80th OCC Minutes Final

8/13/2019 80th OCC Minutes Final

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Minutes of 80thOCC meeting held on 10thDecember, 2012 at Guwahati

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iv) System frequencyremained within permissible range of 49.5 Hz to 50.2 Hz for86.14 % of the time, below 49.5 Hz for 3.26 % and above 50.2 Hz for 10.60 % of

the time as compared to 90.65 %, 2.07% and 7.28 % respectively in the previous

month.

v) Regional peakdemand in November, 2012 was 1921 MW as compared to 1927MW in October, 2012, a decrease of 0.31 % over the previous month.

vi) Regional peak availability was 1815 MW as compared to 1864 MW in previousmonth, a decrease of 2.63 % over the previous month.

vii)Energy requirementwas 943.86 MUs in November, 2012 compared to 1029.17MUs in October, 2012, a decrease of 8.29 % over the previous month.

viii)Regional energy availabilitywas 882.75 MUs compared to 969.09 MUs in theprevious month, a decrease of 8.91 % over the previous month.

ix) Rise in demand met was recorded in Meghalaya (7.95%), Manipur (3.31%), Ar.Pradesh (1.80%), Mizoram (0.82%) & Assam (0.64%) over the previous month.

x) Drop in demand met was recorded in Tripura (15.52%) & Nagaland (14.69%)over the previous month viz. October, 2012.

xi) Over Voltages at 400 kV substations were observed at Misa where maximumvoltage observed was 424 kV. No over voltage at 220 kV S/S was observed.

xii)No over Voltages were observed at 132 kV S/S.xiii)No under Voltages were observed at 400 kV S/S, 220 kV S/S. Under voltage,

observed at 132 kV S/S at Aizawl, was 120 kV.

xiv)Regional Generation & Inter-regional Exchanges during the month ofNovember, 2012 compared to October, 2012 are given below:

SN Parameter November, 2012 October, 2012

REGIONAL GENERATION & INTER REGIONAL EXCHANGES (in MU)

1 Total Generation in NER (Gross) 691.344 961.075

2

Total Central Sector Generation (Gross) 405.132 572.459

Total State Sector Generation (Gross) 286.212 388.616

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Inter-Regional Energy Exchanges

(a) NER - ER 1.23 50.43

(b) ER - NER 216.61 65.39

(c) Net Import 215.38 14.96

Th e Sub -comm i t t ee no t ed a s above.


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FOLLOW UP ACTION

C.1 Early revival of 3 numbers of 20 MVA Transformers at KopiliAssam observed that right from the time of the commissioning of 160 MVA Auto

transformer of Power Grid at Kopili, the existing 3 numbers of 20 MVA, single phase

transformers supplied by NEEPCO are not in working condition till today.

Therefore, NEEPCO was requested to make necessary arrangement for revival of the

above transformers for strengthening of the grid security at an early date.

The NEEPCO representative had informed that the above said transformers were

not charged since March, 2011.

The committee had suggested NEEPCO to keep the 3X 20 MVA transformers in

charged condition so that it could be connected to grid in case of outage of 160

MVA Autotransformer.

During 75th OCC meeting, NEEPCO stated that after completion of Shutdown of

Kopili-Khandong line, the transformers would be test charged after necessary oil

filtration.

During 76thOCC meeting, NEEPCO had informed that the oil filtration work would

be completed within seven (7) days. Further, the Committee had requested

POWERGRID to study parallel operation of the 3x20 MVA transformers with the

existing Kopili ICT.

NEEPCO informed that the 3x30 MVA Transformers was successfully charged from

220 kV side on 8thSeptember, 2012.

During 77th

OCC meeting, the Committee inquired from NEEPCO about thepercentage impedance of both transformers. NEEPCO agreed to provide the

information in the next OCC meeting.

The Committee agreed and requested POWERGRID to explore the possibility for

utilizing these transformers as these are regional assets and cannot be kept idle. It

was also decided that possibility will be explored for charging the ICT along with


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132 kV Kopili Khandong ckt-I in the event of shut down of 132 kV Kopili

Khandong ckt-II.

During 78thOCC meeting, NEEPCO submitted the percentage impedance of 3x20

MVA transformers to the committee. The committee requested POWERGRID to

compare the percentage impedance of 3x20 MVA transformers with the existing 160MVA ICTs and explore the possibility of parallel operation of both the transformer

banks.

During 79thOCC meeting, POWERGRID had informed that they have compared the

percentage impedance of 3x20 MVA transformers with the existing 160 MVA ICT

and found it to be within permissible limit. The vector group of the banks was to be

checked to explore the possibility of parallel operation of 3x20 MVA transformers

with the existing Kopili ICT. The committee had requested POWERGRID andNEEPCO to make the necessary arrangement/tests required to check the possibility

of parallel operation.

The representative of NEEPCO requested NERPC Secretariat to write to their

management to explore the possibility of parallel operation after carrying out

necessary tests in association with PGCIL. The committee agreed.

Th e sub -Comm i t t ee no t ed as a bove.

C.2 Synchronization of Pallatana Module -IIn the meeting on 24.07.12 OTPC had informed that U-I will be put on commercial

operation in the last week of August, 2012. For this continuous running of the unit

at full capacity (363 MW) will be required for 72 hrs. It was decided that the matter

will be deliberated in next (76th) OCC meeting for finalizing quantum of backing

down required at different stations in 132 kV pocket and acceptance of the utilities

in this regard for finalization of modus operandi.

During 76thOCC meeting, NERLDC presented the detail system study report for 72

hours continuous run Pallatana module-I. The detail study was carried out for two

cases: Off-Peak (03:00 Hours) and Peak (20:00 Hours) based on evacuation of

maximum power up to 350 MW and case study of tripping of Pallatana module.


