Robust observer based active damping control for LCL filtered grid connected converters using LMI criterion

The design of current controller of voltage source converter connected to the grid through an LCL filter becomes more and more challenging because of the LCL filter resonance behaviour and the uncertainty of the grid impedance value which may lead to instability problems. In this context, a robust active damping control for LCL filtered grid connected inverter under grid inductance variation is proposed in this paper. The two useful methodologies, Lyapunov stability theory and LMI approach, are adopted to design robust observer-based control for this class of uncertain systems. The simulations results are given to illustrate the effectiveness of this control. A comparison study of the results derived in this work with previous observer based active damping method shows the superiority of the proposed design strategy.