Combined active damping with adaptive current control for converters with LCL filters

This paper proposes a grid side current control technique for Pulse Width Modulated converters connected to the grid through LCL filters. The system is modeled in order to allow the implementation of a multi-loop control strategy. The inner loop is designed for active damping using the classical approach of feeding back the capacitor voltage or current to implement a Proportional plus Derivative or a Proportional controller, respectively. The outer loop is designed for the compensation of parametric uncertainties and disturbances by means of a Model Reference Adaptive Controller. The adaptive behavior allows to easily design the outer controller despite de presence of the inner one.