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From the report it was found that during off-peak hours Tripura, AGTPP and

Loktak has to back down their generations.

On telephonic discussion with OTPC during the OCC meeting, it was understood

that Palatana unit-I would start trial run from mid August and about 30-40 MW

will be injected to Grid as Infirm power. Thereafter, 72 hrs full load pre-

commissioning test was expected to be done by mid September. About 363 MW

continuous load would have to be injected to the NER grid during such test by

reducing Tripura state generation, AGTPP and LOKTAK generation.

AGM, TSECL stated that beneficiary state would be required to overdraw power as

their drawl scheduled will be reduced to the extent AGTPP and LOKTAK generation

is backed down. In addition Tripura would have to maximize their drawal with

backing down of own State generation. In view of above it was decided to haveseparate meeting to study the pre-commissioning test arrangement and

commercial impact of affected utility. Further, it was discussed that with the

commissioning of Palatana project fault level of 132 KV pocket of NER would

substantially go high. Existing protection system and impact of likely fault at

various condition of Palatana operation would have to be studied at Transmission

network and Generating stations connected at 132 KV pocket of both state and

central sector. It was decided that PGCIL would conduct required study and report

would be placed to next combined OCC and protection committee meeting.

POWERGRID had agreed.

During 76th OCC meeting, the committee expressed concern about the non-

representation of OTPC in the OCC meeting and felt that this issue should be

deliberated in the presence of OTPC representatives in the next OCC meeting.

During 77th OCC Meeting, DGM, OTPC informed that the gas turbine firing has

started on 13.09.12 and the machine will be synchronized to the grid on 29th

September, 2012 after passing through various stages of operation as per the

manufacturers guidelines. After synchronization infirm power of about 40 MW

(approximately) will be injected into the grid. Then machine will run on Full Speed

No Load (FSNL) for seven (days). After that steam turbine rolling will start and the

module I will come into operation w.e.f. 29.09.2012. Since there is no bypass

arrangement in the modules, the machine cannot run under open cycle mode. In


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initial phase, the complete module will generate around 150-160 MW and slowly

generation will ramp upto 363 MW, and ultimately machine has to run

continuously under full load for 72 hours to declare COD.

During 77thOCC meeting, NERLDC gave the detail presentation for evacuation of

maximum power from Pallatana taking into account the surge impedance loading

of the line as limitation, as advised by NLDC after grid disturbance. The detail

study was carried out for following scenarios:

1. Evacuation of Maximum power from Pallatana during 0300 Hrs withoutbacking down of other generation

2. Evacuation of 360 MW (Ex-PP) from Pallatana during 0300 Hrs with backingdown of other generation

3. Case study on Reduction of generation of Pallatana from 360 MW during0300 Hrs

4. Case study on tripping of 360 MW (ex-PP) generation at Pallatana GBPPduring 0300 Hrs

5. Evacuation of Maximum power from Pallatana during Peak Hrs withoutbacking down of other generation

6. Evacuation of 360 MW (Ex-PP) from Pallatana during Peak Hrs with backingdown of other generation

7. Case study on Reduction of generation of Pallatana from 360 MW duringPEAK hours

8. Case study on Tripping of Palatana GBPP during Peak Hrs from an initialgeneration of 360 MW)

During the presentation by NERLDC, it was observed that in absence of 400kV

Silchar-Byrnihat line, tripping of machine at Palatana under full load condition

(i.e.363MW), during peak and off peak hours, will have adverse impact on the NER

system leading to overloading of number of lines and ICT at Misa. Further,

NERLDC requested Assam and Meghalaya that 132 kV Panchgram-Lumshnong

line should be ready before the synchronization of the Pallatana Machine on

29/09/12. Assam informed that 90% of Assam portion is ready and the rest will be

completed very soon. MeECL informed that they would communicate the actual

progress after getting information from the site.


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AGM, TSECL informed that during trial operation NERLDC should check whether

the 132 kV NER system can sustain generation of 200 MW and more. Further, he

suggested that the machine may be synchronized with grid and during the

operation close co-ordination with NERLDC is required and there should be proper

Load-Generation Stabilization.

Assam emphasized that the NER system cannot sustain generation of 363 MW

from Palatana without commissioning of 400 kV Silchar-Byrnihat line. So, we have

to wait for commissioning of this line and we should go step by step for

synchronization with the grid with full generation of 363MW. However, OTPC can

generate 200 MW as decided in previous meetings till 400kV Silchar-Byrnihat line

is ready.

POWERGRID informed that the commissioning schedule of 400 kV Silchar

Byrnihat is January, 2013.

CEA representative stated that at present NER system is not strong enough to take

the full generation of OTPC and as per CEA guidelines commercial operation of

machine can be declared only after 72 hours of continuous generation under full

load condition. So, OTPC should wait till the commissioning of 400kV Silchar-

Byrnihat line. The injected power will be infirm power, if COD is not granted.

After detailed deliberation the Committee agreed to allow for synchronization of

Pallatana Machine with ex-bus generation of 200 MW due to system constraint.

After stabilization of machine and proper synchronization with the grid, full loading

upto 360 MW would be considered.

But the representative of OTPC informed that as a technical requirement for trail

run, the machine needs to go upto full load of 363MW and COD cannot be

declared without continuous operation under full load for 72 hours.

During 77th OCC meeting, taking into account the prevailing situation and

requirement of additional power in coming Durga Puja, the Committee ultimately

agreed with OTPCs proposal to go for synchronization process and continuous


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operation under full load for 72 hours required for declaration of COD subject to

OPTC provide their detail action plan to NERLDC well in advance so that necessary

planning for backing down of generation and change in drawl schedule of

constituents can be finalized by NERLDC before hand as the existing transmission

system is not healthy to absorb any abnormality due to tripping of Palatana

generating Unit, while running under full load (363MW).

