KR20200038207A - Digital protection relay having protection function of infinite trip - Google Patents

Abstract

Disclosed is a digital protection relay having an infinite trip protection function. The digital protection relay having an infinite trip protection function comprises: an input unit receiving a state signal of a power system or a load device and receiving a relay condition and an operation signal for determining whether the state signal is abnormal from the outside; and an MCU unit connected to the input unit to monitor a state of the power system or the load device by comparing the state signal and the relay condition, determining an abnormality occurrence of the power system when the state signal is out of the relay condition, and generating a trip driving signal. The MCU unit can control a change in the relay condition through the input unit while maintaining a trip state by the trip driving signal.

Description

Digital protection relay having protection function of infinite trip

The present invention (Disclosure) relates to a digital protection relay, a digital having an infinite trip prevention function capable of resolving a state (so-called 'infinite trip state') that is repeatedly switched to a trip state after reset due to a problem of setting a trip criterion It relates to a protective relay.

Here, the background arts of the present invention are provided, and they do not necessarily mean the prior art.

In general, a digital protection relay (also called a digital motor protection relay) is installed and connected between the power system (power system in the power generation and transmission and distribution stage), that is, between the power supply side and the load device (normal motor), and the state of the power system and load device It is a device for monitoring and protecting.

The digital protection relay protects the power system and the load device by blocking the circuit between the power system and the load device by outputting a signal that drives and controls the circuit breaker that is connected to the circuit breaker to be alerted when an abnormality or accident occurs in the power system or load device do.

1 is a block diagram showing a configuration of a conventional digital protection relay. Referring to FIG. 1, when a current or voltage or temperature of a power system or a load device is detected from the state detection unit 2 and received as a state signal, an input unit ( 3) provides the received status signal to the controller 4.

When the status signal is input from the input unit 3, the control unit 4 displays the value of the status signal on the display unit 8, and the control unit 4 previously processes the processing program stored in the program storage means such as ROM. It reads and compares the input status signal with a preset reference value (voltage, current or temperature) according to the processing program, and if the input status signal is greater than or equal to the preset reference value, it is determined that an abnormality has occurred in the power system.

The control unit 4 outputs a control signal instructing the blocking operation to the digital output unit 5 to cut off the circuit of the power system where the accident occurred, and accordingly the digital output unit 5 trips to the external circuit breaker By outputting the signal, the circuit is cut off to protect the power system and load equipment.

Thereafter, a reset button is provided for restarting after correcting the errors of the disconnected power system and the load device.

Background arts related to this include Korean Patent Publication No. 10-2003-0003786, Japanese Patent Publication No. 2003-299214, and Korean Patent Publication No. 10-2003-0037922.

However, if the preset reference value, which is the comparison standard of the input status signal, is set incorrectly or if the judgment of normal or abnormal is set to the value of the ambiguous boundary, a trip drive signal is output even though the state of the power system and load device is substantially normal. There is a problem to be done.

In this case, even if an attempt is made to return to normal operation by the reset button, the output of the trip driving signal is repeated (so-called 'infinite trip state').

In order to solve this, it is necessary to correct the preset reference value rather than error correction of the power system and load device. In the conventional digital protection relay, it is impossible to change the set reference value because a trip driving signal is generated immediately after pressing the reset button. there is a problem.

1. Korea Patent Publication No. 10-2003-0003786 2. Japanese Patent Publication No. 2003-299214 3. Korean Patent Publication No. 10-2003-0037922

Disclosure of the Invention The present invention (Disclosure) is to provide a digital protection relay having an infinite trip prevention function capable of resolving a state (so-called 'infinite trip state') that is repeatedly switched to a trip state after reset due to a problem of setting a trip criterion. Is done.

Here, an overall summary of the present invention is provided, which should not be understood as limiting the periphery of the present invention (This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features).

To solve the above problems, a digital protection relay having an infinite trip prevention function according to an aspect of the present invention receives a status signal of a power system or a load device, and determines whether the status signal is abnormal from the outside. An input unit for receiving relay conditions and operation signals for determination; And connected to the input unit, monitors the state of the power system or the load device by comparing the status signal and the relay condition, and determines that an abnormality of the power system occurs when the status signal deviates from the relay condition and trips the drive signal. Including ,; MCU unit, characterized in that, while maintaining the trip state by the trip driving signal, while controlling the relaying condition to be changed through the input unit.

