SOUTHERN REGIONAL POWER COMMITTEE BENGALURU Minutes of the Special Meeting on the Pending Protection Issues of Puducherry Substations held on 20th July, 2018 A. Introduction A Special Meeting was held on 20th July, 2018 at PED HQ, Puducherry to deliberate on all outstanding protection issues involving their substations. The list of participants is enclosed at Annexure-I. Sh. S.R. Bhat, Member Secretary (MS), SRPC welcomed Officials of PED, NLCIL, PGCIL (SR-II) to the meeting and thanked Sh. D. Ravi, SE-I & HoD of PED for arranging the meeting at short notice. Then, outlining the reasons for calling special meeting, he stated that 230 kV substation of PED at Villianur is an important system element in grid operation. However, of late it was seen that there were three grid disturbances (30th May, 5th June and 15th June 2018) in Villianur S/S affecting all the loads connected to it. The adverse effect on the load due to the disturbance was to the extent of 100 -120 MW which is fairly sizeable and is about 35 % of the total demand of PED system. He informed that in the aftermath of the grid disturbances of 2012, Central Electricity Authority was keeping a regular watch on the grid disturbances in the country. Periodic reports were also being submitted to the Ministry of Power. Hence, three grid disturbances in fairly quick succession in PED system had attracted attention. Of the three events, the first two were discussed in the 75th meeting of PCSC held on 28.06.2018. However, owing to absence of PED representatives, these events, which primarily occurred because of failure of some substation equipment along with non-operation of required protections, could not be analysed in detail. He also stated that recognizing the importance of 230/110 kV Villianur and Bahour substations in supplying power to Puducherry, comprehensive protection audit of the same was conducted by SRPC teams in July, 2017, and a no. of measures were suggested for system improvement. However, based on the status furnished by PED, it was noted that not much progress was observed with regard to implementation of remedial measures. In view of the gravity of the matter, it was therefore decided to convene this meeting to analyze these Grid Disturbances in detail, to review the status of implementation protection audit remarks of Villanur & Bahour substations, and to identify various short-term and long-term measures for time-bound implementation in the interest of smooth grid operation. Minutes of the Special Meeting on Pending Protection Issues of Puducherry Stations held on 20th July, 2018 Page 1 B. Analysis of the Villianur GD’s on 30.05.2018, 05.06.2018 & 15.06.2018 The Grid Disturbances that occurred on 30.05.2018, 05.06.2018 & 15.06.2018 at 230/ 110 kV Villianur Substation were thoroughly analysed in the meeting. Their analysis, along with necessary measures required to be taken by various partied involved, is enclosed at Annexure-II for kind reference. The details of the tripping events including relevant PMU plots presented by SRLDC in the meeting are also enclosed at Annexure-V for kind reference. PED, PGCIL (SR-II) and NLCIL were requested to initiate necessary action to comply with the measures recommended. C. Review of status of implementation of Protection Audit Recommendations of Villanur and Bahour Substations. Subsequent to a similar GD event at 230/ 110 kV Villianur SS on 19.05.2017 (triggering incident in this case was failure of CT in 110 kV Villianur-Kurumbapet), comprehensive protection audit of 230/ 110 kV Villinaur SS and 230/ 110 kV Bahour SS was conducted by SRPC teams in July, 2017, and a no. of recommendations were given for system improvement. Based on the status furnished by PED vide their mail dated 10.07.2018, implementation status of above remarks was reviewed in the meeting, and the same is enclosed at Annexure-III for kind reference. It was noted that even though implementation of majority of the remarks is linked with PSDF funding, there is a significant chunk of remarks which have no financial implications, but solely related to revising existing relay settings, and could have been attended by this time. PED was therefore asked to attend the latter set of remarks on priority basis in a month’s time. Further, since various works had already been commenced through PSDF funding, PED was asked to complete the remaining remarks also in a phased and time-bound manner. D. Review of compliance status of the recommendations given in the special meeting held on 3rd January, 2017 w.r.t. Neyveli Grid Disturbance on 25.11.2016 In the meeting, the compliance status of the recommendations given in the Special Meeting held on 3rd January, 2017 w.r.t. Neyveli Grid Disturbance on 25.11.2016 was reviewed, and the same is enclosed