KR19990085704A - Digital relay measuring device - Google Patents

Abstract

The step-down means receives the three-phase alternating current signal to step down the three-phase alternating current signal to a predetermined level or less; A square wave generator converts the three-phase AC signal stepped down by the step-down means into a square wave and outputs the square wave; The waveform detector detects a rising point of each phase of the three-phase AC signal by receiving the square wave output from the square wave generator and comparing it with a reference clock pulse; The analog-to-digital converter receives the three-phase AC signal output by stepping down from the step-down means and outputs the analog signals of the plurality of current transformers and converts them into digitized digital signals; The control unit receives the rising point of each phase of the waveform detector and the digitized digital signal of the analog / digital converter, detects the phase difference / voltage of the three-phase AC signal, detects the amount of current of the plurality of current transformers, and then moves to the detected starting point of each phase. Repeatedly comparing the current amount with a pre-stored reference value and a setting value set by the user, outputting a predetermined control signal to an external device according to the result, and storing / displaying the detection result; The operation panel includes a plurality of keys so that the user can set a set value, and the three-phase AC phase difference / voltage and the current amount and error messages of the plurality of current transformers are displayed by the control signal of the controller. Therefore, the accuracy of the digital relay measuring apparatus is improved by converting the three-phase AC signal and the analog signal input from each current transformer into a digital signal and then outputting the digital signal through a processing process.

Description

Digital relay measuring device

The present invention relates to a digital relay measuring device, and more particularly, the three-phase AC signal (R, S, T), and the analog signal output from each current transformer is converted into a digital signal, the digital signal changed by the reference value and the user The present invention relates to a digital relay measuring device which cuts a transmission line according to a comparison result and simultaneously outputs a digital control signal to generate a warning in each warning device.

In general, the transmission and distribution lines and equipment constituting the transmission system are exposed to nature, so there is a risk of accidents. For this reason, the equipment connected to the power transmission system is greatly damaged by electrical and mechanical damage. Therefore, the line section where the failure occurs or the equipment should be removed from the power transmission system as soon as possible to eliminate the failure.

In this case, the breaker is automatically operated to eliminate the fault, but the fault type, fault current and voltage, and the location of the fault point are accurately measured to give a command to select and block the fault section at high speed. Relays are additionally used to fulfill the function of back light protection.

If such a relay is classified for use, it can be divided into a short circuit protection relay and a ground fault protection relay.

First, an over-current relay of the short-circuit protection relay operates when a current of a predetermined value or more flows, and is mainly installed in a power distribution line as well as a distribution line and a distribution board as well as various devices and lines.

The Over-Voltage Relay operates when a voltage above a certain value is applied, and the Under-Voltage Relay operates when a voltage drops below a certain value.

In addition, the over-current ground relay among the ground protection relays is used to protect the ground fault by specially reducing the operating current of the over-current relay, and the directional ground relay gives direction to the over-current ground protection relay. will be.

On the other hand, in order to control each relay described above, each relay is further provided with a measuring device.

However, these conventional relays and measurement devices have the following problems.

First, the measurement device receives an analog signal output from the relay, processes the input signal through a series of processes, and outputs the analog signal, thereby lowering the accuracy of the measurement device.

Secondly, by internally processing and outputting the signal, the user cannot observe the measurement process and results.

Third, one measuring device cannot detect all of phase difference / voltage, overcurrent, ground current, and the like of the three-phase AC signal by processing only the signal output from each relay.

Accordingly, an object of the present invention is to solve such problems, and an object of the present invention is to convert a three-phase alternating current signal and an analog signal input from each current transformer into a digital signal and then perform a series of processing steps to determine a predetermined digital signal. The control signal is output to improve the accuracy of the measuring device.

In addition, another object of the present invention is to display an input signal and a signal / result / status processed in the process so that the user can observe the measurement process and the result.

In addition, another object of the present invention is to perform a plurality of relay role as one digital relay measuring device without attaching a measuring device to each relay.

