JP2001028829A - Digital protection relay - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the operating efficiency of a system by taking a digital signal with the amount of electricity being discriminated by a discrimination means for calculating a frequency, and by providing a monitor control means for locking the output of a monitor means when the frequency exists out of the range of an allowable frequency. SOLUTION: An analog input circuit 7 is composed of an analog filter for eliminating noise, a multiplexer, and an A/D converter for converting a sampled signal to digital. A relay body 17 performs operation processing required for system protection to a digital signal with the amount of input electricity, and protection output is inputted into a logic circuit 18 consisting of an inhibit circuit. The signal being outputted from a logic circuit 16 of a monitoring device 1 is inputted to a negative input terminal, and an output signal to a trip circuit is locked when a monitor failure signal is outputted, thus improving the operating efficiency of a system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital protection relay device for inputting an electric quantity of an electric power system through an analog input circuit to determine whether or not an accident has occurred in the electric power system. The present invention relates to a digital protection relay device provided with a monitoring device.

[0002]

2. Description of the Related Art Conventionally, there are various types of protective relays for protecting a power system, but recently, a so-called digital type protective relay that protects the power system using a digital processing unit such as a microcomputer. Electric devices are often used.

In this digital protection relay, after an A / D conversion of an electric quantity input from a system to an analog input circuit at a predetermined sampling frequency, the digital signal is taken into an arithmetic processing unit to protect the system. It performs necessary arithmetic processing. Since this type of technique is already known, a detailed description thereof will be omitted here.

Incidentally, such a digital protection relay device is provided with a monitoring device for detecting the presence or absence of a failure in an analog input circuit. This monitoring device superimposes a monitoring signal having a frequency higher than the sampling frequency on a digital signal obtained by A / D conversion of an electric quantity input to an analog input circuit, and converts the signal from the analog input circuit into a waveform discriminator. To discriminate a monitoring signal from a digital signal, and detect a change in the monitoring signal, thereby detecting a failure of the analog input circuit.

[0005]

However, in such a conventional monitoring device, when the frequency of the electric quantity input to the analog input circuit fluctuates, the fluctuation of the frequency is converted into a monitoring signal discriminated by the waveform discriminator. In some cases, even if there is no defect in the analog input circuit, it is determined that the analog input circuit is defective and the protection system is locked unnecessarily.
For this reason, there was a possibility that the operation rate of the protection relay device was reduced.

The present invention has been made in view of the above circumstances, and locks the output from a monitoring device against the output of an unnecessary monitoring failure signal caused by a factor other than the failure of an analog input circuit. It is an object of the present invention to provide a digital protection relay capable of improving the operation rate of a system.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a digital protection relay having a monitoring device of the following means.

According to a first aspect of the present invention, there is provided a digital protection relay having a monitoring device for inputting an electric quantity having a predetermined fundamental frequency and monitoring an analog input circuit for A / D conversion at a predetermined sampling frequency. In the apparatus, the monitoring device includes a superimposing unit that superimposes a known monitoring signal on an input electric quantity, and discriminates a signal after the composite signal superimposed by the superimposing unit is A / D converted by the analog input circuit. Discriminating means, a monitoring means for judging the presence or absence of a defect in the analog input circuit based on whether the monitoring digital signal discriminated by the discriminating means is equal to or higher than a predetermined monitoring level, and discriminated by the discriminating means. A digital signal of an electric quantity is taken and its frequency is measured, and when this frequency is out of the range of an allowable frequency, a monitor for locking the output of the monitoring means. Composed of a control means.

According to a second aspect of the present invention, in the digital protection relay device according to the first aspect of the present invention, the monitoring and controlling means is provided when the frequency of the digital signal of the electric quantity is out of the allowable frequency range. It has a function of locking the output of the monitoring failure signal by lowering the monitoring level of the monitoring means.

According to a third aspect of the present invention, an electric quantity having a predetermined fundamental frequency is input, and an analog input circuit of a main detection relay and an analog input circuit of an accident detection relay for performing A / D conversion at a predetermined sampling frequency are respectively monitored. In the digital protection relay device having a monitoring device, the monitoring devices of the main detection relay and the accident detection relay are superimposing means for superimposing a known monitoring signal on the input electric quantity, and a synthesizing device superimposed by the superimposing means. Discriminating means for discriminating a signal after the signal has been A / D-converted by the analog input circuit; and determining whether the monitoring digital signal discriminated by the discriminating means is at or above a predetermined monitoring level. Monitoring means for determining the presence / absence of a defect, and any one of the main detection relay and the accident detection relay Provided supervisory control means for locking the outputs of the monitoring unit with the monitoring device of the both relay and monitoring failure signal is input from the monitoring means with the monitoring device of the both relay.

