| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that a protector of a power conversion device generally includes a function for protecting the power conversion device per se by opening a circuit breaker connected between the power conversion device and an AC system to stop operation of the power conversion device if overcurrent of an arm is detected, but if only one arm is short-circuited, a DC current flows to a side of the AC system, the current cannot be stopped and the circuit breaker cannot be safely opened.SOLUTION: The protector is configured to first disconnect another power conversion device being connected via a DC system from the AC system after the arm overcurrent is detected, and then disconnects the power conversion device of the protector's own from the AC system after the lapse of a time interval. Otherwise, after the arm overcurrent is detected, voltage output of all unit converters are substantially turned to 0 [V] and after all arms are substantially vertically short-circuited, the power conversion device is disconnected from the AC system. |