1 is a block diagram showing a digital relay measuring device according to the present invention,

2 is an exemplary view showing a display state of the LCD is initialized of the digital relay measuring device,

Figure 3a is an exemplary view showing how to set the size of the over-current and the ground fault current,

3b is an exemplary view showing an operation time setting in overcurrent and ground fault current;

3C is an exemplary view showing how to set the phase difference of each phase;

Figure 3d is an exemplary view showing the state of setting the overvoltage and undervoltage,

3E is an exemplary view showing contents displayed when an overcurrent is applied.

<Description of the code | symbol about the principal part of drawing>

10: step down 20: square wave generator

30: waveform detection unit 31: auxiliary central processing unit

32: first memory 40: amplifying circuit portion

41: amplifier circuit 42: rectified amplifier circuit

50: analog / digital converter 60: control unit

61: main CPU 62-64: 2-4 memory

70: operation panel 71: LCD

80: timer 90: decoder

100: amplification unit CT: current transformer

ZCT: Video Current Transformer R, S, T: 3 Phase AC Signal

A feature of the present invention for achieving the above object is that the step-down means receives a three-phase AC signal to step down the three-phase AC signal to a predetermined level or less; A square wave generator converts the three-phase AC signal stepped down by the step-down means into a square wave and outputs the square wave; The waveform detector detects a rising point of each phase of the three-phase AC signal by receiving the square wave output from the square wave generator and comparing it with a reference clock pulse; The analog-to-digital converter receives the three-phase AC signal output by stepping down from the step-down means and outputs the analog signals of the plurality of current transformers and converts them into digitized digital signals; The control unit receives the rising point of each phase of the waveform detector and the digitized digital signal of the analog / digital converter, detects the phase difference / voltage of the three-phase AC signal, detects the amount of current of the plurality of current transformers, and then moves to the detected starting point of each phase. Repeatedly comparing the current amount with a pre-stored reference value and a setting value set by the user, outputting a predetermined control signal to an external device according to the result, and storing / displaying the detection result; The operation panel includes a plurality of keys so that a user can set a set value, and the control panel of the control unit displays the phase difference / voltage of the three-phase AC signal, the current amount of the plurality of current transformers, error messages, and the like.

Preferably, the reference value is characterized in that the value is fixed to the initial setting state.

Preferably, the setting value is a value that the user arbitrarily sets within the allowable range of the reference value.

Preferably, a rectifying circuit further includes a rectifying circuit for rectifying signals of the AC component output from the step-down means and the plurality of current transformers into signals of the DC component between the step-down means and the output terminals of the plurality of current transformers and the input terminals of the analog / digital converter. It is done.

Preferably, the output terminal of the controller is a control signal that can be recognized by each component in the digital relay measuring device the measurement signal input from each component in the digital relay measuring device and the control signal output from the controller by the control signal of the controller. A decoder for changing is further included.

Preferably, the digital relay measuring device further comprises a timer for providing a reference clock pulse and time information.

The output terminal of the controller may further include an amplifier configured to amplify and output a predetermined control signal output from the controller.

Preferably, the waveform detection unit is connected to the output terminal of the square wave generator, the auxiliary central processing unit for receiving the output signal of the square wave generator to calculate the rising time of each phase of the three-phase AC signal; And a first memory in which a rising point of each phase is stored by a control signal of the auxiliary central processing unit.

Preferably, the control unit controls each component in the digital relay measuring device, and receives the output signal of the auxiliary central processing unit and the digitized digital signal output from the analog / digital converter, and the phase difference / voltage, current, etc. of the three-phase AC signal. A main central processing unit for detecting a; And a memory unit for storing reference values, set values, and data processed by the main CPU.

