GRID-CONNECTED INVERTER SYSTEM HAVING SEAMLESS SWITCHING

摘要

A grid-connected inverter system having a seamless switching function. An inverter converts DC power into AC power. A breaker is connected between the inverter, a grid, and a load to switch between a grid-connected operation and an independent operation. A filter converts an output of the inverter into a sine wave. A controller operates the inverter in a current control mode or a voltage control mode. The controller operates the inverter in the current control mode for a period of time longer than a turn-off time of the breaker when an abnormality in the grid is detected, and operates the inverter in the voltage control mode when the grid is disconnected from the load due to turn-off of the breaker.