ABT (Availability Based Tariff) - UI (Unscheduled Interchange)

Availability Based Tariff was implemented in India in 2002-03. This presentation includes the chloronological sequence of events that led to the implementation of ABT . This also introduced a new concept of UI (Unscheduled Interchange) to rein in the wide excursion of grid frequency beyond the acceptable limits by imposition of fiscal disincentives for grid indiscipline by any regional or intra-regional entity

1. AVAILABILITY BASED TARIFF-UI
MECHANISM
By S.KEJRIWAL
Executive Engineer(Commercial)
ERPC, KOLKATA

2. Sequence of Events
•Two part Tariff since 1992 (K.P.RaoCommittee
Report)
•Till late 90’s Govt of India determined tariff as
per Section 43A(2) of the Electricity Supply
Act, 1948
•Deficiencesof tariff regime
•Govt appoints M/s ECC,USA in 1994 to
prepare and submit a report

3. •The study funded by ADB
•M/s ECC,USA submits report in Nov,1994
•Suggests implementation of ABT
•Govt constitutes NTF/RTFs in 1995 to study
the report
•CERCestablishedunderElectricityRegulatory
CommissionsAct,1998toregulatetariff
ownedbyGencosownedandcontrolledby
centralgovtw.e.f15.05.1999
Sequence of Events.....contd

4. •Govtpursueditsefforts,helddueconsultations
andfinallyforwardedtheECCreportalongwith
NTFminutesandanoteonABTtoCERCinMay
1999
•ThematterwasheardinCERCfrom26-28
th
of
July,1999
•CERCissuedABTorderdated04.01.2000
•OrderstayedvariousHighcourtsofthecountry
duetoobjections/apprehensionsexpressedby
variousSEBs/GENCOs
•Hon’bleSupremecourtfinallyvacatedthestay
Sequence of Events.....contd

5. Implementation of ABT:
ABT was finally implemented in India in the
following manner:
•From 01.07.2002 in WR
•From 01.10.2002 in NR
•From 01.01.2003 in SR
•From 01.04.2003 in ER
•From 01.11.2003 in NER

6. Basic Problems in Pre-ABT regime
•Low freq during peak time
•High freq during off-peak time
•Rapid and wide changes in freq ( apprx1 Hz in
5-10 minutes)
•Frequentgriddisturbanceresultingintripping
ofgeneratingstations,interruptionofsupply
tolargeblocksofconsumersand
disintegrationofregionalgrid

7. •Damages caused at both load and generation
ends remained unquantifiedand unevaluated
•Operational/Commercialdisputes/disagreements
amongstvariousutilitiesduetoconflictof
interest
•Absenceofsuitableincentivesanddisincentives
forthoseresponsiblefortheproblem
•Lackofadequategeneration,transmissionand
distributioncapacity
Basic Problems in Pre-ABT regime

8. Possible Solution
•Maximization of generation along with load
curtailment during peak hours
•Backing down of generation to match low
demand during off-peak hours
•Imposing suitable incentives/disincentives to
ensure efficient grid operation
•Enhancing generation and transmission
capacity
•Demand side management

9. PRE-ABT TARIFF STRUCTURE:
TWO PART TARIFF:
FIXED CHARGE:
•Return on equity
•O & M expenses
•Interest on loan
•Interest on Working capital
•Depreciation
•Income Tax

10. 2. VARIABLE CHARGE:
•Primary fuel –Coal/gas
•Secondary fuel –Oil
BothFixedCostaswellasVariableCostswere
chargedtothebeneficiariesintheproportionof
actualenergydrawnbythemduringaperiod
PRE-ABT TARIFF STRUCTURE:

11. ABT TARIFF STRUCTURE:
THREE PART TARIFF:
1.FIXED CHARGE:
•Generators assigned target availability
•Totalfixedcostpayabletoageneratorovertheyearis
linkedtotheaverageannualavailability.Hencethename
AvailabilityBasedTariff
•Charged to beneficiaries in the proportion of their share in
the generating station
2. VARIABLE CHARGE:
•Charged to beneficiaries to the extent of their drawal
schedule

