Power Decoupling Strategy for Single-Phase Grid-Connected Inverter Under Weak Power Grid

This study analyzes the power coupling in a weak power grid, and designs a novel decoupling method for the power with multi harmonic frequency on the dc bus. By modifying the reference values of dc series split-capacitors, the system control structure can be simplified, and the multi-frequency-coupled power decoupling can be realized. Moreover, a notch filter is introduced into the dc voltage feedback path for further reducing the influence of the power coupling on the inverter output current quality. The proposed method can achieve the objective of the multi-frequency-coupled power decoupling, even under a weak power-grid environment. Finally, numerical simulations are provided to verify the effectiveness of the proposed method.