Hitachi, Ltd.

The Tokyo Electric Power Company, Incorporated

Hiroyuki Kudo

Junzo Kawakami

Dai Watanabe

Chihiro Fukui

Yasushi Harada

Masahiko Amano

Hiroshi Inoue

Yasunori Katayama

Minoru Kanoi

Kiyoji Iwashita

Kazuo Nishijima

Hiroaki Ishikawa

Toru Takei

Yuzuru Imamura

Yoshiki Hirakouchi

Saburou Yasukawa

Hiroshi Sasaki

Kazuyoshi Yoshida

Mitsuyasu Kido

Atsumi Watanabe

Yoshihiro Sano

Tadao Kawai

Tomio Chiba

Kunio Matsuzawa

Keizo Inagaki

Yoshifumi Oura

An information processing system comprises a plurality of systems (1, 3, 4, 6) communicating through a transmission path (2) and performing a processing base on their own function. One of the plurality of systems acts as as an supervising system having a supervising function. The supervising system (1, 4) sets a goal for each of the plurality of systems, collects the processing result on each system and evaluates the processing result; and on the basis of the processing result, the supervising system sets a new goal for each system considering a goal of the entire system comprising said plurality of systems.

Information processing system

An electrical power distribution monitoring system is provided for a power distribution line having a plurality of sections with a plurality of electrical loads connected to the power distribution line to form a power distribution network. The monitoring system has at least one sensor for at least one present electrical value at least one point of the network, and estimates electrical values for at least one section of the line in dependence on both of present electrical values measured by the sensor and data relating to past power consumption by loads connected to the line. Improved prediction of actual conditions in the distribution line can be obtained.

Electrical power distribution monitoring system and method

An electrical power distribution monitoring system is provided for a power distribution line having a plurality of sections with a plurality of electrical loads connected to the power distribution line to form a power distribution network. The monitoring system has at least one sensor for at least one present electrical value at at least one point of the network, and estimates electrical values for at least one section of the line in dependence on both of present electrical values measured by the sensor and data relating to past power consumption by loads connected to the line. Improved prediction of actual conditions in the distribution line can be obtained.

Power distribution control system

An expert system in which a plurality of knowledge descriptive layers are provided in a frame system. Each descriptive layer is composed of several frames. The frames of the lower knowledge descriptive layer correspond to the elements of a knowledge processing object system. The content of frames of the upper knowledge descriptive layers is determined as an inference made with reference to the frames of the lower layer. This determination is initiated and executed when the content of slots of the frames is updated.

Expert system development support system and expert system environment

An expert system in which a plurality of knowledge descriptive layers are provided in a flame system. Each descriptive layer is composed of several flames. The flames of the lower knowledge descriptive layer correspond to the elements of a knowledge processing object system. The content of frames of the upper knowledge descriptive layers is determined as an inference made with reference to the frames of the lower layer. This determination is initiated and executed when the content of slots of the flames is updated.

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

In a transformer protection system, data of voltages and currents detected at individual terminals of a transformer connected to an electric power system are supplied to a computer. The computer computes driving point admittances or shunt admittances of the transformer on the basis of the voltage and current data and predetermined transfer admittances of the transformer and decides that an internal fault has occurred in the transformer when the values of the driving point admittances or shunt admittances deviate from pre-set reference values, thereby disconnecting the transformer from the electric power system.

Transformer protection system

A protective relay which hardly makes maloperation in itself regardless of mixing of low-order higher harmonics in its at least two sinusoidal input signals comprises a first and a second phase detection comparator generating two different-phase square signals indicative of the phase difference between the sinusoidal input signals, a first and a second timer receiving the square signals generated from the first and second phase detection comparators respectively and generating their output signals as a result of comparison between a first period of time and one of the periods or the period of presence or absence of the square signals, a third timer receiving the same square signal as that applied to the first timer and generating its output signal as a result of comparison between a second period of time and the other period or the period of absence or presence of the square signal, a fourth timer receiving the same square signal as that applied to the second timer and generating its output signal as a result of comparison between the second period of time and the other period or the period of absence or presence of the square signal, a first flip-flop set by the first timer and reset by the third timer, a second flip-flop set by the second timer and reset by the fourth timer, and a third flip-flop set and reset by an AND circuit and a NOR circuit respectively connected to the outputs of the first and second flip-flop.

Protective relay

Growing community of inventors

Hitachi, Japan

Hiroyuki Kudo