AVAILABILITY BASED TARIFF SCHEDLING PROCEEDURE AND SETTLEMENT MECHANISM UNDER ABT REGIME T. SRINIVAS MANAGER,SRLDCBANGALORE

LINKS GIST OF CGS BRIEF OF ABT SCHEDULING PROCEDURE SETTLEMENT SYSTEM UI

SOUTHERN REGIONAL GRID ▀ Central Generating Stations in the Region are Ramagundam Super Thermal Power Stn. : 2,600 MW (200x x4) Neyveli Lignite Corporation Ltd. - II : 1,470 MW (210 x 7) Madras Atomic Power Station : 390 MW (170 x X1) Kaiga Atomic Power Station : 440 MW (220x2) NLC EXPANSION TPS 1 : 420 MW (210X2) TALCHER STAGE II : 2000 MW (500X4) situated in ER ▀ Beneficiaries in southern Region are. ANDHRA PRADESH KARNATAKA KERALA TAMIL NADU Union Territory of Pondicherry NLCMINES GOA has share of 100MW from RSTPS

CONTROL AREAS REGIONAL GRID SEB’S GRID CS -3 CS - 2 CS - 1 CENTRAL SHARE STATE GENR STATE IPP DISTR -B DISTR - A DISTR - C SEB - A SEB -CSEB -B SLDC COORDINATES DIRECTS RLDC COORDINATES

KHAMMAM VIJAYAWADA NAGARJUNASAGAR VISAKHAPATNAM (POWERGRID) HYDERABAD RAICHUR GOOTY HOODY SALEM UDUMALPET TRICHUR MADURAI TRICHY MADRAS NEYVELI CUDDAPAH DAVANAGERE KAIGA RSTPP 130x2 164x x2 PONDICHERY BANGALORE SIRSI MUNIRABAD P P P P P P P P P P P P P P P N KOLAR PALLOM KAYANKULAM EDAMON JEYPORE x78 2x HOSUR KADRA KODASAALY Nagjhari MAPS P SSLMM MMDP THIRUVANATHAPURAM ALMATHI NELLORE 400 KV LINE PRESENTLY OPERATED AT 220 KV NELAMANGALA KURNOOL GAZUWAKA(AP) SIMHADRI NTPC HIRIYUR x x2 221x2 146x2 52x2 197x2 301x2 8x4 15x TALGUPPA AC TRANSMISSION NETWORK IN SR KOODANKULAM THIRNELVALI

GENERATORS ABOVE 1000 MW GENERATORS 500 – 1000 MW GENERATORS BELOW 500 MW - HYDRO - THERMAL - GAS / NAPTHA - NUCLEAR LOAD MW LOAD MW MAJOR GENERATORS SCATTERED ACROSS SR MAJOR LOAD CENTRES SCATTERED ACROSS SR KOLAR FROM TALCHER (4 x 500MW) ±500KV KUDAKULAM APP 2 x 1000MW BACK

CONVENTIONAL METHOD OF OPERATION SHARE BASED ON ACTUAL GENERATION:- SHARE BASED ON ACTUAL GENERATION:- DOES NOT REFLECT THE AVAILABILITY OF ISGS –RATHER ITS EX-BUS GENERATION DOES NOT REFLECT THE AVAILABILITY OF ISGS –RATHER ITS EX-BUS GENERATION IS FIXED AND TIME INVARIANT IS FIXED AND TIME INVARIANT INSENSITIVE TO CONSTRAINTS INSENSITIVE TO CONSTRAINTS DOES NOT ALLOW FOCUSED CHANGES DOES NOT ALLOW FOCUSED CHANGES SUB OPTIMAL UTILIZATION OF RESOURCES SUB OPTIMAL UTILIZATION OF RESOURCES

CONVENTIONAL METHOD OF ENERGY ACCOUNTING PAYMENTS ARE MADE AS PER THE DRAWALS PAYMENTS ARE MADE AS PER THE DRAWALS OVER AND UNDER DRAWALS - UNAVOIDABLE OVER AND UNDER DRAWALS - UNAVOIDABLE UNUTILISED RESOURCES ARE OFTEN BILLED. UNUTILISED RESOURCES ARE OFTEN BILLED. INFLEXIBLE – BILATERALS, SHORT TERM CONTRACTS – NOT ALLOWED INFLEXIBLE – BILATERALS, SHORT TERM CONTRACTS – NOT ALLOWED

