JP5888941B2 - Protective relay - Google Patents

Description

  The present invention relates to a protective relay used for protecting a power system, and more particularly to a protective relay having a constant monitoring function for monitoring self-operation.

  A protective relay protects the power system by detecting an abnormality in the power system and controlling the circuit breaker. This type of protective relay has conventionally prevented erroneous control of the circuit breaker due to a failure in the device. In order to improve reliability, there are some protection processing units having a constant monitoring function for monitoring their own operation, which are operated in parallel, and the circuit breaker control output contacts of each protection processing unit are connected in series.

  In this case, when a state in which the circuit breaker control output contact cannot be controlled occurs, such as when an internal abnormality is detected in each protection processing unit or when the protection function is stopped to perform self-diagnosis (hereinafter referred to as these It is necessary to invalidate the control of the circuit breaker control output contact in each protection processing unit to prevent malfunction of the device.

Therefore, in the prior art, in each protection processing unit, a bypass control contact is added in parallel to the circuit breaker control output contact, and the parallel circuit of the circuit breaker control output contact and bypass control contact of each protection processing unit is duplicated in series. What has been configured to be connected is proposed. (See Patent Documents 1 and 2)

  In the conventional techniques described in Patent Documents 1 and 2, when each protection processing unit is normal without any internal abnormality, and when an abnormality occurs in the power system, the bypass control contacts of each protection processing unit are both opened. In this state, since both circuit breaker control output contacts are closed, the circuit breaker is tripped to protect the system.

  In addition, when one of the protection processing units has an internal abnormality, the bypass control contact is closed by the continuous monitoring function in the protection processing unit in which the internal abnormality has occurred, and does not depend on the open / close state of the circuit breaker control output contact. Therefore, the malfunction of the circuit breaker control output contact by the protection processing unit that caused the internal abnormality is prevented. When an abnormality occurs in the power system, the bypass control contact of each protection processing unit on the normal side remains open, and the circuit breaker control output contact is closed. Protected.

Japanese Patent No. 3256539 Utility Model Registration No. 2591452

  However, in the conventional protection relay as described in Patent Documents 1 and 2 above, the protection processing unit is duplicated and the bypass control contact is connected in parallel to the circuit breaker control output contact of each protection processing unit. Even when the parallel circuits are connected in series, the reliability as a protective relay may still be impaired.

In other words, even if one of the duplicated protection processing units has an internal abnormality, the protection processing unit without internal abnormality operates normally, so that reliability is maintained, but each protection processing unit is unfortunately both internal abnormality When this occurs, the bypass control contacts are both closed by the constant monitoring function. Then, a current flows through the bypass control contact of each protection processing unit to generate a circuit breaker control output. As a result, the circuit breaker is tripped.

  In order to prevent such a malfunction, for example, the continuous monitoring function of each protection processing unit is monitored together, and when it is determined by the continuous monitoring function that an internal abnormality has occurred in both protection processing units, the bypass control contact It is also possible to provide an interlock circuit that locks the closing operation of the bypass control contact by the constant monitoring function so that they are not closed together.

  However, in such a configuration, in addition to providing the above-described interlock circuit, a monitoring function unit for further monitoring the state of the constant monitoring function of each protection processing unit must be added. As the number of points increases and becomes complicated, there is a problem that the production cost increases and the reliability of the entire apparatus decreases.

  The present invention has been proposed in order to solve the above-described problems. The object of the present invention is to eliminate the need for an interlock circuit and the like, and without complicating the apparatus and with a simple configuration, compared with the conventional one. It is intended to provide a protective relay with improved reliability.

The protection relay according to the present invention is a protection relay in which a protection processing unit that performs arithmetic processing is duplicated, and each protection processing unit includes input conversion means that converts an electric quantity of a power system into a digital value, and the input conversion An abnormality in the power system is detected based on the output of the means, and the arithmetic means for controlling the first and second circuit breaker control output contacts by this abnormality detection output, and when an internal abnormality occurs by monitoring the internal state The first and second circuit breaker control output contacts are suppressed, the bypass command is generated, and the constant monitoring means for controlling the bypass control contact according to the bypass command is provided. The first circuit breaker control output contact to be controlled is connected in series, and in parallel with the first circuit breaker control output contact in one protection processing unit, in one protection processing unit Serial is obtained by connecting the series connection of the second circuit breaker control output contact in the bypass control contact and the other protective processor.

