Ph. : 26513265 e-mail : nrebops@yahoo.com Fax: 26865206 Website: www.nrpc.gov.in

भारत सरकार Government of India

उ तर के्षत्रीय िव युत सिमित

Northern Regional Power Committee

18-ए, शहीद जीत िसहं मागर्, कटवािरया सराय नई िद ली - 110016

18-A, Shaheed Jeet Singh Marg, Katwaria Sarai, New Delhi-110016 No. NRPC/SE (O)/17-PSC/11/ Dated: 16.04.2012

FAX MESSAGE From : Superintending Engineer (O), NRPC. To : Members of Protection Sub-Committee 1. Director (P&C)/BBMB, Chandigarh, Fax-0172-2652054 2. General Manager (O&M) DTL, New Delhi, Fax-23221059 3. GM (O&M), Delhi Transco Limited, New Delhi, Fax-23366160 4. GM (T), Common Services IPGCL, New Delhi, Fax-23370247 5. Chief Engineer (TS), HVPNL, Panchkula, Fax-0172-2591244 6. SE (M&P), HVPNL, Dhulkote , Haryana, Fax-0172-2540014 7. SE (PPM), Haryana Power Generation Co. Ltd., Panchkula , Fax-0172-2586836 8. Chief Engineer (Transmission), HPSEB, Hamirpur, Fax-01972-223435 9. Chief Engineer (Comml. & Survey Wing) PDD, Jammu, Fax-0191-2474233 10. Chief Engineer (P&M), PSTCL, Ludhiana, Fax-0161-2741280, 2451491 11. CE(M&P), RRVPNL, Jaipur, Fax-0141-2291891 12. SE (Electrical), RRVUNL,Suratgarh, (Rajasthan), Fax-01509-245299 13. Superintending Engineer (T&C), UPPCL, Meerut (U.P.), Fax-0121-2666062 14. Chief Engineer, (L-2), UPRVUNL Lucknow, Fax-0522-2287822, 2287880 15. DGM (T&C), PTCUL, Dehradun, Fax-0135-2760331 16. Chief Engineer (O&M), NHPC, Faridabad, Fax-0129-2272413 17. Chief Engineer (O&M), NPCIL, Mumbai, Fax-022-25563350 18. GM (O&M) NR – I, PGCIL, New Delhi, Fax-011-26601079 19. GM (O&M), NR-II, PGCIL, Jammu, Fax-01951-237186 20. Chief Manager (TS), N.R.L.D.C, New Delhi, Fax- 011-26852747 21. GM (OS) NTPC Ltd., Noida, Fax-0120-2410082, 2410068 22. DGM (Maintenance), SJVNL, New Shimla, Fax- 0177-2673283 23. DGM (O&M), THDC India Ltd., Tehri Garhwal, Fax No 01376-236305 24. Director (GM division), CEA,New Delhi, Fax-011-26109750 …............................................................................................................................................ Sub:-Agenda for the 17th Protection sub Committee Meeting on 24.04.2012

The 17th Protection sub Committee Meeting will be held at 10:30 Hrs on 24th April, 2012 at

NRPC, New Delhi. The Agenda can be down loaded from NRPC website at

http://www.nrpc.gov.in.

Kindly make it convenient to attend the meeting.

-Sd/- Ajay Talegaonkar

Superintending Engineer (O)

NORTHERN REGIONAL POWER COMMITTEE AGENDA

FOR 17th MEETING OF PROTECTION SUB-COMMITTEE

Time of meeting : 10.30 Hrs. Date of meeting : 24th April, 2012 Venue : NRPC, New Delhi

A . C O N F I R M A T I O N O F M I N U T E S

A.1 CONFIRMATION OF MINUTES OF 15th MEETING OF PROTECTION SUB-COMMITTEE. Minutes of 16th meeting of Protection Sub-committee, held on 22nd December, 2012 were issued vide letter no. NRPC/SE (O)/16-PSC/11/ dated 13.03.2012.The Minutes are available on NRPC’s website at http://www.nrpc.gov.in . As no comments have been received from any of the constituents, the sub-Committee may confirm the same.

