WO2023221431A1

WO2023221431A1 - System and method for finding fault in power distribution line

Info

Publication number: WO2023221431A1
Application number: PCT/CN2022/132363
Authority: WO
Inventors: 刘红文; 杨金东; 陈虓; 杨文呈; 黄继盛; 李凯恩; 陈饶; 罗文军
Original assignee: 云南电网有限责任公司临沧供电局
Priority date: 2022-05-17
Filing date: 2022-11-16
Publication date: 2023-11-23
Also published as: CN114814465A; CN114814465B

Abstract

Provided in the present application are a system and method for finding a fault in a power distribution line. The system comprises a detection sensor, a mechanical arm, a receiving apparatus and a single-phase switch. The single-phase switch is provided on each phase of electric wire of a power distribution line, so as to control the turning-on and turning-off of each phase of line of the power distribution line. When a fault occurs, the single-phase switch is turned off; a first wiring end and a second wiring end of the mechanical arm are connected to two sides of the single-phase switch, and a starting switch of the mechanical arm is turned on, such that the line of the power distribution line generates a zero-sequence voltage. The detection sensor is connected to the power distribution line, the zero-sequence voltage is measured by means of the detection sensor, and the zero-sequence voltage is received by means of the receiving apparatus. By means of analyzing zero-sequence voltages at different positions, whether a single-phase fault occurs and the position where the fault occurs are determined. By means of the system and method for finding a fault in a power distribution line, which system and method are provided in the present application, the position where a single-phase fault occurs can be accurately and quickly found, thereby improving the fault processing efficiency.

Description

A distribution line fault finding system and method

This application claims priority to the Chinese patent application filed with the China Patent Office on May 17, 2022, with the application number 202210540729.2 and the invention title "A distribution line fault finding system and method", the entire content of which is incorporated by reference. in this application.

Technical field

The present application relates to the technical field of distribution network fault detection, and in particular to a distribution line fault finding system and method.

Background technique

The power system can be divided into high current grounding system and small current grounding system according to the grounding treatment method. In small current grounding systems, single-phase grounding is a common temporary fault, which often occurs in humid and rainy weather. However, after a single-phase grounding occurs, the faulted phase-to-ground voltage decreases and the phase voltages of the non-faulted two phases increase, but the line voltage remains symmetrical. Therefore, a single-phase ground fault does not affect the continuous power supply to users, and the system can operate for 1 to 2 hours.

Therefore, when a single-phase ground fault occurs, the power system can still continue to provide power to users. However, due to the long-term operation of the power system at this time, the voltage of the non-faulty two phases increases, which may cause the weak link of the insulation to be broken down. As a result, a phase-to-phase short circuit develops, causing the accident to expand. It may also damage the equipment and undermine the safe operation of the system.

In order to ensure the safe operation of the system, distribution automation and insulation meggers are usually used to locate faults. However, distribution automation can only isolate faults within a certain distance and cannot give a specific fault point; an insulation megger is used to measure ground insulation, but due to capacity limitations, the fault point is difficult to find. Therefore, maintenance personnel often cannot find the fault point, which prolongs the troubleshooting time, resulting in low efficiency of troubleshooting.

Contents of the invention

This application provides a distribution line fault finding system and method to solve the problem of low efficiency in fault processing due to the failure to find the fault point and prolonging the fault processing time.

In a first aspect, this application provides a distribution line fault finding system, including: a detection sensor, a robotic arm, a receiving device and a single-phase switch, wherein: the detection sensor is connected to the distribution line, and the detection sensor is used to detect all The zero-sequence voltage of the distribution line; the detection sensor includes a communication module, and the communication module is used to send the zero-sequence voltage; the single-phase switch is arranged on each phase wire of the distribution line, and the single-phase The switch is configured to open the single-phase switch when a fault occurs on the distribution line; the mechanical arm includes a start switch, a first terminal and a second terminal, and the start switch is connected to the first terminal. The first terminal and the second terminal are connected in series, and the first terminal and the second terminal are used to short-circuit the single-phase switch; the mechanical arm is configured to connect the third terminal when a fault occurs on the distribution line. A terminal and the second terminal are short-circuited on both sides of the single-phase switch, and the starting switch is closed to generate the zero-sequence voltage; the receiving device is communicatively connected to the communication module to receive the The zero sequence voltage sent by the communication module. Through the mechanical arm and the receiving device, the zero sequence voltage in the line is obtained. By analyzing the zero sequence voltage, it can be determined whether there is a single-phase fault in the line. If there is a single-phase fault, the fault location is determined based on the zero-sequence voltage value, thereby improving the efficiency of fault handling.

