115pcm agenda final - wrpc.gov.in · Korba(E) Unit-3,4,5 (50 MW each) Overspeed/turbine trip BALCO Unit-1 &2 Over frequency . 2 Agenda for 115th Protection Committee of WRPC DSPM

LIST 1) Chief Engineer (LD), MSETCL, Kalwa.Fax-27601769/65 2) Chief Engr. (Trans O&M), MSETCL, Bandra. Fax No. 022 26598587. 3) S.E. (T&C), MSETCL, Aurangabad Fax-0240-2234220 /2346290 4) S.E (T&C), MSETCL, Pune. Fax-9520-2617532/2612342 5) S.E. (T&C), MSETCL, Nagpur. Fax-95712-2234220 6) S.E.(T&C), MSETCL, Nasik Road Fax-0253-2462422 7) S.E.(T&C), MSETCL, Vashi Fax--022-27662055 8) S.E.(Gen.Tstg), MSPGCL,Eklahre, Nasik Fax-95253-2810496/2810499 9) S.E. (Task Force), MSPGCL, Nagpur Fax- 0712-2591717. 10) Chief Engineer (Gen), GSECL, H.O. Baroda. Fax-0265-5512129/2344537 11) Addl. C.E.(Testing), GETCO, Baroda. Fax-0265-2351218 12) Chief Engineer(LD), MPPTCL, Jabalpur. Fax-0761- 2664343 /2282632. 13) E.D. (T&C),MPPTCL, Jabalpur. Fax-0761-2661696 14) Addl.C.E., MPPGCL, Jabalpur Fax- 0761-2660063/2665805 15) E.E. (SLDC), MPPTCL, Indore Fax-0731-2874515 16) Chief Engineer (LD), CSPTCL, Bhilai. Fax-0788-2282632/0788-383633 17) C.E. (T&C), CSEB, Raipur.Fax-0771-4066988/07759-226227 18) EE (T) , CSPGCL- Fax.No. 07789-226227 19) S.E.(T&C), CSPTCL, Bhilai. Fax.No. 0788 2281561 20) S.E.(T&C), CSPTCL, Raipur. Fax No.0771-4066988. 21) E.E.(T&C), CSPTCL, Bhilai. Fax No. -0788 2281561 22) EE, Division VIII(MRT),Elect. Dept; Goa Fax 0832-2735124. 23) Supdt.Engr., Electricity Dept., DNH, Silvasa. Fax : 0260-2642338 24) Executive Engr., Electricity Dept. DD. Fax : 0260-2250889 25) D.G.M.(O.S. ),N.T.P.C., Mumbai, Fax- 28216692 26) D.G.M.(EM), KSTPS,NTPC,KorbaFax 07759-233088/ 232440 27) DGM (EMD), VSTPS, NTPC, Vindhyachal Fax-07805-247713 28) DGM (EM-I),NTPC, SIPAT Fax-07752-246506/246691. 29) AGM(O&M), KGPP,Adityanagar, Surat Fax 0261-2861428/2861433 30) Sr.Supdt. (EM),Gandhar, NTPC Fax-02642-87402 / 87450 31) DGM (O.S.), WRLDC, Mumbai Fax-28235434 32) DGM, WRTS-I POWERGRID,Nagpur.Fax-95712-641366/2641496 33) Addl General Manager, WRTS-II,POWERGRID,Baroda Fax-0265-2480952 34) SME (E), TAPS-3&4,Tarapur Fax 02525-282001/282073 35) Maintenance Superintendant,TAPS –1 & 2,Tarapur.Fax- 02525-282121 36) SME(E), NPCIL ,Kakrapara Fax 02626-234266 37) GM(Maint.). T.Power., Ahmedabad.Fax-079-27506679 38) AGM (ET&A),TPC, Trombay. Fax –022-66687088 39) Dy.Gen. Manager,Dahanu TPS Fax- 952528-222576 40) Vice President, Reliance Energy, Mumbai Fax-30094488 41) GM (Electrical), JPL, Raigarh. Fax.No.7767-281995,281993. 42) Director (G M Division), CEA, New Delhi. Fax.No.011-26109750 43) AGM(OS), NSPCL, New Delhi . Fax.No.011 26717363/26717366 44) GM, KSK Mahanadi Power Co Ltd., Hyderabad- Fax.No.04023559930 45) Director (Tech & Projects), JSW Energy( Ratnagiri) Ltd., Fax.No. 022 67848393 46) GM, RGPPL,Anjanwel,Guhagar,Ratnagiri. Fax.No. 02359 241071

1 Agenda for 115th Protection Committee of WRPC

AGENDA FOR THE 115th PROTECTION COMMITTEE MEETING OF WRPC TO

BE HELD ON 6/7.09.2012 AT PUNE

ITEM NO.1: CONFIRMATION OF MINUTES OF 114TH PROTECTION

COMMITTEE MEETING.

Minutes of 114th PCM, held on 11/12.06.2012 at WRPC Mumbai, were circulated vide

WRPC letter No. Prot./114 PCM/2012/WRPC-6410 dated 27th June 2012.

Following correction/observations have been received :

1. Rinfra vide email dated 26.07.2012 have requested to add following sentence in

ITEM NO. 6.3 : Revised islanding scheme in R-infra Mumbai transmission network

of 114th PCM :

“Committee has opinioned that R-Infra can proceed in implementing the Revised

Scheme as presented during the meeting.”

2. Item No. 2.4(ii) Multiple tripping of 400 KV lines at 400 kV JSWEL, Jaigad

(Ratnagiri) sub-station on 17.03.2011: It is noted and confirmed by WRLDC/JSWEL

that these trippings were occurred on 17.03.2012. Hence the correction may be

noted.

Committee may discuss and confirm.

ITEM NO.2: SYSTEM DISTURBANCES

2.1: System disturbances in CSPTCL/CSPGCL system.

2.1 (i) Occurrence at Korba East (Extn) (DSPM) Station on 1.05.2012

At 10:34 Hrs on 1.05.2012, cascaded tripping of following lines, ICTs and generators

occured :

Kotmikala-Amarkantak-1 Ph to Ph fault, DPR operated

Kotmikala-Amarkantak-2 Over current

400/220 kV ICT at Korba(W) R & Y phase Overcurrent

Korba(E) Unit-3,4,5 (50 MW each) Overspeed/turbine trip

BALCO Unit-1 &2 Over frequency


DSPM unit-1 & 2(250 & 210 MW) Gen. elect. & reheater protection

220 kV Korba(E)-Mopka B-G fault, DPR operated

220 kV BALCO-Korba(E)-1&2 Alongwith generators at BALCO

220 kV DSPM-Banari S/c and 220 kV DSPM-Suhela S/c were already out of service due to

falling of tower. Also, 220 kV Korba(E)-Raigarh, 220 kV Korba(E)-Budhipadar-II & III

were kept out to control overloading on 220 kV DSPM-Korba(E) S/c.

Approximately, 940 MW loss of generation without any load loss has been reported.

Report received from WRLDC is enclosed at Annexure-2.1(i).

In the 114th PCM during discussion on Item No. 2.1(i) : System disturbance at 400 kV Korba

system in CSPTCL system on 19-04-11, Committee recommended that in the absence of

SPS, the over current setting of the lines in the area can be raised to 150% so that sufficient

time margin would be available to take corrective actions in the event of loss of line in the

area thereby avoiding overloading the other lines by cutting-off the load or backing down the

generation. Committee further suggested that WRLDC would device SPS in consultation

with CSPGCL/CSPTCL on urgent basis.

Committee may like to discuss the occurrence and WRLDC/CSPTCL/CSPGCL may

give the status on above recommendations of the Committee.

2.1 (ii) Occurrence at Sipat on 15.06.12 and 19.06.12

On 15.06.2012 and 19.06.2012 at NTPC Sipat there was a grid disturbance resulting in a total loss of

generation of the order of 2100-2300 MW at Sipat.

Incident on 15.06.2012 at NTPC Sipat:

On 15.06.2012 at 1832 hrs at NTPC-Sipat units # 1,2,4,5 were on bar generating 2347MW.

The bus and line arrangement at NTPC Sipat is shown in Annexure- (before the incident) and

Annexure- (after the incident). At 18:34:51 hrs B Phase of 400kV tie CT of IBT1 (400/132 kV) to

ICT1 (765/400 kV) at Bay 14 at NTPC Sipat burst and led to the tripping of IBT1 and ICT1 on Tee

Differential protection. During the explosion one broken insulator piece flew and damaged moose

conductor clamp of LA of IBT2(400/132 kV). This caused the conductor to snap and resulted in

tripping of IBT2 on transformer differential protection at 18:34:53hrs.


The Explosion of B phase CT of 14CT-B and splashing of hot oil caused following damages:

a. B phase CT of 14CT-B failed and completely damaged.

b. R & Y phase CT of 14CT-B and Y Phase CT of 14CT-A insulator got damaged.

c. 7 nos. Isolator stacks of Bay 13, 14 & 15 got damaged.

d. B-phase Circuit Breaker pole of 1452 breaker damaged beyond repair.

e. 1 no. IPS to twin Moose connector damaged in R-phase of IBT-2.

Approx. 20 meters of length of all 240 nos of control and power cables running in the main trench in

the vicinity of failed CT caught fire due to spillage of oil from CT and got damaged. These damaged

cables pertain to bay No 13 (IBT #1 main bay), 14 IBT#1 & ICT # 1 tie bay), 15 (ICT # 1 main bay),

16 (Raipur # 2 main bay), 17 Raipur # 2 and Ranchi # 1 tie bay) & 18 (Ranchi #1 main bay).

The tripping of the IBTs resulted in loss of station auxiliaries supply and the running units at Sipat

tripped as follows:

1) The Unit 2 tripped on low vacuum at 1836 hrs.

2) Unit 1 tripped at 1853 hrs, unit 4 at 1900 hrs and unit 5 at 1933 hrs.

The generation loss was around 2347 MW. The NTPC Sipat Engineers and staff quickly acted and

controlled the fire. Due to the above disturbance 400 kV Sipat-Raipur ckt 2 tripped at 18:40:44 hrs

and 400 kV Sipat-Ranchi tripped at 18:37:33 hrs. Further the tripping also led to high voltage in 765

kV and 400 kV networks and following elements tripped on High voltage.

1) 765 kV Seoni-Wardha 2 at 1900 hrs

2) 400 kV Seoni-Bhilai at 1853 hrs

3) 400 kV Seoni-Khandwa 1 at 1853 hrs

4) 400 kV Seoni-Bina at 1853 hrs

5) 400 kV Seoni-Khandwa 2 at 1900 hrs

6) 400 kV Seoni-Satpura at 1900 hrs

7) 765 kV Seoni-Bilaspur 1 at 1910 hrs

Restoration activities were taken up by Sipat and on 16.06.2012 by 1200 hrs around 2000 MW

generation was on bar. The ICT2(765/400 kV) and IBT2(400/132 kV) were charged. ICT1 and IBT1

remained out. While cable restoration work was in progress, another incident took place on

19.06.2012.

Incident on 19.06.2012 at NTPC Sipat:

On 19.06.2012 at 1615 hrs at NTPC-Sipat units # 1,2,3,4,5 were on bar generating 2150MW. At

16.16 Hrs on 19.06.2012 IBT-2 got tripped, which was the only source in service for 132KV

switchyard and in turn all station transformers got dead. On inspection it was found that LBB of 1552

(IBT-1) breaker operated leading to actuation of Bus Bar protection of 400 KV Bus-1. 400Kv Bus-1


became dead. All Bus #1 breaker 952, 1252, 2052 and 2452 got tripped. 400KV Bus-II was live

through Raipur # 1, Ranchi #2 and ICT#2. As IBT # 2 was charged from Bus#1 Main CB 1252 and its

dia i.e bay 10 & 11 were not commissioned, tripping of Bus #1 caused tripping of IBT #2.