B. ITEMS FOR FOLLOW UP ACTIONS

B.1.DATA FOR CO-ORDINATION OF RELAY SETTINGS FOR PROTECTION OF TRANSMISSION LINES, SINGLE PHASE AUTO RECLOSURE SCHEME OF DIFFERENT UTILITIES / ORGANISATIONS B1.1 Details of Relays Settings for Transmission Lines B.1.1.1 Information as per Annexure-I from UPPTCL, UPRVUNL, PDD J&K, PTCUL, HPGCL and PSPCL is still awaited. Utilities are requested to submit the details through e-mail (nrpcprotection@gmail.com). The information received from all other utilities has been sent to members of Protection Sub-committee via e-mail dated 10th April, 2012. B1.2 Single Phase Auto Re-closure at 400 and 220 kV Transmission Lines B.1.2.1 In 15th PSC meeting held on 18.08.2011, BBMB had intimated that carrier-inter-trip feature (Carrier aided protection of transmission line) of following lines is not enabled due to faulty PLCC channels ( of PSTCL and HVPNL ends)

Sr.No Transmission Line (220

KV)

This end Other end

Status of carrier protection

1 Jamalpur-Dhandari-I&II

BBMB PSTCL Not Available

2 Jalandhar-Butari

BBMB PSTCL -do-

3 Jalandhar-Jamsher-I&II

BBMB PSTCL -do-

4 Barnala–Lehra-Mohabbat

BBMB PSPCL -do-

5 Samaypur-Badshahpur

BBMB HVPNL Not Available

6 Samaypur-Palwal-I&II

BBMB HVPNL -do-

7 Samaypur-Palli-I&II

BBMB HVPNL -do-

8 Bhiwani-Bapora-I&II BBMB HVPNL -do-

Further in 16th PSC meeting held on 22.12.2012, representative of PSTCL stated that for lines from Sr. No 1 to 3, complete works would be completed within one month. BBMB was requested to take up matter of 220 kV Barnala–Lehra-Mohabbat line with PSPCL. Representative of HVPNL informed that issue regarding lines belonging to HVPNL would be resolved within six months. PSTCL, BBMB and HVPNL may update the status B.1.2.2 In 16th Protection Sub-committee meeting, DTL had indicated that tele-protection scheme would be completed within one year. DTL may update the status. B.1.2.3 In the 24th NRPC meeting held at Mahabaleshwar, NPCIL had informed that they would progressively commission Single Phase Auto Reclosure Scheme on lines emanating from RAPP-B. NPCIL may update the status of implementing the same. B.2 commissioning of carrier scheme on Transmission Lines B.2.1 In 15th PSC meeting held on 18.08.2011, PSTCL had stated that during commissioning of carrier schemes on transmission lines in Punjab connected with POWEREGRID, it had been observed that in some cases the Direct Trip signal was through TNC handle while in some cases it was through distance relay with command being issued on operation of Distance Protection Relay (DPR) in zone-II or zone III or on directional earth fault or Switch On To Fault (SOTF). He had requested for a clear directive on this issue. In the same meeting POWERGRID had stated that they would consider the issue raidsed by PSTCL and would respond in the next PSC meeting. As no consensus could be reached in 16th PSC meeting held on 22.12.2012, a sub-group was constituted with following members:

1. Sh. Kuleshwar Sahu, CM, POWERGRID 2. Sh. Rajbir Singh, EE, PSTCL 3. Sh. Kavinder Singh, SE, UPPTCL 4. Sh. M. K. Singhal, SE, RVPNL 5. Sh. T. Muthu Kumar, Sr. Engg. , NRLDC

A meeting of the group would be held on 24.04.2012 at 15:00 hrs at NRPC, New Delhi.

C . N E W I T E M S F O R D I S C U S S I O N

C.1 Generic recommendations of protection audit of Delhi System conducted by CPRI C.1.1 It was decided in 22nd TCC and 25th NRPC meeting that report of Protection Audit carried out by CPRI for Delhi System be made available to all STUs and would be discussed in Protection Sub-Committee. Further it was agreed that wherever feasible, recommendations of CPRI which are of generic nature should be implemented by the STUs. Accordingly soft copy of the report has been sent to all STUs. Following are the generic recommendations: Recommendation No. 13.1- Review of protection schemes / philosophy 13.1.1 Protection of 400 kV Transmission lines (i) Any one of the Main 1 or Main2 relays shall be replaced with any one of the following: - Distance relay of different type

- Directional Comparison type - Phase segregated differential protection - Phase Comparison type In earlier days phase comparison type of protections were used, but now these have become obsolete and later Distance relays from different manufacturer with different principle of operation was used but now a days differential protection is being used. Differential protection is preferred because of the reasons that it is stable during power swing conditions , differential protection with Fibre optic links are reliable. (ii) A separate E/F Protection shall be provided for all the lines.

