KR20180119782A - Protective relay with enhanced communication stability - Google Patents

Abstract

The present invention relates to a relay having enhanced communication stability. The relay according to an embodiment of the present invention includes: a transceiving part for exchanging data with another device through a communication line including a transmission line and a reception line; a fail-safe circuit which includes a first bias resistor connected to the transmission line, a second bias resistor connected to the reception line, and a termination resistor connected between the transmission line and the reception line; an input part for receiving the resistance value of at least one of the first bias resistor, the second bias resistor and the termination resistor; and a control part for adjusting the resistance value of at least one of the first bias resistor, the second bias resistor and the termination resistor according to a resistance value inputted through the input part.

Description

[0001] PROTECTIVE RELAY WITH ENHANCED COMMUNICATION STABILITY [0002]

The present invention relates to a relay having enhanced communication stability.

In the modern industry, stable supply of electricity to the plant is an important issue. The relay plays an important role in protecting facilities of power plants and substations as well as facilities of large and small factories by issuing a command to disconnect the circuit from the circuit when a short circuit or an overcurrent occurs in the circuit. Therefore, reliability and stability of relay operation are becoming more important.

The relay generally serves as a switch for opening and closing an electric circuit by using an electromagnetic force. In particular, it has an advantage that a large current or a high voltage can be easily opened and closed by a switch by electromagnetic force.

In the meantime, various relays such as mechanical relays and stationary relays have been developed. However, digital relays with complex and diverse functions have been developed with the development of digital technology in the 1990's. In general, digital relays are equipped with complex interlocking functions, breaker and switch functions, and accident waveform recording as well as measuring current and voltage.

In recent years, the development of digital relays capable of performing and monitoring the above-mentioned functions at a remote place by adding a communication function to existing relays reduces the monitoring and maintenance costs of the power system. In particular, as relays incorporating RS485 / RS232 serial communication functions have been developed and used, automation and unmanned substations have been made possible by allowing access to relays freely at remote locations through communication with higher-level HMI (Human Machine Interface) devices. to be.

FIG. 1 is a block diagram of a relay network connected to a communication line in order to send and receive data to and from other devices.

The relays 12, 14 and 16 and the upper HMI device 10 transmit and receive data through the communication lines L1 and L2 using the transceivers 101, 121, 141 and 161. The upper HMI device 10 can receive data on the operation status from the relays 12, 14 and 16 or transmit data for controlling the operation to the relays 12, 14 and 16.

In general, RS485 serial communication can be used for data transmission / reception between the relays 12, 14, 16 and the upper HMI device 10. [ At this time, the upper HMI device 10 operates as a master and the relays 12, 14 and 16 operate as a slave. The transmission / reception units 101, 121, 141, and 161 transmit necessary data through a serial communication method, and the communication lines L1 and L2 use a half-duplex line. The first termination resistor RT1 is provided to avoid reflection phenomenon on the cut surfaces of the communication lines L1 and L2.

1, a node connected to the communication lines L1 and L2 and the transmitting / receiving unit 101 of the upper HMI device 10 is provided with a pull-up resistor R1, (RT2), and a pull-down resistor (R2) are connected. Such a resistor connection configuration is generally referred to as a fail-safe circuit 18.

The upper HMI device 10 and the relays 12, 14, and 16 are all connected to the idle state of the HMI device 10 because the RS485 serial communication can transmit and receive data in both directions and send and receive data via a two- (101, 121, 141, 161) may output an incorrect logic level state (Logic Level State) when an error occurs or the communication lines L1, L2 are open.

For example, in the case of RS485 serial communication, if the voltage applied to the communication lines L1 and L2 must be equal to or greater than +/- 200 mV, the transmission / reception units 101, 121, 141, and 161 must be at a logic high level ) Or a logic low level (Logic Low Level). That is, for input voltages between -200 and +200 mV, the transceivers 101, 121, 141, and 161 may not be able to output a consistent output that is either a logic high level or a logic low level. There is a risk of malfunctioning of relay on / off when each relaying signal processing unit 122, 142, 162 controls the relay in accordance with a logic level state in which one of them is not defined.

