A Control Method of Inverter used for Distributed Power Supply under Voltage Sag Condition

Abstract

Inverter which is used for distributed power supply, such as solar cell or fuel cell system, tends to stop easily by voltage sag. In the present electric power system, there is little problem by this characteristic of inverter. But if the number of those inverters connected to power system increases, the quality of system voltage and frequency may deteriorate by stop of the inverters. In addition, about fuel cell system, its output power cannot be controlled quickly, and the whole system may stop by a rise of inside temperature.
For these problems, we tried to realize high continuous operation ability of inverter used for distributed power supply under voltage sag condition. This paper shows a control method of inverter for the over current caused by sudden change or unbalance of the system voltage and examination results with 3-phase 200V-4kW class inverter system.