According to a fourth aspect of the present invention, in the digital protection relay according to the third aspect of the present invention, the monitoring control means provided in one of the main detection relay and the accident detection relay is provided. Has a function of locking the output of the monitoring failure signal by lowering the monitoring level of the monitoring means of the monitoring device of the quantity relay when the monitoring failure signal is input from the monitoring means of the monitoring device of both relays .

According to a fifth aspect of the present invention, in the digital protection relay device according to the first aspect of the present invention, the monitoring control means receives a system condition signal such as switching of a circuit breaker or a switch. And a function of locking the output of the monitoring means for a certain time.

According to a sixth aspect of the present invention, in the digital protection relay device according to the first aspect of the present invention, the monitoring control means receives a system condition signal such as switching of a circuit breaker or a switch. And a function of lowering the defect detection sensitivity of the monitoring digital signal in the monitoring means for a certain time.

According to a seventh aspect of the present invention, in the digital protection relay device according to the first aspect of the present invention, the monitoring and control means determines the number of the plurality of analog input channels in which a defect is detected. It has a function of estimating the presence or absence of a defect or a part, and outputs a monitoring failure signal from the monitoring means only when it is estimated that the defect is present.

According to an eighth aspect of the present invention, in the digital protection relay device according to the first aspect of the present invention, the monitoring control means monitors a specific one of the plurality of analog input channels. It has a function of estimating the presence or absence of a defect or a part under the condition of detecting a defect and determining the cause thereof, and locks a monitoring failure signal output from the monitoring means when there is a failure other than the analog input channel. Things.

According to a ninth aspect of the present invention, in the digital protection relay device according to the first aspect of the present invention, the monitoring control means monitors a specific channel associated with the analog input channel among the plurality of analog input channels. It has a function of estimating the presence or absence of a defect or a part under the condition of detecting a defect and determining the cause thereof, and locks a monitoring failure signal output from the monitoring means when there is a failure other than the analog input channel. Things.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a monitoring device of an analog input circuit in a first embodiment of a digital protection relay according to the present invention.

In FIG. 1, reference numeral 1 denotes a monitoring device to which electric current and voltage are input from a current transformer 3 and a transformer 4 provided in a system 2.

The monitoring device 1 includes a monitoring signal generator 5
A superimposing circuit 6 for superimposing a monitoring signal of a predetermined frequency generated by the monitoring signal generator 5 on an input electric quantity from the system 2, and an analog input to which the signal superimposed by the superimposing circuit 6 is input. A circuit 7 and a digital signal 8 converted by the analog input circuit 7 are inputted, and a waveform discriminating circuit 10 for discriminating the digital signal 8 into a digital signal 12 of an input electric quantity from a system and a digital signal 11 of a monitoring signal. And the digital signal 11 of the monitoring signal separated by the waveform discrimination circuit 10 is input to the analog input circuit 7.
A monitoring circuit 13 that outputs a monitoring failure signal 14 when a failure is detected, and a digital signal 12 of an input electric quantity separated by the waveform discrimination circuit 10 are input, and the frequency of the system 2 is measured and the frequency falls within an allowable range. The monitoring control circuit 15 outputs a lock signal when the signal exceeds the threshold, and a logic circuit 16 locks a monitoring failure signal of the monitoring circuit 13 when the lock signal is output from the monitoring control circuit 15. In this case, as the logic circuit 16, an inhibit circuit that inputs a lock signal output from the monitoring control circuit 15 to the negative input terminal and locks a monitoring failure signal output from the monitoring circuit 13 is used.

Here, the analog input circuit 7 includes an analog filter for removing noise included in the input electric quantity of the system, a multiplexer for sampling the input electric quantity at a predetermined sampling frequency, and a digital conversion of a signal sampled by the multiplexer. A /
It is composed of a D converter.

On the other hand, reference numeral 17 denotes a relay main body to which the digital signal of the input electric quantity separated by the waveform discriminating circuit 10 is inputted. The relay main body 17 performs the arithmetic processing necessary for the system protection of the digital signal of the input electric quantity. The protection output is input to a logic circuit 18 composed of an inhibit circuit, and a signal output from the logic circuit 16 of the monitoring device 1 is input to a negative input terminal. Output signal is locked.

Next, the operation of the monitoring device for the analog input circuit in the digital protection relay device configured as described above will be described.

