New control strategy for grid-connected inverter using LCL filter

This paper presents a new approach that provides scaling the LCL-filter inductances based on the harmonic analysis of the filter output current. The approach considers the filter design together with the inverter control, both together, improving the system stability and the dynamic response. The model and general guidelines for selecting the filter parameters, taking into account the variation of the grid equivalent inductor and the use of non-linear inductances, are presented. The proposed control system makes use of feed-forward control in order to increase performances of the feedback control and eliminates the need of synchronization procedure. Simulation tests with a 15 kW three-phase VSI with a LCL filter have proved the effectiveness of the proposed approach.