| 摘要 |
PURPOSE: To hold a power conversion unit in a self-supported operation at a failure in power system and return to a system interconnection operation at restoration, by switching the control of an inverter circuit into a current control circuit at the power failure and into a voltage control circuit after the restoration. CONSTITUTION: In a distribution power supply system, a voltage control circuit 8 is added to a current control circuit 7. During operation of system interconnection with power distribution system, an inverter 3 is controlled by using the current control circuit 7. Then, a control changing switch 9 is switched by an interconnection protection unit 11 to control the inverter 3 by the voltage control circuit 8 during the self-supported operation. When the interconnection protection unit 11 judges a failure that arises in power distribution system from a detection signal fed by a system condition detector 12, the control on the inverter circuit 3 is switched from the voltage control circuit 8 to the current control circuit 7, and the current control circuit 7 is changed to the voltage control circuit 8 when the power system is restored. As a result, a self-supported operation is kept under an abnormal condition, and the self-supported operation is changed into system interconnection operation at its restoration. |
