SOUTHERN REGIONAL POWER COMMITTEE BANGALORE

Transcription

1

2 SOUTHERN REGIONAL POWER COMMITTEE BANGALORE Minutes of the 25 th Meeting of Protection Coordination Sub-Committee of SRPC held on Introduction 1.1 The 25 th Meeting of Protection Coordination Sub-Committee (PCSC) was held on 22 nd October 2013 in the Conference Hall of Southern Regional Power Committee, Bangalore. The list of participants for the PCSC meeting is enclosed as Annexure-I. 1.2 Shri S. R. Bhat, Member Secretary i/c, SRPC welcomed the Members and Participants to the 25 th Meeting of the Protection Coordination Sub- Committee. 1.3 MS i/c, SRPC informed the forum that the issue regarding high voltage trippings had been discussed in the recent meeting of OCC and PCSC and few recommendations had been suggested for implementation. Though the constituents were requested to revert back in case of specific issues, no feedback had been received from any of the constituents. He also informed the forum that swapping of voltage settings on 400 KV Kaiga- Guttur lines had been carried out as suggested in the last PCSC meeting. 1.4 MS i/c stated that there needed to be a proper mechanism to follow up on the recommendations made in earlier Meetings. The endeavor should be to have logical conclusion for every critical tripping incident. This would happen only when the identified measures are implemented in a time bound manner. 1.5 MS i/c informed that Unit 1 of Kudankulam Nuclear Power Plant had now been synchronized and hence the proposed SPS needed to be finalized. SRLDC had already furnished the study results to NPCIL but the response was awaited.he also stated that the fortnightly reports on implementation of measures as submitted by the constituents were being perused by higher level bodies. Hence the recommendations as suggested by the protection coordination committee and the other subcommittee needed to be given

3 more focus and carried out on priority basis. He also noted that as per earlier decision, TANTRANSCO was to complete the islanding scheme by October MS i/c SRPC requested the constituents to furnish the status of implementation of pending issues and accordingly the same was taken up for discussion. 2. Confirmation of the Minutes of the 24 th Protection Coordination Sub-Committee meeting held on 26 th September, 2013 The Minutes of the 24 th PCSC meeting were confirmed, since no comments were received from the constituents. 3. Grid Disturbances in Southern Region 3.1. Generation loss & tripping of 220kV lines at Kothagudam TPS and Tripping of ICT s at Khammam substation (i) Date and Time of event (ii) Location (iii) (iv) Plant and/or Equipment directly involved Reported Disturbance / Fault at Hrs Kothagudam TPS,Khammam ICTs, Andra Pradesh Kothagudam TPS, Khammam ICTs Triggering incident was a fault in 220kV KTPS-Managuru line-1. Running Units # 1, 2,3,4,5,6,8,9&10 tripped. 220kV lines connected to KTPS tripped on Zone-2 from remote ends. ICT s at Khammam tripped on overload. Frequency dropped from Hz to 49.71Hz (v) Generation Loss 1100 MW (vi) Duration of interruption 30 Minutes to 6 Hrs 15 Minutes (vii) Category GD 1 The Grid Disturbance analysis as submitted by SRLDC is enclosed as Annexure-II. The Grid Disturbance Report as submitted by APTRANSCO is enclosed as Annexure-III. SRLDC informed the forum that data pertaining to this incident had not Minutes of the 24 th Protection Coordination Sub Committee Meeting held on Page 2

4 been posted by APGENCO and APTRANCO for detailed analysis of the Grid Disturbance. APGENCO informed that at Kothagudam TPS one unit was under planned shutdown and another unit tripped on Generator overload. APGENCO informed that a jumper got cut on the terminal tower at Kothagudam Thermal Power Station (KTPS) end resulting in arcing followed by phase to ground earth fault. It was informed that 3 to 4 jumpers of CVT and other equipment got cut after jumper cut on terminal tower. The CB however did not trip since there was a contact problem with master trip relay. The faulty relay had been replaced with new one. At the same time at remote end, one pole opened while the other poles did not open leading to LBB/BB operation. It was noted that LBB had not initiated at KTPS end though the relay was faulty. It was informed that 132kV system at KTPS got tripped due to low vacuum in the CB. APGENCO said that GT-4 at generator end tripped on O/L and GT-3 tripped on back up O/C. SRLDC pointed out that it was a case of relay mal-operation. NTPC stated that the load was thrown off due to line tripping. AVR had to take care of the voltage issues of the Generator so that generator did not trip on over voltage. SRLDC enquired about the setting of IDMT characteristics for ICTs in SRTS-I of PGCIL. PGCIL informed that adjoining utilities should also follow CBIP guidelines. It was noted from PGCIL that the existing setting of 380 ms for DTOC would be increased to 500 ms pending instructions from their management regarding adoption of IDMT settings for ICT. KPTCL requested POWERGRID to share its Protection settings with the adjoining utilities for better protection coordination of the SR System. They were also ready to share their settings with the adjoining utilities. SRTS I, PGCIL was requested to adopt only IDMT settings for ICTs in all its substations. The DTOC settings could be removed latest by and information submitted to SRPC Secretariat. Minutes of the 24 th Protection Coordination Sub Committee Meeting held on Page 3

