Ellipsoidal-Set Design of the Decentralized Plug and Play Control for Direct Current Microgrids

Recently the integration of renewable energy resources to direct-current microgrids has become a hot research topic. The voltage stability problem is of paramount importance when the system is subject to external disturbances, parameters uncertainties, and plug-and-play regimes. This paper introduces a novel decentralized voltage tracking for a direct-current islanded microgrid. It consists of numerous Distributed Generation units. The decentralized controller of each distributed generator adjusts the voltage at the point of common coupling to track the desired reference. The proposed control copes with the plug-and-play operation of the microgrid. This means that the possibility of connection/disconnection distributed generators without deteriorating the stability of the overall microgrid is done through the invariant ellipsoid set and the linear matrix inequality optimization. Another merit of the proposed control is that updating the rest of the controllers is not required when a distributed generator is plugged in or out. Moreover, the proposed decentralized controller just uses local states (information) of its distributed generator only. Many simulations and practical studies with different scenarios have been conducted in this paper to verify the performance of the proposed controllers. Comparison with the existing schemes is included.