Optionally, the memory unit includes a second memory for storing various programs and reference values required for the system; A third memory configured to store setting values set by a user by a control signal of the main CPU; And a fourth memory for storing data processed by the main CPU by the control signal of the main CPU.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing a digital relay measuring apparatus according to the present invention, Figure 2 is an exemplary view showing a display state of the LCD is initialized of the digital relay measuring apparatus, Figure 3a is set the size of the over-current and the ground fault current Figure 3b is an exemplary view showing the setting of the value, Figure 3b is an exemplary view showing the setting of the operating time in the overcurrent and ground fault current, Figure 3c is an exemplary view showing the setting of the phase difference of each phase, Figure 3d FIG. 3E is an exemplary diagram illustrating setting of overvoltage and undervoltage, and FIG. 3E is a diagram illustrating contents displayed when overcurrent is applied.

Referring to FIG. 1, first, the step-down transformer 10 receives a three-phase AC signal (R, S, T) so as to step down the three-phase AC signal (R, S, T) below a predetermined level (4V). It is connected to the output terminals of the signals R, S, and T.

The square wave generator 20 is connected to the output terminal of the throttle 10 so as to convert the three-phase AC signals R, S, and T output down and down to a predetermined level from the throttle 10 into a square wave.

The waveform detector 30 includes an auxiliary central processing unit 31 and a first memory 32.

The auxiliary central processing unit 31 receives the square wave output from the square wave generator 20, calculates a rising point of each phase by comparing it with a reference clock pulse, stores it in the first memory 32, and simultaneously raises the rising point of each phase. Outputs to the other end. Here, the auxiliary central processing unit outputs an error signal if any one of the three-phase AC signals R, S, and T is reversed. In addition, the first memory 32 stores the rising time of each phase by the control signal of the auxiliary CPU 31.

The rectifier circuit 40 includes a rectifier circuit 41 for rectifying the signal of the AC component output from the step-down transformer 10 and the current transformer CT into a DC component, and a zero phase sequence current transformer ZZ. Amplified rectifier circuit 42 for amplifying and then rectifying the signal of the AC component output from

The analog-to-digital converter 50 is an analog signal output from the three-phase AC signal (R, S, T) and the rectifier circuit 41 of the rectifier circuit unit 30, and amplified / rectified by the amplification rectifier circuit 42 and outputs And converts the analog signal into a digitized digital signal.

The control unit 60 is composed of a main central processing unit 61, a second memory 62, a third memory 63, and a fourth memory 64. The main central processing unit 61 controls each component in the digital relay measuring device. In particular, the main central processing unit 61 receives a rising point of each phase output from the auxiliary central processing unit 31 of the waveform detection unit 30 and receives a three-phase alternating current signal R, Detects the phases of S and T, calculates the detected phase difference as a function of time, and radiates the difference to obtain a reference value previously stored in the second memory 62 and a user in the third memory 63. After comparing with the set value, it detects the abnormality and displays the detection result. When the error signal is output from the auxiliary CPU, the control signal is output so that the phase error message is displayed. In addition, the digital signal of the analog-to-digital converter 50 is input to detect the voltage of the three-phase AC signal (R, S, T) and the current of the current transformer (CT) / image current transformer (ZCT). 2 Repeatedly compares the reference value pre-stored in the memory 62 with the set value set by the user in the third memory 63, and outputs a digital control signal for controlling an external warning device while blocking the transmission line according to the result. It is configured to. The second memory 62 stores various programs, data, and the like, and in particular, reference values and voltages, currents, and the like of the three-phase AC signals R, S, and T according to the digital signals input from the analog / digital converter 50. It is stored as data in table form. Here, the reference value is fixed to the initial setting state. The third memory 63 stores a setting value input by the user through the operation panel 70 by a control signal of the main central processing unit 61. The fourth memory 64 stores various data processed by the main CPU 61. Herein, the setting value is a value set arbitrarily by the user within the allowable range.

The operation panel 70 includes a plurality of function keys (not shown) for storing the setting values set by the user in the third memory 63 of the control unit 60, and the main central processing unit of the control unit 60 ( 61) displays the phase difference / voltage of the three-phase AC signal according to the control signal and displays the current and various error messages of the current transformer (CT) / image current transformer (ZCT) and the like (Liquid Crystal Display) 71. It is composed.