In a digital protection relay having an infinite trip prevention function according to an aspect of the present invention, the input unit includes a setting button for inputting the relay condition and the operation signal from the outside, and for resolving the trip driving signal. It may be provided as including a reset button.

In a digital protection relay having an infinite trip prevention function according to an aspect of the present invention, the MCU unit is provided to control to change the relay condition by an input signal through the setting button in the trip state. Can be.

In the digital protection relay having an infinite trip prevention function according to an aspect of the present invention, the MCU unit further includes a timer for detecting an elapse of time after the input signal is generated through the setting button. When the elapsed time detected by the timer exceeds a set time condition, it may be provided as limiting the change of the relay condition.

In a digital protection relay having an infinite trip prevention function according to an aspect of the present invention, an output control unit connected to the MCU unit to control the status signal, the relay condition and the external output of the trip driving signal; And an output unit connected to the output control unit and outputting information to the outside by an instruction of the output control unit.

According to the present invention, it is possible to escape the infinite trip state by controlling the MCU unit to change the relay condition through the input unit while maintaining the trip state by the trip driving signal.

According to the present invention, when a certain time elapses after switching from the trip state to the relay condition changeable state through the input unit, the control is made to limit the change of the relay condition, thereby inducing rapid resolution of the trip condition.

1 is a block diagram showing the configuration of a conventional digital protection relay.
2 is a block diagram of a digital protection relay having an infinite trip prevention function according to a first embodiment of the present invention.
3 is a control flowchart of FIG. 2.

Hereinafter, an embodiment in which a digital protection relay having an infinite trip prevention function according to the present invention is implemented will be described in detail with reference to the drawings.

However, the spirit of the present invention cannot be said to be limited by the embodiments described below, and those skilled in the art who understand the spirit of the present invention are included within the scope of the same technical spirit as the present disclosure. Although embodiments can be easily proposed as a method of substitution or modification, it is revealed that this is also included in the technical spirit of the present invention.

In addition, the terms used hereinafter are selected for convenience of explanation, and in grasping the technical contents of the present invention, it should not be limited to the dictionary meaning and should be interpreted appropriately in accordance with the technical spirit of the present invention.

2 is a block diagram of a digital protection relay having an infinite trip prevention function according to a first embodiment of the present invention, and FIG. 3 is a control flowchart of FIG. 2.

2 and 3, the digital protection relay 100 having an infinite trip prevention function according to the present embodiment includes an input unit 110, an MCU unit 120, an output control unit 130, and an output unit 140 It includes.

The input unit 110 is configured to receive a status signal of a power system or a load device and receive relay conditions and operation signals for determining whether the status signal is abnormal from the outside.

The status signal of the power system or load device is sensed by means for detecting the state of the power system or the state of the load device. It detects a current in the power system and provides a current transformer and a voltage in the power system. An example of this is a displacement transformer provided.

The input unit 110 converts and provides a low frequency filter circuit unit for removing high frequency noise among received status signals for accurate reception of the status signal, a multiplexer circuit unit for multiplexing, and a received analog signal into a digital signal. It may be configured to include an A / D converter circuit.

Meanwhile, the input unit 110 includes a setting button for input of a relay condition and an operation signal from the outside, and a reset button for resolving the trip driving signal.

The MCU unit 120 is connected to the input unit 110, monitors the state of the power system or the load device by comparing the status signal and the relay condition, and controls the operation of the digital protection relay 100 according to the present embodiment With the configuration, when the status signal exceeds the relay condition, it is determined that an abnormality occurs in the power system and a trip driving signal is generated.

The MCU unit 120 may be composed of a microprocessor, a central processing unit for integrated control and calculation, and a read only memory and a calculation for storing a series of processing programs. It may be configured to include a RAM (Random Access Memory) for temporarily storing the results.

Meanwhile, the main feature of the digital protection relay 100 according to the present embodiment is to control the MCU unit 120 to change the relay condition through the input unit 110 while maintaining the trip state by the trip driving signal. Is done.

This is to eliminate the infinite trip state that is repeated in the order of trip, reset, trip, reset, and when an input signal is generated through the setting button constituting the input unit 110 in the trip state, the relay condition is changed to a possible state. The control flow of the MCU unit 120 is changed as much as possible.

