JP2012222964A - Fault detection method for protection relay device, and protection relay device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a fault of a protection relay device to be detected always accurately irrespective of whether there is a system voltage.SOLUTION: A protection relay device 105 includes first, second analog circuits 107, 108 which have the same constitution and are connected in parallel, and amplify and output a signal of predetermined frequency including a system signal related to the system voltage of an electric power system; a signal generation part 122 which generates a signal for inspection distinguishable from the system signal; and control means which inputs, on the basis of whether the system signal is input to the first, second analog circuits 107, 108, one of the system signal and signal for inspection to the first, second analog circuits 107, 108 to determine whether the first, second analog circuits get out of order, and reports that the device gets out of order if at least one of the first, second analog circuits gets out of order.

Description

  The present invention relates to a failure detection method for a protective relay device and a protective relay device.

Conventionally, digital protective relay devices have been used to detect power system accidents such as power line ground faults. The digital protection relay device has a failure detection function in order to detect its own failure.
The digital protection relay device detects an accident in the power system by amplifying the system voltage to a signal of a predetermined level or removing noise and outputting the signal, and digitally processing the signal from the analog circuit unit A digital processing unit is provided.
If the analog circuit unit fails, an abnormal malfunction may occur. Therefore, a function for detecting the presence or absence of a failure in the analog circuit section is provided as a constant monitoring function.

  As an example of the failure detection function of the digital protective relay device, the system voltage from the transmission line is input as a system signal via the input converter, and the system signal is used as the first analog circuit unit for fault detection and the failure. For detection, the signal is input to the digital processing circuit section through a second analog circuit section that is connected in parallel to the first analog circuit section and has the same configuration as the first analog circuit section. When the difference between the output signals of the first and second analog circuit units exceeds a predetermined value, the digital processing circuit unit determines that a failure has occurred in the analog circuit unit. Thereby, it becomes possible to detect a failure of the protective relay device.

By the way, in general, it is not often performed to stop the power generation of the generator, but in a plant or the like, the output of the generator is usually stopped. Therefore, the system voltage cannot be used when the generator stops generating power. In some cases, the system voltage cannot be used due to other causes such as an accident.
Since the above-described protective relay device uses a system voltage to detect a failure, there is a problem in that the failure of the protective relay device itself cannot be detected when the system voltage cannot be used.

As a solution to this problem, as described in Patent Documents 1 and 2, a method for detecting a failure of the protective relay device using a harmonic signal that is a predetermined number of times the system frequency (harmonic superposition monitoring method) A protective relay device having a failure detection function has been developed.
In the harmonic superposition monitoring method, a system signal corresponding to the system voltage and a separately generated harmonic signal for inspection (a frequency signal of a predetermined number of times of the system frequency) are superimposed on the analog circuit part of the protective relay device. input. The signal corresponding to the system voltage is removed by the filter circuit, and only the harmonic signal is extracted.

FIG. 2 is a characteristic diagram showing an example of the filter circuit, in which the system frequency is 50 Hz and the frequency of the harmonic signal for inspection is 200 Hz (fourth harmonic). In FIG. 2, the filter circuit has such a characteristic that a signal having a system frequency of 50H hardly passes but a harmonic signal of 200 Hz passes almost without being attenuated. The presence / absence of a failure in the analog circuit unit is detected based on the harmonic signal detected through the filter circuit.
In the harmonic superposition monitoring method, since the failure detection is performed using the harmonic signal, it is possible to constantly monitor the failure of the protective relay device regardless of the presence or absence of the system voltage.

However, since the harmonic signal for inspection is superimposed on the system signal, the system frequency may fluctuate when the generator output is unstable. In this case, the system signal passes through the filter circuit, and a frequency component equivalent to the harmonic signal for monitoring is extracted, so that there is a problem that it is difficult to accurately detect a failure.
Therefore, there is a problem that it is difficult to always accurately detect a failure of the protective relay device regardless of the presence or absence of generated power.

JP 2003-333742 A JP 2004-289975 A

  An object of the present invention is to make it possible to always detect a failure of a protective relay device accurately regardless of the presence or absence of a system voltage.

