An active damping method based on PR control for LCL-filter-based grid-connected inverters

LCL filter is more effective in reducing high order harmonic frequency, but it brings stability problems. In order to assure stable operation, different passive and active damping methods have been proposed. The passive damping methods need damping resistor and reduce the efficiency of the system, and active methods usually need extra sensors. This paper proposed a sensorless active damping method with proportional resonance controller for LCL-based gird-connected inverters. Theoretical analyses and control structure of the selected method are presented in this paper. The proposed method is verified by simulation results.