Unit commitment considering expected customer interruption cost

Spinning reserve (SR) is one of the most important resources used by system operators to maintain system security, but excess amount of SR which goes against economy must be avoided. A new unit commitment model is proposed in the paper, which adds expected customer interruption cost (ECOST) into the objective function. Thus a pretty tradeoff between system security and economy can be achieved while system expected total cost is minimized. Instead of determining SR requirement according to predefined system risk index, the proposed model can automatically determine optimal SR capacity by making compromise between ECOST and system operation cost. Based on the probabilistic nature of uncertainties such as generator outages, etc., system expected energy not supplied (EENS) is expressed and simplified by unit commitment variables so as to optimize the generation and SR requirement simultaneously in unit commitment. Then, the proposed model is transformed into a mixed-integer linear programming problem which can be solved by large-scale commercial mixed-integer optimization software. Case studies indicate that the proposed model is effective in determining optimal SR capacity.