  In this paper we propose a new decentralized control scheme for Islanded
microGrids (ImGs) composed by the interconnection of Distributed Generation
Units (DGUs). Local controllers regulate voltage and frequency at the Point of
Common Coupling (PCC) of each DGU and they are able to guarantee stability of
the overall ImG. The control design procedure is decentralized, since, besides
two global scalar quantities, the synthesis of a local controller uses only
information on the corresponding DGU and lines connected to it. Most important,
our design procedure enables Plug-and-Play (PnP) operations: when a DGU is
plugged in or out, only DGUs physically connected to it have to retune their
local controllers. We study the performance of the proposed controllers
simulating different scenarios in MatLab/Simulink and using performance indexes
proposed in IEEE standards.