5 Recommendations a) APTRANSCO and APGENCO were requested to send the detailed analysis report of the above incident at the earliest. b) PCSC forum also requested all the constituents to submit grid disturbance report at the earliest to analyze the Disturbance / Incident to avoid similar occurrence. c) PCSC forum requested the utilities to share their protection settings with the adjoining utilities also for better protection coordination and to avoid in spurious trippings. d) Due to lack of proper incident report, Protection coordination Sub Committee decided to send the Protection Expert Group (5 Members) to visit KTPS substation in November 2013 after analyzing the Grid disturbance report to be sent by APGENCO. e) SRTS I, PGCIL to adopt only IDMT settings for ICTs in all its substations. 3.2 Generation loss and multiple tripping at Vijayawada TPS (i) Date and Time of event (ii) Location Plant and/or Equipment (iii) directly involved (iv) Reported Disturbance / Fault (v) Generation loss (vi) Duration of interruption (vii) Category at 14:55 hrs Vijayawada TPS,APGENCO,AP Vijayawada TPS As reported that triggering incident was B Phase CT failure in 220kV VTPS- Narasarapeta line. Running Units # 2,3,4,5 &6 and all 220kV feeders connected to Vijayawada TPS tripped on operation of Bus bar protection. Frequency dropped from Hz to 49.62Hz 900 MW GD1 The Grid Disturbance analysis as submitted by SRLDC is enclosed as Annexure-IV. The Grid Disturbance Report as submitted by APTRANSCO isenclosed as Annexure-V. SRLDC informed that the tripping analysis report had not been received by them to analyze the Grid Disturbance. APTRANSCO informed that 'B' Phase CT had failed in the VTPS- Narasarapeta line. Minutes of the 24 th Protection Coordination Sub Committee Meeting held on Page 4

6 Recommendations a) APTRANSCO and APGENCO were requested to send the detailed analysis report of the above incident at the earliest. b) The Disturbance would be discussed in the 26 th PCSC. 4. Grid Incidences 4.1 Tripping of Unit#1 at North Chennai TPS ST2 (i) Date and Time of event (ii) Location Plant and/or Equipment (iii) directly involved Reported Disturbance / (iv) Fault (v) Generation loss (vi) Duration of interruption (vii) Category at 14:50 Hrs North Chennai TPS ST2,TN North Chennai TPS As reported Unit#1 tripped due to operation of differential protection of Unit# MW GI2 TANTRANSCO informed that since the plant had not yet been formally handed over to them, it was difficult to get the report from the plant. It was noted that there was a CB problem and M/s Areva had attended the same. TANTRANSCO informed that the plant was still under outage and its COD too was not yet declared. SRLDC stated that the relevant tripping details should be made available to it, as per Regulations. Recommendations a) TANTRANSCO was requested to send the detailed analysis report of the above incident at the earliest. b) The Grid Incidence would be discussed in the 26 th PCSC. 4.2 Tripping of HVDC Badrawathi Pole - 1 & 2 (i) Date and Time of event (ii) Location Plant and/or Equipment (iii) directly involved (iv) Reported Disturbance / Fault at 16:26 Hrs HVDC Badrawathi, PGCIL,AP HVDC Badrawathi As reported tripping occurred due to auxiliary supply failure. Frequency dropped from Hz to Minutes of the 24 th Protection Coordination Sub Committee Meeting held on Page 5

7 (v) Generation loss (vi) Duration of interruption (vii) Category 49.28Hz 1000MW 17 Minutes GI2 It was informed that failure of auxiliary power supply to HVDC station was the cause of tripping. Concerns were raised over the absence of redundancy of auxiliary supply. SRLDC queried about status of installation of 315 MVA ICT. ED, SRLDC stated that system operator should get the complete tripping reports as per IEGC guidelines. He also informed that SRLDC may not be in a position to certify the availability certification for the interregional links for the above said period with out getting the complete tripping reports. Recommendations a) PGCIL was requested to send the detailed analysis report of the above incident at the earliest. b) The Grid incidence would be discussed in the 26 th PCSC. 4.3 Tripping of Unit#7 at Raichur TPS & 400kV BTPS-Raichur line (i) Date and Time of event at 05:49 hrs (ii) Location Raichur TPS, KPCL, Karnataka (iii) Plant and/or Equipment directly involved Raichur TPS (iv) Reported Disturbance / Fault (v) Generation loss 210 MW (vi) Duration of interruption (vii) Category GI2 As reported fault had occurred in Generator transformer of Unit#7 at Raichur. The tripping of 400kV BTPS-Raichur line on Zone-2 from BTPS end needs to be further investigated It was noted that a fault indication was sensed on RTPS- BTPS line. At RTPS end fault indication was in zone 1 while at BTPS end it was in Zone 2 for RTPS Unit 7 GT Failure. SRLDC pointed out that line protection should not operate for GT fault. It was reported that GT has failed and no D/R was sent within the stipulated time. Minutes of the 24 th Protection Coordination Sub Committee Meeting held on Page 6

