Development of Digital Substation - Challenges ...

July 26, 2019

Development of Digital Substation - Challenges &

Expectations in Utility Context

CBIP – New Delhi

25 th - 26 th July, 2019

Presented by

N. M. SHETH, Executive Engineer

GUJARAT ENERGY TRANSMISSION CORPORATION LTD.

7 th Conference on Advances & Innovations in Substations

In Digital substation,

Primary equipments (Switchgears & instrument transformers) are made intelligent.

Use of Interfacing devices {Intelligent Control Unit (ICU) & Merging Unit (MU)}

Substation functionality : Achieved through software, with lesser reliance on

hardware implementations

Here Ampere and Volt travels through Fibre network instead of copper wire

Digital Substation - Paradigm shift in Substation Automation

Time synchronization domain will move from mili sec to micro sec

Digital substation can’t be built overnight, its an evolving process

Digital Substation

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Digital Substation - Structure

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3

Station level

Substation control

system like Servers,

HMIs, Gateways, GPS

Supports multiple

clients

Data exchange within

substation as well as

Remote

Bay level

Protection and Control

IEDs.

Interface with field

equipments (SV and

GOOSE)

Interface with peer

devices (GOOSE) &

Station level devices on

“Client-Server” (MMS)

Process level

Substation primary

equipments with

interfacing devices

Analogue signals from

MU to IEDs by Sample

Value

Binary signals from/to

ICU by GOOSE to/from

IEDs

Courtesy: NR

IEC 61850 – 8-1

IEC 61850 9-2 LE

Digital Substations are coming out from concepts to reality

Trend of pilot projects on individual bays - Lot of learning each time

Full fledged Digital substations are being planned of course as pilot project

Few Substations are already built but with lot of efforts to bring down the technology to reality

Still today technology is evolving and not mature enough for easy adoption

Many challenges : Implementations, Maintaining reliability, O&M aspects up to the level of normal substations

Present Scenario

July 26, 2019

At first instance it looks very simplified but, when we really execute it all the complexities experienced

Flow of Presentation – Key Points

1

• Implementations & Learnings - IEC 61850 Substation Automation Domain

2 • Digital Substation Requirements – Latest Standards & Protocols

3 • Limitations and Challenges

4 • World Vide Review (Cigre 2018 Papers)

5 • Utility Concerns with Expectations and Concluding Remarks

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July 26, 2019

Digital Substation

Adoption of other networking and communication standards

IEC 61850 edition 2 adoption

Process Bus pilots with different configurations and complexities

Confidence building with change mind set

Establishment of Network performance

Optimum utilization of IEC 61850 -8-1 Functionalities

Methodical Approach

Implementations & Learning - IEC 61850 Substation Automation Domain

Learning &

Implementations

Learning &

Implementations

New Challenges &

Limitations

Road Map

1

July 26, 2019

Optimum Use of IEC 61850-8-1 Features - GOOSE Application Functions

GOOSE Application Functions

Bus Coupler Bay status

TBC Bay status & Trouble

Transfer Bus Iso. Ladder N/W

LBB Trip Bus

TBC Bay A/R

Intra Bay cabling for

Bay Switchgear

Bay CT, CVT,

Transformer,

RTCC, OLTC

Carrier & Direct Trip Interface - GOOSE Application Functions

July 26, 2019

Scheme

PLCC Panel in C/R

Relay Panel in Yard Kiosk

To avoid long cabling, carrier

interface considered through

soft GOOSE signals by

providing interfacing panel

(PLCC BCU Panel).

