f-3, midc area, andheri (east), mumbai - 400 093 durbaaya … · 2008. 4. 30. · mpptcl...

Baart sarkar Government of India kond`Iya ivaVut p`aiQakrNa

Central Electricity Authority piScama xao~Iya ivaVut saimait

Western Regional Power Committee ef -3, emaAayaDIsaI xao~, AMQaorI (pUva-), mauMba[- - 400 093

F-3, MIDC Area, Andheri (East), Mumbai - 400 093

Aa[- esa Aao : 9001-2000 ISO : 9001-2000

dUrBaaYa Phone: 022- 28221681; 28200194/195/196; fO@sa Fax : 022 – 28370193 Website : www.wrpc.nic.in E-mail : [email protected]

¬¸¿‰¡¸¸: £®¸μ¸ / 100 œ¸ú¬¸ú‡Ÿ¸ / 2008 / œ¸®¸½¹¨¸¬¸¢Ÿ¸¢÷¸- 3794 ¹™›¸¸¿ˆÅ :25/04/2008 No. :Prot./ 100 PCM / 2008 / WRPC-3794 Date: 25/04/2008

¬¸½¨¸¸ Ÿ¸½¿ /To, ¹¨¸«¸¡¸:- ¢™›¸¸¿ˆÅ 07 ‡¨¸¿ 08 ‚œÏ¾¥¸ 2008 kao Ÿ¸.œÏ. œ¸¸¨¸£ ’ï¸¿¬¸¢Ÿ¸©¸›¸ ˆÅŸœ¸›¸ú ¢¥¸¢Ÿ¸’½”, ¸¤¸¥¸œ¸º£ Aayaaoijat

kI ga[- £®¸μ¸ ¬¸¹Ÿ¸¹÷¸ ˆÅú 100 ¨¸ì ¸¾“ˆÅ ˆÅ¸ ˆÅ¸¡¸Ä¨¸¼î¸— Sub :- Minutes of 100th Protection Committee Meeting held on 07th & 08th April 2008 at M.P.

Power Transmission Company Ltd., Jabalpur. Ÿ¸−¸½™¡¸ / Sir,

ƒ¬¸ œ¸°¸ ˆ½Å ¬¸¸˜¸ ¢™›¸¸¿ˆÅ 07 ‡¨¸¿ 08 ‚œÏ¾¥¸ 2008 kao ¸¤¸¥¸œ¸º£ Ÿ¸½¿ ‚¸¡¸¸½¢¸÷¸ ˆÅú Š¸ƒÄ œ¸¢©¸Ÿ¸ ®¸½°¸ú¡¸ ¢¨¸Ô¸º÷¸ ¬¸¢Ÿ¸¢÷¸, Ÿ¸º¿¤¸ƒÄ ˆÅú £®¸μ¸ ¬¸¹Ÿ¸¹÷¸ ˆÅú 100 ¨¸ì ¸¾“ˆÅ ˆÅa ˆÅ¸¡¸Ä¨¸¼î¸ ‚¸œ¸ˆÅú ¬¸»¸›¸¸ ‡¨¸¿ ‚¸¨¸©¡¸ˆÅ ˆÅ¸£Ä¨¸¸ƒÄ í½÷¸º ¬¸¿¥¸Š›¸ í¾ —

Please find enclosed herewith the minutes of 100th Protection Committee Meeting of Western Regional Power Committee, Mumbai held on 07th & 08th April 2008 at Jabalpur for your information and necessary action.

¤¸¾“ˆÅ ˆÅ¸ ˆÅ¸¡¸Ä¨¸¼î¸ œ¸®¸½¢¨¸ ¬¸¢Ÿ¸¢÷¸ ˆÅú ¨¸½¤¸¬¸¸ƒ’ www.wrpc.nic.in œ¸£ ž¸ú „œ¸¥¸¤š¸ í¾ — Minutes are also available at WRP Committee website www.wrpc.nic.in

š¸›¡¸¨¸¸™ /Thanking you

ž¸¨¸™ú¡¸/Yours faithfully,

(‡¬¸.”ú.’¸ˆÅ¬¸¸¿”½/S.D. Taksande) ‚š¸ú. ‚¹ž¸.(£.)/Suptdg. Engr.(P.) ¬¸¿¥¸Š›¸ /Encl. :- „œ¸£¸½Æ÷¸¸›¸º¬¸¸£ /As above

Minutes of 100th WRPC PCM

MINUTES OF THE 100th PROTECTION COMMITTEE MEETING

The 100th Protection Committee Meeting of WRPC was held on 07th & 08th April

2008 at MPPTCL, Jabalpur. The list of participants is placed at Annex -I.

Shri R.K.Verma, CMD, Madhya Pradesh Power Transmission Company

welcomed the members & participants to 100th Protection Committee Meeting

and thanked them for attending this meeting from far away places in the city of

Jabalpur. He stated that there are many sub committees in WRPC, but Protection

Committee is the only forum where detailed technical discussions are held and

full co-ordination without difference of opinion is achieved in solving the

problems related to protection system in the WR grid. He stated that in MPPTCL

all old relays in the important sub-stations are being replaced by numerical relays

and advised other constituents to follow. He thanked WRPC for giving MPPTCL

an opportunity to host this 100th WRPC Protection Committee Meeting. He hoped

that the discussions during this Protection Committee Meeting would give fruitful

results and the Protection Engineers of the constituents of WRPC would share

their experiences and implement the decisions/recommendations of the Protection

Committee to improve the performance of the Western Grid.

Shri P.Patel, Member Secretary, WRPC, welcomed all the members and invitees on

behalf of WRPC to the 100th Protection committee meeting. He thanked MPPTCL for

having consented to host this meeting at Jabalpur and also for the excellent arrangements

made for the meeting and comfortable stay of participants. He said that Shri R.K.Verma,

CMD, MPPTCL was a prominent personality in the field of protection system and

thanked him for gracing the occasion in spite of his busy schedule. He stated that system

has become more stable and appreciated that the number of occurrences is decreasing due

to efforts of protection engineers in the region. He then requested Shri S. D.Taksande,

Superintending Engineer (Protection), WRPC to take up Agenda items for discussion.

Shri S. D.Taksande, Superintending Engineer (Protection), WRPC, expressed

special thanks to Shri D. Godbole, Executive Director (T&C) and his team of


dedicated engineers of Shri R.K. Mehta, Superintending Engineer (T&C) and Shri

K.K. Agrawal, Addl. Superintending Engineer (T&C) for the excellent

arrangements made for the meeting and comfortable stay of the participants..