This caused tripping of all running units at Sipat as follows:

Unit -2 at Sipat tripped immediately followed by tripping of unit-5 at 1623 hrs, unit- 4 at

1643 hrs and finally unit-1 at 1651 hrs. The generation loss was around 2150 MW and

resulted in high voltages in 765 and 400 kV networks.

Following lines tripped on high voltages.

1) 765 kV Sipat-Bilaspur 2 at 1653 hrs

2) 765 kV Seoni-Wardha 1 at 1653 hrs

3) 400 kV Raipur-Sipat 1 at 1653 hrs

4) 400 kV Seoni-Bina s/c at 1653 hrs

5) 400 kV Sipat-Ranchi 2 at 1653 hrs

6) 400 kV Bhilai-Seoni s/c at 1653 hrs

7) 400 kV Khandwa – Seoni 1 at 1653 hrs

8) 400 kV Seoni-Satpura at 1653 hrs

9) 400 kV Khandwa-Seoni 2 at 1653 hrs

There was no significant change in frequency due to incoming wind generation at that time. By 0230

hrs of 20.06.2012 all units at Sipat were synchronized.

A group comprising of representatives from WRPC, WRLDC, POWERGRID and NTPC met at

NTPC-Sipat on 29.06.2012 to analyze the events that led to the disturbance and suggest remedial

measures to prevent recurrence of the same. A report analyzing the grid disturbance at Sipat STPS on

15.06.2012 and 19.06.2012 is available on WRPC website.

The group recommended as following :

1) To explore the possibility of additional standby supply for auxiliaries from nearby 132 kV

system

2) The findings ( root cause analysis report of R & Y phase CTs by Areva).

3) New arrangement of sharing of shifting of loads between station and UATs

4) Procurement and replacement of the cables

NTPC may like to inform the progress on recommendations of the Group.


2.2: System disturbances in GETCO/GSECL system.

2.2(i) Occurrence at Sachin S/s in Gujarat on 27.03.2012

At 00:05 hrs on 27.03.12 due to flashover of B-Phase PT of 220 kV Bus-B, bus fault

occurred leading to tripping of all feeders and ICTs at Sachin S/S.

220 kV Sachin S/s is having double main and transfer bus switching scheme. The bus-

coupler was under planned shutdown for replacement of B-phase CT of 220 kV Bus-A.

Load loss of 204 MW was reported due to above without any generation loss.

Report received from WRLDC is enclosed at Annexure-2.2(i).

Committee may like to discuss.

2.2(ii) Occurrence at Kim S/s in Gujarat on 27.03.2012

At 14:15 hrs on 27.03.2012 GSEG-Mora-Kim and GSEG-Kim which were evacuation lines

for GSEG tripped on Y –phase distance protection. GSEG GT-1(52 MW) and GSEG

STG(52.1 MW) tripped due to loss of evacuation lines. Gujarat has reported that on

patrolling sugar cane wastes were found burnt below the locations 91 & 92. (distance 17.7

Km from Kim).

Report received from WRLDC is enclosed at Annexure-2.2(ii).


2.2(iii) Occurrence at Kakrapar APS on 4.05.2012

On 4.05.2012 at 17:50 Hrs CB of Kakrapar-Haldarwa-2 at KAPS end tripped on pole

discrepancy protection with C10x relay flag while normalizing the line. NPCIL have

intimated that on investigation ‘B’ pole closing circuit anti pumping relay NC contact found

resistive. The same was attended through spare contact of anti pumping relay (52 yC) and

closing loop made healthy.

Report received from NPCIL is enclosed at Annexure-2.2(iii).



2.2(iv) Occurrence at Nakhatrana S/s on 27.05.2012

At 10:50 hrs on 25.05.2012 backup protection operated at 220 kV Nakhatrana-Nanikhakhar-

II leading to tripping of KLTPS and ALTPS units and subsequently Nakhatrana s/s

experienced zero power. Planned shutdown of 220kV Nakhatrana-Nanikhakhar-I was

availed at 25.05.2012 for earth wire replacement work. Panandro –Kukma-II was under

outage due to permanent fault from 24.05.12 for repairing broken conductor. Due to heavy

loading on Panandro –Kukma-I and heavy wind in reverse direction, the induction effect

made it very difficult and dangerous to work on Panandro –Kukma-II and hence Panandro –

Kukma-I was switched off at 10:50 hrs to enable to carry out work on Panandro –Kukma-II.

This led to tripping of Nakhatrana-Nanikhakhar-II on back up protection due to overload and

other lines also tripping of KLTPS unit 1 & 2(unit 3 &4 were under forced shutdown) and

ALTPS unit 1(unit-2 was under forced shutdown) due to lack of evacuation.

Report received from WRLDC is enclosed at Annexure-2.2(iv).

GETCO may furnish the details and overcurrent settings so that they can be discussed.

2.2(v) Occurrence at Ichhapore S/s on 2.06.2012

220 kV Kawas-Haldarwa-I & II lines were switched off for controlling line loading of 220

kV Kawas-Ichhapore line. Also, planned shutdown for 220 kV Navsari-Sachin line was

availed on 2.06.12. Load on Essar complex (200 MW), Sachin S/s(200 MW),

Ichhapore(70MW) was catered by 3 lines namely 220 kV Kawas-Ichhapore, 220 kV Vav-

Ichhapore and 220 kV Vav-Sachin. At 16:15 hrs on 2.06.2012 a direct trip command from

Kawas end received during PLCC testing carried out at Kawas 220 kV Kawas-Ichhapore

line. Tripping of Kawas-Ichhapore line led to overloading of 220kV other two lines and

eventually tripped on over current protection causing zero power at Ichhapore and Sachin s/s.

Load loss of 47 MW was reported during above incidence. Report received from WRLDC is

enclosed at Annexure-2.2(v).



2.3: System disturbances in MPPTCL/MPPGCL system.

2.3(i) Occurrence at 220 kV Jabalpur S/S and Bargi HPS on 27.05.2012.

MPPTCL have intimated that on 27.05.2012 at around 21:45 hrs 132 kV B-Phase CT of bus-

coupler bay at Bargi HPS got burst due to delayed opening of 132 kV breaker of Bargi-

Jabalpur-II at 220 kV Jabalpur s/s and created bus fault tripping three transformers(220/132

kV) and all outgoing feeders from remote end including 45 MW Unit -1. The B-phase pole

of 132 kV breaker of Bargi-Jabalpur-II at 220 kV Jabalpur s/s also got burst. There was load

loss of around 260 MW and generation loss at Bargi HPS at 31 MW.

Detailed report received from MPPTCL is enclosed at Annexure-2.3(i).


2.3(ii) Occurence at Satpura S/s on 5.04.2012

MPPTCL have intimated that on 5.04.2012 at 00:30 hrs at Satpura TPS, 220 kV main Bus-I

PT ‘B’ phase (SCT make) got burst. Consequently busbar differential zone-I(R&B) phase

and zone –II(R phase) operated resulting into tripping of all lines and generators connected

on Bus-I and Bus-II. Generation loss of 470 MW has been reported. To avoid such

recurrence the location of existing PTs of 220 kV Bus-I have been shifted.

Detailed report received from MPPTCL is enclosed at Annexure-2.3(ii).


2.3(iii) Occurrence at 132 kV Bina S/s on 4.05.2012

MPPTCL have intimated that on 4.05.2012 at 07:45 hrs one tower of 132 kV Bina-Rajghat

line at location no. 256 collapsed and 132 kV Bina-Rajghat tripped on DPR on AN phase and

current fed was of the order of 1592 A. Simultaneously 132 kV Bina-Chanderi line (which

was on the same tower) DPS operated on C-phase zone-I but A phase did not trip ( later CB

trip coil found burnt). After collapsing and tilting of the tower the fault came on A phase

and started feeding current approx 780 A in Chanderi feeder. Due to continuous feeding of

fault current in A phase of 132 kV Chanderi feeder the 160MVA and 3x40 MVA

transformers at Bina S/S tripped at on E/F alongwith 132 kV Sagar, 132 kV Ashoknagar at


Bina end on E/F. 132 kV Sironj and Basoda feeders tripped from other end. Also, BORL

1&2 tripped from BORL end.

Detailed report received from MPPTCL is enclosed at Annexure-2.3(iii).


2.3(iv) Occurrence at 220/132 kV Ujjain S/s on 7.05.2012

MPPTCL have intimated that on 7.05.2012 at 15:16 hrs 132 kV Ujjain-Ghosla line tripped

from both ends on C phase zone –I indication at Ujjain end and over current E/F from remote

end. At Ujjain end B phase pole of MOCB got stuck up which resulted in heavy fault current

fed and hence total supply failure at 220 kV/132 kV Ujjain s/s.

MPPTCL in their report have recommended for replacement of MOCB (very old:1977 make)

with SF6 breaker.

Detailed report received from MPPTCL is enclosed at Annexure-2.3(iv).


2.3(v) Occurrence at 220kV Barwaha S/s on 11.05.2012

MPPTCL have intimated that on 11.05.2012 at 00:58 hrs Y phase LA of 220 kV Itarsi line at

Barwaha S/s got burst. DPR of this line at Barwaha s/s did not operate due to VT fuse fail

hence line tripped on back up E/F. Because of delayed tripping all 220 kV lines from

Barwaha s/s tripped on zone-II from remote end except 220 kV Handiya line. During this

incidence 220 kV Omkareshwar-Barwaha and Omkareshwar-Nimrani alongwith 5 running

machines at Omkareshwar.

Detailed report received from MPPTCL is enclosed at Annexure-2.3(v).



2.4: System disturbances in MSETCL/MSPGCL system.

2.4(i) Occurrence at 220 kV Kalwa on 12.06.2012 at 17:05 Hrs

WRLDC vide fax dated 12.06.2012 have intimated that on 12.06.2012 at 17:05 Hrs 400 kV

Bus-I and 220 kV Bus tripped due to blasting of R phase CT of spare ICT leading to tripping

of following lines (based on SCADA information):

400 kV Kalwa-Padghe-II,

400 kV Kalwa-Kalyan,

300 MVA ICT-I

500 MVA ICT-III

220 kV Kalwa-Kalyan

220 kV Kalwa-

220 kV Kalwa-Trombay

220 kV Kalwa-

Fax message received from WRLDC is enclosed at Annexure-2.4(i).

WRLDC/MSETCL is requested to furnish complete details. Committee may like to

discuss.

2.4(ii) Occurrence at 220 KV S/S Khaparkheda on date 19.03.2012

MSETCL have intimated that on 19.03.12 at 20:43 hrs Bus bar protection operated due to

the initiation of arc across the R, Y & B Poles (i.e. between blades & jaws) of the 29C

Isolator of GT4 bay and is attributed to the imperfect closing of the 29C Isolator.

Details of trippings at Khaparkheda S No

Name of feeder / equipment

Window Indications

Relay Indications (RYB nomenclature)

1. Busbar protection for 220 KV Transfer bus (i.e. Auxiliary bus) operated and tripped the TBC breaker through its 96 busbar trip relay:

Busbar Protection Operated

Busbar scheme ABB – RADSS with TR and R, T & U flag indications.

i. 220 KV TBC BB Prot optd 96 relay optd. 2. 220 KV GT4 E/F opt. (at PCR

end); LBB operated WI on

GT4 control panel and RTU

O/C-E/F relay; LBB relay (B/U + LBB Alstom- KCEG 142), MTR optd.