Soft GOOSE signals between

Relay and PLCC BCU

Hard wiring between PLCC BCU

& PLCC / FOTE Panel

Control Room

PLCC BCU Panel

PLCC Panel

Control & Interlocking GOOSE

July 26, 2019

Conventional Scheme

Soft Logic through GOOSE

Bus Coupler Bay Status

PT Selection logic – 3 Bus System

July 26, 2019 Soft GOOSE Signals

“Normal-Inter-Transfer” Logic

July 26, 2019

11

Soft GOOSE Signals

GOOSE for Protection Applications

July 26, 2019

BAY-1

MAIN-I

PDIS

MAIN-II

PDIS

BCU

PLCC BCU

PLCC

/FOTE

PANEL

IEC 61850 SUBSTAION LAN

CARRIER SENT GOOSE

CARRIER PROTECTION EVENT

Location-A Main-1 : 125 ms, Main-2 : 61 ms

YARD KIOSK CONTROL ROOM

Issues

Higher GOOSE event timings (even 100 ms)

particularly for Carrier sent event

Inconsistent timings for M-I & M-II of same bay

Location-B Main-1 : 167 ms, 169 ms, 161 ms

MEASUREMENT OF GOOSE EVENT TIMING

July 26, 2019

BAY-1

PDIS

CB Fail

Prot.

BCU

BAY-2

PDIS

CB Fail

Prot.

BCU

BAY- n

PDIS

CB Fail

Prot.

BCU

LBB TRIP GOOSE

Bus-1 / 2 LBB TRIP GOOSE

PUBLISHING

Bus-1 / 2 LBB TRIP GOOSE

SUBSCRIBING

Bus-1 / 2 LBB TRIP GOOSE

SUBSCRIBING

IEC 61850 SUBSTTAION LAN LBB TRIP GOOSE

BREAKER FAIL EVENT

GOOSE for Protection Applications

Initially timings were inconsistent

Duration in hundreds of milliseconds

Discussed with OEM‟s R&D teams.

July 26, 2019

Improvements in System Engineering Aspects

Earlier Configuration

Protection alarm signals for HMI reporting were configured as GOOSE to BCU for latching

functionality of HMI bay view annunciation, instead of MMS messages, due to which network traffic

was increasing, in the event of fault.

Revised Configuration Configuration modified and protection alarm mapped with LED signals of respective IEDs to latch

them and GOOSE messages are reconfigured as MMS messages.

MMS: Manufacturing Message Services (TCP/IP Messages)

Examples of protection alarms – configured as GOOSE

July 26, 2019 15

Improvements in System Engineering Aspects

Earlier Configuration

- Common data sets are

utilized for MMS reporting

to HMI as well as GOOSE

publish

- Data attributes in GOOSE

datasets are time tagged

as selection through data

class (all attributes

selected automatically

including time).

Revised Configuration - Separate Data sets are

configured for GOOSE and

MMS messages

- Instead of selecting “Op”

data class, data attributes of

“quality” and “general”

are selected without

selecting “time”.

July 26, 2019 16

Improvements in System Engineering Aspects

Earlier Configuration Generic logical nodes

were utilized for protection

function GOOSE publish

instead of “Native” logical

nodes adding a process

step before GOOSE

publish. (i.e. all GOOSE

publishing was either

through relay logic or

through virtual output)

