System deployment and decentralized control of islanded AC microgrids without communication facility

This paper proposes a novel system deployment principle for master/slave type islanded alternating current (AC) microgrids, with which decentralized control can be achieved without communications. The net power of a microgrid, including active and reactive power, is metered and compensated locally and independently by its units. This can benefit a microgrid regarding system expandability, flexibility, and plug-and-play. The proposed strategy is demonstrated in a typical islanded AC microgrid with diesel generators, renewable generation, and hybrid storage. A diesel generator set with constant speed governor and static exciter runs to build up and dominate the main AC bus. An ultra-capacitor unit suppresses fast-varying power fluctuations, and the battery shares part of the slow-varying power component. The diesel generator set only provides slow-varying power within a lower limit, which can avoid dramatic accelerations and decelerations and low load-rate operation. Finally, simulations on MATLAB/Simulink are carried out to verify the proposed strategy in typical scenarios.