REVISION OF SCHEDULES/REQUISITIONS

A) OUTAGE OF GENERATING UNITB) REVISED DECLARATION OF AVAILABILITY BY ISGSC) OUTAGE OF A TRANSMISSION ELEMENTD) UNFORESEEN LOAD-CREASH

TAKES EFFECT FROM

A) 4TH TIME BLOCK IN CASE OF- FORCED OUTAGE OF A GENERATING UNIT- TRANSMISSION CONSTRAINT- GRID DISTURBANCE- SUO MOTO BY RLDC

B) 6TH TIME BLOCK IN CASE OF- REVISION OF DECLARED AVAILABILITY BY ISGS

WHAT ALL CAN HAPPEN?

What all can happen on the day of Operation?

Prospective revision (upward / downward) of ISGS

availability (advised by ISGS through RLDC)

Schedules revision for remaining part of the day

TRIPPING OF ISGS UNIT

TRIPPING OF THE SEB’S UNITS

LOAD CRASH IN THE STATE

FREQUENCY IS GOOD OR HIGHFREQUENCY IS GOOD OR HIGH THE STATE IS OVERDRAWING

THE STATE IS UNDERDRAWINGTHE ISGS IS OVER GENERATINGTHE ISGS IS UNDER GENERATING

FREQUENCY IS LOWFREQUENCY IS LOW

THE STATE IS OVERDRAWING

THE STATE IS UNDER-DRAWING

THE ISGS IS UNDER GENERATING

THE ISGS IS OVER GENERATING

What all can happen on the day of Operation?What all can happen on the day of Operation?

What all can happen on the day of Operation?

TRIPPING OF ISGS UNIT (Known after the event)

Immediate frequency dip

All operating units pick up extra MW, SEB’s drawal reduces

SEBs get UI payment

After the transients : An SEB has the option of adjusting his

generation/load to increase/decrease his net drawal to forgo or

take advantage of UI, till ISGS revises availability and new

schedules come into effect.

What all can happen on the day of Operation? TRIPPING OF THE SEB’S OWN GENERATING UNITS

SEB’s net drawal from the grid increases

SEB has to pay UI

OPTIONSOPTIONS

1. Continue to overdraw and pay UI2. Carry out corresponding load shedding3. Run up all available generation4. Increase ISGS requisition, in case it was not fully requisitioned earlier

5. Enter into a bilateral with another SEB/ISGS for any idling capacity

What all can happen on the day of Operation?

LOAD CRASH IN THE STATE

Under-drawal from the grid and frequency rise

UI implicationsOPTIONSOPTIONS

1. Reduce own generation

2. Reduce ISGS requisition (only if frequency rises/is likely to rise so much that UI price falls below ISGS energy rate

3.Continue to under-draw, in effect supplying UI to the grid. This is advantageous as long as the frequency remains below about 50.2 Hz.

FREQUENCY IS GOOD OR HIGH AND THE STATE IS OVERDRAWING

No problem and no action required

Enhance optimisation, however to the extent possible

1. Reduce own generation to the extent possible, if frequency is above 49.8Hz and increase over-drawal

2. Restore consumer load that had been shed, provided tariff /realisation rate is higher than current UI rate. ( This is also increses overdrawal)

3. Increase ISGS requisition if some part of the entitlement had not been requisition earlier, provided the frequency is ( and is likely to remain) below 50.2Hz. (This would increase the drawal schedule and thereby reduce overdrawal)

FREQUENCY IS GOOD OR HIGH AND THE STATE IS UNDERDRAWING

Action required

1. Reduce own generation to the extent possible, if the frequency is above abiut 49.8 Hz(This would reduce under drawal)

2. Restore consumer load that had been shed, and reduce underdrawal

3. Reduce ISGS requisition, provided the previous two actions have been taken and the frequency continues to be above 50.2 – 50.3 Hz. If frequency is likely to remain below 50.2 Hz, bilateral sell to a needy neighbour can be tried.

