基于阻抗重塑的并网逆变器改进前馈控制策略

Improved Feedforward Control Strategy for Grid-connected Inverter Based on Impedance Reshaping

在弱电网下,电网电压前馈环节、数字控制延时等因素与电网阻抗发生耦合,大幅降低系统的稳定性。针对该问题,首先建立并网逆变器输出阻抗模型,分析了传统比例前馈控制方法的局限性。在此基础上提出一种基于阻抗重塑的并网逆变器改进前馈控制策略,在电压前馈通道中增加带通滤波器,分析改进系统的输出阻抗特性,该方法有效提升了系统的鲁棒性,同时在电压前馈通道中串联谐波控制器,可以进一步改善并网电流质量。最后,通过仿真和实验验证了所提策略的有效性。

Under weak grid conditions,grid voltage feedforward loop,digital control delay and other factors are cou-pled with the grid impedance,reducing the stability of the system.According to this issue,an output impedance model for grid-connected inverters is firstly established and the limitations of traditional proportional feedforward control methods are analyzed.On this basis,an improved feedforward control strategy for grid-connected inverter based on impedance reshaping is proposed.A band-pass filter is added to the voltage feedforward channel to analyze the im-proved system's output impedance characteristics.This method effectively enhances the robustness of the system.Addi-tionally,a harmonic controller is connected in the voltage feedforward channel to further improve the quality of grid-connected current.Finally,the effectiveness of the proposed strategy is verified through simulation and experiment.