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~~~Central Electricity Authority

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Western Regional Power Committee'% -3, ~.~ a}::r, ~iliT (¥), ~ - 400093

F-3, MIDC Area, Andheri (East), Mumbai - 400 093~qrq Phone: 022-28221681,2820 0194, 95, 96 ~ Fax: 022-2837 0193Website: www.wrpc.gov.in E-mail: comml-wrpc@nic.in

WRPC/PCM/SPS/'LO'S{ ill. 4-9

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.9001-2008IS/ISO: 9001-

2008

To,

As per mailing list

Subject: Meeting for framing protocol for protection relaying system as per CERCorder dated 05.08.2015 and approval of modifications to Agra- Gwalior SPS

suggested by NLDC

Sir,

Honourable CERC vide order no 009jSMj2015 dated 05.08.2015, has directed RPCs tobring out a protocol for ,checking the relay settings, ensuring health of the existingprotection system and peroidicity of carrying out this exercise. A copy of relevantextracts of the above order is enclosed herewith for ready reference.

Also, NLDCvide letter dated 07.09.2015(copy enclosed), has proposed m'difications inthe existing Agra Gwalior SPS in view of commissioning of double circuit 765kV Gwalior_ Jaipur(Phagi) and 765kV Phagi- Bhiwani circuit.

To discuss the above issues, a meeting will be held on 16.10.2015 at 11:00 hrs atWRPC,Mumbai. You are requested to make it convenient to attend the meeting.Enclosed: As above your;ji/'r!!!IlY,

satyZan.sSuperintendent Engineer(P)

Copy to;- ED, NLDC, POSOCO, New Delhi.You are requested to depute a representative for the meeting

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MAILING LIST

1. D.G.M. (O.S. ),N.T.P.C., Mumbai, Fax- 282166922. DGM (O.S.), WRLDC, Mumbai Fax-28235434

3. DGM, WRTS-I, PGCIL, Nagpur, Fax- 0712- 2631051 16413664. AGM, WRTS-II, PGCIL, Baroda Fax-0265-2480952 (Tele fax:

2487542)5. GM, CGPL, Mundra Fax.No. 028386611886. S.E.(T&C), MSETCL, Vashi Fax- 022-27656039/276534637. S.E. (Testing), GETCO, Baroda. Fax-0265-23512188. E.D. (T&C), MPPTCL, Jabalpur. Fax-0761-27027109. D.G.M. (O.S. ),N.T.P.C., Mumbai, Fax- 2821669210. DGM, WRTS-I, PGCIL, Nagpur, Fax- 0712'-2631051/64136611. AGM, WRTS-II, PGCIL, Baroda Fax-0265-2480952 (Tele fax:

2487542)12. AGM (QAIT), TPC, Trombay. Fax -022~6668708813. Vice President, APL, Ahmedabad 079-2555717614. GM, CGPL, Mundra Fax.No. 02838 661188

Petition No. 009/SMJ2015

CENTRAL ELECTRICITY REGULATORY COMMISSiONNEW DELHi

Coram:Shri Gireesh B. Pradhan, ChairpersonShri A. K. Singhal, MemberShri A. S. Bakshi, Member

3. Shri Hernant Sharma, CMD, GRIDCO

Date of order: 5.8.2015

in the matter of:Fo!lowing up actions on the recommendations of CAC Sub-Committee onCongestion in Transmission

ORDER

The Central Advisory Committee (CAC) had in its meeting held on 12.5.2014

decided to constitute a sub-committee from amongst the Members of the CAC to

examine issues connected with congestion in transmission. The Sub-Committee on

Congestion in Transmission was constituted by CERC vide letter dated 11.7.2014,

with the foliowing:

Members:

1. Shri R.V. Shahi, Former Secretary, Ministry of Power-Chairman

2. Shri Ashok Khurana, Director General, Association of Power Producers

4. Shri R.N. Nayak, CMD, POWERGRID

5. Shri Vijayanand, CMD, APTRANSCO

6. Prof. S.C. Srivastava, ilT Kanpur

7. Shri Pankaj Batra, Chief Engineer (!/C)- FC&A, CEA

. ·S. Shri Ravinder Gupta, Director (SP & PAl, CEA

9. Shri AK. Saxena, Chief (Enqq.), CERC- Convenor'\ •.\~ "v

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Page 1 cf 9

NLDC for siting and sizing of Phase Shift Transformer (PST). (Para 3.2.3)

(D)Action to be taken by PGCIL:r

(1) POWERGRID may carry out a comprehensive study jointly with CEA and

(E) Action to be taken by Member Secretary (RPCs):

(1) Protection Sub-committee of RPC should bring out a protocol for checking the

settings, ensuring healthiness of existing protection system and periodicity of

carrying out this exercise. (Para 6.8)

(F) Secretary, Forum of Regulators:

"(1) TTC/ATC to be declared by STUs for state network in planning horizon aswell as operating horizon (Para 5.3.2). Operational feedback by SLOCs to STUs bemade mandatory through appropriate Regulations (Para 8.4.5)."

