Patent ID: 7233082

Claim:
An interconnecting power generation system connected in parallel to a utility power system for supplying electrical power to an interconnecting load, comprising: an interconnecting inverter for linking generated electrical power to said utility power system; a voltage phase shift circuit which synchronizes the output voltage phase of said interconnecting inverter with the utility power voltage phase and monitors zero crossings of said utility power voltage, and which, when a predetermined number of zero crossings have been detected, to detect a power outage actively, shifts said output voltage phase from said utility power voltage phase during one cycle and shifts the shifted output voltage phase to said utility power voltage phase during the following cycle; a circuit breaker for shutting off the output of said interconnecting inverter from said utility power system; a phase comparator for comparing the voltage phase of said utility power system and said output voltage phase of said interconnecting inverter; and an interconnection control unit which detects a power outage caused by an interruption of power supply from said utility power system based on a series of a predetermined number of matching signals outputted from said phase comparator and sends a control signal to said circuit breaker to shut off the output of said interconnecting inverter from said utility power system.