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.