8 Recommendations a) KPCL was requested to send the detailed analysis report of the above incident at the earliest. b) The Grid incidence would be discussed in the 26 th PCSC. 5. Status of Pending Protection issues The following pending protection issues were discussed in the 25th PCSC meeting. SN Recommendation The meeting in which the issue was Discussed 1 The Main I and Main II Protection of Different make- Sharavathy 2 Replacement of OLD CBs at Sharavathy 3 COMPLIANACE OF 3RD PARTY AUDIT REPORT- Sharavathy 4 BUSBAR PROTECTION AT KAYATAR 110KV SUBSTATION 21st PCSC held on st PCSC held on th PCSC - 25th PCSC ( to ) 21st PCSC held on Anticipated date of completion Agency Status 25 th PCSC Dec-13 KPCL Pending KPCL informed that the protection issue would be sorted within the agreed time. Dec-13 KPCL Pending KPCL informed that the protection issue would be sorted within the agreed time. Dec-13 KPCL Pending KPCL informed that the protection issue would be sorted within the agreed time. Dec-13 TANTR ANSCO Pending TANTRANSCO informed that the protection issue would be sorted within the agreed time. 5 Thermo vision Scanning of Jumpers 6 PROVIDING DR AND EL- MAMIDAPALY 22nd PCSC held on rd PCSC held on Dec-13 Dec-13 TANTR ANSCO APTRA NSCO Pending Pending TANTRANSCO informed that it is an operational issue and requested PCSC forum to put it in the operational agenda.the forum agreed for the same. APTRANSCO informed that the protection issue would be sorted within the agreed time. Minutes of the 24 th Protection Coordination Sub Committee Meeting held on Page 7

9 7 EARTH PITS at EDAMON 8 DG SET NOT AVAILABLE- EDAMON 9 48 V DC SUPPLY REDUNDANCY NOT AVAILABLE- EDAMON 10 ONLY ONE BUS IS AVAILABLE, TRANSFER BUS SHALL BE PROVIDED - EDAMON 11 CARRIER INTERTRIPPING IS NOT AVAILABLE FOR SBEM 1,2,3 FEEDERS- EDAMON 12 MAIN2 DISTANCEPROT ECTION FOR EMPC#1 FEEDER NOT AVAILABLE- EDAMON 13 LBB NOT IN SERVICE FOR SBEM 2,3 AND EMPC#1-EDAON 14 IDMT characteristics for Earth Fault Relay of the GTs in UPCL 15 UPCL -Kemar Line Protection would be coordinated by KPTCL and UPCL 17th PCSC ( ) 17th PCSC ( ) 17th PCSC ( ) 17th PCSC ( ) 17th PCSC ( ) 17th PCSC ( ) 17th PCSC ( ) 24th PCSC ) 24th PCSC ) Mar-14 KSEB Pending KSEB informed that the protection issue would be sorted within the agreed time. Nov-13 KSEB Pending KSEB informed that the protection issue would be sorted within the agreed time. Dec-13 KSEB Pending KSEB informed that the protection issue would be sorted within the agreed time. Mar-14 KSEB Pending KSEB informed that the protection issue would be sorted within the agreed time. Nov-13 KSEB Pending KSEB informed that the protection issue would be sorted within the agreed time. Nov-13 KSEB Pending KSEB informed that the protection issue would be sorted within the agreed time. Nov-13 KSEB Pending KSEB informed that the protection issue would be sorted within the agreed time. Nov-13 UPCL Pending UPCL and KPTCL were requested to coordinate and change the relay settings. Oct-13 KPTCL /UPCL Attended KPTCL and UPCL checked the relay settings to avoid trippings like incident. Minutes of the 24 th Protection Coordination Sub Committee Meeting held on Page 8

10 16 Reviewing of Distance Protection relay settings at Hassan by PGCIL SR II 24th PCSC ( ) Oct-13 SR II, PGCIL Attended Distance Protection relay settings at Hassan was coordinated by PGCIL SR II 17 NPCIL and KPTCL in coordination to review the protection settings at Kaiga 18 Modification of the present breaker tripping scheme of Haveri line-2 so that the trip coils are activated through two different DC sources 19 The non availability of 220 KV and 400 KV bus coupler is affecting the reliability of 400/220 KV Guttur Substation 20 Relay/CVT error in 400 KV Kaiga-2 Line 21 The non tripping of breaker at Pondy SS would be checked for NLC tripping 24th PCSC ( ) 24th PCSC ( ) 24th PCSC ( ) 24th PCSC ) 23rd PCSC held on Nov-13 KPTCL Pending Kaiga,NPCIL and KPTCL were requested to coordinate and change the relay settings. Dec-13 KPTCL Pending KPTCL informed that the protection issue would be sorted within the agreed time. Oct-13 KPTCL Pending KPTCL informed that the protection issue would be sorted within the agreed time. Oct-13 KPTCL Attended KPTCL informed that the protection issue was sorted out. Oct-13 NLC Attended NLC informed that the protection issue was sorted out. The PCSC forum requested the constituents to implement the above protection committee recommendations on priority basis. 6. SPS for Kudankulam Nuclear Power Station SRLDC brought to the notice of the PCSC forum that therehad been re-orientation recently in respect of 400 KV lines emanating from Kudankulam. Three 400kV lines were now from Kudankulam to Thirunelveli while remaining one line is from Kudankulam to Madurai. Hence the following logic was proposed for SPS at Kudankulam on account of the change in the configuration: Minutes of the 24 th Protection Coordination Sub Committee Meeting held on Page 9

11 Contingency Tripping of all three lines from Kudankulam to Thirunelveli and two units in running condition at Kudankulam. Action One unit at Kudankulam to go on house load and the second unit generation would be evacuated through 400kV Kudankulam- Madurai line. 25 th PCSC The PCSC forum requested KKNPP, NPCIL to send the detailed analysis report about the SPS and modifications if any in the SPS as suggested by SRLDC latest by Review of Power swing block settings of Distance protection relay PCSC forum decided that the issue would be discussed in detail by the Sub Group Meeting to be held on (Wednesday) preceding the PCSC meeting. Issues relating to Over voltage and staggered tripping and any other Protection relay setting issues may please be sent to the SRPC Secretariat latest by to have fruitful discussions in the Sub Group meeting of PCSC. 8. Compliance status of Protection Audit conducted in the Substations of Southern Region PGCIL informed that regarding Munirabad SS the issue was taken up with KPTCL. KPTCL informed that that Main-1 and Main-2 relays have been included in the DPR but however for the same tender has also been called for. 9. Tripping Incidents in the Southern Region The trippingdetails that had occurred in the Southern Region during the month of September - October 2013 is attached herewith as Annexure-VI. Constituents were requested to update the details in the SRLDC Website at the earliest to analyze the incidents and suggest remedial measures if any. Minutes of the 24 th Protection Coordination Sub Committee Meeting held on Page 10

