SOUTHERN REGIONAL POWER COMMITTEE BANGALORE

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2 SOUTHERN REGIONAL POWER COMMITTEE BANGALORE MINUTES OF THE 15 th MEETING OF PROTECTION SUB- SRPC HELD ON COMMITTEE OF 1. INTRODUCTION 1.1 The 15 th meeting of Protection Sub-Committee was held on 18 th July 2012 in the Conference Hall of Southern Regional Power Committee, Bangalore. The list of participants for the PCC meeting is enclosed as Annexure-I. 1.2 Shri S.R.Bhat, Member Secretary (I/c), SRPC welcomed the new members and participants to the 15 th meeting of the Protection Sub-Committee. He informed the forum about the deliberations of the Spl meeting of PCC held at Kaiga on and also the recommendations made during the Spl meeting of PCC held on to discuss the partial grid disturbance on He also informed the forum regarding the recommendations finalized during 1 st Monitoring Committee of the PCC which was held on MS (I/c) also informed the forum that a special meeting of PCC was scheduled to held in the afternoon session to discuss the 400 KV Vijayawada Nellore SPS Scheme. Member Secretary (I/c) requested Shri Satbir Singh, SE to take up the Agenda items for discussions. 1

3 2. CONFIRMATION OF THE MINUTES OF THE 14th PROTECTION SUB- COMMITTEE MEETING HELD ON 21st March The Minutes of the 14 th Protection Sub-Committee Meeting were since no comments were received from the constituents. confirmed 3. SYSTEM DISTURBANCES The System Disturbances / Occurrences in the Southern Region i.e. Grid Disturbances, Grid Incidents occurred during the period from February 2012 to May 2012 were discussed in the meeting. 4. Grid Disturbances 4.1) Grid Disturbance on 3 rd April 2012 in Karnataka System. (i) Time and date of event : 3 rd April 2012 at Hrs (ii) Location : North Karnataka (iii) Plant and/or Equipment directly involved : (iv) North coastal Karnataka and 400 kv Guttur SS, 400 kv Kaiga SS, 400 KV Narendra and Nagjheri, Kodasalli, Kadra, Kaiga, Narendra, Hubli, Bidnal, Guttur and Ambewadi S/S became dead. Description and cause of event At 11:01 Hrs, due to a suspected momentary DC grounding of the isolator NO/NC contact wires running from individual bay bus selection isolator to 400kv bus bar protection relay panel, Bus bar protection relay operated at 400kV Guttur. (v) Antecedent conditions of load and generation, including frequency, voltage and the flows in the affected area at the time of tripping including Weather Condition prior to the event 2

4 Prefault Scenario Haveri MLPur Vajramatti RTPS A.wadi Goa Narendra Soundattti Gadag Munirabad Alipur Kadra KSHally Hubli BTPS NPH Bidnal Harti Lingapur JSW Kaiga Sirsi Guttur SGS Hiriyur The status of 220 kv lines were as follows. a. Bidnal-Soundatti line was open at Bidnal. b. Haveri 1 & 2 lines were open at Narendra. c. Vajramatti- Mahalingapura 1 & 2 were open at Vajramatti. d. Kadra- Kodasahalli was under LC. e. Narendra-Ambewadi 1 & 2 were under LC. f. NPH (Nagjhari)-Ambewadi-1 was under LC. Generation at NPH MW Generation at Kaiga MW Generation at Kadra - 90 MW Generation at KShally MW Generation at Jindal MW Generation at BTPS MW Load on Bidnal Harthi 1 & 2-97 MW each Hubli-Sirsi 1 & 2-22 MW each Guttur bus was handling about MW 3

5 (vi) Demand / Generation interrupted Generation Loss MW and Load Loss 2000 MW (vii) Sequence of trippings with time. At 11:02 hrs: a. Guttur 400 kv bus became dead because of mal-operation of bus bar protection relay due to DC ground. b. The units at Kaiga went on to house load. 400 kv & 220 KV switch yard got de-energized. Hence Narendra 400 KV bus became dead. c. The load on Bidnal-Harti 1 & 2 lines increased to about 350 MW each from 97 MW and tripped on over load. d. This caused the increase in loading of Hubli-Sirsi 1 & 2 lines to 240 MW each from 154 MW and tripped on over load. e. This created an island of 220 KV systems including the generating stations Nagjhari, Kadra & KS Hally and the substations Hubli, Bidnal, Narendra etc. f. The frequency in this islanded area increased and the units at Nagjhari, Kodasahalli & Kadra tripped on over speed and the bus became dead at the above stations. g. 400 KV RTPS-BTPS tripped on over voltage at BTPS and BTPS- Jindal tripped at Jindal. 220 kv BTPS-Lingapur tripped on over load. h. The lone 220 kv BTPS-Alipura line carrying 73 MW and the unit ramp down to 73 MW survived at BTPS. At BTPS, when Lingapur line was charged, all the lines and unit tripped immediately. (viii) Remedial measures/restoration a. Supply was resumed to Nagjhari from Sirsi via Harthi and subsequently units and lines were charged at 11:40 Hrs. b. Supply was resumed to Kaiga from Hiriyur via Guttur and subsequently units and lines were charged at 11:47 Hrs. 4

6 c. Start up power for BTPS was extended from JSWEL. DELIBERATIONMS IN THE PCC: It was informed to the forum that this incident was discussed in detail during the special meeting of PCC held on in SRPC Secretariat, Bangalore. The recommendations of the Spl meeting PCC forum would be discussed in detail in item No ) Grid Disturbance on 18 th April 2012 at NLC. (i) Time and date of event : 18 th April 2012 at Hrs (ii) Location : Neyveli,Tamilnadu (iii) Plant and/or Equipment directly involved : Neyveli TPS KV Sub station (iv) Description and cause of event At 09:23:39 Hrs, due to internal fault in the B-phase SF6 CT of 400 KV Neyveli-TPS- Puducherry line, SF6 pressure had come down to zero and feeder got tripped. During the auto reclosing at 09:23:40 Hrs both the 400 KV buses got cleared on Bus bar protection. Neyveli TPS 2 Stage II Units 4, 5, 6 & 7 went on house load and 400 KV Neyveli TPS 2 buses (Double Main one Transfer Bus scheme) became dead. (v) Demand / Generation interrupted Generation Loss- 850 MW 5