In the monitoring device 1, when the electric quantity of the current and voltage of the system 2 is input to the superposition circuit 6, the superposition circuit 6 converts the electric quantity input from the system into a predetermined value generated from the monitoring signal generator 5. The frequency monitoring signal is superimposed and input to an analog input circuit 7 including an analog filter, a multiplexer, and an A / D converter. The analog input circuit 7 converts the electric quantity on which the monitoring signal is superimposed into a digital signal at a predetermined sampling frequency, and supplies the digital signal to the waveform discriminating circuit 10.

The waveform discrimination circuit 10 discriminates the digital signal 8 input from the analog input circuit 7 into a digital signal 12 of an electric quantity input from the system and a digital signal 11 of a monitoring signal. The digital signal 11 of the monitoring signal separated by the waveform classification circuit 10 is supplied to the monitoring circuit 13, and the digital signal 12 of the input electric quantity is input to the monitoring control circuit 15.

The monitoring circuit 13 obtains the effective value of the digital signal 11 of the monitoring signal, and determines whether or not the analog input circuit 7 is defective based on whether the effective value is equal to or higher than a predetermined monitoring level. When it is determined that there is no failure, the monitoring failure signal 14 is not output, and when it is determined that there is a failure, the monitoring failure signal 14 is output.

In this case, even if the analog input circuit 7 has no defect, if the frequency of the system 2 fluctuates, the effective value obtained above fluctuates and becomes higher than a predetermined monitoring level. 14 may be output.

On the other hand, the monitoring control circuit 15 calculates the frequency of the system 2 based on the digital signal 12 of the input electric quantity, and determines whether or not the frequency exceeds the allowable frequency range.
When it is determined that the value exceeds the allowable range, a lock signal is output.

Therefore, even if the effective value fluctuates due to the fluctuation of the system frequency and the monitoring failure signal 14 is output from the monitoring circuit 13, the lock signal is output from the monitoring control circuit 15, so that the logic circuit 16 outputs the lock signal to the alarm circuit. The monitoring failure signal is blocked. At this time, since the output of the logic circuit 16 is also input to the negative terminal of the logic circuit 18 on the relay main body side, unless the protection output is output from the relay main body 17, an output signal by the monitoring failure signal is output to the trip circuit. It will not be.

In the above-mentioned supervisory control circuit, there are many digital operation methods for calculating the system frequency. As an example, the method described in Electric Joint Research, Vol. 50, No. 1, Second Generation Digital Relay, page 68, can be applied. .

As described above, according to the first embodiment, the monitoring control circuit 15 is added, and when it is determined that the frequency of the input electric quantity exceeds the allowable frequency range, the monitoring signal is output from the monitoring circuit by the lock signal. Since the monitoring failure signal to be monitored is locked, it is possible to prevent the failure of the analog input circuit 7 and the output of the monitoring device 1 caused by unnecessary failure detection due to the frequency fluctuation of the system 2.

FIG. 3 is a block diagram showing a monitoring device for an analog input circuit according to a second embodiment of the digital protection relay device according to the present invention. Are omitted, and different parts will be described here.

In the second embodiment, as shown in FIG. 2, the monitoring control circuit 15-1 uses the digital signal 12 of the input electric quantity supplied from the waveform discrimination circuit 10 to control the system 2.
Is measured, and it is determined whether or not the frequency is out of the allowable frequency range. If the frequency is out of the allowable frequency range, a level switching command of a logical value “1” is given to the monitoring circuit 13-1 to detect a defect. The sensitivity is lowered, and when it is not deviated, a level switching command of a logical value "0" is given to the monitoring circuit 13-1.

As shown in FIG. 3, defect detection sensitivities (detection levels) K1 and K2 are set for the monitoring circuit 13-1, and the digital signal of the monitoring signal exceeds the K1 detection level and the K2 detection level. Level determination circuits 13a and 13b that output the monitoring failure signal 14 only when the
Inhibit circuit 13c provided on the input side of level determination circuit 13a for detection level K1, and AND circuit 1 provided on the input side of level determination circuit 13b for detection level K2
3d, an OR circuit 13e provided on the output side of each of the level determination circuits 13a and 13b.
The switching command is input from the monitoring control circuit 15-1 to the negative input terminal of the negative input terminal 3c, the digital signal 11 of the monitoring signal is input to the input terminal, and the monitoring control circuit is input to the AND circuit 13d. The switching command and the digital signal 11 of the monitoring signal are input from 15-1.