FREQUENCY IS LOW AND THE STATE IS OVERDRAWING

Action required

1. Increase own generation to the maximum possible extent

2. Curtail customer load. Load shedding to be graded balancing between UI price and consumer category.

3. Increase ISGS requisition to full entitlement (If not requisitioned fully earlier), and arrange for bilateral purchase from another SEB/ ISGS

FREQUENCY IS LOW AND THE STATE IS UNDER-DRAWING

1. Increase own generation to the extent possible, provided the frequency is below about 49.5 Hz (Comparing variable cost with current UI price)

As such no action required. However the following can be done for enhanced optimisation

2. Curtail consumer load, by shedding low priority load (provided UI earning for the SEB justifies such load shedding). This is totally optional, and helps the grid.

3. Increase ISGS requisition to full entitlement (if not requisitioned fully earlier) and earn UI. Alternately sell the surplus through a bilateral agreement.

OPTIONS OF ISGS TO EVENTSWHAT ALL CAN HAPPEN ON THE DAY OF OPERATION ?

1. PROSPECTIVE REVISION OF DRAWAL REQUISITION BY A BENEFICIARY ( UPWARD / DOWNWARD)

• SCHEDULE REVISED FOR REMAIING PART OF THE DAY BY RLDC

2. TRIPPING OF A GENERATING UNIT OF A STATE (KNOWN AFTER THE EVENT).

• IMMEDIATE FREQUENCY DIP

• ALL OPERATING UNITS PICK UP EXTRA MW,

• ALL STATIONS INJECTION INCREASES

 ISGS RECEVIES UI PAYMENT

OPTIONS OF ISGS :i. GENERATE AS PER SCH. AND FOREGO ADVANTAGE OF UI

ii. INCREASE NET INJECTION BY

• INCREAING OWN GENERATION

RECEIVE UI PAYMENT TILL THE BENEFICIARIES REVISE THEIR REQUISITIONS AND NEW SCHEDULES COME INTO EFFECT OR REDUCE THEIR DRAWALS

3. TRIPPING OF THE OWN GENERATING UNIT OF ISGS

• NET INJECTION OF ISGS REDUCES

STATION HAS TO PAY UI.

 OPTIONS OF ISGS :

i.  CONTINUE TO UNDER GENERATE AND PAY UI.

ii.  INCREASE NET INJECTION BY

 RUNNING UP ALL AVAILABLE GENERATION.Contd….

MINIMISE UI PAYMENT

 iii) REVISE AVAILABILITY DECLARATION WHILE CONTINUING TO UNDER GENERATE (AND PAY UI) TILL REVISED SCHEDULES TAKE EFFECT.

 

iv) ENTER INTO A BILATERAL AGREEMENT WITH OTHER SEB/ISGS TO SUPPLY ANY SURPLUS/ IDLING CAPACITY.

4. LOAD CRASH IN A STATE:

 

• FREQUENCY INCREASES

• ISGS INJECTION REDUCES

UI IMPLICATION (NET GAIN/LOSS).

OPTIONS OF ISGS :

(i) REDUCE INJECTION BY

• REDUCING OWN GENERATION. (IF SYSTEM FREQUENCY IS HIGHER THAN THE STATIONS THRESHOLD FREQUENCY)

  CONTINUE TO UNDER-INJECT, IN EFFECT SUPPLYING UI TO THE GRID. THIS IS ADVANTAGEOUS AS LONG AS THE SYSTEM FREQUENCY IS HIGHER THAN THE STATION’S THRESHOLD FREQUENCY

 (ii) CONTINUE TO GENERATE AS PER SCHEDULE THUS AVOID ANY UI IMPLICATION TILL THE BENEFICIARIES REVISE THEIR REQUISITION AND REVISED SCHEDULES ARE ISSUED BY RLDC.

 (iii) ENTER INTO A BILATERAL AGREEMENT WITH OTHER SEB/REGION TO SUPPLY SURPLUS /IDLING CAPACITY

FREQUENCY IS GOOD OR HIGH

THE ISGS IS OVER GENERATING

THE ISGS IS UNDER GENERATING

FREQUENCY IS LOW

THE ISGS IS UNDER GENERATING

THE ISGS IS OVER GENERATING

What all can happen on the day of Operation?What all can happen on the day of Operation?

