Research on PI and repetitive control strategy for Shunt Active Power Filter with LCL-filter

Shunt Active Power Filter (APF) has been proved as useful elements to compensate distorted currents caused by nonlinear loads in power system. To deal with the problem that conventional PI controller applied for APF cannot obtain a high compensation precision, a compound control method based on PI and repetitive control is proposed in the paper. Two different structures of the compound control method are compared, and the advantages and disadvantages are analyzed. Using the repetitive control to broaden the bandwidth of current controller, the required harmonic current can be generated at both low and high frequency; the accuracy of compensation current is improved. The PI regulator is adopted to increase dynamic response of the system. Experimental results verify the proposed method is feasible.