Underground cable high-resistance fault positioning system

Abstract

The invention discloses an underground cable high-resistance fault positioning system, which belongs to an underground cable monitoring device, and comprises a transmitter and a receiver, and more importantly, the system also comprises a high-resistance fault positioning acquisition sensor, the high-resistance fault positioning acquisition sensor is provided with an A end and a B end, the A end and the B end of the high-resistance fault positioning acquisition sensor are connected through a signal line, and the A end of the high-resistance fault positioning acquisition sensor is connected to the receiver; the receiver is used for comparing the first phase signal with the second phase signal, and determining a high-resistance fault point of the underground cable according to the change of the first phase signal and the second phase signal; according to the underground high-resistance cable fault positioning method, the high-resistance fault positioning acquisition sensor is additionally arranged, the phase signal from the transmitter is acquired by a human body, and the fault position of the underground high-resistance cable is positioned by using the phase difference algorithm, so that compared with traditional high-voltage flash, the cable can be prevented from being burnt out, and the fault positioning accuracy is relatively high.

Description

Technical Field

[0001] The present invention relates to an underground cable monitoring device, and more specifically, mainly to an underground cable high-resistance fault locating system. Background Art

[0002] Underground cable laying is gradually applied to various scenarios such as cities due to its concealment. However, since the cables are laid underground, once a fault occurs, it will bring difficulties to maintenance. Traditional fault location generally uses the acoustic magnetic synchronization method (pointing instrument) or the step voltage method (A bracket). The two are different instruments. Engineers need to carry different equipment to find faults according to different faults: high-resistance faults (above 1000Ω) use the acoustic magnetic synchronization method (pointing instrument). The transmitter applies a high-voltage flash signal (generally 8KV, 16KV, 32KV) to the faulty cable, generates a discharge signal at the fault point, and gradually burns down the impedance of the high-resistance fault. The point-finding instrument receives the discharge signal at the fault point; low-resistance faults (impedance below 1000Ω or lower) use the A bracket step voltage method to locate the fault. The transmitter sends a low-voltage pulse signal, and the receiver is connected to the A bracket to determine the fault point through the step voltage. In response to the above problems, especially high-resistance faults reaching several thousand ohms or megaohms, such as a 2MΩ grounding fault, communication optical cables, railway control cables, street light cables, etc. cannot be located by the high-voltage flash method. This is because when a high-voltage flash signal is added to these low-voltage cables, it will damage (burn) these cables or cause communication signals or railway control signals to malfunction. Therefore, it is necessary to further study and improve the high-resistance fault detection and positioning devices for underground cables. Summary of the invention

[0003] One of the purposes of the present invention is to provide an underground cable high-resistance fault location system in view of the above-mentioned shortcomings, in order to solve the technical problems that similar technologies in the prior art cannot locate faults of underground high-resistance cables and high-voltage flash methods are prone to burn cables.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions: The present invention provides an underground cable high-resistance fault locating system, comprising a transmitter and a receiver. More importantly, the system also comprises a high-resistance fault locating and collecting sensor, wherein the high-resistance fault locating and collecting sensor has an A end and a B end, wherein the A end and the B end of the high-resistance fault locating and collecting sensor are connected via a signal line, and the A end and the B end of the high-resistance fault locating and collecting sensor are respectively connected to the receiver; the transmitter is used to transmit a directional phase signal to the underground cable; the A end of the high-resistance fault locating and collecting sensor is used to collect the phase signal from the transmitter underground through the human body, and after processing the phase signal, transmit it to the receiver as a first phase signal; the B end of the high-resistance fault locating and collecting sensor is used to collect the phase signal from the transmitter underground through the human body, and after processing the phase signal, transmit it to the receiver as a second phase signal; the receiver is used to compare the first phase signal with the second phase signal, and determine the underground cable high-resistance fault point through the changes of the first phase signal and the second phase signal.

[0005] Preferably, a further technical solution is: the A end of the high-resistance fault location acquisition sensor has a first acquisition coil, the first acquisition coil is wound on a soft magnetic core, the first acquisition coil is also connected to a first PCB board, the first acquisition coil is used to collect phase signals and transmit them to the first PCB board, which is amplified and analog-to-digital converted by the first PCB board and then transmitted to the receiver as a first phase signal.

