Network-constrained thermal unit commitment fortexhybrid AC/DC transmission grids under wind power uncertainty

The day-ahead energy and reserve management considering transmission restrictions and voltage security limits is a challenging task for large-scale power systems in the presence of volatile renewable energy sources. In this paper, a two-stage robust optimization model is proposed for the joint scheduling of energy and reserve for hybrid AC/DC transmission grids. The optimal schedule, including the commitment, power dispatch, and reserve allocations is computed subject to the feasibility of nonlinear AC and DC network constraints under a specified set of scenarios. Furthermore, the proposed decomposition approach renders the second stage (network security evaluations) into standard optimal power flow problems, which addresses the scalability issues observed with existing methods. A second-order cone relaxation is applied to nonlinear AC and DC network constraints to improve the computational tractability. In simulations, the proposed robust optimization model is illustrated using a recently proposed hybrid AC/DC transmission grid architecture with a specific topology. The results demonstrate the effective utilization of the grid capacity to accommodate more demand and renewable energy sources. This hybrid AC/DC transmission grid architecture induces exactness of the convex relaxation, supporting the validity of the optimal day-ahead schedule. The efficiency and computational performance of the proposed method is compared to the existing literature and the robustness is verified using an out-of-sample analysis.