Thereafter the agenda was taken up for discussion.

Item No.1: Confirmation of Minutes of 99th Protection Committee Meeting.

Superintending Engineer (Protection), WRPC, stated that minutes of 99th Protection

Committee Meeting of WRPC held on 24th & 25th January 2008 at WRPC,

Mumbai, were circulated vide WRPC letter no. Prot./99-PCM/2007-

08/WRPC/13666 dated 12th February 2008.

Comments received from NPCIL vide their email dated 3rd March 2008 for

observations recorded under item 2.09 of minutes of 99th P.C.M. were discussed.

MSETCL informed that Zone II settings on 220kV Taps-Boisar and 220kV

Boisar(PGCIL)-Boisar(MSETCL) is 400ms, instead of 300ms, as informed earlier.

As such the lines “It was observed by Committee that general practice of

adopting Zone-II timing of 400ms may be considered as MSETCL has adopted

300ms as per their practice on TAPS – Boisar line.” should now be read as “It

was suggested by the Committee that in order to achieve time discrimination,

so that 220kV Taps - Boisar feeder trips later to 220kV Boisar- Boisar feeder,

zone II setting on 220kV Boisar-Boisar line is to be reduced to 300ms,

retaining zone II timing on 220kV Boisar-Tarapur as 400ms at Boisar,

MSETCL end”.

The minutes for 99th Protection Committee Meeting were confirmed with above change in Zone-2 timing.

Item No.2: System disturbances

2.01: System disturbance at 400 kV Nagda S/S in MPPTCL system on 01-10-2007

MPPTCL representative informed that on 01.10.2007 at 15:35Hrs, at 400kV Nagda

S/S, all the three 400/220kV, 315MVA ICTs tripped on operation of back up E/F

protection and all 400kV feeders tripped on Over Voltage due to failure of B-phase

pole of 220kV Interconnector-I feeder, CGL make SF-6 breaker having Sr. No.


2962-C manufactured in 1989 and commissioned at Nagda on 06.06.1992. The

breaker was in OFF condition and was charged from bus side only. 220kV Nagda-

Ujjain and 220kV Nagda- Ratlam feeders tripped from remote ends on Zone-II

indication causing total supply failure at 400kV Nagda S/S. Prior to this on 30-09-

07 at 19:05hrs, while hand tripping the 220kV Nagda Int.-I, during the system

disturbance at 400kV Nagda S/S, low SF6 pressure was observed, hence the

breaker was kept OFF, however supply was available at both ends of the CB, since

it was charged from 220kV Nagda S/S, and isolators were ON. On 01-10-07 at

15:25hrs. Nagda Int.-I was hand tripped from 220kV Nagda S/S and the line

isolator was opened, for isolating faulty CB. At 15:35hrs B phase pole of the CB

got burst.

Supply at 400kV Nagda S/S was restored at 16:08Hrs.

Committee observed that,

(i) Had the correct procedure of isolating the breaker by opening the isolators, would

have been followed, B-Phase pole of SF6 breaker would not have blasted as it can

withstand complete loss of pressure as well.

(ii) Had there been bus bar protection on 220kV bus, only 220kV lines connected to that

bus would have tripped and there would have been no 400kV lines tripping.

2.02: System disturbance at 400/220 kV Chorania S/S in GETCO system on 09-10-2007

GETCO representative informed that on 09.10.2007 at 22:22 Hrs, one of the twin

conductors of B phase jumper (twin ASCR moose conductors) between isolator 29

A of ICT-1 & 220kV Bus A snapped from the top and fell on ground causing bus

fault. This resulted in tripping of all 220kV feeders at 400/220kV Chorania S/S

from opposite end. The bus bar protection did not operate as CT supervision feature

operated blocking the scheme. GETCO representative informed that a very high

resistive arcing between conductor and ground have taken place while the

conductor was snapping before touching the ground. This might have resulted in

operation of CT supervision relay, due to low fault current, thus blocking the Bus

Bar protection scheme and resulting in tripping of all the feeders from remote end.

The timer setting of the CT supervision relay was set at 500 ms.


All tripped feeders and ICT-2 were charged between 23:39Hrs of 09.10.2007 and

00:20Hrs of 10.10.2007.

(i) Committee observed that RADSS bus bar protection scheme having IDMT

characteristics did not operate, as timer was set to 500 ms, and due to

resistive nature of fault current was low and thus CT supervision relay

operated blocking the bus bar protection. GETCO informed that timer was

now set to 5 seconds instead of 500ms so as to accommodate low current

faults.

(ii) Committee observed that had reverse zone been used to trip bus coupler, one

bus would have been saved.

(iii) Committee suggested for spacers on conductor as per normal practice so that

conductors would not have touched ground consequent upon snapping.

GETCO agreed to do the needful.

2.03: System disturbance at 220 kV Eklahare S/S in MSETCL system on 11-10-2007

MSETCL representative informed that on 11.10.2007 heavy oil leakage was

observed on R-phase pole of 132kV Sinnar feeder BHEL make MOCB (HLD

145/1250A). Hence, it was decided to transfer this load on TBC and to attend this

own CB problem. The bus transfer operations were done. The TBC CB was

closed .At 11:56Hrs, during hand tripping of own breaker, to transfer the load to

TBC, R phase pole partially opened and got stuck up. The interrupting chamber of

this pole was completely empty due to draining of oil and hence heavy arc was

established across the contacts. O/C and E/F relay was made non-directional by

bypassing its directional feature, as the 132kV Sinnar feeder was feeding radial

load. This led to E/F condition and resulted in LBB operation, resulting in

tripping of all the elements connected to 132kV Main Bus of 220kV Eklahare

GCR S/S.

All tripped feeders and ICT-1 & 2 were charged between 12:23Hrs and 16:48Hrs

on 11.10.2007. 132kV Sinnar feeder was charged through TBC. The faulty R phase


pole of the own CB was replaced on 14.10.2007.

Committee observed that tripping of Sinnar feeder on E/F was OK, since relay

was made non-directional, due to radial load connected to it. Also unbalance

current circulation in breaker caused fault like condition and thus operation

of LBB was in order. Committee suggested that the LBB configuration should

be converted from existing 2 O/C + 1 E/F to 3 O/C and the directional feature

of 132kV Sinnar feeder should be restored.