ADVANTAGES OF SCHEDULING SCHEDULE REFLECTS BOTH –AVAILABILITY OF ISGS & REQUIREMENT OF CONSTITUENT SCHEDULE REFLECTS BOTH –AVAILABILITY OF ISGS & REQUIREMENT OF CONSTITUENT FLEXIBILITY FLEXIBILITY TIME VARIANT - MIRRORS GRID BEHAVIOUR TIME VARIANT - MIRRORS GRID BEHAVIOUR SENSITIVE TO CONSTRAINTS SENSITIVE TO CONSTRAINTS FOCUSED – SCHEDULE IS NON GENERIC FOCUSED – SCHEDULE IS NON GENERIC OPTIMAL UTILIZATION OF RESOURCES OPTIMAL UTILIZATION OF RESOURCES ECONOMIC OPERATION ECONOMIC OPERATION INDEPENDENT OF SETTLEMENT SYSTEM. INDEPENDENT OF SETTLEMENT SYSTEM.

C H A P T E R - 7 SCHEDULING & DESPATCHING CODE Demarcation of Responsibilities. Each Region is a loose power pool and each state is a notional Control Area. (Decentralized Scheduling and Dispatch). RLDC can direct SLDCs/ISGSs in case of system contingencies, to change drawal/injection and if time permits, RLDC will ascertain whether situation has arisen due to => Deviations from schedule => Bilateral Exchange or Short Term Open Access These can be terminated by RLDC.. All joint/bilateral agreements to be filed with RLDC/REB Secretariat.SEMs to be installed by CTU at all interconnection points for recording Actual Interchanges and MVARh drawals.. Regional Energy Accounting to be done by REB Sectt.based on metered and processed data (Actual net injection of ISGS and actual net drawal of each beneficiary) received from RLDC. SRLDC/Comml/IEGC/33

Settlement Systems*. Accounting on weekly basis. Capacity and Energy Charges billing on monthly basis Billing of adjustments for deviations on weekly basis RLDC to furnish data to REB Secretariat by Thursday noon for week ending Sunday. REB Secretariat to finalize and issue REA by Tuesday, for seven day period ending on penultimate Sunday. All data to be retained for 20 days (for RLDC & REB) for verification. Commercial Mechanism * Availability Based Tariff ( a) Capacity Charge (b) Energy Charge (c) Adjustment for Deviations SRLDC/Comml/IEGC/34

Scheduling Process On Day-l 10 AM ISGSs advise foreseen plant-wise ex-. power plant MW, MWh * capability for next day 11 AM RLDC advises SEBs their MW, MWh* shares in foreseen ISGSs' availability 3 PM 3 PM SLDCs furnish their,time-wise MW requisition from the above, and schedule of bilateral exchanges, if any 5 PM RLDC issues' despatch schedules' for ISGSs and 'net drawal schedules' for SEBs, for each hour the next day starting at midnight 10 PM SLDCs may inform any change of the above or bilateral exchanges to RLDC, if required by any new development during the day 11 PM Schedules frozen for the next day. RLDC Issues final drawal schedules to each State & Despatch schedule to each ISGS SRLDC/Comml/IEGC/41

On Day 0 On Day + 1. RLDC to issue before-the- fact Capacity Declaration/Schedules finally implemented by RLDC (Datum for accounting and working out average ex-power plant capability). Time block t Any State may revise drawal schedule from any/all ISGS Any ISGS may revise their foreseen capability Time block t+3 RLDC to issue revised ‘ drawal schedules' and despatch schedules SRLDC/Comml/IEGC/42

Scheduling Process Scheduling for the next day Every day by 10 AM, RLDC collects the foreseen plant-wise ex-power plant MW capability of ISGSs for the next day By 11 AM, RLDC advises SEBs, on a 15 minutes blockwise level, their entitled MW shares from each ISGSs’ availability By 3 PM, RLDC receives block-wise MW requisition from SLDCs and also the schedule of bilateral exchanges, if any By 5 PM, RLDC issues ‘despatch schedules’ for ISGSs and ‘net drawal schedules’ for SEBs, 15 minutes block-wise for the next day starting at midnight. Upto 10 PM SLDCs may inform any change of the above or bilateral exchanges to RLDC, if required by any new development during the day. At 11 PM Schedules are frozen for the next day. RLDC issues final drawal schedules to each State & Despatch schedule to each ISGS.

Scheduling Process Any change of schedule for the current day In case of any forced outage of a unit, or in case of any transmission bottleneck or in the interest of better system operation, RLDC may revise the schedules. The revised schedules will become effective from the 4 th time block. ISGSs and/or SLDCs may also revise their schedules during a day. The revised schedules will become effective from the 6 th time block.