DC SCADA IED at GCR end

3. Consequent to operation of the LBB relay of GT4 all breakers connected to 220 KV Main Bus1 including Bus-coupler at Khaparkheda GCR tripped through respective Busbar trip relay 96 as follows:

--- ---

i. 400 KV Koradi ckt BB Prot optd. 96 relay optd. ii. 220 KV Ambazari ckt1 BB Prot optd. 96 relay optd. iii. 220 KV Kanhan ckt2 BB Prot optd 96 relay optd.iv. 220 KV Kaulewada ckt1 BB Prot optd 96 relay optd.v. 220 KV Kalmeshwar ckt BB Prot optd 96 relay optd.vi. 220 KV Wardha ckt BB Prot optd 96 relay optd.vii. 220 KV GT1 MTR Optd 96 relay optd.viii. 220 KV GT3 MTR Optd 96 relay optd.ix. 220 KV GT4 MTR Optd 96 relay optd.x. 40 MVA Stn T/F1 MTR Optd 96 relay optd.xi. 40 MVA Stn T/F3 MTR Optd 96 relay optd.xii. 40 MVA Stn T/F4 MTR Optd 96 relay optd. xiii. 220 KV Bus Coupler MTR Optd 96 elay optd. There were no trippings at Remote ends. Details : Outage was availed by construction wing on date 19.03.2012 on 220 KV Main bus2

at 220 KV S/S Khaparkheda for connecting the bus2 side jumpers for the proposed

commissioning of two new 220 KV circuits to new Khaparkheda S/S. For availing this

outage all the 9 bays that were connected to 220 KV Bus2 were shifted to 220 KV Bus1

through TBC by the S/S operating staff in the morning session. After completion of the

jumpering work by construction, operation of restoration of normalcy of bays was taken up in

hand by S/S operating staff at 17:56 hrs. Shifting operation for six 220 KV bays (viz:

Ambazari2, Kanhan1, Purti, Kaulewada2, GT2 & Stn T/F2) from Bus1 to Bus2 was

completed by 20:15 hrs.

Shifting operation for 7th bay (i.e. GT4 bay) were underway; at the juncture of tripping of

main breaker of GT4 heavy sparking across all the six R, Y & B pole contacts of 29C double

break isolator of GT4 bay (at 20:43 hrs) was observed by the switchyard operating staff.

Subsequently all the breakers connected to 220 KV Main Bus1 at Khaparkheda S/S tripped.

Single Line Diagram showing the relevant details of tripping is enclosed at Annexure-2.4(ii).


Analysis of Occurrence :

• MSETCL have intimated that they have analysed the occurrence and main cause of

occurrence is the heavy arcing that took place across all the R, Y & B pole contacts

(i.e. jaw & blade) of the double break isolator 29C (i.e. TBC side isolator) in GT4 bay

during shifting operations. Though after post occurrence, the correct closing and

opening operations of 29C isolator of GT-4 bay were confirmed in presence of the

CE, EHV CC O & M Zone, Nagpur, SE, EHV O & M Circle, Nagpur, EE,EHV O &

M Division, Nagpur and the undersigned, it was felt that there must have been some

gap left between jaw and blade of 29C isolator during pre-occurrence shifting

operation. This might not have been noticed during night hours. At this instance GT4

was running at @183 MW of power. Thus the current of @500A was initially broken

across the imperfectly closed poles of the isolator which initiated arcing. The length

of arc and the magnitude of flashover current gradually increased and subsequently

attained a fault value. The estimated fault current is @10KA.

• This heavy arcing fault was in-zone fault for TBC bus (i.e. Auxiliary bus) and thus

selective operation of Busbar protection (ABB-RADSS) for transfer bus and

subsequent tripping of TBC breaker is IN ORDER..

• The occurrence took place at the very instance of hand-tripping of main breaker of

GT4 during shifting operation. Hence the GT4 remained connected to Main Bus1 (i.e.

29A isolator was in closed position) also the ‘NIT’ switch remained in ‘INTER’

position.

• While other sources connected to the bus-I fed the fault through the TBC, The GT4

directly fed the fault with its own fault contribution (estimated fault contribution by

GT4 @1KA). This caused Earth Fault relay of GT4 to operate at PCR end and issued

the trip command to TBC & Main breaker. However the fault current did not seize as

the Generating Unit-4 was directly feeding the fault. Hence, subsequently its LBB

protection operated and tripped all the breakers connected to Bus1. Hence the

operation of E/F & LBB protection of GT4 and consequent tripping of all breakers

connected to 220 KV Main Bus1 at Khaparkheda is IN ORDER.

• The sequence of operations for shifting of the GT4 bay was later verified and found

OK.



2.4(iii) Occurrence at 400 KV S/S Khaparkheda on date 05.04.2012

MSETCL have intimated that at 400 kV Khaparkheda s/s at 12:41 on 5.04.2012 all breakers

connected to 400 KV Bus1 (one and a half bus arrangement) tripped at 400 KV GCR

Khaparkheda through respective Busbar trip relay 96 on operation of LBB protection (50Z1)

(Areva Micom make P123 type) of GTR bay installed in MAHAGENCO GCR, for Bus-I.

Details of trippings at Khaparkheda S No


Window / SCADA

Indications


1 LBB relay of GTR bay operated at Mahagenco’s PCR end and tripped following breakers connected to 400 KV Bus1 through respective BB trip relay 96 as under:

---- LBB relay 50Z1 (Areva Micom P123) operated at PCR with trip LED indication. Fault data (Record 25): Ia = 0; Ib=1.25A; Ic=0; Faulted Phase: None; Tme: 12:41:25:22; Dt 05.04.12

i. 400 KV GTR 96 relay optd 96 relay (GTR was OFF) Time: 12:41:44:174 hrs)

ii. 3X167 MVA 400/220 KV ICT1

96 relay optd 96 relay (Time: 12:41:44:174 hrs)

iii 3X167 MVA 400/220 KV ICT2


iv 400 KV Stn 5A 96 relay optd 96 relay (Time: 12:41:44:174 hrs) v 400 KV Stn 5B 96 relay optd 96 relay (Time: 12:41:44:174 hrs)

There were no trippings at Remote ends. Single Line Diagram showing the details of tripping is enclosed at Annexure-2.4(iii). On enquiry with MAHAGENCO it was intimated that GTR was already OFF. The pre-

synchronisation trials of the GTR bay were in progress and the relay operated at the instance

of switching OFF / ON the auxiliary dc to the Control & Relay panel. This trial was a part of

the routine test. However at the instance of switching of auxiliary supply, the ‘any trip’ pulse

from MTR (Master Trip Relay) was active to the LBB relay as the MTR was not resetted.

The numerical busbar scheme Sifang CSC 150 is provided at 400 KV Khaparkheda GCR.

The in-built LBB function of this relay is used for LBB protection for all the bays except

GTR. As the control of GTR bay is with Mahagenco, the LBB relay for this bay is also under

the purview of Mahagenco and the LBB command for GTR is externally connected to the trip


bus of busbar scheme. The matter of undesired operation of the LBB relay has been taken up

with MAHAGENCO and with M/S Areva.

As one and a half breaker bus arrangement is provided at GCR, the breakers connected to

Bus-1 & Bus-2 are clearly identified; hence isolator interlock is not provided for

identification of breaker. In the present scheme the LBB command of GTR is therefore

directly connected to the trip bus without such interlock.

The matter for review of the protection scheme for introduction of Breaker or Isolator

interlock is also taken up with M/S Easun Reyrolle Ltd.

The tripping of breakers connected 400 KV Bus-1 consequent to operation of LBB did not

cause any interruption of supply, since there is a one and a half breaker bus arrangement. The

GTR was already OFF and other bays were being fed through respective Tie breaker / Main

breaker.


2.4(iv) Occurrence at 220 KV S/S Warora on date 13.05.2012

MSETCL have informed that On date 13.05.2012 at 08:58 hrs 220 kV Bus bar Protection

(REB 500 ABB Make) of 220 KV WPCL bus operated and tripped following breakers

through respective B/B trip relay 96 including bus sectionalizer breaker

S No


Window Indications


a 220 KV WPCL Ckt-1 nil 96 BB trip relay b 220 KV WPCL Ckt-2 nil 96 BB trip relay

Trippings at Remote ends :

S No

Name of S/S Name of the feeder

Window Indications Relay Indications

1 220 KV GCR Chandrapur

220 KV Warora Distance protection trip

Dist Zone-2, R-Y-N, XTF=40.6 KM, 86

2 220 KV Wani 220 KV Warora Distance protection optd.

Dist Zone-2 R-Y,86

3 220 KV Wardha 220 KV Warora Distance protection optd.

Dist Zone-2, R-Y-N, XTF=73 KM,86

4 220KV Hinganghat 220 KV Warora Distance protection optd.

Dist Zone-2 R-Y,XTF=48.76 KM,86


Details of occurrence : On date 13.05.2012 at 08:58 hrs, bursting sound was heard from the switch yard of 220 KV

S/S Warora, followed by total a. c. failure at this S/S. On Yard inspection ‘R’ ph CT (Make:

SCT Gaziabad, Sr. no.: 2009/1766, Mfg year: 2009) of 220 KV WPCL Bus-sectionalizer

found to have burst. The failure caused damage to R-ph pole of Siemens make bus-

sectionalizer breaker and R-ph insulator of incoming side and outgoing side isolators and

carbonisation of adjoining Y-ph CT. 220 KV Bus bar Protection scheme (ABB - REB 500)

provided for 220 KV WPCL bus operated alongwith the newly commissioned 220 KV Bus

bar Protection scheme (Make: NR-RCS 915 ) provided on 220 KV old Warora bus which

was kept on alarm mode.

Single line diagram showing the details of tripping is enclosed at Annexure-2.4(iv).

Analysis of occurrence :

• The work of extension of existing 220 KV bus in the extended section of

switchyard, providing of bus-section breaker and allied work of providing

switchgear, protection and SCADA etc was carried out by M/S WPCL on turnkey

basis. On date 13.05.2012, at 08:58 Hrs the R-ph CT of 220 KV Bus-sectionalizer

burst which created bus fault in WPCL bus and consequently 220 KV Bus bar

Protection (ABB-REB 500) of 220 KV WPCL bus operated and tripped 220 KV

WPCL Ckt-I & II breakers through respective B/B trip relay 96 including Bus-

sectionalizer breaker at Warora end is in order.

• Remote end indication at Chandrapur, Wani, Wardha, Hinganghat indicate the

involvement of R & Y phases in the fault, indicating that the smoke of the burst R-

ph CT must have created a bus fault w. r. to Y phases. This fault was being fed

from existing 220 KV Warora bus. The Newly commissioned numerical 220 KV

Bus bar protection scheme (RCS 915 Make-NR) provided for 220 KV old Warora

bus operated but since the same was kept on alarm mode so as to confirm its

stability on through fault, no tripping at local end at Warora S/S occurred. Thus

220 KV bus fault on 220 KV old Warora bus caused all the sources to trip at their

respective end on distance zone-2 (R & Y phases). Tripping of all sources at

remote end caused total a.c. failure at 220 KV S/S Warora.

• The occurrence caused loss of generation @436 MW of M/S WPCL. Also the load

of Warora Railway TSS of @ 2 MW and local load of @ 43 MW was affected.


