New Hybrid Damping Strategy for Grid-Connected Photovoltaic Inverter With LCL Filter

This paper investigates the damping performance of a grid-connected photovoltaic (PV) system with inductance-capacitor- inductance (LCL) filter and develops a hybrid damping strategies which is more robust to system parameter variations, processing delay and switching frequencies. Firstly, the comprehensive model including LCL filter, inverter and the grid are developed. Then the performance of passive damping and active damping under different grid impedances, processing delay and controller gains are investigated. Finally, a hybrid damping method combing both active and passive damping conditions is proposed. The new method can reduce the impact of processing delay and is more robust to grid impedance variations. Both simulations and experiments are provided to verify the effectiveness of the proposed method.