The timer 80 is configured to provide a reference clock pulse to the auxiliary central processing unit 31 of the control unit 60 and time information to the main central processing unit 61.

Decoder 90 is a control signal output from the main central processing unit 61 of the control unit 60, the measurement signal input from each component in the digital relay measuring device and the main central processing unit 61 of the control unit 60 It is configured to change the control signal output from the control signal that can be recognized by each component in the digital relay measuring device.

The amplifier 100 is connected to an output terminal of the main CPU 61 to amplify a control signal output from the main CPU 61 of the controller 60.

Hereinafter, the operation of the digital relay measuring device according to the present invention will be described in detail.

First, when the system is turned on, the main CPU 61 outputs an output signal of the analog / digital converter 50 that converts and outputs an analog signal of the three-phase AC signal R, S, and T into a digitized digital signal. The voltage of the three-phase AC signal (R, S, T) according to the output signal of the analog-to-digital converter 50 in the second memory 62 is compared with the data stored in the form of a table, and the three-phase AC signal (R, After detecting the voltages of S and T, the LCD 71 is controlled to display the voltages of the three-phase AC signals R, S and T as shown in FIG.

In this state, when the user selects a predetermined function key for setting the voltage of the operation panel 70 and the current of the current transformer CT / image current transformer ZCT, the main CPU 61 of the control unit 60 decodes the decoder. The LCD 71 of the operation panel 70 is controlled through the 90 to display a screen as shown in FIG. 3A. In this state, the user can arbitrarily set a set value by adjusting the voltage of the three-phase AC signal (R, S, T) and the current of the current transformer (CT) / current transformer (ZCT) within the allowable range of the reference value. Here, the current transformer CT may adjust the range of overcurrent from 1A to 5A, and the image current transformer ZCT may adjust from 100mA to 500mA. In addition, the user can adjust the range of overvoltage from 230V to 270V as shown in FIG. 3D by using a predetermined function key for setting overvoltage and undervoltage, and adjust undervoltage to 170V to 210V. When the user completes all the settings and presses a predetermined function key on the operation panel 70 again, the main CPU 61 stores the setting values set by the user in the third memory 63.

In addition, the user can adjust the operation time (in seconds) at the overcurrent and the ground current as shown in FIG. 3B by using a predetermined function key for setting the operation time at the overcurrent and the ground current of the operation panel 70.

On the other hand, the user uses the predetermined function keys for setting the inclination of each phase of the three-phase AC signals R, S, and T of the operation panel 70, as shown in FIG. 3C, as shown in FIG. 3C. Each phase phase difference (10 degrees-90 degrees) of T) can be set. In addition, the user can set the time of the timer 80 by using a predetermined function key of the operation panel 70.

When the user finishes setting all the set values (for example, overcurrent is 1A, ground current is 100mA, each phase difference is 10 degrees, overvoltage is 270V, undervoltage is 170V), the main CPU 61 of the controller 60 The phase difference between the three-phase AC signals R, S, and T is detected as follows.

When the three-phase AC signal (R, S, T) is inputted to the square wave generator 20 by stepping down the three-phase AC signal (R, S, T) by stepping down from the step-down device 10 below a predetermined level, the square wave generator ( 20 generates a square wave shaped according to the three-phase AC signal (R, S, T), and outputs the generated square wave to the auxiliary central processing unit (31). In addition, the auxiliary CPU 31 reads the time when the R-phase of the square wave is raised, reads the next time of the rising of the S-phase, calculates the difference between the rising time of the R-phase and the S-phase while comparing the input square wave with the reference clock pulse. 1 is stored in the memory 32. In addition, as described above, the rising point of the S phase and the rising point of the T phase are calculated and stored in the first memory 32, and the rising points of the R, S, and T phases stored in the first memory 32 are stored in the main central processing unit ( 61) However, the auxiliary central processing unit 31 outputs an error signal to the main central processing unit 61 when any one of R, S, and T phases is reversed.

