Single or isolated operation detecting apparatus for a distributed power supply

摘要

The invention is directed to an apparatus for detecting if a distributed power supply is switched from cooperation with another power system to isolated or single operation. The distributed power supply includes a synchronous generator and possibly also another power source such as an induction generator. The single operation detecting apparatus includes a frequency detector connected to a line system of a customer, reactive power regulating equipment connected to the distributed power supply, a fluctuation signal generator for providing periodic small fluctuations to a reactive power setter of the reactive power regulating equipment, and a single operation signal generator for monitoring the output of the frequency detector to output a single operation signal when the monitored output deviates from a range between allowable upper and lower limits around a reference frequency. It is possible to detect the isolated or single operation mode by actively disturbing the balance between the energy generated by the distributed power supply and the power consumed by the distributed power supply, when the distributed power supply disconnected from the cooperation with power system.