FOUR SCENARIOS

A) FREQUENCY IS GOOD OR HIGH, AND THE ISGS IS UNDER GENERATING

 OPTIONS OF ISGS:

i) INCREASE GENERATION IF THE SYSTEM FREQUENCY IS BELOW THE STATION’S THRESHOLD FREQUENCY.

 ii) REDUCE OWN GENERATION TO THE EXTENT POSSIBLE AND THUS REDUCES NET INJECTION SO LONG AS FREQUENCY IS ABOVE THE

STATION’S THRESHOLD FREQUENCY.

iii) GENERATE AS PER SCHEDULE (NO UI IMPLICATION)

FOUR SCENARIOS

B. FREQUENCY IS GOOD OR HIGH, AND THE ISGS IS OVER GENERATING

 OPTIONS OF ISGS :

i) REDUCE OWN GENERATION TO THE EXTENT POSSIBLE, IF THE FREQUENCY IS ABOVE THE STATIONS THRESHOLD FREQUENCY.

ii) INCREASE GENERATION IF FREQUENCY IS BELOW THE STATION’S THRESHOLD FREQUENCY

iii) GENERATE AS PER SCHEDULE (NO UI IMPLICATION)

C) FREQUENCY IS LOW, AND THE STATION IS UNDER GENERATING

OPTIONS OF ISGS :

  i) INCREASE OWN GENERATION TO THE MAXIMUM POSSIBLE EXTENT AS LONG AS THE FREQUENCY IS BELOW THE STATION’S THRESHOLD FREQUENCY (THUS RECEIVE UI).

 ii) GENERATE AS PER SCHEDULE – NO UI IMPLICATION.

FOUR SCENARIOS

 D. FREQUENCY IS LOW, AND THE ISGS IS OVER GENERATING

• NO ACTION REQUIRED

FOLLOWING CAN BE DONE FOR ENHANCED OPTIMIZATION.

 1. INCREASE OWN GENERATION TO THE EXTENT POSSIBLE, PROVIDED THE FREQUENCY IS BELOW THE STATION’S

THRESHOLD FREQUENCY. (THUS RECEIVE UI)

 2. GENERATE AS PER SCHEDULE – NO UI IMPLICATION.

 ACTION DEPENDS ON PREVAILING FREQUENCY, THE STATION’S THRESHOLD FREQUENCY AND IS INDEPENDENT OF WHETHER OVER-GENERATING OR UNDER-GENERATING. IT FOLLOWS THAT ON-LINE MEASUREMENT AND DISPLAY OF TELEMETERED DATA IS NOT ALL THAT CRITICAL

UNSCHEDULED INTERCHANGES (UI)UNSCHEDULED INTERCHANGES (UI)

i.e. deviation from schedules

ENCOURAGE if good for the grid, DISCOURAGE if bad for the grid but allows because it enables meeting more demand and enhances merit order

Good UI helps in improving frequency, and enables one constituent to help the other (for meeting more consumer demand i.e. reducing load shedding)

UI provide the mechanism for on line displacement of costlier generation by cheaper generation: ULTIMATE OPTIMISATION

ACTION DEPENDS ON PREVAILING

FREQUENCY, AND IS INDEPENDENT

OF WHETHER OVER-DRAWING OR

UNDER-DRAWING. IT FOLLOWS

THAT ON LINE MEASUREMENT AND

DISPLAY OF CORRECT NET DRAWAL

IS NOT ALL THAT CRITICAL.

UI = x – Scheduled Drawal

G L

X

IMPORT

X = L - G

0500

10001500200025003000350040004500500055006000

1 2 3 4 5 6 7 8 910111213141516171819202122232446.50

47.00

47.50

48.00

48.50

49.00

49.50

50.00

50.50AP DRAWAL ON A TYPICAL DAY 12.12.2001

0500

10001500200025003000350040004500500055006000

1 3 5 7 9 11 13 15 17 19 21 2347.50

48.50

49.50

50.50

51.50

52.50AP DRAWAL ON A TYPICAL DAY 12.12.2001

GENERATING STATIONINSTALLED CAPACITY IN

MW

ANDHRA PRADESH's SHARE(%)

