柔性直流输电系统的桥臂功率解析

This paper analyzes the faults of the flexible HVDC transmission system from the energy transferring perspective, upon which a new fault analysis method based on the arm bridge power of the flexible HVDC transmission system is proposed, which provides the basis for the analysis and solution of AC faults, DC line faults, and transient energy balance control in flexible DC transmission systems. Firstly, an equivalent circuit for AC system faults is established, and the analytical expressions for arm bridge power under AC single-phase faults, phase-phase short-circuit faults, and three-phase short-circuit faults are derived using the symmetric component method. Meanwhile, the variation characteristics of bridge arm power under AC faults are analyzed. Then, from the energy transferring point of view, a DC fault equivalent circuit is established, based on which the analytical expressions for the arm bridge power under DC line faults are derived and the changing characteristics of the arm bridge power under DC faults are analyzed. Finally, a flexible DC transmission system is established on the PSCAD/EMTDC simulation platform, and the analytical results are compared with simulation results to verify the accuracy and reliability of the proposed analytical method.