In some embodiments, the detection sensor is a three-phase sensor, each phase of the detection sensor is connected to the communication module, each phase of the detection sensor includes a coupling capacitor, the detection sensor includes a measurement impedance, and the coupling A capacitor is connected in series with the measurement impedance to detect the zero sequence voltage. The zero sequence voltage is more accurately measured based on the measured impedance, improving the accuracy of the system.

In some embodiments, the communication module is a signal transmitting antenna, and the receiving device includes a signal receiving antenna. The signal transmitting antenna and the signal receiving antenna are used to transmit the zero sequence voltage in the form of electromagnetic waves. The zero-sequence voltage is transmitted in the form of electromagnetic waves, which is fast and does not require a medium.

In some embodiments, the receiving device includes a receiving unit and a processing unit, and the receiving unit is communicatively connected with the communication module. The processing unit is connected to the receiving unit, and the processing unit is configured to analyze the zero-sequence voltage to more conveniently process the zero-sequence voltage.

In some embodiments, the processing unit is further configured to, if the zero-sequence voltage of one phase in the distribution line is not equal to the other two phases, obtain the position of the minimum value of the zero-sequence voltage in the phase, to Improve the accuracy of finding fault locations.

In some embodiments, the system further includes an alarm unit, the alarm unit is connected in parallel with the single-phase switch, and the alarm unit is configured to send an alarm signal when a fault occurs on the distribution line. This ensures that when a fault occurs, maintenance personnel can be promptly reminded for maintenance.

In some embodiments, the detection sensor is provided with an adapted waterproof housing. The waterproof housing can prevent the detection sensor from being eroded by rainwater, thereby extending the service life of the detection sensor.

In the second aspect, this application provides a distribution line fault finding method, including:

When the distribution line fails, the single-phase switch is disconnected; connect the first terminal and the second terminal of the robotic arm to both sides of the single-phase switch for each phase of the distribution line, and close the starting switch so that The lines of the distribution line generate zero sequence voltage; detect the zero sequence voltage through detection sensors; send the zero sequence voltage through the communication module; receive the zero sequence voltage through the receiving device to determine whether there is a single-phase fault; if there is In the case of a single-phase fault, the fault point location is determined based on the zero sequence voltage.

In some embodiments, determining whether a single-phase fault exists includes: analyzing the zero-sequence voltage through a zero-sequence voltage function, where the zero-sequence voltage function is

Among them, _U If each phase in the distribution line

If the values of are equal, there is no single-phase fault; if each phase in the distribution line

If the values are not equal, there is a single-phase fault.

In some embodiments, determining the location of the fault point includes: screening the distribution line with the other two phases.

The target phase whose values are not equal; obtain the position of the i-th detection sensor when the value of i in the target phase U _X0i is the smallest.

It can be seen from the above technical solution that the present application provides a distribution line fault finding system and method, which controls the opening and closing of the distribution line through the single-phase switch. When a fault occurs, the single-phase switch is disconnected to protect the line safety. After connecting the first terminal and the second terminal of the robotic arm to both sides of the single-phase switch of each phase of the distribution line, the start switch is closed to generate a zero-sequence voltage in the distribution line. One end of the detection sensor is connected to the distribution line and the other end is grounded. The detection sensor measures the zero sequence voltage and receives the zero sequence voltage through the receiving device. By analyzing the zero-sequence voltage values at different locations and different phases, it is determined whether there is a single-phase fault. If there is a single-phase fault, analyze the zero sequence voltage value to determine the fault location. This application provides a distribution line fault finding system and method that can determine whether there is a single-phase fault in the line, and can find the location of the single-phase fault more accurately and quickly, thereby reducing fault processing time and improving fault processing efficiency. efficiency.