2.04: System disturbance at 400 kV Bina S/S of PowerGrid on 13-10-2007

PowerGrid representative informed that on 13.10.2007 at 15:39 Hrs, ABB

make B phase CT of the main bay blasted within 15 minutes while 400kV Bina –

Nagda Ckt-1 was test charged resulting in tripping of this line on Earth Fault and

operation of Bus Bar Protection of 400kV Bus –II at Bina S/S.

During this occurrence, 400kV Bina – Gwalior tripped from remote end and

400kV Bina (PGCIL) – Bina (MPPTCL) ckt-1 tripped from local end, which

appears to be mal-operation. Apart from this, all other lines connected to Bina S/S

remained in service,

Reason for tripping of 400kV Bina – Gwalior line, it was found that in the Bay

Module of Bus-bar protection (ABB make REB-500) one contact, which was

configured for AELO purpose, was mistakenly got interchanged with the contact

configured for DT send. This problem arose because this relay is having built-in

LBB function also and some contacts are used for DT send in case of operation of

LBB protection. But the DT send is not required in case of operation of Bus bar

protection. The interchanging has been corrected.

The operation of Bus bar protection of Bus-II should have given trip command

only to the Tie CB of 400kV Bina (PGCIL) – Bina (MPPTCL) ckt-1 (because of

incomlete dia). As both Tie & Main CB panels are adjacent inside the same kiosk,

due to some wiring mistake, the same command also got extended Main CB,

resulting in tripping of the feeder. The same has been rectified.


Committee observed that 400kV Bina is a new sub-station having automation

commissioned in 2007. Tripping of 400kV Nagda –Bina line on operation of

Main 1 & 2 and 400kV Bus-II on operation of Bus-bar protection is a correct

operation and tripping of 400kV Gwalior & Bina (MPPTCL) lines was

attributed to wrong wiring while commissioning.

POWERGRID WRTS- II representative informed the committee that the

whole lot of CTs have been replaced by M/s ABB and wiring problem during

commissioning has been rectified by the supplier.

2.05: System disturbance at 400/220 kV Parli S/S in MSETCL system on 09-11-2007

MSETCL representative informed that on 09.11.2007 at 17:25Hrs, Unit # 5 at

new TPS Parli generating around 180MW power tripped on boiler tube leakage

protection. Subsequently at 18:23Hrs Unit # 6 generating around 197MW power

tripped on flame fail protection. The 2x315MVA ICT loading started increasing

after first tripping of Unit # 5 and aggravated the problem after tripping of Unit #

6 resulting in tripping of both ICTs on backup protection at 18:30Hrs.

Committee observed that tripping of unit 5 and 6 are independent tripping

and had there been load trimming scheme, ICT’s could have been saved

from tripping.

MSETCL reported that, at Girwali 400kV S/S, a load - trimming scheme

using ER make DCD (Argus) Relay has been commissioned to trim the load

after the said occurance.

2.06: System disturbance at 400/220 kV Padghe S/S in MSETCL system on 17-12-2007

MSETCL representative informed that on 17.12.2007, in order to carryout

retrofitting work of “Trip Circuit Supervision Relay” of 400kV Bableshwar ckt.-

II, line was being taken on TBC. The ‘Trip circuit Faulty” indications appeared on

TBC control panels. It was observed that there was sudden drain out of oil from

B-pole of TBC CB of M/S BHEL make. The 400kV TBC CB went in lockout.


The 400kV Bableshwar –II line CB was hand tripped from remote end as per

SLDC instructions. The TBC breaker received D/T from Bableshwar end. Due to

L/O conditions of TBC, two poles (R&Y) were opened. However “B” phase pole

did not trip and remained ‘ON’ from Padghe end. The 400kV Bableshwar 2 ‘C

bus isolator’ was attempted to open under Unloaded Long lines i.e. breaking of

Capacitive Current of long unloaded line. Heavy arcing was observed by the

operating personnel and resulted in incomplete operation.

During this process at 13:52Hrs, both 400kV main bus I & II tripped due to

operation of 400kV bus bar protection resulting into tripping of all the equipments

connected to 400kV main bus I & II at 400kV Padghe S/S. HVDC pole I & II

tripped due to loss of 400kV AC supply at 400kV Padghe S/S.

All tripped feeders, HVDC and ICTs were charged between 14:10Hrs and 20.18Hrs

of 17.12.2007.

Committee observed that opening of remote end breaker of Bableshwar feeder

when TBC breaker was in lock out condition at Padghe, was incorrect

operation.

Had the own breaker taken in parallel with TBC breaker then opening from

remote end is correct.

Opening of long unloaded line through isolator was also not correct and

should not be done, as it may lead to accidents. Committee suggested for

observing standard operating practices while transferring loads. Isolator

opening by remote through motor is recommended, instead of manual

opening.

2.07: System disturbance at 220 kV Khaparhkeda TPS S/S in MSETCL system on 18-12-07

MSETCL representative informed that on 18.12.2007 at 02:50Hrs, all breakers

including bus coupler connected to 220kV Bus-II, except that of GT # 1 and 220kV

Koradi feeder, tripped at 220kV Khaperkheda S/S due to operation of LBB

protection while withdrawing the Generator unit No.1 connected to the same bus at


PCR end. There was no tripping at any of the remote end S/Ss. Flame failure

protection, MTR (86) & LBB reportedly operated for GT # 1 bay at PCR end at

Khaperkheda TPS. The Trip Circuit Faulty indication remained persistent at GCR

end. On investigation both the trip coils (Trip coil 1 & 2) of the GT # 1 breaker

(BHEL make Gang operated MOCB; Type: HLR245/2502E;Yr of mfr: 1988; Sr

No. 310313) were found burnt, indicating stuck condition of the breaker.

Normalcy of supply was restored by charging of GT # 4 at 10:13Hrs on the same

date, while Gen Unit # 1 kept under outage by PCR for annual maintenance.

Committee observed that operation of LBB protection of GT 1 bay on

initiation of MTR (Master Trip Relay) due to trip coil burning and consequent

selective tripping of breakers connected to 220kV main Bus-II was in order.

MSETCL representative informed that trip +ve wire from the terminal in

relay panel of Koradi bay was disconnected resulting in non tripping of

Koradi feeder, same has been rectified.

BHEL breaker of GT#1 was replaced by CGL breaker.

ITEM NO. 3: Tripping of lines / ICTs:

The incidences of tripping of lines and ICTs during the period 01-10-2007 to31-12-

2007 were discussed during the meeting.

Observations of the committee are enclosed at Annex –3.