During 78th OCC meeting, NERLDC made a presentation highlighting various

provisions in CERC / CEA Regulations and summarized the non-compliances

pertaining to synchronization of Generating unit at Palatana. The following non-

compliances were observed during discussion:

1. Required clearance/ approval from Regional Inspectorate of CEA was notavailable as per requirement CEAs safety regulations.

2. Application for seeking connection to ISTS and connection offer letter notmade available to RLDC/RPC along with tripartite agreement.

3. One month advance notice of likely date of synchronization, likely quantumand period of injection of infirm power as per 6.3 of connectivity procedures

not complied with.

4. Treatment of merchant quantum not furnished which will be needed for fullload operation.

5. Data and communication facilities with NERLDC for transfer of real timeoperational data (such as voltage, frequency, real & reactive power flow,

energy, status of CB, isolators and transformer taps etc.) are yet to be

established.

6. SPS / islanding scheme yet to be in place.

All the above six non-complianceswere discussed in detail.

Point 1: OTPC informed that clearance from RIO will be ensured beforesynchronization to Grid.

Point 2: OTPC informed that the said documents will be sent to NERLDC/NERPC at

the earliest.

Point 3: OTPC representative stated that schedule of commissioning was being

discussed in various forums for quite some time and based on this clause,


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OTPC representative did not agree to go for testing / synchronization process with

limited generation of 200 MW as DLN tuning requires minimum 300 MW

continuously for ten (10) hours and 350 MW for two (2) days. Further, OTPC

informed that unless the machine is run with full load, its technical capability

including emission level cannot be ensured and it is not advisable to accept

machine from the supplier/manufacturer. OTPC also desired continuous running of

machine for 72 hours under full load to avail the COD.

ASEB representative stated that Palatana should be allowed to synchronize their

machine with the grid and load may be allowed considering system condition.

Tripura representative stated that there should be firm schedule from OTPC so that

all constituents can take necessary action.

NERLDC representative re-emphasised that any generation beyond 200/150 MW,

even after stabilization, would involve serious compromise on grid security in the

absence of SPS/islanding scheme which are yet to be in place. Moreover, injection

to grid beyond this level would require backing down of own generation by Tripura,

Mizoram, NEEPCO (from AGTPP) and NHPC (from Loktak) and tripping of unit

under full load could cause severe grid disturbance.

Tripura and Assam agreed to back down their generation and allow OTPC to inject

power to the maximum extent possible without endangering the grid although it willhave commercial implication/burden on the constituents. NEEPCO and NHPC

stated that for backing down of their units they require in advance schedule and

quantum. NEEPCO stressed that their injection to the grid from AGTPP should be

steady. Constituents insisted for detailed schedule of injection to the grid in

advance so that NERLDC can plan accordingly.

OTPC stated that they would submit hourly schedule of injection at least two days

in advance to NERLDC.

After detailed deliberation in the 78thOCC meeting the following were decided:

i) OTPC would be allowed to synchronize their machine only after compliance ofthe stipulations in Point Nos. 1, 2, 4 and 5 above.

ii) NERPC Secretariat would be informed about the compliance status of the abovefour points by NERLDC.


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iii) OTPC would submit proposed hourly schedule of infirm power to NERLDC witha copy to NERPC Secretariat at least two days in advance.

iv) NERLDC would issue final clearance to OTPC in consultation with NERPCSecretariat considering real time grid conditions.

v) OTPC would strictly adhere to NERLDC instruction in real time and regulategeneration accordingly.

vi) There should not be any variation in injection of power by OTPC during Durgapuja (period 20/10/12 to 25/10/12) and steady generation would be

maintained as advised by NERLDC.

vii)The sub-committee agreed to allow OTPC to inject power to the maximumextent possible without endangering the grid.

viii)Commercial implications associated with Pallatana generation would be wouldbe in line with CERC Regulations and decision of RPC forum.

During 79thOCC meeting, AGM, NERLDC informed that OTPC had synchronized

their machine and generated around 30 MW during Durga Puja which was of great

help to NER grid during puja.

During 79th OCC meeting, GM, OTPC had informed that to ensure capability of

plant and various equipment, auxiliaries & ancillaries associated with Block-1 /

Unit-1 of Pallatana Generating station, trial operation is required with increase of

loads in steps as per schedule and after unit stabilization run, machine needs to berun at full / base load and the continuous run of unit for minimum period of 72

hours is required for declaration of COD. SE(Com) informed that for declaration of

COD, the running of machine continuously for 72 Hrs is not a mandatory

requirement. But as per PPA of OTPC with the constituent states of NER, each

block/unit is to operate seventy two (72) consecutive hours at or above 95% of the

contracted capacity. OTPC had informed that after running of Block-1

continuously for 72hrs. at full / base load, the machine could be run at reduced

load for fifteen (15) days. The running of Unit at full / base load is required to

demonstrate gross generation, heat rate, auxiliary consumption, and NOX level

including capability & reliability of various equipment, auxiliaries, ancillaries and

associated control and protection system.

AGM, NERLDC stated that all tests required for commissioning of Pallatana U#1

will be facilitated by NERLDC as agreed in previous OCC meetings but the


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commercial issues with the stake holders i.e. NEEPCO/NHPC/Tripura have to be

settled by OTPC.

POWERGRID informed that 400 kV Silchar- Pallatana-II tripped number of times on

07/11/12 on overvoltage due to some problem at OTPC end, the same needs to be

checked.

OTPC informed that the investigation is going on and it will be rectified soon.

