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

Claim 0:
1. 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, in order to synchronize 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, the power conversion device matches a frequency of the power supplied from the power conversion device to the load with a frequency of the power from the commercial power supply, and
after the matching between the frequencies of the powers, the power conversion device matches a zero crossing point of the power supplied from the power conversion device to the load with a zero crossing point of the power from the commercial power supply.