SOUTHERN REGIONAL POWER COMMITTEE BANGALORE … · 7th April in the Conference Hall of Southern...

SOUTHERN REGIONAL POWER COMMITTEE

BANGALORE

MINUTES OF THE 11th MEETING OF PROTECTION SUB- COMMITTEE OF SRPC HELD ON 06.04.2011 & 07.04.2011

1.INTRODUCTION

1.1 The 11th meeting of Protection Sub-Committee was held on 06th &

7th April in the Conference Hall of Southern Regional Power

Committee, Bangalore. Working group Meeting of PCC to discuss

and analyze grid disturbances held on 06.04.2011 and other

protection related issues were discussed on 07.04.2011.The list of

participants for the working group meeting is enclosed as

Annexure-I.

1.2 Shri S.D. Taksande, Member Secretary I/c, SRPC welcomed the

participants to the working Group meeting of the Protection Sub-

Committee. He briefly informed the forum regarding introduction of

working group meetings in PCC which will discuss grid

disturbances in the system. He briefed the forum regarding the Sub

Group meeting held on 24.02.2011 to discuss SPS at Nagjhari,

Varahi , UPCL and Protection issues of Kaiga. He highlighted the

decisions taken in the Sub group meeting to the PCC forum. It was

noted that there was no participation from AP, TNEB and

Puduchery in the Working Group Meeting.

1.3 MS (I/c) further pointed out that Even though several

reminders were sent to give the Grid incidences report in a timely manner the response from constituents is not encouraging. It was requested that all the constituents may send the System Disturbance/Occurrence/Incident Reports for monitoring and Event analysis to SRLDC and SRPC as per IEGC 5.9.4 (b) (as specified by IEGC 5.9.6 (c) format )at the earliest to make the PCC meeting discussions to be effective and fruitful.

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2. CONFIRMATION OF THE MINUTES OF THE 10TH PROTECTION SUB-COMMITTEE MEETING HELD ON 27th OCTOBER 2010

The Minutes of the 10th Protection Sub-Committee Meeting were

confirmed since no comments were received from any of the constituents.

3. SYSTEM DISTURBANCES

3.1 Partial Black out of Karnataka System on 18.03.2011 Member Secretary (I/C) said that the issue of Partial black Out of

Karnataka System on 18.03.2011 should be taken as a priority agenda to

understand/analyze the disturbance in detail to identify remedial action

and to prevent future occurrences.

Representatives from KPTCL briefed the incident on 18.03.2011 in

Karnataka system as follows.

Pre-fault Scenario: at 13-20Hrs.

1) Load flow from Guttur to Hiriyur: 400 kV Line-1 - 455 MW 400 kV Line-2 - 455 MW Total - 910 MW

2) Load handled by 400 kV Guttur bus:

Kaiga-1 - 211 MW Kaiga-2 - 211 MW Narendra-1 - 157 MW Narendra-2 - 169 MW JSW - 417 MW Guddadahally - 11 MW Total - 1176 MW

3) Load handled by 400 kV Nelamangala station:

Talaguppa (Shantigrama) - 150 MW Hiriyur-1 - 362 MW Hiriyur-2 - 332 MW Gooty - 450 MW

2

Hoody - 188 MW Total -1482 MW

4) Load handled by 400 kV Hoody station:

Gooty - 302 MW Kolar-1 - 320 MW Kolar-2 - 318 MW Total - 940 MW

5) RTPS 400 kV station:

G1 - 209 MW G2 - 168 MW G3 - 179 MW G4 - 167 MW BTPS - 382 MW Total - 1105 MW

At 13-23 Hrs: Due to a high resistance fault on Y-phase of line-1 between Guttur

and Hiriyur, MICOM P442 relay used as Main-1 and Main-2 picked up on

distance relay and Y-phase link tripped. (Distance 64 kms from Guttur, total

length of the line is 115 kms).

Current carried by this faulty line was transferred to Y-phase of line-2 and

consequently EFR feature enabled in Main-1 sensed the fault and resulted in

tripping of line-2.

In line-1 auto Reclosure operated, but due to persistence of fault in line-1,

breaker cleared the fault by three pole tripping.

Thus the power flow of about 910 MW flowing from Guttur to Hiriyur &

to Nelamangala got affected and Nelamangala started drawing power mainly

from Sharavathy via 400 kV Talaguppa-Shantigrama-Nelamangala and 220 kV 4

number lines between MRS Shimoga-Nelamangala. The power flow is as

follows.

1) Load flow from Guttur to Hiriyur: 400 kV Line-1 - 0 (455) MW 400 kV Line-2 - 0 (455) MW Total - 0 (910) MW

2) Load handled by 400 kV Guttur bus:

Kaiga-1 - 178 (211) MW Kaiga-2 - 178 (211) MW Narendra-1 - 118 (157) MW Narendra-2 - 118 (157) MW

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JSW - 198 (417) MW Guddadahally - 225(E) [11(I)] MW Total - 790 (1176) MW

3) Load handled by 400 kV Nelamangala station:

Talaguppa (Shantigrama) - 267 (150) MW Hiriyur-1 - 7 (362) MW Hiriyur-2 - 7 (362) MW Gooty - 650 (450) MW Hoody - 325 (188) MW Total - 1256 (1482) MW

4) Load handled by 400 kV Hoody station:

Gooty - 421 (302) MW Kolar-1 - 335 (320) MW Kolar-2 - 333 (318) MW Total - 1089 (940) MW

5) RTPS 400 kV station:

G1 - 210 (209) MW G2 - 168 (168) MW G3 - 181 (179) MW G4 - 167 (167) MW BTPS - 569 (382) MW Total - 1295 (1105) MW

6) 220 kV MRS Shimoga:

Kadur - 207 (169) MW (E) KB Cross - 163 (124) MW (E) Antharsanahally - 141 (105) MW (E) Hassan - 132 (106) MW (E) Davanagere - 100 (26) MW (I) Honnali - 52 (17) MW (I/E)

7) Sharavathy:

MRS Shimoga-1 - 158 (140) MW




Talaguppa-1 - 151 (113) MW

Talaguppa-2 - 150 (112) MW

Shiralkoppa - 85(E) (121(E)) MW

Sirsi-1 -79 (23) MW (I)

Sirsi-2 - 80 (23) MW (I)

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At 13-44 Hrs: Due to increased load flow on Kadur and KB Cross lines at

MRS Shimoga, the 2 lines tripped on OCR at MRS Shimoga. Simultaneously

400 kV Shantigrama-Nelamangala line tripped at Shantigrama on power

swing. Due to these trippings, 7 units at Sharavathy and lone unit at UPCL

tripped.

At 13-44 Hrs: At the same time 400 kV BTPS-RTPS line which was

handling about 617 MW tripped at RTPS. It is reported by RTPS staff that the

fault is C-phase to ground. Due to this 220 kV Lingapur-Kustagi line tripped

on PSD.

Consequently, the power flow reduced in the following lines of Kaiga

complex.

Kaiga - Guttur-1 : 20 (164) MW

Kaiga – Guttu-2 : 20 (164) MW

Kaiga – Narendra-1 : 68 (127) MW

Kaiga – Narendra-2 : 72 (131) MW

Narendra - Guttur-1 : 26 (105) MW

Narendra - Guttur-2 : 26 (105) MW

At 13-48 Hrs: Also 5 units at Nagjhari tripped due to over excitation.

At 13-55 Hrs: BTPS unit tripped on over excitation.

At 13-56 Hrs:

1) The Hubli-Bidnal line tripped at Bidnal on distance protection.

2) Also other 2 units at Sharavathy and 2 units at Varahi tripped causing bus

shutdown at Sharavathy, MRS Shimoga, Varahi, Kemar and other

stations. The 220 kV lines at Sharavathy hand tripped since no units were

running.

At 14-01 Hrs: Due to substantial decrease in demand and minimal power

flow in 400kV lines between Kaiga-Guttur, Narendra-Guttur, JSW-Guttur,

and Guddadahally- Guttur. These lines tripped on over voltage.

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DELIBERATIONS IN THE MEETING

• During the deliberations it was observed that complete data was

not available and analysis of occurrence needed further therefore it

was decided to convene a Sub group meeting to discuss the

incident in detail before the TCC/SRPC.

