This chapter develops a droop-based robust distributed cooperative control scheme for AC microgrids under a switching communication network with non-uniform time varying delays. This chapter illustrates a pinning-based frequency/voltage controllers containing a distributed voltage observer. In addition, a consensus-based active/reactive controllers are applied into the distributed intelligent cooperative protocol to generate the nominal set points used in the primary control stage for distributed energy resources. By employing these approaches, the frequency and weighted average DER agents’ voltage can be pinned to a given value and power sharing of active and reactive power is maintained. Finally, by considering the non-uniform delay in the communication network between distributed DER agents, this chapter proves the sufficient conditions of network connectivity and delay upper bound to ensure the reliability and stability of microgrids.