at Annexure-IV for kind reference & necessary action by PED, NLCIL & TANTRANSCO. It was noted that TANTRANSCO representatives had not come to attend the meeting. Minutes of the Special Meeting on Pending Protection Issues of Puducherry Stations held on 20th July, 2018 Page 2 E. Measures identified for time-bound implementation of various protection remarks by PED While appreciating the steps and constraints expressed by PED, the following measures were highlighted for time bound and focused implementation: Since the protection systems in place at Villianur & Bahour substations are not in compliance of various protection standards & regulations, early & time-bound implementation of the ongoing schemes for renovation and up-gradation of substations through the Power System Development Fund was emphasized. In the Review Meeting of PSDF held in January 2018, Chairperson, CEA had expressed concern over the slow pace of implementation. PED had also been requested to kindly step up the pace of implementation. It was noted that PED is in the process of submitting a revised DPR for additional PSDF funding to undertake further works for improving protection systems at Villianur & Bahour substations. However, since considerable time had lapsed since the Review Meeting in January 2018, PED was asked to expedite the same. It was noted that at present PED is dependent on external agencies for carrying out testing of various electrical equipment & relays & protection oriented trouble shooting. Similarly, over-dependence on TANTRANSCO engineers was hampering the works. PED was therefore requested to initiate steps to suitably develop manpower of PED in various activities such as relay setting calculations etc. or alternatively, approach central PSU such as POWERGRID, who would undertake the works on consultancy basis. The necessity of establishing Standard Testing Lab and procurement of essential testing equipments to cater to all 230 kV substations under PED control was high-lighted. PED was asked to ensure regular participation of their Officers in the Sub-Committee Meetings of SRPC, especially those relating to Protection. In view of the criticality of Villianur & Bahour substations, PED was also asked to identify a Nodal Officer at senior level to make periodic assessment of status of implementation of their protection audit remarks, and take steps to remove any bottlenecks by bringing them to the notice of their higher management for efficient redressal. F. Vote of Thanks MS, SRPC thanked SE-I & HoD, PED and other Officials from Puducherry ED, NLCIL, PGCIL (SR-II) & SRLDC for participating in the Meeting. He hoped that with active co-operation & due diligence by PED, measures as chalked out would be given priority for improving protection systems at Puducherry Substations, and effective monitoring mechanisms would be put in place to improve their operational performance. ***** Minutes of the Special Meeting on Pending Protection Issues of Puducherry Stations held on 20th July, 2018 Page 3 Annexure-I Annexure-II Analysis of the Villianur GD’s on 30.05.2018, 05.06.2018 & 15.06.2018 Sl. Details of Event Date &Time Reason Remarks Category No. Triggering incident was failure of 230 kV side R-ph CT of 230/ 110 kV of ICT -2 at 230/ 110 kV Villianur station. 230 Complete outage of 08:40 hrs on kV Neyveli - Villanur and 230 kV Pondy - Load Loss: 1 230/ 110 kV Villianur GD-1 30-05-2018 Villianur lines tripped from Neyvelli end 130 MW Substation and Pondycherry end respectively. This led to loss of supply to 230 kV Villianur Station. Stipulated TR formats were not used by PED and NLCIL SLD: The single line diagram of 230/ 110 kV Villianur SS as furnished by PED is attached at the end. Tripping of 230 kV Villianur – NLC-II line: NLC-II (NLCIL) end: As per FIR/DR/EL/TR, line tripped at 08:50:00.544 hrs due to operation of SOTF O/C protection. Time-sync of Protection Relays with GPS needed to be ensured at NLC-II. Villanur (PED) end: As per FIR, the line was kept holding from Villianur end. It was stated in TR that 230 kV R-ph HV-II CT of 100 MVA Auto Transformer-II failed resulting in tripping of both 230 kV Villanur – NLC2 line and 230 kV Villianur-Pondy line from remote ends. The respective breakers at Villianur 230 KV SS end were holding and only the breakers at Neyveli and Pondy ends got tripped. Tripping of 230 kV Villanur – Pondicherry line: Pondycherry (PGCIL-SR2) end: As per FIR/DR/EL/TR, line tripped at 08:42:23.564 hrs due to DPR, Z2 (with Tz2 = 250 msec) operation. Villanur (PED) end: As per FIR, the line was kept holding from Villianur end. It was stated in TR that 230 kV R-ph HV-II CT of 100 MVA Auto Transformer-II failed resulting in the tripping of both 230 kV Neyveli - Villanur line and 230 kV Pondy - Villianur line.