Fuzzy scheduling of robust controllers for islanded DC microgrids applications

In the present paper a decentralized control scheme that relies on sliding mode (SM) and high gain control methodologies to regulate the load voltage in buck-based islanded direct current (DC) microgrids is designed. First, the model of a buck-based islanded DC microgrid consisting of several Distributed Generation units interconnected through an arbitrary complex and meshed topology including rings is introduced. More precisely, the topology of the power network is represented by its corresponding incidence matrix, and in the model the power lines dynamics is considered. Moreover, it is assumed that the microgrid is affected by unknown load demand and unavoidable modelling uncertainties. A mixed strategy, employing both a third-order sliding mode (3-SM) control algorithm and a high gain control strategy, with a fuzzy scheduling is designed to solve the voltage control problem in a decentralized manner. Specifically, the high-gain control reduces the stress on the generator during abrupt reference changes, the 3-SM guarantees finite-time voltage regulation and strong robustness with respect to load variations. Fuzzy scheduling merges the two strategies. Finally, detailed simulation results confirm the effectiveness of the proposed control strategy.