Decentralised Droopless Control of Islanded Radial AC Microgrids Without Explicit Communication

A microgrid is a proven effective way to integrate renewable resources. This study presents an innovative control concept for decentralized AC microgrids, which is based on the architectural advantage of a radial microgrid structure. Under the proposed concept, power sharing between the distributed sources is achieved without droop control. Thus the need for a secondary control level is eliminated. Moreover, the use of explicit communication is replaced in the paper by a novel coordination mechanism based on the locally measured currents. The paper shows that, with a special design of the current control of grid-feeding converters, the proposed microgrid automatically provides equitable sharing of the load demand amongst the distributed generators (DGs). Moreover, the dynamic responses of the DGs are identical and decoupled from one another. It is further shown that the proposed AC microgrid is stable in the presence of any type of load. The findings of the paper are validated by simulations and laboratory experiments.