5. All orqanizations/entities as noted above shall take necessary follow up

actions in a time bound manner on the points shown under them and submit. ------

quarterly 'action taken report' to the Commission within 15 days from the end of the

quarter to which the report pertains~

Sol(A. S'. Bakshi]

Member

Sa!(A. K. Singhal)

Member

Y<y(Gireesh B. Pradhan)

Chairperson

~.~:;..-/j//':1

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CERTIFIE:; 'i"'RUECOpy~"",c;i.' 1)"""-

Authorlsed Si,gna,to-tyC.E.R.C.

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A« ., Petition No. 009/SM/2015 Page 9 of9

1

Modifications Suggested in SPS settings on WR-NR Corridor in view of

2 * 765kV Gwalior – Phagi S/C and 765kV Phagi-Bhiwani S/C

7th Sep 2015

Prior to August 2015, Northern Region (NR) and Western Region (WR) were connected

through two 765 kV lines, two 400 kV lines, four 220 kV lines and two HVDCs. Considering

the weak AC interconnection between WR-NR corridor in case of tripping of both the 765kV

Gwalior-Agra circuits, System Protection Schemes (SPS) were installed on 2 * 765kV

Gwalior – Agra S/C for smooth transfer of power from Western Region to Northern Region.

Transfer capability of WR- NR corridor had been limited by 1250 MW SPS setting on 765kV

Gwalior-Agra S/C and the same has been revised to 1400 MW recently. Both the circuits of

765kV Gwalior-Jaipur (Phagi) have been recently commissioned along with 765kV Phagi-

Bhiwani circuit. Considering the commissioning of above 765kV lines, Power flow studies

have been carried to assess the WR-NR corridor transfer capability.

Assumptions in Base-case Power flow study are as follows:

Western Region

a. Generation: 47129 MW

b. Demand: 39774 MW

Northern Region

a. Generation: 37655 MW

b. Demand: 41504 MW

Power flow on Mundra-Mohindergarh HVDC: 2000 MW.

Power flow on Vindhyachal BTB HVDC is considered as 250 MW from WR to NR.

Vindhyachal Unit-12 (1x500 MW) is considered as connected to Northern Region.

Maximum permissible loading considered for 765 kV lines is 2750 MW under (n-1)

contingency.

Maximum permissible loading considered for 400 kV lines under (n-1) contingency is

thermal limit.

2

Assessment of WR-NR Transfer capability:

Procedure given in the CERC congestion charge regulations are followed for the

assessment of transfer capability i.e., loads in Northern Region are increased and

generation in Western region is increased. Before increasing the load in NR, the drawal of

Punjab and drawal of Uttar Pradesh are taken as follows:

As declared on NLDC website, Punjab drawal is considered as 6200 MW.

As declared by UPPTCL on its website, UP drawal is considered as 7100 MW.

However, it appears to be on higher side as constraints are faced at many places

mentioned below:

a. (n-1) loading limit violation at Agra(UP) ICTs etc.

b. (n-1-1) contingency of 400kV Agra (PG)-Agra (UP) D/C leads to less than

the Emergency voltage mentioned in CEA Transmission Planning Criteria

(TPC) 2013 at Agra (UP).

Based on the above assumptions, the load flow studies has been carried out. It has been

observed that with the present load-generation balance, WR-NR transfer capability comes out

to be 7700 MW and the limiting constraint would be 2750 MW loading on 765kV Gwalior-

Agra line under (n-1) contingency of second 765kV Gwalior-Agra line. Depending on

different Load-generation balance and network topology, transfer capability figure would

vary from 7500 MW to 8000 MW. Flow on WR-NR inter-regional lines in 7700 MW

limiting case is as follows:

TO ZONE 3002 WR

X---- FROM ZONE BUS ----X X----- TO ZONE BUS -----X

BUS# X-- NAME --X BASKV BUS# X-- NAME --X BASKV CKT MW MVAR

124025 MAHIN_HV 400.00 314013 MUNDRA 400.00* 2DC -1002.9 -505.9

124025 MAHIN_HV 400.00 314013 MUNDRA 400.00* 2DC -1002.9 -505.9

154038 VINDHYBT 400.00 324030 VINDHYACHAL 400.00* 2DC -125.1 -43.6

154038 VINDHYBT 400.00 324030 VINDHYACHAL 400.00* 2DC -125.1 -43.6

132022 SAKATPUR 220.00 322040 BADOD 220.00* 1 -13.9 20.7

132032 MODAK 220.00 322089 BHANPURA 220.00* 1 3.3 -13.4

134021 BHINMAL 400.00 314017 ZERDA 400.00* 1 -168.4 22.0

134022 KANKROLI 400.00 314017 ZERDA 400.00* 1 -115.1 36.6

137000 PHAGI 765.00 327003 GWALIOR 765.00* 1 -659.1 171.1

137000 PHAGI 765.00 327003 GWALIOR 765.00* 2 -644.3 178.6

154057 RIHAND-G 400.00 324037 VCHAL-12 400.00* 1 -450.0 148.9

154060 AURYA2 220.00 322032 MALNPUR 220.00* 1 -32.0 26.8

154060 AURYA2 220.00 322033 MEHGAON 220.00* 1 -6.1 29.0

157007 AGRA-PG 765.00 327003 GWALIOR 765.00* 1 -1655.3 130.1

157007 AGRA-PG 765.00 327003 GWALIOR 765.00* 2 -1669.7 128.9

TOTAL FROM ZONE 1000 TO ZONE 3002 -7666.8 -219.7

3

The flow on 2*765kV Gwalior-Agra S/C would be in the range of 3300 MW to 3500 MW

under 7900 MW limiting case. Considering the above, certain modifications would be

required in the existing SPS. The table below gives the modifications required in the existing

SPS.

It is important that the relief indicated in the SPS is available considering the huge quantum

of power flows from WR to NR. The present inadequate relief from this SPS is also the

subject matter of petition no 008/SM/2015 before the Hon’ble Commission.

Further, all the four 765 kV lines from Western Region to Northern Region are emanating

from Gwalior substation in Western Region. This necessitates a high level of reliability of

765/400/220 kV Gwalior substation. All the equipment and protective systems at this

substation needs to be checked thoroughly to avoid any mis-operations which could be

catastrophic under heavy power flow scenario. The TTC between WR and NR would

undergo a sharp downward revision whenever the transmission lines involved are under

planned or forced outage.

WRPC and NRPC are requested to approve the modifications in SPS and have the same

implemented and tested. Only after confirmation of the same, it is possible for NLDC/RLDCs

to enhance the TTC between WR and NR suitably.

4

A. Modifications Suggested in the SPS settings:

Case Triggering criteria for SPS (implemented) Proposed revision in SPS Remarks

Case-1 Reduction of import by NR on 765 kV Agra-

Gwalior Ckt-1 & II by more than 1000 MW but

less than 1500 MW.

Action:

Shed loads in Group C and D in the NR

To be blocked

Case-2 Reduction of import by NR on 765 kV Agra-

Gwalior Ckt-1 & II by more than or equal to

1500 MW

Action-1:

Shed loads in Group C, D, E and F.

Action-2:

Automatically back down 500 MW generation in

WR in the shortest possible time at Korba,

Vindhyachal, CGPL Mundra Stations.

Reduction of import by NR on 765 kV Agra-

Gwalior Ckt-1 & II by more than or equal to

3000 MW. (The sum of flows on these

circuits would be continuously compared with

the sum of flows two (2) seconds earlier and

the SPS would activate if the difference

crosses 3000 MW).

Action-1:

Shed loads in Group C, D, E and F.

Additional loads to tune of 500-1000 MW

needs to be identified.

This Situation is

anticipated when 765kV

Gwalior-Agra ckt-1 & 2

trip with combined

antecedent flow exceeding

3000 MW.

5

Case Triggering criteria for SPS (implemented) Proposed revision in SPS Remarks

Action 3:

Trip 220KV Gwalior-Malanpur D/C in case of

sensing of tripping of both 765KV Gwalior-Agra

ckt 1 & 2.

Action-2:

Automatically back down 1000 MW

generation in WR in the shortest possible time

at Vindhyachal, Sasan, CGPL Mundra.

Action-3:

To be blocked

In addition to this, tripping of 220KV

Gwalior-Mahalgaon D/C in case of

sensing of tripping of 765 kV Bina –

Gwalior may also be blocked.

With the commissioning

of 765 kV Gwalior –

Phagi D/C in parallel with

765 kV Gwalior-Agra

D/C, inter tripping of

parallel 220 kV lines is

not needed now.

6

Case Triggering criteria for SPS (implemented) Proposed revision in SPS Remarks

Case-3 When both ckts are in service and total steady

state flow on 765 kV Gwalior to Agra is more

than 2800 MW for a period of 10 seconds

Or

When only one ckt is in service and flow on 765

kV Gwalior to Agra is more than 1800 MW for a

period of 5 seconds

Or

Steady state voltage at 400kV Agra less than 380

kV & more than 50kV for a period of 10 seconds

(direction of power flows is WR to NR)

Action-1:

Shed loads in Group C, D.

When both ckts are in service and total steady

state flow on 765 kV Gwalior to Agra is more

than 4000 MW for a period of 10 seconds

Or

When only one ckt is in service and flow on

765 kV Gwalior to Agra is more than 3000

MW for a period of 5 seconds

Or

Steady state voltage at 400kV Agra less than

380 kV & more than 50kV for a period of 10

seconds (direction of power flows is WR to

NR)

Action-1:

Shed loads in Group C, D.

This situation will prevail

if both Gwalior-Phagi

lines go out or when both

Mundra-Mohindergarh

HVDC poles go out.

Or

This situation will prevail

if Gwalior-Agra one

circuit goes out

7