Although the primary droop control can maintain the voltage and frequency stable when the microgrid switches to islanded mode,it leads to the voltage and frequency deviations of each DG. A distributed cooperative secondary control of microgrids was applied to restore the voltage and frequency to their references and achieve power sharing. The microgrids could be considered as multi- agent systems since each DG was an agent and the communication network was modelled by a digraph. Considering the limitation o...