Next, the operation of the monitoring device for the analog input circuit in the digital protection relay device configured as described above will be described. The digital signal 8 input from the analog input circuit 7 by the waveform classification circuit 10 is input from the system. Digital signal 12 of electric quantity and digital signal 11 of monitoring signal
The operation until the digital signal 11 of the monitoring signal is input to the monitoring circuit 13-1 and the digital signal 12 of the input electric quantity is input to the monitoring control circuit 15-1 is the same as that of the first embodiment. .

The monitoring circuit 13-1 determines the effective value of the digital signal 11 of the monitoring signal, and determines whether or not the analog input circuit 7 is defective by determining whether the effective value is equal to or higher than a predetermined monitoring level. When it is determined that there is a failure, the monitoring failure signal 14 is output.

In this case, even if there is no defect in the analog input circuit 7, when the frequency of the system 2 fluctuates, the effective value obtained above fluctuates and becomes higher than a predetermined monitoring level. There is a possibility that the failure signal 14 is output.

At this time, the supervisory control circuit 15 calculates the frequency of the system 2 based on the digital signal 12 of the input electric quantity, determines whether or not the frequency exceeds the allowable frequency range. If it is determined that the state of the monitoring circuit 13 has been changed, the switching instruction of the logical value "1" is given to the monitoring circuit 13 to lower the detection level of the monitoring circuit 13-1.

That is, in FIG. 3, the analog input circuit 7
However, there is a case where the effective value of the digital signal of the monitoring signal becomes higher than the detection level, here the K1 detection level of the level determination circuit 13a, due to the fluctuation of the system frequency. However, at this time, the monitoring control circuit 15-1
The switching instruction of the logical value "1" is given by the inhibit circuit 13c.
And the input to the AND circuit 13d, the effective value of the digital signal of the monitoring signal is taken into the K2 detection level switching circuit 13b switched from the K1 detection level switching circuit 13a.

Therefore, the detection sensitivity of the monitoring circuit 13-1 is K
Since the detection level is lowered by switching from the 1 detection level to the K2 detection level, the monitoring failure signal is not output from the monitoring circuit 13-1 to an alarm circuit (not shown).
At this time, since the logical value “0” is input to the negative terminal of the logic circuit 18 on the relay main unit side, the relay main unit 1
As long as the protection output is not output from 7, the output signal due to the monitoring failure signal is not output to the trip circuit.

In the monitoring control circuit 15, the above-mentioned method can be applied as a digital operation method for calculating the system frequency.

As described above, according to the second embodiment, the monitoring control circuit 15-1 is added to the monitoring circuit 1 when it is determined that the frequency of the input electric quantity exceeds the range of the allowable frequency.
Since a switching command is given to 3-1 to lower the defect detection sensitivity of the monitoring circuit 13-1, the analog input circuit 7
Monitoring device 1 due to frequency fluctuation of system 2
Output due to unnecessary defect detection can be prevented.

In the second embodiment, the case where the level determination circuits 13a and 13b having different detection levels are provided as means for lowering the defect detection sensitivity of the monitoring circuit 13-1 has been described. 1 stores a plurality of detection levels having different level values in advance, and when it is determined that the frequency of the input electric quantity exceeds the allowable frequency range, the detection level is transferred to the monitoring circuit 13-1. Even in this case, the same operation and effect as described above can be obtained.

The monitoring control circuit 15-1 measures the frequency of the system 2, calculates a detection level corresponding to the frequency, and transfers the detection level to the monitoring circuit 13-1. Exactly the same operation and effect can be obtained.

FIG. 4 is a block diagram showing a monitoring device for an analog input circuit according to a third embodiment of the digital protection relay device according to the present invention. The same parts as those in FIG. Are omitted, and different parts will be described here.

In the third embodiment, as shown in FIG. 4, in the first embodiment, in addition to the monitoring device 1 for the main detection relay, a monitoring device 21 for the fault detection relay is provided in parallel. This is applied when the same amount of electricity is input. In FIG. 4, the configuration on the relay body side is omitted.

The monitoring device 21 for the accident detection relay includes a monitoring signal generator 25 like the monitoring device for the main detection relay 1,
A superimposing circuit 26 for superimposing a monitoring signal having a predetermined frequency generated by the monitoring signal generator 25 on an input electric quantity from the system 2, and an analog input circuit to which the signal superimposed by the superimposing circuit 26 is input. 27, and a digital signal 28 converted by the analog input circuit 27, and a waveform discriminating circuit 30 for separating the digital signal 28 into a digital signal 12 and a monitoring signal digital signal 11 based on the amount of electricity input from the system. The digital signal 11 of the monitoring signal separated by the waveform discriminating circuit 30 is input, and when the failure of the analog input circuit 27 is detected, the monitoring failure signal 3
And a monitoring circuit 33 that outputs a signal No. 4.

