The Tokyo Electric Power Company, Incorporated

Kabushiki Kaisha Meidensha

Jun Motohashi

Takaaki Kai

Kouji Kondou

Nobuhiro Kuroda

Chikashi Nakazawa

Yoshiyuki Hirayama

Haruo Sasaki

Toshiaki Fujimoto

Yasutomo Imai

Hirotoshi Kaneda

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.

Single or isolated operation detecting apparatus for a distributed power

A method for detecting islanding operation of a rotating-machine type dispersed generator. The dispersed generator is interconnected with a main electric source through a circuit breaker to constitute an electric power system. The estimating method is implemented as follows: (a) changing electric power of the electric power system; (b) detecting frequency component of the electric power; and (c) deciding that an islanding operation of the dispersed generator is executed if the change of the frequency component becomes greater than a predetermined value. With this method, it becomes possible to detect the islanding operation of the dispersed generator even if the power flow at the interconnecting circuit breaker is generally zero.

Method and apparatus for detecting islanding operation of dispersed

Growing community of inventors

Kawasaki, Japan

Jun Motohashi