KR101268620B1 - System and method for detecting the high impedence ground fault using distribution automation system - Google Patents

Abstract

A high resistance ground fault detection system and method using a distribution automation system that detects a fault condition based on a change in resistance of a high-resistance ground fault by a power line disconnection to a power distribution line before and after a fault are presented. The ground fault detection system with high resistance using the proposed distribution automation system is based on the phase voltage and the phase current detected in the circuit breaker or switch installed in each section of the distribution line divided into a plurality of sections, And determines whether or not a wire is disconnected in each section of the distribution line based on the fault resistance and normal resistance calculated on the basis of the fault information. When the circuit breaker or the switch And transmits the control signal to the corresponding remote terminal devices to separate the fault section.

Description

TECHNICAL FIELD [0001] The present invention relates to a system and method for detecting a high resistance ground fault using a distribution automation system,

The present invention relates to a system and method for detecting a high resistance ground fault using a distribution automation system, and more particularly, to a system and method for detecting a high resistance ground fault using a power distribution automation system for detecting occurrence of a high resistance ground fault The present invention relates to a fault detection apparatus and method.

Generally, a substation converts a transmission voltage transmitted through a transmission line to a distribution voltage, and supplies the converted distribution voltage to a customer through a distribution line. For example, a transmission voltage of 154 kV or 345 kV transmitted through a transmission line is converted to a distribution voltage of 22.9 kV in a substation and is distributed to a customer through a distribution line.

If a wire breaks due to a wire deterioration or defect in a distribution line that distributes a voltage to a customer, human accidents and equipment accidents will occur. At this time, the fault resistance is determined according to the type of the ground fault when the power line is disconnected, and the magnitude of the fault current is determined according to the magnitude of the fault resistance. At this time, there are two types of breakdown, ground fault and wire breakage, in case of wire disconnection in the processing distribution line.

1, the ground fault 10 indicates a failure of the distribution line due to a fault current generated by the contact resistance between the wire 20 and the ground 30 that has been broken while the wire 20 is broken. do. As shown in Fig. 2, the single-wire fault 40 means a failure due to a disconnection in a state in which there is no contact resistance. When such a contact resistance is small, a fault current largely occurs. On the contrary, when the contact resistance is large, a fault current is small. Current protection relays operate on fault currents larger than the set current. Accordingly, when a current smaller than the set current of the protection relay is generated when the electric wire 20 is disconnected and broken, the protection relay does not operate and the electric power is continuously supplied in a disconnected state, so that an electric shock or spreading accident occurs.

The magnitude of the contact resistance varies depending on the contact wire and the disconnected wire 20 when the wire is disconnected. The contact resistance is about 0 ~ 100 Ω when the ground fault 10 is complete, A high resistance ground fault 10 of about 100 to 1000 OMEGA occurs. Generally, the setting range of the protection relay is recognized as a fault current when a current more than 150% higher than the normal load (55) current is generated. Therefore, all the protection relays of the related art have a problem that the protection relay does not operate because current less than the load 55 current is generated when the high resistance ground fault 10 is generated. Particularly, a fault such as a single-wire fault 40 occurs, and a ground fault 10 current does not occur, and power is supplied only to two phases out of the three phases. As an example of the shape of the high-resistance ground fault 10, there are various types of failures such as contact with trees, contact with asphalt, contact with building roof, contact with vehicle bandages, and the like. In the distribution line, a protection relay is installed as a protection device for distribution lines to prevent accidents caused by aging or failure of the electric wire (20). Current protection relays are composed of Over Current Relay (OCR) operating at the current level and Over Current Ground Relay (OCGR) operating at the magnitude of the ground current. However, it is operated only at the magnitude of the currently used current, which causes a problem in that it does not operate at the time of the high resistance ground fault (10).

3, in the conventional distribution automation system, the distribution automation system 70 is configured to remotely control and monitor the switchgear 60 and the breaker 50 installed in the distribution line by communication. The difference between the switch 60 and the breaker 50 is that the switch 60 can detect a fault current but can not be cut off and the breaker 50 can cut off the fault current so that if a fault occurs in the line, , And transmits the blocking information to the host device 25 of the automation system. The worker 90 analyzes the failure information transmitted from the section switch 60 and the breaker 50 to the master unit and manually operates the switch 60 to turn on / .

4, in the conventional automation system, a plurality of remote terminal units (RTUs) 80 (RTUs) connected to the breaker 50 and the switch 60 are connected by a communication network, The worker 90 determines the high advantage by using the failure information FI detected by the breaker 50 and the breaker 60 in the main controller 25 and manually detects the breaker 50 or the breaker 50 On / off operation to separate and recover the fault section. For example, if a fault occurs in the distribution line, the fault current will generate a fault current up to the fault point. At this time, the breaker 60 or the breaker 50 installed within the fault section detects the fault current and transmits the fault information to the host. Since the breaker 60 or the breaker 50 installed outside the fault section does not generate a fault current There is no fault information. Accordingly, the failure information of the circuit breaker 50 and the breaker information 60 of the switch 60 are collected from the main controller 25 and the failure information is collected from the main controller 60. The worker 90 detects the failure location, (50) is turned on / off or the breaker (60) is turned on / off in the main unit, the fault section can be separated and the fault section can be recovered. As described above, the conventional failure section method is a method of judging a high advantage by a person (worker 90), and there is a problem that a high resistance is not known when a high resistance is generated.

Disclosure of Invention Technical Problem [8] The present invention has been proposed in order to solve the above-mentioned conventional problems, and it is an object of the present invention to provide a distribution automation system for detecting a fault condition based on a change in resistance between a power line before a fault and a power line after a fault, And to provide a high resistance ground fault detection system and method. That is, according to the present invention, the voltage and current are measured by using the breaker and the switch provided in each section of the distribution line, and the resistance state of each facility is monitored in the distribution automation main unit, Resistance ground fault detection system and method using a distribution automation system that detects a resistance ground fault.

