AVAILABILITY BASED TARIFFBy Dr.P.VENKATESH 8th December 2005 Dr. 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 8th December 2005 Dr. P. Venkatesh 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 8th December 2005 Dr. Venkatesh . P. Venkatesh . 8th December 2005 Dr. A new system of scheduling and dispatch. A system of rewards and penalties seeking to enforce day ahead pre-committed schedules. P.WHAT IS ABT ? A performance-based tariff for the supply of electricity by generators owned and controlled by the central government. which requires both generators and beneficiaries to commit for day-ahead 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 8th December 2005 Dr. Venkatesh . P. The total amount payable to the generating company over a year depends on the average availability of the plant over the year. P.COMPONENTS OF CHARGES Capacity (or) Fixed charge Energy (or) Variable charge Unscheduled Interchange charge Fixed charge It represents the fixed cost and depends on the capability to deliver MWs on a day-by-day basis. 8th December 2005 Dr. Venkatesh . 8th December 2005 Dr. P. It varies with the system frequency prevailing at the time of supply/consumption.. Venkatesh .Variable charge It comprises the fuel cost of the power plant according to the scheduled generation ie. Unscheduled Interchange Charge It comprises for the deviation from the pre-committed daily schedule. energy supplied as per a pre-committed schedule of supply drawn upon a daily basis. Venkatesh . P.UNSCHEDULED INTERCHANGE X =Actual Drawal = L – G UI = X – Scheduled Drawal IMPORT x SEB G L ~ 8th December 2005 Dr. Venkatesh . P.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 8th December 2005 Dr. P. Venkatesh DIST-C .CS-1 CS-2 CS-3 REGIONAL GRID SEB-A SEB-B SEB-C G-1 G-2 G-3 G-4 STATE SHARE SEB GRID DIST-A 8th December 2005 DIST-B Dr. 02 Linear in 0.02 Hz 600. P.02 Hz Hz step 8th December 2005 Dr.48 Hz Below 49.0 Hz & up to 592.0 Below 50.Details of UI rates with respect to frequency Average frequency of UI rate (paise / kwh) time block in Hz 50.0 50.0 49.5 Hz & up to 8.02 Hz Below 49. Venkatesh .5 Hz & above 0.5 Hz &49.0 Between 50. 5 50 50.5 8th December 2005 48 48. P.5 51 51. Venkatesh .5 Frequency(HZ) Dr.5 49 49.UI RATE 700 U I R a te (P a is e /U n it) 600 500 400 300 200 100 0 47. 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 8th December 2005 Dr. Venkatesh . P. 40%.DAILY SCHEDULING PROCESS SEBs A. 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. Venkatesh .B. Central station has availability of 900MW for the next day RLDC breaksup the schedule . P.C have allocated share of 30%.30%. 8th December 2005 Dr. 8th December 2005 Dr. P. Venkatesh . Venkatesh .Deviations from schedule High UI rate during low frequency condition induce all states to reduce their drawal from the grid by maximising own generation. During high frequency condition . curtailing their consumer load. P.state can draw extra power at low rate and encouraged to backdown its own costlier generation. Energy is metered in 15-minute time block 8th December 2005 Dr. Venkatesh .8th December 2005 Dr. P. At frequencies below 49. Provides Merit order dispatch. Cost reduces on deviating from schedule on basis of Economic Dispatch at high and low frequencies. P. Venkatesh . State will be benefited by under drawing from grid. At low frequencies states can earn UI by under drawing from Grid. 8th December 2005 Dr.6 Hz. Grid power is costlier. Grid power is cheap compared to any other source. UI rate is less.FEATURES OF ECONOMIC LOAD DISPATCH At frequency above 50 Hz. Pgr = SI + UI Pgi min " Pgi " Pgi max Ci – cost of ith generator Cgr – cost function for Grid. P.ECONOMIC DISPATCH OF POWER UNDER ABT Minimise Cgr(Pgr) + ! Ci(Pgi) Subject to Pgr + !Pgi – PD =0. Venkatesh . Cgr = UI charge + f(SI) Where UI charge = UI * UI rate 8th December 2005 Dr. 02 0.GENERATOR DATA A G1 G2 G3 G4 0.03 B 10 25 20 35 10 C 100 100 100 100 100 Dr.02 0.01 8th December 2005 . Venkatesh Pgmin (MW) 10 5 5 5 0 Pgmax (MW) 200 60 50 60 1000 Grid 0. P.01 0. Venkatesh .5 Frequency (Hz) 50 50.Load Dispatch at Different frequencies 400 Grid Gen 1 Gen 2 Gen 3 Gen 4 350 300 250 Power (Mw) 200 150 100 50 0 49 49.5 8th December 2005 Dr. P. Venkatesh . P.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 8th December 2005 Dr. Venkatesh .CONCLUSION ABT has led to drastic improvements in grid operation. P. SEB can not only minimize their costs but also help in reducing frequency deviations in the grid. 8th December 2005 Dr. Deshmukh .Saurabh Chanana .Sanjaykulkarni -National power systems conference. www. Dr. P. Economic Load Dispatch under ABT Regime – Mr.com A Presentation On Avalabilty Tariff.REFERENCES 1) 2) 3) 4) 5) Introduction to availability Based Tariff.Conference publication no:426 IEE 96.Bhusan .kalkitech.Bhanu Bhusan Abc of ABT-BHANU BHUSAN.surekha R. Availability Based Tariff : A reliable and economical experience of western grid –Mrs. Innovative tariff and metering for Indian gridsB. Mr.NPSC 2004.NPSC 2004. Venkatesh 6) 8th December 2005 . Ashwani Kumar . Dr. P. Venkatesh .THANK YOU 8th December 2005 Dr.