ITEM NO. 4: Protection related recommendations on Grid Disturbances in Western

Regional Grid on 25.2.2007 at 1634 hours and 28.2.2007 at 13:11 hours:

Protection related recommendations of the Enquiry Committee on Grid Disturbances

in Western Regional Grid on 25.2.2007 at 1634 hours and 28.2.2007 at 13:11 hours

were reviewed for implementation during the meeting and the present status

regarding implementation of recommendations is placed at Annexure-4.


ITEM NO.5: Follow up points:

5.01: Procurement of new Busbar protection scheme at 400 KV Nagda MPPTCL S/S:

PowerGrid have intimated that 400kV Nagda S/S of MPPTCL is now inter-

connected strongly in the grid with the commissioning of 400kV Bina D/C lines

since October 2007 and 400kV Dehgam D/C lines since January 2008. PowerGrid

has requested for early commissioning of Bus Bar Protection Scheme at 400kV

Nagda S/S in view of importance of the 400kV Nagda S/S in the WR grid.

MPPTCL representative informed that Bus Bar protection panel in

respect of 220kV have arrived at site and 400kV panel consisting of

low impedance REB 670 ABB make busbar protection scheme is likely

to arrive shortly at Nagda.

5.02: Implementation of Revised Mumbai Islanding Scheme:

Revised Mumbai Islanding Scheme, as recommended by the Enquiry Committee

on Grid Disturbance of 25th & 28th February, 2007, was commissioned, except

reverse power condition at Boisar. During 99th PCM, it was informed by REL

representative that summation CTs and reverse power relays at 220kV Boisar

MSETCL S/S would be provided within two months time.

REL representative informed that they would be receiving summation CTs by

middle of May 2008. Summation CTs and reverse power relay at 47.9Hz shall be

commissioned at 220kV MSETCL Boisar S/S during May 2008.

REL representative further informed that they have additionally installed

reverse power relays at 47.8Hz in their Versova and Dahanu stations as back up.


ITEM NO. 6: Other grid points:

6.01: Non auto-reclosure of PowerGrid lines connected at 400kV Bhilai S/S

of CSEB

POWERGRID representative informed that they have recently changed four nos.

old protection to numerical relays in POWERGRID bays at 400kV Bhilai S/S of

CSEB. This was done to facilitate successful auto-reclosure of lines and speedy

clearance of the faults. In recent tripping of 400kV Korba – Bhilai Ckt.-1 on

05.01.2008, it was observed that the line did not auto-reclose from Bhilai end due

to auto-reclosure switch being put in non-auto mode at CSEB. Even after

discussions with CSEB, the switch has still not been put in auto-mode.

CSEB representative has intimated that all the auto re-close switches of main

Breakers of lines have been kept on single- phase auto re-closing mode as per the

request of POWERGRID, but due to low pressure persisting, Auto reclosure is

not taking place.

CSEB representative informed that at 400kV Bhilai S/S, there exists centralized

air pressure system for the breakers where air pressure remains below 31Kg..

POWERGRID and CSEB are going to replace all the 400kV ABB make ABCBs

by the year 2009

6.02: Configuration of PLCC protection in 220kV lines

POWERGRID intimated that during system occurrence at Boisar S/S on

22.09.2007, due to failure of CT jumper of 220kV Boisar(PGCIL) – Boisar

(MSETCL) line, bus bar protection operated at Boisar(PGCIL) S/S. It was

observed that all the protections operated correctly at Boisar, but fault could not

be cleared due to non-opening of breaker of remote end, as the PLCC protection

was not connected for direct trip command to the remote breaker, which has

resulted into tripping of all the lines on Zone-2 timing at Boisar/nearby S/Ss of

MSETCL. Subsequently, one code of PLCC was configured for direct trip

command (Busbar, LBB and Hand Trip), same needs to be done for two other


feeders Nalasopara and Padghe at PowerGrid, Boisar S/S. Matter has been taken

up with MSETCL for corrective action.

Further, to avoid such tripping at other stations also where connectivity at

PowerGrid station with 220kV system is there, similar arrangement are to be

made at PowerGrid station, so that repetition of similar instance of dated

22.09.2007 at Boisar S/S can be avoided.

MSETCL representative informed that 220kV Boisar – Boisar feeder D.T.

has been commissioned. As far as configuration of one code of PLCC for

direct trip command for other two feeders 220kV Boisar – Nalasopara and

220kV Boisar – Padghe feeders are concerned, only one channel is available

and therefore proposal for second channel has been sent to their Head Office.

CSEB representative informed that they have done the needful.

MPPTCL representative informed that only one direct trip code is

commissioned in respect of 220kV Rajgarh – Rajgarh and 220kV Rajgarh –

Pithampura feeders and therefore proposal for additional permissive trip

code to incorporate in carrier trip will be sent soon.

GETCO representative informed that D.T. is not available for 220kV Bhilad

– Vapi feeders and the same will be provided by May 2008 end.

6.03:Non availability of Event Logger and GPS clock at PowerGrid connected

400kV Sub stations

PowerGrid WRTS-II have intimated that no Event Logger & GPS is available at

important 400kV Sub Stations at Nagda & Indore of MPPTCL and Dhule of

MSETCL connected to PowerGrid WRTS-II system which may hamper proper

analysis in the event of any grid disturbance and the available Disturbance

Recorders are not time synchronized. This is a recommendation of many Enquiry

Committees on grid disturbances in WR grid and is regularly monitored in monthly


WRPC OCCM.

MPPTCL representative informed that Event Logger and GPS clock at Nagda

and Indore 400kV S/Ss have been included in ERP (Enterprising Resource

Planning) Scheme. Event Loggers are embedded in numerical relays being

provided at Nagda S/S.

MSETCL representative informed that provision of Event Logger and GPS

clock at 400kV Dhule S/S has been included in SMS Scheme and will be

implemented in 5 to 6 months time.

GETCO representative informed that Event Logger and GPS clock are

available at their 400kV S/Ss.

CSEB representative has informed that CSEB is going to acquire GPS clock

system in 400kV Khedamara, Bhilai S/S very soon.

6.04:Frequent tripping of 220kV Auraiyya – Malanpur lines

220 kV Auraiyya – Malanpur lines are important Inter – Regional link between

NR and WR connecting Auraiyya GPS of NTPC in NR to 220kV Malanpur S/S of

MPPTCL in WR. NRPC informed that 220 kV Auraiyya – Malanpur ckt # 2

tripped twice in December 2007 and also it tripped on 31.01.08 & 02.02.08 i.e.

within a span of two days which is not desirable. Moreover frequent tripping of this

particular line is unsafe for Auraiyya GPS of NTPC as well as for both the grids of

NR and WR. Also due to non-availability of protection coupler facility, protection

inter tripping through carrier is not possible under present condition.

