocked due to High Voltage High Speed CB failure and at the same time Pole 1 also blocked due to the trip command received from Pole 2.

Trippings observed are as follows: o +/-800 kV HVDC Champa-Kurukshetra Pole 1 o +/-800 kV HVDC Champa-Kurukshetra Pole 2



INCIDENCE REPORT ON FAILURE OF POLE-II HVHS CIRCUIT BREAKER

± 800kV, 3000MW Champa –Kurukshetra Link ,Pole1 & Pole2 running at 750MW each. With Bipole power flow of 1500MW

Initial Conditions: Operation mode : Bipole – with DMR1(DMR 2 is out) Power Level : 1500 MW Lane in control : Bipole level – Lane 1 active and Lane 2 standby : Pole 2 level – Lane 2 active and Lane 1 standby


Pole 1 level – Lane 1 active and Lane 2 standby Master control : Champa Filters in service :11,12,21,31,33 Filters (3A+1B+1C) Bay in Service : 463&464 Transformer Bays in Pole1 465 & 466 Transformer bays in Pole-2

Sequence of SER Events: on dated 03.06.2018

1. 10:58:37:711 A P2 P2A HVDC Circuit Breaker Q89903 Closed (Status) Cleared

(Breaker opened. Physically found pole is found open and another pole in closed position as per indication at site after the incident)

2. 10:58:37:765 A P2 L1/2 Main ½ HV Line switch Reclose

Present (Breaker opened but unable to quench DC current so controls issued the reclose command to save the breaker)

3. 10:58:37:765 A P2 L1/2 Main ½ HV Line switch fail to commutate current Present

4. 10:59:12:560 A P2 L1/2 Main ½ HV Line switch Reclose Cleared

5. 10:59:13:601 A P2 L1/2 Main ½ HV Line switch Reclose Present

(After this alarm blast observed in Pole-2 DC yard)After the incident during physical observation in DC yard found smoke in Pole-2 HVHS breaker.)

6. 11:02:55:569 A Pole-I&II Pole is blocked

Present Fault analysis details:

Bipole blocked at 11:02:55:569 Hrs Pole-2 blocked at 11:02 Hrs due to HVHS reclose protection. Pole-1 Blocked may be due to Block from Other pole as per protection strategy. But no alarm observed in SER related to Pole-1. (Ref:ALSTOMCKL-05007 Document)

Pole-II under shutdown condition.Replacement of Breaker is going on. Pole-1 Deblocked at 12:08 Hrs.


The Damaged Breaker Photos:

The physical location of HVHS:

The Event report and EL and DR’s submitted by PGCIL is enclosed as Annexure 2H.6.

Committee noted.


2H.7 Substation: HVDC Champa-Kurukshetra pole 1 and 2

Date & time: 15.06.2018 at 14.15 hrs. (134th PCM Agenda item no 2E.2)



On 15.06.2018 at 14.15 hrs there was a grid incidence at HVDC Champa-Kurukshetra s/s.

800 kV HVDC Champa-Kurukshetra Bi-pole tripped on Filter control blocking due to filter power limit alarm at Champa end.

Trippings observed are as follows: o +/-800 kV HVDC Champa-Kurukshetra Pole 1 o +/-800 kV HVDC Champa-Kurukshetra Pole 2



• Bipole Blocked due to toggling of Bipole Control Block Bit during Changeover from One Lane to Other Lane.

Committee noted.

2H.8 Substation: Champa HVDC station


Event Category: GI-2 2H.8.1: Event Summary:

On 02.02.2018 at 10.38 hrs there was a grid incidence at Champa HVDC station.

Due to commutation failure both HVDC poles of Champa Kurukshetra tripped.

Trippings observed are as follows: o 800 kV HVDC Champa(WR) - Kurukshetra(NR) line -2 o 800 kV HVDC Champa(WR) - Kurukshetra(NR) line -1

2H.8.2: Discussion in 135thPCM: PGCIL representative informed the following;

• Commutation failure at Kurukshetra is getting detected as DC Line fault.

• DC LF detection time settings has been updated as per site conditions.

The Event report is enclosed as Annexure 2H.8. Committee noted.


2H.9 Substation: 400 kV Champa




On 07.08.2018 at 14.17hrs there was a grid incidence at 400 kV Champa Substation.

Due to PLCC problem at Champa end DT was sent to KSK end and 400 kV Champa-KSK 4 tripped.

KSK units 2&4 tripped on Torsional Stress Relay operation (TSR) and under frequency protection respectively.

Trippings observed are as follows: o 400 kV Champa-KSK 4 o 600 MW KSK Unit 2 o 600 MW KSK Unit 4 o KSK Station transformer 1&2

2H.9.2: Discussion in 135thPCM: Committee observed that KSK representative was left before the completion of meeting and therefore the disturbance could not be explained to the sub-committee. PCM advised to KSK to be present in PCM for discussion of incidents related to their assets. Due to absence of KSK representative, the incident shall be taken up in the next PCM for discussion. The Event report is enclosed as Annexure 2H.9.

2H.10 Substation: ±800 kV HVDC Champa-Kurukshetra terminals



On 17.08.2018 at 16.39 hrs there was a grid incidence at ±800 kV HVDC Champa-Kurukshetra terminals.

±800 kV HVDC Champa-Kurukshetra Bipole tripped due to commutation failure at Kurukshetra end.Trippings observed are as follows:

o ±800 kV HVDC Champa-Kurukshetra Pole 1 o ±800 kV HVDC Champa-Kurukshetra Pole 2


Commutation failure at Kurukshetra is getting detected as DC Line fault.

DC LF detection time settings has been updated as per site conditions.







±800 kV HVDC Champa Kurukshetra Bi pole tripped due to commutation failure at Kurukshetra end.

Trippings observed are as follows:

o ±800 kV HVDC Champa-Kurukshetra Pole 1 o ±800 kV HVDC Champa-Kurukshetra Pole 2



Commutation failure at Kurukshetra is getting detected as DC Line fault. DC LF detection time settings has been updated as per site conditions.


Committee noted.





±800 kV HVDC Champa-Kurukshetra Pole 2 was blocked for testing purpose. At the same time Pole 1 also blocked on Control malfunction.

Trippings observed are as follows: o ±800 kV HVDC Champa-Kurukshetra Pole 1 o ±800 kV HVDC Champa-Kurukshetra Pole 2


PGCIL representative informed the following; During Software testing Pole-1 Tripped.






±800 kV HVDC Champa Kurukshetra Bi pole tripped due to DC earth fault in auxillary DC panel at Champa end.



PGCIL representative informed the following; • Due to DC earth fault in system, BCU got restart. This resulted

in External block command to controls. • DC Earth fault has been identified in a faulty cable. It is rectified

by replacement of cable. • To avoid repetition of above mentioned false tripping of Pole/ bi-

pole, all digital input signals for "external block" logic configured in the available protection relays (like-MICOM P 643, P 141 already installed in pole DIA / converter transformers protection) in place of BCU for better reliability / security. (Ref:Trip2)





±800 kV HVDC Champa Kurukshetra Bi pole tripped on Filter control blocking due to Filter Power limit.



• Bipole blocked while changing RPC from Automatic to Manual mode for switching of filters at Champa.

• Bipole blocked due to persisting alarm in controls. Provision for re-setting of all type of protections latched (control & protection both) clearance from HMI has been requested to GE.

• Till then instructions were given to operator to check and reset the protections manually in Controls software.



2I. NTPC systems

2I.1 Substation: Vindhyachal

Date & time: 23.07.2018 at 19.57 hrs. (134th PCM Agenda item no 2F.1)


(134th PCM Agenda item no 2F.1. NTPC representative was not present in the 134th PCM meeting and therefore the following disturbances could not be explained to the sub-committee. The same is taken up in the 135th PCM)

2I.1.1: Event Summary:

On 23.07.2018 at 19.57 hrsthere was a grid incidence at Vindhyachal S/s.

At Vindhyachal S/s, all the 132 kV elements tripped due to the delayed clearance of fault on 132 kV Vindhyachal-Waidhan.

Trippings observed are as follows: o 400/132 kV 200MVA Vindhyachal ICTs 1,2&3 o 132 kV Vindhyachal-Morwa o 132 kV Vindhyachal-Waidhan o 132 kV Morwa-Bina o 132 kvMorwa-Anpara o +/- 500 kV HVDC Vindhyachal pole-1

2I.1.2: Discussion in 135thPCM:

NTPC representative informed the following;

a) Relays / protection acted:

(i) 132 KV V-Waidhan line # 1(on Bus-1): Back up Directional O/C -R, Y, B phase, Distance protection operated.

(ii) 400 KV ICT # 2: Tripped on HV WTI trip (19:57:40.123) (iii)132 KV ICT # 2(on Bus-1): Tripped on Remote trip command (Due to

Opening of HV side Breaker) (iv) 400 KV ICT # 1: Tripped on Back up Directional O/C -B phase

protection. (19:57:40.862) (v) 132 KV ICT # 1(on Bus-2): Tripped on Remote trip command (Due to

Opening of HV side Breaker) (vi) 400 KV ICT # 3: Tripped on Back up Directional O/C- B phase

Protection. (vii) 132 KV ICT # 3(on Bus-3): Tripped on Remote trip command (Due

to Opening of HV side Breaker) (19:57:41.008)

b) Root Cause Analysis


• ICT-1, ICT-2 & ICT-3 were tripped on backup over current protection, which leads to Blackout of complete 132 KV switchyard system. During site inspection, Bus side conductor of Bus Isolator (B phase) of V-Waidhan line# 2 found snapped. Conductor was hanging from the Main Bus-1 and touching to ground which generated fault and finally All ICTs got tripped along with Waidhan#1 and Waidhan#2 on backup overcurrent protection.

• Under Normalization process, Faulty Bus -1 isolated from other Buses. Then Bus-2 and Bus-3 charged through ICT-1 & ICT-3 and connected feeders taken in service. After removal of broken conductor, Bus-1 made charged and feeders taken in service except: V-Waidhan line#2 and Colony Transformer (whose Breaker air pipe line got damaged due to broken conductor).

