ABT OPT

8th December 2005 Dr. P. Venkatesh

AVAILABILITY BASED TARIFF

ByDr.P.VENKATESH


CONTENTS� Introduction�What is ABT ?�Why ABT is necessary?�Components of charges�Working of ABT mechanism�Daily scheduling process�Economic Dispatch of power under ABT�Benefits offered by ABT�Conclusion


INTRODUCTION

� It is a solution for technical and commercial problems in Regional Grid operations in India.

�For balancing of generation and load demand

�To have reliable and quality of electricity


WHAT IS ABT ?

�A performance-based tariff for the supply of electricity by generators owned and controlled by the central government.

�A new system of scheduling and dispatch, which requires both generators and beneficiaries to commit for day-ahead schedules.

�A system of rewards and penalties seeking to enforce day ahead pre-committed schedules.


WHY ABT IS NECESSARY ?

� Present tariff encourages grid indiscipline

� ABT provides incentive for backing down the generation during off peak hours and for enhancing the output capability of power plant

� Discourages over drawing during peak hours

� Promotes grid discipline


� Capacity (or) Fixed charge� Energy (or) Variable charge� Unscheduled Interchange chargeFixed charge

It represents the fixed cost and depends on the capability to deliver MWs on a day-by-day basis.

The total amount payable to the generating company over a year depends on the average availability of the plant over the year.

COMPONENTS OF CHARGES


Variable chargeIt comprises the fuel cost of the power

plant according to the scheduled generation ie., energy supplied as per a pre-committed schedule of supply drawn upon a daily basis.

Unscheduled Interchange ChargeIt comprises for the deviation from the

pre-committed daily schedule. It varies with the system frequency prevailing at the time of supply/consumption.


UNSCHEDULED INTERCHANGE

~

xSEB

G L

IMPORTX =Actual Drawal = L – G

UI = X – Scheduled Drawal


WORKING OF ABT MECHANISM

�Central generating stations deliver their expected output for the next day to RLDC

�RLDC break up and tabulates ,conveys to SLDC

�SLDC carryout exercise to see how best they can meet the load of their consumers and convey to RLDC

�RLDC compiles and determines the schedule for generation/drawal

�Deviations from the schedules are determined in 15 minutes time block by special metering


REGIONAL GRID

CS-2 CS-3

SEB-A SEB-B SEB-C

CS-1

SEB GRID

G-1 G-3STATE SHARE

DIST-A DIST-B DIST-C

G-2 G-4


Details of UI rates with respect to frequency

Linear in 0.02 Hz step

Between 50.5 Hz &49.02 Hz

600.0Below 49.02 Hz

592.0Below 49.0 Hz & up to 49.02 Hz

8.0Below 50.5 Hz & up to 50.48 Hz

0.050.5 Hz & above

UI rate (paise / kwh)Average frequency of time block in Hz


UI RATE

0100200300400500600700

47.5 48 48.5 49 49.5 50 50.5 51 51.5

Frequency(HZ)

UI R

ate

(Pai

se/U

nit)


CHARGE COMPONENTS

�Fixed charge=A function of the Ex-bus MW availability of power plant for the day declared before the day starts X SEB’s % share

�Variable charge=Mwh for the day as per Ex-bus drawal schedule for the SEB finalised before the day starts X Energy charge rate

�UI charge= ∑(Actual energy interchange in a 15 min time block –Scheduled energy interchange for the time block) X UI rate for the time block

�Total payment for the day = Fixed charge + variable charge ± UI charge


DAILY SCHEDULING PROCESS

�SEBs A,B,C have allocated share of 30%,30%,40%.

�Central station has availability of 900MW for the next day

�RLDC breaksup the schedule .�SLDC carry out exercise how best to meet the

load�SEBs A,B have 270 MW for 24hour period�SEB C has 360 MW during daytime and 200MW

during night hours.


Deviations from schedule

�High UI rate during low frequency condition induce all states to reduce their drawal from the grid by maximising own generation, curtailing their consumer load.

�During high frequency condition ,state can draw extra power at low rate and encouraged to backdown its own costlier generation.

�Energy is metered in 15-minute time block


FEATURES OF ECONOMIC LOAD DISPATCH

�At frequency above 50 Hz, UI rate is less. Grid power is cheap compared to any other source.

�At frequencies below 49.6 Hz, Grid power is costlier. State will be benefited by under drawing from grid.

�Provides Merit order dispatch.�Cost reduces on deviating from schedule on

basis of Economic Dispatch at high and low frequencies.

�At low frequencies states can earn UI by under drawing from Grid.


ECONOMIC DISPATCH OF POWER UNDER ABT

MinimiseCgr(Pgr) + ∑ Ci(Pgi)

Subject to Pgr + ∑Pgi – PD =0.Pgr = SI + UIPgi min ≤ Pgi ≤ Pgi max

Ci – cost of ith generatorCgr – cost function for Grid.Cgr = UI charge + f(SI)Where UI charge = UI * UI rate


GENERATOR DATA

10000100100.01Grid

605100350.03G4

505100200.02G3

605100250.02G2

20010100100.01G1

Pgmax(MW)

Pgmin(MW)

CBA


Load Dispatch at Different frequencies

49 49.5 50 50.50

50

100

150

200

250

300

350

400

Frequency (Hz)

Pow

er

(Mw

)

GridGen 1Gen 2Gen 3Gen 4


BENEFITS OFFERED BY ABT

� Limits high frequency periods�Better grid discipline�Planning of load generation balance�Strategic overdrawals/underdrawals�Utilization of other resources� Improved bilateral exchanges


CONCLUSION

ABT has led to drastic improvements in grid operation. SEB can not only minimize their costs but also help in reducing frequency deviations in the grid.


REFERENCES

1) Introduction to availability Based Tariff, www.kalkitech.com

2) A Presentation On Avalabilty Tariff,Bhanu Bhusan3) Abc of ABT-BHANU BHUSAN.4) Innovative tariff and metering for Indian grids-

B.Bhusan ,Conference publication no:426 IEE 96. 5) Availability Based Tariff : A reliable and economical

experience of western grid –Mrs.surekha R. Deshmukh , Dr.Sanjaykulkarni -National power systems conference,NPSC 2004.

6) Economic Load Dispatch under ABT Regime –Mr.Saurabh Chanana , Mr, Ashwani Kumar ,NPSC 2004.


THANK YOU

ABT OPT

Documents

Transcript of ABT OPT