µ-synthesis control for an islanded microgrid with structured uncertainties

Abstract

This paper presents a robust control scheme for an islanded microgrid in the presence of structured uncertainties. The microgrid consists of parallel connection of two Distributed Generation (DG) units and a passive load. The DG units are connected to the passive load by using the power electronics converters. The microgrid model is structurally uncertain due to the large perturbations in the load parameters. To deal with the uncertainties, a Linear Fractional Representation (LFR) of the parametrically uncertain system is obtained. To achieve robust performance, the μ-synthesis approach is applied to the derived LFR model to design a μ controller. The resultant controller is structurally simple and satisfies the mixed sensitivity constrains imposed by weighting functions in the prescribed range of parameter perturbations. Furthermore, a robust stability analysis of the proposed controller is carried out in this paper. Simulation case studies performed in MATLAB/SimPowerSystems software confirm the effectiveness of the proposed control system.