Resonance suppression of LCL filter for shunt active power filter via active damper

Resonance damping of LCL filter has become a crucial concern in the operation of shunt active filter inverters due to its wide control bandwidth. To address the challenges of the resonance issue, this paper proposes a novel damping method for SAPF with an LCL filter to reduce the damping losses without affecting control of SAPF. The proposed approach is based on an auxiliary converter that is connected to the filter capacitor in series. In the auxiliary converter, the resonance current is detected and injected by inverse as a controlled voltage. The stability of the proposed method is carried out by bode diagrams and compared with the conventional method. The performance of the proposed method has been validated under different cases by implementing a laboratory setup. The effectiveness of the proposed method has been validated through the theoretical and experimental results. The switching harmonic components are attenuated by 215 dB and 70 dB ratios at the 10 kHz and 20 kHz via the proposed method. Furthermore, the damping power losses are 1.9% and 0.9% for the conventional method and the proposed method, respectively. As a result, the proposed method has better switching harmonic mitigation with 1% lower damping power losses than the conventional method.