PEAK

EX-PP CAPABILITY

ON 12/12/2001PEAK

ANDHRA PRADESH'S

ENTITLEMENT IN MWPEAK

ENERGY CHARGE IN

P/KwhTHRESHOLD FREQ (HZ)

NTPC,RAMAGUNDAM 2100 34.072 1923 655 86.22 50.19NLY-II STG1,NEYVELI 660 19.456 515 100 114.62 50.09NLY-II STG2,NEYVELI 870 25.419 517 131 165.22 49.91

MADRAS ATOMIC POWER STATION 340 9.753 290 28 57.49 50.29

KAIGA ATOMIC POWER STATION 440 31.667 380 120 310 49.39

TOTAL COST ASSUMED AS VARIABLE BECAUSE SINGLE COST SPECIFIED.AP'S OWN GENERATION

VIJ AYAWADA.T.P.S 1260 100 1061 1061 102.8 50.13KOTHAGUDEM T.P.S 670 100 474 474 123.1 50.06

KOTHAGUDEM T.P.S-V 500 100 252 252 102.1 50.14RAYALASEEMA T.P.S 420 100 441 441 124.5 50.06

NELLORE T.P.S 30 100 26 26 233.8 49.67VIZAG STEEL PLANT CAPTIVE 100 60 60 196 49.80

NAVBHARAT CAPTIVE 100 20 20 208 49.76GVK,J EGURUPADU 216 100 210 210 83 50.20

SPECTRUM 208 100 190 190 83 50.20VIJ J ESWARAM GTS-1 100 100 101 101 86 50.19VIJ J ESWARAM GTS-1I 172.5 100 171 171 87 50.19LANCO,KONDAPALLI 350 100 320 320 91.5 50.17

SRISAILAM 770 100 524 524N'SAGAR 810 100 270 270L.SILERU 460 100 300 300U.SILERU 240 100 170 170

TOTAL COST ASSUMED AS VARIABLE BECAUSE SINGLE COST SPECIFIED.*Hydel units are subject to annual schedules.

AVAILABILITY OF ANDHRA PRADESH:-TYPICAL DATA ON 12/12/2001

NIL* NA

SCHEDULING FOR KARNATAKA(ACTUAL) ON 04-01-02

0100200300400500600700800900

10001100120013001400150016001700180019002000210022002300240025002600270028002900300031003200330034003500360037003800390040004100420043004400

1 3 5 7 9 11 13 15 17 19 21 23HOUR

MW

CGS ENTITLEMENTS INCLUDING ER = 854 MW

THERMAL+DIESEL

IPP

HYDRO

DEMAND

24.3 MU

SCHEDULING FOR KARNATAKA (EXPECTED) ON 04-01-02

0100200300400500600700800900100011001200130014001500160017001800190020002100220023002400250026002700280029003000310032003300340035003600370038003900400041004200430044004500460047004800

1 3 5 7 9 11 13 15 17 19 21 23HOUR

MW

CGS ENTITLEMENTS INCLUDING ER = 854 MW

THERMAL+DIESEL

IPP

HYDRO

DEMAND

24.3 MU

GENERATING STATIONINSTALLED CAPACITY

IN MWKARNATAKA'S

SHARE(%)PEAK

EX-PP CAPABILITY

ON 04/01/2002

PEAK

KARNATAKA'S ENTITLEMENT IN

MWPEAK

ENERGY CHARGE IN P/Kwh

THRESHOLD FREQ (HZ)

NTPC,RAMAGUNDAM 2100 19.554 1923 376 37.66 50.37NLY-II STG1,NEYVELI 580 24.649 515 127NLY-II STG2,NEYVELI 790 24.379 512 125