• Member Secretary (I/c) requested SRLDC,KPTCL,PGCIL, KPCL

and Kaiga to nominate one member to the Sub Group to discuss

the incident .

• Complete data such as relay indications, DR’s, EL and SOE’s

should be made available before the meeting.

• It was also decided to discuss elaborately the Partial black out in

the sub group meeting.

3.2 The system Disturbances / occurrences in the Southern region

showing Major Generation loss, Details of Major Incidences are given in

Annexure- II as given by SRLDC vide Lr. No GM/SRLDC/11 dt.

07.02.2011 (Annexure III).

3.3 Major Generation Losses

3.3.1) Generation Loss at Idukki and LP all units

The representative from KSEB explained the occurrence and

analyzed as follows. On 21.12.2010 at 18:33 Hrs. 220 kV Idukki-Lower

Periyar tripped and reclosed at Idukki end but tripped at LP end on Earth

fault. At 18:34 220 kV Idukki-LP-2 feeder also tripped. Due to this other

feeders become overloaded and tripped. Two units at Idukki and all units

at LP tripped and the loads of all other units at Idukki were thrown off. Due

to this disturbance there was a generation loss of 800 MW and 500 MW of

Load was affected. The frequency dropped from 49.68 Hz to 49.18 Hz.

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ANALYSIS OF INCIDENCE:

The 220 KV Idukki- Kalamassery No 1 feeder was under shutdown. At

18.34hrs, 220 KV Idukki-Lower Periyar No1 feeders got tripped and

reclosed at Idukki end. At Lower Periyar end, the feeder got tripped on

Directional Earth Fault Relay and one back up relay. The distance relay

was set with quadrilateral characteristics for ground faults. This RAZFE of

ABB relay had a problem that if the fault resistance goes beyond a certain

value, the distance relay will not operate. This fault may be of high

resistance in nature, By the time of tripping of Idukki-Lower Periyar No.1

feeder, 220 kV Idukki-Lower Periyar No.2 feeder became overloaded and

one jumper connection in one phase was opened. As a result of this, at

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18:35 hrs. 220 kV Idukki-Lower Periyar No.2 feeder also got tripped and

reclosed at Idukki end. The jumper was opened and continued fault

towards LP side but opened towards Idukki side. Therefore IDLP2 feeder

was not reclosed at LP end. The tripping of Idukki LP No.2 feeder was

due to the arcing to ground fault during jumper opening. As the result of

the above trippings of both feeders, heavy over loading in 220 kV Idukki-

Kalamassery No.2 feeder, 220 kV Idukki New Pallom feeder and 220 kV

Idukki-Udumalpet feeder were tripped due to overloading. During the

replay of the incident in next day, KSEB could see exporting of power and

overloading of Idukki-Udumalpet and Idukki- New Pallom feeders after

opening of Idukki Lower Periyar 1 and 2 feeders.

At Lower Periyar power house, there were 3 generators. All the

generators were got tripped on transformer over current protection

operation due to overloading to feed to northern Kerala.

At Idukki Power House, all power out going paths were lost in this

way, and units began to run in no load condition. Meanwhile Unit No.6

tripped due to over speed as a result of problem related with governor

panel.

From KSEB it is understood that the Idukki-Lower Periyar lines

were in heavily loaded condition and its jumpers in the feeders No 2 were

weakened. As a result of the weakening of jumpers of feeder No.2, some

jumpers in feeder No.1 also would have been weakened and loosened

and which would have produced arcing. At the same time, the current in

one of the phase of feeder No.1 would have been increased due to high

resistance in feeder No.2 of the same phase. The arcing fault in feeder

No.1 may have sensed by Idukki end relay and not by LP end distance

relay. When the breaker of feeder No.1 at Idukki end got opened, the

arcing would have quenched within the dead time of the Idukki end

breaker. This is due to high resistance fault. Due to nearly doubled

current in one phase of feeder No.1 due to high resistance in feeder No.2

loose jumper, feeder No.1 tripped due to directional earth fault which was

unnecessary.

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The Idukki end of the feeder No. 1 would have not reclosed

successfully if there was fault persisting. Due to phase error of CVTs,

some zero sequence voltages are created which is sufficient to mal

operate the Directional Earth Fault Relay. The solution was to replace

such directional earth fault relays with the ones of which the minimum

zero sequence voltage required for operation can be varied. KSEB

informed that they were observing the performance of directional earth

fault relay whether such mal operation repeats or not.


• After deliberation by members committee observed that on 24.03.2011,

IDLP1 feeder tripped and reclosed at LP end which showed that the

distance relay at LP end is functioning well.

• Threshold limit of pick up voltage of relay is to be observed and settings to

be decided accordingly..

• The forum recommended that the performance of CVT at LP also to be

observed .

• The PCC forum requested KSEB to expedite replacement of Static relays

with Numerical relays at the earliest and the relay set points to be

examined and coordinated.

3.3.2) Generation Loss at Nagjheri, Kadra and Kodasalli all units

Representative from KPTCL explained and analyzed the

occurrence as follows. On 22.12.2010 at 15:41 hrs. 220 kV Ambewadi-

Narendra-2 tripped on distance protection. Line-1 flow increased to 256

MW, the bus sectionaliser-2 breaker at PGCIL Narendra tripped.

220 kV Kadra-Kaiga tripped on over current relay, this resulted further

increase of flow on 220 kV Ambewadi-Narendra-1.

At the same time T/F at Hubli and Bidnal tripped resulting in load

throw off. Due to this the generating units at Nagjheri (5 units), Kadra (2

units), Kodasalli (2 units) tripped on over flux and over speed relays.

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Due to this disturbance there was a generation loss of 800 MW.

The frequency dropped from 49.82 Hz to 49.43 Hz.


System disturbance occurred on 22-12-2010 at 15-40 Hrs leading

to tripping of units at Nagjheri, Kadra and Kodasahalli generating stations.

Around 850 MW from 3 generating stations (9 generators) was affected

due to the above disturbance. The prefault scenario and quantum of

power flow in each line are shown below.

Ambewadi

PondaXeldam 58MW

Supa

121MW118MW

21MW Nagjhari

4 X 150 1 X 135

133MWI

132MWII

Bidnal

Harti

117MW

54MW

117MW

114MW107MW

54MW

172MW

LC

CTR-1600/1A Plug-0.7,

Time-100mSec.

BS1

BS2

Soundatti

Hubli

70MW

82MW

36MW 21MW

KS Halli 3 X 40

LC

315MVA ICTs Narendra

Kadra 3 X 50

114MW

160MW

Kaiga

Incident – I (15:41:26 Hrs) : a) Line-II between Ambewadi and Narendra tripped at both Ambewadi

and Narendra on distance relay MICOM P-437 with CN indication.

Location 39 Kms from Narendra and total line length is 54 Kms.

Line-II load sifted to Line-I and total load on Line-I now is 256 MW.

Consequent to tripping of line-II, bus sectionalizer II breaker at

PGCIL Narendra also tripped. (CTR-1600/1A, Plug-70%, Time-

100mSec.) Time set is too low which was set by PGCIL on 13-12-

2010 which has to be revised to at least 300mSec.

b) Load flow from 160 MW to 183 MW increased between Kadra and

Kaiga.

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c) Load flow from Bidnal towards Harti I & II lines increased from 54

MW to 135 MW.

d) Load flow between Hubli and Narendra Line-I increased from 70

MW to 133 MW and the other line was on LC.

Incident – II (15:42:26 Hrs): a) Line between Kadra and Kaiga tripped on OCR at Kaiga end which

was carrying a load of 183 MW. The line between Kaiga and

Kodasahalli was already on LC.

b) This resulted in power flow reversal between Kadra and

Kodasahalli (124 MW).

c) The power flow on two lines between Kodasahalli and Nagjheri

increased to 101 MW each from 21 MW.

d) Power flow between Ambewadi and Narendra increased to 275

MW from 256 MW and that between Narendra and Haveri

increased to 167 MW each on two lines.

e) Power flow between Hubli and Narendra increased to 158 MW.

f) Power flow between Nagjheri and Hubli increased to 163 MW each

from 114 MW.

g) Power flow between Nagjheri and Bidnal increased to 170 MW

each from 119 MW.

