Power System Event Analysis

7/24/2019 Power System Event Analysis

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Event Analysis

Calpine CorporationDennis Tierney

April 2015



Fault types

1. Medium Voltage Switchgear

Three Phase Fault.

2. Generator Differential.

2



3

Largest operator of combustion turbines for power generation in the US

Comustion

Turines !1"#$

Steam

Turines !%&$

Other Units (23) Geysers (21)

CCGT fleet (5)

GE !FA ("1)GE #$%&&&

(21)

GEOther

(11)

'ieens 5&1F (3) 'ieens *"(15)

'ieensOther

(11)

3



Typi+al One,#ine for 2-1 .o/er .lant

'



Typi+al One,#ine for 2-1 .o/er .lant

#



Fault types

1. Medium Voltage Switchgear

Three Phase Fault.

"



Fault on $e0iu *oltae us

• '1"&V rea(er was closed to energi)e CT Starting

Motor. *++ro,imatel- two seconds later the

motor deelo+ed an internal three/+hase fault.

• The eent re+ort shows that the rea(er clearedthe fault in aout 3.0# c-cles. The total fault

duration was around fie c-cles.

• *++ro,imatel- 1& c-cles after the fault clearedmost motors connected to the '1"&V dro++ed off

line resulting in the loss of generation.

0



'tartin $otor Event File

%



CC .up Event File



Conta+tor 1&1

To anal-)e this eent -ou

must first understand hownon/latching contactors

o+erate.

1&



Typi+al $e0iu *oltae 4on,#at+hin Conta+tor '+hee

11



Closin the Conta+tor

12

*C +ulses close to

+ic(u+ M rela-. M

contact seals in.



Openin the Conta+tor

13

*T or 0&1 4+ens to

dro+out M rela-.



$- (.ilot) elay

1'

So what powers the control circuit?



$- (.ilot) elay

1#

The 4160V bus.



$anufa+tures Conta+tor Data

1"



O.E464G DE#A7

• Most contactors cannot interrupt fault currents.

• Therefore most contactors’ main contacts have an

!penin" #ela$%

• The !penin" #ela$% allows time for the fuse clear thefault prior to the openin" of the main contactor.

• This &ela$ is present for all trips'opens.

• Varies from manufacture to manufacture

• Some are fi(e&. Some are settable.

10



$anufa+tures Conta+tor Data

1%



hy the Conta+tors Opene0

#ropout volta"e of the M) rela$ *1+0V,- -oil is

aroun& /+V *60. #urin" the fault the bus volta"e

&roppe& to below 4V secon&ar$ an& the M) rela$

&roppe& out.

So2 even thou"h it loo3e& li3e the motors ro&e

throu"h the fault2 the$ &i&n’t. The contactors ha&

actuall$ trippe&'&roppe& out &urin" fault. The maincontacts ust opene& after the fault ha& cleare&.

1



Conta+tor *oltae 'a Dropout Fi8es9

1. 5eplace M) sealin contact with a M contact.

,s lon" as the volta"e recovers prior to the

main contact openin" the M) rela$ will pic3up

a"ain an& 3eep the contactor close&.

2&



Conta+tor *oltae 'a Dropout Fi8es9

+. f $ou cannot a&ust the open &ela$ times2 $ou

can replace the non7latchin" contactor with a

latchin" contactor on critical motors.

• -ostl$• +/ trip• #- power

• -ostl$

21



Generator Differential

8!9 :;T <S :!!= ,T S!M;

>;8;5,T!5 #;5;8T,: ;V;8TS

9@,T S 5;,: ,8# 9@,T S 8!T

22



Typi+al Generator One #ine

23



eal Generator ,C,G4D Differential Event

2'




2#

5 *6D C P7*S8

V49T*G8S D:4P

!;<8 C4668CT8D VTs$




2"

68=T:*9

V49T*G8 :*>S8S




20

* P7*S8

V49T*G8 :*>S8S




2%

T8:M>6*9 S>D8 5 *6D C C=::86TS1%& D8G. 4=T 4F P7*S8

68=T:*9 S>D8 5 *6D C C=::86TS

1%& D8G. 4=T 4F P7*S8




2

T8:M>6*9 S>D8 *6D 68=T:*9 S>D8C=::86TS 1%& D8G. 4=T 4F

P7*S8?




3&

D8P86DS 46 :89*< M*6=F*CT=:8*S T4 74; T78 :89*< >S

C4668CT8D.




31

T8:M>6*9 C=::86TS D>S*PP8*:;786 5:8*@8:S 4P86

68=T:*9 C=::86TS C46T>6=8

;786 5:8*@8:S 4P86



D6FFEE4T6A# FAU#T'

S T@; 8;)T #;55;8T,: 5;,:?

32



6' T:6' FAU#T EA#9

33



6' T:6' FAU#T EA#9

3'

64 A=MP >6 68=T:*9 V49T*G8

;>99 64T S88 G:4=6D F*=9T >6

V49T*G8S T7*T *:8 C4668CT8D4P86 D89T*.



6' T:6' FAU#T EA#9

3#



C .:A'E CUE4T 'CO.E T6GGEED 7 T6. OUT.UT

3"



T:6' 6' 4OT A EA# FAU#T;

• 5ela$ ha& trippe& before. -Ts chec3e& !=.• 5unnin" on re&un&ant rela$. Trips lifte&.• Monitore& - phase current with scope. 8o

chan"e shown on scope when rela$

operate&.• -urrent chan"e onl$ effects one si&e of

"enerator.• -urrent amplitu&e is too hi"h for a real line

to "roun& fault. :imite& to A710 ampsprimar$.

• Broblem with ,'# circuitr$ in rela$.

30



D6FFEE4T6A# FAU#T'

S T@; 8;)T #;55;8T,: 5;,:?

3%



C .:A'E CUE4T D6FFEE4T6A# T6.

3



T:6' 6' 4OT A EA# FAU#T;

• -urrent chan"e onl$ effects one si&e of"enerator.

• #rop in current.• -hec3e& all connections in -T secon&ar$

circuit.• aile& - phase -T secon&ar$ in rela$.

'&



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