According to the first aspect of the present invention,
System signals related to the system voltage of the power system are input to the first and second analog circuits that are configured identically and connected in parallel to amplify and output a signal of a predetermined frequency,
Based on the output signal of at least one of the first and second analog circuits, it is determined whether or not the system signal is input to the first and second analog circuits,
When it is determined that the system signal is input to the first and second analog circuits, the first and second analog signals are output when the difference between the output signals of the first and second analog circuits is within a predetermined range. When the analog circuit is determined to be normal and the difference between the output signals of the first and second analog circuits is outside the predetermined range, at least one of the first and second analog circuits is determined to be faulty,
When it is determined that the system signal is not input to the first and second analog circuits, a test signal that can be distinguished from the system signal is input to the first and second analog circuits and within a predetermined range. The first and second analog circuits that output the above signal are determined to be normal, and the first and second analog circuits that are outputting the signal outside the predetermined range are determined to be faulty. A fault detection method for a protective relay device is provided.

According to the second aspect of the present invention,
First and second analog circuits configured to amplify and output a signal having a predetermined frequency including a system signal related to the system voltage of the power system, which are configured in parallel and connected in parallel.
Signal generating means for generating a test signal distinguishable from the system signal;
It is determined whether or not the system signal is input to the first and second analog circuits, and either the system signal or the inspection signal is input to the first or second analog circuit to input the first signal. 1. Control means for determining whether or not the second analog circuit is faulty and notifying that the device is faulty when at least one of the first and second analog circuits is faulty. A protective relay device is provided.

  According to the present invention, it is possible to always accurately detect a failure of the protective relay device regardless of the presence or absence of the system voltage.

It is a block diagram of a protection relay device concerning an embodiment of the invention. It is a characteristic view of the filter circuit used for the conventional protective relay device.

FIG. 1 is a block diagram of a protective relay device according to an embodiment of the present invention.
In FIG. 1, 101 is a generator, 102 is a power transmission line, 103 is a circuit breaker, and 105 is a protective relay device according to an embodiment of the present invention. The generator 101 may be a generator used in a plant or a generator for a general business operator or a general household as long as power generation and generation stop are switched. The frequency (system frequency) of the power generated by the generator 101 may be 50 Hz or 60 Hz, but is 50 Hz in the present embodiment.

  The protective relay device 105 includes an input converter 106, a first analog circuit 107, a second analog circuit 108, a digital processing unit 109, and a third filter circuit 115. The first and second analog circuits 107 and 108 are analog circuits that are targets of failure detection. The digital processing unit 109 is a digital circuit unit that determines whether or not the first and second analog circuits 107 and 108 are out of order and whether or not an accident has occurred in the power system and controls the interruption of power supply.

The input converter 106 steps down the power generation voltage (system voltage) of the generator 101 input via the power transmission line 102 to a predetermined level and outputs a signal (system signal) corresponding to the system voltage. The system signal is a signal representing the system voltage of the power system, and is a signal related to the system voltage.
The first analog circuit 107 is an analog circuit for detecting a power system accident such as a short circuit accident of the transmission line 102. The second analog circuit 108 provided in parallel with the first analog circuit 107 is an analog circuit provided for checking whether or not the analog circuit 107 has failed.

  The first analog circuit 107 includes a first amplifier circuit 116 including resistors R1, R2, and R3 and an amplifier A1, and a first filter circuit 117 including a capacitor C1 and an amplifier A2. The first amplifier circuit 116 amplifies the system signal from the input converter 106 to a level suitable for processing by the digital processing unit 109 and outputs the amplified signal. The first filter circuit 117 is a low-pass filter for removing high-frequency noise, and a cutoff frequency is determined so that a signal having a predetermined frequency including a system frequency and a test signal described later passes. In the present embodiment, the fourth harmonic signal of the system frequency (signal having a frequency of 200 Hz) is used as the inspection signal, and the cutoff frequency is 150 Hz.

The second analog circuit 108 has the same configuration as the first analog circuit 107 so as to have the same characteristics. That is, the second amplifier circuit 118 has the same configuration as the first amplifier circuit 116, and the second filter circuit 119 has the same configuration as the first filter circuit 117.
The output unit of the first analog circuit 107 is connected to the first input unit of the multiplexer 110 of the digital processing unit 109, and the output unit of the second analog circuit 108 is connected to the second input unit of the multiplexer 110. The output section of the third filter circuit 115 is connected to the third input section of the multiplexer 110 and is also connected to the input sections of the first analog circuit 107 and the second analog circuit 108.