  In addition, the above-mentioned protective relay is provided with a pseudo input that gives the input conversion means a test signal equivalent to a voltage detection means implemented by a photocoupler or the like in parallel with each circuit breaker control output contact and an input current / voltage signal. Means are added.

  According to the protective relay of the present invention, it is possible to control so that both of the contacts that are closed at the time of bypass control and the contacts that are opened at the time of bypass control are not closed at the same time. Even when it is determined by the constant monitoring means that an internal abnormality has occurred in both protection processing units, it is possible to reliably prevent the occurrence of a problem that the circuit breaker is tripped by mistake. As a result, a conventional interlock circuit or the like is not required, and it is possible to provide a protective relay with higher reliability with a simple configuration without incurring complexity of the apparatus.

  Further, by adding a pseudo input circuit and voltage detection means, it is possible to automatically check the characteristics of each protection processing section.

It is a block diagram which shows the structure of the protection relay which concerns on Embodiment 1 of this invention. It is a circuit diagram which shows the operation state of the output contact of the protection relay of this invention. It is a block diagram which shows the structure of the protection relay which concerns on Embodiment 2 of this invention.

Embodiment 1.
1 is a block diagram showing a configuration of a protective relay according to Embodiment 1 of the present invention.

  In FIG. 1, the protection relay includes two protection processing units 1A and 1B that perform protection calculation processing. Here, in order to facilitate understanding of the invention, according to the necessity of distinguishing the protection processing units 1A and 1B, for convenience, one protection processing unit 1A is designated as an A-system protection processing unit and the other protection processing unit 1B. Is referred to as a B-system protection processing unit. Since each protection processing unit 1A, 1B basically has the same configuration and function, the configuration of the A-type protection processing unit 1A will be described in detail here.

The protection processing unit 1A receives an electric quantity of the electric power system, converts the signal into a digital value, and converts the signal into a digital value. The protection processing unit 1A is effective based on the electric quantity of the electric power system converted into a digital value by the input converting means 2A. A value calculation is performed, and the calculation unit 3A that detects the presence or absence of abnormality in the power system by comparing the calculation result with a preset set value and the internal state of the protection processing unit 1A are constantly monitored, and an internal abnormality occurs. If so, always-on monitoring means 4A for generating a bypass command,
The negative circuit 5A that inverts the output of the constant monitoring means 4A, the output of the negative circuit 5A and the output of the arithmetic means 3A are input, the logical product circuit 6A that outputs the logical product, and the output of the logical product circuit 6A. The first breaker control output contact 7A and the second breaker control output contact 8A to be controlled, and the bypass control contact 9A controlled by the output of the constant monitoring means 4A.

Here, the two circuit breaker control output contacts 7A and 8A and the bypass control contact 9A are normally open contacts. Further, the constant monitoring means 4A constantly monitors the internal state of the protection processing unit 1A including the input conversion means 2A and the calculation means 3A. When an internal abnormality occurs, a bypass command is generated and the bypass control contact 9A is set. It is something to control.

  The protection processing unit 1B having the same configuration as the protection processing unit 1A is configured such that the first circuit breaker control output contacts 7A and 7B that receive the outputs of the AND circuits 6A and 6B are connected in series. In parallel with the first circuit breaker control output contact 7A in the protection processing unit 1A, a series connection body of the bypass control contact 9A and the second circuit breaker control output contact 8B in the other protection processing unit 1B is connected. ing. Further, a series connection body of the bypass control contact 9B and the second circuit breaker control output contact 8A in the one protection processing unit 1A is similarly connected in parallel to the circuit breaker control output contact 7B in the other protection processing unit 1B. It is connected.

  As a specific example, the arithmetic means 3A detects an abnormality based on a current value and a time limit characteristic if the amount of electricity in the power system is an overcurrent element, and detects an abnormality due to a voltage value and an operating time if it is an undervoltage element / overvoltage element. If it is detected, or if it is a ground fault direction element, it detects an abnormality based on the zero-phase voltage value, zero-phase current value, its phase difference, and operation time. And the first circuit breaker control output contacts 7A and 7B are controlled by this signal to drive the circuit breaker opening coil 10 to protect the facility from the power system accident.