13.1.2 Protections for 220 kV Transmission Lines (i) Carrier aided distance protection schemes shall be used for distance protection of 220kV lines which helps in faster clearance of faults over the entire line length.(Ref: CBIP guidelines) (ii) In places where main1 and main 2 are distance relays, one of the protections shall be replaced with differential protection and an additional relay shall be provided for E/F(51N). In case of Numerical Distance relay, the built in E/F function can be used. iii) Single phase Auto reclosure feature shall be enabled to avoid mal operations during transient faults. 13.1.3 Protection of Transformers It is recommended that overload protection relays shall be provided for all transformers and it shall be set for alarm and not for tripping (ref: CBIP guidelines). Recommendation No 13.2.1.1- Distance protection setting The following uniform procedure/ philosophy is recommended based on the NRPC guide lines. Zone1: set to 80 % of protected line impedance with no intentional time delay. Zone2: set to protected line impedance plus 50 % adjacent shortest line impedance or 120 % of protected line impedance whichever is higher, the time delay of 0.3 seconds. Zone3:120 % of protected line impedance plus Adjacent Long line impedance. Or 100 % of protected line impedance plus Adjacent Long line impedance plus second adjacent Long line impedance whichever is lower also it shall not reach the next lower voltage level. Resistive reach: shall be set such that it is less than maximum expected load.

Recommendation No 13.2.1.4- Directional over current/Earth fault protection setting Following procedure is recommended to be adopted: The pickup setting of directional over current relay for all lines is set to 100 % of CT secondary rating , The pickup setting of directional earth fault relay is set to 20 % of CT secondary rating and the time multiplier setting is selected such that the over current relay/earth fault relay of protected line will operate before the backup distance relay of adjacent line operates for the fault at the remote end of the line. Phase fault current is to be considered for back up over current relay and single phase to ground fault current is considered for backup earth fault relays. Recommendation No 13.3- Healthiness of PLCC a) The faults in the carriers, protection couplers and wiring have to be addressed immediately with the help of respective suppliers to restore carrier protection. For this a core team for maintenance of Power Line carriers, protection couplers, PLC exchanges and related work may be set up. This team shall be provided with testing equipment comprising of Selective Level meter, Signal generator, Frequency counter, Multimeter and tools for wiring. b) As the ABB make ETI carriers and NSD 61 protection couplers have served for more than 9 years and as the spare support will not be available from the OEM, and further as these equipment

are in critical and important 400 kV links, it is suggested that 60 % of these shall be shifted and relocated for important 220 kV links, and 40% can be retained as spares. The 400 kV links shall be provided with new ABB make ETL carriers and NSD 50 protection couplers, which are found to be very reliable and stable. c) It is recommended that a 4 member team in Protection and communication shall be trained on testing and maintenance of Power line carriers and protection couplers. This team shall further train Engineers at respective stations for routine testing and fault detection. Recommendation No. 13.7- Disturbance Recorder and Event Logger healthiness and suitability Where ever static relays are present, the details of which are presented in section 6.3, they are to be replaced by Numerical relays with suitable IRIG-b and SNTP cards. Existing numerical relays are to be upgraded with IRIG-B and SNTP cards as all of the existing numerical relays do not have the time stamping features.

Recommendation No. 13.8- Time synchronizing unit: SNTP & IRIG-B protocol facility shall be enabled in the TSU in all 220 & 400 kV substations. Recommendation No. 13.9- Field test procedure for Relays It is recommended that periodic maintenance testing shall be carried out once in a year for Electro mechanical relays and once in 2 years for numerical relay. Trending of performance data shall be carried out which will provide an understanding of relay performance deviation over time required for judging the status and predicting possible mal functioning. The detailed test procedures formats (format 1- format 18) for different relays used in DTL system in the section 9.1of Report is recommended as the existing procedures were found to be not exhaustive. By using the Relay test kits, Maintenance/Periodic testing time can be reduced drastically in comparison with the conventional methods and also provides measurement results with high accuracy, for Numerical Relays in particular. Test Reports can be automatically generated in the formats required. Relay Test kits of various Makes, Models and features are available in the market. However based on CPRI experience the following kits are recommended.

