The LCL Type Three-Phase Grid-Connected Inverter Active Damping Design Based on Capacitor Current Feedback

Distributed generation systems based on renewable energy are one of the important ways to cope with the energy crisis and environmental pollution. As an energy conversion interface between renewable energy generation units and the grid, the LCL type grid-tied inverter converts direct current into high-quality alternating current and feeds it into the grid. However, LCL grid-connected inverter has obvious attenuation effect on high-frequency harmonics, but there is a resonance problem, and solving this problem is of great significance for the safe, stable and efficient operation of RE-DPGS. Capacitor current feedback active damping can effectively reduce the resonant peak of the LCL filter, which is equivalent to combining a resistor on the filter capacitor under analog control. In this paper, by analyzing the error of steady-state grid-connected current, as well as the phase margin and amplitude margin of the system, the capacitor current feedback coefficient value range that meets the above requirements is obtained.