• Ultimately Bus-1 charged and all feeders of that Bus taken in service.

• According to DR report of 400 KV ICT-3 Relay, Maximum fault current was 2.3 kA and fault duration was approx. 2.0 sec. (DR report attached)

ICT#1BAY#1

ST#3BAY#2

ST#5BAY#3

BU

S T

RA

NS

FE

R#

1B

AY

#4

MAIN BUS#2

TRANSFER BUS

BU

S T

RA

NS

FE

R#

2B

AY

#1

0

BUS SECTION#1BAY#7

SPARE BAY#5

ST#1BAY#6

ST#2 BAY#8

ST#4BAY#9

V-W L#1BAY#11

V-W L#2BAY#12

RIHAND LINE BAY#14

SINGRAULILINE BAY#15

ICT#2BAY#16

CPT 132/11kVBAY#13

BUS SECTION#2BAY#17

IBT#3BAY#19

ST#6BAY#18

MISC. XMERBAY#20

TR

AN

SFE

R B

AY

BA

Y#

21

132 KV STAGE#1&2 SWITCHYARD BAY DIAGRAM

MAIN BUS#1MAIN BUS#3

132/11kV


c) EVENT LOGGER

• 19:57:39.691 # 8 BUS CVT METERING CORE FUSE FAIL • A 19:57:39.724 # 147 STATION TRANSF.#5 COOLER CONTROL SUPPLY FAIL

ALARM • A 19:57:39.747 # 51 STATION TRANSF. #6 COOLER CONTROL SUPPLY FAIL

ALARM • A 19:57:39.809 # 8 BUS CVT METERING CORE FUSE FAIL • A 19:57:40.123 # 463 ICT-2 TR. WTI (HV) TRIP • N 19:57:40.134 # 463 ICT-2 TR. WTI (HV) TRIP • A 19:57:40.153 # 434 1152 OPERATED • A 19:57:40.285 # 446 1152 LOW AIR PRESSURE • N 19:57:40.325 # 446 1152 LOW AIR PRESSURE • A 19:57:40.591 # 444 1152 TC-2 FAULTY • A 19:57:40.862 # 422 ICT-1 BACK UP TRIP • A 19:57:40.894 # 416 ICT-1 GROUP-B TRIP • A 19:57:40.901 # 415 ICT-1 GROUP-A TRIP • A 19:57:40.988 # 412 1752 LOW AIR PRESSURE • N 19:57:41.008 # 108 IBT#3 CB 1952 ON • A 19:57:41.024 # 139 STATION TRANSF.#5 COOLER 415V AC FAIL ALARM • A 19:57:41.033 # 99 IBT #3 CB 1952 AUTO TRIP • N 19:57:41.035 # 422 ICT-1 BACK UP TRIP • N 19:57:41.158 # 416 ICT-1 GROUP-B TRIP • N 19:57:41.177 # 415 ICT-1 GROUP-A TRIP • A 19:57:47.758 # 442 SEQ. OPENING IMPULSE TO 1189L • NTPC VINDHYACHAL 1 23 Jul 2018 19:58:16 m • N 19:58:16.130 # 412 1752 LOW AIR PRESSURE • N 19:58:24.760 # 444 1152 TC-2 FAULTY • A 19:58:47.544 # 444 1152 TC-2 FAULTY • 23 Jul 2018 20:00:01 m • N 20:18:31.588 # 72 STATION TRANSF. #6 CB 1852 ON • N 20:18:40.260 # 168 STATION TRANSF.#5 CB 352 OFF • N 20:20:11.850 # 14 BUS SECTION CB 1752 ON • N 20:24:24.919 # 15 BUS SECTION ISO 1789A ON

The Event report is enclosed as Annexure 2I.1.


• Primary cause of this blackout was broken conductor of Waidhan#2 line. Bus bar Differential protection (RADSS relay) for Bus-1 was supposed to operate in this fault, where fault is located towards the Bus. Due to some fault in static busbar relay, fault was not cleared instantaneously and extended to other Buses. And Ultimately ICT-1 and 3 got tripped on Back up over current protections, which lead to Blackout of Complete 132 KV Switchyard system.

• NTPC representative informed about the remedial action taken by them after occurrence of the incident as follows:

o Fault in Bus bar relay rectified during testing. o Replacement of complete Protection relays are planned under

Switchyard Mega R&M package, which has already been awarded to M/s Siemens Ltd and being done on utmost priority.

o Single GPS system for Time synchronization of all SER of 132 kV Switchyard will be commissioned under R&M.


2I.2 Substation: 400kV Vindhyachal

Date & time: 27.09.2018 at 12.21 hrs. (134th PCM Agenda item no 2F.2)


(134th PCM Agenda item no 2F.2. NTPC representative was not present in the 134th PCM meeting and therefore the following disturbances could not be explained to the sub-committee. The same is taken up in the 135th PCM)

2I.2.1: Event Summary:

At 400kV Vindhyachal, to attend trip coil alarm which appeared on Main bay of Vindhyachal Unit 8, the unit was transferred to transfer bay.

While transferring Unit 8 from main Bus 4 to transfer bus, bus bar protection operated and all the elements connected to the main bus 4 tripped.

Trippings observed are as follows: o 500 MW Vindhyachal Unit 8 o 400 kV Vindhyachal-Korbackt 2 o 400 kV Vindhyachal-Satna ckt 2 o 400 kV Vindhyachal-Jabalpur ckt 2

2I.1.2: Discussion in 135thPCM:

NTPC representative informed the following;

• Unit was running normal at 495 MW load. Trip circuit-2 faulty alarm was appearing and resetting at night. Again, alarm appeared on 09.15 hrs. For attending the fault of trip circuit of main breaker, Unit was taken on transfer bus.

• Transfer breaker was closed on 12.18 hrs in parallel with main breaker. Main breaker opened through manual command from UCB at 12.21 hrs and unit tripped on GBE (Generator Back Energizing) protection.

• The condition for GBE is (a)-main breaker open (b)-Transfer Breaker open and (c) - current in Line. Since transfer breaker was closed, hence GBE relay should not pick up.

• But the close feedback contact of transfer breaker malfunction causing operation of GBE protection.

• Afterwards BFR protection operated (due to initiation from GBE Trip relay and current),which initiated Bus -4 trip command and finally Bus-4 feeders V-Jab#2,V-Satna#2 & V-Korba#2 line got tripped.

a) SER

NTPC LIMITED-VINDHYACHAL


Plant Name : 400/220KV SWITCHYARD Sr. No. SER Name SER Status Date and Time Point No. Legend

• 1 NTPC Vindhyanchal STG-II SER01 Alarm 9/27/2018 03:12:39:862 180 GT#8 TBC CB TRIP CKT-1/2 FAULTY

• 2 NTPC Vindhyanchal STG-II SER01 Normal 9/27/2018 03:14:40:890 180 GT#8 TBC CB TRIP CKT-1/2 FAULTY


• 4 NTPC Vindhyanchal STG-II SER01 Normal 9/27/2018 03:14:40:952 180 GT#8 TBC CB TRIP CKT-1/2 FAULTY



• 7 NTPC Vindhyanchal STG-II SER01 Alarm 9/27/2018 11:31:36:696 346 400KV TBC(BAY22) ISOL 2289T CLOSE

• 8 NTPC Vindhyanchal STG-II SER01 Alarm 9/27/2018 11:33:24:197 344 400 KV TBC(BAY22)ISOL 2289B CLOSE

• 9 NTPC Vindhyanchal STG-II SER01 Alarm 9/27/2018 12:18:04:223 342 400 KV TBC CB(2252)B-PH CLOSE

• 10 NTPC Vindhyanchal STG-II SER01 Alarm 9/27/2018 12:18:04:227 340 400 KV TBC CB(2252)R-PH CLOSE

• 11 NTPC Vindhyanchal STG-II SER01 Alarm 9/27/2018 12:18:04:234 341 400 KV TBC CB(2252)Y-PH CLOSE

• 12 NTPC Vindhyanchal STG-II SER01 Alarm 9/27/2018 12:21:01:513 351 GT#8 Y PH CKT Breaker open

• 13 NTPC Vindhyanchal STG-II SER01 Alarm 9/27/2018 12:21:01:514 350 GT#8 R PH CKT BreakeR open

• 14 NTPC Vindhyanchal STG-II SER01 Alarm 9/27/2018 12:21:01:521 352 GT#8 B PH CKT BreakeR open

• 15 NTPC Vindhyanchal STG-II SER01 Alarm 9/27/2018 12:21:02:196 192 GT#8 ACCIDENTAL BACK ENERGISATION RELAY OPTD

• 16 NTPC Vindhyanchal STG-II SER01 Alarm 9/27/2018 12:21:02:452 181 GT#8 BFR OPTD

• 17 NTPC Vindhyanchal STG-II SER01 Normal 9/27/2018 12:21:02:473 342 400 KV TBC CB(2252)B-PH OPEN

• 18 NTPC Vindhyanchal STG-II SER01 Normal 9/27/2018 12:21:02:481 340 400 KV TBC CB(2252)R-PH OPEN

• 19 NTPC Vindhyanchal STG-II SER01 Normal 9/27/2018 12:21:02:481 341 400 KV TBC CB(2252)Y-PH OPEN

• 20 NTPC Vindhyanchal STG-II SER01 Alarm 9/27/2018 12:21:02:493 236 VS#2 R POLE CKT BKR TRIP

• 21 NTPC Vindhyanchal STG-II SER01 Alarm 9/27/2018 12:21:02:493 237 VS#2 Y POLE CKT BKR TRIP

• 22 NTPC Vindhyanchal STG-II SER01 Alarm 9/27/2018 12:21:02:495 238 VS#2 B POLE CKT BKR TRIP

• 23 NTPC Vindhyanchal STG-II SER01 Normal 9/27/2018 12:21:02:505 192 GT#8 ACCIDENTAL BACK ENERGISATION RELAY OPTD

• 24 NTPC Vindhyanchal STG-II SER01 Normal 9/27/2018 12:21:02:506 181 GT#8 BFR OPTD

• 25 NTPC Vindhyanchal STG-II SER01 Alarm 9/27/2018 12:21:02:514 137 SATNA2 GROUP A 3 PH TRIP

• 26 NTPC Vindhyanchal STG-II SER01 Normal 9/27/2018 14:35:44:446 350 GT#8 R PH CKT BKR closed

• 27 NTPC Vindhyanchal STG-II SER01 Normal 9/27/2018 14:35:44:448 351 GT#8 Y PH CKT BKR closed

• 28 NTPC Vindhyanchal STG-II SER01 Normal 9/27/2018 14:35:44:465 352 GT#8 B PH CKT BreakeR closed

• 29 NTPC Vindhyanchal STG-II SER01 Normal 9/27/2018 14:38:27:205 344 400 KV TBC(BAY22)ISOL 2289B OPEN

• 30 NTPC Vindhyanchal STG-II SER01 Normal 9/27/2018 14:41:28:789 346 400KV TBC(BAY22) ISOL 2289T OPEN


b) SLD

c) Remedial action done

• Transfer Breaker contact replaced. • Unit#08 Main breaker to TBC Breaker changeover checked during

Overhauling. • Main Breaker Trip circuit contactor replaced.