The load of @ 385 MW of Hinganghat, Wardha, GCR Chandrapur and Wani

feeders was thrown off to other lines in the grid. The 220 KV grid however

remained stable.

• The newly commissioned 220 KV Bus bar protection scheme (RCS 915 Make-NR)

which was kept on alarm mode to confirm its stability on through fault is now kept

on trip mode.


2.4(v) Occurrence at 220 KV S/S Butibori on date 19.06.2012

MSETCL have informed that at 03:50 hrs on 19.06.2012 at Butibori S/S all breakers

connected to 220 KV Main Bus-1 including Bus-coupler tripped through respective 96 BB

tripped.

Details of trippings at Butibori: S No

Name of the feeder / equipment


1 LBB Protection of 220 KV Indorama feeder operated and tripped all breakers connected to 220 KV Bus 1, including Bus-coupler, through respective 96 BB trip relays, as follows:

-

2 220 KV Indorama LBB protection optd 2/50Z, 96 3 220 KV Inox i)Pilot wire prot optd.

ii)Pilot wire defective 96

4 220 KV Buscoupler Nil 96 5 50MVA 220/33 KV T/F-3 Nil 96 6 220 KV Koradi Trip relay optd. 96

There were no trippings at remote end.

Single Line Diagram of 220 KV S/S Butibori, showing relevant details of tripping is

enclosed at Annexure-2.4(v).

Analysis of occurrence : MSETCL have analysed the incidence as below :

1. There was a fault on 11 KV bus at M/S Indorama company emanating from 220 KV

Butibori S/S. For this fault, 11/33 KV Tie 4 & 5 T/F tripped on over-current relay at


consumer end with fault current @ 1.71 KA and 1.63 KA on 33 KV side in about 232

msec.

2. The matter of operation of LBB protection of 220 KV Indorama feeder was

investigated in detail and the problem of contact of trip relay RXMS1 was detected.

It was found that the D.C logic of LBB relay on 220 KV Indorama panel at 220 KV

Butibori S/S was through via bus bar protection trip relay (96) contact which was

found stuck in make condition. The fault current was above the pick up setting of

LBB relay . Current setting of LBB relay is 0.8 A sec(CTR-400/1A) that is 320 A

primary with 200 msec timer setting. As D.C. logic of the LBB relay was already

through and fault current was above pick up setting of LBB relay resulting into

operation of LBB protection of 220 KV Indorama feeder. The problem of contact of

trip relay RXMS1 was later attended and confirmed that the D.C. logic of LBB relay

is not through.

3. It is to note that back up protection of 220 KV Indorama feeder did not operate for the

above fault as the fault current was just above the pick up setting of LBB relay and

Earth fault relay will take time @0.5Sec to operate. The setting of Back up O/C and

E/F relay (Make: EE, Type: CDD) are:

CTR PS TMS O/C R & B 400/1A 100% 0.08 E/F 40% 0.08

4. The total fault current shown at 33 KV level at M/S Indorama end is @3.34KA

(Ref: Annexure:2). For this fault, The fault current shown by 220 KV side relay of

220/33 KV T/F at 220 KV Butibori S/S end is @500 A. From this it appears that

@500 A fault current is fed from 220 KV bus at 220 KV Butibori S/S. For 500 Amp

fault current the time require for E/F relay to operate is calculated as under:

500A/160=3.1 means for 3 times current TOP is 6.302 and TMS setting for E/F is

0.08. Thus time requires to operate E/F relay comes out to be @504 msec.

From this it appears that before operation of E/F relay of T/F, the LBB relay of

Indorama feeder operated with pick up setting of 320 A primary with 200 msec timer

setting.


5. The occurrence caused interruption to EHV consumers M/S Indorama & M/S INOX

(Load 1MW and 2.5 MW respectively) and also local 33 KV load of @ 12 MW

was affected. The load @ 55 MW on 220 KV Koradi feeder was shared by other

feeders and the grid remained stable.

MSETCL have further submitted that the operation of LBB protection of 220 KV Indorama

feeder is undesirable. In view of this, the D.C. logic of LBB relay of all feeders checked and

confirmed that it is not through. The operation of LBB relay of 220 KV Indorama feeder was

mainly due to contact stuck up problem of trip relay RXMS1, which activated D.C. logic of

the relay. As such the matter is discussed at the SPC meeting dt.20.06.2012 for providing the

supervision to the ‘LBB initiated’ command. It is decided in the SPC that the decision to

provide ‘LBB initiation supervision’ shall be taken in next SPC after detail discussion.


ITEM NO. 3: Other points:

ITEM NO. 3.1: Implementation of SPS for Agra-Gwalior corridor. NRLDC vide letter dated 5.8.2012 requested for discussion and finalization of setting for

SPS for tripping of Agra-Gwalior lines or Bina-Gwalior lines.

Following comments were communicated to NRPC vide letter

No.WRPC/Protection/SPS/2012/1287 Dated 16.08.2012.

1. SPS designed by NR is preemptive action to control overloading of Agra-Gwalior and Bina-

Gwalior corridor between WR and NR and therefore summated values for both the circuits

may be considered for operating load shedding in NR.

2. Proper load shedding in NR only would reduce the flow on above corridor. The effect of

backing down of generation in WR would not be so sensitive to reduce the flow on above

corridor. Therefore, Case-1 and Case-2 actions to be taken by NR constituents are in order.

3. As far as backing down of 500 MW generation in Western Region is concerned, We have

requested WRLDC to carry out sensitivity study to find the effect of backing down/tripping

of various generators on flow on Bina-Gwalior and Agra-Gwalior lines.Therfore

presupposing backingdown of generation at VSTPS or Korba may not be appreciable.


4. In case of angular separation between Gwalior and Agra beyond permissible limit planned

separation between the two grids alongwith load shedding schemes may also be planned/

incorporated.

5. Sufficient time delay and interlocks are required to be provided for backing down/tripping of

generation in WR after ascertaining that sufficient load shedding is carried out in NR and

thereafter according to flow on Agra-Gwalior and Bina-Gwalior lines backing down

quantum can be decided.

6. Appropriate action plan may be devised in case of tripping of both Agra-Gwalior lines

7. Above points alongwith the sensitivity study results submitted by WRLDC would then be

discussed in ensuing Protection sub-Committee of WRPC and thereafter in TCC & WRPC

forum and then the outcome would be submitted to NR.

Accordingly WRLDC vide letter dated 21.08.2012 have submitted the study results of

sensitivity of generation backing down in WR for implementation of SPS for the contingency

arising out of import from WR to NR on Gwalior- Agra corridor. The same is enclosed at

Annexure3.1(i). Scheme approved in 18th NRPC meeting, received from NRLDC is

enclosed at Annexure-3.1(ii).


ITEM NO. 3.2: Repeatation of PLCC frequency for various 400 kV lines under WRSS-

II & Mundra UMP scheme

ACE(Transmission), GETCO during 114th PC meeting intimated that PLCC frequencies

already in use on 400 kV at GETCO s/s are repeatedly used byPGCIL for 400 kV D/c

Ranchodpura(Vadavi)-Limbdi(Chorania), 400 kV D/c Ranchodpura-Zerda(Kansari), 400 kV

Ranchodpura-Bachau and 400 kVLimbdi(chorania)-Mundra commissioned under WRSS-II

and Mundra UMPP scheme without any concurrence fromGETCO. He further intimated that

as per technical report, CE1, IEC 663:1980 clause No. 4.1.2.C, “The same frequency maybe

used for two different PLCC stubs working on lines forming common system if two are

separated by at least two line sections with intermediate sub stations.”

He further intimated that PGCIL has used frequencies already used in service for GETCO

without any concurrences from GETCO for other stations and warned that the practice of

utilizing repeated frequencies for PLCC may cause mal operation of system further causing

instability in the grid. He further intimated that 8 KHz band is used for every link.


PGCIL/WRLDC representative intimated that PGCIL might have used repeated frequencies

due to non-availability of the bandwidth. He further intimated that elsewhere 4 KHz band is

used safely in the system and the problem of non-availability of bandwidth can be resolved if

4 KHz band is used in GETCO. However, he would confirm the same after consultation with

WR-II. PGCIL/WRLDC were requested to followup the matte with WRTS-II, PGCIL.

ACE(TR), GETCO vide letter No. CE(Tr)/SE/Telecom/PLCC/39/1012 dated 23.07.2012

addressed to PGCIL, WR-II (copy enclosed at Annexure-3.2 ) have intimated that despite

several reminders to PGCIL regarding repeated use of PLCC frequencies for 400 kV

transmission lines under WRSS-II & Mundra UMPP scheme, matter have not been

responded/solved by PGCIL.

PGCIL, WR-II may clarify. Committee may like to discuss.

ITEM NO. 3.3: Review of low frequency and high frequency trip setting for generating stations in WR.

During recent grid disturbance in NR/ER/NER on 31.07.2012, WR grid was isolated from

rest of NEW grid and WR frequency almost touched 51.5 Hz. Following units reported to

have tripped in WR during isolation of WR from NR/ER.

WRPC vide letter dated 16.08.2012 have requested to furnish the information regarding unit

tripping and alarm settings for under as well as over frequency by various generators in WR.

The settings received from various generators are enclosed at Annexure-3.3.

It is necessary that all the generator trip settings required to be staggered to avoid

simultaneous trippings of all generators at given station/control area/State. In such an event

total station may face blackout and may result into low frequency in the grid in the event of

tripping more than required generation.

Committee may like to discuss and recommend for appropriate settings.

ITEM NO. 3.4: Protection Auditing by CPRI

During the meeting held at CEA on recent grid disturbance in NR, importance of protection

auditing was discussed. All the members are familiar with protection of power system but

new to auditing of the same. In order to address the system security concerns protection


audit of substations is essential and actively being pursued in India. The aim of the audit is to

review the protection philosophy, relay coordination and protection settings, healthiness of

DC system, healthiness of communication link with respect to protection system, healthiness

of Time synchronization of generating Units, healthiness of disturbance recorders and event

loggers, protection testing procedures and protection system technology.

Accordingly, Director General, CPRI, Bengaluru & experts from CPRI have been requested

to make a presentation on the ins and outs of protection auditing on7.9.2012 at 14:30. Hrs.

ITEM NO. 4: Any other issues.

ITEM NO. 5: Date and Venue of the next meeting.

dhakate sir

Text Box

Annexure-2.1(i)

dhakate sir

Text Box

Annexure-2.2(i)

dhakate sir

Note

Completed set by dhakate sir

dhakate sir

Text Box

Annexure-2.2(ii)

dhakate sir

Note

Completed set by dhakate sir

dhakate sir

Text Box

Annexure-2.2(iii)

Preliminary report on the occurrence on 25th May, 2012 at 220166 kV Nakhatrana substation (SIS) in Guiarat:

At 10:50 hrs on 2sth May, 2012 there was an occurrence at 220166 kV Nakhatrana S/S due to backup protection operation of 220kV Nakhatrana- Nanikhakhar-ll leading to tripping of KLTPS(Panandr0) and ALTPS(Akrimota) units. Subsequently 220KV Nakhatrana substation experienced zero power.

The antecedent conditions (at 10:48 hrs) to the incident are given under:-

1. NEW Grid Frequency: 49.92 Hz. 2. WR Demand Catered: 33732 MW (Approximately.) 3. Net Inter Regional Export: 251 1 MW

Constituent-wise generation and demand details prior to the event (As per WRLDC SCADA data) at 10:48 hrs:

-- -- --

7 - - -- - -- -

I __ - - -- Generation(in - MW) - - - - . --

WR Constituents I Demand(in MW) Thermal L Hydro I I Gas Wind Solar

---A - -

I Gujarat --

10346 8673 I 76 1276 33 I --- Maharashtra ----

15100 1-- 8639 594 N/A N/A - - ---- -- - - - - -- -- - - - - - - -

Madhya Pradesh 4644 --- - - 2263 1 161 -- - - -- - - -- -- - - -- -

Chhattisgarh - - -- - -- 2646 I 2025 i 0 0 - - - - -- - .- . -- -- - -

Goa I 346 0 0 - -- - 0 - - -- - - . . .. - . - -- -- .