MADRAS ATOMIC POWER STATION 340 7.234 130 9KAIGA ATOMIC POWER STATION 440 28.401 410 116

EASTERN REGION 500 21.2 475 101TOTAL GENERATION 4750 3965 854

AFTER APPORTIONING LOSS OF 2.86% 830KARNATAKA'S OWN GENERATION

RAICHUR THERMAL 1260 100 967 967YELAHANKA DIESEL 128 100 108 108

THERMAL TOTAL 1388 1075 1075SHARAVATHY 1035 100 869 869

LINGANAMAKKI 55 100 20 20GERSOPPA 180 100 0 0NAGJHARI 840 100 520 520

SUPA 100 100 45 45KADRA 150 100 94 94

KODASALLI 120 100 80 80VARAHI 230 100 165 165MANI 9 100 0 0

GHATAPRABHA 32 100 19 19BHADRA 39.2 100 9 9

SHIVA 42 100 0 0SHIMSHA 17.2 100 7 7

MUNIRABAD 27 100 15 15MAHATMA GANDHI 120 100 30 30

HYDRO TOTAL 2996 100 1873 1873

JINDAL IPP 260 100 120 120

THANEERBHAVI NAPTHA 230 100 211 211

TATA DIESEL 81 100 64 64

RAYALASEEMA 27 100 26 26IPP TOTAL 598 421 421

TOTAL GENERATION 4982 3369 3369

AVAILABILITY OF KARNATAKA:-TYPICAL DATA ON 04/01/2002

SCHEDULING FOR KERALA

0100200300400500600700800900

100011001200130014001500160017001800190020002100220023002400

01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24HOURS

MW

NLY-II STG1 57 MWNLY-II STG2 60 MW

ER 74 MW

KAYAMKULAM 150 MW

KAPS 38 MW

NTPC 238 MW

MAPS 7 MW

IPP&DIESEL 119 MW

SCHEDULING FOR KERALA

0100200300400500600700800900

100011001200130014001500160017001800190020002100220023002400

01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24HOURS

MW

KAYAMKULAM 150 MW

IPP&DIESEL 119 MW

CGS ENTITLEMENTS INCL ER 474 MW

HYPOTHETICAL 04.01.2002

GENERATING STATIO N INSTALLED KERALA'S EX-PP KERALA'S ENERGY THRESHOLD NTPC,RAMAGUNDAM 2100 12.112 1923 233 86.22 50.19NLY-II STG1,NEYVELI 660 11.132 515 57 114.62NLY-II STG2,NEYVELI 870 11.651 512 60 165.22

MADRAS ATOMIC POWER STATION 340 5.445 130 7 57.49KAIGA ATOMIC POWER STATION 440 9.187 410 38 310

EASTERN REGION 500 19.6 475 93TO TAL 4910 3965 488

KERALA OWN GENERATIO NKUTTIADI + EXTN 125 100 115 115

SHOLAYAR 54 100 36 36PORINGAL+BANK 48 100 40 40

PALLIVASAL 37.5 100 13 13SENGULAM 48 100 24 24PANNIAR 30 100 16 16

NERIMANGALAM 45 100 45 45SABARIGIRI 300 100 300 300

IDUKKI 780 100 590 590IDAMALAYAR 75 100 35 35

KALLADA 15 100 6 6L.PERIYAR 180 100 146 146KAKKAD 50 100 38 38

MINI HYDRO 26.5 100 13 13HYDRO TO TAL 1814 100 1417 1417

BRAHMAPURAM DIESEL 106.5 100 18 18KOZHIKODE DIESEL 128.8 100 88 88

KAYAMKULAM 350 100 156 156BSES GAS 130.5 100 0 0

KASARGODE POWER 21.93 100 20 20THERMAL TO TAL 738 100 282 282

TO TAL GENERATIO N 2552 100 1700 1700

AVAILABILITY O F KERALA:-TYPICAL DATA O N 04/01/2002

TOTAL COST AS SINGLE COST SPECIFIED.

SCHEDULING FOR TAMILNADU(ACTUAL)

-300-200-1000100200300400500600700800900100011001200130014001500160017001800190020002100220023002400250026002700280029003000310032003300340035003600370038003900400041004200430044004500460047004800490050005100520053005400550056005700580059006000610062006300

1 3 5 7 9 11 13 15 17 19 21 23HOUR

MW

THERMAL+DIESEL+GAS

IPP

HYDRO

DEMAND

CGS ENTITLEMENTS INCLUDING ER:1118 MW

KADAMPARAI IN PUMP MODE

04.01.2002

SCHEDULING FOR TAMILNADU(EXPECTED)