Another object of the present invention is to provide a high-resistance ground fault device using a power distribution automation system that simultaneously detects a voltage and a current in each section of a power distribution automation device and discriminates a fault section based on the detected fault information, And to provide a detection system and method.

In order to achieve the above object, a high-resistance ground fault detection system using a distribution automation system according to an embodiment of the present invention includes: a voltage detection unit for detecting a fault voltage of a circuit breaker installed in each section of a distribution line divided into a plurality of sections, A plurality of remote terminal apparatuses for generating fault information including a current voltage and a phase voltage for each phase voltage before and after the occurrence of a fault event based on the current for each phase; And judging whether or not a wire is disconnected in each section of the distribution line based on the failure resistance and normal resistance calculated based on the failure information received from the plurality of remote terminal devices and controlling the breaker or switch of the section determined as wire disconnection And transmits the signal to the corresponding remote terminal devices to separate the fault section.

A plurality of power source side transformers installed on the power source side of the breaker or switch to detect the power source voltage and transmit the detected voltage to a remote terminal device installed in the breaker or switch; A plurality of load side transformers installed on each of the load side of the breaker or switch to detect the load side voltage and transmit the detected load side voltage to a remote terminal installed in the breaker or the switch; And a current transformer installed on the load side of the breaker or the switch to detect the current and transmit the detected current to the remote terminal installed in the breaker or the switch.

The power distribution master device calculates the normal resistance by using the voltage and the current before the occurrence of the failure event included in the failure information received from the plurality of remote devices and calculates the normal resistance by using the voltage and current after occurrence of the failure event included in the failure information, Calculate the resistance.

When the difference between the calculated fault resistance and normal resistance exceeds the resistance set value, the power distribution master device judges that the electric wire is broken in the corresponding section.

In the case where there are two switches in the section, the power distribution master unit calculates the value obtained by subtracting the resistance value of the power switch from the resistance value of the load side switch by the section resistance of the corresponding section, and if there are three or more switches in the section , The resistance value of the power source side switch and the resistance value of the remaining load side switch are subtracted from the largest resistance value among the resistance values of the load side switches to calculate the interval resistance of the corresponding interval.

The power distribution master device transmits a trip signal to the remote terminal device of the breaker installed in the section determined as the occurrence of the fault and restores the power failure by putting the normally open breaker into the healthy section.

When the current measured at the switch is less than the load current openable / closable current, the power distribution master maintains the cutoff state of the corresponding section.

The remote terminal device comprising: a video current trigger determination unit for generating a video current trigger when the variation value of the discrete signal per sample time exceeds a set value, by dividing the magnitude of the video current among the currents by the resolution; A video voltage trigger determination unit for generating a video voltage trigger when the variation value of the discrete signal per sample time exceeds the set value by dividing the magnitude of the video voltage among the voltages by the resolution, A non-voltage trigger determination unit for generating a non-voltage trigger when the voltages of the three phases are all below the no-voltage trigger set value; An RMS calculating unit for calculating a voltage, a current, and a phase angle before and after a trigger is generated when at least one trigger among the video current trigger, the video voltage trigger, and the no-voltage trigger occurs; An event generating unit for generating a fault event by comparing the voltage, current, and phase angle before and after trigger generation calculated by the RMS calculating unit with a reference value; And a fault information output unit for generating fault information including a voltage, a current, and a phase angle before and after the occurrence of the trigger, which is calculated when a fault event occurs in the event generating unit, and transmitting the generated fault information to the power distribution master.

The remote terminal apparatus further includes a terminal control unit for controlling the breaker and the switch according to the control signal received from the power distribution master device to recover the malfunction period.

The power distribution master device includes a fault pre- and post-fault data collecting unit for detecting and storing voltage, current and phase angles before and after a fault in fault information received from a plurality of remote terminal devices; A failure determination unit for determining whether a failure has occurred in each section of the distribution line based on the voltage, current, and phase angle before and after the failure collected in the data collection unit before and after the failure; A distribution controller for transmitting a breaker for separating a period determined as a failure in the failure determination unit and a switch control signal to a remote terminal device in a failure interval; And a master value output unit for outputting information on an interval determined as a failure occurrence by the failure determination unit and failure information.

The fault judgment unit calculates the fault resistance and the normal resistance based on the voltage and the current before and after the fault, and judges that the fault of the corresponding section occurs when the fluctuation value of the fault resistance and the normal resistance exceeds the reference value.

According to an aspect of the present invention, there is provided a method for detecting a high-resistance ground fault using a distribution automation system, comprising: collecting voltage and current of a plurality of breakers and switches installed in respective sections of a distribution line; Generating a fault event based on the collected voltage and current; Generating fault information including a voltage, a current, and a phase angle before and after occurrence of a fault event when a fault event occurs in a fault event generating step; Calculating a fault resistance and a normal resistance based on the generated fault information; Determining whether a fault has occurred in each section of the distribution line based on the calculated fault resistance and normal resistance; And a step of controlling the breakers and the switches installed in the fault section determined as the occurrence of the fault in the step of determining whether the fault has occurred to separate the fault section from the power distribution line.

The step of collecting the voltage and the current includes the steps of: detecting the voltage on the power source side for each of the phases on the power source side of the circuit breaker or the switch; Detecting a load-side voltage for each of the loads on the load side of the circuit breaker or the switch; And sensing current on each side of the load side of the breaker or switch.

Calculating the fault resistance and the normal resistance may include calculating a normal resistance using voltage and current before occurrence of a fault event included in the fault information received from the plurality of remote devices; And calculating the fault resistance using the voltage and current after occurrence of the fault event included in the fault information.

