多机并网逆变系统建模分析及谐振抑制研究

Research on Modeling and Control Analysis of Multi-Inverter Grid-Connected System and Resonance Suppression

考虑并网逆变器PWM调制的谐波源特性,针对多机并网逆变系统中LCL滤波器与电网阻抗耦合所引起的谐波增大甚至谐振的问题进行建模,分析其谐振机理。在逆变器电流环控制中引入电容电压反馈作为有源阻尼,使多机并网时逆变器输出电流满足并网条件。仿真对比加入有源阻尼前后多机并网的效果,证明所用的控制策略能削弱并网点电压和电流的谐振,改善并网环境。

For muhi-inverter grid-connected system and resonant problems caused by the coupling between LCL filter and the grid impedance, this paper modelled and analyzed the resonance mechanism considering the PWM generator as hartnonic sourse. And the capacitor voltage for feedback was introduced into inverter current loop as the active damping, making multi-inverter system output current meet the grid-connected condition. The simulation result proves that such control strategy can effectively suppress the resonantce of multi-inverter grid-connected system.