Device and method for fault location of 10kV overhead line of distribution network

Abstract

The invention discloses a device and a method for fault location of a 10kV overhead line of a distribution network. The device comprises a test assembly for generating a special frequency detection signal; the receiving component is used for receiving information; the detection assembly is used for detecting the intensity of a special frequency signal on the line; the transmitting assembly is used for injecting the special-frequency detection signal into a to-be-detected line; and the grounding assembly is used for forming a signal loop. The method does not need to depend on complex and high-price equipment such as robot inspection and high-precision positioning, equipment dependency and maintenance cost are reduced, and the problems that in the prior art, equipment dependency is high, maintenance is tedious, and reliability is low in the severe environment are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of overhead line fault location, in particular to a device and method for fault location of 10kV overhead line of distribution network. BACKGROUND

[0002] In the field of fault location of 10kV overhead line of distribution network, the main methods are fault indicator method, traveling wave positioning method and impedance method, etc. The fault indicator method indicates the fault interval by detecting the sudden change of line current or voltage, and is usually installed at the key nodes of the tower or line. The traveling wave positioning method calculates the fault location by detecting the time difference of traveling wave head propagation based on the propagation characteristics of transient traveling wave generated by fault. The impedance method determines the fault point position by measuring and calculating based on the change of line impedance parameters before and after fault.

[0003] However, the fault indicator can only roughly determine the line section where the fault occurs, and cannot accurately locate the specific fault point. It is also easily affected by factors such as line load fluctuation and electromagnetic interference, resulting in misjudgment. Although the traveling wave positioning method has high theoretical positioning accuracy, it is affected by traveling wave attenuation, reflection and dynamic changes of line parameters, resulting in large actual positioning error. In addition, it requires the cooperation of multiple terminal devices, which not only has high deployment cost, but also requires strict time synchronization accuracy. The impedance method is greatly disturbed by the complex topology structure, distributed parameters and changes of grounding resistance of the distribution network line, making it difficult to ensure the positioning accuracy, especially in high resistance grounding fault scenarios. SUMMARY

[0004] Therefore, the technical problem to be solved by the present application is that the existing fault location technology is easily affected by factors such as line load fluctuation and electromagnetic interference, resulting in misjudgment.

[0005] The above technical problem is solved by the following technical solution: the present application proposes a device for fault location of 10kV overhead line of distribution network, which comprises: a test component for generating a special frequency detection signal; a receiving component for receiving information; a detection component for detecting the strength of the special frequency signal on the line; a transmitting component for injecting the special frequency detection signal into the line to be tested; a grounding component for forming a signal loop; The test component is connected to the transmitting component, the transmitting component is used for detachable connection with the line to be tested to realize signal injection, the grounding component cooperates with the test component and the ground to form a complete signal loop, the detection component can move along the line to be tested to collect the strength of the special frequency signal along the line, and the receiving component is in communication connection with the test component and the detection component respectively, and is used for receiving the signal data of the detection component and synchronizing the working state information of the test component.

[0006] In a preferred mode of the device for fault location of 10kV overhead line of distribution network, the test component comprises a host computer, a transmitting antenna arranged on one side of the host computer, and a test line arranged on one end of the host computer.

[0007] In a preferred mode of the device for fault location of 10kV overhead line of distribution network, the receiving component comprises a handheld piece and a receiving antenna, and the transmitting antenna is matched with the receiving antenna.

[0008] In a preferred mode of the device for fault location of 10kV overhead line of distribution network, the detection component comprises a detection clamp for clamping the line, and a detection rod connected with the detection clamp. The detection clamp is used for capturing the special frequency signal on the line, and the detection rod is used for supporting the detection clamp and transmitting the detection signal.

[0009] In a preferred mode of the device for fault location of 10kV overhead line of distribution network, the transmitting component comprises an injection clamp for clamping the line, and an injection rod connected with the injection clamp. The injection clamp is connected with the test line, and is used for injecting the special frequency detection signal generated by the test component into the line to be tested.