The Event report is enclosed as Annexure 2I.2.


• Main reason for GBE (Generator Back Energizing) protection operation was due to satisfying all the conditions for the operation of GBE, which are (a)-main breaker open (b)-Transfer Breaker open and (c) - current in Line.

• In this incident transfer breaker was closed, hence GBE relay should not pick up. But the close feedback contact of transfer breaker malfunction causing operation of GBE protection which resulted into BFR protection operation and tripping of Bus-4 feeders V-Jab#2,V-Satna#2 & V-Korba#2 line.

• NTPC briefed about the remedial actions taken after the incident. • MS opined that proper maintenance of CB need to be done to avoid

such type of incidents.


2J. IPP systems

2J.1 Substation: Blackout at Sardar Sarovar Project (SSP)/ NCA

Date & time: 16.07.2018 at 4.11 hrs. (134th PCM Agenda item no 2G.1)

Event Category: GD-1 (134th PCM Agenda item no 2G.1. SSP representative was not present in the meeting and therefore the following disturbance could not be explained to the sub-committee. The same is taken up in the 135th PCM.)

2J.1.1: Event Summary:

On 16.07.2018 at 04.11 hrsthere was a grid incidence at Sardar Sarovar Project (SSP) s/s.

400kV SSP-Asoj, Rajgarh-SSP D/C and SSP-Dhule-2 were opened to control over voltage.

400 kV SSP-Kasor and 400 kV SSP-Dhule 1 tripped at SSP on Over Voltage causing blackout at SSP.

There was no generation at SSP. Tripping’s observed are as follows:

o 400 kV SSP- Kasor o 400 kV SSP-Dhule 1

2J.1.2: Discussion in 135thPCM:

NCA representative informed the following;

Brief of Hydro (Water) & Elect. Power parameters

• Dam water Level was 110.43 mtr on Dt. 16.07.18- which was below MDDL(Minimum Draw Down Level) since Feb-2018. (Due to consecutive bad monsoon seasons)

• Due to water level below MDDL, no unit of SSP was running in Generation/condenser mode.

• Following lines were in service.

o 400KV SSP- Rajgarh-2 Line. o 400KV SSP- Kasor Line. o 400KV SSP- Dhule-1 Line.

• On Dt. 16.07.18 Following lines were ready for service which were

made off and to maintain voltage by WRLDC/NCA as under.... o 400KV SSP-Rajgarh-1 line. (@22:18, 09.07.18) o 400KV SSP- Asoj line. (@2:47, 15.07.18) o 400KV SSP- Dhule-2 line. (@17:14, 07.07.18)


• On Dt. 16.07.18, Grid voltage was increased rapidly and same was informed to WRLDC at 03.10 hrs by SSP-operation wing.

• At time 03.10.04 am hrs. 400KV SSP- Rajgarh-2 line was tripped on overvoltage.


• On Dt. 16.07.18 At 03.30 am, system voltage was 436 KV at RBPH end and only

2 (Two lines) were in service. 1.400KV SSP- Kasor and 2.400KV SSP-Dhule-1

• Informed to WRLDC/NCA/SLDC by SSP-operation about the voltage conditions at SSP End and only 2 (Two) lines in service.

• Within ½ hour, on Dt. 16.07.18 at 04.11 am these two lines Tripped on Overvoltage • and Blackout at SSP End occurred. • Blackout at SSP -informed to NCA/WRLDC & SLDC. • At 04.29hrs. 400KV SSP-Raj-2 line made ‘on’, as per NCA code

no.1429 but again line tripped on Overvoltage. DR report are attached.

• At 04.40 Hrs. SSP- Kasor line made ‘on’ vide NCA code no. 1430 from opposite end but could not be made ‘ON’ at SSP end due to breaker mechanical problem at SSP end.

• At 04.48 Hrs. SSP- Asoj line made ‘on’ as per NCA code no. 1431 and line stood charged on SSP alone Bus and Supply restored at SSP-RBPH.

• At 07.40Hrs. 400KV SSP- Kasor line synchronized as per NCA code no.1432.

• At 08.43 hrs. 400KV SSP- Dhule-1line synchronized as per NCA code no.1437.

• NCA representative stated that after considering depleting Dam water level below MDDL of SSP, the possible following remedial measures were suggested.

• First the shortest line has to be taken in to services. (Here in case instead of Raj-2 & Kasor, it could be Asoj - the shortest line)

• At least more than 2 lines are to be kept in service at SSP to avoid formation of single ckt by 2 lines.

The Event report is enclosed as Annexure 2J.1.

Committee noted


2J.2 Substation: Satna (PG) Substation / JP Nigrie

Date & time: 12.06.2018 at 19.03 hrs. (134th PCM Agenda item no 2G.1)


(134th PCM Agenda item no 2G.2. JP Nigree representative was not present in the 134th meeting and therefore the disturbance could not be explained to the sub-committee.)


On 12.06.2018 at 19.03 hrsthere was a grid incidence at Satna (PG) s/s.

400 kV JP Nigrie-Satna 2 tripped on R-E fault and at the same time circuit 1 auto reclosed successfully on B-E fault.

Satna STATCOM coupling transformer and JP Nigrie units also tripped on LV side backup protection operation and Reverse power protection operation respectively.

Trippings observed are as follows: o 400 kV JP Nigrie-Satna 2 o 660 MW JP Nigrie Units 1&2 o 400/38.5 kV Satna STATCOM coupling transformer o 150 MVAR Satna STATCOM 1&2


JP Nigrie representative informed the following;

Single Line Diagram







JP Nigree representative informed to the committee that after the incident, time delay was increased from 1 Sec to 1.3 Sec. In relay Settings of Standby E/F Protection for GTs

JP Nigree representative also informed that apart from this, the following remedial measures were also taken.:

Transmission Line : A. ADDITIONAL SINGLE I SUSPENSION PILOT INSULATOR

STRING HAS BEEN PROVIVED. B. ADDITIONAL EARTHING HAS BEEN PROVIVED IN 10 NOS

TOWERS OF HIGH ALTITUDE. C. JUMPER RECTIFICATION / REPLACEMENT WORKS.


2J.3 Substation: Tripping of Units at ACBIL,MCCPL, ACBIL Chakabura and SCPL

Date & time: 03.06.2018 at 16.26 hrs. Event Category: GD-1

(134th PCM Agenda item no 2G.3. ACBIL representative was not present in the 134th PCM meeting and therefore the following disturbance could not be explained to the sub-committee.)


Loss of evacuation lines due to earth faults led to the tripping of Units at ACBIL,MCCPL, ACBIL Chakabura and SCPL.

Trippings observed are as follows: o 400 kV MCCPL- Bilaspur o 400 kV ACBIL - Bilaspur o 400 kV MCCPL- ACBIL o Unit 1&2 ACBIL (135*2 MW) o Unit 1&2 ACBIL Chakabura (30*2 MW) o Unit 1&2 SCPL (50*2 MW) o Unit 1 MCCPL (300 MW)


Committee observed that ACBIL representative was not present in the meeting and therefore the disturbance could not be explained to the sub-committee. The same shall be taken up in the next PCM.

2J.4 Substation: Pirana S/s (TPL )

Date & time: 26.10.2018 at 15.31 hrs Event Category: GI-1


On 26.10.2018 at 15.31 hrs there was a grid incidence at Satna (PG) s/s.

At Pirana S/s, metallic yarn fell on 132 kV bus 1 and resulted in tripping of associated elements on Bus bar protection operation.

Trippings observed are as follows: o 400/132 kV Pirana ICT 1 o 400/132 kV Pirana ICT 3 o 132 kV Pirana Bus 1 and associated elements.

The SLD/Event Report is enclosed at Annexure 2J.4.



TPL representative informed the following;

Bus1 Fault occurred due to Metallic Yarn shorted near PIRANA Line-1 R-Phase CT of BUS-1, Busbar protection relay detected by the below values and released the Trip to Bus1.

Bus-1 Connected feeders Tripped with Bus coupler.

RESULTANT R-PHASE BUSBAR RELAY DIFFERENTIAL VALUES:

Bus Zone-A Value Bus Zone-B Value Tripping

ZA IIN ZA ID ZB IIN ZB ID

7.6603 kA 7.9366 kA 3.5109 kA

7.7837 A CHECKZONE TRIP BUS-1 TRIP

Trip Result: As per the above Fault values Bus-1 and Check Zone Differential current shows the R-Phase Fault. Accordingly, R-Phase Busbar relay released the trip command of Bus-1 with Buscoupler.

Simultaneously, BUS-1 PIRANA F1 R-Phase CT fault extended to PIRANA Line-1 side

(In zone fault of NPR-PR Line differential protection)

Both Substation end, Line differential relay detect fault in R-Phase and differential protection was operated correctly.

RESULTANT BOTH SUBSTATION END LINE DIFFERENTIAL RELAY OPERATED

Bus 1 Fault Detected with Trip Log Information Trip Command for Bus1 L1 @26.10.2018 15:31:37.468.