12 10. SPS for 400 KV Kolar - Hosur line SRTS II, PGCIL informed that the Original Equipment Manufacturer (OEM, i.e. Siemens) had advised against having too many Logics (in this instancerunback) in the HVDC system. It was agreed that the SPS for 400 KV Kolar-Hosur Line would be discussed in a Special Meeting to be convened at Kolar SS. 11. Status of implementation: SPS in Southern Region S N Name of the Scheme 1 Proposed Modification in the SPS at Kolar SS Details of the scheme In the 16 th PCSC the forum proposed an additional trip logic (dp/dt )to the Kolar SPS during contingencies similar to New Grid disturbance on Impleme nting Agency PGCIL 25 th PCSC PGCIL informed that the SPS is under Process. Would be completed by end October PCSC Recommendations The forum requested PGCIl to complete the modification within the agreed time. 2 Kudankulam SPS 3 Modification in NTPC Talcher SPS In case of tripping one or two units at Kudankulam nuclear power plant, trip signal-1 or Trip signal-1&2 will be generated depending on number of units tripping. Trip signal-1:793 MW and Trip Signal-2:710 MW SPS would be modified to back down all the generating units instead of tripping the units PGCIL NTPC Second Mock Exercise was conducted on 29 th August New Scheme with SPS 1000 may be kept in service under normal Operating conditions The PCSC forum requested NLDC/SRLDC to convey the decision at the earliest. 12. Status of implementation: SPS in Andhra Pradesh S N Name of the Scheme 1 Vijayawada- Nellore SPS Details of the scheme if one of 400kV Vijayawada- Nellore D/C line trips and before tripping flow each circuit is >550 MW then back down generation or trip one generating unit each at GMR Vemagiri, Gouthami, Konaseema, Jegurupadu-II and Lanco. Total generation back down of 430 MW. Proposed in 9th PCSC ( ) Impleme nting Agency PGCIL./ APTRA NSCO/IP Ps 25 th PCSC PGCIL informed that the SPS would be completed by 10 th November PCSC Recommendations The PCSC forum decided to conduct mock exercise on 30th November Minutes of the 24 th Protection Coordination Sub Committee Meeting held on Page 11

13 2 Nellore-Almatti SPS If one of 400kV Nellore-Almatti DC line trips and before tripping flow each circuit is >520 MW then trip one generating unit each at SEPL and MEPL. Total generation back down of 300 MW. Proposed in 15th PCSC ( ) PGCIL MEPL sent the confirmation. The PCSC forum decided to conduct mock exercise on 15th November 2013 at 12:00 Hrs. APTRANSCO was requested to coordinate the Mock exercise with IPPs. 13. Status of implementation: SPS in Karnataka S N Name of the Scheme 1 Somanahally& Bangalore water supply Details of the scheme a) To trip all 220kV lines & 220 / 66kV trfs except 220 kv Harohalli & Tataguni lines at Somanahally and to trip Vrishabhavathi line at Tataguni when ICTs at Somanahally trip. b) To trip 220 kv Vajamangala and Madhuvanahally-1 & 2 lines at TK Hally when ICTs at Mysore trip. Impleme nting Agency KPTCL 25 th PCSC KPTCL informed that the Substation feeding configuration. KPTCL is modifying the logic as per the latest configuration. PCSC Recommendations The PCSC forum requested KPTCL to submit the SPS Logic to the SRPC Secretariat. 14. Status of implementation: SPS in TamilNadu S N Name of the Scheme 1 Thirunelveli SPS Details of the scheme To avoid overloading of Thirunelveli ICTs in the contingency of tripping of Thirunelveli-Edamon lines. 2 Madurai SPS To avoid overloading of Madurai ICTs. Impleme nting Agency TANTR ANSCO TANTR ANSCO 15. Implementation of Islanding schemes in SR 25 th PCSC TANTRANSC O informed that the scheme was implemented on TANTRANSC O informed that the scheme would be ready by end of October PCSC Recommendation s The forum requested PGCIL / TANTRANSCO to send the scheme details (Logic and SLD) to SRPC Secretariat latest by The forum requested TANTRANSCO to implement the scheme within the agreed time. The PCSC forum requested TANTRANSCOto implement the remaining part of Stage II of the Islanding Scheme latest by end of October 2013 since other utilities had completed their part.. TANTRANSCO agreed to complete their part by the agreed time line. Minutes of the 24 th Protection Coordination Sub Committee Meeting held on Page 12