[0010] In a preferred mode of the device for fault location of 10kV overhead line of distribution network, when the grounding component is inserted into the ground, the current is introduced into the ground, so as to build a return path of the special frequency detection signal.

[0011] In a preferred mode of the micro machine for fault location of 10kV overhead line of distribution network, the test line is a shielded cable, which is used for connecting the host computer and the injection clamp, and guarantees stable transmission of the special frequency detection signal.

[0012] The application further provides a method for fault location of 10kV overhead line of distribution network, which comprises the following steps: A transmission loop of the special frequency detection signal is built, so that the special frequency detection signal can propagate in the line to be tested; The line to be tested is continuously injected with the preset special frequency detection signal; The signal strength information of the special frequency signal at different positions along the line to be tested is collected, so as to form signal strength distribution data; Based on the change characteristics of the signal strength distribution data, the fault position of the line to be tested is located.

[0013] In a preferred embodiment of the method for fault location of 10kV overhead lines in distribution networks according to the present invention: during the process of collecting special frequency signal strength information, the collection trajectory can be adjusted according to the line layout to ensure coverage of the key areas of the line under test; The variation characteristics of the signal strength distribution data include abrupt changes, attenuation, or interruption of signal strength, which are used to distinguish normal line segments from faulty line segments.

[0014] In a preferred embodiment of the method for fault location of 10kV overhead lines in distribution networks according to the present invention: when locating the fault point, a correlation between signal strength and acquisition location is established, and the range of the fault point is locked based on the correlation. For the identified fault location range, the signal strength data is further refined by increasing the acquisition density, thereby achieving precise calibration of the fault location.

[0015] The beneficial effects of this invention are as follows: This invention does not rely on complex and expensive equipment such as robot inspection and high-precision positioning, thereby reducing equipment dependence and maintenance costs, and solving the problems of strong equipment dependence, cumbersome maintenance and low reliability in harsh environments in the prior art. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments of the present invention will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention. Wherein: Fig. 1 The overall structure diagram is shown; Fig. 2 A connection diagram of the test component, receiver component, detector component, transmitter component, and grounding component is shown. Detailed Implementation

[0017] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0018] The terminology used in this invention is that which is currently widely used in the art in consideration of the function of the invention; however, these terms may vary according to the intent of those skilled in the art, precedent, or new technology in the art. Furthermore, specific terms may be chosen by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the invention. Therefore, the terms used in this specification should not be construed as simple names, but rather based on their meanings and the overall description of the invention.