In the step of calculating the fault resistance and the normal resistance, when there are two switches in the section, the value obtained by subtracting the resistance value of the power switch from the resistance value of the load side switch is calculated as the section resistance of the corresponding section, If there are three or more units, the value obtained by subtracting the resistance value of the power source side switch and the resistance value of the remaining load side switch at the largest resistance value among the resistance values of the load side switches is calculated as the interval resistance of the corresponding interval.

In the step of determining whether or not a fault has occurred, if the difference between the calculated fault resistance and normal resistance exceeds the resistance set value, it is determined that the electric line is broken in the corresponding section.

The step of separating the fault section from the power distribution line includes the steps of transmitting a trip signal to the remote terminals of the breaker and the breaker installed in the section judged as the fault occurrence; And a step of charging the normal open-circuit breaker into the healthy section to recover the power failure.

The step of separating the fault section from the power distribution line further includes the step of maintaining the blocking state of the section when the current measured by the switch is less than the load current openable and closable current.

Generating a fault event comprises: generating a video current trigger when the variation value of the discrete signal per sample time exceeds a set value, by dividing the magnitude of the video current among the currents by the resolution; Generating a video voltage trigger when the variation value of the discrete signal per sample time exceeds a set value by dividing the magnitude of the video voltage among the voltages by the resolution, Generating a no-voltage trigger if all three voltages are below a no-voltage trigger setpoint; Calculating at least one voltage, current, and phase angle before and after trigger generation if at least one trigger occurs between the video current trigger, the video voltage trigger, and the no-voltage trigger; And generating a fault event by comparing the voltage, current, and phase angle before and after the trigger occurrence, with the reference value.

And outputting information on a fault zone determined as a fault occurrence and fault information in a step of determining whether a fault has occurred.

In the step of judging whether or not a fault has occurred, if the variation value of the fault resistance and the normal resistance exceeds the reference value, it is judged that the fault has occurred in the corresponding section.

According to the present invention, a high-resistance ground fault monitoring system and method using a power distribution automation system detects a fault in a power line by sensing a change in resistance of a distribution line and detecting a fault, It is possible to detect the high advantage regardless of the magnitude of the fault current when a high resistance ground fault which can not be detected can be detected.

In addition, the high-resistance ground fault detection system and method using the distribution automation system can prevent the fault current not only in the breaker but also in the breaker by interrupting the fault current through the remote control of the interval master have.

1 to 4 are views for explaining a ground fault detection method using a conventional distribution automation system.
5 is a block diagram illustrating a high-resistance ground fault detection system using a distribution automation system according to an embodiment of the present invention.
Fig. 6 is a view for explaining the switch and the breaker of Fig. 5; Fig.
7 is a view for explaining the remote terminal apparatus of Fig. 5; Fig.
Figs. 8 and 9 are diagrams for explaining the RMS calculating unit of Fig. 7; Fig.
FIG. 10 is a view for explaining a power distribution master of FIG. 5; FIG.
Figs. 11 to 15 are diagrams for explaining the failure determination unit of Fig. 8; Fig.
16 and 17 are diagrams for explaining the difference between a distribution automation system and a conventional system according to an embodiment of the present invention when two types of ground fault failure occur in a processing distribution line.
18 is a view for explaining a high-resistance ground fault detection method using a distribution automation system according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to facilitate a person skilled in the art to easily carry out the technical idea of the present invention. . In the drawings, the same reference numerals are used to designate the same or similar components throughout the drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a high resistance ground fault detection system using a distribution automation system according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. 5 is a block diagram illustrating a high-resistance ground fault detection system using a distribution automation system according to an embodiment of the present invention. 6 is a view for explaining the switch and the breaker of FIG. FIG. 7 is a view for explaining the remote terminal apparatus of FIG. 5, and FIGS. 8 and 9 are views for explaining the RMS calculating unit of FIG. FIG. 10 is a view for explaining the power distribution master of FIG. 5, and FIGS. 11 to 15 are views for explaining the failure determination unit of FIG.

5, a high-resistance ground fault 10 detection system using a distribution automation system includes a plurality of breakers 100, a plurality of switches 200, the plurality of breakers 100, and a plurality of switches 200 A plurality of remote terminal devices 400 installed in each of the plurality of remote terminal devices 400, and a power distribution master device 500.

The plurality of breakers 100 and the plurality of switches 200 detect the voltage and the current and transmit the detected voltage and current to the corresponding remote terminal 400. 6, each of the plurality of breaker 100 and the plurality of switches 200 includes a plurality of power source side transformers (not shown) for measuring the power and current of the power line and transmitting the measured power and current to the remote terminal 400, (140, 240), a plurality of load side transformers (160, 260), and a plurality of current deflectors (180, 280). The plurality of power source side transformers 140 and 240 and the plurality of load side transformers 160 and 260 and the plurality of converters 180 and 280 continuously detect the voltage and current of the circuit breaker 100 and the switch 200, To the terminal device (400). The plurality of power source side transformers 140 and 240 and the plurality of load side transformers 160 and 260 and the plurality of converters 180 and 280 are controlled by the control signal from the remote terminal device 400 to generate a voltage and a current And the voltage and current after the occurrence of the fault event, and transmits the measured voltage and current to the remote terminal apparatus 400.

The plurality of power source side transformers 140 and 240 are installed in phases (i.e., A phase, B phase, and C phase) on the power source side of the circuit breaker 100 or the switch 200 to detect the power source side voltage. One side of the power source side transformers 140 and 240 is connected to the power line 20 connecting the power source side of the circuit breaker 100 or the switchgear 200 and the contacts 120 and 220 and the other side is grounded to detect the power source side voltage .

The plurality of load side transformers 160 and 260 are provided on each phase of the load side of the circuit breaker 100 or the switch 200 (i.e., A phase, B phase, and C phase) to detect the load side voltage. One side of the load side transformers 160 and 260 is connected to the electric wire 20 connecting the contact points 120 and 220 and the load side of the breaker 100 or the switch 200 and the other side is grounded to detect the load side voltage .