The digital processing unit 109 includes a multiplexer 110, an analog / digital (A / D) converter 111, a control unit 112, an output unit 113, and a digital / analog (D / A) converter 114.
The multiplexer 110 selectively outputs analog signals from the first and second analog circuits 107 and 108 and the third filter circuit 115 to the A / D converter 111. The A / D converter 111 converts the analog signal from the multiplexer 110 into a digital signal and outputs it to the control unit 112. The control unit 112 performs processing to be described later on the output signal of the A / D converter 111.

  The control unit 112 includes a filter unit 120, a determination unit 121, and a signal generation unit 122 that generates a test signal in a digital format. The filter unit 120 passes the system frequency to the determination unit 121 but blocks the frequency of the inspection signal, and the filter unit 120 blocks the system frequency as in the filter shown in FIG. And a second filter unit 124 that passes through the determination unit 121. The control unit 112 can be configured by hardware, but can be configured by software using a central processing unit (CPU) and a program.

  The determination unit 121 receives the output signal of the A / D converter 111 via one of the first filter unit 123 and the second filter unit 124, or receives the signal in parallel in a time division manner via both. By performing a predetermined determination as will be described later with respect to the received signal, control to open / close the circuit breaker 103 by trip output of the output unit 113, control to cause the signal generation unit 122 to generate and stop the inspection signal, etc. Do.

  The inspection signal in the digital signal format from the signal generator 122 is converted into an analog signal by the D / A converter 114 and then input to the third filter circuit 115. The third filter circuit 115 is a low-pass filter including a capacitor C2 and an amplifier A3, and removes a high-frequency component (distortion component) included in the inspection signal input from the D / A converter 114, thereby obtaining a smooth sine The wave inspection signal is output to the input portions of the first and second analog circuits 107 and 108 and the third input portion of the multiplexer 110.

  The digital processing unit 109 constitutes a digital processing unit, the control unit 112 constitutes a control unit, the determination unit 121 constitutes a determination unit, and the signal generation unit 122 constitutes a signal generation unit. The filter unit 120 constitutes a filter unit, the first filter unit 123 constitutes a first filter unit, and the second filter unit 124 constitutes a second filter unit. The multiplexer 110 constitutes multiplexer means, the A / D converter 111 constitutes A / D conversion means, and the D / A converter 114 constitutes D / A conversion means.

The operation of the protective relay device 105 configured as described above will be described in detail below.
First, an operation when the protective relay device 105 detects an accident in the power system in a state where the generator 101 is generating power and an operation where the protective relay device 105 detects its own failure will be described.
The electric power generated by the generator 101 is transmitted to various devices (loads) arranged in the plant via the power transmission line 102 and the circuit breaker 103 that is closed in the normal state. The system voltage is input to the protective relay device 105 via the power transmission line 102.

  A system signal corresponding to the system voltage is input to the first and second analog circuits 107 and 108 via the input converter 106. Since the first and second analog circuits 107 and 108 have the same configuration, the output signals of the first and second analog circuits 107 and 108 are at the same level when they are normal. The output signals of the first and second analog circuits 107 and 108 are input to the first and second input sections of the multiplexer 110.

  The multiplexer 110 time-divides the output signal of the first analog circuit 107 input to the first input portion and the output signal of the second analog circuit 108 input to the second input portion in a predetermined cycle. Output in series alternately. The output signals of the first and second analog circuits output in series from the multiplexer 110 are converted into digital signals by the A / D converter 111 and input to the control unit 112.

  In the control unit 112, when the determination unit 121 receives the output signals of the first and second analog circuits 107 and 108 in the digital format via the first filter unit 123, the level of both the output signals is determined. When the first and second analog circuits 107 and 108 are normal, the levels of the two signals are the same, and even if variations such as design errors are taken into consideration, the level difference between the two signals is within a predetermined range. . Therefore, the determination unit 121 determines that the first and second analog circuits 107 and 108 are normal when the level difference between the two signals is within a predetermined range.

