Full-State Feedback Equivalent Controller for Active Damping in LCL-Filtered Grid-Connected Inverters Using a Reduced Number of Sensors

This paper presents a method for the active damping of a grid-tie LCL inverter. This method is based solely on the feedback of the injected current into the grid and is applicable to any linear current controller. It requires a low additional computational load over that required to control a grid-tie L inverter and the same measurements. A general design methodology for the current controller, which allows positioning all of the closed-loop poles of the system at arbitrary locations (even unstable modes of the LCL filter), is proposed. Stability and robustness of the resulting system are analyzed. Simulation and experimental results that validate the proposal are presented.