In the monitoring device having such a configuration, the third
In the embodiment, the fault detection signal of the analog input circuit 7 detected by the monitoring circuit 13-2 and the fault detection relay 2 are sent to the monitoring control circuit 15-2 of the monitoring device 1 for the main detection relay.
When the failure detection signal of the analog circuit 27 detected by the first monitoring circuit 33 is also input, the lock signal is transmitted to the monitoring device 1.
A logic circuit 16 composed of an inhibit circuit to which the monitoring failure signal 14 is inputted from the monitoring circuit 13-2 of the above, and a logic circuit 36 composed of an inhibit circuit to which the failure detection signal 36 is inputted from the monitoring circuit 33 of the accident detection relay 21. These are provided to lock the output to a trip circuit and an alarm circuit (not shown).

Next, the operation of the monitoring device for the analog input circuit in the digital protection relay device configured as described above will be described. The digital signals 8 and 7 input from the analog input circuits 7 and 27 in the waveform classification circuits 10 and 30 will be described. The digital signal 11 of the monitoring signal obtained by separating the signals 28 is input to the monitoring circuits 13 and 33, respectively.

Here, the monitoring circuits 13-2 and 33 determine the effective value of the digital signal 11 of the monitoring signal,
The presence or absence of a failure in the analog input circuits 7 and 27 is determined based on whether or not the effective value is equal to or higher than a predetermined monitoring level, and when it is determined that there is a failure, monitoring failure signals 14 and 34 are output.

When the monitoring failure signals 14 and 34 are input to the monitoring and control circuit 15-2, the monitoring and control circuit 15-2 includes components other than the analog input circuit 7 of the main detection relay and the analog input circuit 27 of the fault detection relay. And a lock signal is given to each of the logic circuits 16 and 36 of the monitoring devices 1 and 21 to lock the monitoring failure signals 14 and 34 output to an alarm circuit (not shown).

According to the third embodiment having such a configuration, the monitoring devices 1 and 21 monitor the same amount of electricity input from the system 2 to the analog input circuits 7 and 27 of the main detection relay and the accident detection relay. The monitoring is performed by the circuits 13-2 and 33, and the lock signal is output only when the monitoring failure signal is input from the monitoring circuits 13-2 and 33 to the monitoring control circuit 15-2 of the monitoring apparatus 1. , Monitoring devices 1 and 21 due to factors other than failure of analog input circuits 7 and 27
Output of an unnecessary monitoring failure signal can be prevented.

FIG. 5 is a block diagram showing a monitoring device for an analog input circuit according to a fourth embodiment of the digital protection relay device according to the present invention. The same parts as those in FIG. Are omitted, and different parts will be described here.

In the fourth embodiment, the monitoring device 1 for the main detection relay and the monitoring device 21 for the accident detection relay
The monitoring circuits 13-3 and 33-1 are provided with a function of lowering the defect detection sensitivity (detection level), and the monitoring control circuit 15-3 of the monitoring device 1 is provided with a failure detection signal from the monitoring circuits 13-3 and 33-1. Are input to the monitoring circuits 13-3 and 33-1 to reduce the defect detection sensitivity.

According to the fourth embodiment having such a configuration, the same amount of electricity input from the system 2 to the analog input circuits 7, 27 of the main detection relay and the fault detection relay is monitored by the monitoring devices 1, 21. The monitoring is performed by the circuits 13-3 and 33-1 and only when a monitoring failure signal is input from the monitoring circuits 13-3 and 33-1 to the monitoring control circuit 15-3 of the monitoring device 1 is monitored. Monitoring circuit 13-
, 33-1 to provide a monitoring signal to the monitoring circuit 13-3, 3-3.
Since the failure detection sensitivity of 3-1 is reduced, it is possible to prevent the monitoring devices 1 and 21 from outputting unnecessary monitoring failure signals due to factors other than the failure of the analog input circuits 7 and 27.

FIG. 6 is a block diagram showing a monitoring device for an analog input circuit according to a fifth embodiment of the digital protection relay device according to the present invention. The same parts as those in FIG. Are omitted, and different parts will be described here.

In the fifth embodiment, as shown in FIG. 6, when an external condition signal 19 such as system operation of a circuit breaker or a switch is input to the monitoring control circuit 15-4, the monitoring circuit 13-4 outputs the signal. A lock signal is applied to a logic circuit 16 composed of an inhibit circuit to which a monitoring failure signal is input for a certain period of time to prevent the monitoring failure signal from being output to an alarm circuit (not shown). In this case, the monitoring control circuit 15-4 is provided with a timer that outputs a logic value "1" to the negative input terminal of the logic circuit 16 for a certain period of time when an external condition signal is input.

