Study of Resonance Suppression Strategy and Its Adaptability for Grid-Connected Inverters in High Permeability Environment

In the high permeability environment, the use of LC (LCL) filters on the AC side of grid-connected photovoltaic inverters can effectively reduce the size and capacity of the filters. However, it can lead to filter resonance issues. The active damping control method can avoid filter resonance problems. This study take focuses on the three-level photovoltaic grid-connected inverter by using a virtual resistor based on the differential of capacitor voltage to generate capacitor current, the active damping scheme suppresses the resonance of the inverter output current without additional sensors. The robustness of this scheme under different grid short-circuit capacities is analyzed. Finally, the feasibility of the algorithm is validated on a 30 kW three-level grid-connected inverter experimental platform.