1. OMICRON make Relay test Kit. Model : CMC 256 plus 2. Doble make Power System Simulator Model : F6150

Members may Deliberate

C.2 The following tripping were discussed in 16th PSC. The D.R/ E.L print and analysis reports are still awaited from respective constituents

Date Time Detais of tripping Station/ Utility Remarks

29-May-11 8:52

Multiple tripping at 400/220kV Muradnagar & Moradabad (UPPTCL) UPPTCL

Report awaited.

1-Sep-11 04:45 hrs Multiple tripping at 220kV Mainpuri, (U.P) Sub-station UPPTCL

Report awaited.

13-Sep-11 11:34 hrs

Tripping of lines in 220kV U.P grid & tripping of ICT’s at 400/220kV Mainpuri Substation UPPTCL

Un-cleared fault in 220kV line system lead to tripping of Mainpuri(PG) ICT#1 & 2 on baprotection. Report from UPPTCawaited.

20-Sep-11 22:12 hrs Loss of generation of 240 MW at Parichha TPS UPPTCL

Report awaited.

31-Aug-11

12:09 hrs & 12:20 hrs

Multiple tripping, generation loss & load loss in western U.P UPPTCL

Report awaited.

14-Nov-11 04:39 hrs Multiple tripping at 400kV Mau (UPPTCL) Substation UPPTCL

Report awaited.

C.3 Tripping referred by OCC The following trippings were discussed in OCC meetings. Further discussion is required at PSC level C.3.1 Loss of generation at Anpara TPS & Anpara-C TPS on 7th December 2011 at 20:25 Hrs Running units 1&2 at Anpara TPS, Unit-1 at Anpara-C TPS had tripped during the incident. Generation loss of 900MW had occurred. 400kV Anpara-Sarnath ckt-1, 400kV Anpara-Mau line, 400kV Azamgarh-Mau line had tripped during the incident. 400kV Anpara-Sarnath ckt-2 was out of service. In 71st and 72nd OCC meetings, UP SLDC was asked to analyze the incident, and submit a detailed report. UPPTCL had submitted their report dated 26.03.2012. As per report transient fault had occurred in 400kV Anpara-Mau line. The fault was close to Mau end. Zone-1 had operated at Mau end and Zone-2 picked up at Anpara end. Instantaneous tripping through Carrier aided tripping could not be achieved at Anpara end due to unhealthy PLCC link and Anpara end tripped in Zone-2. Generator neutral over-current had picked up for all the three 210 MW units which led to their tripping. UPPTCL has reffered the matter regarding the setting for Generator Neutral Over current relay to the Protection Sub-Committee. UPPTCL may appraise PSC about the healthiness of PLCC link & testing of distance protection relays of 400kV Anpara-Mau line. Further Chief Engineer, Anpara Thermal Power Station in his letter dated March 15th, 2012 to SE(O), NRPC has requested for consent to replace the present IDMT electromeachincal relay to a definite type digital or solid state O/C relay with time delay of 1.0 sec. and current setting of 0.4 Amps. Letter is enclosed as Annexure-II. Members may deliberate C.3.2 Tripping of ICT’s at 400/220kV Bamnauli substation at 17:35 hrs.on 20th January 2012. ICT's at 400/220kV Bamnauli substation (DTL) had tripped during the event. Load on all four ICT was 580 MW. Fault was cleared in 900 ms as seen from Dadri PMU voltage plot. As reported, un-