MPPTCL representative informed that patrolling was carried out on 220kV

Auraiyya – Malanpur line on its tripping in the month of December 2007 and

January 2008 and nothing abnormal was noticed. Regarding provision of

protection coupler on these lines, MPPTCL informed that the same will be


provided within three months period.

6.05: Revision of settings of df/dt UFLS relays in WR grid

WRP Committee in its 6th meeting held on 11th January 2008 at Port Blair

discussed the revision of settings of df/dt UFLS relays in WR under item No. 9 and

advised WRLDC to discuss the matter with other RLDCs in the integrated grid

namely NRLDC & ERLDC and come out with jointly agreed df/dt settings for

approval of the WRP Committee. The jointly agreed scheme by RLDCs, as

received from WRLDC was circulated to participants during the meeting for

information of the Committee.

Member Secretary, WRPC informed the committee that this revision of

settings of df/dt UFLS relays in WR grid will also be discussed in other WRPC

forums like OCCM before approval of WRP Committee and upon approval

from WRPC, the same will again be discussed in this forum for

implementation.

ITEM NO. 7: Any other issues:

7.01: System disturbance at 400 kV Bhilai S/S in MPPTCL system on 04-10-2007

(The item no.3.09 and 3.18 of agenda has been shifted to major occurrence, as there were

multiple trippings)

MPPTCL representative informed that on 04.10.2007 at 11:47Hrs, at 400kV Bhilai

S/S, 400kV Korba (West) – Bhilai feeder tripped on transient S phase to earth fault

in zone-I at Bhilai end but the feeder did not trip at Korba (West) end due to local

problem i.e. burnt of terminal block in a fire incidence at Korba(West) end. As the

fault was being fed from Korba(West ) S/S through 400kV Korba(West) – Korba

(NTPC) feeder and 210MW generating Unit # 4 connected to bus through Bus

Coupler. 400kV Korba(West) – Korba (NTPC) feeder tripped at Korba (NTPC) end

in zone-II however it did not trip at Korba (West) end due to local problem as

mentioned above. The Bus Coupler at 400kV Korba(West) S/S tripped on over

current resulting in tripping of 210MW generating Unit # 4 on load throw off.


System was normalized immediately by restoring 400kV Korba(West) – Korba

(NTPC) feeder at 13:27Hrs on the same day.

Committee felt that as bus coupler tripped on O/C, isolating the two buses, the

spread of occurrence had been minimized.

7.02: Over Voltage stage-II protection of 400kV lines

During 98th and 99th PCMs, representative of MSETCL, Nashik had proposed for

some delay to the tune of 50msec to be given to O/V stage-II setting at Bableshwar

having voltage setting of 150% without any intentional delay. Committee had

agreed to MSETCL proposal of having 50 ms delay for O/V stage-II protection of

400kV lines and pointed out that as per CBIP guidelines, 100 ms delay for O/V

stage-II protection is permitted for setting at 150%. Committee re-confirmed the

proposed delay of 50 ms for O/V stage-II protection set at 150%.

Superintending Engineer (T&C), MSETCL, Nashik informed that they have

received an instruction from their Executive Director (Operation) to implement in

letter and spirit the recommendation regarding O/V stage-II setting of 150% with

100ms delay as per CBIP manual no. 274. In view of this, Superintending Engineer

(T&C), MSETCL, Nashik requested WRPC PCM forum for permission to adopt

100ms delay instead of 50ms already recommended by WRPC.

Committee discussed the matter and was of the opinion that the proposed

50ms time delay by MSETCL was agreed with the intention of minimizing the

O/V stress on equipments. As recommendations of CBIP (no.274) on O/V are

being referred by protection engineer all over India and are of standard

nature, therefore, MSETCL may adopt 100ms delay in O/V stage-II setting

not withstanding 50ms recommended by WRPC in earlier meetings.

7.03: Paper presentation by TPC representative

A paper on ”Dissolved Gas Analysis (DGA) of Current Transformer (CT) oil – A


reliable tool to identify manufacturing defects” by Shri A.K. Datta, Shri S.C. Singh,

Shri S.K. Mishra and Shri S. Suresh of Power Grid Corporation of India Limited

was presented in Doble Conferrence at Baroda in 2006. The said paper was read by

Shri Muralikrishna, representative of TPC, for the benefit of the participants. This

paper is made available on WRPC website for further reference.

ITEM NO. 8: Date and Venue of the next meeting.

It was decided that the next meeting (101st) will be hosted by NTPC during June

2008, wherein system disturbances for the period 01-01-2008 to 31-03-2008 will be

discussed. Exact date and venue will be communicated separately.


ANNEX-I

LIST OF PARTICIPANTS

100th Protection Committee Meeting held on 7th & 8th April, 2008 at MPPTCL, Jabalpur

MSETCL (Maharashtra State Electricity Transmission Company Limited) Shri B.T. Mahale Superintending Engineer (TCC), Nashik Shri S.A. Jaolikar Superintending Engineer (TCC), Vashi Shri A.D. Wankhede Superintending Engineer (TCC), Pune Shri P.S. Ingle Dy. Executive Engineer (TCC), Pune Shri J.G. Nandapurkar Dy. Executive Engineer (TCC), Nagpur Shri D.Y. Chavan Dy. Executive Engineer (TCC), Nashik Shri D.P. Nandanwar Dy. Executive Engineer (TCC), Vashi MAHAGENCO (Maharashtra State Power Generation Company Limited) Shri A.K. Patil Superintending Engineer (TIC), Nagpur MPPTCL (Madhya Pradesh Power Transmission Corporation Limited) Shri D.Godbole Executive Director (T&C), Jabalpur Shri R.K. Mehta Superintending Engineer (T&C), Jabalpur Shri K.K. Agrawal Addl. Superintending Engineer (T&C), Jabalpur Shri A. K. Shrivastava Executive Engineer (T&C), Indore MPPGCL (Madhya Pradesh Power Generation Corporation Limited) Shri J.S. Grover Addl. Chief Engineer (TH.-D), Jabalpur Shri O.P. Verma Assistant Engineer, STPS, Sarni CSEB (Chhatisgarh State Electricity Board) Shri Anil Dhar Superintending Engineer, MRT, Raipur Shri G.P. Rai Executive Engineer, Korba (West) Shri N.K. Parmar Executive Engineer, Bhilai