In addition, when a constant level signal is obtained as the output signal of the first analog circuit 107 at this time, that is, when the output signal of the first analog circuit 107 is within a predetermined range, a normal system voltage is obtained. Therefore, it is determined that no accident has occurred in the power system.
When an accident occurs in the power system, the system voltage input to the input converter 106 changes, and the output signal levels of the first and second analog circuits 107 and 108 become values outside the predetermined range. Also in this case, when the level difference between the output signals of the first and second analog circuits 107 and 108 is within a predetermined range, the determination unit 117 determines that the first and second analog circuits 107 and 108 are normal.
However, since the level of the output signal of the first analog circuit 107 is outside the predetermined range, it is determined that an accident has occurred in the power system, and a trip output is generated from the output unit 113 to open the circuit breaker 103. The power supply from the generator 101 to various loads is cut off.

  On the other hand, when one of the first and second analog circuits 107 and 108 fails, the levels of the output signals of the first and second analog circuits 107 and 108 are different from each other. When the difference between the output signals of the first and second analog circuits 107 and 108 input via the multiplexer 110 and the A / D converter 111 is outside the predetermined range, the determination unit 121 outputs the first and second analogs. It is determined that one of the circuits 107 and 108 has failed, and the output relay 113 notifies that the protective relay device itself is in failure (device failure output) so that quick recovery can be performed.

  It is unlikely that both the first and second analog circuits 107 and 108 will fail at the same time, and the level difference between the output signals of the first and second analog circuits is within the predetermined range. . Therefore, when the difference between the output signals of the first and second analog circuits 107 and 108 is within a predetermined range, it is normal. When the difference between the output signals is outside the predetermined range, one of the first and second analog circuits 107 and 108 has failed. If it is determined that at least one of the first and second analog circuits has failed, the protection device can be quickly recovered by outputting a device failure, and a major accident due to device malfunction or malfunction To prevent the situation from developing.

Next, an operation in which the protective relay device 105 detects its own failure in a state where the generator 101 stops power generation will be described.
In a state where the generator 101 stops generating power, a signal corresponding to the system voltage is not output from the input converter 106. Therefore, the output signals of both the first and second analog circuits 108 are below a predetermined level. Therefore, the signals input from the first and second analog circuits 107 and 108 to the control unit 112 via the multiplexer 110 and the A / D converter 111 each have a voltage equal to or lower than a predetermined value.

  When the determination unit 121 of the control unit 112 determines that the output signals of both the first and second analog circuits 107 and 108 obtained via the first filter unit 123 are equal to or lower than a predetermined value (in other words, the generator 101 If it is determined that the power generation has stopped, the signal generator 122 is caused to generate a test signal that is a signal for testing whether the analog circuits 107 and 108 are normal. The inspection signal may be any signal as long as it can be distinguished from the system voltage by the determination unit 121, but in this embodiment, a harmonic signal of the system frequency (in this embodiment, the first signal) 4 harmonic signal, ie 200 Hz signal).

The test signal output from the signal generator 122 is a digital signal, converted to an analog signal by the D / A converter 114, converted to a smooth analog signal by the third filter circuit 115, and then the first, The signals are inputted to the respective input parts of the second analog circuits 107 and 108 and the third input part of the multiplexer 110. The inspection signal output from the third filter circuit 115 is a smooth sine wave signal from which distortion components have been removed.
The inspection signals input to the first and second analog circuits 107 and 108 are input to the first and second input portions of the multiplexer 110 via the first and second analog circuits 107 and 108.

  The multiplexer 110 inputs the output signals of the first analog circuit 107, the second analog circuit 108, and the third filter circuit 115 input in parallel to the A / D converter 111 in series in a time-division manner in a predetermined cycle. . The A / D converter 111 converts the output signals of the first and second analog circuits 107 and 108 and the third filter circuit 115 sequentially input in series from the multiplexer 110 into digital signals and sequentially inputs them to the control unit 112. To do.

