Availability Based Tariff (ABT) in Northern Region

COORDINATES/ RLDC REGIONAL GRID IPP STATE GENR. SHARE CENTRAL

G1 G2 SERC SLDC SEB/STU State Govt. RLDC REB CTU CERC Central Govt. CEA ISTS ISGS Load L1L2 Intra State System IEGC to Operate on the periphery X=- GLG

 What is Availability Based Tariff (ABT)?  Day-Ahead Scheduling  Real time operation  Regional Energy Accounting (REA)  FAQs on ABT

Availability Based Tariff (ABT) is applicable at the regional grid level only between the ISGS stations and the SEBs/STUs. However a similar scheme between the SEBs/STUs and the GENCOs and DISCOMs within the state is desirable.

Components of inter-utility tariff (Pre – ABT Mechanism)  Fixed charges  Interest on loans  Depreciation  O & M charges  Return on equity  Interest on Working Capital  Energy charges (fuel cost)  Incentives  Surcharge & other levies  No charge for reactive energy

TENTATIVE COST FOR NTPC THERMAL STATIONS FOR THE MONTH OF DEC 2003 Station Fixed Cost Rs. Cr/yr (1) Average Fixed Cost Rs. Cr/day (2) Average Fixed Cost P / KWh (3) Variable Base Cost P / KWh (4) Variable FPA P / KWh (5) Total Variable Base Cost P / KWh (6) Composite Cost P / KWh (3) + (6) Singrauli Rihand Unchahar – I Anta GPS* Auraiya GPS* DadriGPS G) Dadri (T) Unchahar – II Dadrigas(L) *Rates for mixed fuel (gas+ liquid fuel, naphtha)

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)

Energy Charges (paise/kwh) for Central Sector stations (Dec 2003) Sl. No. Power Station Rate (Paise / KWh) 1.Salal Tanakpur Singrauli Rihand Anta/Auraiya/Dadri GT Unchahar Dadri (Thermal)

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.

UNSCHEDULED INTERCHANGE (UI) RATES Average frequency of 15 minute time block UI Rate (Paise / KWh) 50.5 Hz & Above 0.0 Below Hz & up to Hz 5.6 Below Hz & up to Hz Below Hz Between Hz & Hz (50.5 – F/0.02) x 5.6

UNSCHEDULED INTERCHANGE (UI) RATES THUS At 50.3 Hz, UI = 56 paise / KWh At 50.3 Hz, UI = 56 paise / KWh At 50.2 Hz, UI = 84 paise / KWh At 50.2 Hz, UI = 84 paise / KWh At 50.0 Hz, UI = 140 paise / KWh At 50.0 Hz, UI = 140 paise / KWh At 49.8 Hz, UI = 196 paise / KWh At 49.8 Hz, UI = 196 paise / KWh At 49.5 Hz, UI = 280 paise / KWh At 49.5 Hz, UI = 280 paise / KWh

FREQUENCY LINKED UNSCHEDULED INTERCHANGE RATES FREQUENCY (Hz) UI RATE (Paise / KWh) FREQUENCY (Hz) UI RATE (Paise / KWh)

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.

UNSCHEDULED INTERCHANGES (UI) I.E. DEVIATIONS FROM SCHEDULES  Makes all the players in the grid self-responsive 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 provides the mechanism for on-line displacement of costlier generation by cheaper generation : ultimate optimisation.

REACTIVE ENERGY CHARGES Under ABT, a reactive energy charge in paise/kwh is applicable. Under ABT, a reactive energy charge in paise/kwh is applicable. The charges would 4.0 paise/kVARh upto 31 st March 2001 and 5% per annum. The charges would 4.0 paise/kVARh upto 31 st March 2001 and 5% per annum. This would be applicable for reactive power exchanges outside the % voltage band. This would be applicable for reactive power exchanges outside the % voltage band.

TIME TABLE FOR EXCHANGE OF INFORMATION IN RESPECT OF SCHEDULING By hrs. ISGSs shall advise NRLDC the Station-wise MW and MWh capabilities By 1100 Hrs. NRLDC shall advise the States / Beneficiaries the Station wise MW & MWh entitlements. By 1500 hrs. SLDCs/ Beneficiaries shall communicate the Station-wise requisitions and details of bilateral exchanges to NRLDC. By 1700 hrs. NRLDC shall convey the ex-power plant despatch schedule to each ISGS and net drawal schedule to each State / Beneficiary. The details of unrequisitioned surpluses shall also be intimated. By 2200 hrs.* ISGSs / States / Beneficiaries shall inform the modifications, if any, for incorporating in the final schedule By 2300 hrs. NRLDC shall issue the final despatch and drawal schedule. * Since issuing the final despatch and drawal schedule is a critical activity and considerable time is involved in its preparation and carrying out requisite moderation, if any, it has been agreed to complete this activity by 2100 hrs.