Revised Configuration Configuration modified by

utilizing “Native” logical

nodes of respective

protection functions for

GOOSE publish

July 26, 2019

66KV Bus bar Protection through Reverse Blocking GOOSE

BC IED

INCOMER-1

O/C FUNCTION HIGH

INCOMER-2

O/C FUNCTION HIGH

66KV BUS-2

66KV BUS-1

IED IED IED IED

IED IED

O/C - E/F FUN. HIGH

O/G-3 O/G-4

DIR. CONFIRMATION

GOOSE FROM B/C

BLOCKING GOOSE

FROM FEEDER

& NO TRIPPING

Only O/G Feeder on which Fault is there will Trip

Fault On Feeder

IED

IED

BAY NOT TRIPPED

BAY TRIPPED

O/G-2 O/G-1

O/G-2 O/G-1

July 26, 2019

BC IED

INCOMER-1

O/C FUNCTION HIGH

INCOMER-2

O/C FUNCTION HIGH

66KV BUS-2

66KV BUS-1

IED IED IED IED

IED IED

O/C-E/F FUN. HIGH

O/G-3 O/G-4

DIR. CONFIRMATION

GOOSE FROM B/C

NO BLOCKING

GOOSE FROM FDR

&

TRIP TO B/C & ALL

BAY ON BUS-1 AFTER

TIME DELAY

All Feeder on Bus-1 Including I/C & B/C Will Trip

Fault On Bus Bar

TR

IPP

ING

GO

OS

E

IED

IED

BAY NOT TRIPPED

BAY TRIPPED

66KV Bus bar Protection through Reverse Blocking GOOSE

O/G-2 O/G-1

220kV AIS Line Bay GUI

Interlock permissive status

Useful in troubleshoot

220kV Hybrid Line Bay GUI

July 26, 2019 20

July 26, 2019

Scheme Phase Wise modality

Phase-I Phase-II Phase-III

LBB scheme of Main

Protection Relay

Hard wired Soft scheme through

GOOSE for 66KV also i.e.

where there is no

redundancy

Soft scheme through

GOOSE only where

redundant LBB (i.e. Bus bar

& Main Protection

LBB - 220 & 400KV)

Carrier Interface

scheme

Hard wiring with PLCC

Panel

Soft GOOSE signals up to

PLCC BCU &

Hard wiring from PLCC

BCU to PLCC Panel

Soft GOOSE signals up to

PLCC BCU &

Hard wiring from PLCC BCU

to PLCC Panel

Trip Transfer scheme Hard wired through NIT

multiplication relays

operated through physical

switch

Soft NI-IT position

configuration against

respective IED contacts

Hard wired through NIT

Multiplication relays operated

through BCU Output

contacts

TBC Bay Input to

Transferred Bay IEDs

Hard wired scheme Soft signals through

GOOSE

Soft signals through GOOSE

N-I-T Position Physical switch Soft Switch only Status

(HMI)

Soft Switch

with Control

(HMI)

A/R In-Out Physical switch Soft Switch

(HMI)

Soft Switch

(HMI)

Carrier In-Out Physical switch Soft Switch

(HMI)

Soft Switch

(HMI)

Implementations based on Leanings

July 26, 2019

As per IEC 61850 standard there are different GOOSE performance class

for different applications. But, such selections are not available in products.

Only priority settings of 0 to 7 is there but it has hardly any significance in

context to network performance.

Limitations of IED GOOSE subscription capability, many a times limits the

GOOSE applications based functionalities

Limitations in Nos of logics that can be configured in respective IEDs so as

to not to affect the performance of IEDs restricts the applications based on

communication

Limitations Faced

Process Bus Implementation – Pilot project

Salient Features Optical CT in series with

existing CT

Process bus (IEC 61850-9-

2LE) compatible relay

MiCOM P444 in separate

panel along with HMI & EFS

in Panel

Output of optical CT is

routed to merging unit

(NXMU) through cable

management box

Analogue VT Input routed to

Merging unit (NXMU)

SV output of NXMU routed to

Distance Protection relay

through EFS

Main-I relay also connected

to EFS and synchronized on

SNTP for analysis

Metering is also done

through Optical CT by

converting Optical output to

Analogue as meters are

conventional

First of its kind in India

Commissioned on 21.06.12

July 26, 2019

220kV Jambuva

Process Bus - Pilot Project – Asoj – MU & SCU

Salient Features

Spare protection class CT

core of existing CT and

protection class CVT core

are routed to Merging Unit

Switchgear Control Unit for

Isolator and CB

Process Bus (IEC 61850-9-

2LE) compatible Main-II

Distance protection Relay in

Panel along with EFS & HMI

SV output of MU routed to

Distance Protection relay

through EFS

Communication between

SCU & Distance Relay is

through GOOSE for Status,

Monitoring, Control &

Interlock

Time Synchronization of MU

& SCU is through 1PPS on

F.O.

Time Synchronization of

existing & New relays along

with HMI through SNTP

Commissioned in July 2014

After this pilots, to go for full fledge Digital S/S, interacted with all OEMs. But, outcome was :Technology is not yet matured. So gone for another pilot with different modality.