cleared fault in 220kV Bamnauli-Najafgarh line had led to these tripping. From SCADA SOE available at NRLDC, it was observed that the breaker of 220kV Bamnauli-Najafgarh line had not opened from bamnauli end. Also it was seen from SOE that ICT-2 & ICT-4 had tripped during the incident. Further investigation is required for non-operation of LBB for 220kV Bamnauli – Najafgarh line-1 at Bamnauli end, non-tripping of remaining ICT-1 & ICT-3. DTL has submitted a report via e-mail. The copy of same is enclosed as Annexure-III. Members May Deliberate C.3.3 Generation loss at Tehri HEP & Koteshwar HEP at 23:40 hrs. on 6th January 2012. 400kV Koteshwar HEP-Koteshwar pool ckt-1&2, 400kV Tehri HEP-Koteshwar pool ckt-1&2 lines along with running units at Koteshwar & Tehri HEP had tripped during the incident. Generation loss of 400 MW had occurred due to tripping of Units at Tehri & Koteshwar HEP. In 72nd OCC meeting, representative of THDC had informed that machine tripped due to over voltage. As the events could not be corroborated with the explanation given by THDC, OCC had requested THDC to submit a detailed report of the event. Report is awaited. Concerned agency (THDC) may appraise PSC about the findings. C.3.4 Multiple tripping and generation loss at Salal HEP at 23:14 hrs on 6th January 2012. Running unit #4, 220kV Salal-Jammu ckt-1&2 and 220kV Salal-Kishenpur ckt-1, 2, 3 & 4 had tripped during the incident. It was reported that Bus-bar protection had operated at Salal HEP. Similar incident of complete outage had occurred at Salal HEP on 8th and 11th May 2011. Representative of NHPC had informed in 72nd OCC meeting that all outgoing lines from Salal had tripped on over-voltage. Concerned agency (NHPC) may appraise PSC about the status of healthiness of EL & DR at Salal HEP. Detailed investigation report is awaited from NHPC. C.3.5 Complete outage of 400/220kV Allahabad (P.G) Substation at 5:39 hrs.on 14th January 2012. a) Brief about LBB scheme : Basic breaker failure protection provides a means to trip adjacent current sources if a fault is detected by protective relays and the associated breaker(s) fail to interrupt the fault. Figure: 1 is a logic diagram showing a basic breaker failure scheme.

Figure 1 : Basic Breaker Failure Scheme

Two conditions are used to monitor proper breaker operation during a fault clearing operation. These are: 1) the presence of current flow in the breaker (50BF) and 2) a protective relay trip signal (BFI). It is construed that the breaker has failed to operate properly if both of these signals are present for a period greater than the expected breaker clearing time. A delay on pickup timer (62-1), with a time delay setting that exceeds the breaker normal clearing time, is used to determine successful operation of the breaker. If the breaker operates properly, either one or both of the 50BF or BFI inputs will de-assert and stop operation of the timer.

b) Brief about 400/220kV Allahabad (P.G) substation tripping and points to be discussed in PSC 400kV Allahabad-Sarnath, 400kV Singrauli-Allahabad ckt-1&2, Rihand-Allahabad ckt-1&2, Allahabad-Mainpuri ckt-1&2, 400kV Allahabad-Sasaram, 400kV Allahabad-Kanpur ckt-2, 400kV Allahabad- Fatehpur ckt-3 had tripped during the incident. As reported the breaker of 400kV Allahabad-Sarnath line was under lockout at 400kV Allahabad (P.G) end. The triggering incident of fault was flashover in isolator connecting 400 kV Allahabad-Sarnath line with BUS-1 at Allahabad. This flashover occurred while opening isolator in charged condition (Main circuit breaker of this line was under lockout). This resulted into a fault which led to tripping of all feeders from 400/220kV Allahabad(P.G) substation. Representative of POWERGRID had said in 72nd OCC meeting that LBB could not operate due to peculiar behaviour of the relay. Distance protection relay for Allahabad end lines gave continuous command for 154 m-sec but LBB operations requires 200 m-sec for it operation. Again distance relay gave command to LBB for operation but timing of command was less than 200 m-sec because of which LBB could not operate. All lines connected to Allahabad tripped in Zone-2 i.e. around 500 msec. Third time relay had picked up for 217 m-sec and this time LBB operated. Due to non-operation of main-1 protection for more than 200 m-sec, Bus-Bar protection could not be operated. The matter of peculiar behaviour of relay was referred to ABB by POWERGRID and it was said that response from ABB was awaited. a. It was decided in 72nd OCC meeting that the matter would be discussed Protection sub-Committee. POWERGRID may appraise PSC about findings. b. 400kV Singrauli-Allahabad Ckt-1& 2 tripped from Singrauli STPS end within 100ms of occurrence of fault. This Protection operation at Singrauli end needs investigation. NTPC may appraise PSC about the findings C.4 The following additional trippings had occurred which may be discussed C.4.1 Tripping of ICT's at 400/220kV Muradnagar Substation (UPPTCL) on 12th February 2012 at 10:20hrs As reported fire in 220kV side CT of 400/220kV ICT-1 led to tripping of ICT-2 & ICT-3 at 400/220kV Muradnagar Substation. The concerned agency (UPPTCL) may appraise the PSC and forward the detailed analysis report to NRPC/ NRLDC along with the printouts of DR/EL C.4.2 Generation loss at Dadri TPS at 17:40 hrs on 13th March 2012 All running units of Dadri generation complex (except GT#4 of Dadri GPS) tripped causing generation loss of 2650 MW. HVDC Rihand Dadri Bipole also tripped during the event. The SPS of HVDC Rihand-Dadri had operated causing generation reduction in Singrauli/Rihand STPS and load shedding in Western part of NR. As per Fax message received from NTPC on 14th March 2012