Then, the main CPU 61 calculates the phase difference of the R, S, and T phases at the rising points of the input R, S, and T phases, and then radians (angles) the repetitive comparison with the reference value / set value (that is, the reference value). After comparing with, compare the compared value with the set value again to detect whether the phase difference is exceeded.

Thus, when the phase difference of the three-phase AC signal (R, S, T) exceeds the reference value / set value, the data including the time point exceeded (that is, the current time of the timer 80) and the phase difference, etc. are stored in the fourth memory 64. ) And outputs a control signal to the LCD 71 of the operation panel 70 so that an error message is displayed on the LCD 71, and outputs a warning signal to another external warning device (warning bell, warning phone, etc.). do.

Then, the main CPU 61 receives the digitized digital signal output from the analog / digital converter 50 as described above, and inputs the input signal to the second memory 62 to the analog / digital converter 50. The voltage of the three-phase AC signal (R, S, T) according to the output signal of is compared with the data stored in the table form to detect the voltage of the three-phase AC signal (R, S, T). Then, the detection result is repeatedly compared to the reference value / set value, and when the comparison result exceeds the reference value / set value, the voltage of the detected time point and the detected three-phase AC signals R, S, and T are stored in the fourth memory 64. Display error messages (overvoltage, undervoltage, phase error, etc.) and output warning signals to other devices.

On the other hand, when a current of 1A or more is applied from the current transformer CT and the rectified signal is input to the analog / digital converter 50, the analog / digital converter 50 outputs the digitized digital signal. . Then, the main CPU 61 transmits the output signal of the analog / digital converter 50 input through the decoder 90 according to the output signal of the analog / digital converter 50 previously stored in the second memory 62. The amount of current is detected by comparing the amount with the data stored in a table form, and the amount of current is detected by comparing with the stored reference value / setting value. The main CPU 61 interrupts the transmission line for a predetermined time according to the operation time of the overcurrent set by the user and outputs a warning signal to another external device. In addition, as illustrated in FIG. 3E, the LCD 71 is controlled to display an overcurrent message, and the time point at which the overcurrent is detected (that is, the current time of the timer 80), the amount of overcurrent, and the like are stored in the fourth memory 64. Save it.

Similarly, when a current of 100 mA or more is applied from the image current transformer ZCT and the signal amplified / rectified through the amplifying rectifier circuit 42 is input to the analog / digital converter 50, the analog / digital converter 50 is digitalized. Output the signal. Then, the main CPU 61 detects the ground current amount by comparing the input digital signal with data stored in the form of ground current amount table according to the output signal of the analog / digital converter 50 previously stored in the second memory 62. When the ground current amount is more than the reference value / set value, the ground current (ie, short circuit) is determined. The main central processing unit 61 cuts off the transmission line for a predetermined time according to the operation time at the ground fault current set by the user, and outputs a warning signal to another device. In addition, the LCD 71 is controlled to display the ground current message, and the time point at which the ground current is detected (that is, the current time of the timer 80) and the ground current amount are stored in the fourth memory 64.

In addition, when the user presses a function key of the operation panel 70 to check the amount of overcurrent / ground fault current and the phase difference / voltage of each of the three-phase AC signals R, S, and T, the main central processing unit ( 61 controls the decoder 90 in accordance with a predetermined key of the selected operation panel 70 to output the digitized digital output from a specific component of each component of the digital relay measuring apparatus and output from the analog / digital converter 50. After detecting the signal and detecting the amount of current in the current transformer CT / image current transformer ZCT and the phase difference / voltage of each phase of the three-phase AC signal R, S, and T according to the detected signal, The selected one is displayed on the LCD 71 to confirm to the user. In addition, when a user presses a function key of the operation panel 70 to check data stored in the fourth memory 64, the main CPU 61 displays contents stored in the fourth memory 64.