Incident – III (15:44:26 Hrs):

a) Due to increased power flow towards Hubli bus and Bidnal bus

from Nagjheri bus, transformer at Hubli and Bidnal have tripped on

over flux relay. Coincidentally Soundatti line at Bidnal tripped on

distance relay and Harti lines I & II tripped at Harti towards Bidnal

on OCR.

b) It is learnt from the concerned station staff that at Hubli and Bidnal

all other lines were hand tripped.

c) Due to the sudden throw off of load, generating units at Nagjari (5

units), 2 units at Kadra and 2 units at Kodasahalli have tripped on

over flux and over speed relays.

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From the above it may be seen that except for non-availability of

two lines, one between Kodasahalli & Kaiga and another line between

Narendra & Hubli which were under LC there were no system constraints

to cause such a major disturbance. This disturbance could have been

avoided in the presence of a system protection scheme at Nagjheri

complex where in during outage of one line emanating from Nagjheri bus

could trip one unit each so as to keep the grid under stable condition.

DELIBERATIONS IN THE MEETING After discussion committee observed that

• The SPS at Nagjheri complex could have averted the tripping of Units

and recommended KPTCL and KPCL to implement the SPS at

Nagjheri at the earliest.

• KPTCL agreed to implement the SPS within 60 days.

3.4 Details of 400 kV buses becoming dead : NIL

3.5 Details of Major Incidences 3.5.1) 220 KV Lingsugur Bus dead

The representative from KPTCL explained the occurrence as

follows. On 04.11.2010 at 04.48 Hrs 220 kV Lingsugur-RTPS-3,

distance relay acted but breaker not tripped due to R-phase trip coil

problem, which resulted in tripping of all 220 kV feeders from

remote end.

Due to this incident the frequency dropped from 49.85 Hz to

49.77 Hz.

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Sindhanur

Lingapur

BB Wadi Lingasugar RTPS

Kustagi

At 04-48 Hrs: RTPS-3 line tripped on distance relay at Lingasugar station

with following indication.

Distance-70.72 km (Total length is 94 km)

Z2 trip.

The cause for the fault is insulation de-caped at location no.74.

But R-phase limb of circuit breaker did not trip due to trip coil burnt.

Hence incoming lines tripped at the sending end causing bus shutdown at

Lingasugar.

Sl. No.

Station Name Line Name Relay Indication Remarks

1 Shahapur Lingasugar DOCR & DEFR operated --

2 Basavanabagewadi

Lingasugar 1 & 2 --

Since the station was fed from Lingasugar radially (No supply from Almatti), no relay acted.

3 Kustagi Lingasugar DOCR & DEFR operated --

4 Sindhanur Lingasugar DOCR & DEFR operated --

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• PCC requested KPTCL to provide bus bar protection at Lingsugur

and LBB to be set at 250 msec.

• KPTCL had not furnished the reports along with the Event logger at

Raichur (KPCL) end, KPTCL informed they will revert back with the

reports.

• KPTCL agreed to provide bus bar protection at Lingsugur in

sequence and the B/B protection requirement would be forwarded

to the concerned division.

• KPTCL also informed that the LBB protection will be made

operational.

3.5.2)Tripping of 400 KV Lines from Ramagundam

Representative from NTPC explained the trippings as

follows. On 05.11.2010 at 22:55 hrs. 400 kV RGM-N’sagar Line– I

taken out to contain over voltage. At 23:37 hrs. 400 kV RGM-

Malkaram Line tripped on direct trip from Malkaram and 400 kV

Gajwel-HYD Line tripped on over voltage. NTPC RGM total power

was evacuated through 400 kV RGM-HYD-Line 3 and 400 kV

RGM-N’sagar-Line II.

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• Committee observed that this is not the grid disturbance individual

incidences leading to one another.

• NTPC representative expressed concern that only two lines were

available for Ramagundam evacuation and over voltage was

persisting.

• GM,SRLDC enquired about the MVAR absorption .It was pointed

that up to the desired level of MVAR absorption by NTPC should

have helped in maintaining the voltage level in Ramagundam.

• NTPC told that they will revert back to PCC with detail and see that

MVAR absorption by units is ensured as per capability curve..

3.5.3) 220 KV Areakode SS Dead

The representative from KSEB explained the occurrence as follows.

On 10.11.2010 at 12:59 hrs. all 220 kV feeders from Areakode SS

dead due to heavy lightening in the area.

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There were three lines from Madakkathara (Thrissur) substation to

Areakode substation. One is from Madakkathara to Areakode, Second

one is from Madakkathara to Shornur and then from Shornur to Areakode.

Third one is from Madakkathara to Malapparamba and then from

Malapparamba to Areakode. Besides there are Areakode-Vadakara

feeder, Areakode-Kaniampetta feeder, Areakode-Nallalm 1 & 2 feeders

and Areakode-Kanjirode feeder.

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Normally, Kaniampetta substation is fed from Kadakola supply. Via

a dedicated bus in Areakode substation, Vadakara substation and

Kanjirode substation is also fed from Kadakola supply. Thus northern

Kerala is fed from Kadakola supply in this way.

On 10.11.2011, Kadakola-Kaniampetta line was under permit work

from 07.53 hrs to 13.37 hrs and therefore Madakkathara supply was

extended to Kaniampetta, Vadakara, Kanjirode and rest of northern

Kerala through the bus coupler closed at Areakode substation.

At 12.11 hrs, 220 kV Areakode – Shornur feeder was tripped due

to conductor snapping. Thus one input to Areakode was failed. At 12.59

hrs, 220 kV Madakkathara-Malapparamba feeder tripped with C phase to

ground zone 1 on Malapparamba end and C phase to ground zone 2 at

Madakkathara end. 220 kV Areakode – Madakkathara feeder was

overloaded and tripped. The Kakkayam and KDPP units connected

through 110/220 kV transformer to Nallalam substation also tripped due to

overload. In this way, as all inputs to Areakode failed, Areakode

substation became dead. (Please note that the indications obtained from

Areakode substation was not clear as the operator became panic as total

northern supply failed).


• The committee discussed the occurrence and recommended that auto

Reclosure feature with carrier inter trip in all 220 kV feeders and

important 110 kV tie lines should be provided to avoid such occurrences..

• It was also informed that there were some limitations mainly due to

protection couplers. If auto Reclosure feature along with carrier inter trip

were put into service for the Malapparamba –Madakkathara this

complete outage could have been avoided.

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• KSEB informed that protection coupler at Areakode has been

commissioned on 15.03.2011 and the Auto Reclosure feature is in

service.

• GM, SRLDC appreciated the steps taken by the KSEB for introduction

of protection coupler with wide band at Areakode.

• KSEB Vide Lr No CESO/LD/GS/PC/2011-12/129 dt 26.04.2011 informed

that Independent Bus bar protection of 400 KV bus at Madakkathara

substation has been completed and the scheme was put in service on

20.04.2011 at 4 PM.

3.5.6) 400/200 KV ICT- 1& 2 tripped at Somanahalli and 220 KV station become dead. The representative from KPTCL explained the occurrence as

follows.

S.NO Date Time Frequency Change 1 12.01.2011 15:28 49.66 Hz to 50.06 Hz

2 17.01.2011 10:36 49.71 Hz to 50.15 Hz

3 25.01.2011 15:45 49.61 Hz to 50.05 Hz

4 31.01.2011 15:35 49.68 Hz to 50.19 Hz

5 31.01.2011 16:24 49.49 Hz to 49.84 Hz

1) 12-01-2011 at 15:28 Hrs. For a transient fault around Hootagalli S/S, line circuit breaker at

TK Halli towards Vajamangala (Hootagalli) tripped on zone-3

indication (Relay with Quadra Mho Characteristic). Simultaneously

ICT-1 & ICT-2 at PGCIL Somanahalli got tripped on MiCOM

definite time over current relay (at 1.7 kA, 252 mSec). Power

supply was normalized at 16.04 Hrs.

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Somanahalli

45MW 52MW

Bastipur

Hootagalli Vajamangala TK Halli Kanakapura Harohalli

2) 17-01-2011 at 10:36 Hrs.

For a fault on Tataguni (NRS) line , the line tripped at Somanahalli

on zone-2 indication (296 mSec, REL-100 relay). Consequently

ICT-1 and ICT-2 at PGCIL Somanahalli tripped. Power supply was

normalized at 10:58 Hrs.