[0006] A further technical solution is: the B end of the high-resistance fault location acquisition sensor has a second acquisition coil, the second acquisition coil is wound on a magnetic rod, the second acquisition coil is also connected to a second PCB board, the second acquisition coil is used to collect phase signals and transmit them to the second PCB board, which is amplified and analog-to-digital converted by the second PCB board and then transmitted to the receiver as a second phase signal.

[0007] A further technical solution is: the second acquisition coil is connected to the spring at the bottom of the outer shell at the B end of the high-resistance fault location acquisition sensor, the outer shell is cylindrical, and the two ends of the spring are respectively in conflict with the second acquisition coil and the bottom of the outer shell.

[0008] A further technical solution is: the first acquisition coil is connected to the spring at the bottom of the watch case at the A end of the high-resistance fault location acquisition sensor, and the two ends of the watch case have bracelets, and the two ends of the spring are respectively in conflict with the first acquisition coil and the bottom of the watch case, and the first acquisition coil and the soft magnetic core are both placed inside the bracelet.

[0009] A further technical solution is: the receiver includes a control module, the control module is connected to a phase signal interface, and the control module is used to receive the first phase signal and the second phase signal through the phase signal interface; the control module is also respectively connected to a 3D magnetic rod antenna, a geo-positioning module, a Bluetooth module, a 4G / 5G module and an operation module; the 3D magnetic rod antenna is used to detect the position of underground pipelines in multiple dimensions; the geo-positioning module is used to collect the location information of the current underground cable high-resistance fault point, and transmit it to the cloud server through the 4G / 5G module; the Bluetooth module is used to link with other smart terminals; the operation module is used to operate the control module to control the operating status of the receiver.

[0010] A further technical solution is: the system also includes a cloud server, and the cloud server is used to draw an electronic map of the underground cables at the location of the current underground cable high-resistance fault point based on the location information.

[0011] Compared with the prior art, one of the beneficial effects of the present invention is: by adding a high-resistance fault locating and collecting sensor, the phase signal from the transmitter is collected by the human body, and then the fault position of the underground high-resistance cable is located using a phase difference algorithm. Compared with traditional high-voltage flashes, it can avoid burning the cable and has a higher accuracy in fault locating. At the same time, the underground cable high-resistance fault locating system provided by the present invention has a simple structure, can be modified based on existing transmitter and receiver devices, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A schematic diagram of a fault location principle for illustrating an embodiment of the present invention.

[0013] Figure 2 A usage state diagram for illustrating an embodiment of the present invention.

[0014] Figure 3 for Figure 2 Schematic diagram of the A-end structure of the medium and high resistance fault location acquisition sensor.

[0015] Figure 4 for Figure 2 Schematic diagram of the B-end structure of the medium and high resistance fault location acquisition sensor.

[0016] Figure 5 The figure is a schematic block diagram of a receiver structure for illustrating an embodiment of the present invention.

[0017] Figure 6 A circuit model diagram for illustrating an embodiment of the present invention.

[0018] In the figure, 1 is a transmitter, 2 is a receiver, 3 is an A-end of a high-resistance fault location acquisition sensor, 31 is a first acquisition coil, 32 is a soft magnetic core, 33 is a first PCB board, 34 is a watch case, 35 is a wristband, 4 is a B-end of a high-resistance fault location acquisition sensor, 41 is a second acquisition coil, 42 is a magnetic rod, 43 is a second PCB board, and 44 is an outer shell. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with the accompanying drawings.

[0020] refer to Figure 1 As shown, one embodiment of the present invention is an underground cable high-resistance fault location system, the system includes a transmitter, a receiver and a high-resistance fault location acquisition sensor; wherein the structure and function of the transmitter and the receiver are similar to most similar products on the market.

[0021] That is, when detecting the depth of the cable path, identifying the cable, and locating the fault, the transmitter sends multiple frequency signals, and the receiver receives the sent signals on the ground. That is, the transmitter sends signals of different frequencies on the cable, forming a signal loop with the earth through the cable core or armor, and the receiver receives the current magnetic field signal of the cable core or metal armor on the ground, thereby calculating the phase value to locate the fault point. At the same time, the cable path depth detection and identification functions are realized.

