Commercial and ABT proper description. Ppt

ABT

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PresentationPresentation
onon
Why & What is Why & What is
ABT –ABT –
The FundamentalsThe Fundamentals
BY
SH. S.D. TRIPATHISH. S.D. TRIPATHI
EXECUTIVE DIRECTOR(COMML)
NATIONAL HYDROELECTRIC POWER
CORPORATION LTD.
FARIDABAD

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WHY
AVAILABILITY BASED
TARIFF ?

3. 3
TARIFF MECHANISMS – Pre ABT
Single Part
Tariff
 No Commercial signals
 Not conducive to motivate & encourage economic generation of power & its absorption
 Not conducive to ensure optimisation of integrated operation of the grid system
 Disputes relating to backing down during off-peak hours
 Giving feeling to SEBs about over recovery of fixed expenses & operating costs

by Generators
 At times was leading to spilling of zero-cost water energy at hydro stations

4. 4
TARIFF MECHANISMS – Pre ABT
Two Part
Tariff

“Fixed Charges” & “Variable Charges” of the Plants were separated.
 Some commercial signals could be introduced by bringing in the
“Availability Factor”.
 But no provisions for inculcating grid discipline.

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GROUNDS NECESSITATING INTRODUCING ABT
 Undisciplined and haphazard operation of Regional Grids
 Large deviations in frequency from that of normal frequency
 Chronic surpluses in Eastern & North-Eastern Region and shortages in Northern &
Western Regions resulted in substantial functioning of Regional Grids at frequencies
which are far beyond even the normal band liberally defined by IEGC i.e. 49.0 to 50.5 Hz
 Continued operation at such abnormal frequencies results in long term damages to
generation and end-user equipments
 No incentives in earlier Tariff mechanisms for the following :-
 Backing down of generation during off-peak hours
 Reducing consumer load/ enhancing of generation during peak-load hours
 It was profitable to go on generating at a high level even when consumer demand has
come down
 In totality, earlier Tariff Mechanisms having no provisions to introduce grid-discipline
and rather it encouraged grid-indiscipline

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WhatWhat
is is
ABTABT
??

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WHAT IS ABT ?
“Availability Based Tariff (ABT)”, as its name implies, is a rational tariff structure
based on “AVERAGE AVAILABILITY (MW delivering capability)” of the plant over
the year for supply of power from Central Generating Stations to the beneficiaries
on a long term contracted basis
ABT mechanism treats the fixed and Variable Cost components of a plant
separately
Only the Fixed Cost (F.C.) element is linked with the availability of the plant and is
recoverable in the following manner :-
PLANT AVAILABILITY RECOVERY
As per specified norms Full F.C.
Higher than norms Full F.C. + Incentive
Lower than Norms Prorata reduced F.C.
It enforces a well coordinated system of scheduling and despatch, which
requires both generators and beneficiaries to commit to day-ahead schedules
though variations are permitted if notified in advance as per specified
provisions
It provides rewards/penalties for deviations from schedule for
helping/disturbing the GRID as the case may be.

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ELEMENTS
OF
ABT
FIXED COST
i.e. Capacity Charge
VARIABLE COST
i.e. Energy charge
UNSCHEDULED INTERCHANGE
(U.I.) CHARGE
To reimburse
fixed cost of the
Plant linked with
the Availability of
the Plant
To reimburse Fuel cost
for Scheduled
Generation
A payment for deviations
from schedule at a rate
dependent on system
conditions

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COMPONENTS
OF
FIXED COST
INTEREST
ON
LOAN
DEPRECIATION RETURN
ON
EQUITY
O&M
EXPENSES
INTEREST
ON
WORKING
CAPITAL

