Discrete-Time Robust Control of a Microgrid System with Parameter Variations

Microgrids are increasingly implemented in power systems due to their advantages resulting from the integration of renewable energy sources. Voltage source converters used in these systems require improved control methods when the parameters of the system change. This paper presents a robust control method for the voltage source converter connected in a microgrid in discrete-time system model by using the linear quadratic regulator method. Discrete-time robust stability bounds based on the Lyapunov stability and time-invariant methods are presented to ensure the stability of the converter based microgrid system if parameter variations occur. These robust stability measures are used to design robust controller in discrete-time for the microgrid system. The eigenvalues of the closed-loop system designed by using the linear quadratic regulator, with perturbations that meet the stability conditions, have absolute values less than one making the system stable. The MATLAB implementation of the proposed discrete-time robust control method for microgrid system provided good results by giving stable initial condition responses for the closed-loop system with perturbations.