3) 25-01-2011 at 15:45 Hrs. While testing bus bar protection, the same operated accidentally

causing bus shut down. Power supply was normalized at 15:55

Hrs.

4) 31-01-2011 at 15:35 Hrs. For a transient fault in 100 MVA, 220/66 kV transformer at

Tubinakere R/S, ICT-1 & ICT-2 at Bastipur (Mysore - PGCIL)

tripped, consequently ICT-1 & ICT-2 at PGCIL Somanahalli tripped

on over load. Power supply was normalized at 15:55 Hrs.

5) 31-01-2011 at 16:24 Hrs.

While idle charging 220 kV Malur line-2 at Somanahalli bus bar

protection mal- operated due to DC grounding in LBB initiation

circuit. Power supply was normalized at 16:44 Hrs.


• SRLDC informed that 250 msec Setting for zone II is too short.

• SRLDC informed that their settings of PGCIL at other places are at

300-350 msec .

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• Over load setting delay time needs co ordination with Zone 2

timing.

• The Committee recommended PGCIL and KPTCL should

coordinate the settings and avoid feeding the fault current for

longer duration.

• PGCIL was requested to furnish the setting adopted in SR I & II

and feasibility of implementing the settings as requested by KPTCL

• KPTCL vide Lr No CEE/RT& R&D/AEE-1/KCO-81 /17487 dt

18.04.2011 (Annexure IV ) requested PGCIL to keep the settings

above 460 msec to avoid tripping/stopping of BWSSB water

supply.

3.6 Talcher – Kolar HVDC Poles Trippings: NIL 3.7 Minor Trippings

The Minor tripping in the Southern Region are given in

Annexure V as submitted by SRLDC vide Lr No GM/SRLDC/11

dt. 07.02.2011.

4. DELIBERATIONS IN PCC

Regular meeting of PCC held on 07.04.2011 and the

following agenda item were discussed .The list of Participants is

enclosed as Annexure VI . Shri S.D. Taksande, Member Secretary

I/c, SRPC welcomed the participants to the Protection Sub-

Committee meeting . He briefly informed the forum regarding

introduction of working group meetings in PCC. He also highlighted

the decisions taken in the Sub group meeting held on 24.02.2011.

MS (I/c),SRPC also suggested that decisions taken during

the meeting as regards to SPS at Nagjhari, Varahi, UPCL and

protection issues of Kaiga should be put up to the PCC forum. It

was noted that there was no participation from TNEB in the

meeting.

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5 Review of SPS at Kolar:

The proposal for SPS Modifications at HVDC Kolar was

approved in 13th SRPC meeting. In the 10th Protection Sub-

Committee meeting, SRTS-II/PGCIL, informed that all the

equipments except Digital Protection Coupler (DPC) had arrived. A

special meeting was conducted at Kolar on 27.12.2010, PGCIL,

SRTS-II agreed to implement modification at the earliest. PGCIL

may intimate the status of progress.


• SRTS II informed that orders were placed for procurement of Digital

Protection coupler (DPC) and would arrive by the end of June

2011.

• GM,SRLDC informed that the SPS should be implemented at the

earliest, since the power flow in the line was around 2500 MW for

10 Hrs .

6 Requirement of further SPS at Nagjheri:

The issue was deliberated in the 8,9th PCC and SPS has

been approved in June 2009. In the 10th PCC meeting KPTCL had

informed that Nagjheri one unit would be out for one year, so there

was no immediate requirement of SPS during the outage, but PCC

recommended that the SPS at Nagjheri should be put in place by

KPTCL/KPCL.

As per the decision taken in the 10th PCC ,Sub Group meeting of PCC held on 24.02.2011 at Bangalore. The sub group discussed regarding implementation of SPS at Nagjheri and the detailed deliberations as follows.

21

KPCL and KPTCL agreed to implement the SPS Proposed by sub

Group.

KPCL will be the implementing agency for the SPS scheme and

design the logic for the SPS scheme.

SE, KPCL informed that the RTUs were installed by the KPTCL

and the procurement of Hardware for the SPS Scheme was under

progress.

CE, KPTCL informed that the procurement process will take 35 to

40 days.

Member Secretary (I/C) ,SRPC requested KPTCL / KPCL to

implement the SPS within two months and the progress of the

implementation may be informed in the forth coming PCC meeting.

DELIBERATIONS IN THE PCC MEETING

• CE, KPTCL informed the logic for the SPS and also informed that

hardware required for the scheme would be provided by KPTCL

within 45 days.

• The Logic given by KPTCL is attached herewith as Annexure VII

• PCC recommended that the SPS scheme should be implemented

within 90 days.

7 SPS for Kudankulam:

The following had been noted in the 10th PCC meeting .

It was informed that MOU was signed for implementation of SPS at

Kudamkulam.

The unit I was expected by March 2011.

NPCIL had informed SRLDC that the 400 KV switchyard would be

ready by November 2010. It was suggested that PGCIL would

interact with NPCIL to avoid delay.

22

PGCIL SRTS-II had informed that all the equipments except

Protection coupler had arrived and it would take 3 months for

delivery of Protection coupler.


• PGCIL SRTS-II had informed that PLCC link to the SPS is joined

through wide band at Madurai hence the consent of TNEB is needed .

• PGCIL also mentioned that the Maintenance of SPS also needs to be

done by PGCIL and the maintenance personnel /crew entry should be

allowed at the site.

• MS(I/c),SRPC requested PGCIL should write a letter to SRPC

Secretariat then the case would be taken up.

• PGCIL had informed that the SPS shall be ready by September 2011.

• It is also stated that all the substation works has been completed and

the substation was energized.

8 Requirement of SPS at Varahi: Approximately 1050 MW ( more than 450 MW at Varahi and

600 MW of UPCL) had to be evacuated through 220 kV Varahi –

Shimoga D/C line and 220 kV Kemar – Shimoga S/C. 220 kV

Varahi – Shimoga D/C line severely loaded with no N-1 reliability.

In the 7th PCC meeting, SRLDC proposed to have an SPS

scheme at Varahi, which can trip the generation in the event of 220

kV Varahi – Shimoga line outage.

23

In the 10th PCC meeting ,KPTCL had informed that they

would discuss with KPCL and UPCL and come back with a SPS

scheme.

The Sub group of Protection committee discussed regarding

implementation of SPS at Varahi and the details as follows.

Deliberations in the Sub Group Meeting

Regarding SPS at Varahi

If any one of the three lines i.e. Varahi- Shimoga Line 1&2 and

Kemar - Shimoga Line trips Varahi generation has to be brought to

100 MW (at present two units has to be tripped) to avoid over

loading of other lines in the corridor.

When the Fourth unit of Varahi comes into operation (i.e. all the

four units are generating to its full capacity ) and if any one of the

above stated three line trips , three units of Varahi should be

tripped to maintain the generating capacity around 100 MW.

KPCL to identify the tripping sequence of units considering supply

to the auxiliaries are not affected by tripping of units.

KPCL will be the implementing agency for the SPS scheme.

CE, KPTCL informed that the card and other hardware equipments

would be provided by KPTCL and the procurement work is in

progress.

The Scheme will be reviewed when Nandikur- Shantigrama 400

KV (Quad moose Conductor) line commissioned by KPTCL.

GM, SRLDC emphasized the need for the SPS and requested

KPTCL/KPCL to bring the SPS at the earliest.

CE, KPTCL informed that the procurement process will take 35 to

40 days.

24

Member Secretary (I/C) ,SRPC requested KPTCL / KPCL to

implement the SPS within two months and the progress of

implementation may be informed in the forth coming PCC meeting.

Regarding SPS at UPCL

Representatives from UPCL informed the Sub group that another

unit of 600 MW is ready for synchronization.

It was noted that synchronization / commercial operation of the

new unit would be with the consent of the beneficiaries.

UPCL informed the sub group that in case of tripping of Lines the

HP / LP bye Pass will come into operation and reduce the

generation from 600 MW to 300 MW (up to 50 % generation

reduction) with in 5 Seconds.

If only one unit of UPCL is Running, an additional inter trip signal

for tripping of UPCL- Kemar Line to operate the HP/LP bye pass (

in the turbine) should be provided by UPCL to reduce the

generation. So that UPCL can save one line and one unit.