  The determination unit 121 of the control unit 112 is configured to detect the signal input to the third input unit of the multiplexer 110 via the second filter unit 124. By detecting a test signal (fourth harmonic signal) exceeding a predetermined level (a level sufficiently larger than the noise level) directly input to the third input unit via the second filter unit 124, a signal is obtained. It is determined that the inspection signal is supplied from the generation unit 122.

  When the determination unit 121 determines that the test signal is supplied, the first filter unit 123 and the second filter unit 123 detect the output signal of the first analog circuit 107 input to the first input unit of the multiplexer 110. The filter unit 124 is used by alternately switching at a predetermined cycle, and also when detecting the output signal of the second analog circuit 108 input to the second input unit of the multiplexer 110, the first filter unit 123 and the second filter The output signal of the A / D converter 111 is detected by alternately switching the units 124 at predetermined intervals.

  That is, the determination unit 121 switches the first filter unit 123 and the second filter unit 124 alternately with a predetermined period for the output signal of the first analog circuit 107 among the output signals of the A / D converter 111. A signal output from each of the first filter unit 123 and the second filter unit 124 is detected, and the first filter unit 123 and the second filter unit 124 are alternately switched at a predetermined cycle for the output signal of the second analog circuit 108. Thus, signals output from the first filter unit 123 and the second filter unit 124 are detected. The determination unit 121 detects the inspection signal input directly from the third filter circuit 115 to the multiplexer 110 via the second filter unit 124.

  The determination unit 121 detects that the test signal is directly input from the third filter circuit 115 to the multiplexer 110 based on the output signal of the A / D converter 111, and the first and second analogs If the levels of the inspection signals output from the circuits 107 and 108 are both within a predetermined range, both the first and second analog circuits 107 and 108 are determined to be normal.

On the other hand, the determination unit 121 detects that the test signal is directly input from the third filter circuit 115 to the multiplexer 110 based on the output signal of the A / D converter 111, 2 When at least one of the inspection signals output from the analog circuits 107 and 108 has a voltage level outside the predetermined range, the first analog circuit 107 or the second analog circuit 107 that outputs the inspection signal at a level outside the predetermined range. It is determined that the analog circuit 108 has failed.
In this way, it is possible to detect whether or not the first and second analog circuits 107 and 108 have failed.

If the determination unit 121 determines that at least one of the first and second analog circuits 107 and 108 has failed, the relay protection device 105 can be quickly recovered by outputting a device failure from the output unit 113. This prevents a situation where the protective relay device 105 itself malfunctions and develops into a major accident due to malfunction.

When the generator 101 resumes power generation from the power generation stop state, a signal having a system frequency corresponding to the system voltage is output from the first and second analog circuits 107 and 108. Output signals of the first and second analog circuits 107 and 108 are input to the first and second filter units 123 and 124 via the multiplexer 110 and the A / D converter 111.
As described above, the determination unit 121 detects the output signals of the first and second analog circuits 107 and 108 while alternately switching the first and second filter units 123 and 124 at a predetermined period. Therefore, the determination unit 121 detects the system frequency signal output from the first and second analog circuits 107 and 108 via the first filter unit 123.

When the determination unit 121 determines that the output signals of the first and second analog circuits 107 and 108 are within a predetermined range, the signal generation unit 122 stops generating the inspection signal, and the first and second Control is performed so that only the filter unit 123 is used for the output signal determination of the analog circuits 107 and 108. Thereby, as described above, the fault detection of the power system and the failure detection of the protective relay device 105 when the system voltage is generated are performed.
As described above, it is possible to always detect the failure of the protective relay device 105 regardless of whether or not the generator 101 is generating power, that is, whether or not the system voltage exists. .