7 (vi) Details of Relay Operation : 86 C, 86 T, 86 TX, 85 LO Num Relay- B Ph Zone-1 operated Auto reclose operated carrier send SF6 CT alarm relay (Both stage-1 & stage-2) (vii) Restoration: 1. Immediately after the incident, Restoration process started and 400/230 KV ICT 2 was closed at 09:44 hrs & 400 KV Neyveli TPS 2 Salem 1 line was closed at 09:57 Hrs to enable the restoration of house load units to the bar. 2. At 10:08 Hrs, 400/230 kv ICT 1 was closed. 3. At 10:09 Hrs, 400kV Neyveli TPS 2 Trichy line was closed. Subsequently, Neyveli TPS 2 Stage II Unit 5 & Unit 6 normalized from house load at 10:12 Hrs & 10:14 Hrs respectively. 4. At 10:21 Hrs, 400kV Neyveli TPS 2 Salem 2 line was closed. 5. At 10:43 Hrs, 400kV Neyveli TPS 2 Neyveli TPS 1 (Exp) line was closed. Subsequently, Neyveli TPS 2 Stage II Unit 7 normalized from house load at 10:47 Hrs. 6. At 10:48 Hrs, 400kV Neyveli TPS 2 Pugalur line was closed. 7. Neyveli TPS 2 Stage II Unit 4 could not able to normalized from house load & later taken out on water wall tube leakage. DELIBERATIONS IN THE MEETING CM, NLC informed the forum that NLC had purchased a new CT from M/s Siemens and they sought the manufacturer s detailed report regarding the above incident. PCC RECOMMENDATIONS The forum recommended NLC to send a detailed analysis report of the incident to the PCC forum. 6

8 4.3) Grid Disturbance on 27 th April 2012 in the Karnataka System. (i) Time and date of event : 27 th April 2012 at Hrs (ii) Location : Guttur, Karnataka (iii) Plant and/or Equipment directly involved : (iv) 400 KV Guttur Substation Description and cause of event A Bus fault occurred at 400kV Guttur SS due to flashover of B-phase Lightening Arrester of 400kV Guttur-Hiriyur-Line 2. Bus bar protection operated and all 400 KV feeders got tripped along with 400/220 KV ICTs. (v) Antecedent conditions of load and generation, including frequency, voltage and the flows in the affected area at the time of tripping including Weather Condition prior to the event Prefault Scenario: 383MW 2 X 229MW Hiriyur PGCIL JSW Munirabad 70MW 2 X 13MW R-Ph LA flashed 178MW 2200kV bus Narendra 2 X 315 MVA 2 X 79MW Kaiga 400 kv Bus Guttur Total Load 636 MW 7

9 (vi) Demand / Generation interrupted Generation Loss- 415 MW (vii) Sequence of trippings with time. a. At 17:44:55 Hrs on 27 th April 2012, the R-phase LA of 400 kv Hiriyur line-ii flashed over at 400 kv station Guttur. b. The line immediately tripped (Single pole tripped) on distance relay, R-N, (MiCOM-P442), zone-1, and fault current R-N 12 ka. Single pole A/R operated and again tripped (Three pole tripped) on distance relay, SOTF, R- N, (MiCOM-P442), zone-1, fault current R-N 11KA. c. Before tripping of line on distance relay after auto reclosing, the bus bar protection relay mal-operated and tripped all 400 KV lines and ICTs causing 400 kv bus shutdown at Guttur. (viii) Restoration: Hrs MVA ICT-II charged Hrs kV Beeranahalli-I (Hiriyur) charged Hrs kV Narendra-I charged Hrs kV Kaiga-I charged Hrs kV JSWEL charged Hrs MVA ICT-I charged Hrs kV Munirabad charged Hrs kV Narendra-II charged Hrs kV Kaiga-II charged. DELIBERATIONS IN THE MEETING KPTCL informed that the bus bar differential relay was tested after the occurrence and found to be in order. However, the upgradation of the existing bus bar protection is also proposed. The flashed over LA of 400 kv Hiriyur line-ii was replaced on and the line was charged at 22:00 Hrs on

10 PCC RECOMMENDATIONS The PCC forum recommended KPTCL to forward the detailed report from KPCL regarding tripping of BTPS units. 4.4) Grid Disturbance on 25 th June 2012 in Karnataka System. On at 03:24 Hrs 220kV Lingapur SS got tripped. The forum requested KPTCL to send the detailed analysis of the incident with the details as mentioned in the IEGC (c) The forum also requested KPTCL/SLDC to demand for the detailed report from BTPS and the same may be forwarded to the SRPC, Secretariat at the earliest. The forum opined that the Grid disturbance would be discussed in the next PCC. PCC RECOMMENDATIONS The PCC forum recommended that Bus bar protection at Lingapura S/S may be implemented within 6 months time to avoid the grid disturbance similar to ) Grid Disturbance on 30 th June 2012 Date and Time: Reported Disturbance/Fault: 30-Jun-2012 & 12:59:12 Hrs CT Blast on 400kV Gazuwaka-Kalpakka-1 at Gazuwaka end. The forum requested PGCIL, SRTS II to send the detailed analysis of the incident with the details as mentioned in the IEGC (c) The forum opined that the Grid disturbance would be discussed in the next PCC. 9

11 5. Talcher Kolar HVDC Poles Trippings: 5.1 Tripping of Pole I and Pole II on at 14:32 Hrs due to Commutation failure a.the incident report as submitted by SRTS II, PGCIL is as follows. 10