Description of the drawings

Figure 1 is a schematic structural diagram of a distribution line fault finding system of the present application;

Figure 2 is a schematic structural diagram of a receiving device in an embodiment of the present application;

Figure 3 is a schematic structural diagram of the alarm unit in the embodiment of the present application;

Figure 4 is an example diagram of a distribution line fault finding system method provided by an embodiment of the present application;

Figure 5 is a flow chart of a distribution line fault finding method in an embodiment of the present application.

Detailed ways

An embodiment will be described in detail below, examples of which are illustrated in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings refer to the same or similar elements unless otherwise indicated. The implementations described in the following examples do not represent all implementations consistent with this application. are merely examples of systems and methods consistent with aspects of the application as detailed in the claims.

Small current grounding system refers to a three-phase system in which the neutral point is not grounded or is grounded through an arc suppression coil and high impedance. It is also called a neutral point indirect grounding system. When a ground fault occurs in a certain phase, since a short circuit cannot be formed, the ground fault current is often much smaller than the load current, so this system is called a small current grounding system.

Single-phase grounding is a common temporary fault in low-current grounding systems. Single-phase ground fault is the most common fault in power distribution system, which often occurs in humid and rainy weather. It is mainly caused by many factors such as tree obstacles, single-phase breakdown of insulators on distribution lines, single-phase wire breakage, and small animal hazards. Single-phase grounding not only affects the user's normal power supply, but may also produce overvoltage, burn out equipment, or even cause a phase-to-phase short circuit to expand the accident. Therefore, how to quickly find the fault location and handle the fault in a timely manner is crucial.

However, the most commonly used methods for locating faults are distribution automation and insulation meggers. Distribution automation refers to the comprehensive use of computer, information and communication technologies based on the primary grid and equipment of the distribution network, and through information integration with related application systems to achieve monitoring, control and rapid fault isolation of the distribution network. , providing real-time data support for the power distribution management system. However, distribution automation can only isolate faults within a certain distance and cannot give specific fault points. Insulation megger is a measuring instrument commonly used by electricians. It is mainly used to check the insulation resistance of electrical equipment, household appliances or electrical lines to ground and between phases. However, the use of insulation meggers for ground insulation measurement is limited by capacity, making it difficult to find fault points. Therefore, maintenance personnel often cannot find the fault point, which prolongs the troubleshooting time, resulting in low efficiency of troubleshooting.

In order to solve the above problems, this application provides a distribution line fault finding system, see Figure 1 , including: a detection sensor 1, a robotic arm 2, a receiving device 3 and a single-phase switch 4. Wherein, the single-phase switch 4 is provided on each phase wire of the distribution line, and the single-phase switch 4 is used to control the on/off of the line. One end of the detection sensor 1 is connected to the distribution line, and the other end is grounded, and is used to detect the zero sequence voltage of the distribution line. The detection sensor 1 also includes a communication module 13 , which is communicatively connected with the receiving device 3 . The communication module 13 is used to send zero sequence voltage to the receiving device 3 . The robot arm 2 includes a start switch 23, a first terminal 21 and a second terminal 22. The start switch 23 is connected in series with the first terminal 21 and the second terminal 22. The start switch 23 is used to control the on and off of the robot arm 2 , and the first terminal 21 and the second terminal 22 are used to short-circuit the single-phase switch 4 .

Wherein, the single-phase switch 4 is configured to open when a fault occurs in the distribution line. After the single-phase switch 4 on the distribution line is disconnected, the circuit of the distribution line is disconnected to protect the line. It should be noted that the distribution lines in the embodiments of this application are all three-phase high-voltage wires.

In some embodiments, the single-phase switch 4 may be a single-phase sectional protection switch commonly installed on the line. Therefore, when the single-phase switch 4 is open, it means that a ground fault has occurred in the distribution line. At this time, the fault should be dealt with promptly.