Next, the control operation of the output circuit composed of such circuit breaker control output contacts 7A, 7B, 8A, 8B and bypass control contacts 9A, 9B will be described with reference to FIG.
2 shows that (1) each protection processing unit 1A, 1B is normal without any internal abnormality, (2) if there is an internal abnormality in B-type protection processing unit 1B, (3) A-type When the internal abnormality occurs in the protection processing unit 1A, (4) the respective contact states when the internal abnormality occurs in both the A-system and B-system protection processing units 1A, 1B are shown.

(1) When each protection processing unit 1A, 1B is normal without any internal abnormality.
In this case, the bypass control contacts 9A and 9B of both protection processing units 1A and 1B are both in the open state as shown in FIG. Under this state, when an abnormality of the power system is detected by the arithmetic means 3A, 3B of each protection processing unit 1A, 1B, a circuit breaker control output signal is generated accordingly, Both A-system and B-system first circuit breaker control output contacts 7A, 7B are simultaneously closed. As a result, the circuit breaker opening coil 10 is driven to trip a circuit breaker (not shown), thereby protecting the facility from a power system accident.

(2) An internal abnormality has occurred in the B-system protection processing unit 1B.
In this case, when an internal abnormality of the protection processing unit 1B is detected by the B-system constant monitoring means 4B, a bypass command is generated from the constant monitoring means 4B accordingly, and thereby the bypass control contact 9B is closed, Bypass paths are formed for the circuit breaker control output contacts 7A and 8A. Further, the B-system circuit breaker control contacts 7B and 8B are kept open by the output of the B-system constant monitoring means 4B to form an output circuit as shown in FIG.

  Under this state, when an abnormality in the power system is detected by the A-system arithmetic means 3A, a circuit breaker control output signal is generated accordingly, and this signal causes the A-system circuit breaker control output to be generated. The contacts 7A and 8A are closed. At this time, the A system bypass control contact 9A is open, and the B system bypass control contact 9B is closed, so that the A system breaker control output contacts 7A and 8A and the B system bypass control contact 9B are connected. A current flows through the circuit breaker, and the circuit breaker opening coil 10 is driven to trip the circuit breaker, thereby protecting the facility from a power system accident.

(3) An internal abnormality has occurred in the A-system protection processing unit 1A.
In this case, when an internal abnormality of the protection processing unit 1A is detected by the A-system constant monitoring means 4A, a bypass command is generated in response thereto, whereby the bypass control contact 9A is closed and the circuit breaker control output contact is closed. A bypass path is formed for 7B and 8B. Further, the A-system circuit breaker control contacts 7A and 8A are maintained open by the output of the A-system constant monitoring means 4A, and an output circuit as shown in FIG. 2C is formed.

  Under this state, when an abnormality of the power system is detected by the B-system arithmetic means 3B, a circuit breaker control output signal is generated accordingly, and this signal causes the B-system protection processing section 1B to be generated. The circuit breaker control output contacts 7B and 8B are closed. At this time, the B system bypass control contact 9B is open and the A system bypass control contact 9A is closed, so that the B system circuit breaker control output contacts 7B and 8B and the A system bypass control contact 9A are connected. A current flows through the circuit breaker, and the circuit breaker opening coil 10 is driven to trip the circuit breaker, thereby protecting the facility from a power system accident.

(4) A case where an internal abnormality has occurred in both the A-system and B-system protection processing units 1A, 1B.
In this case, when an internal abnormality of the protection processing units 1A and 1B is detected by the continuous monitoring means 4A and 4B of both the A system and the B system, a bypass command is generated, whereby the bypass control contacts 9A and 9B are connected together. Although it is closed, the output of the control signal to each of the circuit breaker control output contacts 7A, 7B, 8A, 8B is suppressed via the negation circuits 5A, 5B, so as shown in FIG. It is not closed and erroneous output is prevented.

  As described above, in the protective relay including the pair of protection processing units 1A and 1B, the first circuit breaker control output contacts 7A and 7B are connected in series, and the respective circuit breaker control output contacts 7A and 7B are connected. By connecting the serial connection body of the bypass control contact 9A, 9B and the second circuit breaker control output contact 8B, 8A of the other protection processing unit 1B, 1A in parallel, it is simpler and more reliable. A protective relay can be obtained.