12 b. The Grid incident report as submitted by SRTS II,PGCIL as follows. SRTS-II,PGCIL REPORT ON BIPOLE TRIP ON (i) Pre fault Condition On both Poles were in service with Bipolar power of 2000 MW on AC side of Talcher. At Kolar, Pole 1 & Pole 2 power was 915 MW each. Bus frequency was 49.7 Hz. (ii) During fault: At 14:32 hrs, Pole1 & Pole 2 have tripped due to ESOF from other side. At Talcher it was observed that Pole control has generated ESOF for both Poles. The Pole current was limited due to Low Short Circuit Ratio on HVDC. Both Poles have tripped almost simultaneously with a delay of 65msec. Both Poles have remained in Block condition at Kolar & under standby at Talcher. AC Filter bank 1 has tripped on Over voltage stage -1 (delay of 1 sec). On initial analysis of SER, it was observed that there were several commutation failures in both Poles. AC frequency has dropped to 48.8Hz. (iii) Analysis for Operation of HVDC: On detailed analysis of the events and the TFR recordings, it is observed that there were repeated commutation failures on both Poles at Kolar. Pole 1 & Pole 2 has experienced 7 commutation failures each. As per design of HVDC controls, the protection inherent to Pole control detects reduced short circuit level by repeated commutation failures. If a commutation failure is detected for the affected pole, a monitoring time (1 min.) is started and a counter is incremented. If the counter reaches a first limit (3) during this time period, the respective pole current limit is decreased to 75% (Stage 1). As soon as a second limit (6) of commutation failures is reached within the monitoring period, a further decrease to 50% is initiated (Stage 2). If after a delay (Pole 1: 200 ms, Pole 2: 400 ms) again a commutation failure is detected, the pole is finally tripped (Stage 3).Extinction angle (Gamma) values lower than a certain limit (3 ) in the affected pole is the indication criteria for commutation failure detection. It is observed that 11

13 the 400kV Bus voltages at Kolar have reduced to as low as 266kV, 285.7kV & kV in R,Y &B phases respectively. These are the minimum voltages seen from TFR at Kolar bus. The disturbance has lasted for 1.2sec as seen from the AC voltage dip. Since the AC side fault was not cleared in time, after 7 th commutation failure, both Poles have tripped on reduced short circuit level protection as explained above. (iv) Actions Taken: It was confirmed by CPCC that there was a CT failure in one of the KPTCL stations at Somanahalli. Since the fault was external to HVDC and clearance was given SRLDC, Pole 2 was deblocked at 15:02 hrs in GRM. After increasing the power flow to 150 MW Pole 1 was deblocked at 15:08 hrs. Both poles were in service in bipolar mode at 15:08 hrs and power flow was increased as per the SRLDC requirement. (v) Extension of Inter trip signal / SPS: SPS signals were not generated. During commutation failures on both Poles, power flow reduces to zero and increases to nominal value after recovery of the AC system. However, in this case, there were repeated commutation failures in both poles and by the time Poles were blocked the actual power loss was not captured by the PLC logic and SPS was not generated. It is expected that the modification proposed by POWERGRID & submitted for approval to SRPC may help in resolving such issues. Relevant SER printouts were submitted to SRPC. (viii) Analysis: AT Somanahalli SS of KPTCL One no of 220 kv CT in R phase of HSR layout feeder blasted at 14:31Hrs. During blasting of the CT, the jumper of R phase has short circuited with Y phase. From the fault records it can be seen that the fault was sensed at ms. As the primary bus bar protection of KPTCL provided on the 230 kv side bus bar has not operated, the fault continued up to 14:32: hrs and both transformers were subjected to a fault current of 4kA separately. The Back up over current protection (IDMT) provided on the HV side of ICTs operated and isolated the fault. 12

14 DELIBERATIONS IN THE MEETING It was brought to the notice of the forum that the incident was discussed in the special meeting of PCC held at Somanahalli on and recommendations were made to avoid similar occurrences. The Spl PCC recommendations would be discussed in detail item No 35. SE, KPTCL informed that the R&M works of Somanahalli S/S was awarded to M/s Easun Reyrolle. KPTCL informed that it is in the process of strengthening of Somanahalli corridor so as to enable 220 KV lines to operate in grid mode for the purpose of increased reliability. It was also informed that KPTCL would be implementing a SPS to ensure continued power supply to water pumping stations at TK Halli and Harohalli. 5.2 Tripping of Pole I tripped and Pole-2 came on Ground Return mode on at 17:48Hrs Due to HVDC line fault at Location no 56, km from Talcher end. a. The incident report as submitted by SRTS II, PGCIL is given below. 13

15 5.3 Tripping of Talcher-Kolar Pole-2 and Pole-1 came on Ground Return mode on at 16:14Hrs Due to HVDC line fault at Location no 57, km from Talcher end. a. The incident report as submitted by SRTS II, PGCIL is given below 14

16 6. Minor Trippings The Minor tripping in the Southern Region are given in Annexure II as submitted by Lr No SRLDC/SRC&S/Prot/2012 /4559 dt Requirement of SPS for 400 KV Nellore-Almatti DC line contingency. SRLDC Vide Lr No Lr No SRLDC/SRC&S/Prot/2012 /4559 dt (item No 5) had proposed for a System Protection Scheme for 400 KV Nellore-Almatti DC Line contingency. With the commissioning of Simhapuri (300 MW) and Meenakshi (300 MW) units 400 KV Nellore-Almatti DC line may get severely loaded. The strengthening of this corridor would be achieved with the Commissioning of the Nellore-Tiruvalum line which is expected by the year SRLDC was therefore 15