14 16. The issue of AUFR stages and implementation in SR In the second NPC Meeting, ithad been agreed that there would be four stages for AUFLS starting with 49.2 Hz. The various stages for AUFLS operation are 49.2 Hz, 49 Hz, 48.8 Hz and 48.6 Hz. It was noted that all the stages had been implemented except portion of the last stage of 48.6 Hz in TN. 17. Submission of completed dynamic study data All SLDCs were requested to direct the embedded IPPs connected at 220 KV and above voltage level to submit completed dynamic study format to SRPC, Secretariat. NPCIL, MAPS was requested to submit the dynamic study data of their system. 18. Synchronizing facility for Black start restoration The PCSC forum requested KPTCL to provide synchronizing facility in Hubli S/S within the agreed time (i.e. by August 2014 ). 19. Requirement of Under Voltage Relays (UVR) for SR The PCSC forum had proposed for the provision of under voltage relays in various low voltage pockets to ensure reliable power supply and grid safety Constituents were requested to install the UVR at least in a phased manner in the SRLDC specified nodes. Progress in this regard may be reported to the PCSC forum at the earliest. 20. Implementation of recommendations of Grid Disturbance enquiry committee : Healthiness of Batteries: All the constituents were requested to send the status of healthiness of Batteries to the SRPC Secretariat on monthly basis (i.e by 7 th of every month) Detailed Project Report (DPR) KPTCL informed that the implementation of 765 kv system in SR would increase the fault level which may require replacing the existing CBs with new high capacity CBs. KPTCL also informed the forum that in the DPR as sent by the many of the constituents did not include high capacity CBs. Minutes of the 24 th Protection Coordination Sub Committee Meeting held on Page 13

15 Hence KPTCL requested for revision in the DPR to include high capacity CB's due to configuration changes in the SR system. MS (I/c) suggested that this issue be discussed in the ensuing SRPC Meeting. 22. Remedial measures taken for the critical tripping events in the Southern Region. The constituents were requested to submit the remedial measures taken by them for the critical tripping events sent by SRPC secretariat by filing the remedial measure column of the word file at the earliest to SRPC secretariat. It was also requested that the complete tripping analysis report with (DR, EL) for the tripping incidents may please uploaded in the SRLDC website. 23. Sending Agenda items for the PCSC meetings. As per the Guidelines of CEA/MOP it had been decided to conduct the PCSC meetings on a monthly basis.it was requested that Agenda Items for the PCSC meetings, if any, may please be sent latest by 5 th working day of every month to SRPC Secretariat to compile and circulate the sameso as to have fruitful discussions in the PCSC meetings. 24. Agenda for the Sub Group meeting of PCSC. The following issues would be discussed in the Sub Group meeting the same was communicated vide SRPC Lr. Dated a) Power Swing Blocking Setting of Distance Relays b) Philosophy of Zone 3 Settings (POWERGRID to furnish details) c) Time delays in df/dt Relays d) Changes in over voltage setting if any, for 400 kv lines. (Changes in the present settings, if any, may please be sent to SRPC Secretariat latest by 11 th November 2013). 25. Date & Venue of the next Meeting The 26 th PCSC meeting would be conducted on (Thursday) preceded by the Sub Group meeting on Member Secretary i/c thanked all the Members &participants for their active contribution in the Meeting. ***** Minutes of the 24 th Protection Coordination Sub Committee Meeting held on Page 14

16

17

18

19

20

21 Tripping of Khammam ICT-1&2 at 11:45 hrs on 25 th September 2013 SRLDC observations: FIR reported that ICT s had tripped on operation of overload protection. It was reported that the triggering incident was a fault in 220kV KTPS-Manuguru line-1. All the 220kV lines at KTPS tripped from remote ends on Zone-2 protection. Figure 1 : SLD of 220kV Khammam switchyard

22 Figure 2 : Gooty 400kV bus voltage from PMU From Gooty PMU voltage it is observed that fault started at 11:45: hrs and cleared at 11:45: hrs i.e., in 560 milli seconds (approx). From D.R of ICT-2 the current in neutral starts from 11:45: hrs. From D.R of ICT-2 it is observed that the current was A in Secondary i.e Amps (CT Ratio = 1000/1A) and tripped in 450ms. In ICT-1 the maximum current observed was 1.8 A in secondary R and Y phase i.e. 1800A (CT ratio=1000/1a). Recommendation and further actions required: 1) It appears that the ICT s at Khammam have tripped before tripping of 220kV Khammam- KTPS line-1&2 which was not desired. 220kV Khammam-KTPS line-1&2 should have tripped in distance Zone-2 protection or on Directional earth fault (for high resistance fault) before tripping of the ICT s. The ICT protection needs to be coordinated with 220kV line protection at 400/220kV Khammam substation. 2) It is to be ensured that the ICT s have an IDMT characteristics for directional over current and earth fault and DMT characteristic s for high set of directional over current and earth fault. 3) The D.R of ICT-1 is not time synchronized with GPS and same needs to be rectified.

23 TRANSMISSION CORPORATION OF ANDHRA PRADESH LIMITED FAX MASSAGE DATED From The Chief Engineer/ Power Systems, APTRANSCO, Vidyut Soudha, Hyderabad. To 1) The Member Secretary, SRPC, 29, Race Course Road Bangalore ) The Executive Director, SRLDC, 29, Race Course Road Bangalore Lr.No.CPS/SP/111 /SRPC-FAX/Vol.3/D.No. 569/13, Dt: Sir, Sub: Grid breaker tripping at 11:46 Hrs on at KTPS - Reg. >>*<< INCIDENT: It is reported that at 11:46 Hrs on , a heavy fault occurred on 220 KV KTS-Manuguru I feeder and the conductors snapped at the following locations: 1. Yph conductor snapped between Tower locations 1 and Rph CVT jumper got cut. 3. Yph conductor got cut after the line isolator. 4. Bph jumper at the wave trap. 5. Rph jumper between line-in isolator and breaker. Due to the above incidents the following units and feeders got tripped: At KTS(O&M): The 220KV Nunna, Miryalaguda, Manuguru-1&2 and Lower sileru feeders from KTS(O&M) tripped on Zone-2 at remote ends. Also, the busbar protection operated, tripping all the 220 KV feeders and Units 2-8 at KTS(O&M) At KTS-V Stage: The 220KV Budidampadu-1&2, Seetharampatnam-1&2 and Lowersileru feeders from KTS-V stage tripped at other ends on Zone-2. Also, the units 9 and 10 are tripped at KTS-V