During the process of troubleshooting, the first terminal 21 and the second terminal 22 of the robot arm 2 are connected to both sides of the single-phase switch 4 . After confirming that the connection positions of the first terminal 21 and the second terminal 22 are correct, close the start switch 23 of the robot arm 2 . At this time, the robot arm 2 restores the power distribution line to the path state. It is equivalent to using the robotic arm 2 to continue to supply voltage to the line, so that the line of the distribution line generates zero sequence voltage. Since the detection sensor 1 is connected to the distribution line, the detection sensor 1 can detect the zero sequence voltage generated in the line at this time. After detecting the zero sequence voltage, the detection sensor 1 sends the zero sequence voltage to the receiving device 3 through the communication module 13 . Referring to FIG. 2 , the receiving device 3 includes a receiving unit 31 and a processing unit 32 , and the receiving unit 31 and the processing unit 32 are connected. The zero-sequence voltage is received through the receiving unit 31, and the zero-sequence voltage is analyzed through the processing unit 32 to determine whether there is a single-phase fault in the line. If there is a single-phase fault, the zero-sequence voltage is analyzed by the processing unit 32 to determine the location of the fault.

In some embodiments, the communication module 13 uses a signal transmitting antenna, and the receiving unit 31 uses a signal receiving antenna. Antennas are an indispensable part of wireless transmission. In addition to using optical fibers, cables, network cables, etc. to transmit wired signals, any signal that uses electromagnetic waves to propagate in the air requires various forms of antennas. The signal transmitting antenna and the signal receiving antenna of this application can be selected according to the actual situation. The signal transmitting antenna and the signal receiving antenna transmit zero-sequence voltage in the form of electromagnetic waves, which have the advantages of fast transmission and no need for media. The signal transmitting antenna and the signal receiving antenna are small in size and occupy a small area, making the receiving device more portable.

In some embodiments, the processing unit 32 is configured to obtain the position of the minimum value of the zero sequence voltage in one phase of the distribution line if the zero sequence voltage is not equal to the other two phases. For example: the three phases of the distribution line are phase A, phase B, and phase C. Suppose the sum of the zero sequence voltage values measured by all detection sensors 1 on phase A is X; the zero sequence voltage measured by all detection sensors 1 on phase B is The sum of the sequence voltage values is Y; the sum of the zero sequence voltage values measured by all detection sensors 1 on the C phase is Z; if A=B≠C, then there is a single-phase fault in the C phase, and the lowest zero sequence voltage detected in the C phase is obtained The value is the position of sensor 1, which is the position closest to the fault point. This allows the fault location to be determined more accurately during the fault finding process.

In some embodiments of the present application, see FIG. 3 , in order to promptly remind maintenance personnel that there is a single-phase fault in the line, the system also includes an alarm unit 5 , and the alarm unit 5 is connected in parallel with the single-phase switch 4 . The alarm unit 5 is configured so that when a fault occurs, the alarm unit 5 can send out an alarm signal in time. The alarm signal can take many forms. For example, the alarm unit 5 can use an acoustic alarm. When the single-phase switch 4 is disconnected, the acoustic alarm can play voice prompts or music prompts to remind maintenance personnel to deal with the fault in time; or The alarm unit 5 can adopt a magnetic switch alarm, a vibration alarm, an ultrasonic alarm, etc. After receiving the alarm signal from the alarm unit 5, the maintenance personnel turn off the alarm unit 5 and perform troubleshooting work in a timely manner.

In some embodiments of the present application, the detection sensor 1 is a three-phase sensor. Each phase of the three-phase sensor includes a coupling capacitor 11 and a measurement impedance 12 . Coupling capacitance, also known as electric field coupling or electrostatic coupling, is a coupling method caused by the existence of distributed capacitance. The coupling capacitor couples and isolates the two systems of strong current and weak current through the capacitor, provides a high-frequency signal path, prevents low-frequency current from entering the weak current system, and ensures personal safety. The measurement impedance 12 can be either a resistance or an inductance. Suppose the impedance of the measured impedance 12 is Z, then Z is usually

0.01~0.0001 times. By measuring the impedance 12, the zero sequence voltage value in the line can be measured more accurately.

In some embodiments, the detection sensor 1 is provided with an adapted waterproof housing. Since the detection sensor 1 is installed outdoors, it may be contaminated by rain, dew, etc., resulting in oxidation reaction and shortened service life. In order to prevent the detection sensor 1 from being corroded, the detection sensor 1 is provided with a waterproof shell to extend the service life of the detection sensor 1 . For example, a waterproof shell made of polycarbonate can be used, which has good waterproof performance, excellent electrical properties, and strong impact resistance.

