Capacitor Current Feedback Active Damping for Shunt Active Power Filter with Output LLCL Filter

A high-order LLCL has excellent attenuation performance of ripple harmonics generated by VSI. The LLCL filter is especially effective at switching frequency to mitigate the switching ripple harmonics. However, like the other high-order filters, LLCL filter has resonance problem, which must be damped to have stable system. In literature, passive damping and active damping methods are proposed for grid-connected VSI. However, the active damping techniques have not been considered for SAPF with LLCL filter yet. Thus, in this paper, LLCL filter for Shunt Active Power Filter with Active Damping method is proposed and analyzed to suppress the resonance of LLCL filter and stabilize the control of SAPF.