Sinusoidal compensator with active damping effects in grid-connected inverter with an LCL filter

A voltage source inverter with an LCL filter is often used for a utility interface to control its output current to a grid side because of its harmonic reduction advantages. However it has a structure which accompanies LC resonant oscillations. Many active damping methods have been proposed. This paper proposes a digital sinusoidal compensator which has good active damping effects and a fast sinusoidal response with no delay. Compensator and feedback gains of the inverter are determined simply by the optimal control method. The proposed method is investigated and validated for the damping effects by simulation and experiment.