Therefore, the communication lines L1 and L2 and the transmission / reception unit 101 of the upper HMI device 10, as shown in FIG. 1, are provided to improve the communication stability between the upper HMI device 10 and the relays 12, A second terminal resistor RT2 and a pull-down resistor R2 are connected to the node connected to the second terminal resistor RT2 and a bias voltage Vb of +/- 200 mV or more is applied to the second terminal resistor RT2 through the voltage division law, . The output of the transmission / reception units 101, 121, 141, and 161 is output to the upper HMI device 10 and the relays 12, 14, and 16 by the bias voltage Vb applied to the second terminal resistance RT2, A constant logic level state can be maintained even when an accident occurs in which the communication lines L1 and L2 are opened.

However, in a real industrial field, the point at which a relay is connected to a communication line is often changed. When the position of the relay is changed, the length and impedance of the communication line change depending on the position where the relay is installed, so that characteristics of the noise generated in the communication line may change. The magnitude of the bias voltage required by the transmission / reception section of the relay at the point of the communication line where different noise is generated may be varied. Therefore, in the relay network connected to the communication line, the fail-safe circuit provided at the node of the master device supplies a fixed bias voltage, which makes it difficult to move the relay .

Further, when a relay is additionally installed or a plurality of relays are installed, there may be a difference in the bias voltage range required by the transmission / reception unit of each relay depending on the length of the communication line and the position where each relay is installed. Therefore, it is not possible to satisfy the bias voltages of different ranges requested by the transmitting and receiving sections of all the relays by only the single bias voltage supplied from the fail-safe circuit provided at the node of the master device.

According to the present invention, by using a fail safe circuit composed of resistors capable of adjusting the resistance value, a bias voltage adjusted according to the position of the relay and the length of the communication line is supplied to the transmitter / receiver, And to provide an enhanced relay.

According to the present invention, a fail-safe circuit for a plurality of relays connected to a communication line is provided in a transmission / reception unit of each relay, so that a bias of a different range required by the transmission / reception unit of each relay, And to provide a relay having enhanced communication stability capable of independently supplying a voltage.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention which are not mentioned can be understood by the following description and more clearly understood by the embodiments of the present invention. It will also be readily apparent that the objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

A relay having enhanced communication stability according to an exemplary embodiment of the present invention includes a transceiver for exchanging data with another device through a communication line including a transmission line and a reception line, a first bias resistor connected to the transmission line, And a terminal resistance connected between the transmission line and the water drawer, wherein the resistance value of at least one of the first bias resistance, the second bias resistance and the termination resistance is inputted And a control unit for adjusting a resistance value of at least one of the first bias resistor, the second bias resistor and the termination resistor according to a resistance value input through the input unit and the input unit.

According to the present invention, by using a fail-safe circuit composed of resistors capable of adjusting the resistance value, a bias voltage adjusted according to the position where the relay is installed and the length of the communication line is supplied to the transceiver, There is an advantage that a relay having enhanced stability can be provided.

According to the present invention, a fail-safe circuit for a plurality of relays connected to a communication line is provided in the transmission / reception unit of each relay, so that a different range required by the transmission / reception unit of each relay depending on the length of the communication line and the position where each relay is installed It is possible to provide a relay having an enhanced communication stability capable of independently supplying a bias voltage of the bias voltage.

FIG. 1 is a block diagram of a relay network connected to a communication line in order to send and receive data to and from other devices.
2 is a block diagram of a relay having enhanced communication stability according to an embodiment of the present invention.
3 is a block diagram of a fail-safe circuit included in a relay having enhanced communication stability according to an embodiment of the present invention.
4 illustrates an example of the configuration of an input unit and an output unit included in a relay having enhanced communication stability in an embodiment of the present invention.
5 illustrates another example of the configuration of an input unit and a display unit included in a relay having enhanced communication stability in an embodiment of the present invention.
6 shows another configuration example of an input unit and an output unit included in a relay having enhanced communication stability in an embodiment of the present invention.

The above and other objects, features, and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings, which are not intended to limit the scope of the present invention. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to denote the same or similar elements.