On the other hand, reference numeral 17 denotes a relay main body to which the digital signal of the input electric quantity separated by the waveform discriminating circuit 10 is inputted. This relay main body 17 performs the arithmetic processing necessary for the system protection of the digital signal of the input electric quantity. The protection output is input to a logic circuit 18 composed of an inhibit circuit, and a signal output from the logic circuit 16 of the monitoring device 1 is input to a negative input terminal. Output signal is locked.

In the fifth embodiment having such a configuration, the monitoring circuit 13-4 determines the effective value of the digital signal 11 for the monitoring signal, and determines whether the effective value is equal to or higher than a predetermined monitoring level. It is determined whether or not the analog input circuit 7 has a defect.
Is output.

In this case, even if the analog input circuit 7 does not have a defect, if the frequency of the system 2 fluctuates due to system operation of a circuit breaker or a switch in the system 2, the effective value obtained above fluctuates. The monitoring circuit 13 may output the monitoring failure signal 14 when the monitoring level becomes equal to or higher than the monitoring level.

At this time, the monitoring control circuit 15-4 fetches the external condition signal 19 that causes the system 2 to undergo a transient state change such as system operation, and receives a monitoring failure signal from the monitoring circuit 13-4. A lock signal is given to the circuit 16 for a fixed time to lock the output of the monitoring failure signal.

Therefore, it is possible to prevent the monitoring device 1 from outputting an unnecessary monitoring failure signal due to the operation of the system 2 and the like, not the failure of the analog input circuit 7.

FIG. 7 is a block diagram showing a monitoring device for an analog input circuit according to a sixth embodiment of the digital protection relay device according to the present invention. The same parts as those in FIG. Are omitted, and different parts will be described here.

In the sixth embodiment, as shown in FIG. 7, the monitoring circuit 13-5 has a function of lowering the defect detection sensitivity (detection level) by a circuit configuration as shown in FIG. When an external condition signal 19 for system operation such as a circuit breaker or a switch is input to the circuit 15-5, a timer (not shown) gives a command to switch the logical value "1" to the monitoring circuit 13-5 for a certain period of time to detect a failure. The sensitivity is reduced.

In the sixth embodiment having such a configuration, the monitoring circuit 13-5 obtains the effective value of the digital signal 11 of the monitoring signal, and determines whether the effective value is equal to or higher than a predetermined monitoring level. It is determined whether or not the analog input circuit 7 has a defect.
Is output.

In this case, even if the analog input circuit 7 has no defect, if the frequency of the system 2 fluctuates due to system operation of a circuit breaker or a switch in the system 2, the effective value obtained above fluctuates. The monitoring circuit 13-5 may output the monitoring failure signal 14 when the monitoring level exceeds the monitoring level.

At this time, when the monitoring control circuit 15-5 captures the external condition 19 that causes a transient state change in the system 2 such as the system operation, the monitoring circuit 13-5 outputs the logical value "1" to the monitoring circuit 13-5 for a certain period of time. By giving the switching command to lower the monitoring level, the effective value obtained by the monitoring circuit 13-5 does not exceed the monitoring level during that time, so that the monitoring failure signal 14 is output from the monitoring circuit 13-5. Never.

Therefore, it is possible to prevent the monitoring device 1 from outputting an unnecessary monitoring failure signal due to the operation of the system 2 or the like, not the failure of the analog input circuit 7.

FIG. 8 is a block diagram showing a monitoring device for an analog input circuit according to a seventh embodiment of the digital protection relay device according to the present invention. The same parts as those in FIG. Are omitted, and different parts will be described here.

In the seventh embodiment, as shown in FIG. 8, the monitoring circuit 13-6 monitors the plurality of channels of the analog input circuit 7 (for example, each part corresponding to each of the three phases). A function for determining whether the effective value of the digital signal 11 is equal to or higher than a predetermined monitoring level, and the monitoring control circuit 15-6 is provided with a monitoring circuit 13
Based on the determination signal input from -6, a function of estimating the presence or absence of a defect or a part based on the number of channels in which a defect is detected among the channels present in the analog input circuit 7 was presumed to be defective. Monitoring circuit 13-6 only when
Output a monitoring failure signal.

Here, various combinations are conceivable as the logic of the above estimation. The following method is shown as an example.

A) If the number of detected channels is one to several, it is estimated that the analog input circuit 7 is defective.

B) If a defect is detected in all or almost all channels, it is determined that the monitoring signal generator 5 is defective or the superimposing circuit 6 is defective.