MS(I/c),SRPC requested KPTCL and KPCL to co ordinate with

UPCL for changes in the over current relay settings in the lines to

accommodate enhanced power flow in the other line .

If two units were running at 300 MW each the inter trip signal

should trip one unit of UPCL to reduce the generation from 600

MW to 300 MW.

The Scheme will be reviewed when Nandikur- Shantigrama 400

KV (Quad moose ) line commissioned by KPTCL .

GM, SRLDC emphasized the need for the SPS at Varahi keeping

in view of system security and requested UPCL to implement the

scheme at the earliest.

KPTCL vide Letter No CEE/RT& R&D/AEE-1/KCO-81/17491 dt.

23.02.2011 given their views regarding SPS schemes and other

Protection issues.

25

Member Secretary (I/C) ,SRPC requested UPCL to implement the

SPS within two months time (would come along with Varahi SPS)

and inform the progress of implementation to SPRC with in 30

days.


• CE, KPTCL informed the forum that the over current flow in the

lines is referred to CPRI for guidance.

• Loading of the line app 250 MW (

Single Moose Conductor)

• CE, KPTCL also informed that consent of UPCL is awaited for 5

seconds overloading.

Recommendations:

• PCC requested KPTCL to enhance Over Current set points on

Kemar –UPCL Line should be calibrated to take care of the

contingency for 5-8 Seconds.

• SPS at varahi should be implemented within the agreed time.

9 Requirement of SPS for S1-S2 bid area: SRLDC had suggested an SPS to shed loads of 300 MW at

Salem to limit post contingency stress in S1-S2 corridor whenever

one of 400 kV Hosur-Salem and 400 kV Somanahalli-Salem line

trips. The same was discussed in various SRPC forum meetings

and TNEB had agreed to implement in the meeting held at Chennai

on 12th July 2010. TNEB had identified the loads to be shed in the

SPS scheme and also given a cost estimate of Rs. 25 lakhs.

In the 10th PCC meeting, TNEB expressed that the

expenditure has to be funded from PSDF in line with the decision of

Task force meeting held on 9th August 2010.

26

SRLDC informed that the proposals of funding through

PSDF has been taken up through PSDF Managing Committee.


• Original scheme already has been put up to the task force which

would be taken by the management committee for funding through

PSDF.

• SRLDC informed that they had a meeting with TNEB and TNEB

agreed to get loads at Salem.

• Meanwhile as a interim measure TNEB has identified some loads

at Salem to enhance the loading of Hosur- Salem Line.

• Loads were identified by TNEB and the wiring and associated

works will be taken up by TANTRANSCO..

• The higher loading will be utilized to operate Kadamparai in pump

mode operation.

• SRLDC informed that the app cost of PLC and wiring would be

around ` 50 lakhs apart from ` 25 lakhs for TNEB portion.

10 Requirement of SPS Muddanur:

Muddanur generation (about 800 MW ) has to be

evacuated through four 220 kV lines, 220 kV D/C Chinnakampally

and 220 kV D/C Ananthapur and radial loadings of 200 kV

Pulivendula (120 MW) and 220 kV Yerraguntla (80 MW). In case

of tripping of one of the lines of 220 kV Chinnakampally other line

get over loaded and may lead to cascade tripping.

In the 9th PCC meeting, SRLDC had proposed a SPS

scheme to back down generation in case of one or both 220 kV

Muddanur-Chinnakampally lines trips. The same was also

discussed in the meeting held at Hyderabad with APTRANSCO.

27

In the 10th PCC meeting, APGENCO informed that the

scheme has already been formulated and HQ gave orders for

implementation. It was also informed that the scheme would be

implemented during shut down whenever opportunity arises. The

status of the Scheme may be intimated.


• APGENCO informed that before 15th May 2011 the Pulivendala-

Hindupur line be operational.

• APTRANSO stated that the SPS may not be necessary since the

Pulivendala- Hindupur line is going to be operational in May 2011.

• GM, SRLDC informed the forum that the new line is a part of

system strengthening scheme and not a substitute for SPS scheme

and the SPS should be provided as agreed in the previous meeting.

• APTRANSCO informed that purchase order for the SPS shall be

placed within three months from now.

• The shut down for the lines will be taken during the unit

maintenance period in monsoon and the SPS will be made

operational.

Recommendations:

• The PCC forum Recommended that APGENCO / APTRANSCO to

continue with the SPS proposal and implement the SPS within 3

months.

• SPS would be reviewed keeping in views of commissioning of

Lines/Generating units at Rayal Seema.

11 Requirement of SPS on 400 kV Vijayawada-Nellore line:

SRLDC proposed a SPS to back down generation at

Vemagiri complex in case of tripping of one of the 400 kV

Vijayawada-Nellore line when each line carrying 550 MW . The

28

issue was discussed in various SRPC forum meetings and a

special meeting was held at Hyderabad with APTRANSCO and the

Vemagiri complex IPPs on 31.08.2010. SRLDC had also provided

additional study results as agreed during the meeting.

APTRANSCO may intimate the status. The scheme has already

been placed before in PSDF Management committee for

consideration for funding from PSDF .

On 3rd February ,2011 a meeting was arranged at

Rajamundry regarding Implementation of Special Protection

scheme on 400 KV Vijayawada Nellore DC Lines.

Participants from SRLDC,SRPC, APTRANSCO and IPPs (GMR,

Konaseema, LANCO,GVK & Gouthami ) attended the meeting. The

Implementation of SPS for sudden outages of 400 KV Vijayawada-

Nellore Lines and the problem of High Voltages around Vemagiri

Complex were discussed in detail.


• APTRANSO informed the PCC that they have not yet received

response from the IPP’s.

• MS(I/c) ,SRPC suggested have a separate meeting with IPP’s to

sort out hitches in the SPS scheme.

• It was also proposed have a meeting at Hyderabad the day

before the next OCC (59th OCC) which is scheduled to be held

in Hyderabad.

• MS (i/c) ,SRPC suggested APTRANSO to have a meeting with

IPP’s before the proposed meeting.

• APTRANSCO agreed to pursue the issue with IPP’s and will

revert back to PCC for further guidance and perusal.

12 Review of Islanding Scheme for Ramagundam:

As the out come of the deliberations/discussions in PCC

meetings the islanding scheme of Hyderabad along with the

Ramagundam Thermal Station was commissioned on 16.12.2010.

29

During the Black start procedure discussions with

APTRANSCO, it was felt that the islanding frequency of 47.6 Hz

was too low. It was felt that at these levels the units may pull out of

the grid. It was proposed to raise it to 47.7 Hz instantaneous and

review the same again periodically depending on the setting of the

last UFR level. This frequency would be used for all islanding

events in the southern region other than plant backup islanding

which would be at lower levels .


• It was noted that the UFR settings in the region upgraded from

48.5 Hz to 48.8 Hz,48.2 Hz to 48.5 Hz and 48.00 Hz to 48.2 Hz,

hence the frequency level for initiation of islanding scheme may

also should be modified to a higher level.

• The forum felt that 47.8 Hz should be appropriate for islanding

scheme of Ramagundam (along with Hyderabad island ).

• NTPC agreed to take up the revision issue with the corporate

office and revert back to PCC.

RECOMMENTATIONS:

• It was also decided to go with the same frequency i.e 47.8 Hz

for other Islanding schemes proposed in the southern Region.

• The Jindal and Bellary islanding scheme were also proposed

to separated at 47.8 Hz.

13 Review of Islanding Scheme for Metro’s: During the 4th, 5th, 6th, 7th, 8th and 9th PCC meeting, TNEB

was requested to provide details of the islanding scheme for

Chennai metro and backup Islanding Scheme for Tamil Nadu after

incorporating the latest network changes as well as the load profile

changes.

30

In the 10th PCC meeting, TNEB had intimated that the

islanding scheme for Chennai had been submitted for management

approval. TNEB has submitted the islanding scheme for Chennai

metro vide letter No: CE/P&C/SE/D/P&C/EPC 2/AEE

5/F.SRPC/D.02/11 dated 27.01.2011. TANTRANSCO is requested

to make a Power Point presentation.

