Multi-Resonance Control and Phase Margin Compensation Method of Grid-Connected Inverter Based on Voltage and Current Feedforward

In this paper, the feedforward strategy of grid voltage is adopted to suppress the influence on grid-connected current caused by grid voltage. To eliminate the resonant peak of the LCL type filter, the capacitive current feedforward strategy is used to provide active damping. For the weak current network, a multi-resonance link is added based on grid voltage feedforward, for keeping the feedback characteristics only at the main low-frequency harmonics of the power grid and increasing the phase margin in the middle and high frequency band of the resonance frequency. To overcome the instability risk caused by multi-resonance, the phase margin compensator is added to the current loop to improve the robustness of the inverter to the grid impedance.