C) Otherwise, it is determined that the frequency of the system 2 has fluctuated.

In this case, since b) and c) are not failures of the analog input circuit and do not affect the protection function, the monitoring control circuit 15-6 prevents the monitoring failure signal 14 from being output from the monitoring circuit 13-6. To lock.

According to the seventh embodiment having such a configuration, the presence or absence or location of a failure is estimated from the number of channels having a failure detected by the monitoring circuit 13-6. It is possible to prevent the monitoring apparatus 1 from outputting an unnecessary monitoring failure signal due to other factors instead of the failure.

As for the above-mentioned b), means for notifying the contents of the defect to the outside by another output signal may be considered.

On the other hand, in FIG.
The analog input circuit 7 having a plurality of channels may have a function of estimating the presence / absence or location of a defect based on detection of a defect in a specific channel.

Here, various combinations are conceivable for the logic of the above estimation. The following method is shown as an example.

A) When the voltage circuit detects a failure in all three phases, it is determined that the cause is the system 2.

B) When the current circuit detects a failure in all three phases, it is determined that the cause is the system 2.

In this case, since the analog input circuit 7 is not defective, the monitoring control circuit 15-6 locks so that the monitoring failure signal 14 is not output from the monitoring circuit 13-6.

Therefore, by using the monitoring circuit 13-6 and the monitoring control circuit 15-6, it is possible to output an unnecessary monitoring failure signal of the monitoring apparatus 1 due to other factors instead of the failure of the analog input circuit 7. Can be prevented.

In FIG. 8, the monitoring control circuit 15-
6, the effective value of the digital signal of the monitoring signal obtained by the monitoring circuit 13-6 is taken, and the relative value of the effective value between specific channels in the analog input circuit 7 having a plurality of channels is compared. It is also possible to provide a function of estimating the presence or absence or location of a defect based on the result, and lock the monitoring failure signal output from the monitoring circuit 13-6 when it is estimated that there is a failure by this function.

With such a configuration, the monitoring control circuit 1
5-6 indicates a monitoring failure signal 14 of the monitoring device 1 when the relative value of the effective value between specific channels in the analog input circuit 7 having a plurality of channels is equal to or less than a predetermined level.
To lock.

Here, various combinations for selecting the specific channel and comparing the relative values are conceivable. The following method is shown as an example.

The determination is made based on the relative values of the A-phase voltage and the B-phase voltage.

The determination is made based on the relative values of the B-phase voltage and the C-phase voltage.

The judgment is made based on the relative values of the C-phase voltage and the A-phase voltage.

If all of the above combinations are equal to or lower than the predetermined level, the monitoring control circuit 15-6 locks the output of the monitoring circuit 13-6 that monitors the voltage circuit.

Therefore, it is possible to prevent the monitoring apparatus 1 from outputting an unnecessary monitoring failure signal due to other factors, not the failure of the analog input circuit 7.

[0092]

As described above, according to the present invention, the operation of the system is locked by locking the output from the monitoring device against the output of an unnecessary monitoring failure signal caused by a factor other than the failure of the analog input circuit. It is possible to provide a digital protection relay capable of improving the rate.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a digital protection relay according to the present invention.
FIG. 2 is a block diagram of a monitoring device according to the embodiment.

FIG. 2 shows a second embodiment of a digital protection relay according to the present invention.
FIG. 2 is a block diagram of a monitoring device according to the embodiment.

FIG. 3 is a block diagram showing an example for explaining a function of a detection level of the monitoring circuit according to the embodiment;

FIG. 4 shows a third embodiment of the digital protection relay according to the present invention.
FIG. 2 is a block diagram of a monitoring device according to the embodiment.

FIG. 5 shows a fourth embodiment of the digital protection relay according to the present invention.
FIG. 2 is a block diagram of a monitoring device according to the embodiment.

FIG. 6 shows a fifth embodiment of the digital protection relay according to the present invention.
FIG. 2 is a block diagram of a monitoring device according to the embodiment.

FIG. 7 shows a sixth embodiment of the digital protection relay according to the present invention.
FIG. 2 is a block diagram of a monitoring device according to the embodiment.

FIG. 8 shows a seventh digital protection relay according to the present invention.
FIG. 2 is a block diagram of a monitoring device according to the embodiment.