• Bus1 Connected Bays: PR-F1, PR-F3, VASNA F1, PHD F1, VINZOL F1, 75M TR-1, METRO-F1, ICT-1, ICT-3

• Bus2 Connected Bays: PR-F2, VASNA F2, PHD F2, VINZOL F2, ICT-2, ICT-4

• Bus coupler Status: Closed


BUS-2

NPR-

PHD F

1

ICT-2

ICT-3

ICT-1

BUS-1

BC

NPR-

PR F3

NPR-

PR F1

NPR-

V F1

NPR-

U F1

MET

RO F1

75M

TR-1

NPR-

PR F3

2

NPR-

V F2

NPR-

PHD F

2

400KV BUS-2

400KV BUS-1

26.10.2018 15:31:37.468 BUS-1 BUSBAR PROTECTION OPERATED

ICT-4

PGCIL

F2

PGCIL

F1

SUGE

N-2

UNOS

UGEN

L1-E

400/132KV PIRANA SLD

BCNP

R-U

F2

DIFFERENTIAL RELAY VALUES:

Measuring Signal 132KV NPR SS

Value

132KV PR SS Value

LINE_IL1 25.256 kA 1.4234 kA LINE_IL2 357.82 A 298.16 A LINE_IL3 267.55 A 227.12 A LINE_IN 25.310 kA 1.3928 kA REM_LINE_IL1 1.4055 kA 20.788 kA REM_LINE_IL2 355.64 A 285.91 A REM_LINE_IL3 262.86 A 223.26 A REM_LINE_IN 1.3735 kA L3D-IBIAS 6.2134 kA 4.2349 kA L3D-IDL1MAG 6.8620 kA 4.2472 kA L3D-IDL2MAG 0.6874 A 1.1018 A L3D-IDL3MAG 0.3742 A L3D-IDNSMAG 0.00000 A 0.00000 A



Metallic yarn fell over 132 kV Pirana Bus 1 and resulted in tripping of all the elements connected to 132 kV Bus 1 along with the bus coupler.

As seen from the PMU plot, the fault was R phase fault and got cleared within 120 ms and the Bus bar protection operation was found in order.


2K. Follow up of compliance of 128th PCM to 134th

PCM recommendations

The compliance status of the 128th to 134th PCM recommendations was

placed before the committee.

Utilities were requested to furnish the compliances in the PCM.

Discussion in 134rd PCM:

Committee discussed the compliances of the pending recommendations of past PCMs and the updated status is enclosed at Annexure 2K.1

Discussion in 135th PCM: Committee observed the status of compliances of the recommendations of

past PCMs are yet to be submitted by constituents and all the Utilities

were requested to furnish the compliances at the earliest to PCM.

ITEM NO. 3: Tripping of lines / ICTs :

The minor incidences of tripping of lines and ICTs during the period 01-

10-2018 to 31-12-2018 to be discussed is enclosed at Annexure–3.

Committee noted.


ITEM NO. 4: State Level Relay Co-ordination Groups:

Back ground: In the 128th& 129th PCM the issue of formation of “State level Relay Co-ordination Group” (SRCG) was discussed in detail to review the relay settings within the State, so that the settings are co-ordinated. It was decided that SLDC shall be the convener of the group and the SRCG of the States shall periodically review the relay coordination in their State. The proposals for revision of relay settings then shall be put up to the PCM forum for ratification. 131st& 132nd PCM discussion: Following critical areas were identified for relay protection co-ordination in the 131st PCM;

Maharashtra Akola, Talegoan, APL Tirora and Mumbai-MSETCL interconnections.

Gujarat SSP, Kakrapar,Kawas&Gandhar. MP Omkareshwar&Damoh. Chattisgarh Korba (W) &Bhilai.

132nd PCM updates:

In the 132nd PCM, WRPC informed that in order to expedite the matter, a letter conveying the decision regarding identified critical networks in the States was sent to all SLDCs from WRPC Secretariat.

Gujarat representative informed that the 1st meeting of the relay co-ordination group for the systems of Akrimota and Panandroh S/s were taken up in October 17 and issues observed were rectified. The 2nd meeting of the relay co-ordination group is planned in first half of May 2018.

MP representative stated that 1st meeting has been convened and the system of Omkareshwar was identified. Second meeting is scheduled to be held in May 2018.

Maharashtra SLDC representative stated that the State level group has been formed and the 1st meeting was proposed to be held in April 18. However due to reshuffling of engineers in MSETCL the same has been postponed and protection co-ordination of the interface lines with Mumbai system would be held shortly.

133rd PCM Discussions : Maharashtra representative informed that the first meeting was held on 23rd April 2018 to review the relay coordination of Mumbai Interconnections between MSETCL & TATA. CSPTCL representative informed that the first meeting was held and the MoM would be shared shortly.


Committee stressed that regular meetings of the State level Relay Co-ordination groups be held for review of relay coordination of interconnections and the MoM be shared with PCM.

4A.5.) NPCIL informed that M/s MSETCL vide letter dated 05.05.2018 indicated that the proposed distance relay settings found correct.

Proposed relay settings (at TAPS 1&2 end) for 220kV TAPS-Boisar& TAPS-Borivali feeders distance protection relays were sent to M/s MSETCLfor review.

M/s MSETCL has indicated vide their email dt.05.05.2018 that, the proposed relay settings(at TAPS 1&2 end)for TAPS-Boisar& TAPS-Borivaliare checked & found correct.

The gist of proposed changes in the settings is attached as Annexure-4A.5.

The proposed settings (at TAPS 1&2 end) of TAPS-Boisar& TAPS- Borivali distance relays are enclosed herewith for your concurrence & approval please.

4A.6.) 134th PCM Discussions: As far as Item 4A.5) above Committee suggested that the settings should be mutually agreed between NPCIL, MSETCL & GETCO and the same can be implemented by NPCIL on receiving communication of confirmation from MSETCL & GETCO. 4A.7.) 135th PCM Discussions: Maharashtra representative informed that the second meeting on Relay Setting Coordination Group (RSCG) was held at SLDC,Airoli, Navi Mumbai on 13th August at 11.00 hrs. During the meeting protection setting coordination of 220 KV TAS & MSETCL lines were discussed. MoM of the meeting enclosed as annexure 4A.7 (A).

SLDC, Gujrat representative informed that 2nd level Protection committee was held on 08.05.2018, during the meeting CEA guidlines of Ramakrishna committee ,inspection of AUFLS scheme, review of SPS were discusses. MoM of the meeting enclosed as annexure 4A.7 (B).

Committee stressed that regular meetings of the State level Relay Co-ordination groups be held for review of relay co ordination of interconnections and the MoM to be shared with PCM.

As far as Item 4A.5) above Committee suggested that the settings should be mutually agreed between NPCIL, MSETCL & GETCO and the same can be implemented by NPCIL on receiving communication of confirmation from MSETCL & GETCO.


ITEM NO. 5: Hon’ble CERCs orders on the Grid disturbance of 30.07.2012 & 31.07.2012

5.1: Compliance Status observations made in Protection Audit

(Petition No. 220/MP/2012) Back Ground:

5.1.1) Back ground:

CERC vide its order dated 21.02.2014 in respect to petition No. 220/MP/2012 filed by POWERGRID have directed that CTU and SLDCs shall submit quarterly Protection Audit Report to the respective RPC latest

by15thday of the first month of next quarter and RPCs shall submit the

report to the Commission latest by15thday of the second month of next quarter. The Member Secretary of Regional Power Committees shall monitor the protection related issues and bring to the notice of the Commission any instance of non-compliance of the Regulation1.5of the Grid Code in respect of the protection related issues considered in the instant petition.

5.1.2) 128th& 129th PCM discussion:

New substations have been integrated to the grid at 400 and 765 kV level like Kala, Daman, Vadodara, Nanded, Chandrapur2, Koradi3, Koradi2, Pune, Pune GIS, Kolhapur GIS, Durg, RaigarhTamnar, Kotra, Dharamjaigad, Jabalpur PS, Vindhyachal PS, Vindhyachal stage 4 and 5, Indore PG, Marwa, Raita, Astha, Sujalpur PG. Therefore, utilities may kindly propose the dates for the third party protection audit as per the format given in the Ramakrishna Committee report.

GETCO, PGCIL & NTPC intimated that all the protection audit observations for protection audit carried out in phase-1 have been complied. Further Maharashtra, Chattisgarh and MP intimated that protection audit observations for protection audit carried out in phase-1, not involving procurements have been complied

5.1.3) 131st PCM discussion:

It was informed that the compliances received from the states for the third quarter (October to December 2017) have been sent to CERC, the same is available on WRPC web site www.wrpc.gov.in-->meetings-->Protection-->Minutes-->PAR_Dec_2017_latest.

Maharashtra representative stated that they are taking up the protection audit in a phased manner and they have already identified the S/Ss to be taken up for protection audit. Further the compliances are mainly pending for protection audits carried out in the recent past.

Gujarat & MP representatives stated that they have also taken up identification of the S/Ss for protection audit and the same shall be intimated to PCM as soon as it is done.


5.1.4) 132nd PCM discussion:

The forum requested Gujarat to provide the breakup of 114 nos of Substations where first phase Protection Audit completed the before 2012. The forum also requested PGCIL to submit the status in above format.

Member Secretary, WRPC expressed that the progress on above subject matter is slow. This issue of Protection Audit was also discussed in Grid Study Committee meetings. Since Protection audit activity is a cyclical activity so after every five years protection audit of all the critical S/Ss above 220kV level has to be carried out. Therefore it is utmost necessary to comply with all the Protection Audit observations of the first phase and take up second phase of Protection Audit.

Committee requested all the utilities to get all the Category B protection audit observations attended, take up protection audit of newly commissioned S/Ss and S/Ss where protection audit has been carried out 5 years back.

PGCIL may submit the status in the above format. GETCO may provide the break up details of 114 no’s of Substations where first phase Protection Audit completed the before 2012. A letter has been written from WRPC secretariat to all the constituents asking the update and status and action plan for 2nd phase of protection audit. Constituents/STUs may update the status.