[0019] Reference Figs. 1-2 This embodiment provides a device for fault location of 10kV overhead lines in distribution networks, including: Test component 1 is used to generate special frequency detection signals. Test component 1 can generate special frequency signals adapted to 10kV overhead line fault detection. The signal has the characteristics of resisting line noise interference, and the signal parameters can be dynamically adjusted according to the line length and fault type, providing a stable detection signal source for subsequent fault location and avoiding the problem of large location error due to signal instability or mismatch. It also includes a receiving component 2 for receiving information. The receiving component 2 can receive the line frequency signal strength data transmitted by the detection component 3 in real time, as well as fault characteristic information during the detection process, such as signal sudden changes and attenuation trends. It also has data caching and preliminary processing functions, and can perform format standardization processing on the received data to ensure that the data is accurately fed back to the system analysis stage, thus solving the problem of low positioning efficiency caused by asynchronous data transmission and inconsistent formats in the existing technology. It also includes a detection component 3 for detecting the intensity of special frequency signals on the line. The detection component 3 can move along the 10kV overhead line to be tested, collect the distribution of special frequency signal intensity along the line, and the detection process meets the requirements of non-contact, does not damage the line insulation, and can accurately capture subtle changes in signal intensity, such as the signal difference between normal and faulty sections. The collected data is transmitted to the receiving component 2 in real time to form a complete signal intensity location correlation data chain, which solves the problems of ambiguous fault point location and inability to accurately distinguish faulty sections from normal sections in the existing technology. It also includes a transmitting component 4 for injecting a special frequency detection signal into the line under test. The transmitting component 4 is connected to the test component 1 and can be connected to the line under test in a detachable manner to achieve stable injection of the special frequency detection signal. The injection process ensures signal transmission efficiency and avoids signal leakage or interference with the normal operation of the line, thus solving the problems of unstable signal injection and easy interference with the normal operation of the line in the prior art. The grounding component 5 is used to form a signal loop. The grounding component 5, together with the test component 1 and the ground, forms a complete signal loop, providing a return path for the propagation of the special frequency detection signal in the line, ensuring the integrity and detectability of the detection signal, and solving the problem that the detection signal cannot be effectively propagated due to the incomplete signal loop in the prior art. Test component 1 is connected to transmitting component 4. Transmitting component 4 is used to detachably connect to the line under test to achieve signal injection. Grounding component 5 works with test component 1 and the ground to construct a complete signal loop. Detection component 3 can move along the line under test to collect the intensity of the special frequency signal along the line. Receiving component 2 is communicatively connected to test component 1 and detection component 3 respectively. It is used to receive the signal data of detection component 3 and synchronize the working status information of test component 1. Through such component linkage, a complete process from special frequency signal generation, injection, loop construction to signal detection and data reception is realized. It can quickly and accurately locate the fault point of 10kV overhead line, solve the problems of insufficient accuracy, cumbersome operation and limited applicability of existing fault location technology, and improve the efficiency and convenience of distribution network fault handling.

[0020] As an optional embodiment, the detailed structure, function, and collaborative working logic of each component of the fault location device for 10kV overhead lines in distribution networks are described in detail to further adapt to the actual needs of field inspection scenarios for overhead lines: Test component 1 includes a host 11, a transmitting antenna 12 located on one side of the host 11, and a test line 13 located at one end of the host 11. The host 11 has a built-in special frequency signal generation module and control unit, which can generate a special frequency AC high voltage signal with a frequency range of 150Hz to 250Hz to match the fault detection frequency requirements in the technical briefing. The host 11 has an operation panel and display screen on its surface, which can display parameters such as signal output status and voltage level in real time, which is convenient for maintenance personnel to set on site. The transmitting antenna 12 is a 4G / LORA dual-mode communication antenna, and its communication frequency band is matched with the receiving antenna 22 of the receiving component 2 to ensure that the positioning data and working status information between the host 11 and the handheld device 21 are synchronized without delay, and stable communication can be maintained even in mountainous areas, forests and other areas with weak signals. Test line 13 is a copper core shielded cable with a double-layer metal shielding mesh on its outer layer, which can effectively isolate electromagnetic noise interference around the overhead line and prevent the special frequency detection signal from attenuating or distorting during transmission. At the same time, both ends of test line 13 are equipped with waterproof threaded connectors. One end is screwed to the signal output interface of the host 11, and the other end is fixed to the signal input end of the injection clamp 41 to prevent water from entering during field operations in rainy weather and causing short circuits in the signal.

[0021] It should be noted that the inner layer of the double-layer metal shielding mesh is aluminum foil shielding, and the outer layer is woven mesh shielding.

[0022] The receiving component 2 includes a handheld device 21 and a receiving antenna 22. The transmitting antenna 12 is matched with the receiving antenna 22. The handheld device 21 is a portable structure, weighing no more than 500g, which is convenient for maintenance personnel to hold and inspect with one hand. Its front is equipped with a high-definition LCD screen, which can display the strength value of the special frequency signal transmitted by the detection clip 31 and the collection location association information in real time. It can also use different colors, such as green to indicate a normal signal and red to indicate a sudden change in signal, to intuitively indicate the line status. The receiving antenna 22 is detachably mounted on the top of the handheld device 21. It is a LORA band antenna, just like the transmitting antenna 12, with a communication distance of over 500 meters, meeting the data transmission requirements during long-distance overhead line inspections. The receiving antenna 22 has a foldable design and can be stored on the side of the handheld device 21 when not in use, reducing the carrying volume.