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MECHANISM FOR SHARING OF CHARGES AMONG
BENEFICIARIES UNDER ABT
a)CAPACITY CHARGES
Paid in proportion to the share of the beneciaries in respective plants
Shares of beneficiaries in Central Generating Stations of different stations are
notified by MoP as per Gadgil Formula
Payment dependent on declared output capability of the plant for the day and
beneficiary’s percentage share in the plant and not on power/ energy
intended to be drawn or actually drawn
b)ENERGY CHARGES
Paid as per the Energy Scheduled to be supplied from the plant to the
beneficiary during the day and not as per his actual drawal
Any excess drawal beyond schedule shall be governed at rate dependent on
system frequency

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UNSCHEDULED INTERCHANGE CHARGE (U.I.)
Variation between actual generation /drawal and scheduled
generation/drawal shall be accounted for through unscheduled
interchange (UI) charges
 UI for generating station shall be equal to its actual generation minus its
scheduled generation.
UI for a beneficiary shall be equal to its total actual drawal minus its total
scheduled drawal.
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 and the rates linked with the same

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UNSCHEDULED INTERCHANGE CHARGE (U.I.)
45 p/Unit for
every 0.1 Hz
decline
UI Rate wef 1
st
October 2004
Kink at 49.80
Hz
30 p/Unit for
every 0.1 Hz
decline
FREQUENCY (Hz)
R
A
T
E

(
P
/
K
W
H
)
UNSCHEDULED INTERCHANGE (UI) RATE

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ABT - OPERATING MECHANISM
CENTRAL GENERATING COMPANIES (CGS)
REGIONAL LOAD DESPATCH CENTRE (RLDC) OF THE CONCERNED
REGION
STATE LOAD DESPATCH CENTRE (SLDC) OF THE STATES IN THE
REGION
SEBs IN THE REGION
a) AGENCIES INVOLVED

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R
E
G
I
O
N
A
L

G
R
I
D
CONTROLLED BY RLDC
P
O
W
E
R

F
R
O
M
C
G

S
T
A
T
I
O
N
S
DRAWAL
BY
REGIONAL
SEBs
ABT - OPERATING MECHANISM
I
N
T
R
A
-
S
T
A
T
E

G
R
I
D
CONTROLLED BY SLDC
POWER FROM
CAPTIVE IPP &
OTHERS
STATES
OWNED GEN.
STNS
D
R
A
W
A
L

B
Y

S
T
A
T
E
D
I
S
C
O
M
S
CGS
POWER

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DAY AHEAD SCHEDULING
9am
10 am
3 pm
5 pm
10 pm
11 pm
ISGS advise foreseen station wise ex-bus MW and MWh availability
for next day.
RLDC breaks it up and advises SLDCs (beneficiaries) their shares in the foreseen
availability of ISGS.
SLDCs receives availability status of their intra-state stations also and after proper
analysis furnish their time-wise requisitions from above, and schedule of bilateral
exchanges, if any
RLDC issues” Dispatch schedules” for ISGS and “Drawal schedules” for
Beneficiaries, for the next day starting at midnight ,00 Hours.
SLDCs/ ISGS may inform any modifications to RLDC, if required
RLDC after consulting the concerned constituents issues the “Final Schedules” and
the same are frozen for the next day.

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SCHEDULING – Provisions for revision
In the event of bottleneck in evacuation of power due to any constraint,
outage, failure or limitation in the transmission system, RLDC revise
the schedule, which is effective from 4
th
time block.
In case of forced outage of a unit , the RLDC revise the schedules on
the basis of declared capacity by the ISGS, which is effective from 4
th

time block.
RLDC may refuse any revision of schedules if revision sought is less
than two percent of the previous schedules
For any Grid disturbance all schedules shall be deemed to have been
revised as per actuals for all time blocks affected by the disturbance
After completion of 24 hours operation RLDC shall issue the
implemented schedule, which shall be datum for Commercial
Accounting

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IMPLEMENTATION STATUS OF ABT
Availability Based Tariff (ABT) has been implemented w.e.f.
 01.07.2002 in Western Region,
 01.12.2002 in Northern Region,
 01.01.2003 in Southern Region,
 01.04.2003 in Eastern Region
 01.11.2003 North - Eastern Region

