Tokyo Shibaura Denki Kabushiki Kaisha

Kabushiki Kaisha Toshiba

Tokyo Denryoku Kabushiki Kaisha

Tokyo Denryoki Kabushiki Kaisha

Chugoku Denryoku Kabushiki Kaisha

Fumio Andow

Mitsuru Yamaura

Tetsuo Matsushima

Eiichi Okamoto

Ryotaro Kondow

Noriyoshi Suga

Minoru Iwasaki

Junichi Inagaki

Yuji Okita

Yasuhiro Kurosawa

Yoshiji Nii

Takafumi Maeda

Norio Fujisawa

Takayuki Kobayashi

Kyotaro Kondow

Masuo Nakashima

Minoru Kitagawa

Hiroshi Yamakawa

Protective relay system provided with difference and addition filters

In differential function calculation processing, a value of differential function f(d) is calculated using differences between a plurality of predetermined number p of differential current data Dd sampled at different sampling times. The differential current data is data obtained from differential current Id or a sum of data Dj (j=1 to n where n is the number of the respective terminal currents) obtained from respective terminal currents Ipj. In restraint data calculation processing, restraint data Dr is calculated using respective terminal current data Dj sampled at the same sampling time. In restraint function calculation processing, a value of restraint function f(r) is calculated using differences between a plurality of predetermined number p of restraint data Dr sampled at different sampling times. Then, in comparison processing, the value of differential function f(d) is compared with the value of restraint function f(r). If the value of differential function f(d) is smaller than a value, modified by a predetermined relationship, of restraint function f(r), an inhibit output is generated in the comparison processing. Differential relay processing inhibits a trip operation of a circuit breaker by the inhibit output from the comparison processing. The differential relay processing is so controlled as to execute the trip operation when the inhibit output is not present.

Digital calculation type differential relay

According to the present invention, a sampled value of a reference voltage V.sub.p which is a voltage (in general, a relative voltage to ground, an interphase voltage or a positive sequence voltage) prior to the occurrence of a fault in an electric-power system and a sampled value of the quantity of electricity E (a voltage or current in each phase or a symmetrical component voltage or current) during a fault time period or after the recovery of a fault are used to compute a plurality of functional values capable of specifying the phase angle .theta. or the value of .theta. of said quantity of electricity E in relation to said reference voltage V.sub.p and deliver them as information data. When the relative phase angle between the quantity of electricity E during a fault or after the recovery of a fault and a voltage (reference voltage) V.sub.p prior to the occurrence of a fault is clarified in this manner, the relative phase angles of reference voltages V.sub.p among a plurality of electric stations prior to the occurrence of a fault are computed by obtaining the information of normal operating conditions of the electric power system concerning to a voltage, current, reactive power and the state of a circuit breaker and accomplishing the arithmetic operations of the information thus obtained and the constants of devices and equipment constituting the electric-power system. Therefore, the relative phase angles of the quantity of electricity E among a plurality of electric stations during a fault period or after the recovery of a fault can be clarified.

Information data output device for electric-power systems

In an apparatus for producing data concerning a fault in an AC electric power system, an AC electric quantity is sampled at a frequency which is a multiple of the rated frequency of the AC electric quantity, and is stored, for later use as predicted values, and an arithmetic operation is performed on the sample values to produce a data concerning a fault in the power system. The predicted values are determined by the following equation: ##EQU1## where l and m represent natural numbers;

Protective control method and apparatus

A protective relaying system in which the electric stations at both ends of a district of a power system to be protected optically transmit and receive reciprocally the information of the electric stations. A first protective relay device responds to both the electrical quantities from the opposite side terminal and electrical quantities of its own side terminal, and a second protective relay device responds only to the electrical quantities of its own side terminal. The respective protective relay devices are controlled by virtue of error detection circuits and signal discontinuity detection circuits connected to the optical transmission line to thereby discriminating the mere failure in the optical transmission line from the concurrent failures in both the optical transmission line and the transmission line so as to rapidly eliminate the failures.

Protective relaying system

A protective relay system for protecting a power system includes a selection circuit, a comparing circuit, and a data processing unit. The selection circuit time-sequentially switches a plurality of input signals having electrical quantities from the power system under control of the data processing unit and applies the input signals to the comparing circuit. The comparing circuit applies to the data processing unit a discriminated output signal representing the result of the comparing of a level of a signal having an electrical quantity and obtained from the input signals to the comparing circuit with a reference level. At a time point upon lapse of a time corresponding to an electrical angle of 90.degree. of the input signal, for example, after the logical level of a first discriminated output signal corresponding to a first controlled state of the selection circuit has been changed, the comparing circuit produces a second discriminated output signal corresponding to a second controlled state of the selection circuit different from the first controlled state. The data processing unit determines the level of a protection output signal according to a logical level of the second discriminated output signal.