The plurality of current transformers 180 and 280 are installed on the respective phases of the load circuit side of the circuit breaker 100 or the switch 200 (i.e., A phase, B phase, and C phase) to detect current. One side of the current transformers 180 and 280 is connected to the output side wire 20 of the contacts 120 and 220 and the other side is connected to the load side wire 20 of the breaker 100 or the switch 200, do.

The plurality of circuit breakers 100 and the plurality of switches 200 separate the corresponding section from the power line according to a control signal received from the remote terminal apparatus 400.

Each of the plurality of remote terminal apparatuses 400 is connected to one of a plurality of breakers 100 or a plurality of switches 200 installed in each section of a power line. At this time, each of the plurality of remote terminal apparatuses 400 generates a fault event based on the voltage and the current of each phase detected by the circuit breaker 100 or the switch 200 connected thereto. Each of the plurality of remote terminal apparatuses (400) controls the circuit breaker (100) or the switch (200) so as to detect a voltage and a phase current before and after occurrence of a failure event. Each of the plurality of remote terminal apparatuses 400 generates failure information including a current voltage and a phase current of each of the plurality of remote terminal apparatuses before and after occurrence of a failure event received from the corresponding circuit breaker 100 or the switch 200, Lt; / RTI > Each of the plurality of remote terminal devices 400 turns on / off the corresponding circuit breaker 100 or the switch 200 according to a control signal from the power distribution master device 500 to separate the faulty section from the power line.

7, the remote terminal apparatus 400 includes a video current trigger determination unit 410, a video voltage trigger determination unit 420, a voltage-free trigger determination unit 430, an RMS calculation unit 440 An event setting unit 450, an event generating unit 460, a failure information outputting unit 470, a terminal communication unit 480, and a terminal control unit 490.

The video current trigger determination unit 410 generates a trigger based on the video current. That is, if the variation value of the discrete signal per sample time is larger than the set value, the video current trigger determination unit 410 divides the size of the video current among the currents received from the breaker 100 or the switch 200, do.

The video voltage trigger determination unit 420 generates a trigger based on the video voltage. That is, when the variation value of the discrete signal per sample time is larger than the set value, the video voltage trigger determination unit 420 divides the magnitude of the image voltage among the voltage values received from the breaker 100 or the switch 200, do.

The non-voltage trigger determination unit 430 generates a failure event based on the three-phase voltage. That is, when the voltages of the three phases (i.e., the A-phase, the B-phase, and the C-phase) fall below the non-voltage trigger set value, the non-voltage trigger determination unit 430 determines that the voltage- do.

When a trigger occurs, the RMS calculating unit 440 calculates the voltage, current, and phase before and after the trigger occurrence based on the occurrence time of the trigger. That is, when at least one trigger among the video current trigger, the video voltage trigger, and the no-voltage trigger occurs, the RMS calculator 440 calculates the voltage, current, phase, and failure And calculates the post-voltage, current, and phase. 8 and 9, the RMS calculation method before and after the occurrence of the video voltage and current failure event in the RMS calculation unit 440 calculates the RMS value of the time set before the failure event and the time after the failure event at the trigger time The values before and after the fault are compared. However, when a voltage-free fault event occurs, the fault is detected before the fault occurs at the point of no-voltage interruption trigger. In addition, since the trigger point before the trigger point is recognized as a power failure at the time of the uninterruptible power take-off trigger, it is a method of determining before and after the fault event except the power failure interval between the non-voltage outage trigger point and the non- Particularly, in order to calculate the RMS value before and after the failure, the default value is calculated as 12CYCLE before the failure and 12CYCLE after the failure, and is set to 0 to 60CYCLE intervals according to the set time before and after the failure.

The event setting unit 450 sets a current set value, a voltage set value, and a phase set value as criteria for determining whether a failure event has occurred.

The event generator 460 compares the pre-failure voltage, current, phase, and post-failure voltage, current, and phase calculated by the RMS calculator 440 with reference values to generate a failure event. To this end, the event generating unit 460 compares the voltage, current, and phase calculated by the RMS calculating unit 440 with the current setting value, the voltage setting value, and the phase setting value set by the event setting unit 450, It is determined whether an event has occurred or not. Here, the event generating unit 460 generates a fault event when the value calculated by the RMS calculating unit 440 exceeds the set value. The event generator 460 generates a pre-failure event and a post-failure event.

The fault information output unit 470 outputs fault information including voltage, current, and phase before and after the occurrence of a fault event when a fault event occurs in the event generator 460. [

The terminal communication unit 480 transmits the failure information output from the failure information output unit 470 to the power distribution master device 500. The terminal communication unit 480 receives a control signal for disconnecting or restoring a fault section from the power distribution automation host apparatus 500 (i.e., the breaker 100 on / off signal, the switch 200 on / off signal). The terminal communication unit 480 transmits the control result of the circuit breaker 100 or the switch 200 according to the control signal to the power distribution master 500.

The terminal control unit 490 controls the breaker 100 or the switch 200 according to the control signal received through the terminal communication unit 480 to separate the fault section from the power distribution line. The terminal control unit 490 controls the breaker 100 or the switch 200 according to the control signal to recover the fault section. The terminal control unit 490 transmits the control result information according to the control signal (that is, the separation or recovery state to the distribution line) to the distribution automation master 500 through the terminal communication unit 480. [

As described above, the high-resistance ground fault 10 detection system using the distribution automation system according to the embodiment of the present invention detects the fault current before and after the fault differently from the conventional fault current detection method only, And a failure is judged by comparing the abnormal state after the failure. In the related art, when a breakdown is detected in the remote terminal device 400 of the switch 200 and the breaker 100 and is sent to the power distribution master 500, a fault is determined by the worker and a control command is issued to the master terminal. It was separated manually. However, according to the present invention, when the failure information before and after failure of the switch 200 and the breaker 100 is transmitted to the power distribution master device through the remote terminal device 400, To automatically determine whether a fault has occurred, and to automatically isolate a fault section. In the conventional art, the breaker 100 only blocks the breaker 100, and the breaker 200 manually separates the fault section. However, according to the present invention, the circuit can be automatically shut off when a fault occurs (up to about 500 A) have.