-300-200-100010020030040050060070080090010001100120013001400150016001700180019002000210022002300240025002600270028002900300031003200330034003500360037003800390040004100420043004400450046004700480049005000510052005300540055005600570058005900600061006200630064006500

1 3 5 7 9 11 13 15 17 19 21 23HOUR

MW

THERMAL+DIESEL+GAS

IPP

HYDRO

DEMAND

CGS ENTITLEMENTS INCLUDING ER:1118 MW

KADAMPARAI IN PUMP MODE

04.01.2002

GENERATING STATIONINSTALLED CAPACITY

IN MW

TAMIL NADU'S

SHARE(%)PEAK

EX-PP CAPABILITY

ON 04/01/2002

PEAK

TAMIL NADU'S ENTITLEMENT

IN MWPEAK

ENERGY CHARGE IN P/Kwh

THRESHOLD FREQ (HZ)

NTPC,RAMAGUNDAM 2100 25.506 1923 490 91.48 50.17NLY-II STG1,NEYVELI 580 32.239 515 166NLY-II STG2,NEYVELI 790 35.379 512 181

MADRAS ATOMIC POWER STATION 340 76.058 130 99KAIGA ATOMIC POWER STATION 440 27.719 410 114

EASTERN REGION 500 21.2 475 101TOTAL GENERATION 4750 3965 1151

1118TAMIL NADU'S OWN GENERATION

Ennore TPS 450 100 134 134 203.36 49.77North Chennai TPS 630 100 644 644 142 49.99

Tuticorin TPS 1050 100 870 870 144 49.99Mettur TPS 840 100 850 850 142 49.99Neyveli TS1 600 100 398 398Basin Bridge 120 100 52.4 52.4 489 48.75

Kovil kalappal 105 100 90 90THERMAL+ GAS TOTAL 3795 3038 3038

Pykara 72 100 48.6 48.6Moyar 36 100 22 22

Parsonsvalley 30 100 0 0Kundah - 1 60 100 24 24Kundah - 2 175 100 50 50Kundah - 3 180 100 82 82Kundah - 4 100 100 63 63Kundah - 5 40 100 0 0Kadamparai 400 100 388 388

Aliyar 60 100 58 58Mettur Dam 40 100 10.4 10.4

Mettur Tunnel 200 100 56 56LMHEP-Barrage-1 30 100 15.8 15.8LMHEP-Barrage-2 30 100 15 15LMHEP-Barrage-3 30 100 15 15LMHEP-Barrage-4 30 100 12.6 12.6

Periyar 140 100 58 58Servalar 20 100 16.8 16.8

Papanasam 28 100 20.2 20.2Sarkarpathy 30 100 27.2 27.2Sholayar-1 70 100 31.2 31.2Sholayar-2 25 100 0 0Kodayar-1 60 100 60 60Kodayar-2 40 100 40 40

HYDRO TOTAL 1926 100 1114 1114Pillai Perumal Nallur 331 100 0 0 282 49.49

Samalpatty 105 100 101.2 101.2 225 49.70TCPL 63.5 100 57.6 57.6

Madurai PCL 106 100 105.5 105.5 214 49.74GMR PCL 196 100 186 186 212 49.74IPP TOTAL 802 450 450

TOTAL GENERATION 6523 4603 4603

AVAILABILITY OF TAMIL NADU:-TYPICAL DATA ON 04/01/2002

AFTER APPORTIONING LOSS OF 2.86%

FEATURES OF SPECIAL ENERGY METERS :• ACCURACY : 0.2 S AS PER OEC -687, 1992

• STATIC, TOTALLY TAMPER - PROOF, SEALED FOR LIFE

• GALVANIC ISLATION AND SURGE SUPRESSION

• TWO STANDARD MODELS : 110V, 1A AND 110V, 5A

• NON - VOLATILE MEMORY FOR 10 DAYS

• HARMONICS FILTERED OUT AND ONLY FUNDAMENTAL ENERGY RECORDED

• ALL MEASUREMENTS, RECORIDNG IN SECONDARY QUANTITIES. CT AND VCT RATION APPLIED IN REGIONAL COMPUTATION

• NET ENERGY ( WH) EXCHANGE IN EACH 15 MIN. BLOCK

• CUMULATIVE WH TRANSMITTAL AT EACH MIDNIGHT

• AVERAGE FREQUENCY IN EACH 15 MIN. BLOCK

• CUMULATIVE REACTIVE ENERGY EXCHANGE WHILE VOLTAGE IS 97% OR BELOW

• CUMULATIVE REACTIVE EXCHANGE WHILE VOLTAGE IS 103% OR ABOVE.

