Dual Current Feedback Active Damping For Improving Transient Performance Of Lcl-Filter-Based Grid-Connected Inverter

This paper aims at improving transient performance of LCL-filter-based grid-connected inverters with active damping. Transient performance of inverters controlled by capacitor current feedback active damping (C(2)FAD) is analyzed, revealing that grid-currents of the inverters may have overshoot and long settling time when loads fluctuate. To improve transient response better than C(2)FAD do, a dual current feedback active damping (DCFAD) is proposed. The proposed DCFAD could realize virtual resistor connected in parallel with capacitor and virtual resistor connected in series with grid-side inductor, consequently, adding a control parameter to the algorithm to configure the poles effectively without adding sensors. Experimental results based on a single-phase grid-connected inverter prototype with LCL filter are presented to demonstrate that DCFAD could eliminate overshoot and reduce settling time, when comparing with C(2)FAD.