[0023] The detection component 3 includes a detection clamp 31 for holding the line and a detection rod 32 connected to the detection clamp 31. The detection clamp 31 is used to capture special frequency signals on the line, and the detection rod 32 is used to support the detection clamp 31 and transmit detection signals. The detection clamp 31 is an openable clamp structure with an arc-shaped conductive contact on its inner side. When closed, it can fit tightly against the outer wall of the conductor and capture special frequency signals through electromagnetic induction without damaging the line insulation. The detection clamp 31 also has a built-in high-sensitivity current sensor that can identify weak signal strength changes, such as the signal difference between the normal section and the fault section. The detection pole 32 is made of epoxy resin insulation material and is telescopic in length to adapt to overhead lines of different heights, avoiding the need for maintenance personnel to climb the pole for work. The detection pole 32 has a signal transmission line inside, one end of which is soldered to the signal output end of the detection clip 31, and the other end is plugged into the signal input interface of the handheld device 21, so that the special frequency signal captured by the detection clip 31 can be transmitted to the handheld device 21 without loss.

[0024] The transmitting component 4 includes an injection clip 41 for clamping the line and an injection rod 42 connected to the injection clip 41. The injection clip 41 is connected to the test lead 13 and is used to inject the special frequency detection signal generated by the test component 1 into the line under test. The injection clip 41 is made of high-strength alloy material, and its jaws are provided with anti-slip teeth and conductive plates. It is not easy to fall off after clamping the wire, and the conductive plates can reduce the contact resistance and ensure that the special frequency detection signal is efficiently injected into the line. The injection rod 42 is also made of insulating material and its length is adapted to the detection rod 32. Its top is equipped with a rotary joint that connects to the injection clamp 41, which can adjust the snap-fit ​​angle of the injection clamp 41, making it convenient to install in complex locations such as wire crossings and near towers. The signal input end of the injection clamp 41 is connected to the test line 13 through a waterproof threaded connector to achieve stable transmission of special frequency signals from the host 11 to the line.

[0025] When the grounding component 5 is inserted into the ground, current is conducted into the ground, thereby constructing a return path for the special frequency detection signal. The grounding component 5 includes a metal grounding pin and a grounding wire. One end of the grounding pin is pointed, which can be quickly inserted into the soil in the field. The other end is connected to the grounding wire through a terminal block. The other end of the grounding wire is securely connected to the grounding interface of the host 11. Through the grounding component 5, a complete special frequency signal loop can be formed, ensuring that the special frequency signal can be effectively propagated along the line and avoiding detection failure due to an incomplete loop.

[0026] Test line 13 is a shielded cable used to connect the host 11 and the injection clamp 41 to ensure stable transmission of the special frequency detection signal. In addition to the double-layer shielding structure, the outer sheath of test line 13 is made of weather-resistant PVC material, which can withstand temperature changes from -30℃ to 60℃, adapting to harsh environments such as high temperature, low temperature, rain and snow in the field. Moreover, the cable tensile strength is not less than 100N, avoiding cable breakage caused by pulling during inspection, and further ensuring the continuity and stability of special frequency detection signal transmission.