The data has not been received yet Utilities are requested to furnish the data of Protection Audit already carried out and the tentative plan of Protection audit of new and existing S/Ss in their system.

5.1.5) 133rd PCM discussion:

The status regarding the taking up the protection audit of second phase was discussed and the update on the same is as follows; PGCIL, GETCO & MPPTCL representatives informed they have already planned the activity to be done through independent agency. MSETCL representative informed that they are planning to carry out the protection audit through independent agency. NSPCL representative informed that they have already carried out PA of their S/S. NTPC & CSPTCL representative informed that they will inform the status shortly.

5.1.6) 134th PCM discussion:

It was informed that the compliances received from the states for the second quarter (July to September 2018) have been sent to CERC, the same was available on WRPC web site http://www.wrpc.gov.in/pcm/PAR_September_2018.pdf.


135th PCM Discussions:

CERC vide its order dated 21.02.2014 in respect to petition No.

220/MP/2012 filed by POWERGRID have directed that CTU and SLDC s

shall submit quarterly Protection Audit Report to the respective RPC latest

by15th day of the first month of next quarter and RPC s shall submit the

report to the Commission latest by15thday of the second month of next

quarter.

Protection Audit Report for the third quarter of 2018-19 (October to December 2018) has not received from the CTU and SLDCs. Committee requested all the utilities to furnish the protection audit data timely. The updated status (in 135th PCM) of the protection audit observations is as given below

Year State /utility

No of S/s Audited

Obseravations in Category A (Procurement not required)

Obseravations in Category B (Procurement required)

Status FC/PC/

NC

Remarks if any No of

Deficiencies Observed

No of Deficiencies rectified

No of Deficiencies pending

No of Deficiencies Observed

No of Deficiencies rectified

No of Deficiencies pending

2012-13

Gujarat

S/s Audited before 2012 - 121

3781 3781 0 NA FC

Protection Audit completed before 2012 and all are complied

S/s Audited before 2012 - 13 are - 121 1191 1191

0 NA FC

Protection Audit completed before 2012 and all are complied

MP 12 80 79 1 76 38 38 PC

Maharashtra 122 114 114 0 53 53 0 FC

Chhattisgarh 13 15 15 1 61 4 57 PC

PGCIL (WR-I) 11 9 9 0 0 0 0 FC

NTPC 4 8 8 0 5 5 0 FC

IPPs 1 11 11 0 0 0 0 FC

2013-14

Gujarat 11 611 611 0 NA FC

MP 25 83 82 1 42 14 28 PC

Maharashtra 154 147 147 0 92 88 4 PC


PGCIL

IPPs

2014-15

Gujarat NA NA NA NA NA NA NA FC FC

MP 18 94 89 5 55 30 25 PC

Maharashtra 107 210 209 1 93 92 1 PC

Chhattisgarh Nil Nil Nil Nil Nil Nil Nil


PGCIL

IPPs

2015-16


MP 17 79 76 3 35 16 19 PC

Maharashtra 120 251 248 3 225 223 4 PC


PGCIL (WR-I) 6 18 18 0 0 0 0 FC

IPPs

2016-17


MP

Maharashtra 106 204 198 6 6 2 9 PC

Chhattisgarh Nil Nil Nil Nil Nil Nil Nil

PGCIL

IPPs

Committee noted.

5.2: Relay Setting Database : Hon’ble CERCs order on

GridDisturbanceon30.07.2012 &31.07.2012 (PetitionNo. 167/Suo-

Motu/2012)

5.2.1) Background:

Hon‟ble CERC‟s vide order dated 22.02.2014 in the matter of grid

disturbance occurred on 30.07.2012 & 31.07.2012 in petition

No.167/Suo-Motu/2012, have made certain observations and issued

directions.

According to this order, all the RPCs have to maintain the relay settings

data fall the ISTS lines and lines emanating from interface S/S s of Utilities

to ISTS (400kV& above and 220kV interfacing lines).Therefore all utilities

were requested to submit relay setting data to WRPC/WRLDC.

5.2.2) 131st PCM discussion:

PGCIL WR-II, Chattisgarh& Goa was requested to submit the data.

5.2.3) 132nd PCM discussion:

For the generators of the states, the forums requested respective SLDCs

to co-ordinate and send the data.

Further since the issue is long pending, the forum requested utilities to


submit the data as per strict format given by WRPC avoiding merging of

cells in the excel format so that the data importing in the database

becomes easy and give intimation WRPC.

PGCIL have submitted the data.

Committee requested SLDCs to coordinate with the generators in their

system to submit the data to WRPC at the earliest.

Chattisgarh& Goa may update status.


It was informed that most of the data has been received & the activity of

preparing database has been started.


Committee noted.

135th PCM Discussions :

Committee noted.

ITEM NO. 6: Task Force report

Report of the Task Force on Power System Analysis Under

Contingencies:

Background:

Ministry of Power, GoI constituted a “Task Force on Power System

Analysis under Contingencies”, in December 2012 under the

chairmanship of Shri V. Ramakrishna as per the recommendation

made by Enquiry Committee headed by Chairman, CEA on grid

disturbances that took place in NEW grid on 30thand 31stJuly 2012.

The terms of reference of Task Force broadly cover analysis of the network

behavior under normal conditions and contingencies, review of

operational philosophy of protection relays, review of islanding schemes

and technological options to improve the performance of the grid. The

report of the Task Force was discussed briefly in 122nd PCM and

subsequently discussed in detail in a special meeting held on 18.12.2014.


Thereafter the recommendations were discussed in the previous PCMs.

A brief on suggestions given by Ramakrishna Committee,

discussions/observations of the group and PCM are as follows.

6.1) Formulation of Special groups for studies and protection

coordination:

The Task Force recommended forming a group for studies, protection

coordination and relay settings. It also recommended that each utility

should establish a protection application department with adequate man

power & skills. The members of protection team shall undergo regular

training to enhance their skills.

6.2) Tuning of power electronic devices & PSS: The Task Force

recommended carrying out studies & reviewing the network at regular

intervals (3-4 years) with introduction of newer power electronic devices.

The results may be implemented within next 3-4 years. It also suggested

that as this requires specialized dynamic modeling, the task may be

entrusted to reputed independent agency and implementation of tuning

be entrusted to respective manufacturer.

6.3) 128th PCM Discussions: It was decided that the tuning of power

electronic devices & PSS in WR be carried out by availing the

consultancy/training services of IIT-B and a separate meeting be called

to deliberate on the modalities of carrying out the PSS tuning activity in

WR.

Accordingly a meeting was held on 03.01.2017 at WRPC Mumbai, wherein

representatives of all the generating companies, SLDCs and expert from

IIT-B attended the meeting.

1) A software for testing the performance analytically would be developed

by IIT-B after discussing the requirements with WRPC.

2) A simulation software for exciter/PSS control system simulation shall

be developed by IIT-B, which shall be made available to all the generating

companies of WR for checking/simulating the frequency response of the

PSS tuned system.

3) The cost of the software at 4 & 5 be funded through WRPC fund.


WRP Committee in the 33rd WRPC meeting held on 01.02.2017,

agreed and gave approval for funding the studies software as above

from WRPC fund.

6.4) Past PCM updates:

NTPC, Maharashtra Genco and MP Genco representatives informed that the PSS is in-service for all the eligible generators in their system. GSECL representative stated that the PSS tuning activity has been taken up with BHEL. MSPGCL representative stated that they have also initiated the activity of PSS tuning and enquiry has been placed with M/s BHEL. It was decided that all the generating companies to submit the PSS settings and the step test response plot of time vs terminal voltage in Excel sheets to WRLDC & WRPC. 6.5) 131st PCM discussion:

WRPC informed that there is a need to review the nominations of the study group for taking up studies. Fresh nominations from SLDCs, STUs, PGCIL WR-I & WR-II, NTPC and WRLDC be sought and the network updation/building work be under taken after formation of the group.

6.6) 132nd PCM discussion:

A meeting was held between WRPC & IIT-B in Oct.-2017, wherein IIT-B felt that the scope of involvement of BHEL(OEM of the most of the exciter system in WR) needs to be discussed with BHEL. Also they would study the scope of the work once again after consulting with BHEL. He further informed that IIT-B has recently communicated that they would like to discuss the matter again. WRPC would hold a meeting with IIT-B for deciding the further course of action. As regards to formation of regional study group, fresh nominations have been sought from SLDCs, STUs, PGCIL WR-I & II, NTPC & WRLDC vide WRPC letter dated 16.04.2018 (enclosed at Annexure-6.6) However nominations have not been received yet. In order to start the above activity nominations from STUs, SLDCs, CTU, WRLDC, State GENCOs, NTPC and IPPs is required to be given to WRPC at the earliest.

6.7) Follow up actions:

(1) NTPC, IIPs & State GENCOs to update on the step response to PCM forum. (2) SLDCs, STUs, PGCIL WR-I & WR-II, NTPC and WRLDC to give fresh nominations for Specialgroups forstudies andprotection coordination for WR. (3) WRLDC to give a compilation on the step response results in respect of the generators of WR.


6.8) 133rd PCM discussion:

The nominations received for the study group is as follows;

(i) NTPC- Shri D. Roy Chowdhary AGM NTPC. (ii) SLDC Maharashtra- Shri SachinLamte (iii) MSETCL testing- Shri Vekhade (iv) TPC-Shri G. T. Jawale (v) APL-Shri Sandeep (vi) Reliance-Shri Karekar. (vii) WRDC-Smt.PushpaSheshadri. (viii) SLDC MPPTCL-Pradeep Sachan

GETCO, CSPTCL, PGCIL WR-I & II representatives informed that they would confirm their representation for the study group shortly. The PSS tuning status received from WRLDC is enclosed at Annexure-6.

6.9) A workshop on PSS tunning activity in WR was arranged in association with IIT-B on 30.08.2018 at WRPC Mumbai. M/s TATA Power, SASAN UMPP, NTPC representative gave presentations. Shri K. Parthasarthi Electronics Division BHEL and Dr.Anil Kulkarni Professor IIT-B who where associated in the PSS tunning of WR in Phase-I & II also gave presentations on the PSS tunning. Around 50 participants attended the workshop, where queries of the participants were answered by Shri K. Parthasarthi Electronics Division BHEL and Dr.Anil Kulkarni Professor IIT-B.