24 RESTORATION: By 12:15 Hrs the 220 KV KTS-V - Lower sileru and KTS-V Budidampadu 1&2 were taken in to service By 12:15 Hrs the 220 KV Shapurnagar, Lower sileru and Miryalaguda feeders from KTS(O&M) were taken into service. At 14:05 Hrs Unit-2 was synchronized at KTS(O&M) At 14:05 Hrs the 220 KV KTS-Manuguru II feeder was taken into service. At 14:18 Hrs the Unit-10 was synchronized at KTS-V. At 14:30 Hrs the Unit-4 was synchronized at KTS(O&M). At 14:37 Hrs, the Unit-8 was synchronized at KTS(O&M). At 14:53 Hrs, the Unit-9 was synchronized at KTS-V At 15:15 Hrs, the Unit-5 was synchronized at KTS(O&M). At 17:56 Hrs, the Unit-6 was synchronized at KTS(O&M). At 18:00 Hrs, the Unit-1 was synchronized at KTS(O&M). This is for the favour of information please. CHIEF ENGINEER POWER SYSTEMSt

25 Tripping of running units at Vijayawada TPS at 14:55 hrs on Running units-2,3,4,5&6 at Vijayawada TPS (connected at 220kV) tripped at 14:55 hrs on (Unit#1 was under shutdown). The generation loss was 900MW and change in frequency was 0.25 Hz

26 Analysis of the incident: From synchrophasor data of Ramagundam it can be observed that two faults had occurred, 1 st in B-Phase which was immediately followed by a fault in R-Phase. Both the faults were timely cleared. As per FIR of APTRANSCO the triggering incident was failure of triggering incident was B phase CT failure in 220kV VTPS-Narsaraopeta line at VTPS end. During discussion of the tripping in 25 th protection sub-committee meeting of SRPC on , it was informed by APTRANSCO representative that CT failure had also occurred in 220kV VTPS-Podili line at VTPS end. The 220kV Nasaraopeta line is connected to 220kV bus-2 and 220kV Podili line to 220kV Bus-1 at VTPS. Bus-bar protection of both the buses got acted due to failure of above CT s. D.R, E.L and final trip report not furnished by APTRANSCO/ APGENCO.

27 TRANSMISSION CORPORATION OF ANDHRA PRADESH LIMITED FAX MASSAGE DATED From The Chief Engineer/ Power Systems, APTRANSCO, Vidyut Soudha, Hyderabad. To 1) The Member Secretary, SRPC, 29, Race Course Road Bangalore ) The Executive Director, SRLDC, 29, Race Course Road Bangalore Lr.No.CPS/SP/111 /SRPC-FAX/Vol.26/D.No. 590/13, Dt: Sir, Sub: Grid breaker trippings on Reg. >>*<< Sl. No. Date Tripping Time (Hrs:mm) Element Type Element Remarks Normalisation Date Time (Hrs:mm) :56 220kV Line 220kV VTS- Narasaraopeta feeder The B-Phase CT on 220kV VTS- Narasaraopeta feeder got blasted at VTS end. The fault got cleared by the operation of Busbar protection, tripped all the 220kV feeders and units connected to Bus-1 & Bus-2. Failed CT to be replaced CHIEF ENGINEER POWER SYSTEMSt