Process Bus Pilot Project – Modasa – MU & SCU With CT Core Splitting

Salient Features Process Bus (IEC 61850-9-

2LE) compliant M-I, M-II

BCU in parallel to existing

IEDs

Spare protection class CT

& PT core routed to

Merging Unit

Splitting of single CT core

for multiple IEDs (i.e. BCU,

M-I & M-II) through EFS

Switchgear Control Unit for

Isolator and CB in

switchyard

Communication between

SCUs & IEDs is through

GOOSE for Status,

Monitoring, Control &

Interlock

Time Synchronization of

MU latest std. IEEE 1588 v2

Time Synchronization of

IEDs through SNTP

At Process level Bus

topology with PRP (Unique)

SAS (8-1) Panel Process Bus (9-2 LE) Panel

The core idea of the pilot project is to,

- Adopt totally new approach by developing communication interfaces

at process level by forming Bus (Process Bus) topology instead of point

to point topology (generally adopted)

- Include all other complex and mandatory standards/concepts/

technologies envisaged for full-fledged digital substation.

Final Configured Architecture

PRP at

Process

level

Redundancy

Box to

Connect

Digital bay

PRP network

to existing

main SAS

Non PRP

Network

Bus

Topology

Engineering Aspects

Development of SCU interfaces with other SCUs, IEDs as well as HMI

Development of Merging Unit interfaces with IEDs

Sr.

No.

IED BCU

GOOSE

Main-I

GOOSE

Main-II

GOOSE

SCU-1

GOOSE

SCU-2

GOOSE

SCU-3

GOOSE

HMI

MMS

1 SCU-1 √ √ × -- √ √ √

2 SCU-2 √ √ √ √ -- √ √

3 SCU-3 √ √ √ √ √ -- √

Sr.

No.

IED SV

Subscription

Current Bus Voltage Line Voltage

1 BCU MU-1 MU-2

(Metering)

MU-2

(Metering)

2 Main-I MU-1 MU-1

(Protection)

MU-2

(Protection)

3 Main-II MU-1 MU-1

(Protection)

MU-2

(Protection)

MU: Merging Unit

SV: Sample Value

MU Sample Value Subscription Matrix

SCU Communication Interface Matrix

Mo

re t

ha

n 2

00

GO

OS

E .

MU-1: 4 CT, 4 VT

MU-2: 0 CT, 8 VT

July 26, 2019

Time Synchronization accuracy requirement of process bus is very stringent ( i.e. in terms of µs) than station bus (ms) as; 80 Samples/Cycle means - 250 µs per sample and 4.5 Deg. Per sample.

Criticality for Process Bus Applications

July 26, 2019

To meet the above stringent requirements 1. Time Sync on 1pps / IRIG-B on F.O./ IEEE 1588v2 2. Gigabit Ethernet with Multicast filtering

45 Deg.

Sample Value frame size 122 bytes.

At 50Hz Bandwidth 3.9 Mbit/s (122*8*4000).

Simply consider 10 Merging Units - bandwidth @40 Mbit/s

Multicast traffic filtering (i.e. VLAN, Multicast MAC filters) is

mandatory

Challenges and Learning

Issue

Subscription of Sample Value

from two different MUs leading to

inaccuracy in measurement and

malfunctioning of IEDs

Mitigation

Out of two modes of time IEEE

1588v2 time synchronization PTP

profile (Peer to Peer and End to

End), Peer to Peer was selected by

default. It was changed to End-to-

End (E-2-E) profile and

measurement got normalized

Challenges and Learning

Issue

Blocking of communication of 8-1 port

of M-II IED as soon as connected to

process bus port

Mitigation

While analysis, it was observed that,

Sample value data stream was

blocking the communication of 8-1

port. Hence it was decided to

configure VLAN to segrigate 8-1 and 9-

2 traffic.

With VLAN, Main-II IED 8-1

communication got normalized

July 26, 2019

Challenges and Learning

July 26, 2019

Issue

Inhibiting Sample Value

subscription in case of satellite

tracking problem of GPS

Mitigation

There are three types of configuration modes

for MUs. « No sync », « Local Sync » and

Global Sync »

Default configuration was of „No sync‟ in

case of loss of „Global sync‟ to MU. It is

changed to „Local sync‟. Thus as time

synchronization signal will still be available

to MU from GPS internal clock. Thus SV

subscription was normalized.