[0022] The active detection frequencies of the two are: 11Hz, 16Hz, 22Hz, 32Hz, 33Hz, 64Hz, 66Hz, 98Hz, 128Hz, 196Hz, 256Hz, 273Hz, 320Hz, 480Hz, 491Hz, 512Hz, 526Hz, 577Hz, 640Hz, 960Hz, 982Hz, 1024Hz, 1052 Hz, 1154Hz, 1280Hz, 2.56kHz, 3.20kHz, 4.09kHz, 5.12kHz, 6.4kHz, 8.192kHz, 8440Hz, 8928Hz, 9820Hz, 10kHz, 33kHz, 66kHz, 82kHz, 83.1kHz, 131kHz, 133kHz, 201kHz (11Hz, 16Hz, 22Hz, 32Hz , 33Hz, 64Hz, 66Hz, 98Hz, 128Hz, 196Hz, 256Hz, 273Hz, 320Hz, 480Hz, 491Hz, 512Hz, 526Hz, 577Hz, 640Hz, 960Hz, 982Hz, 1024Hz, 1052 Hz, 1154Hz, 1280Hz, 2.56kHz, 3.20kHz, 4.09kHz, 5.12kHz, 6.4kHz, these frequency signals are directional, the receiver can identify the signal direction, when locating the fault, the receiver on the ground can retrieve the phase signal of the transmitted signal in the cable transmission); and the power frequency passive detection frequency is: 50Hz, 60Hz.

[0023] The transmitter is designed to transmit signals in three power levels: low, medium and low. The low power is 15W, the medium power is 200W and the high power is 2000W. Low power transmission is used for fault location of communication optical cables, railway control cables and street light cables below 1000V. Medium power transmission is used for fault location of 10KV and 35KV power cables, and high power is used for fault location of high voltage cables of 110KV and above. At the same time, the transmitter integrates the DTR traveling wave fault ranging function, which can pre-position the fault distance of low-resistance fault cables. The transmitter transmits signals including direct connection method loading signals, that is, for cables disconnected by power outage, adding signals from the core wire; it can also be used for live cables, through armored signals. Coupling method loading signals, that is, for live cables or power-off cables, there is armored grounding at both ends of the cable to form a loop. Induction method loading signals, that is, directly inducing signals from the ground to the cable, and armored grounding at both ends of the cable forms a signal transmission loop, which is applicable to both live and power-off cables.

[0024] The receiver receives the transmission signal transmitted by the transmitter through the metal layer of the cable on the ground, so as to test the path direction, burial depth and fault location of the cable underground. The receiver is compatible with the functions of the pipeline instrument. The receiver integrates the RTK millimeter-level geolocation module to achieve accurate geographical location positioning of the cable underground, high-precision mapping and fault location.

[0025] The above-mentioned high-resistance fault location acquisition sensor adopts the phase difference measurement method, which can quickly locate high-resistance faults below 3MΩ. Traditional TDR rangefinders can only pre-locate faults below 1000Ω. Many faults require high-voltage flash method in combination with a fixed-point instrument to find the fault.

[0026] In this embodiment, the high-resistance fault location acquisition sensor used has an A end and a B end, and the A end and the B end of the high-resistance fault location acquisition sensor are connected through a signal line, and the A end and the B end of the high-resistance fault location acquisition sensor are also connected to the receiver 2 respectively.

[0027] The transmitter 1 is used to transmit a directional phase signal to an underground cable.

[0028] The A end of the high-resistance fault location acquisition sensor is used to collect the phase signal from the transmitter 1 underground through the human body, and after processing the phase signal, transmit it as the first phase signal to the receiver 2. Similarly, the B end of the high-resistance fault location acquisition sensor is used to collect the phase signal from the transmitter 1 underground through the human body, and after processing the phase signal, transmit it as the second phase signal to the receiver 2.

[0029] The receiver 2 is used to compare the first phase signal with the second phase signal, and determine the high-resistance fault point of the underground cable through the changes between the first phase signal and the second phase signal.