i. Earth switch remain closed while restoring back 400kV Bus-2 after shutdown. ii. Bus-Bar protection of 400kV Dadri 400kV bus-1 operated due to zero time

delay in LBB relay. This caused outage of entire station iii. Fault current recorded was 53 KA

Following may be appraised to and discussed by the committee:

a)The concerned agencies (NTPC/POWERGRID) may appraise the PSC and forward the detailed analysis report to NRPC/ NRLDC along with the printouts of DR/EL. b)Constituents (NTPC/Powergrid/UPPTCL/BBMB/PSTCL/DTL/RRVPNL) may forward automatic Generation backing down & load shedding details due to SPS operation in SPS monitoring format as given in N.R operating procedure and forward the same to NRLDC. c)Methods to be explored to avoid Bus charging with Earth Switch. Members may share their views/opinion on the following :

i. Devising Interlocks ii. Training of workforce iii. Compliance to protocol/procedures

C.4.3 Generation loss, load loss and tripping of 220kV lines in Delhi system on at 19:08hrs on 3rd April 2012 Tripping of Pragati Gas units 2&3, Rajghat TPS units 1&2, tripping of 220kV mandola-wazirabad ckt-1, 2,3&4 had occured during the incident. Generation loss of 300 MW and load loss of 700MW occurred during the incident. DTL had sent a report. However no D.R/E.L print was enclosed with the report. According to report, conductor snapping had occurred in 220kV Madola-Wazirabad ckt-4 & 220kV Mandola-Wazirabad ckt-3 also tripped as the snapped conductor had fallen on this line which led to their tripping. 220kV Mandola-Wazirabad ckt-1&2 had tripped from Mandola end on distance protection. This led to islanding of Pragati and RPH units and later their tripping. Following points need further investigation:

a. Distance protection had not operated at Wazirabad end for 220kV Mandola-Wazirabad ckt-3.

b. Tripping of 220kV Mandola-Wazirabad ckt-1&2 from Mandola end as the fault was in 220kV Mandola-Wazirabad-ckt-3&4.

The concerned agency (DTL/POWEGRID) may appraise the PSC about the findings. C.4.4 Tripping of 400kV lines and ICT's at 400/220kV Azamgarh (UPPTCL) substation on at 00:43hrs on 4th April 2012 400kV Azamgarh-Sultanpur, 400kV Azamgar-Gorakhpur(UPPTCL), 2 No. ICT's at Azamgarh Substation tripped during the incident. Triggering incident was reportedly failure of CT at Azamgarh Substation. The concerned agency (UPPTCL) may appraise the PSC and forward the detailed analysis report to NRPC/ NRLDC along with the printouts of DR/EL. C.4.5 Tripping of 400kV lines and load loss in U.P Load loss 01:27 hrs on 02nd April 2012 400kV Dadri-G.Noida, Ballabgarh-G.Noida, 3x315MVA 400/220kV ICT's at G.Noida tripped during the incident. Load loss in U.P was approximately 400MW. NTPC,Dadri had sent a preliminary report in which it was said that failure of R-Phase L.A of 400kV Dadri-G.Noida line occurred at Dadri end. Line auto-reclosed but tripped due to sustained fault. Point which need further investigation: a. Tripping of ICT’s at Greater Noida b. Tripping of 400kV Ballabgarh-G.Noida line

The concerned agencies (UPPTCL/POWERGRID) may appraise the PSC and forward the detailed analysis report to NRPC/ NRLDC along with the printouts of DR/EL. C.4.6Tripping of 400kV lines & Generation loss RGTPP, Khedar at 10:12 hrs on 5th April 2012 Tripping of 400kV Khedar-Kirori ckt-1&2, 400kV Khedar-Fatehabad ckt-1&2, running units at RGTPP (Khedar) occurred during the incident. Generation loss of 1130MW had occurred at RGTPP, Khedar. As reported triggering incident was operation of Busbar protection at 400kV Khedar (HVPNL). The concerned agency (HVPNL) may appraise the PSC and forward the detailed analysis report to NRPC/ NRLDC along with the printouts of DR/EL.

