Hitachi, Ltd.

Tomio Chiba

Mitsuyasu Kido

Junzo Kawakami

Tadao Kawai

Hiroshi Sasaki

Yoshio Sato

Kunio Hirasawa

Atsumi Watanabe

Hiroyuki Kudo

Yoshihiro Sano

Yoshiteru Miki

Yoshiaki Matsui

Hiroyuki Kudou

A power signal processing system and method for protection of a power system has a signal input unit for receiving a signal representing a condition of a power system; a plurality of processing units cooperating to apply to the received signal a predetermined process including a series of predetermined different computations thereby producing a control signal for controlling operation of the power signal processing system. The respective processing units operate to perform the predetermined different computations, respectively. A control unit is provided for controlling transfer of data among the processing units so that the different computations are applied, successively, to the received signal thereby producing the control signal which is used to cause, for example, the issue of a cut-off command to a circuit breaker.

Digital control and protection equipment for power system

In order to control a voltage using e.g. a tap transformer, the difference .DELTA.V between the actual voltage and a reference voltage is obtained and integrated over time. That integral is then modified by at least one parameter generated by fuzzy logic from control conditions of the voltage. In this way the fuzzy logic may find the optimum control strategy which keeps the actual voltage closest to the reference voltage without an excessive number of tap position changes. The reference voltage may vary with time, and therefore the control of the voltage with time may be evaluated, and the control conditions varied accordingly, e.g. by fuzzy logic, so that the control arrangement can exhibit learning. Normally, the integral is modified such that

Voltage or reactive power control method and control device therefor

Analog signals are sampled and converted into digital data which is then filtered by a digital filter. The filtered digital data is then subjected to an arithmetic operation. The blocking band of the digital filter is set to a frequency band which is above the pass band of the analog signal components. Frequency of sampling, as well as the frequency of noise caused by the sampling, is elevated, so that the noise frequency falls within the blocking band of the digital filter.

Digital signal processing method and system, electric power system

A disc is provided with the equal-interval pits along tracks, at which digital signals are recorded bit by bit. Such a disc is rotated at the constant angular velocity. A signal processing apparatus according to the present invention detects the linear velocity of the track which is at present followed by a pickup. The filtering of a source signal to be recorded and the analog-to-digital conversion of the filtered signal, in the signal processing for recording, are controlled and timed in accordance with the detected linear velocity. Further, the digital-to-analog conversion of a signal read out from the disc and the filtering of the converted signal, in the signal processing for reproducing, are also timed and controlled in response to the detected linear velocity. Thereby, a disc memory device having the large storage capacity and suited for the random access memory can be realized.

Signal processing apparatus for disc memory devices

A system for sampling and collecting simultaneously data from terminal apparatus installed at a plurality of data measuring locations (data sources) distributed in a system to be monitored or controlled by using at least a single optical fiber includes means for initiating sampling of measured quantities in response to a synchronizing signal supplied-from a master station, and means for allotting to the terminal apparatus respective particular time slots during which the data as measured is transmitted to the master station through at least a single optical fiber.

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Katsuta, Japan

Tomio Chiba