A Method for Unit Commitment with Transmission Losses and Flow Constraint

Researches on the unit commitment with transmission network have been reported recently. But, in most of these researches, they discussed mainly on the security constrained unit commitment, while the relationship between unit commitment and transmission losses was not considered. However, from a standpoint of operating reserve for ensuring power supply reliability, an unit commitment considering transmission losses is required. Further, under the deregulation and liberalization of electric power industry, not only line's security but also transmission losses are expected to play an important role in calculating the network access charge, and unit commitment taking into account transmission losses is also desired from this viewpoint. In this paper, an unit commitment approach with both transmission losses and line flow constraint is presented. Based on a heuristic iterative optimization method, first, an initial schedule is created by using a successively decommitting unit approach that is proposed in this paper. Then, we find out a constraints included unit commitment schedule by a heuristic iterative optimization approach, in which an algorithm being able to get rid of line overload by DC optimal power flow is developed. Through numerical simulations on two test power systems, the effectiveness of the proposed method is shown.