Hereinafter, a configuration of a relay having enhanced communication stability including a fail-safe circuit according to an embodiment of the present invention will be described with reference to FIG. 2 and FIG.

2 is a block diagram of a relay having enhanced communication stability according to an embodiment of the present invention.

2, a relay 2 with enhanced communication stability according to an embodiment of the present invention includes a fail-safe circuit 21, a transmission / reception unit 22, a relay signal processing unit 23, a control unit 24, (25).

The relaying signal processing unit 23 can analyze the data relayed by the relay 2 through communication from another device. For example, it is possible to check whether data received from another relay or upper HMI device transmitted through the transmission / reception section 22 is a relay operation start command signal or a relay operation stop command signal.

The relaying signal processing unit 23 can generate data for transferring the operation details of the relay 2 to other devices. For example, when a power system problem occurs and the relay 2 performs a shutdown operation, data on the shutdown operation execution time and the number of times are transmitted to the other relay or the upper HMI device, (22).

The transmission / reception unit 22 transmits data received from another device via the communication line including the transmission line L4 and the reception line L3 to the relay signal processing unit 23, Data can be transmitted to other devices.

In an embodiment of the present invention, the relay 2 can perform communication using the RS485 serial communication method. For example, the relay 2 can perform communication via a two-wire half-duplex circuit system, which can transmit and receive in both directions and only one transmission at a time. According to the RS485 serial communication method, the communication line may be composed of only the transmission line L4 and the data transmission line L3, and the transmission and reception unit 22 may be composed of a transmitter and a receiver. According to the embodiment, a communication method other than the RS485 serial communication method may be applied to the relay 2 according to the present invention.

2, the fail-safe circuit 21 is connected to the nodes A and B of the transceiver 22 included in the relay 2 to supply a bias voltage to the transceiver 22.

The bias voltage of the connection nodes A and B of the transmission / reception unit L4 and the water supply line L3 is constant in the idle period of the communication network to which the relay 2 is connected The sending and receiving section 22 may output an undefined false logic level state. In order to solve this problem, the relay 2 according to an embodiment of the present invention includes a fail-safe circuit 21. The output of the transceiver 22 can maintain a constant logic level state even in the rest period of the communication network to which the relay 2 is connected through the bias voltage supplied by the fail safe circuit 21 according to the present invention.

3 is a block diagram of a fail-safe circuit included in a relay having enhanced communication stability according to an embodiment of the present invention.

The fail-safe circuit 21 includes a first bias resistor RA, a second bias resistor RB, and a termination resistor RT. Referring to FIG. 3, one end of the first bias resistor RA is connected to the voltage source VS and the other end is connected to the drain L3. One end of the second bias resistor RB is connected to the transmission line L4, and the other end is grounded. The terminal resistance RT is connected between the water line L3 and the line L4.

The termination resistance RT is applied with the bias voltage VAB calculated by the following Equation 1 by the voltage division law.

[Formula 1]

The resistance values of the first bias resistor RA, the second bias resistor RB, and the termination resistance RT can be adjusted by the control unit 24, which will be described later. Accordingly, as the resistance values of the first bias resistor RA, the second bias resistor RB, and the terminal resistor RT are adjusted, the magnitude of the bias voltage VAB applied to the terminating resistor RT can be adjusted. In one embodiment of the present invention, the first bias resistor RA, the second bias resistor RB, and the termination resistor RT may be any one of a digital variable resistor and an analog variable resistor. For example, the first bias resistor RA, the second bias resistor RB, and the termination resistor RT may be formed of a digital potentiometer.

2, the input unit 25 receives a resistance value of at least one of a first bias resistor, a second bias resistor, and a terminating resistor, and transmits the received resistance value to the controller 24. The user interface to be described later may include an input unit 25.

The control unit 24 may adjust the resistance value of at least one of the first bias resistor, the second bias resistor, and the terminating resistor according to a resistance value input from the user through the input unit 25. [ For example, the resistance value of the digital potentiometer constituting the first bias resistance, the second bias resistance and the termination resistance may be adjusted in a stepwise manner in accordance with the output of an MCU (Micro Controller Unit) included in the control unit 24. [

The fail safe circuit 21 including the resistors capable of adjusting the resistance value controls the resistances of the resistors through the control unit 24 so that the transmission and reception unit 22 is controlled according to the position where the relay 2 is installed and the length of the communication line. It is possible to supply a bias voltage suitable for the bias voltage. Therefore, there is no restriction due to the fixed resistance value of the fail-safe circuit when the relay 2 is installed to move, so that it is possible to freely install the relay.

