Patent ID: 11916389
Assignee: DAIHEN CORPORATION
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H  B  Y | IPC B  H

Claim 4:
5. A grid interconnection system for a power grid, comprising:
a storage battery;
a power conversion device that converts power from the storage battery into AC; and
an interconnection control device that supplies power from a commercial power supply to a load and supplies power from the power conversion device to the load when the commercial power supply fails,
wherein, when the commercial power supply is restored, the interconnection control device starts supply of power from the commercial power supply to the load, and stops supply of power from the power conversion device to the load after the supply of power from the commercial power supply to the load is started,
wherein, when the commercial power supply is restored, the power conversion device synchronizes a voltage phase of power supplied from the power conversion device to the load with a voltage phase of power from the commercial power supply, and
after the voltage phase of the power supplied from the power conversion device to the load is synchronized with the voltage phase of the power from the commercial power supply, the interconnection control device starts supply of power from the commercial power supply to the load,
wherein, the power conversion device determines whether or not a voltage and a frequency of the power from the commercial power supply are within a predetermined range,
when the voltage and the frequency are within the predetermined range, the power conversion device synchronizes the voltage phase of the power supplied from the power conversion device to the load with the voltage phase of the power from the commercial power supply, and
when the voltage or the frequency is not within the predetermined range, the power conversion device waits for a process for phase synchronization and continues supply of power to the load.