Short-Circuit Ratio and Short-Term Voltage Security Constrained Unit Commitment in High Wind Power-Penetrated Power Systems

For high wind power-penetrated power systems (HWPPSs), two main factors hinder wind power integration. One is the insufficient short-circuit ratio of multiple renewable energy stations (MRSCR). The other is the disconnections of wind turbines (WTs) caused by transient voltage sag/overvoltage (TVS/TOV) issues. Due to the time delay in WTs' controllers, it is difficult for WTs alone to meet the reactive power demands in different stages of the transient process. Some synchronous machines (SMs) must be retained through unit commitment (UC) scheduling to improve MRSCR and prevent the disconnection of WTs. The MRSCR and short-term voltage security constrained-UC model is a mixed integer nonlinear programming (MINLP) problem with differential algebraic equations (DAEs) and symbolic matrix inversion, which is intractable to solve. Based on the dynamic characteristics of different devices, the original model is simplified as a general MINLP model. Then, generalized Benders decomposition is applied to improve the solution efficiency. The relaxed MRSCR constraints are formulated in the master problem to improve the convergence, and the precise MRSCR constraints are formulated in the subproblems to consider voltage profiles. Case studies based on benchmark systems and a provincial power grid verify the validity and efficiency of the proposed method.