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HOW ABT HAS ADDRESSED DEFICIENCIES OF PRE-ABT
TARIFF MECHANISMS
Streamlined Grid Operations & Infused Grid discipline among the players of Grid
by introducing incentives/disincentives for helping/disturbing the grid.
Maximised generation from power plants through incentives for increased plant
availability.
More load demand could be met during peak-hours by enhancing output
capability of plants.
No financial loss to generators due to backing down during off-peak hours.
Encouraged ‘Merit-Order-Operation’ through clear separation of fixed and
variable charges and pit Head stations do not have to back down normally.
Allocation of power to the beneficiaries from CGS could get a real meaning
which was previously missing.
Beneficiaries are discouraged for overdrawal during peak hours due to separate
frequency based higher rate for such over drawals.
Extra payment so collected (U.I. charges) goes to beneficiaries who received
less than scheduled energy as incentive/compensation.

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IMPROVEMENTS DUE TO ABT
Improvement of Grid condition due to the implementation of ABT
 FREQUENCY PROFILEFREQUENCY PROFILE :
There has been considerable improvement in frequency profile of the
Regional Grids month after month after the implementation of ABT.
During the entire year (2005-06) of ABT period grid frequency in Northern
grid remained in the normal band of 49.5Hz-50.50 Hz for 72.25 % of the
time . The average frequency was 49.37% against 76% for the
corresponding pre-ABT period. It remained below 49.0 Hz for 26.76% of
time and above 50.5 Hz for only 0.98% of the time

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IMPROVEMENTS DUE TO ABT
 VOLTAGE PROFILEVOLTAGE PROFILE
The voltage profile has also shown considerable improvement after the
implementation of ABT.
 MERIT ORDER DESPATCHMERIT ORDER DESPATCH
Merit order despatch is now also being followed by the constituents going
by their station-wise requisition. After implementation of ABT, the pithead
stations are being scheduled upto 99% of their DC, combined cycle ISGS
is being scheduled to only 81.3% of the DC (on account of less off-take
from liquid fuel firing). This is in contrast to the pre-ABT period when the
requisition from pithead was lower than the post-ABT period while that
from combined cycle was higher than the post-ABT period.
 With improved Grid conditions, chances of damages to Generation & other
equipment down the line got reduced substantially

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IMPROVEMENTS DUE TO ABT
 Open access, wheeling of captive generations and power
trading have become possible through the UI mechanism for
handling deviations/ mismatches
 Hydro electric generation is being harnessed more
optimally than before

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IMPROVEMENTS DUE TO ABT

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IMPROVEMENTS DUE TO ABT

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IMPROVEMENTS DUE TO ABT

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MINIMUM VOLTAGE RECORDED AT DADRI 400 KV BUS
DECEMBER, 2002 TO NOVEMBER, 2003 Vs CORRESPONDING PRE-ABT PERIOD
VOLTAGE PROFILE
IMPROVEMENTS DUE TO ABT

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NEED FOR INTRA-STATE ABT
 ABT has so far been implemented only for Central sector generators and the concerned
beneficiaries who are directly connected to and are a player on the regional grids (Inter-
State only).
 Presently there is no incentive for Intra-State Stations to maximise their availability.
Implementation of ABT at Intra-State level shall help optimally utilise the Intra-State
resources
 The responsibility of grid discipline should be shared by all the inter-state constituents
such as generators, distribution licensee & bulk consumers etc.
 At present the complete power purchase cost/UI charges of Discom/SEBs is being
passed on to consumer via retail tariff. There is no incentive or penalty for Discom/SEBs
to comply with ABT regime.
 Existing capitve & co-generation also need to be tapped fully, which can be put into
effect by implementing intra-state ABT.
 The National Electricity Policy has also advised the SERCs to introduce ABT at intra-
state level within one year.
 Recently, Gujarat Electricity Regulatory Commission has ordered vide order No.3 of
2006 dated 11
th
August, 2006 for implementation of ABT at intra-state level with a trial
period for three months.

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