Security-Constrained Unit Commitment for Simultaneous Clearing of Energy and Ancillary Services Markets

This paper introduces a security-constrained unit commitment (SCUC) model with emphases on the simultaneous optimization of energy and ancillary services markets. Benders decomposition is used to decouple the SCUC into a unit commitment (UC) master problem and hourly network security checking subproblems. Lagrangian relaxation is used to decouple the UC problem into individual single-unit commitment problems. Dynamic programming is used to find the optimal commitment decision. A simultaneous marginal curve algorithm is proposed to find the optimal values of energy and ancillary services. A six-bus system with three units and the IEEE 118-bus system with 54 units are analyzed to illustrate the proposed model.