Patent ID: 7701085

Claim:
A grid interconnection device connected to a power distribution system through which alternating-current power is transmitted and to a power supply device provided to a customer, the grid interconnection device comprising: a detector configured to detect a start of transmission of the alternating-current power based on a state of the alternating-current power; a receiver configured to receive a grid interconnection start instruction for starting grid interconnection between the power distribution system and the power supply device, through a predetermined transmission path a determination unit configured to judge that the power distribution system and the power supply device should be interconnected when the receiver receives the grid interconnection start instruction, after the detector detects a start of transmission of the alternating-current power, and a controller configured to control grid interconnection and power system separate of the power distribution system and the power supply device, in accordance with a result judged by the determination unit, wherein the controller starts grid interconnection between the power distribution system and the power supply device upon receipt of the grid interconnection start instruction in a state where the detector detects the start of transmission of the alternating-current power.