NERLDC also informed that as per the previous decision in OCC meeting all

constituents had agreed for 72 hours of continuous run of Palltana U#1 at full load

(i.e. 300 MW). For evacuation of full generation of Pallatana U#1, Tripura, Assam,

NEEPCo and NHPC have to back down their generation. Therefore, if OTPC requires

continuous load more than 72 hours (3 days), all constituents should agree for

such transaction and the commercial issues also needs to be resolved beforehand.

NERPC had given a presentation on the commercial implication of backing down of

generation by NHPC, NEEPCO, Tripura, and Mizoram due to injection of generation

by Unit-1 of Pallatana taking into account the previous load flow study on case to

case basis.

Assam stated that backing down of generation may be allowed, but frequent

ramping up/down of generation is not desirable as it may lead to cascading effect

resulting in a grid disturbance. Further they stated that the generation status at

Pallatana should be integrated with the SCADA system of all SLDCs.

Tripura also stated that the commercial implication should be settled beforehand.

NEEPCO also informed that for running of Unit-1 for more than 72 hours, prior

approval from their management would be required. NEEPCO requested for steadyinjection of power for the whole day to manage their gas supply. OTPC informed

that it is difficult to maintain steady injection of power to the grid during trial

operation.

OTPC informed that since all constituents are not agreeing for full load generation

for 15 days, reduced generation of 250-280MW may be allowed after continuous

run of Unit-1 for 72 hrs. at full / base load.


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During discussion POWERGRID was requested to inform the committee about the

present status of 400kV Silchar Byrnihat line and the 400kV substation at

Byrnihat. Committee requested for commissioning of line and substation by the end

of November 2012. But POWERGRID informed that it is difficult to commission the

GIS substation before December 2012.

In the 79th OCC meeting, after detailed deliberation the committee reiterated its

earlier decision to allow continuous run of the Unit-1 for 72 hours at full load.

Further OTPC should furnish its schedule at least 48Hrs beforehand to enable all

the stake holders to carry out proper planning. However, the commercial matter

regarding running of Unit-1 beyond 72 hours at full / reduced load needs to be

discussed in commercial committee and NERPC meeting to settle the commercial

implications.

Del i b e r a t i o n o f t h e comm i t t e e

Committee requested POWERGRID to inform the house about the status of 400kV

Silchar Byrnihat line and the 400kV substation at Byrnihat. POWERGRID

informed the committee that the stringing work of 400kV Silchar Byrnihat line is

under progress and is likely to be completed by January, 2013. Regarding 400kV

GIS substation at Byrnihat it was informed that Reactor oil filteration is in progress

and one transformer has also reached the site. The pre-commissioning tests will be

completed as early as possible. The commissioning of 400kV GIS cannot be

completed before January, 2013 although most of the erection commissioning

activities on 220kV side will be completed by December, 2012.

GM (Plant), OTPC informed that synchronization of Unit -1 would be done again on

14.12.12 for further tests and COD and submitted the schedule to NERLDC. The

committee deliberated the generation schedule of OTPC Pallatana w.e.f. 14.12.12

and after detail discussion it was decided that:

i) On 14.12.12 OTPC should synchronize Unit-1 before Peak Hours (i.e. 17:00Hrs) and the generation should be in the range of 50 to 80 MW so that it will

help NER grid during Peak hours and moreover, start-up power should be

drawn from the Grid during off-peak hours, which will help the TSECL system.

Afterwards the load may be increased gradually.


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ii) On 15.12.12 OTPC should plan to generate about 300 MW (for 2 hours) duringPeak hours so that such quantum of generation can be easily accommodated.

iii) From 15.12.12 to 24.12.12 OTPC should generate around 230 to 250 MWcontinuously. However, the generation needs to be rescheduled, if required,

depending on real time grid conditions and as per the advice of NERLDC.

iv) If OTPCs generation would be found to be stable, then generation of 230 to 250MW can be continued further till 02.01.2013 to support the grid during

Christmas and New Year eve.

v) From 03.01.2013 onwards, OTPC may plan for generation of 363 MW (fullload/base load) continuously for 72 hours in consultation with NERLDC.


C.3 SPS scheme for PallatanaIt was observed from load flow studies carried out by NERLDC that tripping of

Pallatana unit during peak hours would cause loading of Kopili ICT (160 MVA). To

save the situation shedding of around 100 MW of load would be required in the

132 KV pocket through SPS.

During 76thOCC meeting, DGM, NERLDC had informed that a special protection

scheme is required to be planned for shedding the above load. The committee

advised NERPC Secretariat to design the SPS in consultation with NERLDC,

Assam, Meghalaya, Tripura, NEEPCO, NHPC and OTPC.

POWERGRID representatives had informed that not only SPS but protection

schemes are also required to be reviewed before commissioning of Pallatana GBPP.

From the load flow study it was observed that in certain lines there will be reverse

flow of power due to tripping of Pallatana.

The committee had requested POWERGRID to study the protection schemes and

prepare a report. The same will be discussed in the next OCC meeting.

During 77th OCC meeting, DGM, NERLDC stated that in case of tripping of

Pallatana unit, around 120 MW load shedding through SPS would be required in


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Mizoram, Tripura and South Assam (each 40 MW) and some load shedding would

be required in Meghalaya. POWERGRID informed that the implementation of SPS

for tripping of far off lines/loads will be difficult as there will be co-ordination

problem because of non-availability of communication links and NERLDC should

find some other nearby lines or SPS can be linked with Kopili ICT. NERLDC

informed that they have identified the list of radial lines in NER system for

disconnecting during emergency conditions to save the grid. They pointed out that

the SPS can be implemented on those lines which are available in 132 kV Pocket.

All the constituents agreed for implementation of SPS on these lines and also for

emergency disconnection of listed lines in case of necessity.

