Independent operation detection method, independent operation detection apparatus and distributed power supply system

摘要

PROBLEM TO BE SOLVED: To accurately detect a single operation of a distributed power source.SOLUTION: A single operation detection device includes a reactive power step injection section 54, a frequency feedback section 53 and a harmonic wave injection section 56. When separating an inverter section 41 that converts DC power supplied from a distributed power source 31 into AC power from a power system 32 to perform the single operation, if a step injection generation condition is satisfied, the reactive power step injection section 54 injects reactive power from the inverter section 41 to a power system side in a stepwise manner and rapidly changes a system frequency. The frequency feedback section 53 increases the injection of the reactive power in proportion to a rate of change of the system frequency and enlarges the change of the system frequency, such that the single operation is detected by generating abnormality in the system frequency. The harmonic wave injection section 56 injects a harmonic current to the power system side and changes a harmonic voltage during a power failure of the power system 32, such that the reactive power is injected while satisfying the step injection generation condition.