Security-constrained Unit Commitment Considering Hydro Units and AC Network Modeling by a New Hybrid Solution Method Composed of Benders Decomposition and Outer Approximation

This article presents a new hybrid solution approach based on Benders decomposition and outer approximation to solve the security-constrained unit commitment problem. The security-constrained unit commitment model includes both thermal and hydro unit commitment as well as AC network modeling. The proposed solution method decomposes the security-constrained unit commitment formulation into a master problem and sub-problem. The master problem includes a mixed-integer linear model of unit commitment, while the sub-problem contains a non-linear formulation for security-constrained economic dispatch of each time interval. The master problem accumulates linearizations (outer approximations) and Benders cuts obtained from the solution of the sub-problem. The proposed method can efficiently solve the security-constrained unit commitment problem with a low computation burden, completely satisfying diverse constraints of the problem with zero penalty terms. The proposed hybrid solution approach is tested on the well-known 9-busand IEEE 118-bus test systems and compared with some other recently published solution methods. These comparisons confirm the validity of the developed approach.