The failure detection method of the protective relay device according to the embodiment of the present invention,
A system signal related to the system voltage of the power system is input to the first and second analog circuits 107 and 108 that are configured identically and connected in parallel to amplify and output a signal of a predetermined frequency,
Based on the output signal of at least one of the first and second analog circuits 107 and 108, it is determined whether or not the system signal is input to the first and second analog circuits 107 and 108,
When it is determined that the system signal is input to the first and second analog circuits 107 and 108, the first signal is output when the difference between the output signals of the first and second analog circuits 107 and 108 is within a predetermined range. When the difference between the output signals of the first and second analog circuits 107 and 108 is out of the predetermined range while determining that the second analog circuits 107 and 108 are normal, at least one of the first and second analog circuits 107 and 108 is detected. Is determined to be malfunctioning,
When it is determined that the system signal is not input to the first and second analog circuits 107 and 108, a test signal that can be distinguished from the system signal is input to the first and second analog circuits 107 and 108. The first and second analog circuits 107 and 108 that output signals within a predetermined range are determined to be normal, and the first and second analog circuits 107 and 108 that output signals outside the predetermined range are out of order. It is comprised so that it may determine.
Here, when the output signal of the first analog circuit 107 is out of a predetermined range (in other words, when the output signal indicates that an accident has occurred in the power system), the power supplied from the power system to the load is cut off. Can be configured to.
Therefore, it is possible to always detect a failure of the protective relay device 105 regardless of whether or not the generator 101 is generating power, that is, whether or not a system voltage exists.

Further, the protective relay device 105 according to the embodiment of the present invention includes:
First and second analog circuits 107 and 108 that are configured identically and connected in parallel to amplify and output a signal of a predetermined frequency including a system signal related to the system voltage of the power system,
A signal generator 122 for generating a test signal distinguishable from the system signal;
It is determined whether the system signal is input to the first and second analog circuits 107 and 108, and either the system signal or the test signal is input to the first and second analog circuits 107 and 108. Then, it is determined whether or not the first and second analog circuits 107 and 108 are in failure, and if at least one of the first and second analog circuits 107 and 108 is in failure, the device is notified of the failure. And a control means.

Here, the control means includes
When it is determined that the system signal is input to the first and second analog circuits 107 and 108, the first signal is output when the difference between the output signals of the first and second analog circuits 107 and 108 is within a predetermined range. When the second analog circuits 107 and 108 are determined to be normal and the difference between the output signals of the first and second analog circuits 107 and 108 is outside the predetermined range, at least one of the first and second analog circuits 107 and 108 is detected. Is determined to be malfunctioning,
When it is determined that the system signal is not input to the first and second analog circuits 107 and 108, the inspection signal is supplied to the first and second analog circuits 107 and 108, and signals within a predetermined range are supplied. The first and second analog circuits 107 and 108 that output a signal are determined to be normal, and the first and second analog circuits 107 and 108 that output a signal outside the predetermined range are determined to be faulty. can do.

  Further, when the control means determines that the system signal is input to the first and second analog circuits 107 and 108, an accident occurs in the power system using the output signal of the first analog circuit 107. When it is determined whether or not an accident has occurred, the power supply from the power system to the load can be cut off.

Further, the first and second analog circuits 107 and 108 are each configured to amplify and pass a signal having a predetermined frequency including the system frequency of the power system,
The inspection signal is a harmonic signal of a predetermined multiple of the system frequency,
The control means includes
When a signal exceeding a predetermined voltage is output from at least one of the first and second analog circuits 107 and 108, the difference between the output signals of the first and second analog circuits 107 and 108 is within a predetermined range. When the circuit breaker provided between the power system and the load is maintained in a closed state and the difference between the output signals of the first and second analog circuits 107 and 108 is out of a predetermined range, it is notified that the device is faulty.
If no signal exceeding a predetermined voltage is output from any of the first and second analog circuits 107 and 108, the test signal is input to the first and second analog circuits 107 and 108, and the first When the output signals of both the second analog circuits 107 and 108 are within a predetermined range, the circuit breaker is maintained in a closed state, and at least one of the output signals of the first and second analog circuits 107 and 108 is out of the predetermined range. In this case, it can be configured to notify that the apparatus is out of order.

Therefore, it becomes possible to always detect the failure of the protective relay device 105 accurately regardless of the presence or absence of the system voltage.
In the present embodiment, an example in which two analog circuits 107 and 108 are used as analog circuits has been described.

  The present invention can be applied to a protective relay device that detects an accident of an overhead power transmission line or an underground power transmission line and a failure detection method of the protective relay device.

