Hitachi, Ltd.

The Kansai Electric Power Co., Inc.

The Tokyo Electric Power Company, Incorporated

The Kansai Elect. Power

Haruo Nohara

Akio Ito

Akira Bando

Hiroto Nakagawa

Takayuki Matsuda

Eiji Haraguchi

Kenichi Ono

Masuo Goto

Yoshiji Nii

Osamu Sugimoto

Hiroshi Sugisaka

Hidenori Sawa

Tadaatsu Kato

Yoichi Yamazaki

Takao Kuwahara

A control system for controlling the load of an AC motor/generator of secondary AC excitation type connected to a power system in parallel to at least a synchronous machine. The AC motor/generator has the secondary excitation winding thereof controlled in the amount of excitation so as to generate an output in accordance with an external output command. In the case of variation of power flow between the power system and the synchronous machine, the output command is corrected in accordance with the variation, and the amount of the secondary excitation is controlled by the corrected output command, whereby the variation of power flow between the power system and the synchronous machine is absorbed by the AC motor/generator thereby to prevent the synchronous machine from stepping out.

Control system for AC motor/generator of secondary AC excitation type

A control system for variable speed hydraulic turbine generator apparatus comprises an induction generator connected at its primary side to an AC power line system, a secondary excitation controller connected to the secondary side of the induction generator and being responsive to a generator output command signal supplied externally to supply to the induction generator an excitation current which causes the induction generator to generate AC power at the same frequency as that on the AC power line system, a hydraulic turbine for rotating the induction generator, a guide valve for regulating the amount of water supplied to the hydraulic turbine, a rotation speed detector for detecting a rotation speed of the induction generator, a rotation speed command calculator for receiving a hydraulic turbine running condition signal inclusive of the external generator output command signal and calculating an optimum rotation speed command, a rotation speed controller for comparing the optimum rotation speed command with a rotation speed signal from the rotation speed detector and producing a guide valve opening control signal in accordance with a difference between the optimum rotation speed command and the rotation speed signal, and a guide valve driver responsive to the guide valve opening control signal to deliver to the guide valve a signal which controls the opening of the guide valve in accordance with the guide valve opening control signal.

Control system for variable speed hydraulic turbine generator apparatus

Provided is a digital fault-location calculation system which comprises first means for obtaining data including voltage and current information of a power transmission system subjected to fault-location calculation, a computer, and second means coupled between the first means and the computer for transferring the obtained data to the computer from the first means. The computer has at least two functions, one of which is the detection of occurrence of a faultin the transmission line and the other is the calculation of distance from the point of installation of the system to the fault point, in response to the data transferred through the second means and in accordance with predetermined processes. The distance to the fault point is computed by the other function of the computer only upon the detection of occurrence of a fault in the transmission line by the one function of the same.

Digital fault-location calculation system

Growing community of inventors

Hitachi, Japan

Haruo Nohara