The power distribution master 500 determines whether the wire 20 is disconnected in each section of the power distribution line based on the fault resistance and normal resistance calculated based on the fault information received from the plurality of remote terminal apparatuses 400 . The power distribution master 500 transmits the control signal of the breaker 100 or the switch 200 of the section determined as the disconnection of the wire 20 to the corresponding remote terminal 400 to separate the fault section.

10, the power distribution master 500 includes a master communication unit 520, a pre-failure data collection unit 540, a failure determination unit 560, a power distribution control unit 580, a master output unit 590).

The master value communication unit 520 transmits and receives data to and from a plurality of remote terminal apparatuses 400. That is, the master value communication unit 520 receives the failure information from the plurality of remote terminal apparatuses 400. The master value communication unit 520 transmits a control signal for separating or restoring the fault section (i.e., the breaker 100 on / off signal, the switch 200 on / off signal). The master value communication unit 520 receives the control result of the breaker 100 or the switch 200 according to the control signal transmitted thereto.

The pre- and post-failure data collecting unit 540 detects and collects voltage, current, and phase before failure and voltage, current, and phase after failure from the failure information received through the master communication unit 520. [

The failure judgment unit 560 judges whether or not a fault has occurred in each section on the basis of the voltage, the current and the phase before failure, the voltage, the current and the phase after the failure collected by the data collecting unit 540 before and after the failure. To this end, the failure determination unit 560 calculates the pre-failure resistance (i.e., the normal resistance) using the voltage and current before the failure. The failure determination unit 560 calculates the post-failure resistance (i.e., the failure resistance) by using the voltage and current after the failure. 9 and 10 showing an A phase circuit between the 40th circuit breaker 100a and the 60th circuit breaker 200a, a method of calculating a resistance value for each section when the wire 20 is disconnected is described as an example The following is shown below. In this case, since the magnitude of the fault current varies depending on the ground fault type at the time of the ground fault (10), the ground fault (10; see FIG. 11) and the open fault (see FIG. 12) Explain.

Zline3 is the section line resistance, and Zload3 is the load resistance. 40 It is possible to measure the voltage and current at the circuit breaker 100a and calculate the resistance value between 40th to 60th. Therefore, the failure is judged by comparing the change of the resistance value between the pre-failure state and the post-failure state. The resistance value is calculated by dividing the measured current value by the voltage value measured by the No. 40 breaker 100a, and the resistance value is calculated by the 60th switch 200a in the same manner. Therefore, if the resistance value calculated in the No. 60 switch 200a is subtracted from the resistance value calculated in the No. 40 circuit breaker 100a, the interval resistance value can be calculated. In this case, the resistance values before and after the fault event are compared and calculated as follows.

First, the voltage measured at fault No. 40 is 13200 V, the current is 100 A, the phase angle is 25 degrees, the voltage of 60 before fault is 13000 V, the current is 50 A, and the phase angle is 30 degrees. The voltage measured at fault 40 is 13300 V, the current is 10 A, the phase angle is 60 degrees, the voltage measured at 60 after failure is 6000 V, the current is 20 A, and the phase angle is 230 degrees.

1) The resistance value before the occurrence of the failure event of No. 40 can be calculated as shown in Equation 1 below.

2) The resistance value before the occurrence of the failure event of No. 60 can be calculated as shown in the following formula (2).

3) The resistance value after the occurrence of the fault event in No. 40 can be calculated as shown in Equation 3 below.

4) The resistance value after the occurrence of the fault event of No. 60 can be calculated as shown in Equation (4) below.

5) The resistance value between No. 40 and No. 50 before the occurrence of the failure event can be calculated as shown in Equation (5) below.

6) The resistance value between No. 40 and No. 50 after the occurrence of the fault event can be calculated as shown in Equation (6) below.

The resistance values of A, B, and C at the normal time are similar to those between 40 and 60 before and after the fault event. However, since there is a difference in resistance between phases, it is a method to determine the failure by analyzing the change of R + jX value. When the resistance value before the occurrence of the failure event of Equation (5) is compared with the R + jX value after the occurrence of the failure event of Equation (6), the R value was varied from 300? To -3128.7 ?, and the X value varied from 520? To -4196?. Since the R value after the occurrence of the failure event can not be a theoretically negative value, the sound image is + R and + jX values when compared with the sound image, and when the failure images are -R, It is judged that the wire is broken. The distribution line configuration consists of the distributed power line and the general line, and the distributed power line is connected to the distribution line and the generator. Therefore, when the value measured at No. 60 is supplied from the load side to the power source side, Occurs. However, the voltage and current measured at 60 are zero because the energy is not supplied when the wire 20 is disconnected in a normal line. Therefore, there are two ways to determine the change in resistance for each section. First, there is a method of detecting the fault by comparing the polarity of the R + jX value for each section before and after the occurrence of the fault event, and a method of detecting the fault by comparing the resistance of the R + jX value for each section before and after the occurrence of the fault event. The method of setting the failure judgment reference value is calculated as the ratio of the resistance value of each phase before occurrence of the fault event to the occurrence of each phase. Before the occurrence of a fault event, the R + jX value of the faulty phase and that of the healthy phase are compared first to calculate the faulted phase unbalanced load, and the failure judgment reference value is set to be 1 to 10 times, , The failure judgment reference value is set to a default value 1.5 times the phase unbalance resistance ratio of the pre-failure failure phase and the healthy phase. Therefore, there are two methods to judge the failure when the fault event is greater than 1.5 times the phase unbalance resistance ratio and to determine the polarity of R + jX.