I DD 0 0 0 1 54 - - - - . . . . -. - -. - -- -- --

DlVH : 478 0 0 I

L - i 0 I .

ISGS --- 12816 1022 0 - -~ ~

- .- - -. --- -- . -

Total - - - . . . -. - - - - - -. 33714 34416 1853 1276 I 331 -- .- - - -- -

Power flow on major lines in the area (prior to the incident) at 10:48 hrs:

"As per W i i i D C SCADA data

I I 1 repaicemehi \,licrk : 7 1 22G k'v' Nakhairana-Xanikhaki~ai - ii j 0 - 1 8 I 220 kV Panandhro-Nanikhaithar - II ; 9 1 220 kV Nakhatrana-Akrimoia - I I ? $ 226 k?' I'Jakhatrana-Akrim~ia - I I

6 0

16 --

23 -

Generating Units' status(prior to the incident) at 10:48 hrs:

( 2 1 ALTPS 2 x 125 1 100 -1 *As per WRESCADA data.

m T b 4 a r n e of the Generating Unit I I

Event Overview: 220 kV Panandhro-Anjar lines are made LlLO at Kukma and Nakhatrana- Akrimota- II is LlLO at Jamanawada (kept in according to requirement). Panandhro-kukma-ll was under outage due to permanent fault from 17:05 Hrs of 24.05.2012. Planned shutdown of 220kV Nakhatrana-Nanikjakhar-l was availed at 08:20 Hrs on 25.05.2012 for earth wire replacement work. Maintenance work for repairing the broken conductor of 220kV Panandhro- Kukma-ll was also under progress. Due to heavy loading on 220kV Panandhro-Kukma-l and heavy wind in the reverse direction, the induction effect of 220 kV Panandhro-Kukma-l was significantly felt. It was extremely difficult and dangerous to work on line-2. So for safety purpose 220 kV Panandhro-Kukma-l was switched off at 10:50 Hrs so to enable to carry out work on line 2.

At 10:50 Hrs 220kV Panandhro-Kukma-l was opened for carrying out work on line 2 220kV Nakhatrana-Nanikhakhar-ll tripped at Nakhatrana end on back-up protection due to overload. It resulted in tripping of KLTPS Unit1 & Unit 4 (Unit 3 84 were under forced shutdown) and ALTPS Unit 1 (Unit 2 was under forced shutdown) due to lack of evacuation. Resulted in tripping of other 220 kV lines from Nakhatrana Substation.

l nstalled Capacity(MW)

The sequence of tripping is given under as per the SOE data retrieved from WRLDC, SCADA.

- Actual Generation (in MW) *

d K m I 2 x 70.2 x 75

; Si / Name of the transmission element I Time of Tripping 1 Time of Restoration ;

136 I

L 1 - I I ---- i 2 I 220 kV Panandhro-Akrimota 1 10:5@ I 11:15 -- 2

No. ( 1 1 220 kV Nakhatrana-Nanikhakhar - II

. -- - ~

' - . . . ,. a , : -..:. . , n . . . ?.< ..?. - .?- - .. . .. . . , - I i r . c n 1 .I .I , ,-. .z , - . -:>> . - - . . .

-- .L-- -- -- , . . . . - - - . . , , . - , - . -

- . . . . . . - I / , I

" . , . - I i i ' - 8 . 8 . I , I " hlTpS y ! un. - ' , - - -

- I[ 'L 1 13:53 I 1 0 . 2 ~

(hh:mm) I (RR:mm) I I

-7

1 0:50 1 11:OO

-A I 1- -- I I 1 ALTPS bnit 1 I ;7:4C I--

iG:50 --A

'As per information shared by Gujaiat SLDC

Frequeacy Changa": No significant change in iraquency observed

Load 1 Gansration affected: Load loss of 65 MVI (approximately) was reported for 10tmnutes due to tripping. 300 MW generation losses occurred at KLTPS, ALTPS and Renewable Energy sources. (*As per Gujarat SLDC).

Graphical plot: ~ - . - -. . -

Frequency Plot 50 :30 . - - - - - - ~ - ~ - ~ - - - - - - - - - - p - - - - p---p-.----- ~ -

- . ~

, . . . .I ,_

!' - event de tec t~on J - .~ .--- ~ . .~ - . ~

Schematic Network Diagram:

LEGEND

.paMa!r\aJ aq hew SaU!l Jeyyeyy!UeN-eUeJJeyVN AYOzZ 40 s6u!~as lUaJJn3 JaAO 'pal3aUUO3 aJe sl!un 6ulle~aua6 Auew aJayM /ille!3adsa 'sau!~ 40 uMoplnys 6u!r\!6 al!yM lar\al 3als le uayel aq hew a~e3 '(l-Jeyyeyy!UeN-eUI?JlI?yyI?N AYOzZ 40 6u!dd!~l ayl JalJe aA!AJnS Ol alqe IOU SeM pue luals/is 40 /il!l!qe!la~ pue /il!~n3as ayl pampa^ y3!y~ awl1 awes ayl u! lno uayel aJaM Saul1 'SJO~!JJO~ yloq ul 'Saul ewyny pue eueJleyyeN y6no~yl aJe sl!un sdny 40 suo!gen3er\a ayl :syJeurad

dhakate sir

Text Box

Annexure-2.4(v)

dhakate sir

Text Box

Annexure-2.3(i)

dhakate sir

Text Box

Annexure-2.3(ii)

dhakate sir

Text Box

Annexure-2.3(iii)

dhakate sir

Text Box

Annexure-2.3(iv)

dhakate sir

Text Box

Annexure-2.3(v)

MAHARASHTRA STATE ELECTRICITY TRANSMISSION CO. LTD. Testing & Communication Circle, G-8, Laxminagar, Near Baljagat, Nagpur –440 022

ISO – 9001 – 2000 Certified

P – 2228393 O –2221873 R – 2052217 Fax - 0712 – 2234220 E-mail : [email protected] Ref. No : SE/T&C/NGP/Tech/ J1/ 138 Date: 21.03.2012 To, The Chief Engineer, Trans (O & M), MSETCL FAX Corporate Office, Mumbai Sub:- Occurrence at 220 KV S/S Khaparkheda on date 19.03.2012 … analysis thereof 1. Name of the S/S : 220 KV S/S Khaparkheda 2. Name of the feeder / equipment : 220 KV GTR 4 bay 29C Isolator 3. Date & Time of occurrence : Date: 19.03.12 at 20:43 hrs 4. Date & Time of restoration : Date: 20.03.12 at 09:40 hrs (Wardha charged) 5. Details of trippings at Local end : (i.e. at Khaparkheda S/S) S No


Window Indications


1. Busbar protection for 220 KV Transfer bus (i.e. Auxiliary bus) operated and tripped the TBC breaker through its 96 busbar trip relay:

Busbar Protection Operated

Busbar scheme ABB – RADSS with TR and R, T & U flag indications.

i. 220 KV TBC BB Prot optd 96 relay optd. 2. 220 KV GT4 E/F opt. (at PCR

end); LBB operated WI on

GT4 control panel and RTU

DC SCADA IED at GCR end

O/C-E/F relay; LBB relay (B/U + LBB Alstom- KCEG 142), MTR optd.

3. Consequent to operation of the LBB relay of GT4 all breakers connected to 220 KV Main Bus1 including Bus-coupler at Khaparkheda GCR tripped through respective Busbar trip relay 96 as follows:

--- ---

i. 400 KV Koradi ckt BB Prot optd. 96 relay optd. ii. 220 KV Ambazari ckt1 BB Prot optd. 96 relay optd. iii. 220 KV Kanhan ckt2 BB Prot optd 96 relay optd. iv. 220 KV Kaulewada ckt1 BB Prot optd 96 relay optd.

Cont…2

…2…

dhakate sir

Text Box

Annexure-2.4(ii)

v. 220 KV Kalmeshwar ckt BB Prot optd 96 relay optd. vi. 220 KV Wardha ckt BB Prot optd 96 relay optd. vii. 220 KV GT1 MTR Optd 96 relay optd. viii. 220 KV GT3 MTR Optd 96 relay optd. ix. 220 KV GT4 MTR Optd 96 relay optd. x. 40 MVA Stn T/F1 MTR Optd 96 relay optd. xi. 40 MVA Stn T/F3 MTR Optd 96 relay optd. xii. 40 MVA Stn T/F4 MTR Optd 96 relay optd. xiii. 220 KV Bus Coupler MTR Optd 96 relay optd.

6. Details of trippings at Remote ends : Nil

7. Details of Occurrence : i. Outage was availed by construction wing on date 19.03.2012 on 220 KV Main bus2

at 220 KV S/S Khaparkheda for connecting the bus2 side jumpers for the proposed commissioning of two new 220 KV circuits to new Khaparkheda S/S.

ii. For availing this outage all the 9 bays that were connected to 220 KV Bus2 were shifted to 220 KV Bus1 through TBC by the S/S operating staff in the morning session.

iii. After completion of the jumpering work by construction, operation of restoration of normalcy of bays was taken up in hand by S/S operating staff at 17:56 hrs.

iv. Shifting operation for six 220 KV bays (viz: Ambazari2, Kanhan1, Purti, Kaulewada2, GT2 & Stn T/F2) from Bus1 to Bus2 was completed by 20:15 hrs.

v. Shifting operation for 7th bay (i.e. GT4 bay) was taken up in hand by S/S staff at 20:20 hrs. While sequence of operations were underway; at the juncture of tripping of main breaker of GT4 heavy sparking across all the six R, Y & B pole contacts of 29C double break isolator of GT4 bay (at 20:43 hrs) was observed by the switchyard operating staff.

vi. Subsequently all the breakers connected to 220 KV Main Bus1 at Khaparkheda S/S tripped as indicated under item (5) above.

vii. Normalcy of all the bays except GT4 bay was restored by 09:40 hrs on date 20.03.2012. Normalcy of GT4 bay was restored by @16:00 hrs on date 20.03.2012.

viii. The occurrence caused loss of generation of @550 MW of Mahagenco. There were no remote end trippings and the grid was normal.

ix. Single Line Diagram showing the relevant details of tripping is enclosed herewith.