[0027] This embodiment provides a method for fault location of 10kV overhead lines in distribution networks, including: To construct a transmission loop for the special frequency detection signal, the special frequency detection signal can propagate in the line under test. Before constructing the loop, safety confirmation and component inspection must be completed. The maintenance personnel first contact the substation to disconnect the power switch of the line under test, hang a warning sign, and use a voltage tester to verify that the line is de-energized phase by phase. Then, place the main unit 11 of the test component 1 next to tower No. 1, about 500 meters away from the substation outlet. The bottom of the main unit 11 is padded with an insulating rubber pad to prevent moisture and short circuit. At the same time, check that the grounding pin of grounding component 5 is not bent or corroded, the insulation sheath of grounding wire is not cracked, and the waterproof connectors at both ends of test wire 13 are not damaged. In specific operation, first insert the grounding pin at a 45° angle into the moist soil next to tower No. 1, with an insertion depth of not less than 300mm. Use a grounding resistance tester to measure the grounding resistance to be ≤8Ω. Then, connect one end of the grounding wire to the grounding pin through the terminal block, and tighten the other end to the grounding interface of the host 11. Next, use the injection rod 42 of the transmitting component 4 to lift the injection clamp 41 to the A phase conductor of the line, open the jaws to clamp the wire, and ensure that the conductive sheet inside the jaws is tightly attached. Finally, connect one end of the test line 13 to the signal output interface of the host 11, and fix the other end to the signal input end of the injection clamp 41. This process forms a complete circuit. Press the circuit test button on the host 11. If the display shows a qualified indication, it means that the circuit is qualified, which can avoid the subsequent signal from being unable to propagate due to a circuit break.

[0028] A preset special frequency detection signal is continuously injected into the line under test. The signal parameter settings need to be adapted to the line characteristics of the PT equipment. Select "Special Frequency AC High Voltage Mode" through the host 11 operation panel and set the signal frequency to 220Hz. This frequency is within the range of 150Hz to 250Hz to avoid the PT power frequency saturation area and prevent the PT core from overheating and being damaged. Adjust the output voltage to the medium range, corresponding to an output voltage of 7.5kV, which takes into account the signal propagation distance of 6km line and the safety of the equipment. At the same time, the anti-interference filtering function is enabled to filter out 50Hz power frequency noise around the line and avoid signal distortion.

[0029] Synchronous data communication is required during signal injection: Press the signal transmission button on the host 11, and the host display screen will show the signal output power and frequency deviation (≤±0.5Hz) in real time. The transmitting antenna 12 sends a normal signal injection command to the handheld device 21 of the receiving component 2. After the maintenance personnel hold the handheld device 21 and the receiving antenna 22 receives the command, the display screen will pop up a signal synchronization success prompt. If synchronization is not achieved, adjust the angle of the transmitting antenna 12 and the receiving antenna 22 to ensure stable signal transmission.

[0030] Special frequency signal strength information is collected at different locations along the line under test to form signal strength distribution data. The collection trajectory needs to be combined with the rural line layout plan: the line under test includes 3 branch points and 2 lightning arrester installation locations. The collection interval in key areas is set to 20 meters, and the collection interval in ordinary straight sections is set to 50 meters to ensure coverage of high-risk areas.

[0031] During data acquisition, the detection component 3 needs to be activated. The maintenance personnel extend the detection rod 32 of the detection component 3 to 3 meters, open the jaws of the detection clamp 31 and attach it to the A-phase conductor at the acquisition point. After 3 seconds of waiting for the signal to stabilize, the high-sensitivity current sensor built into the detection clamp 31 captures the special frequency signal and transmits it to the handheld device 21 through the signal line inside the detection rod 32. The handheld device 21 displays the signal strength value in real time on the display screen and records the coordinates of the acquisition point through the built-in GPS module, automatically generating a location signal strength correlation data table.

[0032] If an abnormality is encountered in the acquisition, such as the signal near surge arrester 1 fluctuating between 35-70μA, check whether the clamp of detection clip 31 is not tightly fitted due to wire oxidation or agricultural dust. After gently sanding the surface of the wire with fine sandpaper, re-clamp it and acquire data again until the signal is stable.

[0033] Based on the changing characteristics of signal strength distribution data, the location of the fault point of the line under test is located. In order to initially locate the fault section, it is necessary to analyze the signal change characteristics. The maintenance personnel retrieved the location signal strength data table through the handheld device 21 and found that the signal strength from the No. 1 branch point to the surge arrester 1 section (1~1.5km) was stable at 72-80μA. The signal strength from the surge arrester 1 to the No. 2 branch point (1.5~2km) dropped sharply from 70μA to 18μA, which was judged as a sudden change. The signal strength from the No. 2 branch point to the end section (2~6km) was consistently below 12μA, which was judged as an interruption. Based on this, the fault section was initially located between the No. 1 and No. 2 branch points (1.5~2km).