At this time, the MCU unit 120 further includes a timer (d) for detecting the passage of time after the occurrence of the input signal through the setting button, the elapsed time detected by the timer (d) exceeds the set time condition In this case, it is preferable to configure to limit the change of relay conditions.

Meanwhile, in the present embodiment, the output control unit 130 is connected to the MCU unit 120 to control the external output of the status signal, relay condition, and trip driving signal.

To this end, a plurality of controllers (f, g, h, i) may be provided.

Meanwhile, the output unit 140 is connected to the output control unit 130 and outputs information to the outside by an instruction of the output control unit 130.

In the present embodiment, in a state in which a relay condition can be changed through the input unit 110, the meaning of maintaining the trip state means that the operation of the output control unit 130 and the output unit 140 is maintained.

Next, the digital protection relay 100 having the infinite trip prevention function according to the present embodiment will be described in detail.

Referring to FIG. 1, in the digital protection relay 100 having an infinite trip prevention function according to the present embodiment, the input unit 110 includes a setting button (or setting switch (a)) for setting various relay conditions of the relay. , It consists of the input of current (b) and voltage (c) which are relay elements.

On the other hand, the MCU unit 120 for operating the system as a whole has an MCU (e) as a central processing unit, and a timer (d) for a resettable time.

The output control unit 130 and the output unit 140 are configured to output or display the main functions of the relay to the outside, and a plurality of controllers (f, g, h, i) constituting the output control unit 130, and output It is composed of a plurality of output means (j, k, l, m) constituting the unit 140.

Types include LCD controller (f) for LCD display (j) that displays relay settings, various information, and trip information, trip coil output (k) that outputs a signal that is the main function of relay when a relay (trip) occurs, and There is a trip coil controller (g) and a DO controller (h) for a DO (Digital Output: Realy) output (l) that can be used as an auxiliary output device when relaying.

In addition, it consists of a status LED display (m) and its status LED controller (i) for outputting various information such as the self-diagnosis function of the relay, the type of relay (trip), and the communication status with an externally interfaced device.

Next, referring to FIG. 2, the digital protection relay 100 having an infinite trip prevention function according to the present embodiment sets a trip condition related to current (b) and voltage (c) as relay elements (FIG. 1) After setting and saving in advance using the setting switch (a)), the operation is performed.

Thereafter, when the status is normal (not in the relay (trip) state), status information is displayed or the setting is changed, and the MCU (e) monitors whether the relay (trip) status is satisfied, and when the relay (trip) status is reached, the trip controller (g) To output the trip coil output (k) and output the status LED indication (m) from the status LED controller (i) according to the trip type.

In addition, the DO controller h operates according to whether the DO output 1 that is the auxiliary output device is used. In addition, details of the trip status are output through the LCD display (j) by the LCD controller (f).

On the other hand, the digital protection relay 100 having an infinite trip prevention function according to the present embodiment is provided with a function of operating any one of the previously provided setting button (setting switch (a) of FIG. 1) only in the trip state. do.

By this, when the change key input by the setting button is operated in the trip state, it operates in the change reset mode in the trip state, wherein the relay is currently in trip coil output (k), DO output (l), and LED display (m). While it is maintained, it is possible to reset the change and it is controlled.

On the other hand, at the same time as operating in the change reset mode, the timer d is activated and the LCD display j displays the resettable state.

From this time, while the timer (d) is running, it operates in the reset mode while maintaining the trip state, and the reset condition can be stored in the relay to be changed.

If the reset is not performed until the operation of the timer d is completed, the trip state before resetting is displayed again and the trip state is maintained.

However, if the reset is performed before the timer (d) operation is completed, it is determined again whether or not the trip is performed under the reset condition, and the trip state may be maintained even in the reset condition.

On the other hand, if the trip condition is out of the reset condition, a series of reset operations (trip coil reset, LED OFF, DO reset, timer reset) are executed and the system returns to the normal state.

Claims (1)

An input unit which receives a status signal of a power system or a load device and receives relay conditions and operation signals for determining whether the status signal is abnormal from the outside; And
It is connected to the input unit and monitors the status of the power system or load device by comparing the status signal and the relay condition. Includes; generating MCU unit,
The MCU unit, while maintaining a trip state by the trip driving signal, a digital protection relay having an infinite trip prevention function, characterized in that to control the change of the relay conditions through the input unit.

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