Kabushiki Kaisha Toshiba

The Tokyo Electric Power Company, Incorporated

Yasuchika Nishitani

Akira Ishibashi

Mamoru Suzuki

Takafumi Maeda

Ken Yanagihashi

A power system protection system prevents a voltage drop resulting from the reactive power characteristic of a power system. A main device for acquiring a system electric quantity of one or a plurality of upper substations detects a voltage drop resulting from the reactive power characteristic of the power system and transmits a detection signal of the voltage drop to a terminal device for acquiring a system electric quantity of one or a plurality of lower substations. Each terminal device sequentially sheds loads starting from those suffering more from the influence of the voltage drop resulting from the reactive power characteristic based on the load voltage and load current of a load bus.

Power system protection system

A digital protective relay apparatus comprising an analog input section, a correction value-calculating section, a storage section, a correction section, a protective calculation section. A correction value for correcting the error of the analog input section is predetermined and stored in the storage section. Digital data obtained through the analog input circuit is corrected by the correction section using the correction value. The protective calculation section performs predetermined calculation using the corrected digital data, thereby determining whether or not a trip instruction should be supplied to a breaker.

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Tokyo, Japan

Yasuchika Nishitani