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Economic Dispatch Calculation

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Introduction

` Rumman Kabir

` MohnishTuladhar

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Economic Dispatch

` What is ED` Sharing load between Generators to minimize total cost

required to supply the loads

` If Gen A costs more to produce power than Gen B, Gen A will be

controlled to produce less power than Gen B

` The Generators also have to meet all the constraints in the

system

` Energy Policy Act 2005, section 1234(b)

` ´the operation of generation facilities to produce energy at the lowest

cost to reliably serve consumers, recognizing any operational limits of 

generation and transmission facilities.´

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Savings of $3/MWh

Gen A

Gen B

$2/MWh

$5/MWh

Cost

MWhIncrease

1MW

Reduce

1MW

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Benefits

` Cost Effective` Saves cost by dispatching the cheapest combination allowable

by the system

` Saves Natural Resources

` Newer combined-cycle gas turbines (CCGT) costs less toproduce 1MWH (ERCOT showed $15/MWH savings)

` Less fuel is burned (30% less in ERCOT Example)

` Less Emissions

` Not only more efficient, less emissions per-unit fuel used (50-90% less emissions per unit fuel)

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Constraints

` Fuel` Coal

` Natural Gas

` Hydro

` Nuclear

` Wind/Solar

` Startup/Shutdown Cost

` Ramp Rate

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Constraints

` Minimum/maximum generation limits

` Minimum Up/Down time

` Transmission Limits

` Emission Constraints

` Transmission Losses

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Challenges

` Forecasting` Loads

` Natural resources

` Dynamic load changes.

` Generators take longer to startup

` Rate Curtailment programs can help

` Frequency of Dispatch affect level of costs (If you re-

dispatch every 5-10 mins rather than hours)

` EDC between multiple providers/regions

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EDC calculation

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Analysis of the Program

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Analysis continued

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Analysis continued

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Analysis continued

Total Load= 210MW

Iteration Pgen Qgen Generator cost( $/hr)

1 217.875 179 3.04E+03

2 216.699 176.07 3.14E+03

3 216.702 176.087 3.13E+03

4 216.7 176.083 3.13E+03

Matpower 216.7 176.08 3126.36

Total Load= 231MW

Iteration P Gen Qgen Generator cost( $/hr)

1 241.55 209.141 3.27E+03

2 239.404 202.391 3.43E+03

3 239.373 202.392 3.41E+03

4 239.389 202.383 3.42E+03

Matpower 239.4 202.4 3399.29

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Analysis continued

Total Load= 252

Iteration P Gen Qgen Generator cost ($/hr)

1 265.32 226.877 3.71E+03

2 262.252 202.391 3.71E+03

3 262.18 227.574 3.67E+03

4 262.185 227.086 3.69E+03

Matpower 262.2 229.6 3680.06

Total Load= 279

Iteration P Gen Qgen Generator cost($/hr)1 297.734 290.817 3.80E+03

2 292.407 266.727 4.11E+03

3 292.239 268.465 4.01E+03

4 292.153 266.837 4.07E+03

Matpower 292.1 260 4082.07

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L MP (EDC Program) vs L ambda (MatpowerOPF

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 Journal Paper review:A new formulation of Generator Penalty Factors ² Q.C L u

` A new algorithm for calculation of transmission loss penaltyfactors for generators, suitable for real time application

` Previously published techniques for generator penalty factorcalculation were derived from the power flow model withbasis upon reference bus location or internal-externalinterchange, disregarding the electrical distance betweengeneration and load

`

The new method is based purely upon the physical definitionof a penalty factor that is losses resulting from deliveringpower across the transmission network from a generator busto the loads.

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 Journal Paper Review

` Because of changing nature of a power system network, aneffective implementation of real-time penalty factor is basedupon periodic state estimator solutions in real time.

` Little attention devoted to real time penalty factor formulationin the literature in recent years.

` A generator·s penalty factor should be dependent upon the

electrical distance from the generator the load; rather in thisformulation it is dependent upon its location with respect tothe reference bus. Selection of a different reference bus wouldyield a different penalty factor.