8. Analysis of Occurrence :

i) Main cause of occurrence is the heavy arcing that took place across all the R, Y & B pole contacts (i.e. jaw & blade) of the double break isolator 29C (i.e. TBC side isolator) in GT4 bay during shifting operations. Though after post occurrence, the correct closing and opening operations of 29C isolator of GT-4 bay were confirmed in presence of the CE, EHV CC O & M Zone, Nagpur, SE, EHV O & M Circle, Nagpur, EE,EHV O & M Division, Nagpur and the undersigned, it is felt that there must have been some gap left between jaw and blade of 29C isolator during pre-occurrence shifting operation. This might not have been noticed during night hours. At this instance GT4 was running at @183 MW of power. Thus the current of @500A was initially broken across the imperfectly closed poles of the isolator

Cont…3

…3…

which initiated arcing. The length of arc and the magnitude of flashover current gradually increased and subsequently attained a fault value. The estimated fault current is @10KA.

ii) This heavy arcing fault was in-zone fault for TBC bus (i.e. Auxiliary bus) and thus selective operation of Busbar protection (ABB-RADSS) for transfer bus and subsequent tripping of TBC breaker is IN ORDER..

iii) The occurrence took place at the very instance of hand-tripping of main breaker of GT4 during shifting operation. Hence the GT4 remained connected to Main Bus1 (i.e. 29A isolator was in closed position) also the ‘NIT’ switch remained in ‘INTER’ position.

iv) While other sources connected to the bus-I fed the fault through the TBC, The GT4 directly fed the fault with its own fault contribution (estimated fault contribution by GT4 @1KA). This caused Earth Fault relay of GT4 to operate at PCR end and issued the trip command to TBC & Main breaker. However the fault current did not seize as the Generating Unit-4 was directly feeding the fault. Hence, subsequently its LBB protection operated and tripped all the breakers connected to Bus1. Hence the operation of E/F & LBB protection of GT4 and consequent tripping of all breakers connected to 220 KV Main Bus1 at Khaparkheda is IN ORDER.

v) The sequence of operations for shifting of the GT4 bay was later verified and found OK.

vi) The occurrence has caused due to the initiation of arc across the R, Y & B Poles (i.e. between blades & jaws) of the 29C Isolator of GT4 bay and is attributed to the imperfect closing of the 29C Isolator.

9. Remedial Measures:

i) It is very much essential to ensure proper closing of contacts of Isolators in general

and for heavily loaded bays and during shifting process in particular. Hence it is suggested that the EHV (O&M) Circle, Nagpur should investigate the cause and device the remedial measures thereof.

Enclosed: As above

SUPERINTENDING ENGINEER (T&C)

MSETCL, NAGPUR Copy s.w.r.to: The C.E. EHV CC (O&M) Zone, MSETCL, Nagpur The C.E. SLDC, MSETCL, Kalwa Copy f.w.c. to: The S.E. EHV (O&M) Circle, MSETCL, Nagpur The S.E. ALDC, MSETCL, Ambazari Copy to: The E.E. EHV (O&M) Division, MSETCL, Nagpur The E.E. Testing Dn, MSETCL, Nagpur

T & C Circle, MSETCL, Nagpur

Schematic of the bus arrangement for ocurrence at 220 KV S/S Khaparkheda on dt 19.03.12 at 20:43 hrs

29B29A 29A 29B 29A 29B 29CArc

220 KV Bus1

220 KV Bus2

Aux Bus

29C

ONONOFF

29D

Fault

Notations

P1 P2

B/C TBC

Isolator Close

Isolator Open

Breaker

CTGT4


ISO – 9001 – 2000 Certified

P – 2228393 O –2221873 R – 2052217 Fax - 0712 – 2234220 E-mail : [email protected] Ref.No. SE/T&C/NGP/Tech/ J1/ 167 Date:-07.04.2012 To, The Chief Engineer, Trans (O & M) MSETCL, C.O., FAX Mumbai Sub:- Occurrence at 400 KV S/S Khaparkheda on date 05.04.2012 … analysis thereof 1. Name of the S/S : 400 KV S/S Khaparkheda 2. Name of the feeder / equipment : 400 KV GTR bay (LBB Optd.) 3. Date & Time of occurrence : Date: 05.04.12 at 12:41 hrs 4. Date & Time of restoration : Date: 05.04.12 at 16:00 hrs (Stn 5A charged) 5. Details of trippings at Local end : (i.e. at Khaparkheda S/S) S No


Window / SCADA

Indications


1 LBB relay of GTR bay operated at Mahagenco’s PCR end and tripped following breakers connected to 400 KV Bus1 through respective BB trip relay 96 as under:

---- LBB relay 50Z1 (Areva Micom P123) operated at PCR with trip LED indication. Fault data (Record 25): Ia = 0; Ib=1.25A; Ic=0; Faulted Phase: None; Tme: 12:41:25:22; Dt 05.04.12

i. 400 KV GTR 96 relay optd 96 relay (GTR was OFF) Time: 12:41:44:174 hrs)

ii. 3X167 MVA 400/220 KV ICT1


iii 3X167 MVA 400/220 KV ICT2


iv 400 KV Stn 5A 96 relay optd 96 relay (Time: 12:41:44:174 hrs) v 400 KV Stn 5B 96 relay optd 96 relay (Time: 12:41:44:174 hrs)

6. Details of trippings at Remote ends : Nil

7. Details of Occurrence : i. On date 05.04.2012 at 12:41 hrs all breakers connected to 400 KV Bus1 (one and a

half bus arrangement) tripped at 400 KV GCR Khaparkheda through respective Busbar trip relay 96 as indicated under item (5) above.

ii. On enquiry with the Mahagenco’s 400 KV PCR Khaparkheda it was informed that the LBB relay (Areva Micom P123) of GTR bay for bus1 (50Z1) has operated at their end and has issued the trip command. This GTR bay was however OFF.

iii. Single Line Diagram showing the relevant details of tripping is enclosed herewith. Cont…2

dhakate sir

Text Box

Annexure-2.4(iii)

…2… 8. Analysis of Occurrence :

i) Tripping of all breakers connected to 400 KV Bus-1 through respective 96 BB trip relay consequent to receipt of LBB command from GTR bay of Mahagenco’s PCR end is IN ORDER.

ii) The operation of LBB relay of GTR bay for Bus1 at PCR end of Mahagenco was not rational as the GTR was already OFF and no testing activity that can cause the operation was in progress at GCR end and reportedly at PCR end also. The LBB relay is under the purview of Mahagenco.

iii) During visit of the MSETCL’s testing team to Mahagenco’s Khaparkheda PCR on date 06.04.12 it was informed by Mahagenco that the pre-synchronisation trials of the GTR bay were in progress and the relay operated at the instance of switching OFF / ON the auxiliary dc to the Control & Relay panel. This trial was a part of the routine test. However at the instance of switching of auxiliary supply, the ‘any trip’ pulse from MTR (Master Trip Relay) was active to the LBB relay as the MTR was not resetted.

iv) Though the ‘any trip’ pulse to the LBB relay was set ‘high’ due to active MTR command, the LBB relay should not have operated as GTR was OFF and carrying no current. The current magnitude (I<) pulse should have kept the relay in RESETTED mode. However the LBB relay operated and extended the tripping command.

v) The matter of unwarranted operation of the LBB relay has been taken up T.O. (TCC MSETCL Nagpur) with Mahagenco vide lr. No. Lr. No J1/166 dated 07.04.12 and with M/S Areva vide letter No 162 dated 07.04.12. Comments / reply from both the agencies in this regards is awaited. No specific comment as regards unwarranted operation of LBB relay was made by Mahagenco during our visit to PCR.

vi) The numerical busbar scheme Sifang CSC 150 is provided at 400 KV Khaparkheda GCR. The in-built LBB function of this relay is used for LBB protection for all the bays except GTR. As the control of GTR bay is with Mahagenco, the LBB relay for this bay is also under the purview of Mahagenco and the LBB command for GTR is externally connected to the trip bus of busbar scheme.

vii) As the one and a half breaker bus arrangement is provided at GCR, the breakers connected to Bus-1 & Bus-2 are clearly identified; hence isolator interlock was not probably felt essential for such identification and is not provided in the present scheme and the LBB command of GTR is therefore directly connected to the trip bus without such interlock.

viii) The isolator is not necessary for bus identification but it is felt that the same is necessary for prevention of the undesired extension of LBB command from GTR when it is OFF. The matter for review of the protection scheme for introduction of such Breaker or Isolator interlock is also taken up with M/S Easun Reyrolle Ltd by T.O. vide letter no. J1/163 dated 07.04.12 and the reply from M/S ERL is awaited.

ix) The Sequence of Events (SOE) of various trippings were logged on the SCADA at GCR Khaparkheda but it did not log the event of LBB operation of GTR bay. During the process of investigation during our visit to Mahagenco’s PCR the corresponding wire was found detached from the lug and also the wire was found connected at wrong terminal. The same is now corrected by Mahagenco.

Cont…3

…3… x) As the one and a half breaker bus arrangement is provided at 400 KV GCR

Khaparkheda, the tripping of breakers connected 400 KV Bus-1 consequent to operation of LBB did not cause any interruption of supply. The GTR was already OFF and other bays were being fed through respective Tie breaker / Main breaker.

xi) Normalcy of supply was restored as under:

9. Remedial Measures: i) The cause of unwarranted operation of the LBB relay (Areva Micom P123) of GTR

reportedly during switching operation of auxiliary DC need to be investigated by Mahagenco and preventive measures need to be implemented to avoid recurrence. The matter is already taken up with Mahagenco by T.O.

ii) To avoid any possibility of operation of numerical LBB relay during process of its

booting, it needs to be ensured by Mahagenco that the MTR command is resetted.

iii) Suitable Isolator / Breaker Interlock need to be introduced in the trip logic of LBB / Busbar scheme by MSETCL to avoid unwarranted extension of LBB command during OFF condition of GTR bay. The matter is already taken up with M/S ERL by T.O.

Enclosed: As above

SUPERINTENDING ENGINEER (T&C)

MSETCL, NAGPUR Copy s.w.r.to: The Member Secretary WRPC, Mumbai The C.E. EHV CC (O&M) Zone, MSETCL, Nagpur The C.E. SLDC, MSETCL, Kalwa Copy f.w.c. to: The S.E. EHV (O&M) Circle, MSETCL, Nagpur The S.E. ALDC, MSETCL, Ambazari Copy to: The E.E. 400 KV R S (O&M) Division, MSETCL, Khaparkheda The E.E. Testing Dn, MSETCL, Nagpur The Dy.E.E. 400 KV Testing Unit, MSETCL, Khaparkheda

S N

Name of the equipment / Feeder

Time of Restoration dt 05.04.12 (hh:mm)

1 ICT1 Tie 14:24 2 ICT2 Tie 14:25 3 Stn 5B 14:31 4 Stn 5A 16:00

T & C Circle, MSETCL, NagpurSingle Line Diagram showing the details of trippings at 400 KV S/S Khaparkheda on date 05.04.2012 at 12:41 hrs.

Notations

TR

400 KV Bus1

OFF

Stn 5B

TR

Stn 5AGTR

96 96

LBB of GTR bay optd. at Mahagenco

Isolator Close

Isolator Open

Breaker closed

CT

Chandrapur

ON

ON

400 KV Bus2

OFF ON

ON

Koradi

TR

ON

TR

ON

ICT1ICT2

96 96


P – 2228393 O –2221873 R – 2227311 Fax - 0712 – 2234220 E-mail : [email protected]

Ref.No. SE/T&C/NGP/Tech/ J1/ 236 Date:- 15.05.2012 To, The Chief Engineer Trans (O&M) C.O, MSETCL, FAX/Email Mumbai Sub:- Occurrence at 220 KV S/S Warora on date 13.05.2012….. Analysis thereof

1. Name of the Substation : 220 KV S/S Warora 2. Name of the Feeder / Equipment : 220 KV WPCL Bus Section (R-ph CT Burst) 3. Date & time of occurrence : 13.05.2012 at 08:58 Hrs 4. Date & time of restoration : 14.05.2012 at 10:33 Hrs 5. Details of trippings :

A) At local end : ( i.e. at Warora S/S)

S No


Window Indications


1 220 KV Bus bar Protection (REB 500 ABB Make) of 220 KV WPCL bus operated and tripped following breakers through respective B/B trip relay 96 including bus sectionalizer breaker:

a 220 KV WPCL Ckt-1 nil 96 BB trip relay b 220 KV WPCL Ckt-2 nil 96 BB trip relay

B) Details of trippings at Remote ends :

S No

Name of S/S Name of the feeder


1 220 KV GCR Chandrapur

220 KV Warora Distance protection trip

Dist Zone-2, R-Y-N, XTF=40.6 KM, 86

2 220 KV Wani 220 KV Warora Distance protection optd.