28 ANNEXURE VI (1/4) Pending Tripping Details for Month of SEP-OCT 2013 ANNEXURE VI : File Avilable and Received Within 24 Hrs. : File Avilable and Received after 24 Hrs. (S): SENDER END TRIPPING DATE TRIPPING TIME 22-Oct-13 2:59 22-Oct-13 2:58 ELEMENT NAME kv VIJAYAWADA - VEMAGIRI kv RAMAGUNDAM HYDERABAD kv VEMAGIRI - GOUTHAMI CCCP 1 22-Oct-13 2: kv MYSORE - HASAN 2 21-Oct-13 23: kv NELLORE - ALAMATHI 400 kv TIRUNELVELI KUDAMKULAM 4 21-Oct-13 2:59 21-Oct-13 2: Kv KOLAR - SPDR 20-Oct-13 23: Oct-13 22:51 20-Oct-13 2: kv MYSORE - HASAN Kv GAJWEL - BHOOPALAPALLY kv WARANGAL - BOOPALPPALLI 2 20-Oct-13 2: kv MYSORE - HASAN 2 19-Oct-13 23: Kv GOOTY - NPS 2 19-Oct-13 16: kv SEDAM - TANDUR 17-Oct-13 13: kv HYDERABAD - N'SAGAR 17-Oct-13 12: kv KAIGA - GUTTUR 2 17-Oct-13 3: kv MYSORE - HASAN 2 17-Oct-13 3: kv MADURAI - PUGALUR 1 16-Oct-13 21: kv MADURAI - TIRUNELVELI 16-Oct-13 21: kv KANIAMPET - KADAKOLA 16-Oct-13 12: kv KAIGA - GUTTUR 2 16-Oct-13 11: kv AMBEWADI - PONDA 2 16-Oct-13 11: Kv KLVDPT - VALLUR 1 HVDC TALCHER - KOLAR POLE 1 AT TALCHER HVDC TALCHER - KOLAR POLE 1 AT TALCHER HVDC TALCHER - KOLAR POLE 2 AT TALCHER 13-Oct-13 19:03 13-Oct-13 1: Oct-13 0:42 12-Oct-13 23: kv MYSORE - HASAN 2 12-Oct-13 23: kv EDAMON - EDAPPON 11-Oct-13 12: Kv NCTPS - VALLUR 2 10-Oct-13 16: /220 kv ICT-1 AT CHITTOOR 9-Oct-13 13: /220 kv ICT-1 AT CUDDAPAH 9-Oct-13 12: /220 kv ICT-2 AT CHITTOOR 9-Oct-13 10: kv KURNOOL - SRISAILAM 8-Oct-13 15:53 25 File Not Avilable. (R): RECEIVER END SN 2 : kv SRISAILAM-MAMIDIPALLI 2 8-Oct-13 15: Kv TRICHUR - KOCHI 1 8-Oct-13 13: /220 kv ICT-2 AT CHITTOOR 8-Oct-13 12: kv KAIGA - GUTTUR 1 8-Oct-13 10: /220 kv ICT-1 AT N'SAGAR 7-Oct-13 23: kv KALPAKKA - VEMAGIRI 1 7-Oct-13 17: kv VTPS IV - SRISAILAM 2 7-Oct-13 17: kv VIJAYAWADA - VEMAGIRI 1 7-Oct-13 14: kv VIJAYAWADA - VEMAGIRI 1 7-Oct-13 14: kv KALPAKKA - VEMAGIRI 1 7-Oct-13 14: kv KAIGA - GUTTUR 1 7-Oct-13 12: /220 kv ICT-2 AT GOOTY 6-Oct-13 12:56 FIR (S) 1 DR (S) EL (S) FIR (R) DR (R) EL (R) DETAILS

29 Pending Tripping Details for Month of SEP-OCT 2013 ANNEXURE VI /220 kv ICT-2 AT CHITTOOR 6-Oct-13 12: kv KANIAMPET - KADAKOLA 6-Oct-13 11: kv TALAGUPPA - HASSAN 5-Oct-13 22:50 48 VIJAYAWADA TPS-UNIT 2 4-Oct-13 14:56 49 VIJAYAWADA TPS-UNIT 3 4-Oct-13 14:56 50 VIJAYAWADA TPS-UNIT 4 4-Oct-13 14:56 51 VIJAYAWADA TPS-UNIT 5 4-Oct-13 14:56 52 VIJAYAWADA TPS-UNIT 6 4-Oct-13 14: kv MAHABOOB NAGAR - RAICHUR 4-Oct-13 10: Kv GAJWEL - BHOOPALAPALLY 2 3-Oct-13 16: kv VEMAGIRI - GOUTHAMI CCCP 2 3-Oct-13 15: /230 Kv ICT-1 AT SUNGUVARCHATRAM 3-Oct-13 15: kv AMBEWADI - PONDA 2 3-Oct-13 12: kv VIJAYAWADA - VTPS IV 2 3-Oct-13 6:49 59 GOOTY-SOMANAHALLI AT GOOTY 3-Oct-13 3: kv NEYVELI TS 2- PONDICHERY 2-Oct-13 23: Kv PONDICHERY - SPCHATRAM 2-Oct-13 23: kv AMBEWADI - PONDA 2 2-Oct-13 14: kv GUMMUDIPUNDI - 63 SULLURPET 2-Oct-13 14:00 64 HVDC BHADRAVATHI POLE 1 1-Oct-13 16:28 65 HVDC BHADRAVATHI POLE 2 1-Oct-13 16: kv TIRUNELVELI - KUDAMKULAM 2 1-Oct-13 3: kv TIRUNELVELI - KUDAMKULAM 2 1-Oct-13 2: kv AMBEWADI - PONDA 1 29-Sep-13 21:47: kv KAIGA - KODASALLY 29-Sep-13 21:47: kv MYSORE - HASAN 2 29-Sep-13 17:59: kv KAIGA - GUTTUR 2 29-Sep-13 15:12: kv KHAMMAM - MAMIDIPALLY Sep-13 19:44: kv AMBEWADI - PONDA 1 28-Sep-13 15:23: kv KANIAMPET - KADAKOLA 28-Sep-13 12:08: kv IDUKKI - UDUMALPET 27-Sep-13 13:07: kv TIRUNELVELI - KUDAMKULAM 3 27-Sep-13 12:41: /220 kv ICT-1 AT KHAMMAM 25-Sep-13 11:45: /220 kv ICT-2 AT KHAMMAM 25-Sep-13 11:45: kv TALAGUPPA - HASSAN 24-Sep-13 22:17: /230 kv ICT-1 AT NEYVELI 24-Sep-13 14:06: kv KAIGA - GUTTUR 1 24-Sep-13 0:16: Kv HASSAN - UPCL 2 23-Sep-13 23:44: Kv GOOTY - NPS 1 22-Sep-13 3:02: kv RAMAGUNDAM - GAJWEL 20-Sep-13 17:09: kv SEDAM - TANDUR 20-Sep-13 7:23: kv VTPS IV - SRISAILAM 2 19-Sep-13 10:05: Kv VTPS - MALKARAM 2 19-Sep-13 9:54: kv TALAGUPPA - HASSAN 18-Sep-13 23:56: kv MYSORE - HASAN 1 18-Sep-13 23:29: kv KAIGA - NARENDRA 1 18-Sep-13 23:20: Kv HASSAN - UPCL 1 18-Sep-13 16:00: Kv HASSAN - UPCL 2 18-Sep-13 16:00: kv RAMAGUNDAM - N'SAGAR 1 18-Sep-13 3:23: kv MADURAI - PUGALUR 1 17-Sep-13 15:01:00 2