REVISION OF SCHEDULES/REQUISITIONS A) OUTAGE OF GENERATING UNIT B) REVISED DECLARATION OF AVAILABILITY BY ISGS C) OUTAGE OF A TRANSMISSION ELEMENT D) UNFORESEEN LOAD-CRASH TAKES EFFECT FROM A) 4 TH TIME BLOCK IN CASE OF - FORCED OUTAGE OF A GENERATING UNIT - TRANSMISSION CONSTRAINT - GRID DISTURBANCE - SUO MOTO BY RLDC B) 6 TH TIME BLOCK IN CASE OF - REVISION OF DECLARED AVAILABILITY BY ISGS -REVISION OF REQUISITIONS BY BENEFICIARIES

A new scheduling software in Visual Basic is developed by SRLDC which has the following advantages: - Minimize data entry errors. - Faster reconciliation of schedules - Facilitate electronic data transfer - Modularly structured, simple and practicable

SCHEDULING METHODOLOGY The station-wise (Ex-bus) capability would be submitted by the ISGSs in the specified format. ISGSs would declare the capability i.e. the MW and MWH quantum in the absolute values and not in the form of some relative percentages or in any other manner.

SCHEDULING METHODOLOGY Based on the declared capability & the allocations of different States / Beneficiaries in different ISGSs, the station wise entitlements would be worked out and intimated to all the States/Beneficiaries by SRLDC.

SCHEDULING METHODOLOGY The requisitions would be submitted by the States in the specified format. The States would submit the requisitions indicating the quantum desired against the given entitlement, and not the quantum surrendered. The requisitions in case of nuclear and run of the river hydro stations would be equal to the entitlements.

SCHEDULING METHODOLOGY The details of the despatch and drawal schedules and Unrequisitioned, surpluses shall be made by SRLDC and the information would be exchanged through fax and/or through FTP.

SCHEDULING METHODOLOGY In the event of any unrequisitioned surpluses, the Owner State ( the State to which the share actually belongs and pays the capacity charges) may find out a suitable Buyer/ Willing State to take such unrequisitioned surplus and/or the Buyer/Willing State may contact the Owner State for such exchange. The agreed Short Term Open Access Transactions be intimated / consented to SRLDC by both the States for incorporating in the final schedules.

SCHEDULING METHODOLOGY Any unrequisitioned surpluses still available, can be agreed for Short Term Open Access Transactions between the concerned ISGS and one or more desiring States. The agreed Short Term Open Access Transactions from ISGS to a State be intimated to SRLDC by both the agencies (ISGS as well as States) for incorporation in the final schedule.

SCHEDULING METHODOLOGY During the current day in case the Owner State requisitions back its surrendered share, then the same is withdrawn from the other State/ States to which it was allocated as surplus energy and the schedules are revised in line with the Grid Code.

SCHEDULING METHODOLOGY While making or revising their declaration of capability the generators shall ensure that the declared capability during peak hours is not less than during other hours.

SCHEDULING METHODOLOGY While communicating the requisitions, the States shall ensure that:  maximum economy and efficiency in the operation of the power system in the State is achieved while requisitioning and /or surrendering power from different ISGSs vis-à-vis from their own stations.  the requisitions are operationally reasonable, particularly in terms of ramping-up / ramping-down rates and ratio between minimum and maximum generation levels, and are in line with the agreed philosophy in the region amongst different agencies.

SCHEDULING METHODOLOGY In the event of despatch schedule in respect of a particular ISGS, (as agreed between ISGS and the State constituents in respect of thermal units it would be taken as 70%) the changes in requisition between two successive blocks is higher than a ramp up/down quantum, then the State/States due to which such anomaly is being experienced would be requested by SRLDC to change its/their requisition in that particular ISGS, to make the schedule operationally reasonable.

SCHEDULING METHODOLOGY While issuing the final schedules, SRLDC shall check that the schedules do not give rise to any transmission constraints. In case any imperssible constraints/ anomalies are foreseen, the RLDC shall moderate the schedules to the required extent, under intimation to the concerned agencies.

SCHEDULING METHODOLOGY During the periods of low demand in the region, in spite of all efforts if the despatch schedule of an ISGS(s) during certain blocks in the off-peak period remains below the minimum agreed value, and the concerned ISGS (s) is not able to operate the units due to technical constraints, then the concerned ISGS(s) may close down some unit(s) in consultation with SRLDC and the despatch schedule of the ISGS(s) shall be revised accordingly. Under such a situation the net drawal schedule of the beneficiary (ies) having share in the ISGS(s), may get reduced during peak hours also.