Protective relay system

A protective relaying system which detects a fault in an electric power system having a circuit breaker by using a current and a voltage of the electric power system. The protective relaying system includes input conversion unit adapted for connecting the electric power system to receive a first and a second input signals corresponding to the current and the voltage and for converting the magnitude and/or the phase of the first and second input signals to produce a first, a second and a third electrical quantities. The protective relaying system also includes comparing unit connected to receive the first, second and third electrical quantities, for comparing the first and second electrical quantities to produce a first logical state signal, and comparing the third and a fourth electrical quantities to produce a second logical state signal cyclically, and for producing a logical state signal including the first and second logical state signals cyclically. The protective relaying system further includes digital data processing unit connected to receive cyclically the logical state signal, for producing a first and a second serial logical state signals and for judging whether a phase-rotation sequence of the first and second serial logical state signals equals a predetermined sequence to produce a protection relay output signal. The protection relay output signal is used to trip the circuit breaker.

A protective relaying system is disclosed which detects a fault in an electric power system having a circuit breaker by using a current and a voltage of the electric power system. The protective relaying system includes an input conversion/unit adapted to receive a first and a second input signals corresponding to said current and voltage, for converting the magnitude and/or the phase of the first and second input signals to produce least two electrical quantities a first electrical quantity and a third electrical quantity, and for outputting the second input signal without conversion as a second electrical quantity. The protective relaying system also includes a comparing unit connected to receive first, second and third electrical quantities from the input conversion unit for comparing the first and second electrical quantities to produce a first logical state and comparing the third and fourth electrical quantities to produce a second logical state signal cyclically. The protective relaying system further includes a digital data processing unit for judging whether a specified logical condition between the first and second logical state signals holds for a predetermined number of times corresponding to a predetermined electrical angle, and for producing a protection relay output signal based on the judging result. The protection relay output signal is adapted for using to trip the circuit breaker.

When the positive-phase voltage of one terminal of a transmission line involved in a fault detected by a positive-phase relay exceeds a predetermined value, an output is supplied to the reclosing instructing device from an AND circuit to first reclose this terminal. When it is less than the predetermined value, this terminal is reclosed only if reclosing of the other terminals have been successfully completed.

Reclosing device for transmission line

In a digital protective relaying device for protecting electric power transmission line including an electric station at each end thereof, and each electric station including at least one circuit breaker to be tripped by a protective relay for protecting the own station, a digital protective relay provided with a computer is further provided at each end so as to receive electrical data in digital form from the electric stations for operating in an ordinary protective operation. As a control condition occurs in one station, the condition is sent to a digital protective relay provided at the other end of the transmission line, thereby changing the operational steps of the computer included in the protective relay.

Digital protective relaying systems

A relay device is disclosed which protects and controls an electric power line by detecting an electrical quantity carried by the electric power line. The relay device includes a rectifying circuit connected to the electric power line. The output of the rectifying circuit is supplied to a peak value holding circuit which stores the peak value of the output of the rectifying device during each predetermined period under control of a resetting pulse. The output of the peak value holding circuit is supplied to a detecting circuit having a predetermined threshold level.

Relay device

Monitor system for a digital signal

In a digital distance relaying system the principle of comparing the amplitude values of alternating current quantities is used. In one example, amplitude values of V and V-IZ are compared and in the other example the amplitude values of V-IZ and IZ are compared for determining the operating point of the relay system.

Distance relaying systems

The amplitude value of a sinusoidal wave is calculated by operating means which processes absolute values of two data samples which are sampled from the sinusoidal wave at two points spaced 90.degree. electrical degrees apart thereby producing an electrical signal proportional to the amplitude value. The operation means comprises a comparator, a combination of an adder and a subtractor, or a combination of a comparator and an adder. The output of the comparator or the combination is multiplied with a predetermined coefficient and then added together to produce said signal.

Apparatus for calculating amplitude values

The apparatus comprises a sampling hold circuit for sampling the amplitude of a sinusoidal wave at a predetermined frequency, a data sample extracting circuit for extracting two data samples at two points immediately before and after the peak value of the sinusoidal wave, and an operation circuit responsive to the absolute values of the two data samples for calculating the amplitude value of the sinusoidal wave.

Growing community of inventors

Hachioji, Japan

Fumio Andow