LCL并网逆变器改进加权电流控制方法及其鲁棒性分析

Improvement and robustness analysis of the weighted average current control based on LCL grid-connected inverter

加权电流控制方法可以使LCL并网逆变器控制系统降阶,从而提高控制系统的稳定性与带宽。但该方法不能抑制并网逆变器输出电流谐振峰,同时当滤波器电感参数偏移时,还可能造成不稳定现象。本文针对该问题,在不增加额外传感器的前提下,推演出附加不同电流反馈的改进加权电流控制方法,并进行对比择优,从而得出谐振抑制效果理想且稳态误差较小的改进方法;该方法在保持加权电流降阶特性的前提下,抑制了输出电流谐振峰,提高了整个控制算法的鲁棒性。仿真结果验证了理论分析的正确性。

The weighted average current control( WACC) method can reduce the order of control system of LCL gridconnected inverter,which will improve the stability and bandwidth of the control system. While the resonance peak of grid-connected inverter output currents cannot be suppressed by the WACC method. When the inductance of the LCL filter varies,WACC method may be unstable. To solve this problem,the improved weighted average current control methods of attaching different current feedbacks without extra sensor are discussed. An improved method is selected with better suppression effect of resonance peak and smaller steady-state error. This method damps the resonance peak of inverter output currents and improves robustness of the control system under the premise of reducing the order of the control system. The correctness of theoretical analysis is verified by the simulation results.