It was stressed that the association of the OEM of the excitation system of the generator is required to be involved in the PSS tunning activity. It was also advised that now PMUs are being deployed in the system and therefore the data (oscillations) recorded by the PMU (during tripping of nearby lines from the generating station) nearby the generation stations can be utilized to decide upon the parameters required to set for PSS. This data can be shared with the OEM of the excitation system, who will then help out in deciding the PSS parameters for tuning it.

Regarding the modalities of taking up the activity in WR, Dr.Anil Kulkarni Professor IIT-B informed that they are working on how to proceed on the development of the software and they would revert back once it is finalized.

6.9) 134th PCM Discussions:

Due to paucity of time the item could not be discussed, therefore the same would be taken up in the next PCM. 6.10) 135th PCM Discussions:

The 1st meeting of the WR Study Group was held on 29.10.2018 at WRPC, wherein it was stressed that the updated network upto 31.09.2018 and the planned network and system data upto March-2019 be submitted to WRPC for taking up the Capacitor Studies. Committee requested to submit the updated network upto 31.09.2018 and the planned network and system data upto March-2019 to WRPC for taking up the Capacitor Studies.


ITEM NO 7: SPS

7A) SPS for 765kV Agra-Gwalior for load shedding in NR and

automatic generation backing down in WR:

7A.1) Back ground:

7A.1.1) In the 129th PCM, PCM suggested that the SPS conditions at both Agra and Gwalior end be sensed independently and if SPS conditions at either end are satisfied their shall be independent signal generation and a decision based on the signals generated at both ends should be transmitted to the generators of WR and loads in NR, as the case may be, so that there is adequate redundancy in the SPS. Further as regards to testing the SPS, secondary injection method should be done while carrying out the mock testing of SPS, so that whole SPS except CTs is tested.

7A.1.2) In the 130th PCM, PGCIL representative stated that at present it would be difficult to extend the SPS signal from both Agra and Gwalior ends to all the generators in WR and loads in NR individually. However the exchange of SPS signal generated on meeting of the SPS condition can be exchanged and sent to generators in WR and loads in NR. Further PGCIL confirmed that the exchange would be carried out on Fiber communication.

7A.1.3) Subsequently, NRPC vide letter dated 18.05.2018 (copy attached as Annexure 7A) informed that issue of revised SPS scheme was taken up in their OCC meeting and is being implemented at Agra end. NRPC have further informed that they have included the breaker status in the SPS sensing for loss of import of 1000MW & 1500MW at Agra end. PGCIL NR have informed NRPC that they agreed for including breaker status monitoring in the SPS. WRPC have been requested for expediting the inclusion of breaker status in the SPS at Gwalior end also. 7A.1.4) 133rd PCM discussion:

PGCIL representative informed that there are some issues in continuous monitoring of the remote end breaker status at both ends. It was suggested that instead of continuous monitoring of the breaker status, a signal of tripping of the breaker status can be sent to the remote end which would be incorporated in the SPS logic. It was decided that both the line breaker status of tripping be sent to remote end and this would be an additional condition for generating the SPS signal, when the loss of import in NR is more than 1000MW to 1500MW, for backing down (in WR) from Gwalior end and Agra end respectively. 134th PCM Discussions: Due to paucity of time the item could not be discussed, therefore the same would be taken up in the next PCM. 134th PCM Discussions: PGCIL representative informed that a signal of tripping of the breaker status has been incorporated in the SPS logic during the month of January 2019.


ITEM NO. 8 : WRLDC Items from 129th PCM for

followup :

8.1 Mock Testing of Local and Wide area System Protection Schemes (SPS) in Western Region 8.1.1) Background : The details of local SPS are as follows :-

1. CGPL SPS 2. Sasan SPS 3. JPL Stage 1 & 2 SPS 4. Essar Mahan SPS 5. Sipat SPS 6. APL Mundra SPS 7. APL Tiroda SPS 8. High Frequency SPS (tripping of Korba Unit 7,

Vindhyachal Unit 7, CGPL Unit 40)

Details of Inter-regional SPS Schemes (Wide Area) are as follows:

1. Agra-Gwalior SPS at Gwalior end. 2. HVDC Mundra Mohindergarh SPS

In the 129th PCM it was decided that mock testing of the local SPS can be done without much coordination and therefore WRLDC may prepare a schedule for mock testing of local SPS and carry out the mock testing as per the schedule in coordination with the generators concerned. The Wide Area SPS requires coordination among the inter region, therefore these shall be scheduled in consultation with the NLDC and respective RLDCs. In the 130th PCM it was decided that wherever the SPS has operated successfully in the recent past, it would not be required to carry out the mock testing of SPS. In the 132nd PCM, WRLDC representative informed that the Mouda SPS was removed as intimated by NTPC.


No reply was received from NTPC regarding deactivation of Mouda SPS.

8.1.3) 134th PCM discussion:

The updated status of recent successful operation of SPS received from

WRLDC is enclosed at Annexure-8.1.3.

8.1.4) 135th PCM Discussions:

Committee recommended that WRLDC will prepare a schedule for mock testing of local SPS in consultation with the concern entity. With regard to mock testing of wide area SPS schemes, WRLDC shall prepare the schedule in consultation with NLDC and concern entity. All entity shall furnish their proposed schedule of mock testing of local SPS to WRLDC with intimation to WRPC at the earliest.


ITEM NO.9: Notifying violation of CEA Protection (Grid) Standard in case of tripping of inter-regional lines of voltage class 220 kV and above level of WR:

CEA vide letter dated 30.08.2017, have intimated that following protection standards were reportedly violated in respect of following cases; a) Non-availability of A/R at both ends of 220kV lines b) Non-submission of DR/EL data to RLDC within 24 hours of the event. c) Non-intimation of main reason for the events after its complete analysis. d) Higher fault clearance time than prescribed in the standards. CEA has further directed that if the non-compliance of Grid/Standards/ Grid Code continues, the matter may be reported to CERC under provisions of the Grid Code, with a copy of the report to CEA. In the 130th& 131st PCM, the sub-Committee requested all the utilities concerned to report the compliance to WRLDC/NLDC with a copy to WRPC. 133rd PCM discussion: Committee requested all the utilities of WR to checkup the violations as has been brought out by NPC, CEA and report the compliances at the earliest. 134th PCM discussion: Committee requested all the constituents to submit the action taken report on the above. WRLDC vide letter dated 11.01.2019 (copy enclosed as Annexure 9.2) reported the list of 220 kV and above line trippings in which the CEA Protection standard Violations were observed for the months of Nov & December 2018. In which the details of Protection Violation such as Delayed Auto reclose operation, Non-operation of Auto reclose and Delayed fault clearance have complied with the help of Voltage plots from PMUs. 135th PCM discussions: Committee requested all the utilities of WR to strictly follow the CEA’s protection standard in future in order to ensure safe grid operation.


ITEM NO. 10: Review of Mumbai Islanding Scheme:

10.1) Background: Tata Power Mumbai vide letter dated 23.10.2017 requested to review the existing Islanding Scheme. 10.2) 131st PCM discussion: The sub-Committee discussed the above and felt that there is requirement of shedding additional load of around 400MW so as to match the load with the generation in case the Island separates from the rest of the grid. It was decided to hold a separate meeting on 13.03.2018 by involving TATA, BEST, Reliance-DISCOM, Reliance TRANSCO, MSETCL, WRLDC& WRPC.

10.3) Special Meeting held on 13.03.2018:

Accordingly a meeting was held on 13.03.18 at WRPC Mumbai and the decision taken in the meeting is as follows; It was decided that if additional 300 MW load is shed then the island can be saved in case of Grid Disturbance. This additional 300 MW load to be shed, be shared proportionately among TPC and BEST on pro-rata basis peak demands (TPC would share 107 MW and BEST would share 193 MW). It was further requested that these load shedding be implemented as soon as possible. Representatives from TPC and BEST told that wherever Procurement is not required, it will be implemented within a month and wherever procurement will be required, it will take 3-4 months of time.

10.3) 132nd PCM discussion:

TPC representative informed that for existing substations where relays are available, it will be implemented by April 2018 end and where procurement is required, additional 6-8 months of time will be required. MS WRPC requested TPC & BEST representatives to take up the issue of procurement of UFRs with their management and implement (wire up) the above additional load for shedding as early as possible. Subsequently, WRPC vide letter dated 12.06.2018 (Copy enclosed as Annexure 11.3) requested TATA Power and BEST to give update at the earliest.

TPC/BEST may update on the above.

133rd PCM discussion: TATA Power representative informed that out of their share of 107MW 90MW has been wired up with the existing UFRs and remaining 17MW would be wired up with the existing UFRs by July 2018 end, as an interim measure. He further informed that meeting with BEST representative was held in 1st week of July 2018, wherein it was decided that 150 MW out of 193MW(total BEST share) would be wired up by August 2018 end. As regards to procurement of additional UFRs the process has been initiated.


A meeting on the Mumbai Islanding scheme was held at CEA New Delhi which was chaired by Chairperson CEA on 10.10.2018. In this meeting all the utilities(Mumbai) were requested to submit the prioritization of the critical loads in their system. The same was submitted to CEA.

134th PCM discussion:

TPC representative informed that the load shedding quantum of 200MW has been wired up through existing UFRs.

10.4) Meeting at CEA :

A special meeting to discuss the constraint scenario in Mumbai Transmission System scheme was held on 10.10.2018 at CEA New Delhi, wherein inadequacy in the existing islanding scheme with the increasing imports was discussed. In the meeting it was suggested that it is essential to review the loads included in the category of critical ones and prioritize them for serving in the island with loads pertaining to general public safety giving high priority. It was decided that all the Mumbai DISCOMs would resubmit the details of critical loads along with explanations/ descriptions thereof and their priority for retention in the Island. Each DISCOMs would also broadly categorize the critical load into two groups i.e. shed able load and non-shed able load during Island formation. The above data was obtained from the DISCOMs in Mumbai(TATA,BEAT & Adani ) and was forwarded to CEA New Delhi. The data forwarded is enclosed at Annexure-10.4.


