Coordinated Control Between Prevention and Correction of AC/DC Hybrid Power System Based on Steady-State Security Region

Abstract

Taking the Steady-state Security Region (SSR) of AC/DC hybrid power system as a link, the mathematical model of coordinated control optimization problem is established by using the complementarity between preventive control and corrective control. Firstly, taking into account the probability and severity of anticipated accidents, a two-layer optimization model of coordinated control with dynamic constraints is established with the lowest total cost of coordinated control as the objective function. Secondly, invalid anticipated accidents are eliminated based on the theory of dominant event, which reduces the scale of the model and the complexity of optimization space. Finally, based on the constraint relaxation outer-layer optimization method, the anticipated accident with the minimum Steady-state Security Distance(SSD) is eliminated from the preventive control subset and incorporated into the corrective control subset, providing fixed anticipated accident subsets for the inner-layer optimization. In the inner-layer optimization, the SSDs are used to replace the power flow equations as the constraint condition, then the nonlinear constraints are transformed into linear constraints, which can reduce the difficulty of solving the mathematical model. The transformed IEEE 39 node AC/DC hybrid system is analyzed and calculated, and the calculation results verify that the proposed method can effectively improve the efficiency of solving optimal control scheme, and provide the possibility for online application.

Keywords

• AC/DC hybrid power system
• steady-state security region
• coordinated control
• dominant event
• constraint relaxation