13.1) Metro Islanding Scheme – Chennai Back Up Islanding Scheme

The back up Islanding scheme (Metro Islanding scheme) for (1)

ETPS units (2) GMR units and (3) NCTPS units have been finalized

and instructions have been issued for implementing the scheme.

Deliberations in the meeting: • Since the TANTRANSCO representative was not present in the

meeting ,TANTRANSCO is requested to make presentation in the next meeting.

14 Proposal to review the Frequency Settings of UFRs:

During 7th, 8th and 9th PCC meetings, the issue of upward

revision of frequency setting of UFRs i.e., Stage-I to 48.8 Hz from

the present 48.5 Hz, Stage-2 to 48.5 Hz from 48.2 Hz. and the last

Stage to 48.2 Hz from 48 Hz. was discussed. The same was

approved in 14th SRPC meeting. In the OCC meeting, Andhra

Pradesh, TNEB, KPTCL and KSEB confirmed the revised settings.

TNEB yet to confirm the revised quantum. Puducherry may

appraise the PCC of progress of action taken in this regard

Deliberations in the meeting:

• GM,SRLDC requested that UFR tripping operation should be

reported by the constituents.

31

RECOMMENTATIONS:

• PCC recommended that TN & Pondicherry to expedite the revised

UFR setting load relief.

• All the UFRs should be tested /calibrated to avoid any mal

operation.

15 Single Phase Auto-Reclosing on 220 kV and above lines in SR:

In the 7th, 8th & 9th PCC meetings, it was discussed to have

single phase auto-Reclosing scheme on all lines emanating from all

major generating stations including nuclear stations and on all 220

kV and above rated lines.

In the 9th PCC meeting, SRLDC submitted the list of critical

lines for 1st phase implementation. In the 10th PCC KPTCL told that

16 lines from generating stations were being provided with carrier

protection. KSEB told that they have implemented in 33 no. of lines.

Kaiga representative told that atomic units are to be excluded from

auto Reclosure feature. PCC suggested Kaiga to furnish the

reasons for exclusion.

Introduction of Auto-Reclosure facility in Kaiga 400 kV lines and Introduction of Auto Reclosure facility in 230 kV Neyveli – Bahoor

and 230 kV Neyveli – Villianur lines

The outcome of discussion in the Sub Group meeting

regarding provision Single Phase Auto Reclosing facility is as

follows.

Member secretary (I/c),SRPC requested the forum that all the

constituents should provide information regarding status of

Provision of Single phase Auto Reclosure at 220 KV and above

Lines.

32

It was decided to hold the PCC meetings for two consecutive

days, the first day being the working group meeting and would be

discussing the grid incidents and Line/ICT tripping in detail . The

second day being the regular PCC meeting day.

GM, SRLDC expressed concern that no response has been

received from Kaiga regarding provision of Single phase auto

reclosing facility.

GM, SRLDC referred to item No C.12 in the minutes of the 13th

TCC-14th RPC minutes of Northern Regional Power Committee

(NRPC) and stated that Nuclear Power Corporation of India

Limited (NPCIL) decided to implement Single phase auto

Reclosure scheme in the Narora Atomic Power Station (NAPS )-

(Annexure VIII ) MS(I/c),SRPC requested Kaiga to get the details

from NPCIL/NAPS and try to implement the single phase auto

Reclosure in lines emanating from Kaiga keeping in view of NAPS

precedence.

CE, KPTCL submitted the List ( 45 lines) with carrier protection as

a first step. CE, KPTCL informed the group that more lines will be

covered with carrier protection in future.

It was also decided to take up the provision of Single phase Auto

Reclosure scheme in 220 KV and above lines in regular PCC.

It was also decided to create a data base of lines provided with

Single phase Auto Reclosing facility.

Deliberations in the meeting

• Constituents are requested to provide the data regarding the

Lines provided with single Phase auto Reclosing facility and three

phase auto Reclosing facility at the earliest for data base creation.

• The status of implementation auto Reclosure in the remaining lines

also may be intimated.

33

• Kaiga informed that the minutes of the sub group meeting is

forwarded to corporate office. It was informed that as on date the

single phase auto reclose scheme is not been implemented at

Narora. However the reply will be communicated to the PCC forum.

• GM,SRLDC expressed concern that the issue was continuing for

the last 2-3 years without any positive response from NPCIL.

• PCC forum requested Kaiga to furnish the action taken to provide

Single phase auto Reclosure.

• SRTS II/PGCIL suggested Puduchery should go for Numerical

relays in place of static relays.

• NLC informed that Neyveli Bahour Line is provided with Numerical

type relays. The relays were tested and breaker balance works will

be completed shortly. Single phase auto reclose will come in to

operational by September 2011.

• SRTS I/PGCIL pointed that the 4 lines emanating from Nunna

(Vijayawada)- Vemagiri (D/C), Vijayawada-BTPS were in Non auto

mode.

• APTRANSCO informed the forum that they will make auto

Reclosure feature will be made available in the stated 4 lines.

RECOMMENTATIONS:

• The Protection set points of 220 KV and above network of all the

utilities should be furnished to SRPC and SRLDC for data base

creation.

• The Bus Bar Protection scheme operational or otherwise in the

Substations should be reported.

34

16 Emergency Load Disconnection Scheme during sustained

over drawal at Low Frequency.

During 7th, 8th and 9th PCC meetings, SRLDC proposed a

scheme to trip the loads corresponding to those of the Constituent

who is overdrawing alone. The same was discussed in various

SRPC forum meetings. AP & Kerala have implemented the scheme. Tamilnadu has

to provide additional Load of 79 MW. Karnataka and Pudhucherry

had initiated action in this regard.


• CE, KPTCL informed that the scheme is ready for Karnataka and

the Management approval is awaited for implementing the scheme.

.

RECOMMENTATIONS:

• PCC forum recommended that the as per the IEGC guidelines the

Emergency Load Disconnection Scheme is mandatory hence the

scheme should be put in to use at the earliest by all the

constituents.

17 Islanding scheme for Bommur. Due to the large number of gas generators in north coastal

AP, the Black start restoration plan becomes complicated and time

consuming. It was felt that an islanding scheme for a few gas units

at 220 kV level along with loads at Kakinada, Bhimadolu and

Bommur would be looked.


• APTRANSO informed the forum that 40-50 % of the Loads were in

UFRs and other protection schemes,

• It was also informed that the island may not survive (i.e 500-600

MW).

35

• It was noted that during 2001 disturbance the island had survived

but the IPP’s had objected to it.

RECOMMENTATIONS:

• PCC recommended that there were no stable generation and very

less base load was there and the survival of the island is difficult

therefore the scheme may be deliberated with bigger generators

and sufficient loads.

• SRLDC informed that 800-1000 MW load was covered under

UFRs.

• PCC recommended APTRANSCO to study the bigger island and

revert back to PCC.

18 Providing synchronizing facility at Key Stations for black start restoration:

This issue was highlighted in the 44th to 55th OCC, SRPC

meetings and PCC meetings. The current status of synchronizing

equipment installation at key stations is as follows:

S.No Sync. facility requirement at station Status

1 Peenya station both at 220/110/66 To be provided during R&M works

2 Hubli To be provided during R&M works

3 Lingapura Yet to confirm the date

4 Shimoga Already in place

5 Ambewadi, BBwadi, ML Pura, Lingsugur, Guttur 220 kV

Yet to confirm the date

6 Kayathar 110 kV Action being taken

7 Shornur Within two months (Sept.2010)

8 Kaniyampet Provided

9 Dindi & Kalwakuruthy Facility made available(June’10)

10 Talapalli Facility made available(June’10)

11 Shapoornager Facility made available(June’10)

12 Chandrayanagutta & city ring main stations

Yet to be provided

The constituents are requested to expedite the same. A

communication was received from TN stating that the synchronizing

equipment at Kayathar 110 kV was not required. The same was

36

discussed during the meeting with TANTRANSCO and other constituents

including SRPC & SRLDC during the Black start restoration meeting held

on 27.01.2011. Considering the fact, that restoration is a parallel

procedure and also that critical assets like TTPS, MPCL, gas IPP/CPP

and eventually KOODAMKULAM stations get startup supply from Hydro

stations at Periyar, Kodayar and Papanasam-Servalar, it is felt that the

synchronizing equipment at Kayathar 110 kV is very much necessary. As

per the earlier proposal of SRLDC, phase-2 of the proposal involves

having synchronizing equipment at all 220 kV and above stations.