SCHEDULING METHODOLOGY If at any point of time SRLDC observes that there is need for revision of schedules in the interest of better system operation, it may do so on its own and make it effective in line with the grid code provisions.

SCHEDULING METHODOLOGY While entering into a bilateral agreement, the concerned parties shall ensure that the agreements are clear and explicit and contains all the relevant details which may be necessary from scheduling and computation of energy flow. BACK

Payment to Inter State Generating Stations (ISGS) from beneficiaries under Availability Based Tariff (ABT)  Capacity charges  Energy charges  Unscheduled Interchange (UI)

CAPACITY CHARGE Capacity charge will be related to ‘availability’ of the generating station and the percentage capacity allocated to the state. ‘Availability’ for this purpose means the readiness of the generating station to deliver ex-bus output expressed as a percentage of its rated ex-bus output capability.

ENERGY CHARGE Energy charges shall be worked out on the basis of a paise per kwh rate on ex-bus energy scheduled to be sent out from the generating station as per the following formula Energy charges = Rate of energy charges (paise/kwh) x Scheduled Generation (ex-bus MWh)

UNSCHEDULED INTERCHANGE (U I) :  Variation in actual generation / drawal with respect to scheduled generation / drawal shall be accounted for through Unscheduled Interchange (UI).  UI for generating station shall be equal to its total actual generation minus its scheduled generation.  UI for beneficiary shall be equal to its total actual drawal minus its total scheduled drawal.

UNSCHEDULED INTERCHANGE (U I) :  UI shall be worked out for each 15 minute time block.  Charges for all UI transactions shall be based on average frequency of the time block.  UI rates shall be frequency dependent and uniform throughout the country.

UI RATE Rate of Unscheduled Drawal/Injection Frequency (Hz) Rate (p/u) Above and below 570

AVAILABILITY BASED TARIFF (A) CAPACITY CHARGE (B) ENERGY CHARGE (C) ADJUSTMENT FOR DEVIATIONS (U I CHARGE) (U I CHARGE) (A) = a function of the Ex-Bus MW availability of Power Plant for the day declared before the day starts x SEB’s % allocation from the plant (B) = MWh for the day as per Ex-Bus drawal schedule for the SEB finalised before the day starts x Energy charge rate (C) = Σ (Actual energy interchange in a 15 minute time block – scheduled energy interchange for the time block) x UI rate for the time block TOTAL PAYMENT FOR THE DAY = (A) + (B) ± (C)

FEATURES :  ( A) and (B) do not depend on actual plant generation / drawal. No metering required for this as they are based on off-line figures. All deviations taken care of by (C)  No complication regarding deemed generation.  Perpetual incentive for maximizing generation and reducing drawal during deficit, but no incentive to over generate during surplus. BACK

UI IN SR (FROM 01/01/03 TO 04/12/05) TOTAL UI TURNOVER : MU TOTAL UI TURNOVER : MU TOTAL UI AMOUNT DISBURSED: CR TOTAL UI AMOUNT DISBURSED: CR AVG WEEKLY TRANSACTION:- 66 MU AVG WEEKLY TRANSACTION:- 66 MU AVG WEEKLY UI AMOUNT DISBURSED:- 13 CR AVG WEEKLY UI AMOUNT DISBURSED:- 13 CR Contd..

APKARKERTNPONDY Total UI exported(-) / Imported(+) in MUs Total amount paid in Crores Rs Average rate of UI in paise/unit SUMMARY OF UI – 153WKS (FROM 01/JAN/03 TO 04/DEC/05) Contd..

Inter Regional Links Present IR Capacity = 9,500 MW 700 MW 1200MW 2000MW 1200 MW 900 MW 30,500 MW 16,000 32,700 MW 34,500 MW MW 1650 MW Contd..

HVDC STATION KOLAR (KARNATAKA ) TALCHER ORISSA ) TALCHER KOLAR HVDC LINE LENGTH:100 KMS INTER REGIONAL LINKS CHIKKODI KOLHAPUR UJJAIN KOTLA

INTER-REGIONAL EXCHANGES DETAILS UPTO 151 WKS (Till ) WRER Net Energy Transaction 57.5 MU IMPORT BY SR 493.9MU Amount Due to SR Constituents Rs Cr. Rs Cr.* Amount Credited TO SR Constituents Rs Cr. Rs Cr. *from (when ER exchanges respective frequencies)