17 proposing an SPS to back down generation at Simhapuri & Meenakshi to alleviate the post contingency flows on N-1 condition of this line. DELIBERATIONS IN THE MEETING The PCC forum agreed for the SPS in principle and the matter would be taken to the higher forum for approval. PCC RECOMMENDATIONS The forum recommended SRLDC to fine tune the SPS scheme to proceed with the 400 KV Nellore Almatti DC Line contingency SPS. 8. SPS for 220kV Chittoor- Tiruvalum and 220kV Sullurpet- Gummidipoondi lines. SRLDC Vide Lr No Lr No SRLDC/SRC&S/Prot/2012 /4559 dt (item No 15) had proposed for a System Protection Scheme for 220kV Chittur- Tiruvalum and 220 KV Sullurpet-Gummidipoondi lines. Presently, 220 KV Chittoor-Tiruvalum line O/C setting at Chittur end is 420 A (160 MW) and 220 KV Sullurpet-Gummidipoondi line O/C setting at Sullurpet end is 260 A (100 MW). The constraint is due to the loading concern on the upstream lines. Considering this fact it was felt prudent to design an SPS to trip 220 KV Chittoor- Tiruvalum and 220 KV Sullurpet-Gummidipoondi lines based on the loading of the critical upstream lines instead of over current protection and Line will be protected by distance protection. DELIBERATIONS IN THE MEETING APTRANSCO informed the forum that the Over current settings of 220 KV Chittoor Tiruvalum Line at Chittoor end was set to 600 A. 16

18 For the 220 KV Sullurpet Gummidipoondi Line The PCC forum agreed for the SPS in principle and the matter would be taken to the higher forum for approval. PCC RECOMMENDATIONS The forum recommended SRLDC to fine tune the SPS scheme for both the lines KV Hiriyur-Nelamangala D/C Contingency SPS Proposal for a SPS in 400 KV Hiriyur Nelamangala Line was discussed in the PCC and OCC meetings. In view of proposed commissioning of Bellary TPS Unit-II a SPS during tripping of one circuit of 400 kv Hiriyur-Nelamangala line when flow of each line was more than 560 MW was deliberated in the meetings. It was informed that 400kV Hiriyur-Nelamangala SPS was implemented partially (tripping of Jindal units were wired, BTPS final link for tripping yet to be extended). It was noted in the 72 nd meeting of OCC that the SPS scheme was under active implementation by KPTCL. It was informed that the remaining pending works would be completed in about one month s time. DELIBERATIONS IN THE MEETING SE, KPTCL informed that the SPS is approved by KPTCL management. The scheme is to trip 1 unit of 300 MW at JSW when the load on the remaining Hiriyur-Nelamangala line crosses 800MW and remains in between MW when the other line trips. If the load crosses 1000 MW, 1 unit of 500 MW at BTPS will be tripped. It was also informed that the PLC logic controller has been procured and installed at Nelamangala and logic has been configured. The SPS logic is enclosed for information (as Annexure III). 17

19 A trip signal would be generated at Nelamangala by PLC logic and the same would be transferred either to JSW or to BTPS (KPCL) depending on the condition. It was informed that M/s JSW has developed an internal logic to trip one unit if a signal is received from Nelamangala and the generation at JSW is more than 700 MW. The logic is also enclosed (Annex-IV). It was informed that M/s KPCL has given their consent to trip one unit of 500 MW. KPTCL has to procure PLC logic controller license and the work is under progress. PCC RECOMMENDATIONS The forum recommended KPTCL to implement the SPS at the earliest. 10. SPS at Hosur S/S SRTS II,PGCIL vide Lr No SR II/O&M/ /F-42.0 dt informed that the controlled load shedding of 315 MVA ICTs at 400/220 KV Hosur S/s to mitigate the overloading of one ICT in case of tripping of other has been implemented w.e.f PCC RECOMMENDATIONS The forum recommended SRTS II, PGCIL to inform the operation/non operation and unintended operation if any of the SPS for information and perusal of the PCC forum. 11. Status of provision of SPS Trip Signal 3 at Kolar The proposal for Generation of third protection signal from Kolar in view of higher power transfer (2000 to 2500 MW) was approved in 13 th SRPC meeting. In 14 th PCC meeting SRTSII, PGCIL informed that inter trip signal-3 would be ready by May

20 The Extended mode of operation of Talcher-Kolar HVDC link and its duration would continue throughout the year as decided in SRPC meeting held on 1 st June 2012 depending upon the ambient temperature. The Trip Signal 3 to cover loss of 2500 MW is required to be in place at the earliest and it would also be ensured that the other 2 Trip signals are generated and acted upon. DELIBERATIONS IN THE MEETING SRTS II, PGCIL informed the forum that the space to provide the equipments would be taken up and the trip signal 3 would be ready by August PCC RECOMMENDATIONS The PCC forum recommended PGCIL to implement the SPS Trip Signal 3 within the agreed time. 12. Modification of SPS Trip Signal at Kolar SRTS II, PGCIL vide dt had informed that the modifications as suggested in the special meeting of PCC have been implemented on PGCIL also informed that the revised logics were uploaded in the PLC and tested locally and found to be working. The revised logic is as follows Trip generation LOGIC Condition 1: ((500MW<Power loss :S1000MW) & Pole Block) OR (l400mw< Power flow :S1900MW) & Pole Block) OR (under one pole s/d (500MW<Power flow <1000MW)) other Pole Blocks= TRIP I Condition 2: (650MW<Power flow :S1150MW) & Line fault & Pole Block = TRIP I Condition 3: ((Power loss >1000MW) & Pole Block OR (Power flow >1900MW) & Pole Block) OR (under one pole s/d (Power flow> 1000MW)) other Pole Blocks = TRIP II Condition 4: (Power flow> 1150MW) & Line fault & Pole Block = TRIP II *Power loss = DC power at Kolar at (t-2sec) - DC power at Kolar at (t) where t is the time instant when Block signal is available. Power flow = DC power at Kolar at (t-2sec). This is for the information and perusal of the PCC forum. 19

21 13. SPS for Kudankulam DELIBERATIONS IN THE MEETING SRTS II, PGCIL informed the forum that the SPS would be ready by end of July PCC RECOMMENDATIONS The PCC forum recommended PGCIL to implement the SPS for Kudankulam within the agreed time. 14. SPS at Varahi The PCC forum envisaged a SPS at Varahi in the earlier PCC meetings. 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. It was informed that 220 kv Varahi Shimoga D/C line severely loaded with no N-1 reliability. DELIBERATIONS IN THE MEETING SE, KPTCL informed that as 400 kv line between UPCL Shantigrama (Hassan) is expected to be commissioned within 20 days, SPS at Varahi may be not required. Member Secretary (I/c) informed that as per the 14 th PCC recommendations the Scheme will be reviewed when Nandikur - Shantigrama 400 KV (Quad moose Conductor) line commissioned by KPTCL. The PCC forum requested KPTCL to proceed with the Varahi SPS. KPTCL informed that, the scheme algorithm, hardware, PLC license are ready. It can be implemented after getting KPCL s clearance. KPTCL agreed to implement the scheme on or before 15 th August PCC RECOMMENDATIONS The PCC forum recommended KPTCL to implement the SPS within the agreed time. 20