Refer to Figure 5, which is a flow chart of a distribution line fault finding method in an embodiment of the present application. This application also provides a distribution line fault finding method corresponding to the above system, as shown in Figure 5, including the following steps:

S100: When a fault occurs in the distribution line, the single-phase switch 4 is disconnected;

S200: Connect the first terminal 21 and the second terminal 22 to both sides of the single-phase switch 4 of each phase of the distribution line, and close the starting switch 23 so that the distribution line generates zero sequence voltage;

S300: Detect zero sequence voltage through detection sensor 1;

S400: Send the zero sequence voltage through the communication module 13;

S500: Receive the zero sequence voltage through the receiving device 3 to determine whether there is a single-phase fault;

S600: If there is a single-phase fault, determine the location of the fault point based on the zero sequence voltage.

It can be seen that in the distribution line fault finding method provided in the embodiment of the present application, when a fault occurs in the line, the single-phase switch 4 is turned off to protect the safety of the line. By connecting the first terminal 21 and the second terminal 22 of the robot arm 2 to both sides of the single-phase switch 4, the path state of the line is restored. At this time, it is equivalent to continuing to provide voltage to the line, and the power supply will stimulate the fault location to generate zero sequence voltage. The zero sequence voltage is measured by the detection sensor 1 connected to the distribution line, and the zero sequence voltage is sent to the receiving device 3 through the communication module 13 . After receiving the zero-sequence voltage, the receiving device 3 can determine whether there is a single-phase ground fault by analyzing the zero-sequence voltages at different locations. If there is a single-phase ground fault, the fault location is determined by analyzing the zero sequence voltage.

Among them, _U If each phase in the distribution line

If the values are not equal, there is a single-phase fault.

In some embodiments, determining the location of the fault point includes: screening the target phase in the distribution line that is not equal to the value of the other two phases; obtaining the position of the i-th detection sensor when the value of i is the smallest in the target phase .

For example: See Figure 4, which is an example diagram of a distribution line fault finding method provided by an embodiment of the present application. When the single-phase switch 4 of the distribution line is disconnected, connect the first terminal 21 and the second terminal 22 of the robot arm 2 in parallel to both ends of the A-phase single-phase switch 4, start the switch 23, and detect the sensor 1 to obtain the A-phase Zero-sequence voltage distribution U _A0 ; then connect the first terminal 21 and the second terminal 22 of the robot arm 2 in parallel to both ends of the B-phase single-phase switch 4, start the switch 23, and detect the sensor 1 to obtain the B-phase zero-sequence voltage distribution U _B0 ; then when the first terminal 21 and the second terminal 22 of the robot arm 2 are connected in parallel to both ends of the C-phase single-phase switch 4, the switch 23 is started, and the detection sensor 1 obtains the B-phase zero sequence voltage distribution U _C0 . If there are n detection sensors 1 in phase A, the zero sequence voltage of each detection sensor 1 is U _A0i , i is 1 to n; if there are n detection sensors 1 in phase B, the zero sequence voltage of each detection sensor 1 is U _B0i , i ranges from 1 to n; if C phase U _C0 has n detection sensors 1, the zero sequence voltage of each detection sensor 1 is U _C0i , i ranges from 1 to n. but,

The phase A zero sequence voltage sum function is

The B-phase zero sequence voltage sum function is

The C phase zero sequence voltage sum function is

For example, the function values of phases A, B, and C are all equal, that is

then there is no single-phase ground fault on the line; if two of them are not equal

Then phase B fails. At this time, the B-phase zero sequence voltage is analyzed. When U _B0i is the minimum value, the value of i is used to obtain the position of the i-th sensor, that is, the position of the i-th sensor is the position closest to the fault point.

