Harmonic Correction Method Based on Full Frequency Passive Reference Model

In weak grid environments, digital control delays degrade the stability of capacitor current feedback (CCF), thereby deteriorating the quality of grid-connected current. To enhance system robustness, this paper proposes a harmonic correction method based on a full frequency passive reference model. First, the underlying mechanisms of CCF performance degradation under inverter control delays are systematically analyzed. Then, leveraging passivity theory, a reference model with stable positive damping characteristics is constructed, and its stable components are employed to replace the unstable components in the actual system model. The proposed method effectively mitigates the impact of grid impedance variations on CCF stability. Finally, MATLAB/Simulink simulation results validate that the proposed scheme exhibits superior robustness compared with the traditional CCF method, ensuring reliable operation under challenging weak grid conditions.