Patent ID: 7745956

Claim:
A grid interconnection device including a power conversion circuit for converting power from a power generation device into predetermined alternating-power, and connecting the power generation device to a power distribution system through the power conversion circuit and a relay, comprising: a relay controller configured to control separation or interconnection of the relay; a receiver configured to receive, from a predetermined transmission path, power failure information containing at least local area information indicating an area in which a power failure occurs; a determination unit configured to determine an occurrence of a power failure in the power distribution system, when the power failure information includes local area information of an area to which the power distribution system belongs; and a detector configured to detect an islanding state, wherein the detector increases detection sensitivity of the islanding state when the determination unit determines the power failure occurs in the power distribution system, and the relay controller performs separation control for the relay when the islanding state is detected by the detector.