22 15. SPS for S1-S2 bid area: The PCC forum had suggested for 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. DELIBERATIONS IN THE MEETING CE, TANTRANSCO informed that the issue needed to be discussed in the OCC meeting. MS (i/c),srpc informed that the issue was discussed in the 70 th- 72 nd OCC and the OCC forum also requested TANTRANSCO to implement the SPS at the earliest. TANTRANSCO informed that the issue would be taken up with the management and by the end of August 2012 the SPS would be implemented. PCC RECOMMENDATIONS The PCC forum recommended TANTRANSCO to implement the SPS within the agreed time 16. SPS at Muddanur: The PCC forum proposed a SPS at Muddanur in the earlier PCC meetings. The 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 Pulivendala (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. 21

23 DELIBERATIONS IN THE MEETING APTRANSCO informed the forum that the SPS at Muddanur had been implemented and a letter in this regard would be sent to the SRPC secretariat at the earliest. PCC RECOMMENDATIONS The PCC forum congratulated APTRANSCO for commissioning the SPS at Muddanur and requested APTRANSCO to send the details of the SPS and the date and time of implementation of the SPS for the records and perusal of the PCC forum. 17. SPS on 400 kv Vijayawada-Nellore line The PCC forum 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 issue was discussed in various SRPC forum meetings and SRLDC had also provided additional study results. DELIBERATIONS IN THE MEETING It was informed that the issue had been discussed in the 19 th SRPC meeting held on 1 st June The issue would be further discussed in detail in the Special meeting of PCC convened on the Afternoon session of the PCC meeting. SPL PCC RECOMMENDATIONS The record of discussion in the Special meeting of PCC is enclosed as Annexure V 22

24 18. Operation and review of various SPS Scheme in the Southern Region In the 14 th PCC meeting the forum decided that the operation of Various SPS schemes in the Southern Region would be brought to the notice of the forum during the fourth coming PCC meeting. The forum proposed that the operation, non operation and mal operation of the SPS schemes would be discussed in the forth coming PCC meeting. S.NO SPS Description Operation Non Operation Mal Operation 1 SPS at Nagjhari Nil Nil Nil 2 SPS at Peenya Nil Nil Nil 3 SPS at HVDC Kolar 4 SPS at Hosur -* -* -* 5 SPS at -* -* -* Mamidipally Remarks Discussed in detail in item No 5 * data not received All the constituents are requested to send the particulars of operation, non operation and mal operation of SPS in the their system as per the IEGC reporting procedure.(i.e within 24 Hours ). DELIBERATIONS IN THE MEETING It was brought to the notice of the forum that in the sub group meeting of PCC held on 30 th April at Kaiga it was proposed to review the existing SPS at Nagjheri to take care of line loadings on Bidnal-Harthi and Hubli-Sirsi lines (action KPTCL). SE, KPTCL informed that the SPS would be modified latest by 15 th August

25 19. Uniformity in Protection Philosophy and Protection relay coordination in SR (i) TANTANSCO vide Lr No CE/P&C/SE/D/EPC2/AEE3/f SRPC/Dt given the following agenda. (ii) KSEB vide Lr No.CESO/EELD1/AE2GS/ PC/ dt nil sent the following agenda In the 12th meeting of the Special Protection committee, it was decided to adopt a zone II timing of 350 msec for having a uniform protection philosophy in the Southern region. Based on that, the Zone II timing for majority of 220kV feeders in our region have been changed to 350msec. But it was noticed that the setting of the feeders at Power grid end was non-uniform and because of this grading is not achieved. The current settings of the PGCIL feeders are listed below. Name of feeder current Zone#2 setting at PGCIL end kV PGCIL #1 at PothencodeS/s 450msec kV PGCIL #2 at PothencodeS/s 450msec 3. Edamon- Thirunelveli#1 at EdamonS/s 300msec 4. Edamon- Thirunelveli#2 at Edamon S/s 300msec 5. Kundara- Kayamkulam at Kayamkulam GIS S/s 500msec 6. Edappon- Kayamkulam at Kayamkulam GIS 500msec 24

26 DELIBERATIONS IN THE MEETING In the meeting CE,TANTRANSCO briefed the forum regarding the protection settings adopted in the 400 KV Substations of the TANTRANSCO substations.he also insisted for uniformity in the protection settings adopted by all the constituents of the Southern Region. SRTSII,PGCIL informed the forum that they would discuss the issues with KSEB & resolve it amicably. PCC RECOMMENDATIONS It was brought to the notice of the forum that the issue of uniformity and protection relay coordination issue of the SR constituents were discussed in detail in the Spl meeting of PCC held on SE, SRPC requested the constituents to adhere to the recommendations of the Spl PCC in respect of Protection relay coordination and uniformity in protection settings. 20. Provision of Single Phase Auto-Reclosing, Carrier Aided tripping and Bus Bar Protection Scheme on 220 KV and above lines in SR. In the earlier PCC meetings, it was agreed 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. The PCC forum recommended that all the constituents to have carrier aided tripping for all the 220 KV and above rated lines. The forum also recommended that all the constituents to have an independent Bus Bar protection scheme to protect their transmission system elements. 25

