基于LCL滤波的三电平APF研究

Research on Three-level APF Based on LCL Filter

采用3阶LCL滤波器代替传统并联APF的纹波电感,兼顾到了低频段增益和高频段的衰减,通过理论分析,推导了适用于三电平变流器的LCL滤波器参数选择原则;针对APF补偿电流跟踪控制问题,采用改进型二阶广义积分器算法,消除了积分环节稳态误差,同时克服了电网频率小范围波动以及电压正、负、零序问题对积分器的影响。仿真和实验验证了该APF系统的正确性。

Taking into account the gain at low frequencies and attenuation at high frequencies, the third-order LCL filter is adopted for the active power filter （APF） in place of the traditional ripple inductor. Parameter selection rules for LCL filters applied to three- level inverters were derived through theoretical analysis. As for the compensation current tracking problem of APF, the improved second-order generalized integrator was employed to eliminate the static integral error as well as overcome the adverse effects brought about by the small fluctuation of grid frequency and the problem of positive sequence, negative sequence and zero sequence voltage components. Simulation and experimental results demonstrate the correctness of the APF system.