  Introducing more Distributed Generation (DG) into power grid infrastructure
drives more attention to understand how large scale DG affects grid operation.
Islanding is an important concern in this area. Islanding refers to the
condition that DGs within a microgrid continue energizing while the microgrid
has been disconnected from the main grid. Considering the adverse effects of
Islanding, it should be detected and managed in a proper way. After Islanding
has been detected, even though the first option is tripping all inverterbased
DG unit in the system, the system has this option to work as a stand-alone
microgrid. For achieving this goal, the frequency of microgrid should be
regulated. This paper proposes an islanding detection method based on current
detection in a parallel arm with the fuse arm of the microgrid. After islanding
detection, this paper presents an effective implementation Demand Response (DR)
to regulate the frequency in islanded microgrid as an Ancillary Service (AS)
considering the transient constraints of frequency in inverterbased
generations.