Details of Relays Settings for Transmission Lines Annexure-I

S.No

Description of line (example)

Name of protection relay(Model/Ma ke)

Parameter of line and Type of conductor

Zone Settings

Features Enable in the Relay & their Details

Parameter(R, Xl, Xc, Conductance, Length)

Type & Configuration of conductor

FFR Power Swing Blocking

Carrier Scheme

B/U Over Current Function

B/U Earth Fault Function

SOTF Broken Conductor

A/R Stub Protection

Over- Votage Protection

1 400KV Dadri-Mandola-I Mandola end:

Zone 1 Operation Operation Operation

Operation Operation Operation Operation Operation Operation

e.g. Main-I: REL670 (ABB make)

Reach(%)

ON/OFF ON/OFF

PUR/POR/PBR ON/OFF ON/OFF ON/OFF ON/OFF ON/OFF ON/OFF ON/OFF

400KV Dadri-Mandola-I Mandola end:

Time sett.

Op. Mode First Stage First Stage

time delay for alarm / trip: ....sec

Mode:

I> %Ibase Stage-1 U1>% volts

Zone 2 Zero seq In case of Blocking Scheme; Relay coordination time.... ms

Dir. Mode: OFF/ Non-Direct./FWD/REV

Dir. Mode: OFF/ Non-Direct./FWD/REV

U< % Ubase 1PH/3-PH/ Stage-1 time delay: ....sec

Reach(%)

3U0>%Ubas e I>%Ibase Dead time:.... sec Stage-2

U2>%volts

Time sett. 3I0< %Ibase Blocking zones:Z1,

Z2, Z3 IDMT IDMT Reclaim Time:

.... sec Stage-2 time delay: ...sec

Zone 3 VTS time delay-.... Sec I1 (PMS)-

...%In In1 (PMS)-....%In

Reach(%)

Un-blocking time delay...sec

t1 (TMS)- ...

t1 (TMS)-

Time sett.

Zone 3® Second

Stage Second Stage

Reach(%) Dir. Mode:

OFF/ Non-Direct./FWD/REV

Dir. Mode: OFF/ Non-Direct./FWD/REV

Time sett. Definite time

Definite time I2- ....Amps In2-.... Amps t2(definite

time delay)-....sec

t2(definite time delay)....sec

e.g. Main-II: MICOM (AREVA make)

A^^ LRur\& d

IF./n3./13 1t:IT HF Ll1:lEFl,jET F.:rlt', F . I:II

Wf-}I.'}'ICfi O1.' T'HE CHII'F t:.N{;TNIi!]R

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.20J:

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S Lr l-'(- ;, rt L'tldinu Enp irtecr t tJpuration )

Irfot':ctior] Sth..L'otn rn itte:c

NcrthernR ralPou'et'{lt:r:rirtiltecl8 - A. Salrecd Jcu't Sir:gh \rall,,.Kat$,aria Sarai. licrv Dclhi - ! i(i(JlbFn.t No. - (01 Ii 16365liltrc "gllil : r[pgi:.l t{:iJ .i i!ti.li; il i;]i.' ii : i.. .lr,:L',

SiL.

it is trr inlbrm vou that ilrcrc was simultancous rrrpping oi'all the rh:'ce utiits oi'

3X210 fu{',v i:i"Anpnra 'A"I'PS at 20.25 hr of 0?.12,20i1 operation of CT Neutrl! 0/clelar,s (5lN'I't air"r trinpin,.l ot'400tlV Anpara * ['1ar.r on line fault in its seconci u-one

rron Anpara encl iirmilar nrnnl u'ippin,ss of ail th+. iirrc; ttnits of .Anpara 'A'"I'PS. huve

'. .'rlltrr-d lthcnevr:r rhere rlr-., ireavv i'auits on 4{i(}Klt' iines and their fault cleare<l li'otni "ir- .ir-'.. .rq1d Or thlrd in pt'r'r'lt:u:; i'ears.