Dist Zone-2 R-Y,86

3 220 KV Wardha 220 KV Warora Distance protection optd.

Dist Zone-2, R-Y-N, XTF=73 KM,86

4 220KV Hinganghat 220 KV Warora Distance protection optd.

Dist Zone-2 R-Y,XTF=48.76 KM,86

dhakate sir

Text Box

Annexure-2.4(iv)

..2..

6. Details of occurrence :

1. On date 13.05.2012 at 08:58 hrs, bursting sound was heard from the switch yard of 220 KV S/S Warora, followed by total a. c. failure at this S/S

2. On Yard inspection ‘R’ ph CT (Make: SCT Gaziabad, Sr. no.: 2009/1766, Mfg year: 2009) of 220 KV WPCL Bus-sectionalizer found to have burst. The failure caused damage to R-ph pole of Siemens make bus-sectionalizer breaker and R-ph insulator of incoming side and outgoing side isolators and carbonisation of adjoining Y-ph CT.

3. In the control room, 220 KV Bus bar Protection scheme (ABB - REB 500) provided for 220 KV WPCL bus found to have operated alongwith the newly commissioned 220 KV Bus bar Protection scheme (Make: NR-RCS 915 ) provided on 220 KV old Warora bus which was kept on alarm mode as indicated under item 5(A) above.

4. Local end tripping of 220 KV WPCL Ckt-I & II are indicated under item 5(A) above; however remote end trippings occurred as indicated under item 5 (B) above

5. The normalcy of supply restored as under :

6. Single line diagram showing the details of tripping is enclosed herewith for reference. Contd…. …3…

S. No.

Name of Sub-Station

Name of Feeder Time of restoration

Duration of Interruption

LBT (MW)

E/I

1 220 KV Warora 220 KV GCR Chandrapur 09:36 Hrs 0:38 Hrs 17 E 2 220 KV Hinganghat 09:56 Hrs 0:58 Hrs 173 E 3 220 KV Wardha 09:55 Hrs 0:57 Hrs 187 E 4 220 KV Wani 09:42 Hrs 0:44 Hrs 8 E 5 220 KV RLY TSS-I No-load - - 6 220 KV RLY TSS-II 09:36 Hrs 0:38 Hrs 2 E 7 220 KV WPCL Ckt-1 10:33 Hrs on

dt.14.05.2012 25:35 Hrs 218 I

220 KV WPCL Ckt-2 09:42 Hrs on dt.14.05.2012

24:44 Hrs 218 I

8 220/66 KV 50 MVA T/F-I 09:44 Hrs 0:46 Hrs

43

E 9 220/66 KV 50 MVA T/F-II 09:44 Hrs 0:46 Hrs E 10 220/33 KV 25 MVA T/F-I No-load E 11 220/33 KV 50 MVA T/F-II 09:41 Hrs 0:43 Hrs -

7. Analysis of occurrence : :

1. 220 KV WPCL Ckt-1 & 2 is commissioned at 220 KV S/S Warora during the year 2010 for connecting 4 x 135 MW proposed generation of M/S Wardha Power Co. Ltd (WPCL). Presently 2 x 135 MW generation of M/S WPCL is connected to our Warora bus through 220 KV WPCL Ckt-1 & 2. 2. The work of extension of existing 220 KV bus in the extended section of switchyard, providing of bus-section breaker and allied work of providing switchgear, protection and SCADA etc was carried out by M/S WPCL on turnkey basis. 3. On date 13.05.2012, at 08:58 Hrs the R-ph CT of 220 KV Bus-sectionalizer burst which created bus fault in WPCL bus and consequently 220 KV Bus bar Protection (ABB-REB 500) of 220 KV WPCL bus operated and tripped 220 KV WPCL Ckt-I & II breakers through respective B/B trip relay 96 including Bus-sectionalizer breaker at Warora end is IN ORDER. 4.Remote end indication at Chandrapur, Wani, Wardha, Hinganghat indicate the involvement of R & Y phases in the fault, indicating that the smoke of the burst R-ph CT must have created a bus fault w. r. to Y phases. This fault was being fed from existing 220 KV Warora bus. The Newly commissioned numerical 220 KV Bus bar protection scheme (RCS 915 Make-NR) provided for 220 KV old Warora bus operated but since the same was kept on alarm mode so as to confirm its stability on through fault, no tripping at local end at Warora S/S occurred. Thus 220 KV bus fault on 220 KV old Warora bus caused all the sources to trip at their respective end on distance zone-2 (R & Y phases). 5. Tripping of all sources at remote end caused total a.c. failure at 220 KV S/S Warora. The occurrence caused loss of generation @436 MW of M/S WPCL. Also the load of Warora Railway TSS of @ 2 MW and local load of @ 43 MW was affected. The load of @ 385 MW of Hinganghat, Wardha, GCR Chandrapur and Wani feeders was thrown off to other lines in the grid. The 220 KV grid however remained stable. 6. The Normalcy of supply was restored on the same date at @ 09:36 hrs (220 KV GCR Chandrapur Ckt Charged) while Bus-sectionalizer breaker charged on next day (i.e. on dt.14.05.2012) @ 09:35 Hrs after replacing R, Y & B ph CTs of bus sectionalizer having Sr.no.2009/1767, 2009/1768, 2009/1769 respectively (Make: SCT, Gaziabad) available with M/S WPCL 220 KV Bus-coupler and WPCL ckt 1 &2 was restored @ 10:33Hrs on dt.14.05.2012 The R-ph pole replaced with R-ph pole of bus coupler breaker. The damaged R-ph isolators were replaced with isolators from bus-coupler.

8. Remedial Measures :

1. M/S WPCL needs to take up the matter with manufactures regarding frequent premature

failure of SCT Gaziabad make CTs at 220 KV Warora S/S and to replace there CTs, PTs on topmost priority in order to avoid such recurrences. Till such time; M/S WPCL to keep close monitoring of SCT Make CTs and PTs by conducting C and Tan delta test.

Contd….

…..4…..

2. The newly commissioned 220 KV Bus bar protection scheme (RCS 915 Make-NR) which was kept on alarm mode to confirm its stability on through fault is now kept on trip mode.

Encl :- As above

Superintending Engineer T& C Circle, MSETCL, NAGPUR.

Copy s.w.r.to: 1) The C.E. EHV CC (O&M) Zone, MSETCL, Nagpur 2) The C.E.L.D, MSETCL, Kalwa Copy f.w.c. to: 1) The S.E. EHV (O&M) Circle, MSETCL, Chandrapur 2) The S.E. L.D, Ambazari, MSETCL, Nagpur 3) M/S. Wardha Power Co. Ltd. B-2, NIDC, Warora Growth Centre, FAX: 07176 285125 Warora 442902 Dist (Chandrapur) ……With request to implement action as suggested in remedial measures. Copy to: 1) The E.E. EHV O & M Division, MSETCL, Ballarshah 2) The E.E. Testing Division, MSETCL, Ballarshah .

MAHARASHTRA STATE ELECTRICITY TRANSMISSION CO. LTD.T & C Circle, Nagpur

Details of Occurrence at 220 KV Warora S/S on dt 13.05.2012 at 08:58 Hrs

220 KV GCR Chandrapur

220 KV Wardha 220 KV Hinganghat220 KV Wani 220 KV Rly

TSS-I220 KV Rly TSS-II

Dist Zone-2 R-Y-N XTF=40.6 KM Dist Zone-2

R-Y-N XTF=73 KM

Dist Zone-2 R-Y XTF=48.76 KM

Dist Zone-2 R-Y

R-ph CT burst

NEW BUS

Busbar Scheme ABB-REB-500

Main Bus-II

Main Bus-I96

Note:- Only relevant details shown

25 MVA 220/33 KV T/F-I

50 MVA 220/33 KV T/F-II

Breaker not tripped

Breaker tripped

50 MVA 220/66 KV T/F-I

50 MVA 220/66 KV T/F-II

Bus section

220 KV WPCL

Ckt-2

OLD BUS

NEW BUS

2 x 135 MW

Buscoupler

Ckt-1

Main Bus-I

CB OFF

Isolator closed

96 96

96

MAHARASHTRA STATE ELECTRICITY TRANSMISSION CO. LTD.

Testing & Communication Circle, G8, Laxminagar, Near Baljagat, Nagpur –440 022

P –2228393 O–2221873 R– 2227311 Fax- 0712 – 2234220 E-mail : [email protected] Ref. No. SE/T&C/NGP/Tech/ J-1/ 314 Date:- 25.06.2012 To The Chief Engineer Trans (O&M) C.O, MSETCL, FAX Mumbai

Sub:- Occurrence at 220 KV S/S Butibori on date 19.06.2012 ….. Analysis thereof

1. Name of the Substation : 220 KV S/S Butibori. 2. Name of the Feeder / Equipment : 220 KV Indorama (220 KV LBB Protection operated) 3. Date & time of occurrence : 19.06.2012 at 03:50 hrs 4. Date & time of restoration : 19.06.2012 at 06:42 hrs 5 (A). Details of trippings at Local end :

( i.e. at Butibori S/S) S No

Name of the feeder / equipment


1 LBB Protection of 220 KV Indorama feeder operated and tripped all breakers connected to 220 KV Bus 1, including Bus-coupler, through respective 96 BB trip relays, as follows:

-

2 220 KV Indorama LBB protection optd 2/50Z, 96 3 220 KV Inox i)Pilot wire prot optd.

ii)Pilot wire defective 96

4 220 KV Buscoupler Nil 96 5 50MVA 220/33 KV T/F-3 Nil 96 6 220 KV Koradi Trip relay optd. 96

5 (B) Details of trippings at Remote end : Nil

6. Details of occurrence :

1. On dt.19.06.2012 at 220 KV Butibori S/S all breakers connected to 220 KV Main bus-1 including Bus-coupler tripped through respective 96 BB trip relay as indicated under item 5(A) above.

2. There was no tripping at any other remote end S/Ss. 3. Last maintenance of 220 KV Indorama bay carried on: Dt. 10.04.2011

Contd……

dhakate sir

Text Box

Annexure-2.4(v)

….2…. 4. Restoration of supply was done as given below:-

S. No.

Name of Sub-Station Name of Feeder Time of restoration

LBT (MW)

1 220 KV Butibori 220 KV Bus Coupler 05:16 Hrs - 2 220 KV Butibori 220 KV Indorama feeder 06:17 Hrs 1 3 220 KV Butibori 220 KV INOX 05:24 Hrs 2.5

4 220 KV Butibori 50MVA 220/33 KV T/F-3 06:36 Hrs 12 5 220 KV Butibori 220 KV Koradi 06:42 Hrs 55

5. Single Line Diagram of 220 KV S/S Butibori, showing relevant details of tripping is

enclosed herewith for ready reference. 7. Analysis of occurrence :

1. There was a fault on 11 KV bus at M/S Indorama company emanating from 220 KV Butibori S/S. For this fault, 11/33 KV Tie 4 & 5 T/F tripped on over-current relay at consumer end with fault current @ 1.71 KA and 1.63 KA on 33 KV side in about 232 msec.

