SPS for JP Nigrie, MB Power and for High Loading of Sugen-Vapi S/C, held on 23.08.2017

at WRPC, Mumbai.

A meeting to design SPS for JP Nigrie, MB Power and High Loading of Sugen-Vapi S/C was conducted on 23.8.2017. MS, WRPC welcomed all the participants for the meeting. The List of

participants of the meeting is enclosed at Annexure.

A. SPS of JP Nigrie and MB Power:

JP Nigrie (2x660MW) is connected to the grid through 400kV JP Nigrie-Satna D/C (Quad conductor, 161 km each). There is no other interconnection to this station. WRLDC informed that system blackout has occurred at JP Nigrie on many occasions under N-1 contingency due to sudden high loading on the parallel circuit followed by power swing and low frequency oscillation. Also very high current was observed when one circuit is out and other circuit is under A/R and the relay has detected and tripped the line for power swing. Therefore SPS was

suggested to take care of N-1 contingency of JP Nigrie-Satna ckt.

MB Power (2x600MW) is connected to the grid through 400kV MB Power-Jabalpur PS D/C (Triple snowbird, 256km each).

There is no other interconnection to this station.

WRLDC informed that on 07/07/17, low frequency oscillations were observed at MB Power generating station under N-1 condition and the oscillation has persisted in Western Region grid for around 5 minutes. The absence of PSS and High angular separation (around 27 degree) were the two issues which has been observed at MB Power on tripping of MB Power-Jab PS one ckt. Further, in case of MB Power also there is high probability of tripping of the line in temporary fault due to power swing detection by relay. Therefore SPS was suggested to take care of N-

1 contingency of MB Power-Jab PS ckt.

MB Power was requested to take the PSS into service in consultation with the OEM immediately. MB power representative informed that there were issues of ownership transfers. However they have successfully negotiated with the transferee company of the project and the OEM and by Sept. 2017 the PSS would be

tuned and taken into service.

Conditions for SPS at JP Nigrie and MB Power stations:-

1. The SPS would be armed and kept in service whenever the generation at JP Nigrie and MB Power stations is more than 800 MW.

2. Triggering signal would be initiated for SPS action when both Main and Tie breaker position (at Nigrie/MB Power) of any of the line is OPEN for (Satna/Jabalapur PS lines respectively) OR line flow on any of the line (Nigrie- Satna /MB Power-Jabalapur PS) becomes less than 50 MW, when the generation is more than 800MW.

3. The generation to be reduced to 800 MW when one ckt is under planned shut down or as suggested by WRLDC. The SPS would be disarmed before opening the line manually. The SPS would be armed immediately after the restoration of line and the generation would be ramped up only after the SPS is armed.

4. The operators at the power station should be able to arm/disarm the SPS based on the above guidelines and the status of SPS must be clearly visible on the control panel.

5. The digital status of SPS arming/disarming signal should

also be send to WRLDC.

The logic at both these generating stations which should be implemented by JP Nigrie and MB Power is as follows:

Further, it was decided during the meeting to further explore the possibility of power swing blocking for zone 1 when one line is already out and a temporary single phase fault on the other line.

Power flow in one of the circuit is becoming lower

than 50 MW.

OR

One circuit tripping (Main and TIE CB opening at

Generating Substation)

And

If Generation at MB Power/JP Nigrie is

more than 800 MW

Reduce Generation below

800 MW with high ramp

and automated action.

This issue will be taken in the upcoming PCM in order to decide

whether any configuration is available in the relay.

B. SPS for High Loading/Tripping of 400 kV Sugen-

Vapi S/C

GETCO representative informed that during the last month, high loading of 400 kV Sugen-Vapi S/C of the order of 650-700MW was observed due the outage of Tarapur Unit 3 and 4, KAPS 1 & 2 and also outage of HVDC Mundra-Mahendragarh. Gujarat SLDC has suggested SPS in case of high loading above 750 MW or tripping of 400 kV Sugen-Vapi Line with generation reduction

at Sugen and Load shedding at DD and DNH.

WRLDC informed that following actions in real time are taken to control Sugen-Vapi loading:-

a) Maximising HVDC Chandrapur-Padghe Bipole flow.

b) Advising MSLDC to run generation at Koyna or Ghatghar.

c) Opening of 400 kV Uno Sugen-Pirana (TPL) circuit and GPEC-Jhanor when loading is more than 700 MW which provide a relief of 30-40 MW. After discussion, the following was decided:- 1. The above issue is temporary in nature and has aroused

due to outage of entire generation at TAPS and KAPS. 2. The interim arrangement done with one ckt of 400 kV

Jhanor-Navsari and one ckt of 400 kV Ukai-Kosamba to form Jhanor-Kosamba and Ukai-Navsari (Interim arrangement approved in the 36th SCM) may be restored which will relieve the loading on Sugen-Vapi and improves system reliability. The 400 kV Jhanor-Navsari D/C would be parallel path in case of tripping of 400 kV Sugen-vapi circuit and the system would be N-1 secure.

3. Further, in the 499th OCC meeting held on 22.8.17, it was informed by TAPS that their Unit 3 will be restored in Sept 2017 and unit 4 in Oct’17. This will reduce the loading of the present 400 kV Sugen –Vapi circuit to large extent.

4. In addition, in the TRM meeting of WR held on 21.8.17, PGCIL WRTS-1 informed that they will be charging the 400 kV Aurangabad(PG)-Boisar D/C in the Month of Sept’17. These circuits will attenuate the above problem

as observed presently.

In view of the above it was decided that presently there is no requirement of SPS for 400 kV Sugen-Vapi circuit. Also, it was suggested that Gujarat will restore the interim arrangement of the 400 kV Jhanor-Navsari one circuit and 400 kV Ukai-Kosamba one circuit after ascertaining that the commissioning of that 400/220 kV Kosamba ICT 4 and any other issue in the down

stream network of GETCO.

The meeting ended with thanks to the Chair.

xxxxxxx