Transmission Switching in Security-Constrained Unit Commitment

Transmission switching (TS) is introduced in security-constrained unit commitment (SCUC) for alleviating transmission violations and reducing operating costs. The SCUC problem is decomposed into the unit commitment (UC) master problem and the TS subproblem. The UC master problem finds the optimal hourly schedule of generating units. The TS subproblem uses this solution for transmission switching to find the optimal dispatch of units when considering network constraints. The TS subproblem also examines contingencies and identifies required changes to the UC master problem solution when contingencies cannot be mitigated in the TS subproblem. To propose a practical TS model, the standing phase angle difference limit is considered and relevant constraints are added to the TS subproblem. The case studies exhibit the effectiveness of the proposed approach.