Real time operation What all can happen on the day of operation? 1) Prospective revision of ISGS availability »Entitlement revised for remaining part of the day. State’s options State’s options Rework the requisitions to ensure maximum economy in the operation of power system in the state. Rework the requisitions to ensure maximum economy in the operation of power system in the state.

Real time operation 2) Tripping of an ISGS unit »Immediate frequency dip »State (SEB)’s drawal reduces and it receives UI payment State’s options State’s options Draw less than schedule & get UI Draw less than schedule & get UI Reduce net drawal further by increasing own generation & get additional UI Reduce net drawal further by increasing own generation & get additional UI Draw as per schedule & forego UI Draw as per schedule & forego UI

Real time operation 3) Tripping of the State’s own generating unit? State’s net drawal increases and it has to pay UI State’s net drawal increases and it has to pay UI State’s options Continue to overdraw and pay UI Continue to overdraw and pay UI Reduce net drawal by load-shedding or bringing up all available generation Reduce net drawal by load-shedding or bringing up all available generation Increase ISGS requisition Increase ISGS requisition Enter into bilateral with other SEBs for idle capacity, if any Enter into bilateral with other SEBs for idle capacity, if any

Real time operation 4) Load crash in the state Frequency increases and state underdraws from the grid with UI implications Frequency increases and state underdraws from the grid with UI implications State’s options Reduce own generation if respective energy rate is higher than the UI rate Reduce own generation if respective energy rate is higher than the UI rate Restore disconnected loads (if the recovery rate is higher then the UI rate) Restore disconnected loads (if the recovery rate is higher then the UI rate) Reduce ISGS requisition if ISGS energy rate is higher than the UI rate Reduce ISGS requisition if ISGS energy rate is higher than the UI rate

Real Time Operation(Gen. Units) 1.In case of tripping of machine  Intimate to RLDC – New schedule shall become effective from 4 th time block – For initial 3 time blocks, plant has to bear the UI – For initial 3 time blocks, plant has to bear the UI  Whether revival time is known – If No, Declare reduced DC for remaining part of the day If yes, Declare reduced DC for outage time and enhanced DC thereafter 2. Change in inflows: Schedule gets revised w.e.f. 6 th time block 3. Schedule change by RLDC because of Transmission constraints Schedule change w.e.f 4 th time block (New schedule) Initial 3 blocks – as per actual (SEM) Generation to be revised as per new schedule - Immediately 4. Suo-moto Rescheduling by NRLDC Initial 3 blocks –As per actual generation (SEM Reading) 4 th Block – New value for generation schedule Generation to be revised as per new schedule - Immediately Generation to be revised as per new schedule - Immediately

Special Energy Meters (SEMs) specifications 0.2 S accuracy class for active power as per IEC-687, S accuracy class for active power as per IEC-687, 1992 Static, totally tamper proof Static, totally tamper proof Two standard models-1A and 5A Two standard models-1A and 5A Non-volatile memory for ten days Non-volatile memory for ten days Harmonics filtered out and only the fundamental energy recorded Harmonics filtered out and only the fundamental energy recorded

SEM Specifications (contd..) Recording in secondary quantities. CT/CVT ratios to be applied at control centre. Recording in secondary quantities. CT/CVT ratios to be applied at control centre. Net energy (Wh) exchange in each 15-minute block Net energy (Wh) exchange in each 15-minute block Cumulative Wh transmittal at each mid-night. Cumulative Wh transmittal at each mid-night. Average frequency in each 15-minute time block stores as a two-digit code. Average frequency in each 15-minute time block stores as a two-digit code. Cumulative reactive energy register for voltage below 97% Cumulative reactive energy register for voltage below 97%

SEM Specifications (contd..) Cumulative reactive energy register for voltage above 103% Cumulative reactive energy register for voltage above 103% High accuracy of internal clock (one minute per month or better) with restricted advance/retard facility. High accuracy of internal clock (one minute per month or better) with restricted advance/retard facility. VT supply disturbance time tagged with * mark VT supply disturbance time tagged with * mark No separate auxiliary supply- only optical coupler for data collection. No separate auxiliary supply- only optical coupler for data collection. Calibration once in five years at a test lab (0.05 accuracy class test equipment or better) Calibration once in five years at a test lab (0.05 accuracy class test equipment or better) On-site accuracy check once a year using portable 0.2S test equipment On-site accuracy check once a year using portable 0.2S test equipment

Regional Energy Accounting (REA) Monday to Sunday is the weekly accounting period Monday to Sunday is the weekly accounting period SEM readings collected and transferred to RLDCs on Monday/Tuesday SEM readings collected and transferred to RLDCs on Monday/Tuesday Processed data forwarded to REBs on Thursday Processed data forwarded to REBs on Thursday Weekly UI account issued by REBs on Tuesday Weekly UI account issued by REBs on Tuesday

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