In addition, when a relay network to which a plurality of relays are connected is configured, the fail-safe circuit 21 is installed in the transmission / reception unit 22 of each relay. Therefore, depending on the length of the communication line and the position where the relays are installed, Each of the fail safe circuits 21 can independently supply a bias voltage of a different range.

Referring again to FIG. 2, the relay 2 according to an embodiment of the present invention may further include a measurement unit 26 and a display unit 27.

The measurement unit 26 may be connected to the fail safe circuit 21 to measure the resistance values of the first bias resistance, the second bias resistance, and the termination resistance. Therefore, it is possible to check whether or not the resistance values of the first bias resistor, the second bias resistor, and the terminating resistor are normally adjusted according to the resistance value input through the input unit 25, through the resistance value measured by the measuring unit 26 .

The measurement section 26 is also connected to the fail-safe circuit 21 to measure the bias voltage supplied to the transmission-reception section 22 by the fail-safe circuit 21. [ The magnitude of the bias voltage supplied by the fail safe circuit 21 is increased or decreased in accordance with the resistance value of the first bias resistor, the second bias resistor and the termination resistance adjusted by the control unit 24. [ At this time, the measurement unit 26 can measure the magnitude of the increase / decrease bias voltage supplied to the transmission / reception unit 22 and the degree of increase / decrease of the voltage.

The display unit 27 is connected to the measuring unit 26 and detects the resistance value of the first bias resistor, the second bias resistor and the termination resistance measured by the measuring unit 26 and the resistance value of the bias voltage supplied by the fail- And the size of the second layer. The user interface to be described later may include a display unit 27. [

Hereinafter, the configuration and use examples of the input unit and the display unit included in the relay having enhanced communication stability according to an embodiment of the present invention will be described with reference to FIG. 4 to FIG.

4 shows an example of the configuration of an input unit and a display unit included in a relay having enhanced communication stability in an embodiment of the present invention.

2 and 4, the relay 2 according to an embodiment of the present invention may include a user interface 4 or may be connected to one side. The user interface 4 may comprise an input unit 25 and a display unit 27 included in the relay 2.

A setting resistance value for adjusting the resistance values of the first bias resistor, the second bias resistor and the termination resistor can be inputted through the input unit 25 of the user interface 4 and the display unit 27 of the user interface 4 The resistance value of the first bias resistor, the second bias resistor and the termination resistance actually adjusted according to the set resistance value, and the magnitude of the bias voltage supplied by the fail-safe circuit 21 can be displayed.

4, in one embodiment of the present invention, the input unit 25 includes an RFS button 42, an RT button 43, a setting bias resistance value display unit 44, a setting terminal resistance value display unit 45, And may include a dial node 46.

The user presses the RFS button 42 to check the resistance value of the first bias resistor and the second bias resistor and then confirms the resistance value displayed on the setting bias resistance value display 44 and rotates the dial node 46 The setting bias resistance value of the first bias resistor and the second bias resistor can be increased or decreased. Likewise, the user presses the RT button 43 to adjust the resistance value of the termination resistance, confirms the resistance value displayed on the set termination resistance value display part 45, and turns the dial node 46 to set the termination resistance The resistance value can be increased or decreased.

Referring again to FIG. 4, the display unit 27 may include an LED or an LCD screen 41. The display unit 27 is connected to the measuring unit 26 and includes a resistance value RFS of the first bias resistor and the second bias resistor measured by the measuring unit 26, a resistance value RT of the terminating resistance, (BIAS VOLTAGE) of the bias voltage supplied from the bias circuit 21 together with the measurement unit.

