Output feedback control of three-phase grid-tied inverter with LCL filter with enhanced transient response

This paper presents a robust feedback controller for three-phase grid-tied inverter using LCL filter. Specifically, the feedback controller is designed to mitigate the effect of the resonance frequency associated with LCL filter with a view to ensure a stable and accurate control of the current injected to the grid. In renewable energy conversion systems (RECSs), the grid current regulation is required to either adjust the DC-link voltage or control the power exchange between the grid and the renewable energy sources. The current controller is designed based on the stationary coordinates to cope with both balanced and unbalanced grid voltages. An existing output feedback control was slightly modified to cope with control input saturation. The performance of the proposed controller was verified by simulation tests. The developed feedback controller showed a significant ability to reject sinusoidal disturbances and to asymptotically track the sinusoidal current reference with improved transient response during control saturation.