27 As on date the status of data submitted by the constituents is as follows. S.No Constituent 1 APTRANSCO Carrier Aided Tripping Status Data Submitted Single Phase Auto reclosing status Data Submitted Bus Bar Protection status Data Not* Submitted 2 KSEB Data Submitted Data submitted Data Submitted 3 KPTCL Data Submitted Data submitted Data Not * Submitted 4 TANTRANSCO Data Submitted Data submitted Data submitted 5 SRTS I,PGCIL Data Not submitted Data Not submitted Data Not * submitted 6 SRTS II,PGCIL Data Submitted Data submitted Data Submitted 6 NTPC Data submitted Data submitted Data Not * submitted 7 NLC Data Submitted Data Submitted Data Submitted 8 MAPS,NPCIL Data Not ^ submitted Data Not ^ submitted Data Not * submitted 9 KAIGA,NPCIL Data Not ^ submitted Data Not ^ submitted Data Not * submitted 10 Puducherry Data Submitted Data submitted Data submitted * Requested to send the updated List of Substations provided with Bus Bar Protection in as per the Annexure VI. ^ Requested to send the updated List of Lines provided with Carrier Aided Tripping /Single Phase Auto Reclosing scheme as per the Annexure VII. DELIBERATIONS IN THE MEETING CE, KPTCL informed the following in the meeting. 26

28 Status of Carrier aided Protection of 220 kv lines of KPTCL: Total Carrier protection Carrier protection to be provided provided Lines connected between KPTCL stations and Generating stations Lines connected between KPTCL stations and PGCIL stations Interstate lines Lines between Generating stations Lines between KPTCL stations Total It was informed that order was placed for protection couplers and the material will be expected by the end of Dec The proposed to be completed within 3 months. Status of Bus bar protection for KPTCL Substations: Total number of stations Number of station to which bus bar protection Number of station to which bus bar protection to be provided provided Out of 25 stations, about 5-6 stations are included in R & M works, Action would be initiated for other stations. 27

29 PCC RECOMMENDATIONS The PCC forum requested that all the constituents to send the updated status of implementation of provision of Carrier Aided Protection facility, Single Phase Auto reclose facility and provision of Bus Bar Protection facility in the 220 KV and above network in Electronic format (as per Annexure VI &VII) latest by to the following IDs Agenda from SRTS II,PGCIL (i) Commissioning of carrier aided protection scheme for all 220 kv lines (ii) Overloading of ICTs at Thirunelveli & Madurai- Requirement of SPS scheme: The Thirunelveli & Madurai ICTs are operating at near to full load and operating at overloads intermittently. The requirement of SPS may please be discussed in the meeting. (iii) Submission of tripping reports to SRLDC/SRPC by all utilities. DELIBERATIONS IN THE MEETING The forum requested all the constituents to provide carrier aided protection scheme to all 220 KV and above lines. The Protection Subcommittee agreed in principle for the SPS Scheme The forum also requested all the constituents to send the tripping reports with the details as mentioned as per IEGC (c) to SRPC Secretariat through to the following IDs

30 22. Islanding scheme for Jindal, BTPS. An islanding scheme covering Munirabad, Kustagi Sindhanur Loads and JSW Generators was proposed in the earlier PCC meetings. It was brought to notice of the forum that 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. M/s. KPTCL / KPCL was also requested to formulate an island for BTPS with radial loads at Munirabad, Kustagi and Sindhanur. The following Loads were identified by KPTCL for the proposed islanding scheme. Kustagi :107 MW, Sindhanur:55 MW, Munirabad:49 MW,Alipur:80 MW,Total:291 MW. DELIBERATIONS IN THE MEETING SE,KPTCL informed that the island would be formulated action had been initiated in this regard. 23. Islanding Scheme for Kaiga The provision of Islanding scheme for Kaiga Generators was discussed in the earlier PCC meetings. Kaiga, NPCIL was requested to formulate the Kaiga islanding scheme with adjoining loads in consultation with SRLDC, KPTCL &PGCIL. Islanding scheme for Kaiga had been discussed in detail in the 1 st meeting of Monitoring Committee held on and it was proposed to have two islands called Island12 and Island34. Details of scheme are discussed in item No

31 DELIBERATIONS IN THE MEETING Kaiga, NPCIL informed that the islanding scheme work would be examined for implementation after resolution of certain issue. PCC RECOMMENDATIONS The forum requested Kaiga, NPCIL in coordination with KPCL and KPTCL to formulate the islanding scheme at the earliest. 24. Islanding Scheme for Simadhri and VTS In the 15 th PCC meeting DE, APTRANSCO had proposed for an islanding scheme for Simadhri and VTS Generating unit with adjoining loads of APTRANSCO. DELIBERATIONS IN THE MEETING The forum requested APTRANSCO to formulate the Islanding scheme in consultation with NTPC and APGENCO. NTPC informed the forum that the scheme would be taken up with the management after formulation of the islanding scheme. 25. Non Submission of complete tripping Report by the constituents. SRLDC vide Lr No SRLDC/SRC&S/Prot/2012 /4559 dt (item no 13) had informed that though the constituents have started giving tripping reports for the trippings in their system most of the constituents are not submitting the DR/EL printouts. 30

32 DELIBERATIONS IN THE MEETING The issue was discussed in item No s 4.4, 4.5 and 21 and the constituents were requested to send the complete tripping/disturbance/incidence report to the SRPC secretariat at the earliest. 26. Review of Installation of Frequency Trend Relays (df/dt) and revision of df/dt settings in SR In the 14 th PCC the forum proposed a new df/dt settings for the SR system. Present df/dt Settings in SR: ALARM: Frequency <= 49.5 Hz and 0.3 Hz/sec fall of frequency (df/dt) Trip: Frequency <=49.3 Hz and 0.3 Hz/sec fall of frequency (df/dt) Then Load relief expected: 3530 MW in Peak condition 2909 MW in off Peak condition Proposed df/dt Settings in SR in addition to the existing setting: ALARM: Frequency <= 49.8 Hz and 0.2 Hz/sec fall of frequency (df/dt) Trip: Frequency <=49.5 Hz and 0.2 Hz/sec fall of frequency (df/dt) Then Load relief expected: 2000 MW in Peak condition. Status of df/dt Relays installed in Southern Region: S.NO Constituent System df/dt relay Setting Expected load relief (MW) 1 APTRANSCO 49.3 Hz, 0.3 Hz / Sec, 1767 Instantaneous 2 KPTCL -do- ( ) 3 TANTRANSCO -do KSEB -do- ( ) Total load relief in SR ( ) The issue was also discussed in the 70 th 72 nd were briefed about the revision in the df/dt settings. OCC and the constituents 31

