Digital Notch Filter Design for Grid Side Current Control of LCL-Filtered Grid-Connected Converter

This paper presents the design of an LCL-filtered three-phase grid-connected voltage source converter (VSC) with the object of interfacing electrochemical energy storage batteries to the grid. The effects of resonant poles of the LCL filter have been compensated by the cascade introduction of a notch filter that performs active damping. The adopted solution enables the usage of higher switching frequency, overcoming the stability constraints and improving the effectiveness of LCL filters. The proposed configuration has been designed and experimentally validated on a scaled prototype in different operative conditions. Furthermore, a harmonic current compensator integration has been investigated to enhance the robustness of the proposed VSC to grid voltage harmonic pollution.