Alternating converting the systematic run type manner of dispersed power system, and the direct current

摘要

PROBLEM TO BE SOLVED: To provide a system cooperation method with which an islanding phenomenon of a distributed power source can securely be detected even if a load phase is delayed or advanced and to provide a system cooperation inverter.;SOLUTION: A control part 3 is provided with a target current setting part 17 creating an output current target value of active current, a phase fluctuation part 18 which alternately fluctuates the phase to an advance phase and a delay phase at a constant period and a modulation part 19 outputting AC current having periodical reactive power fluctuation to a cooperation point. The phase fluctuation part 18 is provided with a first frequency determination part 24 determining whether an output frequency is out of a prescribed first frequency range or not. When the output frequency is out of the first frequency range, reactive power is fixed in the phase at that time. While it is fixed, the modulation part 19 stops a modulation operation when the frequency deviates from a second frequency range which is set wider than the first frequency range.;COPYRIGHT: (C)2006,JPO&NCIPI