First, if the operation is judged by the resistance ratio, the R value is 1.38 and the X value is 1.48. Therefore, the resistance ratio after failure is 5.44 and the X value is 5.08, which is larger than the reference value. .

Second, when the polarity of R + jX is judged, the reference set value is "+", the X value is "+", the polarity value after failure is "-" and the X value is "-" It can be judged as a failure.

Table 1 below summarizes the calculation method of the A-phase unbalance resistance ratio before and after the occurrence of the above-described fault event of each section.

The fault determination unit 560 differs in the method of calculating the resistance value of the fault section according to the system state of the fault section. That is, there are differences in the number of the switches 200 installed in the distribution line depending on the system conditions. In other words, as shown in FIG. 13, two switchgear 200 may be installed in the section depending on the system condition of the distribution line, three switches may be installed as shown in FIG. 14, As shown in FIG. 15, four switches 200 may be installed. Therefore, the failure determination unit 560 generates a difference in the calculation method of the resistance value of the EKR in the system state of the failure section (that is, the number of installed switches 200). For example, when a resistance value is calculated in a section in which four failure switches 200 are installed, the resistance value can be calculated using the voltage and the current for each switch 200. When the switch 200 closest to the power supply side is shut off, all loads after the switch 200 are turned off. Therefore, in order to calculate the resistance value of the fault section, the resistance value of the switch 200 closest to the power supply side and the resistance value The resistance value of the fault section is calculated. In order to do so, the fault resistance and the normal resistance are calculated using the voltage and current values before and after the fault measured by the switch 200 and the breaker 100.

The failure determination unit 560 compares the difference between the calculated resistance value and the normal resistance value with the reference value to determine whether or not a failure has occurred in the corresponding interval. At this time, the failure determination unit 560 determines that a failure occurs in the corresponding interval because the difference value exceeds the reference value. Here, the failure determination unit 560 determines whether a failure has occurred in accordance with the disconnection state of the wire 20 in the corresponding section.

The power distribution controller 580 controls the breaker 100 or the switch 200 of the corresponding interval to generate a control signal for separating or recovering the corresponding interval when the failure detector 560 determines that a failure has occurred. That is, the power distribution control unit 580 generates on / off control signals for the circuit breaker 100 and the switch 200 of the corresponding interval (i.e., the failure interval) to remotely control the switch 200 and the breaker 100 And the fault section is automatically shut off, and the fault is recovered by transferring the healthy section to another line through the remote control.

The master value output unit 590 outputs the determination result of the failure determination unit 560 to the screen. That is, if the master value output unit 590 determines that a section has failed, the corresponding section information and the failure information such as voltage, current, and phase are displayed on the screen. The master value output unit 590 may display the control result of the breaker 100 or the switch 200 received through the master value communication unit 520 on the screen.

Hereinafter, the differences between the high-resistance ground fault 10 detection system and the conventional system using the distribution automation system according to the embodiment of the present invention will be described in detail with reference to the accompanying drawings. Figs. 16 and 17 are diagrams for explaining the difference between a distribution automation system and a conventional system according to an embodiment of the present invention when two types of ground fault 10 occur in a machining distribution line. Fig.

As shown in FIG. 16, when the ground fault 10 is generated by disconnecting the power line A between the No. 40 breaker 100a and the No. 60 breaker 200a, a ground fault current is generated. At this time, since ground resistance is formed differently according to the disconnection form of the wire 20 such as asphalt ground, tree ground, gravel ground, etc., ground fault current also occurs differently.

Since the conventional protection relay operates according to the magnitude of the current, the protective relay operates normally when a current exceeding the set value flows. The core of the present invention is a method of sensing the state of the wire 20 by detecting a change in the resistance of the distribution line regardless of the magnitude of the ground fault current. The resistance to the power line of the sensing section is less than about 100 Ω, and it changes by several thousand Ω or more when the wire 20 is disconnected. If the voltage and current such as the breaker 200 and the breaker 100 can be measured, the fault is detected by comparing the resistance of the power line with the state before the fault and the state after the fault.

In particular, although there is a protective relay operating according to the magnitude of the voltage of each voltage when the wire 20 is disconnected, there is a problem that it is not operated correctly because it is induced by the customer-side transformer depending on the system situation such as the distributed power supply. When the A-phase line 20 is disconnected in the system diagrams 40 to 60, the A voltage is induced by the receiver-side transformer after the No. 60, and the A-phase generates the reverse current differently from the BC-phase. Since the Zload3 load is supplied from A at this time, the voltage-current phase difference (&thetas;&thetas; in FIG. 17) exceeds ± 90 degrees when the VI vector of the wire 20 is disconnected at the 60th switch 200a. And is located on the second or third surface depending on the vector rotation direction. Accordingly, the voltage-current phase difference is measured for each phase in the switch 200 according to the section when the wire 20 is disconnected, and the change in the resistance value of the power distribution line is detected to detect the failure in the automation system.

Hereinafter, a method for detecting a high-resistance ground fault 10 using a distribution automation system according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. 18 is a diagram for explaining a method for detecting a high-resistance ground fault 10 using a distribution automation system according to an embodiment of the present invention.

First, the remote terminal device 400 collects voltage and current from the circuit breaker 100 and the switch 200 installed in each section of the distribution line (S110). Current transformers 180 and 280 and current transformers 180 and 280 are installed in the plurality of circuit breakers 100 and switches 200 to detect the power source voltage, the load voltage, and the current. The remote terminal apparatus 400 collects the detected voltage and current from the transformers and the current transformers 180 and 280 installed in the plurality of circuit breakers 100 and the switches 200, respectively.

The remote terminal device 400 sets the video current trigger set value, the video voltage trigger set value, and the no-voltage trigger set value (S120).