12. ABT TARIFF STRUCTURE:
THREE PART TARIFF:
3. UNSCHEDULED INTERCHANGE(UI) CHARGE:
•Actual Generation –Scheduled Generation (For
Generators)
•Total Actual Drawal–Total Scheduled Drawal
(For Beneficiaries)
•Worked out for each 15 min time block
•Based on average frequency of the relevant time
block

13. ABT TARIFF STRUCTURE:
THREE PART TARIFF:
3. UNSCHEDULED INTERCHANGE(UI) CHARGE:
•Overdrawal/Underinjectionunder low freq
(Penalty)
•Overinjection/Underdrawalunder high freq (Nil
or low reward)
•Overdrawal/Underinjectionunder high freq (Nil
or low Penalty)
•Overinjection/Underdrawalunder low freq
(Reward)

14. ADVANTAGES OF ABT:
•Incentivises generators to maximise generation
during peak hours
•No financial loss due to backing down of
generation during off peak hours
•Facilitates merit order despatch
•Better system operation
•Ensures grid discipline

15. ADVANTAGES OF ABT:
•Introduces transparency and works as
vigilance
•Opens avenue for interstate, inter-regional
bilateral trading of power
•Harness surplus captive generation
•Embedded generators can sell surplus
power to other SEBs

16. UI ACCOUNTING –PRELIMINARY PROCESS AND
ROLE OF RLDCs:
SCHEDULING:
•Each day of 24 hours starting from 00.00 hours be
divided into 96 time blocks of 15 minutes each
•Each generating station is to make advance
declaration of its capacity for generation in terms
of MWhdelivery ex-bus for each time block of
the next day
•Based on the above declaration, concerned RLDC
shall communicate to the various beneficiaries
their respective shares of the available capability

17. UI ACCOUNTING –PRELIMINARY PROCESS AND
ROLE OF RLDCs:
SCHEDULING:
•Afterthebeneficiariesgivetheirrequisitionfor
powerbasedonthegenerationschedules,the
RLDCshallpreparethegenerationschedulesand
drawalschedulesforeachtimeblockaftertaking
intoaccounttechnicallimitationsand
transmissionconstraints
•The schedule of actual generation shall be
quantified on ex-bus basis for generators
•scheduled drawalsshall be quantified at their
respective receiving points for beneficiaries

18. UI ACCOUNTING –PRELIMINARY PROCESS AND
ROLE OF RLDCs:
SCHEDULING:
•In case of any forced outage of a unit, or in case of any
transmission bottleneck, RLDC will revise the
schedules.Revisionwill be effective from 4
th
time block
•Anybeneficiary/generatormayalsorequestRLDCfor
revisionofSchedule.Revisionwillbeeffectivefrom6
th
time
block
•RLDCisalsoentitledtorevise(ifneedbe),theschedules
duringthedayintheinterestofbettersystem
operation.Revisionwillbeeffectivefrom4
th
timeblock
•In the event of any grid disturbance, the schedules of both
generation and drawalshall be deemed to have been
revised to be equal to their actual generation/drawal

19. UI ACCOUNTING –PRELIMINARY PROCESS AND
ROLE OF RLDCs:
METERING AND METERDATA PROCESSING:
ABT complaint Special Energy Meters (SEM of appropriate
accuracy class) to be installed by CTU at :
•HV side of GT (For Generators)
•All outgoing feeders (For Generators)
•Auxiliary and Station Transformers (For Generators)
•CTU-State interface including state end (For
States/beneficiaries)
•Both ends of inter-state tie lines (For States/beneficiaries)
•Inter-regional interfaces