[0030] Specific, combined Figure 3 As shown, the A end of the above-mentioned high-resistance fault location acquisition sensor has a first acquisition coil 31, the first acquisition coil 31 is wound on a soft magnetic core 32, and the first acquisition coil 31 is also connected to a first PCB board 33. The first acquisition coil 31 is used to collect phase signals and transmit them to the first PCB board 33. The first PCB board 33 has a signal amplifier and an analog-to-digital converter, and then the first PCB board 33 can amplify and convert the analog-to-digital signal, and then transmit it to the receiver 2 as a first phase signal.

[0031] Furthermore, to facilitate wearing and use, the A end of the high-resistance fault location acquisition sensor can be designed in the form of a bracelet, so that the operator can wear the A end of the high-resistance fault location acquisition sensor on one hand and hold the receiver 2 in the other hand, that is, the above-mentioned first acquisition coil 31 is connected to the spring at the bottom of the surface shell 34 of the A end of the high-resistance fault location acquisition sensor, and the two ends of the surface shell 34 have a bracelet 35, and the two ends of the spring are respectively in conflict with the first acquisition coil 31 and the bottom of the surface shell 34, and the first acquisition coil 31 and the soft magnetic core 32 are both placed inside the bracelet 35.

[0032] Similarly, combined Figure 4 As shown, the B end of the above-mentioned high-resistance fault location acquisition sensor has a second acquisition coil 41, the second acquisition coil 41 is wound on the magnetic rod 42, and the second acquisition coil 41 is also connected to the second PCB board 43. The second acquisition coil 41 is used to collect the phase signal and transmit it to the second PCB board 43. The second PCB board 43 also has a corresponding signal amplifier and analog-to-digital converter, and then after amplification and analog-to-digital conversion by the second PCB board 43, it is transmitted to the receiver 2 as a second phase signal.

[0033] Furthermore, the B end of the high-resistance fault location acquisition sensor can be designed to be a cylindrical shape that is convenient for handholding, and then its outer shell 11 can be designed to be cylindrical, and then the second acquisition coil 41 inside it is connected to the spring at the bottom of the outer shell 44 of the B end of the high-resistance fault location acquisition sensor, and the two ends of the spring are respectively in conflict with the second acquisition coil 41 and the bottom of the outer shell 44.

[0034] The principle of high-resistance fault location is that there is a large distributed capacitance between the cable cores and between the cores and the earth's armored metal layer. The original fault detection methods are all affected by the distributed capacitance. This method uses the existence of distributed capacitance. Even if there is a high-resistance fault, the signal phase before and after the fault point will change significantly. Using this point, the phase difference of the signal before and after the fault point can be measured to locate the cable high-resistance grounding fault.

[0035] Specifically, if Figure 6As shown in the figure, the signal transmitter injects a low-frequency sinusoidal voltage signal between the fault core and the ground. Due to the existence of the ground fault resistance Rx and the distributed capacitance C to the ground, a closed loop is formed between the cable core and the ground. Under the action of the AC voltage signal, the loop generates an AC current I. The current amplitude in the fault line core is decreasing from point P to point D; since the distributed capacitance of the core to the ground in front of the ground fault point X is evenly distributed, the current amplitude from point P to point A is evenly reduced. After passing through the fault point X, in addition to reducing the leakage current caused by the distributed capacitance, the leakage current caused by the ground resistance is also reduced. Therefore, the current amplitude suddenly decreases after passing through the fault point. Current relationship: IP > IA > IB > ID. In front of the fault point X: the current phase of each measuring point PAB is ahead of the voltage phase of the ground fault point X, and this current leading voltage phase gradually decreases: φP>φA>φB; after passing through the ground fault point X, it suddenly becomes 90°, φd= 90°. Therefore, the high-resistance grounding fault can be located by testing the phase before and after the fault point.

[0036] As mentioned above, if Figure 1 and Figure 2 As shown, the above phase difference measurement algorithm is a high-resistance fault location sensor that requires two people to operate. One person holds the receiver and wears a bracelet-type (similar to the shape of a watch) phase acquisition sensor A, and the other person holds the phase acquisition sensor B. The distance between AB is kept 4-5 meters. The receiver collects the directional phase signal sent by the transmitter through the human body and the collector sensors at both ends of AB.