The remote terminal device 400 generates a video current trigger, a video voltage trigger, and a no-voltage trigger based on the collected voltage minus current. At this time, the remote terminal device 400 generates a video current trigger if the variation value of the discrete signal per sample time is larger than the video current trigger setting value, by dividing the size of the video current among the collected currents by the resolution. The remote terminal apparatus 400 generates a video voltage trigger if the variation value of the discrete signal per sample time is larger than the video voltage trigger set value by dividing the magnitude of the video voltage among the voltages of the respective phases received from the circuit breaker 100 or the switch 200 do. When the voltages of the three phases (i.e., the A phase, the B phase, and the C phase) fall below the no-voltage trigger set value, the remote terminal apparatus 400 determines that the voltage is zero in the voltage distribution system and generates the no-voltage trigger. If at least one trigger among at least one of the video current trigger, the video voltage trigger, and the voltage-free trigger is generated (S130; YES), the remote terminal apparatus 400 calculates the voltage, And calculates the angle (S140).

The remote terminal device 400 generates a fault event based on the voltage, current, and phase angle before and after the generation of the trigger. That is, the remote terminal apparatus 400 generates a failure event when the value calculated by the RMS calculating unit 440 exceeds the set value. When a failure event occurs (S150: YES), the remote terminal device 400 generates failure information including voltage, current, and phase angles before and after occurrence of the failure event (S160).

The remote terminal device (400) transmits the generated failure information to the power distribution master device (500). The power distribution master 500 calculates a fault resistance and a normal resistance based on the fault information received from the remote terminal 400 (S170).

The power distribution master 500 compares the difference between the calculated resistance value and the normal resistance value with the reference value to determine whether or not a failure has occurred in each section of the distribution line. At this time, the power distribution master 500 judges that a fault occurs in the corresponding section because the difference value exceeds the reference value. If a fault section occurs (S180: YES), the power distribution master 500 detects the fault section and outputs the fault section to the screen (S190).

The power distribution master 500 generates an on / off control signal for the switch 200 and the breaker 100 of the corresponding section in order to switch (disconnect) the fault section from the distribution line. The power distribution master 500 transmits the generated control signal to the remote terminal devices 400 installed in the circuit breaker 100 and the switch 200 of the failure section. Accordingly, each of the remote terminal devices 400 controls the breaker 100 and the switch 200 connected in accordance with the control signal to switch the fault section from the power line (S200).

As described above, the high-resistance ground fault 10 detection system and method using the distribution automation system detects the failure of the electric wire 20 by detecting the resistance change of the distribution line to detect the failure, It is possible to detect a high advantage regardless of the magnitude of a fault current when a high resistance ground fault 10 that can not be detected by a conventional protection device is detected.

In addition, the high-resistance ground fault 10 detection system and method using the distribution automation system can prevent the breaker 100 from interrupting the fault current by remote control for each interval in the power distribution master 500 when the high resistance ground fault 10 occurs, In addition, there is an effect that the breaker current can be cut off in the switch 200 as well.

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 many variations and modifications may be made without departing from the scope of the present invention. It will be understood that the invention may be practiced.

10: Ground fault 20: Wires
30: Ground 40: Open fault
50: breaker 55: load
60: Actuator 70: Distribution automation system
80: Remote Terminal Unit (RTU) 90: Worker
100: breaker 120: contact point
140: power side transformer 160: load side transformer
180: Current transformer 200: Actuator
220: Contact point 240: Power side transformer
260: load side transformer 280: current transformer
300: load 400: remote terminal device
410: video current trigger determination unit 420: video voltage trigger determination unit
430: voltage-free trigger determination unit 440: RMS calculation unit
450: Event setting unit 460: Event generating unit
470: Failure information output unit 480: Terminal communication unit
490: terminal control unit 500: power distribution master
520: master communication unit 540: before and after the failure data collecting unit
560: failure determination unit 580: distribution control unit

Claims (21)