At Anpara 'A'1'P5. -rlN'l rclal on all tttr*r units iustalied (at HV side of neutral

ol'G'l') are of lDi','l'f t-v-pe iiaving plug setiillg oi 0,1 Arnp. at''d TMS 0.45. Rrtlef is

eleclronreclranrcal typor, n'ir:rlcl 'l'.lr i'10. lllil':s- f:astttt Revrclle. GT riltillg-250h,1VA,I 5.?i!/420K'ii, inlpe,inncc- i r'ib. C i' ii;rtic-5t)0/lAntp. Il.clay characteristic

curvs gl'51N], |I)il,l't'i:t crrsioricd lor rcfcrcnce. Considering 100 % fault surrcltt

{2148i\nrp.) . plug serting {)l'5lN't'shoulcl he nearto 10r;i: of CT secondary tauh currcnt'i,e.0.4-] r\mp. While lt glrl::,,.i.Ir pitig sctling of rnstalled relat'is 0.1 Anrp. due to whichSlNT'rclav trrfipflrl {i'I's r,rirru rrinro \r,/as hra\il: l'llrtlt tn "lf}flK\t tr:lnsmission liner and

delayecl tniriripg <tl'iilrcs nfl z'-ntii: :.ec(]i'r{J or thitct f:rim Ani,'ara end.

,,\ rnecting le$a,.'ci;ug {riirilrl'l.g oi'all three units of ,{npal" 'A'TPS u'ere held '..'iiit{ihieI Enginc.er. Plivel'5\'$tc!u. t.lPP'l'CL, l..ucknou'on 10.0?.2012. ln this meeting it ri'as

cleci,lecl tilat frrqueit ir;r ilr.str i'erxluriitendatiorts of setilug of 5ti{t. IDMT relavs ttl',,\.np.:ra'".\'fi)S k,,:cl-ring in ,.i*$ rri lettings crl' tt*.ttbv pot\'rr st;iiions and changr:d

scr.nafic.r o,- ,gr:d. ',rr(ririrJ Lrr .',irnl ro '!)fotect]oq SLltliji:)ill:titree' oi' NRPC.(\4O['l ofi; icci iittr. r tt(:ltt;ri:r"i ;.

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:::T::::::l .r:ris:ping :il Arlpi,r a r i{l i{} r,{w r:nirs

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Annexure-III Reply to 73rd OCC Agenda Point No. 4 (viii). ICT’s at 400/220KV S/Stn. Bamnauli tripped during the event at 17:35 Hrs. on 20th of

Jan. 2012. OCC has asked DTL for detailed investigation and report on the

incident. Before the event all the ICT’s were running in parallel with all the bus

coupler and bus section closed. The fault was on bus side of CT of 220KV Najafgarh

Ckt.I. This was a bus fault and bus bar protection should have detected the fault. It

is always not possible to check the bus bar protection in detail due to load

constraints. The reason of non operation of the bus bar protection was investigated

and it was observed that the bus bar protection could not operate due to faulty

power supply cards. Spare cards for the Static version of Alstom Make bus bar

protection type PBLSB are being arranged and the scheme will be rectified very

soon. As the fault was not cleared instaneously by operation of the main

protection i.e bus bar protection, it was supposed to be cleared by tripping of the

I/C breaker of all the ICT’. The two I/C’s tripped within 850 ms and the remaining

two ICT’s were also supposed to be tripped around the same time. But before

these two ICT’s could have tripped the fault was cleared by tripping of the breaker

of faulty Najafgarh Ckt.I Bay and as such no further tripping were required. The

relays of the two I/C’s have been tested and found to be working satisfactory.

All the 220KV feeders emanating from 400KV S/Stn. Bamnauli tripped from the

remote end either on directional earth fault or distance protection. From the

remote end Disturbance records it is revealed that the zero sequence current

measured at the remote end was around 300 to 400 Amps and the voltage

recorded at the remote end was around 9KV which is very likely in case of the bus

fault where the voltage has been recorded to reach very low value. The DR of the

remote end relays and SOE of the event are enclosed for reference please.

(Er. B.L Gujar ) Manager (T) Prot. II

DGM (Prot.& Metering)