一种星接H桥级联型SVG直流侧电压均衡控制方法研究

Research on DC Voltage Balancing Control Method of Star Connection Cascaded H Bridge Static Var Generator

对星接H桥级联型静止无功发生器(SVG)直流侧电压均衡控制进行了深入研究,建立了三层直流侧电压均衡控制系统。第一层为总直流侧电压控制,通过产生基波正序有功电流维持三相所有H桥模块直流侧电压之和恒定。第二层为三相之间均衡控制,通过在变流器指令电压中注入零序电压实现三相功率的再分配,从而实现三相均衡;在该方法中,通过对H桥级联型SVG的输出电压和输出电流产生的功率进行前馈,以达到快速地动态调节。第三层为每相内部各模块均衡控制,通过沿电流方向微调每相各模块指令电压,使各H桥模块吸收的功率重新分配,进而保证相内所有H桥模块直流侧电压值等于给定值。最后通过实验验证了该控制方法的正确性和可靠性。

The in-depth study of the DC voltage balancing of the star connection cascaded H bridge multilevel static var generator（ SVG） has been made in this paper. And the control system with three layers of the DC voltage balance has been established. The first layer is the total DC side voltage control,which is maintained to be constant through generating the fundamental positive sequence active current. The second layer is the balancing control between three phases. Through the injection of the zero sequence voltage into the command voltage,we can make the redistribution of the three-phase power,so as to realize the DC voltage balance between three phases. In this method,through feeding forward the power generated by the grid voltage and the output current,the rapid dynamic regulation can be achieved. The third layer is the balancing control among modules in each phase. Through fine tuning the command voltage of each module in each phase along the direction of the current,we can make the redistribution of the power absorbed by each module,so as to ensure that the DC side voltage of each module in each phase is equal to the given value. Experimental results verify the correctness and reliability of the proposed control method in the end.