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Unit Commitment Effects in Economic Scheduling of Generators

Jangkung Raharjo(1*), Hermagasantos Zein(2)

(1) Telkom University, Indonesia
(2) State Polytechnic of Bandung, Indonesia
(*) Corresponding author



The generator scheduling problem seems simple, i.e., the demand should be met by generators that have been installed. On the other hand, fuel costs optimization is quite challenging. Under certain conditions, e.g., at the lowest load, generating capacity can exceed the demand when all the generators are operated. Thus, some generators should be turned off in order to minimize fuel costs. In this case, unit commitment is one of the interesting issues to be studied. It can reduce fuel costs and transmission losses in accordance with the generator power composition and location. This paper proposes a method that considers unit commitment in the optimization processes quickly and accurately. It will be considered in determining generator scheduling. The optimization process starts with the temporary results based on the direct method. The temporary results will determine whether the generator is on or off by considering the generator limits. At the same time, transmission losses will be evaluated with the B-Loss Matrix once the final results are obtained. This method has been tested with 26 buses and six generators with satisfactory results. Although the transmission losses have increased by 122.8% (i.e., increase of 64.422 MW, from 281.739 MW to 346.161 MW) compared to the results without unit commitment, the fuel costs have fallen to 85.24% (i.e., from $417,996.5 to $356,294.2) of all the generators stated commit.
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Generator Scheduling; Fuel Optimization; Turn-Off; Generator Limits; Transmission Losses

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