KR20180070030A - Digital protection relay having protection function of infinite trip - Google Patents

Abstract

Disclosed is a digital protection relay with an infinite trip prevention function, which includes: an input unit for 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 or not, from the outside; and an MCU unit which is connected to the input unit, monitors the state of the power system or the load device by comparing the state signal with the relay condition, determines that the power system is abnormal when the state signal is out of the relay condition, and generates a trip driving signal. The MCU unit controls to change the relay condition through the input unit while maintaining a trip state by the trip driving signal. Accordingly, the present invention can get out of an infinite trip state.

Description

[0001] The present invention relates to a digital protection relay having an infinite trip prevention function,

Disclosure of the present invention relates to a digital protection relay, and more particularly, to a digital protection relay having an infinite trip prevention function capable of eliminating a state (so-called 'infinite trip state') in which a trip Protection relays.

Herein, the background art relating to the present invention is provided, and they are not necessarily referred to as known arts.

Generally, a digital protection relay (also called a digital motor protection relay) is connected between a power system (a power system at power generation and transmission and distribution stages), that is, between a power supply side and a load device (usually a motor) Is a device for monitoring and protecting.

The digital protection relay alerts the power system or load device in the event of an abnormality or an accident, and outputs a signal for driving and controlling the circuit breaker to be disconnected to shut off the circuit between the power system and the load device to protect the power system and the 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 a state detector 2 and received as a state signal, 3 provides the received status signal to the control unit 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 also reads the processing program stored in the program storage means such as ROM (Voltage, current, or temperature) according to the processing program and the input state signal. If the input state signal is equal to or greater than a predetermined reference value, it is determined that an abnormality has occurred in the power system.

The control unit 4 outputs a control signal for instructing the digital output unit 5 to cut off the drive in order to cut off the circuit of the power system in which an accident has occurred so that the digital output unit 5 can be tripped to an external circuit breaker By outputting a signal, the circuit is shut off to protect the power system and the load device.

Thereafter, a reset button is provided for restarting after correcting faults in the blocked power system and load equipment.

As background related to this, Korean Patent Laid-Open Nos. 10-2003-0003786, 2003-299214, and 10-2003-0037922 can be cited.

However, when the preset reference value as a comparison reference of the input state signal is set erroneously or the determination of the normal state and the abnormal state is set to a value of a boundary part that is ambiguous, a trip driving signal is outputted even if the state of the power system and the load device is substantially normal There is a problem.

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

In order to solve this problem, it is necessary to correct a preset reference value, not an error correction of a power system and a load device. In a conventional digital protection relay, it is impossible to change a set reference value after a trip driving signal is generated immediately after a reset button is pressed there is a problem.

1. Korean Patent Publication No. 10-2003-0003786 2. Japanese Patent Application Laid-Open No. 2003-299214 3. Korean Patent Publication No. 10-2003-0037922

Disclosure of the present invention is directed to providing a digital protection relay having an infinite trip prevention function capable of eliminating a state (so-called " infinite trip state ") in which a state is repeatedly switched to a trip state after reset due to a problem of trip reference setting .

The present invention is not intended to be exhaustive or to limit the scope of the present invention to the full scope of the present invention. of its features).

According to an aspect of the present invention, there is provided a digital protection relay having an infinite trip prevention function for receiving a status signal of a power system or a load device, An input unit for receiving a relay condition and an operation signal for judgment; And a control unit connected to the input unit, for monitoring the state of the power system or the load device by comparing the state signal and the relay condition, determining that the power system is abnormal when the state signal is out of the relay condition, And the MCU unit controls the relay condition so that the relay condition can be changed through the input unit while maintaining the trip state by the trip driving signal.

In the digital protection relay having the infinite trip prevention function according to an aspect of the present invention, the input unit may include a setting button for inputting the relay condition and the operation signal from the outside, And a reset button.

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

In a 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 elapsed time after the generation of the input signal through the setting button, And limiting the change of the relaying condition when the elapsed time sensed by the timer exceeds the set time condition.

An output control unit connected to the MCU unit and controlling an external output of the status signal, the relay condition, and the trip driving signal, in a digital protection relay having an infinite trip prevention function according to an aspect of the present invention; 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, the MCU can control the change of the relay condition through the input unit while maintaining the trip state by the trip drive signal, thereby making it possible to escape from the infinite trip state.

According to the present invention, when a certain time elapses after switching from the tripped state to the relaying condition changeable state through the input unit, the change of the relaying condition is restricted so as to promptly resolve the tripped state.

1 is a block diagram showing a 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;
Fig. 3 is a control flowchart of Fig. 2; Fig.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a digital protection relay having an infinite trip prevention function according to the present invention will be described in detail with reference to the drawings.

It is to be understood, however, that the scope of the present invention is not limited to the embodiments described below, and those skilled in the art of the present invention, other than the scope of the present invention, It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention.

In addition, the terms used below are selected for convenience of explanation. Therefore, the technical meaning of the present invention should not be limited to the prior meaning, but should be properly interpreted in accordance with the technical idea of the present invention.