Therefore, after converting the three-phase AC signal (R, S, T) and the analog signal output from the current transformer (CT) / video current transformer (ZCT) into a digital signal, a series of processes to process the overvoltage, Detect undervoltage, phase difference, overcurrent, ground fault current and compare with set value or reference value set by user, and if error occurs, cut off the power line and save / display it and output predetermined control signal Let the device generate a warning. In addition, if the user wants to check the overcurrent / ground fault current amount of the current transformer (CT) / image current transformer (ZCT) and the phase difference / voltage of each phase of the three-phase AC signal (R, S, T), the user can display it easily. Do.

As described above, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims below and equivalents thereof.

As described above, the present invention produces the following effects.

First, it is possible to improve the accuracy of the digital relay measuring apparatus by converting the three-phase AC signal and the analog signal input from each current transformer into a digital signal and then outputting it as a digital signal after processing.

Secondly, the user may observe the measurement process and the result by displaying the input signal and the signal / result / status processed in the process.

Fifth, a single relay measuring device can detect a three-phase AC signal / phase difference, an overcurrent, a ground current, and the like.

Claims (10)

Step-down means for receiving a three-phase alternating current signal and forcing down the three-phase alternating current signal to a predetermined level or less; A square wave generator for converting the three-phase AC signal stepped down by the step-down means into a square wave and outputting the square wave; A waveform detector which receives the square wave output from the square wave generator and detects a rising point of each phase of the three-phase AC signal by comparing with a reference clock pulse; An analog / digital converter which receives the three-phase AC signal and the analog signal of the plurality of current transformers, which are stepped down by a predetermined level and output from the step-down means, and converts the analog signal into a digital signal; The phase difference / voltage of the three-phase AC signal is detected by receiving the rising time of each phase of the waveform detector and the digitized digital signal of the analog / digital converter, and detecting the amount of current of the plurality of current transformers. A control unit for repeatedly comparing the current amount with a pre-stored reference value and a set value set by a user at each rising point of the phase, outputting a predetermined control signal to an external device according to the result, and storing / displaying a detection result; And It includes a plurality of keys so that the user can set the set value, and includes a control panel to display the three-phase AC phase difference / voltage, the current amount of the plurality of current transformers, error messages, etc. by the control signal of the controller Digital relay measuring device characterized in that. The digital relay measuring device according to claim 1, wherein the reference value is fixed at an initial setting state. The digital relay measuring device according to claim 1, wherein the set value is a value arbitrarily set by a user within an allowable range of the reference value. According to claim 1, Between the step-down means and the output stage of the plurality of current transformers and the input terminal of the analog / digital converter to rectify the signal of the AC component output from the step-down means and the plurality of current transformers respectively as a signal of a DC component Digital relay measuring device further comprises a rectifying circuit portion. According to claim 1, wherein the output terminal of the control unit by the control signal of the control unit, the measurement signal input from each component in the digital relay measuring device and the control signal output from the control unit each component in the digital relay measuring device. Digital relay measuring apparatus further comprises a decoder for changing to a control signal that can be recognized by. The digital relay measuring device of claim 1, wherein the digital relay measuring device further comprises a timer for providing the reference clock pulse and time information. The digital relay measuring device of claim 1, further comprising an amplifier configured to amplify and output a predetermined control signal output from the controller. The method of claim 1, wherein the waveform detector An auxiliary central processor connected to an output terminal of the square wave generator to calculate the rising time of each phase of the three-phase AC signal by receiving an output signal of the square wave generator; And a first memory for storing the rising point of each phase by a control signal of the auxiliary central processing unit. The method of claim 1, wherein the control unit It controls each component in the digital relay measuring device, and receives the output signal of the auxiliary central processing unit and the digitized digital signal output from the analog / digital converter, and the phase difference / voltage, current, etc. of the three-phase AC signal. A main central processing unit for detecting the; And And a memory unit for storing the reference value, the set value, and data processed by the main central processing unit. 10. The method of claim 9, wherein the memory unit A second memory for storing various programs required for a system and the reference value; A third memory in which the setting value set by the user is stored by a control signal of the main CPU; And And a fourth memory for storing data processed by the main central processing unit by the control signal of the main central processing unit.