The Tokyo Electric Power Company, Incorporated

Kabushiki Kaisha Toshiba

Hitachi, Ltd.

Mitsubishi Denki Kabushiki Kaisha

Takafumi Maeda

Akira Ishibashi

Mamoru Suzuki

Mitsuru Yamaura

Fumio Andow

Yasuhiro Kurosawa

Yoshihiro Sano

Yoshiaki Matsui

Yasuchika Nishitani

Keizo Inagaki

Hiroshi Yamakawa

Ken Yanagihashi

Setsurou Mine

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

Protective relay system provided with difference and addition filters

A method and system of transformer protection in which parallel admittance currents indicative of the apparent excitation state of a transformer to be protected are evaluated from the transformer terminal voltages and currents sampled at a proper interval, and discrimination between an internal defect and excitation inrush is made in response to a magnitude of the parallel admittance current, and a breaker opening command is issued in response to a judgement of internal defect. The method and system enables high-accuracy and high-sensitivity fault detection through a simple computation.

Method and system of transformer protection and method and system of

A static reactive-power compensating apparatus in which transients having a frequency below a predetermined frequency are not compensated for while all other variations are fully compensated for. A reset filter circuit is connected between the output of a rectifier circuit and a thyristor control circuit, the latter controlling the firing of thyristors which couple a reactive energy storage bank to the power system for compensating for voltage variations in the system. Preferably, the reset filter has a transfer characteristic of sT.sub.1 /(1+sT.sub.1).

Static reactive-power compensation apparatus

Growing community of inventors

Tokyo, Japan

Takafumi Maeda