Therefore, the user checks whether or not the actual first bias resistance, the second bias resistance, and the resistance value of the terminating resistor are adjusted according to the set resistance value input to the input unit 25 by looking at the display unit 27 of the user interface 4, It is possible to check whether or not a desired bias voltage is supplied through adjustment of the resistance value of the bias resistor, the second bias resistor, and the termination resistor.

5 shows another configuration example of an input unit and an output unit included in a relay having enhanced communication stability in an embodiment of the present invention.

2 and 5, the relay 2 according to an embodiment of the present invention may include a user interface 5 or may be connected to one side. The user interface 5 may comprise an input unit 25 and a display unit 27 included in the relay 2.

Therefore, a setting resistance value for adjusting the resistance values of the first bias resistor, the second bias resistor and the termination resistance can be inputted through the input unit 25 of the user interface 5, and the display unit 27 The resistance value of the first bias resistor, the second bias resistor and the termination resistance actually adjusted according to the set resistance value and the magnitude of the bias voltage supplied by the fail-safe circuit 21 can be displayed.

5, the input unit 25 includes an RFS increase button 52, an RFS decrease button 53, an RT increase button 55, an RT decrease button 56, a setting bias resistance A value display section 54 and a set terminal resistance value display section 57. [

The user confirms the resistance value displayed on the setting bias resistance value display portion 54 and presses the RFS increase button 52 to adjust the resistance values of the first bias resistor and the second bias resistor, Bias Resistance Setting The bias resistance value can be increased or the RFS decreasing button 53 can be pressed to decrease the setting bias resistance value. Similarly, the user confirms the resistance value displayed on the set terminal resistance value display part 57 to adjust the resistance value of the terminal resistance RT, increases the set terminal resistance value by pressing the RT increase button 55, The decrease terminal 56 can be depressed to decrease the set terminal resistance value.

Referring again to FIG. 5, the display unit 27 may include an LED or an LCD screen 51. The display unit 27 is connected to the measuring unit 26 and includes a resistance value RFS of the first bias resistor and the second bias resistor measured by the measuring unit 26, a resistance value RT of the terminating resistance, (BIAS VOLTAGE) of the bias voltage supplied from the bias circuit 21 together with the measurement unit.

Therefore, the user can check whether or not the resistance value of the actual first bias resistor, the second bias resistor, and the terminating resistor is adjusted according to the set resistance value input to the input unit 25 by looking at the display unit 27 of the user interface 5, It is possible to check whether or not a desired bias voltage is supplied through adjustment of the resistance value of the bias resistor, the second bias resistor, and the termination resistor.

6 shows another configuration example of an input unit and an output unit included in a relay having enhanced communication stability in an embodiment of the present invention.

2 and 6, the relay 2 according to an embodiment of the present invention may include a user interface 6 or may be connected to one side. The user interface 6 may comprise an input unit 25 and a display unit 27 included in the relay 2.

A setting resistance value for adjusting the resistance values of the first bias resistor, the second bias resistor and the termination resistor can be inputted through the input unit 25 of the user interface 6, and the display unit 27 of the user interface 6 The resistance value of the first bias resistor, the second bias resistor and the termination resistance actually adjusted according to the set resistance value, and the magnitude of the bias voltage supplied by the fail-safe circuit 21 can be displayed.

Referring again to FIG. 6, the input unit 25 and the display unit 27 of the user interface 6 may be formed of a single touch screen. The touch screen may be an LED or an LCD touch screen. The touch screen may include a resistance value RFS of the first bias resistor and the second bias resistor measured by the measuring unit 26, a resistance value RT of the terminating resistance, (BIAS VOLTAGE) of the bias voltage supplied from the bias circuit 21 together with the measurement unit.

Therefore, the user can check whether the resistance value of the actual first bias resistor, the second bias resistor, and the terminating resistor is adjusted according to the set resistance value input to the input unit 25 by looking at the display unit 27 of the user interface 6, It is possible to check whether or not a desired bias voltage is supplied through adjustment of the resistance value of the bias resistor, the second bias resistor, and the termination resistor.

The input unit 25 may be a touch button displayed on a touch screen of the user interface 6. 6, the input unit 25 includes an RFS increase touch button 61, an RFS decrease touch button 62, an RT increase touch button 64, an RT decrease touch button 65, (63) and a set terminal resistance value display portion (66).