The committee felt that the SPS scheme is required to be in place at least before

the synchronization of Pallatana unit. After detailed deliberation committee

requested NERLDC to prepare the SPS scheme of Pallatana in consultation withNERPC and POWERGRID.

During 79th OCC meeting, NERLDC informed that lines have been identified in

NER system for disconnection during emergency conditions to save the grid. SPS

can be planned accordingly. The committee requested NERLDC to give the list of

lines associated with tripping of Unit-1 at Pallatana and POWERGRID was

requested to plan the implementation of the SPS scheme.

The committee felt that NERPC, NERLDC and POWERGRID may discuss the

matter and plan accordingly for implementation of SPS scheme.


C.4 Implementation of islanding scheme in NERFor survival of different parts/pockets (with identified generation along with some

load) of NER grid in the event of grid disturbance, islanding schemes are required

to be planned properly & implemented.

DGM, NERLDC stated that some islanding schemes need to be planned so that the

islands survive during any grid disturbance so that start-up power can be

extended to other generating stations.


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During 77thOCC meeting, the islanding scheme for NER was discussed in detail

for separating of NER system from NEW grid and forming of islands in NER. Two

proposals for islanding scheme were discussed.

In both proposals, first step is isolation of NER from NEW Grid at a particular

frequency by tripping of 400kV D/C line and 220kV D/C line connecting ER and

NER. In one case it has been proposed for formation of two Sustainable Small

System (SSS) and then Unit islanding and ultimately Safe shutdown of Generating

units when frequency falls to different levels. The frequency level at which actions

are to be initiated is to be finalized after discussion.

The Committee requested all the constituents to study the islanding schemes and

communicate their comments/suggestions at the earliest so that the islanding

scheme for NER can be finalized.

Further, DGM, NERLDC informed that the list of radial lines in NER system, which

can be tripped during emergency to save the grid, have been identified. During

emergency there may not be time to co-ordinate with SLDC (like written message

etc.) before taking such action. However, formal communication shall be made by

NERLDC afterwards.

During 79thOCC meeting, the committee felt that further study is required before

finalizing the islanding scheme for NER. The committee requested all the NER

constituents to study their systems and give suggestions/comments, if any before

finalization of the same. All constituents agreed.

MS I/C stated that the frequency level at which actions are to be initiated, location

of UFR & df/dt relays and communication link required etc. needs to be studied for

implementation of islanding scheme. The committee suggested that NERPC,

NERLDC and POWERGRID may discuss and plan accordingly for implementation.



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C.5 Independent third party audit of protection system and self-certification inrespect of operationalisation of Under Frequency Relay (UFR) and df/dtrelay

The Chairperson, CEA vide his D.O letter No. 7/AI/GD/GM/2012/397-407,

addressed to Honble Chairperson, NERPC had requested for completion ofindependent third party audit of protection system and to ensure operationalisation

of Under Frequency Relay (UFR) and df/dt relay based automatic load shedding

within one month. In response to above letter NERPC vide letter No.

NERPC/OP/OCC/2012/5687-702 had circulated extract of CEA & CERC

regulation and some formats, with typical example (which can be downloaded from

NERPC website), to help in collecting various information. No. of groups need to be

formed to carry out the protection audit. The action plan needs to be discussed so

that the work can be completed as early as possible.

However, the self-certification (by STUs / CTU) in respect of operationalisation of

Under Frequency Relay (UFR) and df/dt relay based automatic load shedding may

please be submitted in the prescribed format to NERPC and CEA at the earliest.

During 79thOCC meeting, SE (Comml), NERPC informed that as recommended by

Enquiry Committee, the third party independent audit for the Protection systems in

NER is to be completed as early as possible and presently Ministry of Power and

CEA are also monitoring the progress in various regions it very closely. Therefore,

for the benefit of the NER, the upgradation of protection system is very much

required for smooth and reliable operation of grid and action should be initiated at

the earliest. Further, he informed that third party independent audit of Protection

systems for Northern region has already been completed by PGCIL in association

with CPRI and other regions have also started their action plan. He informed that in

NER there are about 135 Nos. of substations/ generating stations of 132kV and

above voltage class and also proposed to carryout protection audit for all these

substations / generating stations as 132kV system forms the backbone of NER

unlike other regions. Since arrangement of funds is the major constraint in NE

region, small groups /teams have to be formed taking representation from NER

constituents. The committee decided to form teams comprising of four (4) members

from different state utilities/owner, PGCIL/NEEPCO/NHPC and NERPC/NERLDC.


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NERPC will co-ordinate the audit and prepare the further course of action in

consultation with NERLDC and POWERGRID. The nominated member of

NERPC/NERLDC will be the co-ordinator of each group.

Further, NERPC, in consultation with POWERGRID and NERLDC, had prepared the

detailed plan for carrying out the audit of protection system of all 132 kV and above

voltage class substations/generating stations in NER. NERPC vide letter dated 26th

November, 2012 and 30th November, 2012 had requested PGCIL and other

constituents to provide logistic support inform of road transport and stay at various

places in NER.

Member Secretary I/C, NERPC informed that ED, POWERGRID has agreed to

provide required support for carrying out the audit of protection system. He also

informed that the protection audit for Tripura is likely to be completed before

Christmas and from second week of January, 2013, other teams will proceed for the

audit and entire audit is likely to be completed by February, 2013. Further, he

requested all the constituents to nominate their representatives for the audit.

Assam submitted their nominations for audit team. Other constituents agreed to

nominate their persons for audit team. After detail deliberation all the constituents

agreed to the proposed dates and to extend their supports to complete the audit in

time bound manner.