[0034] The precise fault location employs a binary search optimization method: For the 1.5–2 km fault range, signal strength is first collected at the midpoint of 1.75 km, reaching 42 μA, which is recorded as a transition segment characteristic; then, at 1.6 km, signal strength is collected at 65 μA, a characteristic close to the normal segment; at 1.65 km, signal strength is collected at 53 μA; at 1.68 km, signal strength drops sharply to 22 μA, determining the critical location of the signal change to be between 1.65 and 1.68 km. Subsequently, the collection interval is reduced to 1 meter, with signal strengths of 48 μA at 1.66 km, 32 μA at 1.67 km, and 19 μA at 1.675 km, ultimately determining the precise fault location to be at 1.67 km. Inspecting the line near this location reveals the fault, thus shortening fault location time, improving efficiency, and accurately identifying concealed surge arrester faults.

[0035] During the process of collecting special frequency signal strength information, the acquisition trajectory can be adjusted according to the line layout to ensure coverage of the key areas of the line under test; the change characteristics of signal strength distribution data include sudden changes, attenuation or interruption of signal strength, which can be used to distinguish normal line segments from faulty line segments.

[0036] When locating the fault point, a correlation is established between signal strength and acquisition location. Based on this correlation, the range of the fault point is locked. For the locked fault point range, the signal strength data is further refined by increasing the acquisition density to achieve accurate calibration of the fault point.

[0037] Finally, it should be noted that the methods and devices described in detail above are merely embodiments, and those skilled in the art can modify these embodiments in different ways as long as they do not depart from the scope of the present invention.

Claims

1. A device for fault location of 10 kV overhead line of distribution network 10, characterized in that: The utility model relates to a device for fault location of 10kV overhead line of distribution network, and the following steps: Construct the transmission loop of special frequency detection signal, make special frequency detection signal can spread in the line to be measured; Continuously inject the preset special frequency detection signal to the line to be measured; Collect the special frequency signal intensity information of different positions along the line to be measured to form signal intensity distribution data; Based on the change characteristics of signal intensity distribution data, locate the fault point position of the line to be measured. During the process of collecting the special frequency signal intensity information, the collection track can be adjusted according to the line layout to ensure that the key areas of the line to be measured are covered; The change characteristics of signal intensity distribution data include the mutation, attenuation or interruption of signal intensity, which can be used to distinguish normal line sections from fault line sections.

2. The apparatus for fault location of 10 kV overhead distribution lines according to claim 1, characterized in that: When locating the fault point position, an association between signal intensity and collection position is established, and the range of the fault point is locked based on the association.

3. The apparatus for fault location of 10 kV overhead distribution lines according to claim 2, characterized in that: ​ 4. The apparatus for fault location of 10 kV overhead distribution lines according to claim 3, characterized in that: ​ ​ 5. The apparatus for fault location of 10 kV overhead distribution lines according to claim 4, characterized in that: ​ ​ 6. The apparatus for fault location of 10 kV overhead distribution lines according to claim 5, characterized in that: ​ 7. The apparatus for fault location of 10 kV overhead distribution lines according to claim 6, characterized in that: ​ 8. A method for fault location of a distribution network 10 kV overhead line, characterized in that: ​ ​ ​ ​ ​ 9. The method for fault location of 10 kV overhead distribution lines according to claim 8, characterized in that: ​ ​ 10. The method for fault location of 10 kV overhead distribution lines according to claim 9, characterized in that: ​ The range of the failure point of the lock is further refined by the encrypted collection density to further refine the signal strength data, and the accurate calibration of the failure point is realized.

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