20. UI ACCOUNTING –PRELIMINARY PROCESS AND
ROLE OF RLDCs:
METERING AND METERDATA PROCESSING:
Special Energy Meter (SEM) records :
•15mintimeblockwiseActualenergydrawal/injection
startingfrom00hrsfor96blocks
•CumulativeWhr
•Reactiveenergydrawal/injectionfortheentiredayatHV
condition
•Reactiveenergydrawal/injectionfortheentiredayatLV
condition

21. UI ACCOUNTING –PRELIMINARY PROCESS AND
ROLE OF RLDCs:
METERING AND METERDATA PROCESSING:
•AllRegionalentitiesincludingbeneficiaries/generatorsare
responsiblefordownloadingrawmeterdataandsendingitto
RLDC
•RLDCtofurtherprocessthedataandtransmittheprocessed
datatoRPCforaccountingpurpose
•RLDCtoalsosendtimeblockwisefrequencyforeachdayofthe
weekalongwithtimeblockwisescheduleforeachregional
entityforeachdayoftheweek
•RLDCtoalsointimateanydiscrepancywithrespectto
addition/outageofanylineinthenetworkofanyentity,outage
ofanygeneratingunit,anyerroneousmetering,andanyother
informationhavingcommercialimplication

22. UI ACCOUNTING –ROLE OF RPCs:
•DesignprogramaspertherelevantCERCRegulation
incorporatingvariousrate/volumecappingsandUI
ratevectorforaccounting
•Every week download the processed meterdate
along with schedules and frequency sent by RLDC
•Incorporate the changes/discrepancies in the
network and metering with respect to the previous
week
•Feedinputs(Actual,Scheduleandfrequency)tothe
program

23. UI ACCOUNTING –ROLE OF RPCs:
•CalculateTotalActualdrawal/injection,Schedule
drawal/injectionandUI/Deviationchargesincluding
additionalUI/Deviationchargesforeachregionalentityfor
eachdayoftheweek
•CalculateTotalActualdrawal/injection,Schedule
drawal/injectionandUI/Deviationchargesincluding
additionalUI/Deviationchargesforeachregionalentityfor
entireweek
•Apportion any pool surplus/deficit among the beneficiaries
•Issue the final weekly account and publish in the website
•Revise the account as and when required

24. UI Rate Vector
In 2000 CERC ABT order, Frequency band fixed at
50.5 Hz to 49.5 Hz
UI Rates :
•For f > 50.5, R=0
•For 49<f<50.5, R increases at 4.8 p/u for every
0.02 Hz decrease
•At f=49, R= 360p/u (subsequently revised to 420
p/u)
•Maximum UI rate linked to price of diesel
generated power

25. UI Rate Vector
In 2004 CERC Tariff regulation effective from 01.04.2004:
UI Rates :
•For f > 50.5, R=0
•For 49<f<50.5, R increases at 8 p/u for every 0.02 Hz
decrease
•At f=49, R= 600p/u (subsequently revised to 570 p/u
w.e.f01.10.2004)
•ForCentralSectorgeneratingstations,Actual
generationrestrictedto105%ofDCinatimeblockand
101%ofDCoveraday

26. UI Rate Vector
NRLDC filed a petition in CERC in 2006 praying
for increase in UI rate alongwithimposition of
volume capping:
Reasons:
•Consistent low freq
•Deliberate disabling of UFR
•Non requisitioning of liquid fuel generation
•Payment defaults

27. UI Rate Vector
•On 26.04.2007 CERC issued notification for UI charges
where maximum UI rate was 930p/u.
•Challenged by UPPCL in Allahabad High court
•Suomotopetition in june2006
UI Rates:
•For f > 50.5, R=0
•For 49.8<f<50.5, R increases at 6 p/u for every 0.02 Hz
decrease
•At f=49.8, R= 210p/u
•For 49.5<f<49.8, R increases at 9 p/u for every 0.02 Hz
decrease
•At f=49.8, R= 345p/u
•For 49<f<49.5, R increases at 16 p/u for every 0.02 Hz
decrease
•At f=49.8, R= 745p/u