DESCRIPTION OF SYMBOLS 101 ... Generator 102 ... Power transmission line 103 ... Circuit breaker 105 ... Protection relay device 106 ... Input converter 107 ... 1st analog circuit 108 ... 2nd analog circuit 109 ... Digital processing unit 110 ... Multiplexer 111 ... A / D converter 112 ... Control unit 113 ... Output unit 114 ... D / A converter 115 ... Third filter circuit 116 ... first amplifier circuit 117 ... first filter circuit 118 ... second amplifier circuit 119 ... second filter circuit 120 ... filter unit 121 ... determination unit 122 ... signal generation unit 123 ... 1st filter part 124 ... 2nd filter part R1, R2, R3 ... Resistance A1, A2, A3 ... Amplifier C1, C2 ... Capacitor

Claims (6)

System signals related to the system voltage of the power system are input to the first and second analog circuits that are configured identically and connected in parallel to amplify and output a signal of a predetermined frequency,
Based on the output signal of at least one of the first and second analog circuits, it is determined whether or not the system signal is input to the first and second analog circuits,
When it is determined that the system signal is input to the first and second analog circuits, the first and second analog signals are output when the difference between the output signals of the first and second analog circuits is within a predetermined range. When the analog circuit is determined to be normal and the difference between the output signals of the first and second analog circuits is outside the predetermined range, at least one of the first and second analog circuits is determined to be faulty,
When it is determined that the system signal is not input to the first and second analog circuits, a test signal that can be distinguished from the system signal is input to the first and second analog circuits and within a predetermined range. The first and second analog circuits that output the above signal are determined to be normal, and the first and second analog circuits that are outputting the signal outside the predetermined range are determined to be faulty. Failure detection method for protective relay device.   2. The failure detection method for a protective relay device according to claim 1, wherein when the output signal of the first analog circuit is outside a predetermined range, the power supplied from the power system to the load is cut off. First and second analog circuits configured to amplify and output a signal having a predetermined frequency including a system signal related to the system voltage of the power system, which are configured in parallel and connected in parallel.
Signal generating means for generating a test signal distinguishable from the system signal;
It is determined whether or not the system signal is input to the first and second analog circuits, and either the system signal or the inspection signal is input to the first or second analog circuit to input the first signal. 1. Control means for determining whether or not the second analog circuit is malfunctioning and notifying that the apparatus is malfunctioning when at least one of the first and second analog circuits is malfunctioning. Protective relay device characterized by. The control means includes
When it is determined that the system signal is input to the first and second analog circuits, the first and second analog signals are output when the difference between the output signals of the first and second analog circuits is within a predetermined range. When the analog circuit is determined to be normal and the difference between the output signals of the first and second analog circuits is outside the predetermined range, at least one of the first and second analog circuits is determined to be faulty,
When it is determined that the system signal is not input to the first and second analog circuits, the inspection signal is supplied to the first and second analog circuits, and a signal within a predetermined range is output. 4. The protection relay according to claim 3, wherein the first and second analog circuits that are determined to be normal and the first and second analog circuits that output signals outside a predetermined range are determined to be faulty. Electrical equipment.   The control means determines whether an accident has occurred in the power system using the output signal of the first analog circuit when it is determined that the system signal is input to the first and second analog circuits. 5. The protective relay device according to claim 3, wherein, when it is determined that an accident has occurred, power supply from the power system to the load is cut off. Each of the first and second analog circuits is configured identically so as to amplify and pass a signal having a predetermined frequency including the system frequency of the power system,
The inspection signal is a harmonic signal of a predetermined multiple of the system frequency,
The control means includes
When a signal exceeding a predetermined voltage is output from at least one of the first and second analog circuits, and the difference between the output signals of the first and second analog circuits is within a predetermined range, the power system and the load The circuit breaker provided in between is maintained in a closed state and when the difference between the output signals of the first and second analog circuits is outside a predetermined range, a notification is made that the device is faulty,
When a signal exceeding a predetermined voltage is not output from any of the first and second analog circuits, the test signal is input to the first and second analog circuits, and the first and second analog circuits are input. When the output signals of both analog circuits are within a predetermined range, the circuit breaker is maintained in a closed state, and when at least one of the output signals of the first and second analog circuits is out of the predetermined range, the device is faulty. The protective relay device according to any one of claims 3 to 5, wherein the protection relay device is notified.

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