33 DELIBERATIONS IN THE MEETING The constituents were requested to provide the additional relief at the earliest and the progress made in this regard may be intimated to the forum. 27. The issue of sending completed Dynamic Study data In the earlier meetings of PCC the forum decided to collect the Dynamic study data from the utilities to study the Southern Region system. The dynamic study format was circulated to the constituents to send the Generator, Excitation system, Governor, HVDC parameters.tneb, NLC, NTPC, Kayankulam and KSEB had submitted the filled format. The following constituents they have not sent the Dynamic study data as circulated in the minutes of the meeting. NTPC (Ramagundam), KPCL, APGENCO, MAPS & KGS (NPCIL). The forum opined that the dynamic study details of the IPPs also would be necessary to conduct the study on whole SR system. The forum insisted that the constituents who had not sent the data to send at the earliest. PCC RECOMMENDATIONS NTPC (Ramagundam), KPCL,,MAPS&KGS (NPCIL) were requested to send the dynamic study data (Annexure VIII) latest by All the SLDCs were requested to direct the embedded IPPs connected at 220 KV and above voltage level to send the completed dynamic study format (Annexure VIII) to the SRPC, Secretariat. It is requested that the dynamic study data in the stipulated format may be sent to us latest by by to the following IDs

34 28. Pilot PMU Project in the Southern Region. The pilot PMU project was approved in the 14 th SRPC meeting held at Kochi on 27 th August SRLDC proposed for 6 numbers of Phasor Measurement Units for the Southern Region at an estimated expenditure of Rs.4.0 Crores. DELIBERATIONS IN THE MEETING CM, SRLDC informed that PMU at Somanahalli had been commissioned on 17/07/2012 and the PMU started generating the data. It was noted that the other PMUs would be installed within 2 months time. 29. Expected UFRs load relief quantum: The Quantum of additional load relief to be provided by the constituents for the year as calculated by SRPC is given below. (Figures in MW) Constituents? AP KAR KER TN PUDU SR Stage - 25% Hz Stage % Hz Stage - 40% Hz Total (implemented) ? Additional Requirement?

35 DELIBERATIONS IN THE MEETING In the meeting the constituents were requested to send the UFR trippings to SRPC at the earliest. The forum also requested to provide the designated relief at the earliest. The status of provision of designated relief may be intimated to the PCC forum. 30. Emergency Load Disconnection Scheme during sustained over drawl at Low Frequency. In the 14th meeting of SRPC held on 27 th August 2010 had agreed to implement Automatic Load Disconnection Scheme for overdrawing constituents with the following relief: S.No. Constituents Load Relief 1 APTRANSCO 450 MW 2 KPTCL 350 MW 3 KSEB 125 MW 4 TANTRANSCO 650 MW 5 PUDUCHERRY 25 MW KPTCL had earlier informed that 350 MW of load relief through remote tripping of load under crisis period has been identified. The same is under testing and final implementation stage and would be implemented shortly. It was noted that Puducherry had provided remote tripping facilities in the identified feeders in order to provide emergency disconnection. This for the information of the PCC forum. 34

36 31. Providing synchronizing facility at Key Stations for black start restoration: The current status of synchronizing equipment installation at key stations is as follows: S.No Sync. facility requirement at Status station 1 Hubli To be provided during R & M works. However Bidnal station is having synchronous facility. Nagjhari can be synchronized at Bidnal and then supply can be extended to Hubli as a temporary arrangement. 2 Mahalingapura Provided. 3 Kayathar 110 kv To be provided by the end of August Kadra, Kodasahalli Yet to be provided DELIBERATIONS IN THE MEETING The forum requested that all the Generators needed to have synchronization facility. The forum also requested that the identified station would be provided with Synchronizing facility at the earliest. The status of provision of Synchronizing facility may be updated. 32. Protection aspects of Wind Turbines: The PCC forum had emphasized the need to examine and optimize the protection practices adopted for Wind Turbines as penetration levels are increasing. SRLDC vide Lr No SRLDC/SRC&S/Prot/2012 /4559 dt (item no 14) give the following agenda. On at 10:48Hrs one of the 110 KV wind pooling Station, 110 KV O-Tulukapatti station went dead due to CT Blast in 110 kv Kayathar O- 35

37 Tulukapatti Feeder Causing outage of about 500 MW Wind Generation. SR Frequency Dipped from about 49.60Hz to 49.00Hz.There is a need to examine and optimize the protection practices adopted for Wind Turbines as well as protection at Wind Pooling stations as the penetration levels are increasing. DELIBERATIONS IN THE MEETING The forum felt that the issue of wind turbine protection would be discussed in detail in the forth coming meeting of PCC, 33. 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. The PCC forum recommended for feasibility study for provision of Voltage control relays in the following nodes i.e. at Somanahalli, Sriperumbudur, Kalavindapattu, Almatti, Mysore etc. DELIBERATIONS IN THE MEETING CE, TANTRANSCO informed the forum that the issue needed to be discussed in the OCC forum. MS(I/c),SRPC informed that this issue had been discussed in detail in the OCC forum and the PCC members also would substantiate their views to the management for the installation of Voltage Control Relays as per IEGC. PCC RECOMMENDATIONS The forum agreed in principle for the provision of under voltage relays as mandated in IEGC Regulations to control low voltages. 36

