POWERGRID CORPORATION OF INDIA LIMITED

PROJECT REPORT ON SYSTEM PROTECTION SCHEMS IN WESTREN REGION

-SK.MASTANVALI

EMP.NO:02985

ET-19TH BATCH

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INDEX

S.NO CONTENTS PAGE.NO

1 INTRODUCTION 2

2 SYSTEM PROTECTION SCHEMS AT APL 3

3 SYSTEMPROTECTION SCHEMS ON GWALIOR AGRA D/C 6

4 SYSTEM PROTECTION SCHEMS AT BALCO 8

5 SPS AT ESSARMAHAN 9

6 SYSTEM PROTECTION SCHEMS AT TIRORA 10

7 SYSTEM PROTECTION SCHEME (SPS) FOR SYNCHRONIZATION OF NEW GRID AND SR GRID 13

8 SPS AT HIGH FREQUENCY 20

9 SPS AT SASAN 21

10 APPENDIX 22

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INTRODUCTION

System protection schemes (SPS) are meant to protect power system from

major shocks and to prevent major grid disturbances like cascading trippings and local

& global blackout. Unlike unit protection schemes which are meant it monitor

particular parameters related to certain equipment or line, these protection schemes

monitor various parameters of system that may be located geographically different

locations through a communication network. SPS activates contingency measures

based like load shedding, generation back down to control loading on other lines

based on the inputs and settings.

The operation of SPS controls the loading on lines and saves the system from

critical situation. However system operator ensures system operating in safe limits

through strategic control actions and wants to avoid the SPS operation.

Non-Operation/Mal function of SPS is a major problem which has to be taken

care of immediately. So it is very important to for control room operator to have a

brief knowledge of various SPS and their settings.

In this project the content of SPS is improved with the addition of logic

diagrams to give a quick and better understanding of operation. The advantage of

logic diagram interface is, easy understanding and it can be easily converted as

program. It may be further improved in future, real time data fed to the logic to test

the correct operation of SPS and to give an indication at RLDC end.

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1.SYSTEM PROTECTION SCHEMS AT APL

Adani Power Ltd, Mundra (4x330MW+5x660MW) has its generation and transmission Scheme in 3 stages.

The generation at APL, Mundra is as follows:

Stage 1: 4X330MW=1320MW Stage 2: 2X660MW=1320MW

Stage 3: 3X660MW=1980MW

The associated transmission scheme is as follows: Stage 1:

220kV Mundra-Nanikhakhar D/C

220kV Mundra-Tappar D/C

400kV Mundra-Hadala S/C 400kV APL-Versana-Hadala S/C

400kV Mundra-Sami-Dehgam D/C

Stage 2: 400kV Mundra -Zerda 2X D/C

Stage 3:

2X1250MW +/- 500kV APL,Mundra-Mohindergarh HVDC bipole. LILO of 400kV Bahadurgarh(PG)-Bhiwani (BBMB)

400kV Mohindergarh-Danauda D/C

400kV Mohindergarh Bhiwani D/C

• All the generating units are synchronized and the transmission lines of stage-1 and Stage-3 are only commissioned.

• SYSTEM Protection Scheme was commissioned by APL for mitigating any contingency out of any

ckt tripping or overloading of lines. • Triggering the trip is initiated by activation of respective stages of Over current relay used for line

protection

SPS Logic for 400kV Mundra –Versana/Hadala

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SPS logic for 400kV Mundra-Sami 1&2 and 400kV Sami-Dehgam 1&2

Current=Current in any line of above lines

Power=Power in any line of above lines

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SPS for 220kV Mundra-Nanikhakar 1&2 and 220kV Mundra-Tappar 1&2

Current=Current in any line of above lines

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2.SYSTEMPROTECTION SCHEMS ON GWALIOR AGRA D/C

During the scenario of heavy import by NR from Western Region, simultaneous tripping of 765kV

Agra-Gwalior circuit-I & II or tripping of 765 kV Bina-Gwalior Ckt-I & II results in rush of power on

parallel interconnections of NR with WR and ER. The contingency results in heavy overloading of

network in Western region (especially in Gujarat) as well as in Eastern region with critically low

voltage in the large part of ‘NEW’ grid.