The user confirms the resistance value displayed on the setting bias resistance value display part 63 to adjust the resistance value of the first bias resistance and the second bias resistance and increases the setting bias resistance value by pressing the RFS increase touch button 61 Alternatively, the RFS reduction touch button 62 may be pressed to decrease the set bias resistance value. Similarly, the user can confirm the resistance value displayed on the set terminal resistance value display portion 66 to adjust the resistance value of the terminal resistance, increase the set terminal resistance value by pressing the RT increase touch button 64, By pressing the button 65, the set terminal resistance value can be decreased.

Referring again to FIG. 2, in an embodiment of the present invention, the measuring portion 26 of the relay 2 can measure the bias voltage supplied by the fail-safe circuit 21 in real time. The impedance and noise characteristics of the communication line may change due to changes in the surrounding environment such as failure or removal of other relays during the measurement of the bias voltage of the measuring unit 26. [ At this time, the measuring unit 26 can measure and sense a change in the bias voltage due to a change in the impedance and the noise characteristic of the communication line.

The measuring unit 26 can transmit information on the change in the bias voltage sensed through the measurement to the control unit 24. [ Thereafter, the control unit 24 compares the magnitude of the bias voltage before and after the change without inputting the resistance value through the input unit 25, and controls the first bias resistor to maintain the magnitude of the bias voltage before the change, The bias resistance and the resistance value of the termination resistance can be adjusted.

For example, when the magnitude of the bias voltage increases before the change in the magnitude of the bias voltage, the control section 24 can increase the resistance value of the first bias resistance and the second bias resistance or decrease the resistance value of the termination resistance. Conversely, when the magnitude of the bias voltage decreases before the change in the bias voltage magnitude, the control section 24 can decrease the resistance value of the first bias resistance and the second bias resistance, or increase the resistance value of the termination resistance.

In an embodiment of the present invention, the control unit 24 may be provided with an arithmetic expression or a voltage / resistance comparison table in advance so as to adjust the resistance values of the first bias resistor, the second bias resistor and the termination resistor according to the magnitude of the bias voltage before and after the change Can be stored. For example, the control unit 24 may calculate the degree of adjustment of the resistance value of the first bias resistor, the second bias resistor, and the terminating resistor by substituting the bias voltage magnitude before and after the change into the pre-stored equation. As another example, the control unit 24 can determine the degree of the resistance adjustment of the first bias resistor, the second bias resistor, and the termination resistor corresponding to the magnitude of the bias voltage before and after the change, with reference to the voltage / resistance comparison table stored in advance.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, But the present invention is not limited thereto.

Claims (6)

A transmission / reception unit for exchanging data with other devices via a communication line including a transmission line and a reception line;
A fail-safe circuit including a first bias resistor connected to the transmission line, a second bias resistor connected to the water line, and a termination resistor connected between the transmission line and the water line;
An input part for receiving a resistance value of at least one of the first bias resistor, the second bias resistor and the termination resistor;
And a control unit for adjusting a resistance value of at least one of the first bias resistor, the second bias resistor and the termination resistor according to a resistance value input through the input unit
Relay with enhanced communication stability
The method according to claim 1,
The first bias resistor, the second bias resistor, and the termination resistor
One of a digital variable resistance and an analog variable resistance
Relay with enhanced communication stability
The method according to claim 1,
The input unit
Button, a dial knob, and a touch screen
Relay with enhanced communication stability
The method according to claim 1,
And a bias voltage measuring unit for measuring a bias voltage supplied from the fail safe circuit
Relay with enhanced communication stability
5. The method of claim 4,
A display unit for displaying at least one of a resistance value of the first bias resistor, a resistance value of the second bias resistor, a resistance value of the terminating resistor, and a magnitude of a bias voltage supplied to the transceiver unit by the fail- Included
Relay with enhanced communication stability
5. The method of claim 4,
The control unit
And adjusting at least one of the resistance values of the first bias resistor, the second bias resistor and the termination resistance based on the bias voltage value measured by the bias voltage measurement unit
Relay with enhanced communication stability

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