Committee noted as above .

ITEM NO.111Certificate for Healthiness of Batteries

11.1.1) Background:

As per the MoP direction given in pursuant to recommendations of the Enquiry Committee (NEW grid disturbance on 30th & 31st July, 2012), RPCs are required to obtain from their respective Constituents the monthly certificate for healthiness of batteries, installed at 220 KV and above voltage level Substations (for power supply to Relays, RTUs and PLCC equipment) and furnish the same to CEA/MoP. With reference to above, the Constituents are requested to submit the certificate on healthiness of batteries on monthly basis (i.e. status for a month shall be sent by the 7th day of the following month) to WRPC Secretariat.

A format for certificate for healthiness of batteries have sent to the members through email dated 20.04.2018.


133rd PCM discussion:

The certificates have been received from KSK Mahanadi, TRN Energy, GSECL/GETCO, MSETCL, TATA Power, Essar Power, Rinfra, NCA, SKS, CGPL, PGCIL WR#2, LANCO, Jaypee Nigrie, NSPCL, GSEL, MCCPL.


Committee requested constituents to give regular certification of the healthiness of the station batteries.


The certificates related to healthiness of the station batteries have been received from some of the entities such as KSK Mahanadi, TRN Energy, GSECL/GETCO, MSETCL, TATA Power, Essar Power, Rinfra, NCA, SKS, CGPL, PGCIL WR#2, LANCO, Jaypee Nigrie, NSPCL, GSEL, MCCPL. Committee requested other entities to furnish the certificate immedietaly and keep sending regularly.

Committee noted as above.

ITEM NO. 12: Disturbance occurred at 765/400kV Kotra Pooling Station on 23/04/2018.

A meeting to discuss and analyze the disturbance occurred at 765/400 kV Kotra PS on 23/04/2018 was held on 09.05.2018 at WRPC Mumbai. In order to prevent the recurrence of such tripping, the following remedial measures for maintenance activities are recommended for 765/400 kV Kotra substation (of PGCIL) as discussed in the meeting:

(1) As a safety measure, it must be ensured that isolators of

adjoining/bordering live areas (which are not part of the dead circuit area) are opened & locked, and the keys of such Isolator marshalling boxes (MB) are deposited with the Control Room (CR) (i.e. permit issuing authority) before commencing the maintenance activities.

(2) Members suggested that it would be a better safety practice to de-energize the auxiliary supply (i.e. remove the fuse and deposit it with permit issuing authority) of the EHV isolation equipment of the adjoining/bordering live areas.

(3) It must be ensured that only well trained and experienced Engineer/Technician/Supervisor/wiremen are allowed for carrying out the EHV maintenance / testing related works.

(4) The safety procedures and guidelines incorporated in Powergrid ‘Safety Rule Handbook’ and ‘Powergrid Safety Instruction documents’ should be followed strictly for isolation of dead area (i.e. area with permit to work system for maintenance) from adjoining live areas and other safety aspects for maintenance of EHV substation.


(5) It would be a better practice to incorporate the de-energization of the auxiliary supply of the equipments under maintenance and also for adjoining isolating devices which are separating/bordering the maintenance work area.

(6) Proper training to the officials, responsible for maintenance/ testing activities, must be imparted in accordance with Regulation 7 of CEA (Measures relating to Safety and Electric Supply) Regulations), 2010.

(7) Permit-To-Work (PTW) system as given in IS 5216 (Part-I): “Recommendations on Safety Procedures and Practices in Electrical Work” is to be followed for maintenance activities especially for interlocking and safety procedures.

(8) Two simultaneous activities interfering with one another should not be carried out in a single area which is under maintenance.


Member Secretary WRPC informed that PGCIL and all other utilities of WR should follow the suggestions and recommendations brought out as above, so that recurrences of such disturbances should be avoided. WRPC Secretariat informed that in addition to above there are some issues in the protection philosophy and relay settings adopted at Kotra S/S. These issues are as given below;

Protection issues:

(i) At 765 kV Kotra S/S, there is a one and half breaker scheme on 400kV side with 3 CTs. T-section protection is not provided at Kotra S/S. The selectivity as is the practice in PGCIL (as informed by them vide email dtd. 14.05.2018 ) for 3CT scheme is provided as follows;

(a) looking from the Line/ICT (as the case may be) side, the Bus Section beyond Main bay CB is protected by BB protection &

(b) T section between Main Bay and Tie bay CT is protected by line protection or transformer protection( as the case may be). In this approach there remains a blind zone in case Line side or Bus side Isolator is open. Therefore PGCIL may review this and if possible and providing overlapping protection for T-section be explored where ever 3CT scheme is deployed.

(ii) PGCIL vide email dated 15.05.2018 have informed that protection settings adopted in PGCIL is as per the recommendations in “Rama Krishna Task Force Sub-Committee for Power System Analysis”. There is no mention about end zone protection as per the recommendations and therefore the same is not implemented in PGCIL Kotra S/S. The BB protection is of M/s GE(previously ALSTOM) make MICOM P741 type.

Though there is no mention about the End Zone (Dead Zone ) protection in the Task Force Sub-Committee for Power System Analysis report, it is a good practice to have this protection enabled


and isolate the fault through this protection and avoid multiple line trippings and clearance of faults from remote ends. PGCIL should incorporate this protection in the BB protection, since the MICOM P 741 has this feature and all the modern Numerical BB protection scheme have this feature. This would have isolated the fault well before the Zone 2 timings and wide spread of the disturbance would have been avoided. PGCIL may look into it.

(iii) The 765/400kV ICT-I, III & IV backup protection timings at 765kV Kotra S/S needs to be co-ordinated with the Zone-3 timings of the 765kV lines at remote ends. The ICT-I should have tripped from 765kV side backup protection after isolation of the fault from 400kV sides ahead of the Zone -3 timings of the 765kV lines at remote end. PGCIL to review the relay setting coordination.

(iv) There are many 400kV short lines emanating from 765kV Kotra S/S. These are 400kV DB Power D/C-27ms, 400kV Raigarh D/C-6.4kms, 400kV NTPC Lara D/C-19kms, 400kV RKM D/C-20kms, 400kV SKS D/C-27kms. Also, there are long D/C lines followed by short lines. These lines are 400kV Raigarh-Raipur 4 ckts -220kms, 400kV NTPC Lara-Champa D/C-113kms, where it is found that the relay coordination of Zone -2 and Zone-3 is a big issue. Therefore, Line differential relay is required to be provided for these lines to have proper selectivity of the protection.


Due to paucity of time the item could not be discussed, therefore the same would be taken up in the next PCM.


Committee observed that though there is no mention about the End

Zone (Dead Zone) protection in the Task Force Sub-Committee for

Power System Analysis report, it is a good practice to have this

protection enabled and isolate the fault through this protection and

avoid multiple line trippings and clearance of faults from remote

ends.

Committee noted as above


ITEM NO. 13: Details of Protection Audit and

Implemented Defence Mechanism -Reg.

National Power Committee Division (NPC) / CEA vide letter dated 10.09.2018 informed that a meeting was taken by Hon’ble MoSP (IC) on 20.08.2018 to discuss the draft National Electricity Plan. During the discussions CEA has been asked to prepare report and presentations covering aspects of grid reliability and security,especially with respect to grid failure and remedial measures including mechanisms such as is-landing schemes,SPS,UFR,Third Part Protection Audit etc. NPC/CEA vide letter dated 10.09.2018 requested WRPC, the details in prescribed formats on the following may please be furnished

i. Protection Audit Carried out so far and its observations (Annexure -I (a) and I (b)).

ii. Islanding scheme implemented in the region (Annexure -II). iii. SPS implemented in the region (Annexure -III). iv. Status of implementation of AUFLS in the region (Annexure -IV). v. Status of implementation of df/dt relays & its settings in the

region (Annexure -V). WRPC vide mail dated 12.10.2018 and dated 26.10.2018 requested MSETCL,MPPTCL,CSPTCL,GETCO,Goa Electricity Department (GED), DD, PGCIL , NTPC and DNH to furnish the information sought by NPC vide letter dated 10.09.2018 to WRPC at the earliest. However, information was not received from constituents except WRLDC and MSETCL. The letter & formats received from NPC,CEA is enclosed at Annexure 13. 135th PCM Discussions:

SE (P), WRPC informed that the details sought by NPC have been received from WRLDC and MSETCL. He requested MPPTCL, CSPTCL,GETCO,GED,DD,DNH & NTPC to furnish the details in format given at Annexure 13 immediately. PGCIL representative informed that they have furnished the data by mail on 25.02.2019.



ITEM NO. 14: Compliance of Commission’s order dated 26th March 2018 in Petition No.09/SM/2015.

Honorable CERC letter issued under file No.ADMN-11017/14/2018-CERC dated. 26.11.2018 (Annexure 14) wherein Honorable CERC requested to ensure the Compliance of Commission’s order dated 26th March 2018 in Petition No.09/SM/2015 at para 97 had given the following directions.

“ l. CTU to deliberate along with CEA on the issue of MILP based transmission planning or any other formal optimization methodology to be used for network planning along with POSOCO, STUs and other stakeholders at RPCs and CTU to file the conclusions at RPC providing suggestion on optimization tool for network planning to used in the Indian context within 6 months of date of issue of this order.

r. The reliability percentage of a SPS Scheme to be considered while calculating TTC shall be discussed at RPC forum. Effective measures should be taken to expedite ISTS and associated intra-State Order in Petition No. 009/SM/2015 Page 59 of 59 Transmission System to reduce dependency on SPS for safe and reliable system operation.

s. RPCs should ensure the reassessment and implementation of identified islanding schemes after deliberation with stakeholders on the recommendations of the consultant. RPCs to identify additional islanding schemes, as required, periodically.

t. RPCs are directed to ensure that periodic audit of relays/protection system is being carried out and file 6 monthly exception reports to Commission. RPCs are directed to bring out a protocol for checking the relay setting, ensuring healthiness of existing protection system and periodicity of carrying out this exercise and file compliance report in this regard within 3 months of issue of this order. RPCs to take up the issue of protection audit and relay setting in transmission system/distribution system within States. The issue should also be raised at Forum of Regulators so that necessary action may be taken at their level also. RPCs should re-assess the existing SPS in consultation with stakeholders at RPC Forum.”