[Explanation of symbols]

 1: Monitoring device 2: System 3: CT circuit 4: PT circuit 5: Monitoring signal generator 6: Superposition circuit 7: Analog input circuit 8: Digital signal 10: Waveform non-discrimination circuit 11: Digital signal of monitoring signal 12 : Digital signal of input electric quantity 13, 13-1 to 13-6: Monitoring circuit 14: Monitoring failure signal 15, 15-1 to 15-6: Monitoring control circuit 16, 18: Logic circuit 17: Relay body

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroshi Saito 1 Toshiba-cho, Fuchu-shi, Tokyo, Japan Inside the Fuchu Plant, Toshiba Corporation (72) Inventor Katsuhiko Sekiguchi 1-Toshiba-cho, Fuchu-shi, Tokyo, inside the Fuchu Plant, Toshiba ( 72) Inventor Naoyoshi Yamanaka 2-24-24 Harumi-cho, Fuchu-shi, Tokyo Toshiba System Technology Corporation F-term (reference) 2G036 AA19 AA27 BA07 BA40 CA06 CA08 CA10 5G042 FF02 FF24 FF32 GG02 GG09

Claims (9)

[Claims] 1. A digital protective relay having a monitoring device for inputting an electric quantity having a predetermined fundamental frequency and monitoring an analog input circuit for A / D conversion at a predetermined sampling frequency, wherein the monitoring device is Superimposing means for superimposing a known monitoring signal on an input electric quantity; discriminating means for discriminating a signal obtained after A / D conversion of the composite signal superimposed by the superimposing means by the analog input circuit; Monitoring means for determining whether or not the analog input circuit is defective based on whether the monitoring digital signal discriminated by the means is equal to or higher than a predetermined monitoring level, and a digital signal of the electric quantity discriminated by the discrimination means. Monitoring means for locking the output of the monitoring means when the frequency is out of the range of the allowable frequency. Digital protective relay device, characterized in that. 2. The digital protection relay device according to claim 1, wherein the monitoring control means reduces the monitoring level of the monitoring means when the frequency of the digital signal of the electric quantity is out of an allowable frequency range. A digital protection relay having a function of locking an output of a failure signal. 3. A digital type having a monitoring device for inputting an electric quantity having a predetermined fundamental frequency, respectively, and monitoring an analog input circuit of a main detection relay and an accident detection relay for A / D conversion at a predetermined sampling frequency. In the protective relay, the monitoring device for the main detection relay and the accident detection relay,
Superimposing means for superimposing a known monitoring signal on an input electric quantity, discriminating means for discriminating a signal obtained by A / D-converting the synthesized signal superimposed by the superimposing means by the analog input circuit, and discriminating means A monitoring means for determining whether or not the analog input circuit is defective based on whether or not the monitoring digital signal discriminated by the controller is equal to or higher than a predetermined monitoring level, and wherein any one of the main detection relay and the accident detection relay is provided. One of the monitoring devices is provided with monitoring control means for locking the outputs of the monitoring devices of the monitoring devices of the two relays when a monitoring failure signal is input from the monitoring device of the monitoring devices of the two relays. Characteristic digital protection relay. 4. The digital protection relay according to claim 3, wherein the monitoring control means provided in one of the monitoring devices of the main detection relay and the accident detection relay comprises:
When a monitoring failure signal is input from the monitoring means included in the monitoring device of both relays, a function of locking the output of the monitoring failure signal by lowering the monitoring level of the monitoring means included in the monitoring device of the quantity relay is provided. Characteristic digital protection relay. 5. The digital protection relay device according to claim 1, wherein the monitoring control means locks an output of the monitoring means for a predetermined time when a system condition signal such as switching of a circuit breaker or a switch is input. A digital protection relay characterized by having a function of causing the protection relay to operate. 6. The digital protection relay device according to claim 1, wherein the monitoring control means receives a digital signal for monitoring by the monitoring means when a system condition signal such as switching of a circuit breaker or a switch is input. A digital protection relay having a function of lowering a defect detection sensitivity for a certain period of time. 7. The digital protection relay device according to claim 1, wherein the monitoring control means has a function of estimating presence or absence of a failure or a part based on the number of detected channels among a plurality of analog input channels. A monitoring failure signal output from the monitoring means only when the failure is estimated to be defective. 8. The digital protection relay device according to claim 1, wherein the monitoring control means determines whether or not a fault is detected on the condition that a monitoring failure is detected in a specific associated channel among the plurality of analog input channels. A digital protection relay device having a function of estimating a part and determining a factor thereof, and locking a monitoring failure signal output from the monitoring means when there is a failure other than the analog input channel. . 9. The digital protection relay device according to claim 1, wherein the monitoring control means is configured to control the monitoring means if a level of a monitoring signal of a plurality of analog input channels is smaller than a relatively constant value. A digital protection relay having a function of locking an output.