Novel resonance damping circuits for LCL type shunt active power filter

This paper proposes a novel damping method for the resonance problem of the LCL output filter in the active power filter (SAPF). The wide control bandwidth of the SAPF has made this problem critical. The proposed method is based on an active damping circuit, which does not affect SAPF control. It involves an auxiliary converter connected in series with a filter capacitor to detect and inject back the resonant current as the reference signal of the converter. The stability of the proposed method is analyzed using frequency response and compared to the traditional method to prove theoretical feasibility. The experimental results demonstrate the effectiveness of the proposed method, which has a better switching harmonic suppression effect compared to the traditional method.