• HIGH-ACCURACY OF INTERNAL CLOCK: ONE MINUTE/MONTH,WITH RESTRICTED ADVANCE/ RETARD FACILITY

• TAGGING OF DATA WITH DATE, TIME METER NO. IDENTIFICATION OF TIME BLOCK WHEN VT SUPPLY DISTRUBED

• NO SEPARATE AUXILIARY SUPPLY ; ONLY OPTICAL COUPLER FOR DATA COLLECTION ( WEEKLY)

• DISPLAYS TO APPRISE THE SUBSTATION OPERATOR AS TO WHAT IS BEING RECORDED IN METERS MEMORY

SEB’S OPTIONS TO EVENTS

1. PROSPECTIVE REVISION OF ISGS AVAILABILITY (UPWARD/DOWNWARD)• SCHEDULE REVISED FOR REMAINING PART OF THE DAY2. TRIPPING OF A ISGS UNIT (KNOWN AFTER THE EVENT)• IMMEDIATE FREQUENCY DIP• ALL OPERATING UNITS PICK UP EXTRA MW• SEB’S DRAWAL REDUCES SEB RECEIVES UI PAYMENT SEB’S OPTIONS:(I) DRAW AS PER SCHEDULE AND FOREGO ADVANTAGE OF UI(II) REDUCE NET DRAWAL BY• INCREASING OWN GENERATION AND/OR REDUCING LOAD> RECEIVE UI PAYMENT TILL ISGS REVISES ITS AVAILABILITY AND NEW

SCHEDULES COME INTO EFFECT

3. TRIPPING OF THE SEB’S OWN GENERATING UNIT

• SEB’S NET DRAWAL INCREASES SEB HAS TO PAY UI SEB’S OPTIONS(I) CONTINUE TO OVERDRAW AND PAY UI(II) REDUCE NET DRAWAL BY• CARRYING OUT CORRESPONDING LOAD SHEDDING AND/OR RUN UP ALL AVAILABLE GENERATION(III) INCREASE ISGS REQUISITION, IN CASE FULL ENTITLEMENT WAS

NOT REQUISITIONED EARLIER(IV) ENTER INTO A BILATERAL WITH OTHER SEB/ISGS TO DRAW ANY

SURPLUS/IDLING CAPACITY

4. LOAD CRASH IN THE STATE:• FREQUENCY INCREASES• UNDER DRAWAL FROM THE GRID UI IMPLICATION (NET GAIN/LOSS)

SEB’S OPTIONS:(I) INCREASE DRAWAL BY• REDUCING OWN GENERATION (IF UI RATE IS LOWER THAN THE

RESPECTIVE ENERGY RATE)• RESTORE DISCONNECTED LOADS (IF UI RATE IS LOWER THAN THE

RECOVERY RATE)• REDUCE ISGS REQUISITION (IF UI RATE FALLS BELOW ISGS ENERGY

RATE)CONTINUE TO UNDER DRAW, IN EFFECT SUPPLYING UI TO THE GRID. THIS IS

ADVANTAGEOUS AS LONG AS THE UI RATE IS HIGHER THAN THE ENERGY RATE

FOUR SCENARIOS …1

A. FREQUENCY IS GOOD OR HIGH, AND THE STATE IS OVERDRAWING:- NO PROBLEM, AND NO ACTION REQUIRED

FOR ENHANCED OPTIMIZATION, HOWEVER TO THE EXTENT POSSIBLE.(I) REDUCE OWN GENERATION TO THE EXTENT POSSIBLE AND INCREASE

OVERDRAWAL SO LONG AS FREQUENCY IS ABOVE ABOUT 49.8 HZ.(II) RESTORE CONSUMER LOAD THAT HAD BEEN SHED, PROVIDED

TARIFF/REALIZATION RATE IS HIGHER THAN CURRENT UI RATE. (THIS ALSO INCREASES OVERDRAWAL)