38 The LV situation at the following nodes: Sriperumbudur, Almathy, Chittoor, Nellore, Mysore, Somanahalli, Kalavindapattu, Trichur & Hosur were noted. The status of provision of Voltage Control Relays may be updated in the next PCC. 34. Review of Talcher SPS In the meeting the review of SPS at Talcher was brought to the notice of the forum. DGM, NTPC informed that the SPS would be modified to back down all the generating units instead of tripping the units. DELIBERATIONS IN THE MEETING The forum requested NTPC to submit the details of the SPS modifications i.e over view of the scheme, SLD and the logic of the SPS. 35. Review of Deliberations of 1 st Monitoring Committee meeting and other meetings of protection subcommittee. The forum discussed the issues and recommendations made in the various meetings of protection subcommittee held between the 14 th PCC and 15 th PCC. The following meetings were held during the period from April 2012 to June 2012 and the minutes/recommendations were given as annexure. I. Spl meeting of PCC held on Annexure IX II. III. IV. Spl meeting of PCC held on Annexure X,XI Spl meeting of PCC held on Annexure XII 1 st Monitoring Committee of PCC held on Annexure XIII 37

39 I.SPL PCC( held on ) RECOMMENDATIONS & DELIBERATIONS IN THE PCC MEETING KPTCL was advised to explore the possibility of carrying out renovation at 400 KV Guttur Substation especially considering the fact that the breakers have become old. KPTCL was recommended to examine the possibility of taking 50% of the load on each bus 400 kv Guttur S/S. It was proposed to review the existing SPS at Nagjheri to take care of line loadings on Bidnal-Harthi and Hubli-Sirsi lines (action KPTCL). SRLDC may study the possibility of having split bus operation at Narendra S/S. This is in view of the fact that ICT drawl at 400 kv Narendra is low and more power is flowing in the 220 kv systems. In the 1 st Monitoring Committee meeting of PCC,SRLDC informed that preliminary studies regarding split bus at Narendra had been conducted but had not yielded satisfactory results. KPTCL informed that Narendra split bus operation was not required till December After December, split bus operation can be studied depending up on the system requirements. The simultaneous LCs of elements in the Kali Complex area should be optimized to take into account the system security. SLDC/KPTCL agreed to optimize the issue of simultaneous LCs of elements in the Kali Complex area. KPCL to undertake testing/replacement wherever applicable for the relays at RTPS & BPTS (MiCOM P437). It was observed that in respect of BPTS-Jindal line, no direct tripping was received at Jindal end though the line tripped at BPTS end on over voltage. KPCL to disable over current feature on the 400 kv BPTS-RTPS line. 38

40 II. SPL PCC( held on ) RECOMMENDATIONS & DELIBERATIONS IN THE PCC MEETING KAIGA,NPCIL ISSUES It was brought to the attention of KAIGA that the high voltage conditions prevalent in that area. It was pointed out to them that one of the reasons for high voltage was for the relatively less generation in Kaiga GS leading to lesser line loadings. The issue relating to high voltage will be put up by SRLDC in the next meeting of Standing Committee on Power System Planning. Kaiga GS was advised to ascertain the availability of space for installation of additional bus reactor. Further, Kaiga units were requested to absorb more MVAR as per the capability curves. SRLDC would obtain the details of loads etc from KPTCL for the proposed islanding scheme. The islanding scheme would be discussed in more detail during the first meeting of the Monitoring Committee proposed to be held in SRLDC during May There will be a single nodal officer to represent Kaiga I & II as well as Kaiga III & IV so as to improve the communication especially during crisis period ( i.e. Coordination between Stage-I & Stage-II of Kaiga). Nominating Single Nodal Officer at Kaiga. Reversion to original set points for protection at Kaiga As regards Single Phase Reclosure facility, NPCIL expressed certain constraints in the issue. However, Kaiga GS was requested to take up the matter in a time bound manner with the equipment manufacturer so as to ascertain the feasibility of providing this facility which would help improve the transmission availability during transient faults. Kaiga GS was requested to avail supply either through 220 kv or 400 kv for synchronization after the units have gone into house load operation. During the next outage of any of the Kaiga units, the possibility of charging the bus at Kaiga from Kadra will be explored. Kaiga GS will restore the settings of the relays at 200 kv lines since the relays were presently seeing faults up to Hubli. 39

41 Coordination of Kaiga Islanding Scheme (Action SRLDC/KPTCL/Kaiga/SRPC) Black Start Restoration Procedure mock drill and Kodasalli to extend supply to dead bus at Kaiga along with KAPS Auxiliaries. In the 15 th PCC meeting representative from Kaiga informed that status of the above issues would be intimate to the SRPC secretariat with in a weeks time. KPTCL ISSUES Provision of bus bar protection at Ambewadi Shifting of Kaiga lines to another bus bar i.e. availability of two bus bar systems at Guttur end. Positioning of ICT on each bus. While planning for the New Guttur station, as agreed in the 34 th standing committee of SR, One and half breaker scheme may be provided for the New Guttur Station. Coordination of Kaiga Islanding Scheme Strengthening of 220 kv lines from Kaiga to Kadra & Kodasalli and NJPH evacuation-possibility of re-conductoring with high ampacity conductors. Re establishing the hot line (VSAT) facility between Kaiga APS 220 KV and Karnataka SLDC. KPCL ISSUES Provision of synchronizing facility at Kadra GS (Action KPCL) Black Start Restoration Procedure mock drill and Kodasalli to extend supply to dead bus at Kaiga along with KAPS Auxiliaries. 40

42 III. SPL PCC ( held on ) RECOMMENDATIONS & DELIBERATIONS IN THE PCC MEETING 41

43 IV. RECOMMENDATIONS OF 1 st MEETING OF MONITORING COMMITTEE (held on ) & DELIBERATIONS IN THE PCC MEETING i. Provision of bus bar protection at Ambewadi S/S: KPTCL informed that R&M works contract for 220kV Ambewadi S/S had been awarded to M/s Easun Reyrolle. Bus bar protection installation is part of R&M and would be completed by December ii. Reversion to original set points for protection at Kaiga: NPCIL confirmed that Zone-1 protection of 220 kv Kaiga- Kadra and 220 kv Kaiga- Kodasalli lines at Kaiga end made 100% and Timing of Zone- 2 & 3 was revised to 300 ms & 600 ms respectively. The Zone -1 would be made 80% and Zone -2 &3 would also be revised after assessing performance during monsoon. iii. Shifting of 400kV lines at 400kV Guttur on to different buses with Bus coupler closing was carried out on The arrangement of lines is as follows: 42