Abstract: A protective relay system detects a first electric variable and a second electric variable of a power system to discriminate in a time series whether or not a fault portion of a line or equipment included in the power system exists within a predetermined range, so as to determine whether protection of the power system should be carried out. The system includes a digital filter for outputting a first difference electric variable data indicative of a difference between at least two sample data of plural sampling data of the first electric variable and a difference between at least two sample data of plural sample data of the second electric variable at plural sampling times of the time series. The system also includes an addition filter for outputting first and second additive electric variable data indicative of orthogonal vector data with respect to the first and second difference electric variable data.

Abstract: 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).

Abstract: 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.

Abstract: 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;n represents a natural number;Y.sub.m represents the predicted value for a specific time point;S.sub.o represents a sample value in advance of the specific time point by m/2 times the rated period;S.sub.l represents a value equal to (-1).sup.l times the sample value at a time point in advance of the specific time point by l/2 times the rated period; andK.sub.o and K.sub.l represent constants satisfying the following relationship: ##EQU2## where .epsilon.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A monitor system comprising:an adder for summing up a plurality of unknown analog electric quantity signals denoting the operating conditions of such as a transmission line;a multiplexer for generating output signals corresponding to the plural analog electric quantity signals and also to a signal denoting the result of addition made by said adder;an A-D converter for converting output analog signals from the multiplexer into digital signals; anda monitor which sums up those of the output digital signals from the A-D converter which correspond to said plural analog electric quantity signals, compares a signal denoting the result of said addition with a digital signal converted from an output signal from the adder, receives an error detection signal denoting the known prescribed electric quantity converted into a digital signal through the multiplexer and A-D converter, and judges the operating condition of the A-D converter from the contents of said received digital signal.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: In a protective relaying system wherein a carrier wave frequency modulated by an electric quantity is transmitted to a receiving station for operating a relay and an abnormal condition of the transmitted signal is detected by detecting the frequency variation of the carrier wave, there is provided an abnormal condition detector which compares the lengths of contiguous or closely adjacent periods, or functions thereof, of the received carrier wave.

Abstract: In a static protective relay device utilizing a converter including a bandpass filter which causes time delay during transients, there are provided a detector responsive to the output from the converter, and means for preventing misoperation of the detector due to an attenuating oscillation of the output caused by the transient phenomenon of the converter which occurs during attenuation of the output.