GETCO (Gujarat Energy Transmission Corporation Limited) Shri B.R. Panchal Addl. Chief Engineer (Testing), Baroda GSECL (Gujarat State Electricity Corporation Limited) Shri U.D. Adhvaryu Superintending Engineer (Testing), Baroda NTPC (National Thermal Power Corporation) Shri Jitendra Tiwari Dy. General Manager(EM), VSTPS, Vindhyachal NPCIL (Nuclear Power Corporation of India Limited) Shri Nishant Dhimole SO/D, TAPS-3 & 4, Tarapur Shri D.V. Kodge SO/D, TAPS-1 & 2, Tarapur Shri Subhas Lumbani SO/D, KAPS, Kakrapar PGCIL (Power Grid Corporation of India Limited) Smt. Sachala Mishra Manager, WRLDC, Mumbai Shri Anand Dubey Manager, WRTS-II, Vadodara Shri S. Suresh Dy. Manager, WRTS-I, Nagpur TPC (Tata Power Company) Shri T. Muralikrishna Sr. Manager, Trombay, Mumbai REL (Reliance Energy Limited) Shri D.M. Derashale Addl. Manager (T&P), Mumbai Shri Sandip S. Vaidya Addl. Manager, Dahanu TPS, Dahanu WRPC (Western Regional Power Committee) Shri P. Patel Member Secretary Shri S. D. Taksande Superintending Engineer (P) Shri B. R. Joshi Executive Engineer (P)


ANNEXURE-3

TRIPPINGS OF LINES / ICTS

Sl. No.

NAME OF S/S

DATE OUT AT

NAME OF THE LINE/ICT

SYSTEM / Provision of A/R (Yes/No)

DATE/ CHARGED AT

REASON

3.01

400kV Asoj

01.10.07 11:55

400kV Asoj – Indore # 2

POWERGRID (Y)

12:05 A/T on transient Y-ph to E/F and A/R operated successfully at Asoj end.

3.02 400kV Indore

01.10.07 20:25

400kV Indore- Asoj # 2

POWERGRID (Y)

20:33 A/T due to Main Bus B-ph Ten-sion String fell near Asoj ckt-1

3.03 400kV Kasor

02.10.07 00:55

400kV Kasor – SSP

GETCO (Y)

07:25 A/T due to O/V.

3.04 400kV Kasor

03.10.07 03:30

400kV Kasor – GPEC

GETCO (Y)

03:30 A/T on transient Y-ph to E/F and successfully A/R at both ends.

3.05 400kV Chandra-pur

03.10.07 09:15

400kV C’pur – Parli # 1

MSETCL (Y)

04.10.07 04:07

A/T due to R-ph conductor snapping alongwith insulator string at Loc. No. 358

3.06 400kV Kasor

04.10.07 03:58

400kV Kasor – SSP

GETCO (Y)

07:23 A/T due to O/V.

3.07 ---deleted---- 3.08 400kV

Itarsi 05.10.07 02:11

400kV Itarsi- Indore # 1

POWERGRID (Y)

02:50 A/T on transient B-N fault. A/R successful at Itarsi end only.

3.09 400kV Asoj

05.10.07 03:36


POWERGRID (Y)

06.10.07 00:25

A/T due to mal-operation of reverse reach.

3.10 400kV Bhadravati

05.10.07 15:25

400kV B’vati –C’drapur #3

POWERGRID (Y)

15:25 A/T on transient R-N fault and successfully A/R at both ends.

3.11 400kV Indore

05.10.07 23:15

400kV Indore Asoj # 1

POWERGRID (Y)

06.10.07 00:25

A/T (reactor Back up impedence relay YTG-31) due to LA failure on 220kV Asoj – Jambua line at Asoj end.

3.12 400kV Korba

08.10.07 11:35

400kV V’chal- Korba # 2

POWERGRID (Y)

10.10.07 17:10

A/T due to DC earth leakage at Vindhyachal end.

3.13 400kV Asoj

10.10.07 00:48

400kV Asoj – Amreli

GETCO (Y)

01:00 A/T on transient B-ph to E/F and A/R operated successfully at Amreli end. Low air pressure at Asoj end.

3.14 400kV Asoj

10.10.07 05:45

400kV Asoj – Chorania

GETCO (Y)

06:05 A/T on transient Y-ph to E/F and A/R operated successfully at Asoj end. Low air pressure at Chorania end.

3.15 220kV TAPS

12.10.07 14:42

220kV TAPS- Bhilad

GETCO (Y)

15:25 A/T from both ends on transient C-ph to E/F.

3.16 400kV Bhopal

15.10.07 15:10

400kV Bhopal – Bina # 2

MPPTCL (Y)

15:15 A/T due to mal-operation of carrier signal received at Bhopal. Problematic G3EI and G3EH prints of NSD 61 in PLCC panel replaced.

3.17 400kV Raipur

12.10.07 12:43

400kV Raipur – Bhilai # 2

POWERGRID (Y)

13:11 A/T on receipt of spurious D/T command at Bhilai end in PLCC channel-1 causing 3-ph tripping


of feeder from Bhilai end. 3.18 ---deleted---- (See 7.01) 3.19 400kV

Chandra-pur

13.10.07 15:21

400kV C’pur – Parli # 1

MSETCL (Y)

19:51 L/O trip at C’pur on receipt of D/T signal, a mal-operation. Reactor Back-up protection operated at Girvali (Parli) end and line charged without reactor at Parli.

3.20 400kV Dehgam

14.10.07 05:27

400kV Gandhar -Dehgam # 2 400/220kV ICT # 1

POWERGRID (Y)

06:06 06:42

Line and ICT tripped simultaneo-usly. Line A/T from both ends on operation of DPR. Tie CB 552 Trip delayed and after 221ms its LBB operated.

3.21 400kV Asoj

16.10.07 20:45

400kV Asoj – Wanakbori

GETCO (Y)

21:36 A/T due to operation of stuck breaker protection at Wanakbori TPS while S/off Unit # 5.

3.22 400kV Satpura

16.10.07 23:59

400/220kV 315MVA, ICT

MPPTCL 17.10.07 17:06

A/T from both sides due to 220kV Bus-II R-phase conductor snapping and operation of 220kV Bus Bar Differential Zone-II.