C.6 Details of Installations and self-certification (by STUs and CTUs) in respectof operationalisation of Under Frequency Relays (UFRs) in NER systems andadditional requirement of UFR and df/dt relays:

During 79thOCC, Manipur had informed that the UFRs have been installed on 33

kV Yurembum-Limukhong radial feeder as advised by the committee. In the

process installation of all UFRs in the NER has been completed as per earlier

decision of the committee. Further all constituents (STUs and CTUs) were

requested to furnish the relevant information in the format prescribed by CEA. It

was also discussed that the requirement of UFR and df/dt relays need to be

reviewed based on the recommendation of the enquiry Committee constituted by

the Ministry of Power headed by Chairperson CEA.


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MS (I/C) informed that after the grid disturbance, the Ministry of Power and CEA

are closely monitoring the progress in implementation of recommendations of

Enquiry Committee. CEA is also asking the operation details of UFRs every now and

then. Therefore, all constituents are requested to submit the requisite data at the

earliest. Constituents, who have not submitted the required information, have

agreed to submit the same at the earliest. Further, he informed that the frequency

band has been tightened further by CERC to 49.7 to 50.2, therefore the frequency

settings and load relief is further required to be reviewed.


D. N E W I T E M S

D.1 Proforma for Operational Statistics

The operational Statistics as given below was not furnished in the meeting.

(i) Schedule Vs Actual Generation.

(ii) Peak Demand: Schedule Vs Actual.

(iii) Integrated Operation of the system.

(iv) Details of DC, schedules and injections from Central sector stations, drawalschedules and entitlements of constituents.

(v) Details of major reservoirs in NER.

Th e oper a t i o n a l s t a t i c s wer e shown i n t h e p r e sen t a t i o n b y NERLDC.



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D.2 State-wise anticipated peak demand/requirement, shortage for December-2012, January, February, March & April- 2013.

Th e s u b-Comm i t t ee r evi ew e d & f i n a l i z ed t h e a n t i c i p a t e d p ea k

d emand / en e r g y r eq u i r emen t / Av a i l a b i l i t y (w i t h o u t Pa l l a t a n a g en e r a t i o n ) f o r

t h e mon t h s of Decem ber -2 0 12 t o Ap r i l -2 0 13 .

A. Peak Demand

B. Peak Availability

Th e Comm i t t ee no t ed a s above .

S.No. State

Peak

Demand

(MW)

Dec 12

Peak

Demand

(MW)

Jan 13

Peak

Demand

(MW)

Feb 13

Peak

Demand

(MW)

Mar 13

Peak

Demand

(MW)

Apr 13

1 Ar. Pradesh 100 105 105 105 110

2 Assam 1175 1200 1210 1230 1250

3 Manipur 100 105 105 100 110

4 Meghalaya 280 280 280 280 290

5 Mizoram 75 75 75 70 75

6 Nagaland 100 110 115 110 120

7 Tripura 240 240 230 230 240

Region 2070 2115 2120 2125 2195

S.No. State

Peak

Availability

(MW)

Dec 12

Peak

Availability

(MW)

Jan 13

Peak

Availability

(MW)

Feb 13

Peak

Availability

(MW)

Mar 13

Peak

Availability

(MW)

Apr 13

1 Ar. Pradesh 85 80 75 70 65

2 Assam 970 950 920 900 850

3 Manipur 85 80 75 70 70

4 Meghalaya 195 190 180 175 170

5 Mizoram 60 60 55 50 45

6 Nagaland 90 85 75 75 75

7 Tripura 160 155 145 140 130

Region 1645 1600 1525 1480 1405


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D.3 Implementation of Single-Phase Auto-Reclosure (SPAR) scheme forTransmission Lines

The OCC Sub-committee reviewed the issue pertaining to SPAR and the status as

indicated during the 80thOCC meeting are given below:

SN Name of the Line OwnershipStatus as given on 80th

OCC meeting.

1 220kV Kopili - Misa # I & II KHEP, NEEPCO Dec, 2012

2 220kV Salakati BTPS - I BTPS, AEGCL Jun, 2013

3 220kV Balipara Samaguri Samaguri, AEGCL Jun, 2013

4 132kV Khandong Haflong KHEP, NEEPCOJun, 2013

5 132kV Khandong Kopili KHEP, NEEPCO


D.4 Agenda by TSECLNEEPCO requested TSECL to provide construction power up to 900 KVA for

combine cycle plant. Accordingly NEEPCO created arrangement by putting 1 No,

6.6/0.4 KV step-down Transformer in their plant. The transformer is charged from

station auxiliary transformer of rating 5 MVA, 132 KV/ 6.6 KV. Therefore, it is

necessary to work out the modalities for metering & billing of quantum of power

selling to NEEPCO by TSECL.

The committee requested TSECL to do the necessary arrangement of metering and

billing for supply of construction power to NEEPCO. TSECL and NEEPCO agreed to

resolve the matter bilaterally.


D.5

Agenda by POWERGRID

1) High Tripping rate & Long Duration Outage of dedicated 11KV Feeder forAuxiliary Power Supply to 132KV Badarpur Substation

The 11 KV HT dedicated feeder emanating from Panchgram Lower Substation

(AEGCL) & connected to 132KV POWERGRID Badarpur Substation was constructed

by ASEB (as a deposit work) for catering to the Auxiliary Power/station load

requirement of 132KV Badarpur Substation.


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However, service of the said feeder has been found to be considerably unreliable.

On an average, the feeder has been found to trip 10-15 times a day with cumulative

outage hours up to 5hrs per day. The matter has been taken up & repeatedly

pursued with ASEB (CAEDCL) on a number of occasions but there has been no

improvement in reliability of the feeder.