Members may discuss and deliberate.


• The revised list of Stations with Synchronization facility should be

given by SRLDC.

• As per the minutes of the meeting of Black start procedure for

Tamilnadu (Annexure IX ), the Synchronization facility should be

provided at Kayathar. SRLDC is requested to take up the issue with

TNEB with a copy to SRPC.

• SRLDC enquired about the synchronizing facility at Shornur and

KSEB informed that the orders has been placed to Easun Reyrolle

but no response was received from the company.

• KSEB also informed that very limited synchronization was taking at

this point and all the adjoining stations were provided with

synchronization facility.

• SRLDC informed that as per the Black start procedure 2011 , two

stations black start synchronization was planned through Shornur,

hence the synchronization facility at Shornur is vital one.

RECOMMENTATIONS:

• Every Generator should have synchronization facility.

• Synchronization facility should be provided at Kayathar and

Shornur.

37

19 Protection aspects of Wind Turbines:

During the 9th and 10th PCC meeting, SRLDC had

emphasized the need to examine and optimize the protection

practices adopted for Wind Turbines as penetration levels are

increasing. In the meeting, Tamil Nadu & Karnataka are requested

to put up proposals for the same and make a power point

presentation.


• It was noted that the protection aspects of Wind turbines are unique

in nature.

• PCC suggested that protection aspects may be given by the Wind

Turbine Manufacturer.

• AGM,SRLDC informed that the presentation by Wind Turbine

Manufactures M/s Suzlon may be arranged in Afternoon session of

the working group meeting of 12th PCC.

20. Tripping of 400 / 220 kV ICTs of POWERGRID on Directional

Over current Relay.

There were many instances of opening out of LV side of

ICTs owned by PGCIL due to fault on 220 kV/110 kV/66 kV

network, notably at Somanahalli (5 time in January 2011) and at

Narendra. Unwanted tripping of important ICTs especially at Metro

stations could lead to power interruptions . During the last PCC

meeting, this issue was discussed and it was felt that the setting of

directional OC relays needs to be enhanced to 500 m.sec to allow

relays on 220/110/66 kV side to pickup. Additionally, constituents

may ensure the healthiness of relays and Bus Bar protection

schemes at these stations to clear the fault instantaneously rather

than delayed tripping.

38

20.1) Regarding Downstream tripping of PGCIL ICTs

In reply to power Grid’s Letter dated 18.12.10 CE (P&C) of

TNEB stated that the Protection philosophy of the lines has been

discussed in the forum and is being adopted by all the constituents.

In the letter under reference the PGCIL has stated that the ICTs are

tripping due to downstream faults. It is also to be noted that the

ICT trippings are before the Zone 2 time of 0.4 Sec. It is requested

that the coordination between the ICT and feeder protections may

be taken up in the forum.


• Since there was no representation from TNEB , the agenda item

was not taken for discussion.

20.2 ) (i) Frequent feeding of fault current by POWERGRID ICTs due to delayed clearance of faults in downstream system. Select Case studies on Trip Analysis (More elaborately furnished in attached Annex I and the same point is being taken up for discussions in the 15th TCC meeting. (PGCIL agenda).


• KPTCL has expressed serious concern over the low set points adopted by PGCIL.

• KPTCL expressed that as per CBIP guidelines only IDMT features should be adopted.

• SRTS I/PCGIL expressed that PGCIL has lost Gazuwaka transformer and few transformers in the Northern region due to feeding of fault current from downstream utilities.

• As a common protection philosophy to safeguard PGCIL’s equipments low set points were adopted by PGCIL.

• SRLDC also concerned about the low set points adopted by PGCIL and requested PGCIL to adopt IDMT characteristics.

• APTRANSCO informed that the their 315 MVA Transformers were set with IDMT characteristics and operating safely.

• KPTCL informed that the fault current level was 2 KA . • SRLDC pointed that the transformers were type tested for 40 KA. • SRTS II requested that the downstream faults in the Karnataka

system should be cleared instantaneously. • PGCIL requested to furnish the set points adopted in other regions

39

RECOMMENTATIONS:

• All the constituents are requested to furnish the set points provided in their system to SRPC and SRLDC at the earliest.

20.2.)(ii) Review of Zone-2 and Zone-3 time delays in 220 kV Transmission lines and coordination with up-stream ICT protection schemes.


The agenda item was Discussed under 3.5.6

21 Islanding scheme for RGCCPP, Kerala. During the Black start restoration review meeting held at

SRLDC on 21.01.2011, it was felt that RGCCPP could go for an

island with Pallom loads of about 100 MW as opposed to a house

load of 10 MW at a pre decided frequency.


• The issue was discussed and findings are given below. • KSEB was requested to study transient behavior of RGCCP

machines. • PCC forum opined that the small Island may not survive and

formation of bigger island may be considered with adjoining generators and loads.

• KSEB informed that it had furnished requested data in proper format to NTPC for modeling.

• KSEB requested SRLDC to provide Theni- Thirunelveli Line data. • SRLDC informed KSEB that they can provide the standard Line

data. 22 Islanding scheme for Jindal, BTPS. M/s. Jindal has an islanding scheme in operation where 1 x

100 MW and 1 x 133 MW units island with 180 MW load of its steel

plant.As JSW has a load of 500 MW, M/s. Jindal was asked to

explore possibility of a second island.

40

M/s. KPCL was also requested to formulate an island for BTPS with

radial loads at Munirabad, Kustigi and Sindhanur.

KPTCL would need to provide synchronizing facility at 220 kV

Lingapura to synchronize these islands. These islands would be

very much essential to give startup to RTPS .


• It was noted that during the partial black out on 18.03.2011 the two

units of Jindal were survived.

• The PCC forum requested KPTCL to provide send the details of

Jindal islanding scheme with set points, logic etc.

• SRLDC suggested for a bigger islanding scheme.

23. Agenda from Kaiga .

Kaiga/NPCIL vide Lr No NPCIL/KGS-1&2/MS/SRPC/S/2011

dt. 07.02.2011given the following points for discussion and

deliberation in the meeting.

23.1) As per MOM of 10th PCC, bus bar protection to be provided at

Narendra and Ambewadi sub-stations

23.2) During the period from September 2010 to January 2011 there

were five outages in 400 kV system due to faults. Three outages in

Kaiga-Guttur line-2, and two outages in Kaiga-Guttur line-1

respectively.

23.3) There were two outages in both 220 kV lines i.e., Kaiga-Kadra line

and Kaiga-Kodasalli line because of faults in Kadra-Karwar line.

23.4) Tripping of 400 kV lines is a major concern as all four units at

Kaiga site are operating. The reference given by Kaiga is attached

here as Annexure X.

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• Ambewadi S/S: CE,KPTCL informed that Installation of bus bar

protection at Ambewadi S/S 220 kV bus taken up along with R&M

works. It is informed that DPR (Detailed Project Report) has been

approved by the management, tenders will be called shortly for

execution of these works including bus bar protection.

• Narendra S/S: KPTCL informed that DWA has been issued to M/s

Easun Reyrolle Ltd on 13-10-2010 for providing bus bar protection

and the work has been initiated.

• PCC forum requested KPTCL to furnish the detailed report of the

stated disturbances at the earliest.

24 Agenda from Power Grid Power grid Vide Lr No SR-II/OS/F-42.2/2010-11/450 dt. 07.03.2011 sent their agenda points

24.1) Remote tripping of 400 kV Kudamkulam – Thirunelveli 1, 2, 3 and 4 lines during Operator hand tripping of said lines from Kudamkulam APP end.


• PGCIL informed that emergency hand trip is not envisaged for the line.

• It was noted that at Kudankulam LBB, Remote end tripping, Bus Bar protection etc has to be provided.

• PCC forum requested SRTS II to take up the case with NPCIL with a copy to SRPC& SRLDC.

Follow up Points given by Power grid

24.2) Busbar Protection at KSEB 400 kV Trichur S/S: KSEB have installed Busbar Protection Relay (PBDCB) in the panel and wired, as per information available to our site. However commissioning is being delayed. KSEB have to give their schedule for commissioning so that the KSEB CT wires can be removed from Busbar Protection.

