Reactive power optimization of AC/DC parallel operation system with VSC-MTDC

Abstract

With the development of large scale wind power integrated to the grid and the wide applications of VSC-MTDC, the traditional reactive power optimization methods can not satisfy the current parallel AC/DC system‘s operation with the integration of intermittent wind power. Based on scenarios analysis, a reactive power optimization method applied to parallel AC/DC system‘s operation is proposed considering the wind farms and VSC-MTDC. Firstly, the historical data of the wind farm output is used to fit the multi-scene probability of wind power output. Secondly, by considering the multi-scenario combination of wind farms, the objective function of minimizing the expected value of the integrated power loss under multiple scenarios is established. The reactive power optimization model with VSC-MTDC and wind farm under multi-scenario is also proposed considering the parallel AC/DC system operational constraints, which takes the system-level control strategy into account. The global optimal solution solver IPOPT is used to calculate optimal reactive power under two kinds of operations separately considering master-slave control mode and the voltage droop control mode. Finally, the case study based on Nan‘ao power grid, Guangdong, China is used to assess the effectiveness of the proposed method by comparing with two optimized solutions under the master-slave control mode and droop control mode in single scenario operation.