  By the way, it is supposed that the protective relay periodically performs a characteristic test, and it is necessary to measure an operation time until the circuit breaker control output is closed when a test signal is given to the input. In the first embodiment, when the constantly monitoring means 4A, 4B in the protection processing units 1A, 1B detect an internal abnormality, the circuit breaker control outputs 7A, 7B, 8A, 8B are suppressed. During the characteristic test, the characteristic test of the protection processing units 1A and 1B can be performed by adopting a configuration in which the outputs of the monitoring means 4A and 4B are not constantly suppressed.

Embodiment 2. FIG.
FIG. 3 is a block diagram showing the configuration of the protective relay according to the second embodiment for carrying out this characteristic test, and the components corresponding to those in the first embodiment are denoted by the same reference numerals.

In the figure, the protection relay is different from that of the first embodiment in that voltage detection means 11A, 11B including photocouplers connected in parallel with the respective circuit breaker control output contacts 7A, 7B of the protection processing units 1A, 1B; , Pseudo input generation means 12A and 12B are provided which give the input conversion means 2A and 2B an input equivalent to the input test signal at all times based on the signals from the monitoring means 4A and 4B.
Here, the output circuit composed of the circuit breaker control output contacts 7A, 7B, 8A, 8B and the bypass control contacts 9A, 9B and the circuit breaker opening coil 10 are connected in series, and voltage detection means 11A, 11B composed of a photocoupler or the like. Are connected in parallel to the first circuit breaker control output contacts 7A and 7B, respectively.

  Under such a configuration, in the normal state, the circuit breaker control output contacts 7A, 7B, 8A, 8B and the bypass control contacts 9A, 9B are all open, and the circuit breaker opening coil 10 receives current. It is kept out of flow. At this time, the voltage detection means 11A and 11B are configured to detect the voltage by a minute current that does not operate the circuit breaker, and the divided value of the power supply voltage is detected at the input of the voltage detection means 11A and 11B.

Next, when the breaker control output contacts 7A and 7B are closed, the input voltage of the corresponding voltage detecting means 11A and 11B becomes 0, and as a result, it is confirmed that the output contact is closed. Can do.
That is, after giving a test signal from the pseudo input conversion means 12A, 12B, the voltage detection means 11A, 11B monitors the voltage across the circuit breaker control output contacts 7A, 7B, thereby performing a characteristic test of the protection processing units 1A, 1B. It is possible to make it happen.

As described above, according to the present invention, a more reliable protective relay can be obtained with a simple configuration.
In the present invention, each embodiment can be appropriately modified or omitted within the scope of the invention.

1A, 1B: protection processing unit 2A, 2B: input conversion means 3A, 3B: calculation means 4A, 4B: constant monitoring means 5A, 5B: AND circuit 6A, 6B: negative circuit 7A, 7B: first circuit breaker control Output contact 8A, 8B: Second circuit breaker control output contact 9A, 9B: Bypass control contact 10: Circuit breaker opening coil 11A, 11B: Photocoupler 12A, 12B: Pseudo input generating means

Claims (3)

A protection relay in which a protection processing unit that performs arithmetic processing is duplicated, and each protection processing unit includes an input conversion unit that converts an electric quantity of the power system into a digital value, and an electric power system based on an output of the input conversion unit detecting the abnormality, the abnormality detection output by the first, and computing means for controlling the second breaker control output contacts of the first when the internal abnormality occurs to monitor the internal state, the second shut-off of And a constant monitoring means for suppressing the operation of the device control output contact, generating a bypass command, and controlling the bypass control contact in accordance with the bypass command,
The first circuit breaker control output contact controlled by each arithmetic means is connected in series, and one protection process is performed in parallel with the first circuit breaker control output contact in one protection processing section. A protective relay in which a series connection body of the bypass control contact in the section and the second circuit breaker control output contact in the other protection processing section is connected.   2. The protection according to claim 1, wherein the output of said constant monitoring means is inverted, and this output and the output of said arithmetic means are controlled by said first circuit breaker control output contact through an AND circuit. relay.   A voltage detection means connected in parallel with the first circuit breaker control output contact in the duplicated protection processing section and monitoring the voltage at both ends thereof, and a pseudo input generation means for giving a test signal to the input conversion means are added. The protective relay according to claim 1 or 2, characterized by the above.

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