A RC with High Robustness against Grid Impedance Variation

The inject grid current of the grid-connected inverter will worsen under grid voltage distortion, Conventional Phase Lead Compensation Repetitive Controller (CPLC-RC) is a feasible method for harmonic suppression, but this scheme will be instable under weak grid. To overcome these drawbacks, an Improved Phase Lead Compensation Repetitive Controller (IPLC-RC) is proposed, which achieves higher robustness against grid impedance variation. Compared to CPLC-RC, the proposed scheme only introduces an extra low pass filter, which achieves the system stability under the weak grid. When the proposed scheme is adopted under the weak grid, the inject grid current is still sinusoidal under strong grid voltage distortion. Experimental results verify the feasibility of the IPLC-RC.