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

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, .

The input unit 110 receives a status signal of a power system or a load device and receives a relay condition and an operation signal for determining whether the status signal is abnormal from the outside.

The status signal of the power system or the load device is detected by a means for detecting the state of the power system or the state of the load device, including a current transformer detecting and providing a current of the power system, For example, Potential Transformer is provided.

The input unit 110 includes a low frequency filter circuit unit for eliminating high frequency noise among the received status signals for accurate reception of the status signal, a multiplexer circuit unit for multiplexing, And an A / D converter circuit portion.

On the other hand, the input unit 110 includes a setting button for inputting relay conditions and an operation signal from the outside, and a reset button for canceling the trip driving signal.

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

The MCU unit 120 may be a microprocessor and includes a central processing unit for centralized control and calculation, a ROM (Read Only Memory) for storing a series of processing programs, A random access memory for temporarily storing the result, and the like.

On the other hand, the digital protection relay 100 according to the present embodiment controls the MCU unit 120 so that the relay condition can be changed via the input unit 110 while maintaining the trip state by the trip driving signal. .

This is for eliminating an infinite trip state repeated in the order of trip, reset, trip, and reset. When an input signal is generated through a setting button constituting the input unit 110 in a trip state, The control flow of the MCU unit 120 is changed.

In this case, the MCU unit 120 further includes a timer (d) for detecting the elapsed time after the generation of the input signal through the setting button. When the elapsed time detected by the timer (d) exceeds the set time condition It is preferable to limit the change of the relaying condition.

On the other hand, in the present embodiment, the output control section 130 is connected to the MCU section 120 and controls the external output of the status signal, the relay condition, and the trip driving signal.

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

On the other hand, 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, the fact that the relay condition is maintained while the relay condition is changeable via the input unit 110 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 as follows.

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

On the other hand, an MCU (e) as a central processing unit is provided in the MCU unit 120 which operates the system as a whole, and a timer (d) for a resettable time is provided.

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. The output control unit 130 includes a plurality of controllers f, g, h, i, And a plurality of output means (j, k, l, m) constituting a part (140).

(F) an LCD display (j) for displaying the relay setting, various information and trip information, a trip coil output (k) for outputting the main function of the relay at the time of trip (trip) There is a trip coil controller g and a DO controller h for digital output (Real) output (l) which can be used as an auxiliary output device during relaying.

In addition, it is composed of a status LED display (m) for outputting various information such as a self-diagnosis function of the relay, a type of trip (trip), a communication state with an external interface device, and an LED controller (i).

2, the digital protection relay 100 having the infinite trip prevention function according to the present embodiment sets the trip condition related to the current (b) and the voltage (c), which are relay elements, The setting switch (a) of Fig.

Thereafter, the MCU e monitors whether the status information is displayed, whether the setting is changed or not, and whether the relay (trip) state is satisfied. When the relay device is in a trip state, To output the trip coil output (k) and output the status LED indicator (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 is an auxiliary output device. 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 the infinite trip prevention function according to the present embodiment has a function of allowing any one of the setting buttons (the setting switches a in Fig. 1) do.

Thus, when the change key input by the setting button is operated in the trip state, the relay operates in the change reset mode from the trip state. At this time, the relay outputs the current trip coil output k, the DO output l, The change is reset and the state is controlled.

On the other hand, at the same time as operating in the change-over reset mode, the timer d is activated and the LCD display (j) displays a state where resetting is possible.

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

If resetting 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 reset is performed before the timer (d) operation is completed, it is judged again whether or not the trip is made under the reset condition, and the trip state can be maintained even in the reset condition.

On the other hand, when the tripped state is released from the reset condition, a series of reset operations (trip coil reset, LED OFF, DO reset, timer reset) are performed and return to the normal state.

Claims (5)

An input unit for receiving a status signal of a power system or a load device and receiving a relay condition and an operation signal for determining abnormality of the status signal from the outside; And
And a control unit connected to the input unit for monitoring the state of the power system or the load device by comparing the state signal with the relay condition and determining that the power system is abnormal when the state signal is out of the relay condition, And an MCU unit for generating the MCU,
Wherein the MCU unit controls the relay unit so that the relay condition can be changed through the input unit while maintaining the trip state by the trip driving signal. The method according to claim 1,
Wherein the input unit includes a setting button for inputting the relay condition and the operation signal from the outside, and a reset button for canceling the trip driving signal. The method of claim 2,
Wherein the MCU unit performs control so that the relay condition can be changed by an input signal through the setting button in the trip state. The method of claim 3,
The MCU unit,
And a timer for detecting an elapse of time after the generation of the input signal through the setting button,
Wherein the change of the relay condition is restricted when the elapsed time sensed by the timer exceeds a set time condition. The method according to claim 1,
An output control unit connected to the MCU unit and controlling an external output of the status signal, the relay condition, and the trip driving signal; And
And an output unit connected to the output control unit and outputting information to the outside by an instruction of the output control unit.

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