A plurality of fault information generating means for generating fault information including a fault voltage and a phase voltage before and after occurrence of a fault event based on the fault voltage detected by the breaker or switch installed in each section of the distribution line divided into a plurality of sections, Remote terminal devices; And
Determining whether a wire is disconnected in each section of the distribution line based on fault resistance and normal resistance calculated on the basis of the fault information received from the plurality of remote terminal apparatuses and determining whether the disconnection of the circuit breaker or the switch And a power distribution master device for transmitting a control signal to the corresponding remote terminal devices to separate the fault sections. The method according to claim 1,
A plurality of power supply side transformers installed on the power supply side of the circuit breaker or the switch to detect the power supply voltage and transmit the voltage to the remote terminal installed in the circuit breaker or the switch;
A plurality of load side transformers installed on the load side of the circuit breaker or switches to detect the load side voltage and transmit the detected load side voltage to a remote terminal installed in the circuit breaker or the switch; And
Further comprising a current transformer installed at each of the load side of the breaker or the switch to detect the current and transmit the detected current to the remote terminal installed in the breaker or the switch. The method according to claim 1,
Wherein the power distribution automation master comprises:
Calculating a normal resistance by using a voltage and a current before occurrence of a failure event included in the failure information received from the plurality of remote devices and calculating a failure resistance by using a voltage and a current after occurrence of a failure event included in the failure information Wherein the ground fault detection system comprises: The method of claim 3,
Wherein the power distribution automation master comprises:
And judging that the electric line is disconnected in the corresponding section when the difference value of the calculated fault resistance and normal resistance exceeds the resistance set value. The method according to claim 1,
Wherein the power distribution automation master comprises:
If there are two switches in the section, the value obtained by subtracting the resistance value of the power switch from the resistance value of the load switch is calculated as the section resistance of the corresponding section,
When there are three or more switches in the interval, the value obtained by subtracting the resistance value of the power source side switch and the resistance value of the remaining load side switch at the largest resistance value among the resistance values of the load side switches is calculated as the interval resistance of the corresponding interval Fault ground fault detection system using distributed automation system. The method according to claim 1,
Wherein the power distribution automation master comprises:
A fault signal is transmitted to a remote terminal of a breaker installed in a section determined as a fault occurrence, and a normally open breaker is inserted into a healthy section to recover a power failure. system. The method of claim 6,
Wherein the power distribution automation master comprises:
And when the current measured by the switch is less than the load current openable / closable current, the open / close state of the corresponding section is maintained. The method according to claim 1,
The remote terminal apparatus comprises:
A video current trigger determination unit for generating a video current trigger when the variation value of the discrete signal per sample time exceeds a set value by dividing the magnitude of the video current among the currents by the resolution,
A video voltage trigger determination unit for generating a video voltage trigger when the variation value of the discrete signal per sample time exceeds the set value by dividing the magnitude of the video voltage among the voltages by the resolution,
A non-voltage trigger determination unit for generating a non-voltage trigger when the voltages of the three phases are all below the no-voltage trigger set value;
An RMS calculating unit for calculating a voltage, a current, and a phase angle before and after the trigger generation when at least one trigger among the image current trigger, the image voltage trigger, and the no-voltage trigger occurs;
An event generating unit for comparing a voltage, a current, and a phase angle before and after a trigger generated by the RMS calculating unit with a reference value to generate a fault event; And
And a failure information output unit for generating failure information including a voltage, a current, and a phase angle before and after the trigger occurrence, when the failure event occurs in the event generation unit, and transmitting the generated failure information to the power distribution automation main controller High - Resistance Ground Fault Detection System Using System. The method of claim 8,
The remote terminal apparatus comprises:
And a terminal controller for controlling the breaker and the switch according to a control signal received from the power distribution master device to recover a fault section. The method according to claim 1,
Wherein the power distribution automation master comprises:
A fault pre-and-post data collecting unit for detecting and storing voltage, current and phase angles before and after the fault in the fault information received from the plurality of remote terminal devices;
A failure determination unit for determining whether a failure has occurred in each section of the distribution line based on the voltage, current, and phase angle before and after the failure collected in the before and after-failure data collection unit;
A distribution controller for transmitting a breaker for separating a period determined as a failure in the failure determination unit and a switch control signal to a remote terminal device in a failure interval; And
And a master value output unit for outputting information on an interval determined as a failure by the failure determination unit and failure information. The method of claim 10,
Wherein the failure determination unit
Wherein the failure resistance and the normal resistance are calculated on the basis of the voltage and the current before and after the failure, and when the variation value of the failure resistance and the normal resistance exceeds the reference value, High resistance ground fault detection system. Collecting voltages and currents of a plurality of breakers and switches provided in each section of the distribution line;
Generating a fault event based on the collected voltage and current;
Generating fault information including a voltage, a current, and a phase angle before and after a fault event when a fault event occurs in the fault event;
Calculating a fault resistance and a normal resistance based on the generated fault information;
Determining whether a fault has occurred in each section of the distribution line based on the calculated fault resistance and normal resistance; And
And a step of separating the fault section from the power distribution line by controlling the breaker and the switch provided in the fault section determined as the occurrence of the fault in the step of determining whether or not the fault has occurred, . The method of claim 12,
The step of collecting the voltage and current comprises:
Detecting the voltage on the power source side for each of the breakers or the power source side of the breaker;
Detecting a load-side voltage on each side of the load side of the breaker or switch; And
And detecting a current for each phase at the load side of the breaker or the switch. The method of claim 12,
Wherein the step of calculating the fault resistance and the normal resistance comprises:
Calculating normal resistance using voltage and current before occurrence of a failure event included in the failure information received from the plurality of remote devices; And
And calculating a fault resistance using a voltage and a current after occurrence of a fault event included in the fault information. The method of claim 12,
In the step of calculating the fault resistance and the normal resistance,
If there are two switches in the section, the value obtained by subtracting the resistance value of the power switch from the resistance value of the load switch is calculated as the section resistance of the corresponding section,
When there are three or more switches in the interval, the value obtained by subtracting the resistance value of the power source side switch and the resistance value of the remaining load side switch at the largest resistance value among the resistance values of the load side switches is calculated as the interval resistance of the corresponding interval A method for detecting a high resistance ground fault using a power distribution automation system. The method of claim 12,
In the step of determining whether the failure has occurred,
And if the difference between the calculated fault resistance and the normal resistance exceeds the resistance set value, it is determined that the electric line is broken in the corresponding section. The method of claim 12,
The step of separating the fault section from the distribution line includes:
Transmitting a trip signal to a remote terminal device of a breaker and a breaker installed in a section determined as a failure occurrence; And
And recovering the power failure by injecting a normally open breaker into the healthy section. 18. The method of claim 17,
The step of separating the fault section from the distribution line includes:
And if the current measured by the switch is less than the load current openable and closable current, maintaining the cutoff state of the corresponding section. The method of claim 12,
Wherein the step of generating the fault event comprises:
Generating a video current trigger when the variation value of the discrete signal per sample time exceeds the set value by dividing the magnitude of the video current among the currents by the number of resolutions;
Generating a video voltage trigger when the variation value of the discrete signal per sample time exceeds a set value by dividing the magnitude of the video voltage among the voltages by the resolution,
Generating a no-voltage trigger if all three voltages are below a no-voltage trigger setpoint;
Calculating at least one of voltage, current, and phase angle before and after the trigger generation if at least one trigger occurs between the video current trigger, the video voltage trigger, and the no-voltage trigger; And
And comparing the calculated voltage, current, and phase angle before and after the trigger with a reference value to generate a fault event. The method of claim 12,
Further comprising the step of outputting information on a fault zone determined as a fault occurrence and fault information in the step of determining whether the fault has occurred or not. The method of claim 12,
In the step of determining whether the failure has occurred,
And when the variation value of the fault resistance and the normal resistance exceeds a reference value, it is determined that a fault has occurred in the corresponding section.

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