[0037] The A-end of the high-resistance fault location and collection sensor is designed as a bracelet-type collector, because the engineer at the A-end needs to hold a pipeline path meter (which indicates the path depth and location of underground cables during detection) and it is more convenient for the engineer at the A-end to wear the sensor in a watch-like manner, so a bracelet-watch-like structure is designed.

[0038] During the fault location process, the engineer at the A end of the high-resistance fault location acquisition sensor collects the phase signal from the ground to the transmitter through the human body, and transmits it to the stainless steel lower shell 5 of the bracelet through the arm. The coil introduction interface 6 is installed at the stainless steel lower shell. The collected phase signal is connected to the A end phase signal processing PCB board through the coil 2. After the phase signal is processed by the A end PCB circuit and chip, it is transmitted to the receiver through the phase signal output line 10 and then compared with the phase signal at the B end.

[0039] Similarly: the engineer at the B end of the high-resistance fault location acquisition sensor collects the phase signal from the ground to the transmitter through the human body, holding the B end phase acquisition sensor. The shell of the B end phase acquisition sensor is made of stainless steel. The phase signal collected by the human body is transmitted to the stainless steel shell by hand. The bottom of the stainless steel shell is connected to the internal spring, the spring is connected to the coil, the coil is wound on the magnetic rod, and then connected to the phase processing PCB board at the B end. After the phase signal is processed by the B end PCB circuit and chip, it is transmitted to the receiver through the phase signal output line 12, and then compared with the phase signal at the A end.

[0040] Due to the distributed capacitance and fault grounding resistance of the cable, the phases are opposite before and after the fault point. When the A-end acquisition sensor gradually approaches the fault point, the positive phase gradually increases; when the A-end acquisition sensor passes the fault point, the phase is immediately opposite, and a negative phase value appears. When the fault point is at the center of the AB sensors, the phase is 0°. Therefore, this sensor can quickly locate high-resistance faults, including low-resistance faults. The operation is simpler and faster, saving a lot of time and manpower.

[0041] The phase signals collected at both ends of the AB of the high-impedance fault location acquisition sensor are first amplified, detected, filtered, and then amplified in the second stage through their respective PCB circuits and processing chips, and converted into digital phase signals, which are transmitted to the receiver respectively. The receiver then compares and analyzes the two signals and gives the final phase difference value to locate the fault point.

[0042] refer to Figure 5 As shown, the above receiver (2) includes a control module, the control module is connected to the phase signal interface, and the control module is used to receive the first phase signal and the second phase signal through the phase signal interface; the control module is also connected to the 3D magnetic rod antenna, the geolocation module (such as GPS or Beidou satellite module), the Bluetooth module, the 4G / 5G module and the operation module (including physical buttons and touch screen); the 3D magnetic rod antenna is used to detect the location of the underground pipeline in multiple dimensions; the geolocation module is used to collect the location information of the current underground cable high-resistance fault point and transmit it to the cloud server through the 4G / 5G module; the Bluetooth module is used to link with other smart terminals; the operation module is used to operate the control module to control the operating state of the receiver 2. Further, the system in the above embodiment also includes a cloud server, and the cloud server is used to draw an electronic map of the underground cable at the location of the current underground cable high-resistance fault point according to the location information.

[0043] Furthermore, the APP program running on the smart terminal can realize electronic map drawing by the cloud server based on GNSS data. The test data can be presented completely and accurately on the map, and all cable information can be directly queried on the map. The text descriptions and photo information of all identification points can be directly clicked to view. The map data can be directly imported into CAD, and the full-factor cable path map and fault location map can be automatically generated, drawn, and output under the CAD software, realizing full-factor, standardized, and consistent drawing, storage, and digitization.

