Indirect Grid Current Control of LCL Filter based Grid-Connected Converter

This paper presents a method to indirectly control the grid current of a grid connected converter interfaced with a LCL filter. The proposed method is based on estimating the fundamental and harmonic components of the current drawn by the filter capacitor. The estimated fundamental and harmonic components of the filter capacitor current are then compensated by injecting an equal amount of current from the converter side using a well-designed current controller. This indirectly ensures the grid current to be at the desired power factor and immune to any distortions in the grid voltage. The proposed estimation and control scheme is verified by experimental results.