(III) INCREASE ISGS REQUISITION, IF SOME PART OF THE ENTITLEMENTS HAD NOT BEEN REQUISITIONED EARLIER, PROVIDED THE FREQUENCY IS (AND IS LIKELY TO REMAIN) BELOW ABOUT 50.2 Hz. (THIS WOULD INCREASE THE DRAWAL SCHEDULE AND THEREBY REDUCE OVERDRAWAL)

FOUR SCENARIOS …2B. FREQUENCY IS GOOD OR HIGH, AND THE STATE IS UNDER DRAWING: ACTION

REQUIRED(I) REDUCE OWN GENERATION TO THE EXTENT POSSIBLE, IF THE

FREQUENCY IS ABOVE ABOUT 49.8 HZ. (THIS WOULD REDUCE UNDERDRAWAL)

(II) RESTORE CONSUMER LOAD THAT HAD BEEN SHED, AND REDUCE UNDERDRAWAL

(III) REDUCE ISGS REQUISITION, PROVIDED THE PREVIOUS TWO ACTIONS HAVE BEEN TAKEN AND THE FREQUENCY CONTINUES TO BE ABOVE 50.2-50.3 HZ. IF FREQUENCY IS LIKELY TO REMAIN ABOVE 50.2 HZ., BILATERAL SALE TO A NEEDY NEIGHBOUR CAN BE TRIED

C. FREQUENCY IS LOW, AND THE STATE IS OVERDRAWING: ACTION REQUIRED(I) INCREASE OWN GENERATION TO THE MAXIMUM POSSIBLE EXTENT(II) CURTAIL CONSUMER LOAD, LOAD SHEDDING TO BE GRADED

BALANCING BETWEEN UI PRICE AND CONSUMER CATEGORY(III) INCREASE ISGS REQUISITION TO FULL ENTITLEMENT (IF NOT

REQUISITIONED FULLY EARLIER), AND ARRANGE FOR BILATERAL PURCHASE FROM ANOTHER SEB/ISGS

FOUR SCENARIOS …3D. FREQUENCY IS LOW, AND THE STATE IS UNDERDRAWING: NO ACTION

REQUIRED; FOLLOWING CAN BE DONE FOR ENHANCED OPTIMIZATION.

(I) INCREASE OWN GENERATION TO THE EXTENT POSSIBLE, PROVIDED THE FREQUENCY IS BELOW ABOUT 49.5 HZ. (COMPARING VARIABLE COST WITH CURRENT UI PRICE)

(II) CURTAIL CONSUMER LOAD,BY SHEDDING LOW PRIORITY LOAD (PROVIDED UI EARNING FOR THE SEB JUSTIFIES SUCH LOAD SHEDDING). THIS IS TOTALLY OPTIONAL, AND HELPS THE GRID

(III) INCREASE ISGS REQUISITION TO FULL ENTITLEMENT (IF NOT REQUISITIONED) FULLY EARLIER), AND EARN UI OR SELL THE SURPLUS THROUGH A BILATERAL AGREEMENT

ACTION DEPENDS ON PREVAILING FREQUENCY, AND IS INDEPENDENT OF SHETHER OVERDRAWING OR UNDERDRAWING. IT FOLLOWS THAT ON-LINE MEASUREMENT AND DISPLAY OF CORRECT NET DRAWAL IS NOT ALL THAT CRITICAL.

MANAGEMENT OF DRAWALS

CURTAILMENT OF DRAWAL BY SEBA) IF UI RATE IS HIGHER THAN THE HIGHEST

ENERGY RATE OF THE STATIONS SCHEDULED, THEN CURTAIL DRAWAL BY MAXIMISING CHEAPER GENERATION

B) IF UI RATE IS HIGHER THAN CONSUMER LOAD NET RECOVERY RATE THEN CURTAIL DRAWAL BY LOAD SHEDDING