[0044] In addition to the above, it should be noted that "one embodiment", "another embodiment", "embodiment", etc. mentioned in this specification refer to the specific features, structures or characteristics described in conjunction with the embodiment included in at least one embodiment generally described in this application. The same expression appearing in multiple places in the specification does not necessarily refer to the same embodiment. Further, when describing a specific feature, structure or characteristic in conjunction with any embodiment, it is claimed that the realization of such feature, structure or characteristic in conjunction with other embodiments also falls within the scope of the present invention.

[0045] Although the present invention is described herein with reference to a number of illustrative embodiments of the present invention, it will be appreciated that those skilled in the art may devise many other modifications and implementations that fall within the scope and spirit of the principles disclosed herein. More specifically, within the scope of the present disclosure, drawings, and claims, a variety of variations and improvements may be made to the components and / or layout of the subject combination layout. In addition to variations and improvements made to the components and / or layout, other uses will also be apparent to those skilled in the art.

Claims

1. An underground cable high-resistance fault location system, comprising a transmitter and a receiver, characterized in that: It also includes a high-resistance fault location acquisition sensor, the high-resistance fault location acquisition sensor has an A end and a B end, the A end and the B end of the high-resistance fault location acquisition sensor are connected through a signal line, and the A end and the B end of the high-resistance fault location acquisition sensor are also connected to the receiver respectively; The transmitter is used to transmit a directional phase signal to the underground cable; The A end of the high-resistance fault location acquisition sensor is used to collect the phase signal from the transmitter underground through the human body, and after processing the phase signal, transmit it to the receiver as a first phase signal; The B end of the high-resistance fault location acquisition sensor is used to collect the phase signal from the transmitter underground through the human body, and after processing the phase signal, transmit it to the receiver as a second phase signal; The receiver is used to compare the first phase signal with the second phase signal, and determine the high-resistance fault point of the underground cable through the change between the first phase signal and the second phase signal.

2. The underground cable high-resistance fault location system according to claim 1, characterized in that: The A end of the high-resistance fault location acquisition sensor has a first acquisition coil, which is wound on a soft magnetic core. The first acquisition coil is also connected to a first PCB board. The first acquisition coil is used to acquire a phase signal and transmit it to the first PCB board. After amplification and analog-to-digital conversion by the first PCB board, the first phase signal is transmitted to the receiver.

3. The underground cable high-resistance fault location system according to claim 1 or 2, characterized in that: The B end of the high-resistance fault location acquisition sensor has a second acquisition coil, which is wound around a magnetic rod and is also connected to a second PCB board. The second acquisition coil is used to acquire a phase signal and transmit it to the second PCB board. After amplification and analog-to-digital conversion by the second PCB board, the signal is transmitted to the receiver as a second phase signal.

4. The underground cable high-resistance fault location system according to claim 3, characterized in that: The second acquisition coil is connected to a spring at the bottom of the outer shell at the B end of the high-resistance fault location acquisition sensor. The outer shell is cylindrical, and the two ends of the spring are respectively in conflict with the second acquisition coil and the bottom of the outer shell.

5. The underground cable high-resistance fault location system according to claim 2, characterized in that: The first acquisition coil is connected to the spring at the bottom of the watch case at the A end of the high-resistance fault location acquisition sensor. The two ends of the watch case are provided with a wristband. The two ends of the spring are respectively in conflict with the first acquisition coil and the bottom of the watch case. The first acquisition coil and the soft magnetic core are both placed inside the wristband.

6. The underground cable high-resistance fault location system according to claim 1, characterized in that: The receiver includes a control module, the control module is connected to a phase signal interface, and the control module is used to receive the first phase signal and the second phase signal through the phase signal interface; The control module is also connected to the 3D magnetic rod antenna, the geolocation module, the Bluetooth module, the 4G / 5G module and the operation module respectively; The 3D magnetic rod antenna is used to detect the location of underground pipelines in multiple dimensions; The geolocation module is used to collect the location information of the current underground cable high-resistance fault point and transmit it to the cloud server through the 4G / 5G module; The Bluetooth module is used to link with other smart terminals; The operation module is used to operate the control module to control the operating state of the receiver.

7. The underground cable high-resistance fault location system according to claim 6, characterized in that: The system also includes a cloud server, which is used to draw an electronic map of the underground cables at the location of the current high-resistance fault point of the underground cables based on the location information.

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