2. The matter of operation of LBB protection of 220 KV Indorama feeder was investigated in detail and the problem of contact of trip relay RXMS1 was detected. It was found that the D.C logic of LBB relay on 220 KV Indorama panel at 220 KV Butibori S/S was through via bus bar protection trip relay (96) contact which was found stuck in make condition. The fault current was above the pick up setting of LBB relay . Current setting of LBB relay is 0.8 A sec(CTR-400/1A) that is 320 A primary with 200 msec timer setting. As D.C. logic of the LBB relay was already through and fault current was above pick up setting of LBB relay resulting into operation of LBB protection of 220 KV Indorama feeder. The problem of contact of trip relay RXMS1 was later attended and confirmed that the D.C. logic of LBB relay is not through.

3. It is to note that back up protection of 220 KV Indorama feeder did not operate for the above fault as the fault current was just above the pick up setting of LBB relay and Earth fault relay will take time @0.5Sec to operate. The setting of Back up O/C and E/F relay (Make: EE, Type: CDD) are:

CTR PS TMS O/C R & B 400/1A 100% 0.08 E/F 40% 0.08

4. The total fault current shown at 33 KV level at M/S Indorama end is @3.34KA (Ref: Annexure:2). For this fault, The fault current shown by 220 KV side relay of 220/33 KV T/F at 220 KV Butibori S/S end is @500 A. From this it appears that @500 A fault current is fed from 220 KV bus at 220 KV Butibori S/S. For 500 Amp fault current the time require for E/F relay to operate is calculated as under: 500A/160=3.1 means for 3 times current TOP is 6.302 and TMS setting for E/F is 0.08. Thus time requires to operate E/F relay comes out to be @504 msec. From this it appears that before operation of E/F relay of T/F, the LBB relay of Indorama feeder operated with pick up setting of 320 A primary with 200 msec timer setting.

5. The occurrence caused interruption to EHV consumers M/S Indorama & M/S INOX (Load 1MW and 2.5 MW respectively) and also local 33 KV load of @ 12 MW was affected. The load @ 55 MW on 220 KV Koradi feeder was shared by other feeders and the grid remained stable.

Cont…3

+ …3… 8. Remedial Measures :

1) The operation of LBB protection of 220 KV Indorama feeder is undesirable. In view of this, the D.C. logic of LBB relay of all feeders checked and confirmed that it is not through.

2) The operation of LBB relay of 220 KV Indorama feeder was mainly due to contact stuck up problem of trip relay RXMS1, which activated D.C. logic of the relay. As such the matter is discussed at the SPC meeting dt.20.06.2012 for providing the supervision to the ‘LBB initiated’ command. It is decided in the SPC that the decision to provide ‘LBB initiation supervision’ shall be taken in next SPC after detail discussion.

Encl :-As above

Superintending Engineer

T& C Circle, MSETCL, NAGPUR

Copy s.w.r.to: The C.E. EHV CC (O&M) Zone, MSETCL, Nagpur The C.E. SLDC, MSETCL, Kalwa Copy f.w.c. to: The S.E. EHV (O&M) Circle, MSETCL, Nagpur The S.E. ALDC, MSETCL, Ambazari Copy to: The E.E. EHV (O&M) Division, MSETCL, Nagpur The E.E. Testing Division, MSETCL, Nagpur

MAHARASHTRA STATE ELECTRICITY TRANSMISSION CO. LTD.T & C Circle, Nagpur

Details of Occurrence at 220 KV Butibori S/S at 03:50 Hrs on dt 19.06.2012

Bus-Coupler

50 MVA

220 KV Bus II

220 KV Wardha

96

96

50MVA220/33 KVT/F 3

96

2/50Z,96 220 KV Bus I 96

220 KV Sunvijay

50 MVA

220 KV VIPL Ckt-I

Note : Only relevant details shown.

50 MVA220/33 KV T/F 2

220 KV Inox

220 KV Koradi

220 KV Indorama

96 50 MVA 220/33 KV TF1

100 MVA220/132 KV

ICT

Annexure‐XX

Proposal for additional SPS in NR Power System NRLDC

3. New Proposed SPS

3.1. Schemes for taking care of tripping of multiple transmission lines

a) SPS for contingency due to interruption of import by NR at 400 kV Agra (from WR) During the sc enario of heavy import by NR from W estern Region, sim ultaneous

tripping of 400 kV Agra-Gwalior circuit-I & II or tripping of 400 kV Bina-Gwalior ckt-I & II results in r ush of pow er on pa rallel in terconnections o f NR w ith WR and ER. The contingency can result in heavy ov erloading of network in We stern region (esp ecially in Gujarat) as well as in Eastern region with critically low vo ltage in the large part of ‘NEW’ grid.

The above contingency occurred on 1st July 2010, 07th Dec 2009 and 28 th Nov 2009.

On all these occasions ther e was an in terruption of i mport at 400 kV Agra ( from WR) through 400 kV Agra- Gwalior- ckt-I & II. The contingency resulted in severe l ow voltage throughout the ‘NEW’ grid and had the potential of resulting in cascade failure in large part of NEW grid.

Therefore, an SPS for shedding loads in western UP, Rajasthan, Punj ab & H aryana

area in the event of sudden large reduction of import at 400 kV Agra (from WR) would help in minimizing the im pact of contingency. If t he actual import on the 400 kV Agra Gwalior D/C is more than a certain level, automatic backing down of generation in the WR would also be desirable.

SPS Scheme logic: Case-1

Contingency: Sudden Reduction of im port by NR on 400 k V Agra-Gwalior ckt-I & II b y more than 1000 MW but less than 1500 MW Action 1: Shed loads in Groups C & D in the Northern Region as described in Annex-1. (Load S hedding Sh all b e achieved within 500 ms, including all si gnal propagation/breaker opening time delay)

Case-2 Contingency: Sudden Reduction o f import by NR on 400 kV Agra-Gw alior ckt-I & II by more than or equal to 1500 MW Action 1: Shed Loads in Groups C, D, E & F as described in Annex-1. (Load S hedding Sh all b e achieved within 500 ms, including all si gnal propagation/breaker opening time delay) and Action 2: Automatically b ack do wn 500 MW generation in w estern region in th e shortest possible time.

user

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dhakate sir

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dhakate sir

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Annexure-3.1(ii)

dhakate sir

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Annexure-3.2

Annexure‐3.3

ALARM AND TRIP SETTINGS FOR GENERATORS IN WESTERN REGION

Station Unit Setting Type Time delay Setting Type Time delay

VSTPS 1 to 6 48.5 Hz Alarm 5 SEC7,8 48.5 Hz Alarm 5 SEC7,8 47.8 Hz Trip 1.5 Sec9,10 48.5 HZ Alarm 5 SEC9,10 47.4 Hz Trip 2 Sec

KAPS 1,2 48 Hz Alarm 5 Sec

1,247.6 Hz & Df/dt 48 Hz 0.6 Hz/Sec Islanding 2 Sec 51.0 Hz Alarm 5 Sec

1,2 47.5 Hz Trip 5 SEC1 51.0 Hz Alarm 5 Sec2 51.0 Hz Alarm 10 Sec1 51.5 Hz Trip 20 Sec2 51.5 Hz Trip 10 Sec

KAWAS GPP GTs 47.0 Hz Trip 2.4 SecSTs 47.0 Hz Trip 2.4 Sec

Dahanu TPS 1,2 48.5 Hz Alarm 1 Sec 53.5 Trip 4 Sec1,2 47.0 Hz Trip 4 Sec

NSPCL 1,2 48.5 Hz Alarm 2.5 Sec 50.5 Hz Alarm 2.5 Sec1,2 47.4 Hz Trip 2.0 Sec 51.4 Hz Trip 2.0 Sec

KORBA(W) 48.8 Hz Alarm 51 Hz Alarm

Low Frequency High Frequency

AlarmTIME

DELAYTrippin

gTIME

DELAY AlarmTIME

DELAYTrippin

gTIME

DELAY1 48.5 1 Sec 47.5 3 Sec 51.5 1 sec2 48.5 1 Sec 47.5 4 Sec 51.5 1 sec3 48.5 1 Sec 47.5 3 Sec 51.5 1 sec4 48.5 1 Sec 47.5 3.5 Sec 51.5 1 sec5 48.5 1 Sec 47.5 4 Sec 51.5 1 sec1 48.5 1 Sec 47.5 3.0 sec 51.5 1 sec2 48.5 1 Sec 47.5 3.0 sec 51.5 1 sec3 48.5 1 Sec 47.5 3.0 sec 51.5 1 sec4 48.5 1 Sec 47.5 3.0 sec 51.5 1 sec5 48.5 1 Sec 47.5 3.0 sec 51.5 1 sec1 48.5 1 Sec 47.4 4 Sec 51.5 1 sec2 48.5 1 Sec 47.4 3.5 Sec 51.5 1 sec3 48.5 1 Sec 47.4 3 Sec 51.5 1 sec4 48.5 1 Sec 47.4 4 Sec 51.5 1 sec5 48.5 1 Sec 47.4 3.5 Sec 51.5 1 sec6 48.5 1 Sec 47.4 3 Sec 51.5 1 sec7 48.5 1 Sec 47.4 5 Sec 51.5 1 sec1 48.5 1 Sec 47.5 5 Sec 51.5 1 sec2 48.5 1 Sec 47.5 5 Sec 51.5 1 sec

47.4 3 Sec47.3 Inst.

4 48.5 1 Sec 47.5 3 Sec 51.5 1 sec

48.50.15 Sec

480.15 Sec

2 47.90.15 Sec 47.4 5 Sec 51.6 1 Sec

CCPP-I GTG 48.5 1 Sec 47.5 1 Sec 52.5 10 Sec

CCPP-I STG 48.5 1 Sec 47.5 1 Sec 52.5 8 Sec

CCPP-II GT 48.5 1 Sec 47.5 1 Sec 52.5 10 Sec

CCPP-II STG 48.5 1 Sec 47.5 1 Sec 52.5 8 Sec

CCPP-I GT-1 48.5 1 Sec 47 3 Sec



CCPP-I STG 48.5 1 Sec 47 3 Sec

DHUVARAN GBPS

UTRAN

1 sec

SIKKA TPS

1 47.4

6.0 Sec

52

WANAKBORI TPS

KLTPS 3 48 Inst.

GANDHINAGAR TPS

Power station Unit

UNDER FREQ. HZ OVER FREQ. HZ

UKAI TPS

CCPP-II GT 48.5

0.15 Sec 46.95

0.15 Sec

45.750.15 Sec

CCPP-IISTG 48.5

0.15 Sec 46.95

0.15 Sec

45.750.15 Sec

123 48 1.5 Sec 47.5 5 Sec4 48 1.5 Sec 47.5 5 Sec

RBPH-1 48 2 Sec 47.5 1 Sec 52.5 3 Sec

RBPH-2 48 2 Sec 47.5 1 Sec 52.5 3 Sec

RBPH-3 48 2 Sec 47.5 1 Sec 52.5 3 Sec

RBPH-4 48 2 Sec 47.5 1 Sec 52.5 3 Sec

RBPH-5 48 2 Sec 47.5 1 Sec 52.5 3 Sec

RBPH-6 48 2 Sec 47.5 1 Sec 52.5 3 SecCHPH 1-

5

KADANA (HYDRO)

Generation

SSNL (HYDRO)

Generation

Relays are not provided

GBPS

Documents

115pcm agenda final - wrpc.gov.in · Korba(E) Unit-3,4,5 (50 MW each) Overspeed/turbine trip BALCO Unit-1 &2 Over frequency . 2 Agenda for 115th Protection Committee of WRPC DSPM