Design of Robust Power Control of a Three-phase Grid-Connected Inverter

This thesis describes a method of Linear Matrix Inequality (LMI) to determine robust gain for a three-phase grid-connected inverter (GCI). The robust controller technique is applied to a three-phase dc-ac inverter. This controller employs state feedback and integration of the tracking error in the 𝑑𝑞 rotational frame so that the offset-error can be eliminated. An LMI-based optimization scheme is used to determine stabilizing gains of the controllers so that the settling time to the steady-state is minimized under the presence of uncertainties in the L-filter. The uncertainties of the system express as the possible ranges of the resistance and inductance values. In addition, the implementation of switching states, IGBTs are switched by sinusoidal pulse width modulation (SPWM) technique.