30 Pending Tripping Details for Month of SEP-OCT 2013 ANNEXURE VI Kv HIRIYUR-BTPS 1 17-Sep-13 4:33: kv TALAGUPPA - HASSAN 16-Sep-13 23:43: kv GOOTY - NELAMANGALA 16-Sep-13 23:16: /220 kv ICT-2 AT CUDDAPAH 16-Sep-13 4:14: /220 kv ICT-1 AT CUDDAPAH 16-Sep-13 4:14: kv GUTTUR - HIRIYUR 1 16-Sep-13 1:56: Kv GOOTY - NPS 1 16-Sep-13 0:01: kv MYSORE - HASAN 1 15-Sep-13 23:31: kv CHITTOR - THIRUVALEM 15-Sep-13 22:45: kv GUTTUR - NARENDRA 1 15-Sep-13 0:01: kv KAIGA - NARENDRA 1 15-Sep-13 0:01: kv MYSORE - HASAN 1 15-Sep-13 0:01:00 400/230 kv ICT 1 AT 107 PONDYCHERRY 13-Sep-13 12:52: kv HASSAN - NEELAMANGALA 1 13-Sep-13 3:02: kv KAIGA - GUTTUR 2 13-Sep-13 0:05: kv MYSORE - HASAN 1 12-Sep-13 23:10: Kv GOOTY - NPS 2 12-Sep-13 2:55: /220 kv ICT-1 AT HOODY 12-Sep-13 0:04: kv MYSORE - HASAN 1 12-Sep-13 0:01: kv MYSORE - HASAN 1 11-Sep-13 0:01: kv VIJAYAWADA - NELLORE 1 10-Sep-13 3:04: Kv KRISHNAPATNAM NELLORE 1 10-Sep-13 3:04: Kv NPS - NELLORE Sep-13 3:04: kv VIJAYAWADA - NELLORE 2 10-Sep-13 3:04: Kv GOOTY - NPS 2 10-Sep-13 3:04: kv KURNOOL - GOOTY 10-Sep-13 3:04: kv NELLORE - ALAMATHI 10-Sep-13 3:04: Kv NELLORE - SPDR 10-Sep-13 3:04: Kv NPS - NELLORE Sep-13 2:46: kv KAIGA - GUTTUR 1 10-Sep-13 0:23: kv HASSAN - NEELAMANGALA 1 9-Sep-13 23:59: kv MYSORE - HASAN 1 9-Sep-13 23:49: kv VIJAYAWADA - NELLORE 2 9-Sep-13 2:24: Kv KRISHNAPATNAM NELLORE 2 9-Sep-13 1:34: kv NELLORE - ALAMATHI 9-Sep-13 1:34: kv VIJAYAWADA - NELLORE 1 9-Sep-13 1:34: Kv NPS - NELLORE -2 9-Sep-13 1:34: Kv NELLORE - SPDR 9-Sep-13 1:33: Kv NPS - NELLORE -1 9-Sep-13 1:01: kv MYSORE - HASAN 1 8-Sep-13 22:57: kv MYSORE - HASAN 1 7-Sep-13 23:56: /220 kv ICT-2 AT N'SAGAR 7-Sep-13 17:16: kv RAMAGUNDAM - N'SAGAR 1 7-Sep-13 17:16: kv SEDAM - TANDUR 7-Sep-13 0:13: Kv NPS - NELLORE -1 6-Sep-13 4:03: kv PONDYCHERRY- VILLIANUR 5-Sep-13 18:51: Kv GOOTY - NPS 2 4-Sep-13 0:24: kv HASSAN - NEELAMANGALA 1 3-Sep-13 23:58: Kv KOLAR - SPDR 3-Sep-13 23:58: Kv NPS - NELLORE -1 3-Sep-13 23:55: kv MYSORE - HASAN 1 3-Sep-13 23:48: /220 kv ICT-1 AT HYDERABAD 3-Sep-13 18:15: kv KANIAMPET - KADAKOLA 3-Sep-13 12:57: kv AMBEWADI - PONDA 2 3-Sep-13 12:52: kv TALAGUPPA - HASSAN 1 2-Sep-13 22:42:00 3

31 Pending Tripping Details for Month of SEP-OCT 2013 ANNEXURE VI Kv HIRIYUR-BTPS 2 2-Sep-13 22:36: kv KAIGA - GUTTUR 2 2-Sep-13 11:41: /220 kv ICT-1 AT GUTTUR 2-Sep-13 11:41: /220 kv ICT-2 AT GUTTUR 2-Sep-13 11:41: kv UDUMALPET - TIRUNELVELI Sep-13 17:59: kv AMBEWADI - PONDA 2 1-Sep-13 3:05: Kv KRISHNAPATNAM NELLORE 1 1-Sep-13 2:13: Kv NELLORE - SPDR 1-Sep-13 2:01: Kv NPS - NELLORE -1 1-Sep-13 2:01: kv VIJAYAWADA - NELLORE 2 1-Sep-13 2:01:00 4