Individual operation prevention device null of

摘要

PROBLEM TO BE SOLVED: To isolate a distributed power supply from a system and surely prevent independent operation only in the customer side by detecting change of impedance or admittance, based on the prevention of power supply of the system. ;SOLUTION: An independent operation preventing apparatus is equipped with a current injecting apparatus 20 for injecting a current of intermediate order harmonics of a frequency lower than the frequency of the estimated lowest resonance order frequency in the power which is supplied of the system to the system from a leading line 13, a means for detecting direction and amount of capacitance and inductance in change of impedance or admittance about intermediate order harmonics in the system observed from the power receiving point A, and a means for detecting prevention of power supply from a change which exceeds a fixed value of the capacitive direction of impedance or admittance based on the detected result of this means.;COPYRIGHT: (C)1999,JPO