链式SVG补偿不平衡负载时的直流电压控制方法研究

链式静止同步补偿器每相各个功率单元的直流侧电容器分别独立,且无单独的充电回路,因此保持这些独立电容器的电压一致、直流电压平衡是装置安全可靠运行的前提。对三相三线制星形连接主电路组成的装置在补偿不平衡负载时出现的相间直流电压偏差进行了定性分析,解释了由于各相出力不一样带来的相间直流电压偏差问题。利用仿真软件PSIM,分析了负载不平衡度和该直流电压偏差的关系,并利用添加零序电压分量的方法使得各相直流电压独立可控,得到适合工程应用的SVG整体控制策略方法。

Research of DC Voltage Control Method for Cascaded-SVG Used for Unbalanced Load Compensation

The DC capacitors of cascaded-SVG power unit are independent and without individual charging circuit, so keeping the DC capacitors voltage consistent and balanceable is very important for the safe and reliable oPeration of the device. A qualitative analysis was given for the DC voltage deviation between each phase based on the device composing of star-connection main circuit with three-phase and three-wire system when used for the unbalanced load compensation, which accounted for the DC voltage deviation attributing to the differrent output of each phase. By the simulation software PSIM, it analyzed the relation between the imbalance degree and the DC voltage deviation, added zero-sequence voltage component to!make the DC voltage independent and controllable, and obtained an appropriate control strategy for engineering applications.