As regards to “l” above CTU vide letter dated 23.01.2019(copy enclosed at Annexure-14.1), have informed that the matter has been taken up with CEA for convening a meeting to deliberate upon the issue.

135th PCM Discussions: SE (P), WRPC requested all the constituents (GETCO/ MSETCL/ MPPTCL/ CSPTCL/ POWERGRID/ NTPC/ State Gencos and IPPs) to furnish the updated status on the periodic protection audit of their system regularly to WRPC.



ITEM NO. 15: Islanding scheme for Kakrapar Atomic Power Project (KAPP - 3&4) 2x700 MW capacity Nuclear Power Units of NPCIL. NPCIL letter no. NPCIL/Trans/2018/M/29 dated 10.10.2018 (copy enclosed as annexure 15.1) have requested WRPC for evolving an Islanding scheme for KAPS 3 & 4 so that it can be implemented before the unit start up. WRPC vide letter dated 07.12.2018 (copy enclosed as annexure 15.2) requested GETCO, NPCIL, WRLDC to furnish the required information for doing detailed study to evolve the islanding scheme for KAPS 3 & 4. The data required as follows:

1) Data/details/information to be furnished by NPCIL/KAPS:

a) Generation details i. Generation trip details. ii. Speed control operation of governor. iii. UF/LF trip settings. iv. Other relevant requirements.

b) Load details- load to be included in Island.

2) Data/details/information to be furnished by GETCO:

The downstream network & feeder wise loads at the next bus and further downstream low voltage network.

3) Data/details/information to be furnished by WRLDC:

Latest network & peak &off-peakloadings of lines emanating from KAPS & adjacent buses.

A meeting was held at KAPS NPCIL on 14.11.2018 to discuss the Islanding scheme. Generator data was received from KAPS NPCIL vide their letter dated 04.01.2019(copy enclosed at Annexure-15.3). Data be received from GETCO by mail enclosed at Annexure-15.4.


SE (P), WRPC suggested that a separate meeting would be better to discuss and formulate the Islanding scheme for Kakrapar Atomic Power Project (KAPP - 3&4) 2x700 MW capacity Nuclear Power Units of NPCIL and the date of the meeting could be decided and intimated to NPCIL,GECTO& WRLDC later on .



ITEM NO. 16:Formation of Third-Party Protection Audit Teams (TPPAT) for carrying out third party protection audit in WR.

The issue of "Formation of Third-Party Protection Audit Teams(TPPAT) for carrying out third party protection audit in WR" was discussed in the 37th WRPC meeting held on 18.12.2018 and it was agreed to form protection audit teams in WR for carrying out the protection audit of S/Ss in WR.

Table –A: Number of members to be nominated with relay testing and

coordination background.

Utility No. of members to be nominated with relay testing & coordination background

Nomination status

Genco Transco Others

Maharashtra 1 1 - TRANSCO 1. Mr- R. H. Satpute Superintending Engineer Design and Protection Dept. GENCO 1. Mr R S Alone EE(Testing)

Madhya Pradesh 1 1 -

Gujarat 1 1 -

Chhattisgarh 1 1 -

PGCIL: W-1 - 3 - 1. ShSachinSavke, Asst. Manager – Jabalpur PS 2. Sh. Pramod Pathak, Asst. Manager – Rajgarh 3. Sh. Kumar Siddhant, Asst. Manager – Rajgarh

PGCIL:WR – II - 3 - 1. Shri Dinesh Reddy, Dy Manager 2. Shri S Naveen, Asst Manager

NTPC 3 - - Shri Debasish Ghosh, AGM EMD

IPP : APL 1 - -

IPP : CGPL/TATA 1 - -

IPP: SASAN 1 - -

SSP/NCA 1 - -

WRLDC - - 2


Table-B :Number of teams, its composition and duties.

Sl No.

Team Composition System to be audited

1 Team -I 1. Gujarat Transco -1 2. Gujarat Genco – 1 3. PGCIL – 1 4. NTPC -1 5. DNH-1

Maharashtra IIP S/Ss

2 Team – II 1. MP Transco – 1 2. MP Genco -1 3. PGCIL – 2 4. NTPC -2 5. APL

Gujarat Chhattisgarh

3 Team – III 1. Maharashtra Transco -1

2. Maharashtra Genco -2 3. PGCIL 2 4. NTPC-3 5. SASAN 6. Goa

Madhya Pradesh PGCIL

4 Team – IV 1. Chhattisgarh Transco – 1

2. Chhattisgarh Genco – 2 3. CGPL/TATA 4. DD -1 5. SSP – 1 & NPCIL - 1

Goa DD DNH NHPC NPCIL NTPC

WRPC vide mail dated 08.01.2019 requested all constituents to give the nomination so that the work of protection audit can be initiated latest by 15.01.2019. Nominations have been received from PGCIL WR-II & NTPC only. The other constituents in Table-A may give the nominations at the earliest.

135th PCM Discussions: During the meeting it was decided, the details of protection audit teams in WR for carrying out the protection audit of S/Ss in WR to be circulated to the constituents by mail and the constituents has to send their nominations to WRPC before the next PCM.


ITEM NO. 17: Status of implementation of Enquiry Committee recommendations

NPC, CEA vide letter no 7/GSC/NPC/CEA/2019/87-93 dated 16.01.2019 (annexure -17.1) requested to submit the updated status of implementation of Enquiry Committee recommendations. The last updated information of all constituents is enclosed as annexure -17.2. All the constituents are requested to update information and submit the updated information (in excel format enclosed as annexure 17.3) to WRPC, so that the same can be furnished to NPC, CEA. WRPC, vide mail dated 25.01.2019 ([email protected]) requested the constituents to submit the updated status of implementation of Enquiry Committee recommendations at the earliest to WRPC. 135th PCM Discussions: All the constituents are requested to submit the updated status of implementation of Enquiry Committee recommendations at the earliest to WRPC.


ITEM NO. 18: Other issues

18.1 AR relay issue of tie-bay of Ranchodpura#1 (GETCO) feeder at Dehgam

PGCIL WR-II vide letter dated 22.11.2017, requested to discuss the status of rectification of AR relay of tie-bay of Ranchodpura#1 (GETCO) feeder at Dehgam. AR relay of tie-bay of Ranchodpura#1 (GETCO) feeder at Dehgam is faulty since quite long. 131st PCM discussion: GETCO representative stated that the faulty Siemens make A/R is out and the matter has been taken up with Siemens. By March 18 end Siemens would submit their views. 132nd PCM discussion: GETCO representative stated that Siemens have informed them that the A/R is beyond repairs and they are planning to procure new A/R. However retrofitting of panel is required for installation of the new relay. It was informed that the Siemens make 7VK type relays are available and can be procured to avoid retrofitting the panel. 133rd PCM discussion: GETCO representative informed that they have planned replacement of the A/R function through external A/R B-127 spare function. Last week they have sought outage for replacement. However the outage was not given. Committee suggested that GECTO may carry out the replacement work during the next opportunistic outage.


134th PCM Discussions: Due to paucity of time the item could not be discussed. therefore, the same would be taken up in the next PCM. 135th PCM Discussions: Committee suggested that GECTO may carry out the replacement work during the next opportunistic outage.

18.2) Settings of 132 KV Morwa and Waidhan feeders from NTPC TPS Vindhyachal.

18.2.1) : Background

MPPTCL have informed that there are two nos. 132 KV feeders radiating from Vindhyachal TPS viz. Morwa and Waidan. The above lines trips on transient faults of other feeders connected with 132 KV S/S Morwa and Waidhan. It has been informed that at Vindhyachal TPS Zone –I line setting of above lines covers 50 % of next section.

It is, therefore, requested to instruct Vindhyachal TPS to review above setting of Zone-1 to avoid unnecessary tripping / interruption at 132 KV S/S Morwa and Waidhan.


NTPC representative informed that they would require directions from PCM forum in this matter.

Committee opined that there are standard guidelines for line protection and NTPC should implement the standard guidelines for line distance protection for the above lines immediately.

134th PCM Discussions: Due to paucity of time the item could not be discussed, therefore the same would be taken up in the next PCM.


NTPC representative informed that they will coordinate with the management of MPPTCL and resolve the issue at the earliest.



ITEM NO. 19:Recommended methodology for relay settings of uncompensated transmission lines as per Ramakrishna Committee recommendations: - During the 135th PCM meeting PGCIL,WR-II representative requested the sub committeeto include the subject “Installation of back up impedance relay”matter for discussion among all constituents of sub committee and the details of the susubject matter are as follows:

”As per Ramakrishna Committee recommendation on Power Ssytem analysis under contingencies, Zone 3 reach setting of the Transmission line is to be set so as to cover longest line at next bus with a margin of 20 %. However, in such case where Zone-3 reach is set to enter into next lower voltage level, Zone-3 timing shall be coordinated with the back-up protection (Directional over current and earth fault relay) of power transformer. Where such coordination cannot be realized, it is recommended to carry out simulation studies for relay reach & time coordination and suitable solution may be devised. Some of the typical solution can be like application of back up distance protection for power transformer, duplicated protection for downstream 220kV feeders or special protection scheme logic. C opy of the relevant pages is attached as annexure 19.”

135th PCM Discussions: MSETCL representative opined that application of back up distance protection for power transformer as in the above case may help in isolation of the fault ahead of the Zone -3 timings of the lines at remote endduring certain type of faults. PGCIL representative informed that installation of back up impedance relay has been taken up by POWERGRID,WR-I. Wherein, the first stage, both over current and back up impedance will remain in service and after some time (stabilization of back up impedance relays), over current relays will be taken out of service.

Committee noted.

ITEM NO. 20: Date and venue of the next meeting

It was decided that the next PCM (136th PCM) would be held in last

week of March 2019.

Minutes of the 135th Protection Committee Meeting (PCM) of ...

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