The 132KV Badarpur Substation is a vital node for catering to the power

requirement of the 132KV pocket & is connected to major substations viz. 400KV

Silchar Substation & 132KV Panchgram Substation (AEGCL) in addition to 3 other

key substations. Further, the station is playing a significant role for evacuation of

power from Pallatana GBPP to the rest of the 132KV pocket. Hence uninterrupted

auxiliary power supply to the station is of utmost requirement for maintaining a

healthy Protection & Communication System at the station.

ASEB (CAEDCL) may kindly treat the above-said issue with priority & take

necessary action for ensuring uninterrupted power supply through the 11 kV

dedicated feeder connected to POWERGRID Badarpur Substation.

Assam representatives informed that there is some temporary tapping from the 11

kV feeder connected to POWERGRID and necessary action will be taken to resolve

the issue at the earliest.


2) Loadability Enhancement of 132KV Transmission linesNERLDC has requested POWERGRID, vide their letter No.NERLDC/GM/547 dtd

14.11.2012 for enhancement of loading capacity of the following lines:

a) 132KV S/c Badarpur-Khliehriat Lineb) 132KV S/c Loktak-Jiribam-II Linec) 132KV S/c Dimapur-Imphal Lined) 132KV S/c Imphal-Loktak-II Line

NERLDC has stated that enhancement of loading capacity of the above lines is

required for higher load dispatch, particularly in the context of evacuation of power

from Pallatana GBPP.


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Accordingly, POWERGRID has already taken the following actions for increased

loadability:

Upgradation of existing CTs

Upgradation of the terminal CTs of 132KV S/C Loktak-Jiribam_II line, 132KV S/c

Dimapur-Imphal line is being taken up by POWERGRID for which the required

number of CTs of higher capacity (600/1) had already been ordered by

POWERGRID & subsequently dispatched from the manufacturer premises in the

month of July-12. However, 10Nos. CTs were damaged during transit. The matter

has been taken up with the concerned manufacturer for replenishment of the

damaged CTs. The new CTs expected to arrive at site by January13.

Installation of the same shall be carried out on arrival of the new CTs. As for 132KV

Badarpur-Khliehriat line, the terminal CTs installed are of 600/1 capacity.

Further, NERLDC requested to include following lines for enhancement of loading

capacity:

i) 132 kV Khandong- Khlerehiet Iii) 132 kV Khandong - Haflong

Th e comm i t t ee r eques t ed POWERGRID t o com p l et e t h e CT r ep l acemen t o f t h e

abo ve l i n es a t t h e ea r l i es t t o i n c r e a s e t h e l o ad ab i l i t y o f t h e s e l i n e s.

Fixing of Additional Jumpers:

Fixing of additional jumpers at Tension Locations of 132KV Dimapur-Imphal line

has been completed while that for 132KV Jiribam-Loktak_II line is planned for

execution in the month of January-13.

In addition to the above, additional jumpering is now planned to be taken up for

132KV Loktak-Imphal-II & Badarpur-Khliehriat lines in line with NERLDCs

observation.


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The required Special Connectors/Clamps for the purpose are under procurement by

POWERGRID. A tentative schedule for execution of Additional Jumpering Works in

the subject lines is appended below:

Sl.No.

Name of Line No. of TensionLocations for

Additional Jumpering

Proposed schedule

1 132KV Loktak-Imphal- II

38 Loc. 10thFebruary13 to20thFeb13

2 132KV Badarpur-Khliehriat

176 Loc. 25thFeb13 to 10thMar13

POWERGRID shall accordingly propose for the required daytime shutdown of the

respective lines in the preceding OCC Meetings

Constituents agreed to support POWERGRID for carrying out the modification

required for the lines. The committee requested POWERGRID to plan for additional

jumpering.


D.6 Lines under long outagesThe following lines are under long outages

(a)220kV BTPS Agia (one ckt) since Novemeber, 1997(b)132kV Mariani Mokokchung since April, 2008.(c)39km of 132kV Rengpang Jirbam since October, 2002Assam representatives informed about 220 kV BTPS-Agia- II that it is under

stringing stage and it was delayed as the tender was terminated because

contractor cannot complete the said job in time. The new tendering is in progress

and it will be completed at the earliest. Regarding Mariani-Mokokchung line theAssam side is ready; the Nagaland side is required to be checked.

Regarding 132 kV rengpang-Jiribam line the Manipur representatives informed

that the work is in progress and the same will be completed by January, 2013.

Further, NERLDC informed that the Dimapur-Dimapur-II is also under long

outage.


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SE (O), NERPC informed that the shutdown proposals from the next meeting will

be planned one month in advance to co-ordinate with the other region as the OCC

meetings of other regions are held on different dates.


D.10 Estimated Transmission Availability Certificate (TAC) for the month ofNovember, 2012.

The Estimated Transmission/System Availability for the month of October, 2012

furnished by PGCIL is 99.9214% as per details at Annexure D.10. NER

constituents were requested to give their comments and observations, if any, by

30thDecember, 2012 so that Final TAC for the month of November, 2012 can be

issued.


D.11 Major grid disturbances in the previous month (November, 2012 )As intimated by NERLDC, there was no major grid disturbance during the month

of November, 2012.


D.12 Additional Agenda1) F requen t t r i p p i ng o f AGBPP Gas Com pr esso r s : AGBPP Gas Compressors tripped

frequently last one week details attached at Annexure D.12.1. These tripping cause

serious security problem in NER grid during this lean hydro period.

NEEPCO representative informed that there was some problem in compressors and

the same has been rectified.


2) Over d r aw a l b y Cons t i t u e n t s :Due to over drawal by the constituents during peakhours and morning hours many times inter regional import ATC/TTC violation are

observed. This is matter of serious concern for safe, secure and reliable operation of

grid.