3.23 400kV Charania

17.10.07 15:19

400kV Chorania -Hadala

GETCO (Y)

18:17 A/T on transient Y-ph to E/F. Patrolling carried out, hence delay in charging.

3.24 220kV KAPS

18.10.07 13:01

220kV KAPS- VAV -I

POWERGRID (Y)

14:56 A/T in Zone-I on transient C-ph (A,B,C phases) to E/F.

3.25 220kV KAPS

18.10.07 13:01

220kV KAPS- VAV -II

POWERGRID (Y)

14:08 A/T in Zone-I on transient C-ph (A,B,C phases) to E/F.

3.26 400/220 kV Satna

19.10.07 12:17

400kV V’chal- Satna # 3

POWERGRID (Y)

12:44 A/T on transient Y-ph to E/F.

3.27 400kV Satpura

20.10.07 11:45

400kV Sarni – Indirasagar

MPPTCL (Y)

12:15 A/T on transient B-ph to E/F.

3.28 400kV Bhilai

23.10.07 13:38

400kV Korba –Bhiali # 2

POWERGRID (Y)

14:51 A/T on transient R-ph to E/F, A/R L/O due to persisting nature of fault.

3.29 400/220 kV Satna

23.10.07 14:23

400kV V’chal- Satna # 2

POWERGRID (Y)

14:49 A/T on transient R-ph to E/F.

3.30 400kV Bhadravati

23.10.07 14:55

400kV Raipur – B’vati # 2

POWERGRID (Y)

14:55 A/T on transient B-N fault and successfully A/R at both ends.

3.31 400kV Asoj

01.11.07 10:07


POWERGRID (Y)

10:24 A/T on transient R-ph to E/F and A/R operated successfully at Asoj end.

3.32 400kV Koradi

01.11.07 23:25

400kV Koradi- Chandrapur

MSETCL (Y)

02.11.07 19:51

A/T on B-N fault. Insulator string found bursted at Loc. No. 119.

3.33 400kV Bina

03.11.07 12:40

400kV Bina- Nagda # 1

POWERGRID (Y)


3.34 400kV Nagda

03.11.07 14:00


POWERGRID (Y)


3.35 400kV Nagda

04.11.07 11:56


POWERGRID (Y)



3.36 400kV Nagda

04.11.07 12:59


POWERGRID (Y)

21:44 A/T on transient R-ph to E/F. Line Reactor isolated from system at Nagda end due to B-ph Bushing Leakage and line synchronized without line reactor and holding successfully.

3.37 400kV Jabalpur

06.11.07 12:37

400kV V’chal- Jabalpur # 2

POWERGRID (Y)

13:27 A/T at both ends due to operation of reactor protection at VSTPP end & D/T received at JBP end.

3.38 400kV Koradi

10.11.07 16:25

400/220 kV 3x100MVA ICT - I

MSETCL

23:15 A/T on operation of differential protection. Unwarranted tripping suspected while dressing-up of wiring in the relay panel of ICT by M/s Siemens representative for SMS activities. ICT recharg-ed after thorough investigation and testing. Nothing found abnormal.

3.39 400kV Kasor

11.11.07 03:43

400kV Kasor – GPEC

GETCO (Y)

14:55 A/T due to Y-ph insulator string flashing at Loc. No.143(S).

3.40 400kV Bina

12.11.07 11:41


POWERGRID (Y)


3.41 220kV TAPS

14.11.07 11:23

220kV TAPS- Vapi

GETCO (Y)

12:25 A/T from both ends on transient C-ph to E/F.

3.42 400/220 kV Satna

23.11.07 17:26

400kV Satna – Bina # 4

POWERGRID (Y)

17:41 A/T due to mal-operation of relay at Bina end and D/T received at Satna end.

3.43 400kV Boisar

27.11.07 10:17

400kV Boisar - Padghe

POWERGRID (Y)

10:17 A/T on transient B-N fault and successfully A/R at both ends.

3.44 400kV Bhopal

02.12.07 22:02

400kV Bhopal – Bina # 1

MPPTCL (Y)

22:15 O/V stage-I protection operated at Bina end.

3.45 400kV Bina

02.12.07 22:00

400kV Bina- Gwalior

POWERGRID (Y)

03.12.07 05:52

A/T on operation of main-1 protection O/V stage-I.

3.46 400kV Indore

04.12.07 18:10

400kV Indore- Asoj # 2

POWERGRID (Y)

18:31 A/T on transient E/F.

3.47 400kV Raipur

14.12.07 02:15

400kV Bhilai -Raipur # 1

POWERGRID (Y)

20:57 A/T due to operation of Y-ph O/V relay at Bhilai end (429V). Replaced Y-ph CVT at Bhilai by spare one before taking feeder into service.

3.48 400kV Vapi

16.12.07 12:38

400kV Vapi – Boisar

POWERGRID (Y)

17.12.07 15:21

A/T on R-N fault ..

3.49 400kV Bhilai

18.12.07 08:48

400kV Raipur – Bhilai # 2

POWERGRID (Y)

10:28

3.50 400kV Bhilai

18.12.07 15:06

400kV Bhilai - Raipur # 2

POWERGRID (Y)

19:11

Tripping occurred due to wrng wiring which was rectified.

3.51 400kV Boisar

20.12.07 10:03

400kV TAPS – Padghe # 2

POWERGRID (Y)

21.12.07 18:22

A/T at Padghe end only due to open jumper of R- ph at Loc. No.107.


Annexure –4 Present status on recommendations pertaining to Protection of Inquiry Committee on grid disturbances of 25.02.2007 and 28.02.2007 Sl no

Recommendations Status

i) Both Main- I and Main –II protection on 400 kV Padghe- Nagothane Ckt-I is provided by ABB make REL 521 relays with same characteristic and settings thereby defeating the purpose of providing selectivity and discrimination of the fault. In line with Section 2 of CBIP Publication 274 of November 1999, Main-I and Main-II protection should be of different types and not necessarily of different make.

