REVISION OF SCHEDULES/REQUISITIONS

A) OUTAGE OF GENERATING UNITB) REVISED DECLARATION OF AVAILABILITY BY CGSC) 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 CGS

SEB’S OPTIONS TO EVENTS

1. PROSPECTIVE REVISION OF CGS AVAILABILITY (UPWARD/DOWNWARD)• SCHEDULE REVISED FOR REMAINING PART OF THE DAY2. TRIPPING OF A CGS 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 CGS 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 CGS REQUISITION, IN CASE FULL ENTITLEMENT WAS

NOT REQUISITIONED EARLIER(IV) ENTER INTO A BILATERAL WITH OTHER SEB/CGS 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 CGS REQUISITION (IF UI RATE FALLS BELOW CGS 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 CGS 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 CGS 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 CGS REQUISITION TO FULL ENTITLEMENT (IF NOT

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

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 CGS 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 SEB

A) 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