柔性直流输电系统的改进型相对控制策略

Improved relative control strategy for HVDC systems

针对传统柔性直流输电系统控制方法存在运行不稳定、可靠性不高等问题,在外环电压控制的基础上,加入相对控制环节,送端电压源换流器通过控制输出电压相对发电机端电压的相位角和幅值,分别控制与送端系统交换的有功功率和无功功率。采用PSCAD/EMTDC仿真软件搭建系统外环和内环的控制模型,在受端设置单相对地短路故障,仿真分析系统有功功率变化、无功功率变化、交流母线电压有效值和调制比。结果表明,故障发生后有功功率、无功功率在0.5s内迅速恢复稳定,证明所设计的控制系统具有良好的控制能力,实现了电压源换流器传输功率的独立、灵活调节。

This paper is motivated by the need for addressing the poor operation and the lower reliability affecting traditional flexible HVDC system control method.This is achieved by introducing the relative control links on the basis of the outer ring voltage control,sending terminal voltage source inverter by controlling the relative voltage of the generator output voltage phase angle and amplitude of each control and sending system of exchange of active power and reactive power,building the control models of the outer ring and inner ring of the system using PSCAD/EMTDC simulation software,setting single-phase to ground short-circuit fault at the receiving end,and simulating and analyzing the system’s active power change,reactive power change,effective value of ac bus voltage and modulation ratio.The results show that after the failure comes quicker recovery and stability in the active and reactive power within 0.5 s,proving that the designed control system with a better control ability enables the independent and flexible regulation of the transmitted power of the voltage source converter.