Also, „9-2 LE SAV Alarm‟ configured in IEDs

to capture the tracking problem .

Challenges and Learning

Issue

Blocking of operations of M-II IED

though subscribing sample value

correctly

Mitigation

Sample value subscription by M-II IED

was there but actions found blocked.

After detailed analysis, it was identified

that, 1pps time synchronization signal

also needs to be provided over and

above SNTP .

Accordingly, 1pps time sync signal is

provided to M-II IED, it started

exhibiting. Thus, functionality

normalized.

All these experiences and learning helped OEMs as well as Utilities in

their subsequent projects based on Process Bus technology

July 26, 2019

Parallel Redundancy Protocol (PRP) topology at process level seems mandatory

VLAN configuration and MAC address filtering configuration is also important to segrigate 8-1 and sample value traffic and thereby to achieve required network performance.

Variant capability in Merginng unit seems very useful to achieve various functionality involving multiple CT-PT-CVT signals as it reduces requirement of Merging Units

Time Synchronisation accuracy and consistancy is first and foremost requirement for sample value publishing as well as subscription. Hence network based protocol IEEE1588 v2 along with redundancy seems absolutely mandetory

On line test facilities with virtual isolation will be very useful as there will not be any physical isolation in process bus applications

IEC 61850 Edition 2 developments seems extremely useful and needs to be considered

Outcome of the Project

July 26, 2019

IEC 61850 series

Standard 8-1 for station Bus and Standard 9-2 for process Bus IEC 61850-9-2LE Implementation guidelines for process Bus IEC 61850 Edition 2

IEC 61869 series

IEC 61869-9 for Merging Units and Non Conventional IT

IEC 61869-13 for Stand Alone Merging Unit

IEC 62439-3 for Seamless redundancy (PRP & HSR Protocols) Parallel Redundancy Protocol High Availability Seamless Redundancy

IEEE 1588 or IEC 61588 for Precision Time synchronization Protocol

IEC C37.2011 PTP Power profile for hardware based time stamp

Cyber Security Standards NERC CIP IEEE 1686

IEC 62351

Digital Substation Requirements – Latest Standards and Protocols

July 26, 2019

2

Communication

Network Configuration

Time Synchronization

Key Standards

IEC 61850 Edition 2 Developments

Network Engineering Guide Lines Courtesy ABB

Virtual Isolation : Mechanism for testing, simulation and maintenance

Benefits : Testing of function parts in running system

Standardized application for test and test-blocked mode

Enables more efficient testing and maintenance

Provision of Simulation Bit:

Benefits : Provision of simulation bit for GOOSE and Sample value

Means facility for on line testing of P & C applications

SCL Implementation Conformance Statement (SICS):

Developments in IEC 61850 Standard

July 26, 2019

Developments in IEC 61850 Standard

New System Logical Nodes

Courtesy OMICRON

Subscription monitoring : per GOOSE and per Sample value

July 26, 2019

Learnings outcomes based on past projects

All Latest Standards and

Protocols

Learning & Outcomes of the Process Bus Pilot

projects

Network Performance criteria for GOOSE & SV

Cyber Security

IEC 62439-3 PRP for GPS

IEC 62439-3 PRP at Process Level

IEC 62439-3 PRP at Station Level

Variant capability of Merging Unit

IEEE 1588v2 & PTP Power profile

IEC 61850 Edition 2 developments

Redundancy of Merging Units

Digital Substations – Technical Requirements

Considerations for Digital Substations

Considerations

PRP – Parallel Redundancy Protocol

39

A Full Fledged Digital Substation - 220/66kV

July 26, 2019

Detailed

Architecture

PRP On Process Bus : For some OEMs products still under development and

proposing alternate solutions with Redundancy Box

Redundancy Box may attract following; Latency to time critical messages - Test report showing <20 µs

