Robust H-infinity Guaranteed Cost Controller Design for Islanded Microgrids: An LMI Approach

Abstract

This study proposes a guaranteed cost controller design for the secondary frequency control of islanded microgrids considering the modeling uncertainty of the distributed generators. To minimize the influence of the fluctuation of the generation from renewable energy sources such as photovoltaic (PV) and wind turbine (WT) generators, the H-infinity control method is integrated with a guaranteed cost control scheme. Specifically, a linear matrix inequality (LMI)-based controller design method to guarantee a certain level of the linear quadratic cost and L-2 gain from the disturbances to the grid frequency. A proportional and integral observer is incorporated with the designed state-feedback H-infinity guaranteed cost controller to estimate both the states of the system and external disturbances accurately. The numerical simulation result demonstrates the effectiveness of the proposed method.