并网模块化多电平变换器控制研究

Study of Control of Grid-connected Modular Multilevel Converter

模块化多电平变换器(MMC)的并网应用是其最重要的应用场合。首先推导出了MMC在dq旋转坐标系中的等效模型,不同于常规的电压源型变换器,该模型显示交流输入回路的电感和等效电容均对系统控制产生影响;然后选择电感和电阻上的电压为控制对象,将其他变量作为扰动变量,大大简化了对输入电流的控制;再在外环控制方面,引入电容能量作为变量,实现了系统的线性控制,建立了系统功率响应模型,推导出了系统传递函数;最后通过实验证实了所提的控制策略的正确性。

Grid-connected application is the most important for the modular multilevel converter. In this paper,an equivalent model of the MMC in the dq synchronous reference is deduced. Different from traditional converter,this model indicates that both the inductance and the equivalent in the ac side would influence the system control. In order to simplify the control to the input currents, the voltage of the inductor and resistor is selected as the control variable and others are taken as disturbance variables. In the outer control loop,the capacitor energy is brought to realize linear control to the system,at the same time,the system power responding model is established to deduce the system transformation. Finally, experiment results verify the conclusions and the validitv of the mentioned control strategy.