Therefore, an SPS for shedding loads in western UP, Rajasthan, Punjab & Haryana area subsequent to

sudden large reduction of import at 765kV Agra (from WR) would help in minimizing the impact of

contingency. If the actual import on the 765kV Agra Gwalior D/C is more than a certain level,

automatic backing down of generation in the WR would also be desirable

SPS on 765KV Gwalior-Agra D/C

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SPS for sudden loss of import by NR on Agra-Gwalior-Bina lines

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3.SYSTEM PROTECTION SCHEMS AT BALCO

The interim evacuation of BALCO generating plant (2x67.5+4x300MW) is approved through LILO of

400kV Korba-Birsinghpur one ckt at BALCO, Chhattisgarh till commissioning of Dharamjaygarh

pooling station. The margin for scheduling through STOA/PX from the BALCO units would be limited

by the W3 injection TTC declared by NLDC and is available in NLDC/WRLDC website.

SPS on 400kV Balco-Brishingpur line

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4.SPS AT ESSARMAHAN

The interim evacuation of Essar-Mahan generating plant (2x600MW) is approved through LILO of

400kV Korba-Vindhyachal one ckt at Mahan, M.P till commissioning of Mahan-Bilaspur D/C lines.

Till commissioning of Bilaspur lines, the margin for scheduling through STOA/PX from Essar-Mahan

unit would be limited by margin declared by WRLDC after system studies. It is proposed to

implement a system protection scheme before commissioning of first 600MW unit.

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5.SYSTEM PROTECTION SCHEMS AT TIRORA

Tirora,is a generating station in Maharashtra with capacity of 3300MW(5X660MW).

It is connected to Western grid via 400KV Tirora-Warora-Wardha D/C and 765KV Tirora-Akola S/C bypassing 765KV Koradi

The scheme shall aim to reduce the generation at Tirora in case of over loading of both sections of

line between Tirora-Warora and Warora-Wardha. The output derived from operation of over current protection of Warora-Wardha line at Warora end

shall be carried forward to Tirora by using spare channels from PLCC link between Warora and

Tirora.

SPS For 400kV Tirora-Warora D/C

Power = Power in any one line of D/C

Current= Current in any one line of D/C

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SPS AT 765/400KV TIRORA FOR WARORA -CHANDRAPUR-II D/C

WRLDC has declared Wardha flowgate (2480MW) comprising of the following lines:

- 400KV Wardha-Akola D/C

- 400KV Wardha-Parli D/C

APML,Tirora is connected to 400KV Wardha via 400KV Tirora-Warora-Wardha D/C. With the

commissioning of 400KV Warora- Chandrapur-II D/C, major portion of the tirora generation flows

over these ckts. Tripping of 400KV Warora- Chandrapur-II D/C will critically load the Wardha

flowgate and therefore SPS was suggested in case of tripping of 400KV Warora-Chandrapur-II D/C.

SPS AT 765/400KV TIRORA FOR AKOLA-II ICT OVERLOAD

To control overload of 765/400KV Akola-II ICT,Loading of 765KV Tirora-Koradi-Akola one ckt is

monitored

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SPS at 765/400KV tirora for Overloading of Lines

at Akola Sub-station

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6.SYSTEM PROTECTION SCHEME (SPS) FOR SYNCHRONIZATION OF

NEW GRID AND SR GRID

SPS1:

Loadshed(SR): Gen.Backdown:

S.no State Quantum S.no Generator Quantum

1 Tamilnadu 146 MW 1 JPL 150 MW

2 Kerala 125 MW 2 JPL Extn 150 MW

3 Karnataka 104 MW 3 KSK 100 MW

4 Andhra Pradesh 125 MW 4 LANCO 100 MW

TOTAL 500 MW 5 DB Power 100 MW

6 KWPCL 100 MW

7 BALCO 50 MW

8 NSPCL 50 MW

TOTAL 800 MW

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SPS3:

Loadshed(SR):

S.no State Quantum

1 Tamilnadu 146 MW

2 Kerala 125 MW

3 Karnataka 104 MW

4 Andhra Pradesh 125 MW

TOTAL 500 MW

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SPS4:

Loadshed(SR): Gen.Backdown:

S.no State Quantum S.no Generator Quantum

1 Tamilnadu 146 MW 1 JPL 150 MW

2 Kerala 125 MW 2 JPL Extn 150 MW

3 Karnataka 104 MW 3 KSK 100 MW

4 Andhra Pradesh 125 MW 4 LANCO 100 MW

TOTAL 500 MW 5 DB Power 100 MW

6 KWPCL 100 MW

7 BALCO 50 MW

8 NSPCL 50 MW

TOTAL 800 MW

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SPS5:

Loadshed(SR): Gen.Backdown:

S.no State Quantum S.no Generator Quantum

1 Tamilnadu 290 MW 1 Tiroda 200 MW

2 Kerala 135 MW 2 Mauda 100 MW

3 Karnataka 195 MW 3 Koradi 70 MW

4 Andhra Pradesh 230 MW 4 Kaparkheda 150 MW

TOTAL 800 MW 5 Chandrapur 100 MW

6 IndiaBulls 100 MW

TOTAL 800 MW

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SPS6:

Loadshed(SR): Gen.Backdown:

S.no State Quantum S.no Generator Quantum

1 Tamilnadu 290 MW 1 JPL 150 MW

2 Kerala 135 MW 2 JPL Extn 150 MW

3 Karnataka 195 MW 3 KSK 100 MW

4 Andhra Pradesh 230 MW 4 LANCO 100 MW

TOTAL 800 MW 5 DB Power 100 MW

6 KWPCL 100 MW

7 BALCO 50 MW

8 NSPCL 50 MW

TOTAL 800 MW

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SPS7:

SPS8:

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SPS9:

SPS10:

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7.SPS AT HIGH FREQUENCY

Automatic generation tripping in Western Region at high frequency (51.5 Hz) to help arresting the

rise of frequency in case of islanding of WR from rest of NEW grid is as follows

Gen.Backdown(WR):

S.No. Gen.Station Trip Unit no. Unit capacity(MW) Delay(Sec)

1 Korba(NTPC) 7 500 30

2 Vindhyachal 7 500 30

3 CGPL 40 830 30

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8.SPS AT SASAN

Sasan UMPP (6X660MW) is connected to WR grid via:

• 765KV Sasan-Satna D/C

• 765KV Sasan-Vindhyachal PS-Satna S/C

• 765/400KV 2X1000MVA ICTs

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APPENDIX

Digital Logic gates:

OR Logic:

Logic table

Inputs Output

x y Z

0 0 0

0 1 1

1 0 1

1 1 1

AND Logic:

Logic table

Inputs Output

x y Z

0 0 0

0 1 0

1 0 0

1 1 1

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Ex-OR Logic:

Logic table

Inputs Output

x y Z

0 0 0

0 1 1

1 0 1

1 1 0

NOT(Negation):

(Symbol of Negation)

Logic table

Input Output

x x

0 1

1 0

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Multiplexer/Mux:

Logic table

Input Output

X Y

0 A

1 B

Comparator:

If Input ≥ Setting, Output = 1, Else 0 (zero)

Multi Input Comparator:

If Any one of Inputs ≥ Setting, Output = 1, Else 0(zero)

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Delay/Timer:

If Input =1 Continuously for T Sec then Output=1, Else 0(zero).

THE END

Thank you