Latency for time synchronization - Can act as transparent clock

Network monitoring through Red box - Can be achieved

Time Sync : For some OEM

IEEE 1588 v2 not available for Merging Unit

Alternately proposing IRIG-B/1pps on F.O. adding complex & components

Recently developed

Decentralized Bus Bar :

All OEM do not have

Alternately Centralized Bus bar scheme is proposed

Configurations and architecture varies from OEM to OEM

Limitations and Challenges

July 26, 2019

Product Front

3

Transient behaviour of Merging Unit : Critical when subscription of sample value from multiple Merging Unit

IEC 61869-9 covers this. It was uptil in draft mode

Now defined in IEC 61869-9 standard

But products still commercially not available

LGOS & LSVS : It is an optional requirement of the standard. Hence some OEM

and Other LNs do not have it but, articulates different way to meet functionality

Duplicate GOOSE : All OEM do not follow detection of “Sq No” & “St Num” and

may impact “On Line” testing

Lack of standard procedure for NCIT testing Metering through process bus is still a matter of concern Different OEMs have different methodologies for Sample Value issues like; √ Countermeasures for Loss of Sample Value,

√ Re sampling etc.

√ May lead to errors / mal operation if not taken care properly when system has multivendor IEDs

Limitations and Challenges

July 26, 2019

Technology Front

NCIT – Non Conventional Instrument Transformer

Many western countries are still going for pilots as some or other challenges like;

Though standard defines 80 s/c, but Nos of stream IED can read is limited to process algorithm and are different for different OEMs

During CB synchronization test it is observed that sampling time delay is different for different OEM due to flexibility in standard IEC 61869-9. It defines only maximum time delay which shall be < 2 ms (i.e. 36 Deg angular deviation for 80 s/c)

Though edition 2 defines SICS but, lack of interoperability due to varying implementation of SCL because of flexibility of standard

IED from some vendor are not able to publish GOOSE with data “quality” causing issues during site testing on “Test mode”

RSTP did not worked in combination with PTP. Blocking and forwarding multicast link layer messages of PTP. Standard says messages must not be blocked.

Utilization of Resilient Ethernet Protocol (REP) Non working of PTP (Precision Time Protocol) power profile with Ethernet Switch having RedBox functionality Use of End to End profile instead of Peer to Peer profile

To scale the technology it is necessary to develop;

- Generic requirement of NCIT - Information processing algorithms - Principles of building digital network - Maintenance aspects - Appropriate changes in Regulatory and technical documentation

Review Of World Vide Practices – Cigre 2018 Papers

July 26, 2019 SICS – SCL Implementation Conformance Statement

4

National Grid UK

Statnett Norway

Russia

Process Bus Architecture has many variants what philosophy to adopt?

While adopting Process Bus new challenges and limitations being faced each time

Testing and Monitoring of Process Bus system

Maintenance aspects

Skill level

IEC Study committee/WG should

Address these issues and derive clear implementations guide lines

Make various optional requirements in standards mandetory to bring all OEMs at common platform

OEMs should be ready with products compliant to latest standards including common solutions for actual implementation covering present limitations / challenges

Utility Concerns & Expectations

July 26, 2019

Concerns

Expectations

5

Building of competence level at OEM as well as user end is first and foremost requirement for moving further in Substation Automation domain

Need arise to establish national level forum of industry stake holders (i.e. User, OEMs as well as laboratories) to derive;

a) Common Implementation guidelines as best practices b) Future roadmap in Substation Automation domain based on latest developments, availability of products as well as conformance testing

Development in this direction will make the whole process simpler and easily adoptable

Benefits of the technology can be availed only and only if it is adopted with holistic approach and long term planning

It will have significant impact on O&M as well as life cycle management aspects

Conclusion

July 26, 2019

July 26, 2019

We have achieved “One India One Grid”

Its time to focus on “One India One Scheme” in the benefit of Industry

Thank You

Today there are many variants in secondary schemes in different Utilities

With Automation these variants are increasing

With process Bus these variants will increase in uncontrolled way as technology itself has many variants

Lot of skilled man-hours are invested in engineering & approvals

This needs to be diverted in adopting new technologies and deriving common guidelines