Optimal operation of UPQC under VA capacity constraints based on hierarchical optimization

摘要

This paper presents an optimal operation scheme for unified power quality conditioner (UPQC) under VA capacity constraints based on hierarchical optimization ideas. Three optimization objectives are taken into account in the proposed scheme and they include: (1) to minimize load voltage deviation; (2) to maximize power factor (PF) of the power grid; (3) to minimize the total apparent power of the UPQC. Because this is a multi-objective optimization problem which is not easy to solve in real-time, it is transformed into several single-objective optimization problems based on the priority of the optimization objectives. By solving the single-objective optimization problems, the operation of UPQC is divided into four simple optimal operation modes. Two case studies with different VA capacity constraints are implemented to verify the optimal operation of UPQC with the proposed method. Simulation results verify the correctness and effectiveness of the proposed method and the related performance analysis.