It can be seen from the above technical solution that the present application provides a distribution line fault finding system and method, which controls the opening and closing of the distribution line through the single-phase switch 4 . When a fault occurs in the line, the single-phase switch 4 is turned off, and the alarm unit 5 simultaneously sends out an alarm signal. After receiving the alarm signal, the maintenance personnel connect the first terminal 21 and the second terminal 22 of the robot arm 2 to both sides of the single-phase switch 4 of each phase of the distribution line, and close the start switch 23 . At this time, the robot arm 2 restores the path state of the line, causing the line to generate zero sequence voltage. The detection sensor 1 measures the zero sequence voltage by connecting to the distribution line, and sends the zero sequence voltage to the receiving device 3 through the communication module 13 . After receiving the zero-sequence voltage, the receiving device 3 determines whether a single-phase fault occurs by analyzing the magnitude of the zero-sequence voltage at different locations. If a single-phase fault occurs, the location of the fault can be determined based on the zero-sequence voltage value. This application provides a distribution line fault finding system and method that can more accurately and quickly find the location of a single-phase fault, thereby reducing fault processing time and improving fault processing efficiency.

Claims

A distribution line fault finding system, characterized by including: a detection sensor, a mechanical arm, a receiving device and a single-phase switch, wherein:

The detection sensor is connected to the distribution line, and the detection sensor is used to detect the zero-sequence voltage of the distribution line; the detection sensor includes a communication module, and the communication module is used to send the zero-sequence voltage;

The single-phase switch is provided on each phase wire of the distribution line, and the single-phase switch is configured to open when a fault occurs on the distribution line;

The mechanical arm includes a start switch, a first terminal and a second terminal. The start switch is connected in series with the first terminal and the second terminal. The first terminal and the second terminal are connected with each other. When the single-phase switch is short-circuited; when the distribution line fails, the robotic arm is configured to short-circuit the first terminal and the second terminal to both sides of the single-phase switch and close all the starting switch to generate the zero sequence voltage;

The receiving device is communicatively connected with the communication module to receive the zero sequence voltage sent by the communication module.
The distribution line fault finding system according to claim 1, wherein the detection sensor is a three-phase sensor, each phase of the detection sensor is connected to the communication module, and each phase of the detection sensor includes a coupling capacitor. , the detection sensor includes a measurement impedance, and the coupling capacitor is connected in series with the measurement impedance to detect the zero sequence voltage.
The distribution line fault finding system according to claim 1, wherein the communication module is a signal transmitting antenna, the receiving device includes a signal receiving antenna, and the signal transmitting antenna and the signal receiving antenna are used to The zero sequence voltage is transmitted in the form of electromagnetic waves.
The distribution line fault finding system according to claim 1, characterized in that the receiving device includes a receiving unit and a processing unit, the receiving unit is communicatively connected with the communication module, and the processing unit is connected with the receiving unit. connected, the processing unit is configured to analyze the zero sequence voltage.
The distribution line fault finding system according to claim 4, wherein the processing unit is configured to analyze the zero sequence voltage, including:

If the zero-sequence voltage of one phase in the distribution line is not equal to the other two phases, the position of the minimum value of the zero-sequence voltage in the phase is obtained.
The distribution line fault finding system according to claim 1, characterized in that the system further includes an alarm unit, the alarm unit is connected in parallel with the single-phase switch, and the alarm unit is configured to When a line failure occurs, an alarm signal is sent.
The distribution line fault finding system according to claim 1, wherein the detection sensor is provided with an adapted waterproof housing.
A method for finding faults in distribution lines, which is characterized by including:

When a distribution line fault occurs, the single-phase switch opens;

Connect the first terminal and the second terminal of the robotic arm to both sides of the single-phase switch of each phase of the distribution line, and close the starting switch to generate a zero-sequence voltage in the distribution line;

Detect the zero sequence voltage through a detection sensor;

Send the zero sequence voltage through the communication module;

Receive the zero sequence voltage through a receiving device to determine whether there is a single-phase fault;

If there is a single-phase fault, the fault point location is determined based on the zero sequence voltage.
The distribution line fault finding method according to claim 8, characterized in that the determining whether there is a single-phase fault includes:

The zero sequence voltage is analyzed through a zero sequence voltage function, which is

Among them, U

If each phase in the distribution line
If the values are equal, there is no single-phase fault;

If each phase in the distribution line
If the values are not equal, there is a single-phase fault.
The distribution line fault finding method according to claim 9, characterized in that the determining the location of the fault point includes:

Screen the distribution line with the other two phases
Target phases whose values are not equal;

Obtain the position of the i-th detection sensor when U X0i is the smallest value of i in the target phase.