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• It was decided to take up works on 19&20 /04/2011 at Trichur S/S

without Shut down.

25).Proposal for Power System Protection Audit.

In the Sub Group meeting of Protection Committee it was proposed to go for Protection Audit of 220kV & above Voltage system in the Southern Region. The following deliberations were made.

Member Secretary (I/c), SRPC informed the forum that the

constituent States should keep their protection system healthy.

It is proposed to have uniform Protection philosophy in the

Southern Region to have a safe and reliable grid and to avoid

indiscriminate tripping.

As per the Grid connectivity standard notified by CEA it is the

responsibility of the utility to keep its protection system healthy.

The constituents are requested to come up with a proposal for

power system protection audit in the forth coming PCC

The protection audit would cover following scope:

To carry out relay coordination studies for the different protection schemes.

Review past record (say for 2 years) of Normal & Abnormal

Tripping.

To assess the conditions of existing relays.

Review of testing history of Protection relays and EHV Yard equipments.

Recommend modern Protection relays with improved

features.

Up gradation of protection system.

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Deliberations in the meeting • Member Secretary (I/c),SRPC requested constituents to come up

with views / Proposals on protection audit so that approval of SRPC could be taken and Funding etc could be finalized.

• The Protection Audit would review the implemented protection

schemes / philosophy & settings in the 400kV & 220kV feeders of

corresponding state grid which includes protection of Generator,

Transmission line, Transformer, Reactor, Circuit Breaker, Bus Bar

and Series Compensation Device.

• SRLDC desired Self Declaration of Healthiness of all the protection

scheme of the constituents. In this regard APGENCO questioned

about necessity of self certification by the generators.

• AGM,SRLDC pointed that the so many system occurrences were

not brought to the notice of the Real Time system

Operator(SRLDC).Since SRLDC was seeing the southern region

system as whole , the information provided by the constituents will

help them in managing the system in a better way. PCC forum

informed that control room information should be given to the

system operator.

• It was also noted that Gooty Nelamangala Line back up protection

was out for 6 months. The same was not informed to

SRLDC.PGCIL informed that they will send the information.

• In this connection following data/information is proposed to be

collected from constituents.

• is requested that all the constituents to furnish the following with in

fifteen days (as given in the format) from the date of issuing the

minutes.

• (i) Self Certification by utilities ( Annexure XI)

• (ii) The details of relays provided in their system and protection

settings adopted by them (Annexure-XII).

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• (iii) Status of Bus bar protection for Southern Regional

Constituents. (Annexure XIII).

26. Provision of various B/B Protection at 220 kV Substation by KPTCL

Provision of Bus bar Protection scheme at 220 kV KPTCL Narendra S/S – arrangement of LBB trip matrix for 220 kV Bus Section CBs.

The following deliberations were in the Sub Group meeting of PCC. CE, KPTCL submitted the list of 45 Lines provided with carrier

protection’s, KPTCL also informed the status of provision of Bus

bar protection at following KPTCL stations.

Hubli S/S : Tenders are being invited for replacement of 3 core

CTs by 5 core CTs including providing bus bar protection.

Manager (OS), Power grid SRTS II requested that in case of such

delays in commissioning of Bus bar protection at KPTCL stations,

the faults in 100 % of transmission lines of KPTCL should be

cleared instantaneously, with zone -2 time delay of 200 ms and

Zone 3 time delay of 300 ms, so that such remote faults could be

taken care and cleared on time.


• Lingapura S/S: CE,KPTCL informed that DPR (Detailed Project Report)

has been prepared for providing bus bar protection scheme along with replacement of C & R panel, isolators & other works. The work will be taken up shortly.

27 Agenda from KSEB (for information to PCC)

Chief Engineer (Trans), KSEB Vide Lr No CESD/LD/GS/Protection committee/2010-11 /1721 Dt. 09.02.2011 sent the Grid Disturbance Report of Kerala system from 16.09.2010 to 31.01.2011.

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Present status on the following issues, which figured in the

10th Meeting of Protection Sub-Committee meeting may please be discussed.

28. Pilot PMU Project: The 9th PCC recommended for pilot project for Phasor

Measurement Unit (PMU). The Constituents are also agreed for the

pilot project for PMU. SRLDC proposed for 6 numbers of Phasor

Measurement Units for the Southern Grid at an estimated

expenditure of Rs.4.0 Crores. The pilot PMU project was approved

by the 14th SRPC meeting held at Kochi on 27th August 2010. It

was also noted that the entire funding of the project would be

carried out through PSDF and the same has been put up to CERC

Task Force for funding from PSDF.

SRLDC was asked by the SRPC forum to involve the

constituents right from the beginning of the implementation of the

project .


• SRLDC informed that the proposal would be taken up

appropriately.

29. Islanding scheme for NTPC, Talcher STPS:

In the 7th Protection Sub-Committee meeting NTPC said that a special type of testing was involved, since the inter connector breaker needed to be opened. They said that NTPC Corporate Centre was contacting a German Body in this regard. Special equipment needed to be installed in the turbine during the testing. In the 8th Protection Sub-Committee meeting DGM, NTPC said that the islanding scheme at Talcher Stage-II was very complex due to the peculiar nature of the evacuation with HVDC poles. They have also said very few experts were available all over the world to assist in formalizing the scheme. Despite several efforts by NTPC, the consultant was yet to be finalized. MS, SRPC said that there was no evident progress in the finalization of the scheme. He suggested that the issue could be referred to CEA if NTPC desires so. Expert opinion of CPRI or other consultants could also be sought.

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In the 9th PCC meeting, AGM, NTPC informed that the proposal by the German Company was under examination by their Engineering Division. The status of the scheme may be informed to the forum.


• NTPC said that the proposal was too complex and no consultant is willing to take up the work .NTPC requested the forum to drop the item from agenda.

• PCC forum agreed to drop the proposed islanding scheme of Talcher.

30. SPS Scheme for Cascade Tripping in Peenya

In the 8th Protection Sub-Committee meeting it was decided

to implement a SPS scheme for cascade tripping in Peenya. The

status of the scheme may be intimated to the Committee.


• CE,KPTCL informed that a scheme has already been provided to shed

about 100 MW by tripping 66 kV feeders at Peenya if any one among the

three lines between Peenya-Nelamangala trips.

• The details of 66 kV feeders are as follows.

a) TG Hally line : 35 – 38 MW

b) NRS-1 line : 45 MW

c) Widea line : 25 – 30 MW

d) Total : 95 – 113 MW

• KPTCL also informed that two days prior to the meeting (i.e on

05.04.2011 ) the SPS scheme was put in to service.

• PCC forum suggested KPTCL to provide the complete scheme

details to SRPC & SRLDC with Logic ,Single Line Diagram and

settings etc at the earliest. So that same could be finalized in the

PCC forum.

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31 . Voltage Control Relays as per IEGC .

As per 5.2.(t) of System Security Aspect of Operating Code (Part -

5) of IEGC, voltage control relays should be provided. The IEGC “ The

Users, CTU and STUs shall provide adequate voltage control measures

through voltage relays as finalized by RPC,to prevent voltage collapse

,and shall ensure its effective application to prevent voltage

collapse/cascade tripping. Voltage Relays should be provided as per

IEGC Guidelines” . The following deliberations were made in the 10th

PCC meeting.

MS(I/c),SRPC said that voltage relays could be provided at

specific stations after carrying out all compensation and after

sensitivity study etc.

When all shunt compensation are in place study can be done

and nodes can be identified. It was informed that SRLDC have

identified Sriperumbudur, Kalinathapattu, Chittoor, Almatti after

studies.


• SRLDC informed that they have identified the nodes where Low

Voltages conditions prevailed. They nodes Somanahalli, Cheyyur,

Sriperumbudur, Kalinathapattu, Chittoor, Almatti.

• PCC recommended for provision of Voltage control relays in the

following nodes i.e. at Somanahalli, Cheyyur, Sriperumbudur,

Kalinathapattu, Chittoor, Almatti

However the suggestions and views of constituents is invited for

provision of Voltage control relays at these nodes.

32. Date & venue of the next meeting.

The next PCC meeting will be held in July 2011.the exact date and

venue shall be communicated in due course.

SOUTHERN REGIONAL POWER COMMITTEE BANGALORE … · 7th April in the Conference Hall of Southern...

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