A Unified Distributed Control for Grid-connected and Islanded Modes in Multi-Bus AC Microgrid

This paper proposes a novel universal control for multi-bus AC microgrid with the capability to operate in both grid-connected (GC) and islanded (IS) modes. The control scheme is based on distributed manner, and the leader-follower consensus protocol is designed. Only few leader distributed generators (DGs) receive the correction signals from the unified mode controller, which is installed at the point of common coupling (PCC). The rest follower DGs would track the leader DGs, and exchange information with their neighbors. Under this control framework, the active and reactive power can be flexibly controlled to inject into the grid in GC mode. Meanwhile, the voltage/frequency support and active/reactive power sharing are guaranteed in IS mode. Moreover, the proposed method is able to offer seamless transition between GC and IS modes. Finally, simulations are presented to verify the satisfied transition process of different modes.