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6) Revi ew o n a c t i o n t a k en o n r e comm end a t i o n s o f En q u i r y c omm i t t ee on g r i dd i s t u r b a n c e d t 3 0 . 0 7 .1 2 & 3 1 . 0 7 .1 2 : Action taken by constituents on

recommendations of Enquiry committee on grid disturbance dt 30.07.12 &

31.07.12 is required to be reviewed for proper implementation of recommendation

by the committee to avoid grid disturbance in future.

Th e Comm i t t ee r eq u es t ed a l l u t i l i t y t o i m p l emen t t h e r e comm end a t i o n s o f

E nqu i r y Comm i t t e e.

7) OTPC Per f o rm an ce :

1.On 08.11.12 generation schedule was given for 08.11.12 & 09.11.12.At 2313 Hrs of 08.11.12 GTG-I Synchronised with 15 MW generation .Max

generation was 30 MW. At 0032 Hrs of 09.11.12 GTG-I desynchronised due to

fuel gas line filter differential pressure problem.

2.On 09.11.12 OTPC requested for synchronisation of GTG-I around 15:00 hrs of09.11.2012.

At 1742 Hrs GTG-I synchronised, Max generation was 100 MW & on 10.11.12, At

2148 Hrs GTG-I desynchronised due to feed water system problem.

3.On 09.11.12 generation schedule was given for 12.11.12 & 13.11.12.4.On 09.11.12, revised generation schedule for 09.11.12 & 10.11.12 was given by

OTPC.

On 09.11.12 At 1742 Hrs GTG-I synchronised, Max gen was 100 MW & At 2148

Hrs of 10.11.12, GTG-I desynchronised due to feed water system problem.

5.On 18.11.12, Generation schedule was given for 19.11.12 and 20.11.12.6.On 20.11.12, OTPC Generation schedule was given for 20.11.12 & 21.11.12

At 1626 Hrs, GTG-I Synchronised.Max gen- 160MW

At 1450 Hrs of 21.11.12 GTG-I tripped due to gas booster tripping.

7.On 21.11.12, Generation schedule was given for 21.11.12 and 22.11.12.8.On 22.11.12, Generation schedule was given for 23.11.12 and 24.11.12.


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9.On 23.11.12 revised Generation schedule was given for 23.11.12 and 24.11.12.At 2312 Hrs of 23.11.12 Block-I synchronised but tripped at 2325 Hrs.

On 24.11.12, at 0101 Hrs STG-I Synchronised & at 0130 Hrs GTG-I

Synchronised

On 24.11.12, at 08:48 hrs Block-1 tripped on HP drum level low

10. On 29.11.12 Generation schedule was given for 01.12.12 & 02.12.1211. On 30.11.12 revised Generation schedule was given for 01.12.12 & 02.12.12GTG I Synchronised at 2033 Hrs & STG-I synchronized at 2020 Hrs of 01.12.12

This was discussed under Item No. C.3.

8) With reference to 78thOCC meeting minutes, it was decided that OTPC will give theirgeneration schedule to NERLDC with a copy to NERPC two day in advance, but from

above sequence of events it seems OTPC had never given two days advance

intimation to NERLDC. However, NERLDC always agreed to their generation

schedule and allowed then to generate as per their requirement with the kind

cooperation of the constituents. In this connection message dt 01.12.2012 TSECL

requested for 72 Hours advance intimation before synchronization of OTPC units

along with schedule for maximization of generation, so that they can tie up with

ONGC/GAIL for regulation of their gas supply as per requirement of generation

backing down for accommodating Palatana generation.

This was discussed under Item No. C.3.

D.13 Date & Venue of next OCC meetingIt is proposed to hold the 81st OCC meeting of NERPC on 10th January, 2012

(Thursday). As per roster, Mizoram is the host for 81stOCC meeting. The exact date

and venue will be intimated accordingly.

The meeting ended with thanks to the Chair.

*************


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Annexure-I

List of Participants in the 80thOCC meeting held on 10/12/2012

SN Name & Designation Organization Contact No.

1. Hege Mima, EE Ar. Pradesh 09436041594

2. N.C. Das, CGM Assam 09435559447

3. Sh. B.C. Bordoloi, DGM, SLDC Assam 09435045675

4. Sh. P. C. Sarma, DGM, APGCL Assam 09435119215

5. Sh. G.K. Bhuyan, AGM Assam 09854015601

6. Sh. J. K. Baishya, AGM, SLDC Assam 09435041494

7. Sh. A. K. Saikia, AGM Assam 09864116176

8. Sh. N. Jasobanta Singh, AE Manipur 09612255562

9. Sh. Satyabrata, AE Manipur 09436290565

10. Sh. F.e. Kharshiing, EE, SLDC Meghalaya 03642550020

11. No Representative Mizoram

12. No Representative Nagaland

13. Sh. Bikram Debbarma, DGM, SO Tripura 09436450501

14. Sh. Soumitra Ghosh, Manager Tripura 09862764823

15. Sh. N.R.Paul, DGM NERLDC 09436302723

16. Sh. Anupam Kumar, Engineer. NERLDC 09436335379

17. Sh. P. Kanungo, DGM NERTS 09436302823

18. Sh. B. Goswami, Sr. Mgr. (E) NEEPCO 09436163983

19. Sh. Tanya Taji (E) NEEPCO 09436042053

20. Sh. Surajmani Singh, Mgr.(E) NHPC 09436894857

21. Sh. Mukul Banerjee, GM (Plant) OTPC 08413990766

22. Sh. S.K. Ray Mohapatra, MS I/C NERPC 09818527857

23. Sh.B. Lyngkhoi, SE (O) NERPC 09436163419

24. Sh. D.K. Bauri, EE NERPC 09863317236

80th OCC Minutes Final

Documents

Transcript of 80th OCC Minutes Final