MSETCL intimated that on 400 kV Padghe – Nagothane ckt-I, Main-I and Main-II protections have been provided with different characteristic and settings at Nagothane end only. Regarding rest of the system it was agreed that as a first step all the constituents shall identify such feeders where both Main -I and Main-II protection are provided by relays with similar characteristic /settings. Constituents shall intimate the action plan for replacing or modifying the relays as per the recommendation of committee and the progress made by constituents with regards to these identified feeders will be reviewed by committee. In pursuant of the above decision of the 99th PCM, MSETCL had submitted the information regarding the feeders having similar Main-I and Main-II characteristics, in respect of Nagpur and Nashik Divisions. Committee once again requested all constituents to furnish similar information in respect of their systems. Till the relays are replaced with newer version having different characteristics for Main-I & Main-II characteristics, it was suggested that by swapping relays on different feeders, the objective of providing different Main-I & Main-II protection could be achieved at some of the S/Ss. Committee requested constituents to inform the compliance.

ii) The Committee observed that distance relay REL 521 does not have the feature of recording switching off of auxiliary DC supply to the relay as an internal event among recording of other related relay supervision parameters. For the grid disturbance of 25.2.2007, the time of switching off of DC auxiliary supply was very crucial

As agreed in 98th PCM MSETCL took up the matter of incorporating the time of DC supply off to relay as an internal event with M/S ABB .In reply ABB intimated that whenever DC supply is switched off, relay can not function and hence process can not be stored “DC off “ as an internal event in a memory, so suggestion made by enquiry committee can not be implemented.. Committee felt that reply of M/s ABB was satisfactory and suggested that as an alternative we can wire up watch dog contacts available on


information, which was not available. The possibility of incorporating the time of switching off of DC auxiliary supply as an internal event recording may be taken up with the manufacturer.

fascia to log as an event on SER provided in sub -stations. For future procurement this requirement may be added in the specification of relays itself.

iii) The triggering of disturbance recorders at Padghe substation gets initiated only with the relay operation. Therefore, disturbance recording would not take place if the relay has not operated. The Committee recommends that the DRs should also have analog triggering signal from voltage/current/frequency threshold to ensure generation of DR data.

Committee discussed the threshold values for current and voltages to trigger DRs during 98th PCM and arrived at 110% and 90 % for Voltages and 150% of SIL values for current. Some of the committee members felt that the values agreed do not demarcate clearly the normal operational variations and fault conditions and should therefore be reviewed. Also the suggestion given by MSETCL to incorporate intentional time delays along with threshold values to avoid frequent triggering of DRS needed to be discussed. Therefore, decisions were again reviewed by committee. Following Decisions were taken.

i) It was observed that high voltages are prevailing in some of the pockets in the grid and 110 % limit is reaching frequently which doesn’t indicate fault condition. After discussion it was agreed to provide for analogue triggering of DRs at 150 % 0f Voltages, which indicate abnormality in the grid.

ii) 90% of nominal voltage threshold value considered for DR triggering in 98th PCM was not clearly reflective of fault condition and may trigger DRs unnecessarily therefore 70 % of rated voltage is recommended for triggering DR without any intentional time delay.

iii) Also ratio of under voltage and over current will reflect the fault condition properly but members felt that due to practical problems of providing logic etc this may not be practically possible.

iv) Also, Committee felt that over current threshold value of 1.5 times of SIL limit is not indicative of clear fault condition and therefore 150% of rated secondary current may be adopted.


Although time delay of 1 sec can be given for triggering DRs.

v) Also as agreed in 98th PCM continuous down loading of DR out put to a dedicated PC is also recommended.

iv) The Committee expresses its concern that 400kV Padghe substation does not have compatible device to download the disturbance data recorded from the memory of the numerical distance relays installed on 400kV lines. The Committee recommends that every sub-station having numerical relays be provided with compatible data downloading device to facilitate analysis of the vital information.

MSETCL informed that data down loading

facility from numerical relays has been included

in their Substation Monitoring Schemes (SMS)

and would be made available within three

months time. GETCO has confirmed in the 99th

PCM of having data down loading facility with

them. All other constituents were requested to

follow suite and intimate the progress.

CSEB informed that this recommendation is in process of implementation. MPPTCL informed that this facility has been included in ERPC (Enterprising Resource Planning Scheme), which is under tendering process.

v) The simulation studies indicate that the distance protection scheme provided on some lines are under-reaching due to in-feed effect. Protection Committee of WRPC may look into this aspect and review the settings of 400 kV lines considering in-feed.

As agreed in 98th PCM Zone –III settings considering in-feed effect is to be arrived after due study and on case to case basis. It was suggested that each state should initiate studies starting with any one station in their system results of the study may be put up to Committee for further discussions. MSETCL informed that protection review group has been formed and the group will take up this issue as a part of their study activity. Constituents are once again requested to carryout study for one of the 400kV S/S in their system and put up to committee for further review. MSETCL was requested to pursue with the protection review group to take up the issue for Padghe S/S.

vi) Since the 400 kV Chandrapur-Parli T/c is a very important corridor for power flow, the relays on this line should be replaced at the earliest by latest type of numerical relays.

MSETCL has now confirmed that all the three feeders of 400 kV Chandrapur – Parli are fitted with numerical Areva make Micom- P 44 2 relays at both ends as main-I and main-II protection and the recommendation has been complied.


Meanwhile the feature of lenticular characteristics available in micromho relay may be used as an interim measure instead of circular characteristics feature being presently used.

vii) With the tripping of ± 500 kV Chandrapur-Padghe HVDC link, large quantum of power gets suddenly diverted to other alternative A.C. networks and usually results in tripping of a number of lines on power swings. The Committee recommends that with the tripping of the both poles of HVDC link, generation level at Chandrapur thermal power station of MSPGCL may be brought down automatically to prevent spread of the disturbance. WRPC may work out a suitable scheme in consultation with MSETCL

MAHAGENCO/MAHATRANSCO were requested to expedite action to formulate the scheme. MAHAGENCO and MAHATRANSCO were once again requested to pursue the recommendations in view of its critical nature.

viii) In the grid disturbance of 25th February, 2007, the ER-NR inter tie got tripped resulting in disconnection of NR grid from ER grid. Subsequently, some more inter-regional links between ER/NR and NR/WR have been added which may help in reducing the impact of a disturbance in a Region on other Regions operating in parallel. However, the committee is of the view that special protection scheme be worked out on priority and implemented between the various Regions operating in interconnected mode so as to minimize the impact of a disturbance in a region on other regions.

Matter regarding formulation of special protection scheme to avoid disturbance due to occurrence in other region has been referred to CEA New Delhi for further action. WRLDC informed that they are in process of carrying out studies in order to devise special protection schemes in the event of tripping of regional links. As NR, WR, ER and NER are interconnected with many 400kV and 220kV links, a composite study is required to arrive at SPS in connection with regional links.

f-3, midc area, andheri (east), mumbai - 400 093 durbaaya … · 2008. 4. 30. · mpptcl...

Documents