Single-core cable outer protective sleeve damage fault positioning construction method and system

Abstract

The invention discloses a single-core cable outer protective sleeve damage fault positioning construction method and system, and relates to the technical field of fault positioning, and the method comprises the specific steps: 1, verifying whether a cable outer protective sleeve is damaged or not based on an insulation test and DC withstand voltage test combination method, and if yes, executing the step 2; if not, judging that the cable is qualified; step 2, positioning a fault point of the cable by combining a pulse voltage method and an acoustic-magnetic synchronization method; 3, repairing the cable according to a positioning result; 4, carrying out the DC voltage withstand test on the repaired cable, verifying the repair qualification, and if the repair qualification is qualified, putting the cable into use; and if not, repeating the steps 1-4. According to the method, a combined positioning strategy of the pulse voltage method and the acoustic-magnetic synchronization method is adopted, the fault point searching time is shortened, and the positioning accuracy is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fault location, and more specifically, to a construction method and system for locating the breakage fault of the outer protective sleeve of a single-core cable. Background Art

[0002] At present, with the continuous expansion of the operating mileage of Chinese railways, as the core infrastructure to ensure the safe operation of trains, the 10kV power supply through line system of railways has comprehensively adopted a single-core cable structure to replace the traditional three-core cable, reducing the number of intermediate joints to reduce the failure rate and providing primary / comprehensive dual power supply guarantees for signal systems, communication base stations and equipment along the line.

[0003] However, there are significant technical bottlenecks in the laying construction process of 10kV single-core cables: limited by complex working conditions such as narrow space operation in tunnels, construction accuracy requirements for crossing and mechanical traction control, some cables have micron-level outer sheath breakages that are invisible to the naked eye during the construction stage. Such defects will generate a large grounding loop current after the cable is put into operation, resulting in an accelerated electrochemical corrosion rate of the sheath layer and ultimately causing cable failures, affecting power supply reliability.

[0004] Therefore, how to achieve the non-destructive laying of the outer sheath of a single-core cable in a complex construction environment and ensure the power supply reliability of high-speed railways is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a construction method and system for locating the breakage fault of the outer protective sleeve of a single-core cable, overcoming the above defects.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A construction method for locating the breakage fault of the outer protective sleeve of a single-core cable, the specific steps are as follows:

[0008] Step 1: Verify whether the outer sheath of the cable is damaged based on the combination method of insulation testing and DC withstand voltage test. If so, execute Step 2; if not, it is determined that the cable is qualified;

[0009] Step 2: Locate the fault point of the cable by combining the pulse voltage method and the acoustic-magnetic synchronous method;

[0010] Step 3: Repair the cable according to the positioning result;

[0011] Step 4: Perform the DC withstand voltage test on the repaired cable to verify the repair qualification. If it is qualified, it is put into use; if it is unqualified, repeat Steps 1 - 4.

[0012] Optionally, the breakage judgment step in Step 1 is:

[0013] Step 11: Collect the insulation resistance value of the cable outer sheath, and determine whether the insulation resistance value is zero. If so, it is determined that the cable is damaged; if not, proceed to Step 12;

[0014] Step 12: Apply a DC voltage with a fixed amplitude between the metal shielding layer of the cable and the ground. If it is not broken down within the preset time threshold, it is determined that the cable is qualified; if it is broken down within the preset time threshold, it is determined that the cable is damaged.

[0015] Optionally, for the cable determined to have a cable damage fault, use the method of controlling variables to repeat the insulation test and the DC withstand voltage test under different temperature and humidity conditions for re-inspection.

[0016] Optionally, the specific steps of the fault point location in Step 2 are as follows:

[0017] Apply a DC high voltage signal to the cable with a cable damage fault to break down and discharge the fault point, and calculate the fault distance using the pulse voltage method;

[0018] Based on the time difference between the propagation times of the pulse magnetic field signal and the sound signal generated by the discharge of the fault point, determine the position of the fault point by the acoustic-magnetic synchronization method.

[0019] Optionally, the calculation steps of the pulse voltage method are as follows:

[0020]

[0021] In the formula, v represents the pulse propagation speed; Δt represents the time difference between the fault point discharge pulse and the fault point reflection pulse.

[0022] Optionally, the specific steps of the acoustic-magnetic synchronization method are as follows:

[0023] Synchronously receive the pulse magnetic field signal and the sound signal generated by the discharge of the fault point, adjust the detection position until the time difference between the propagation times of the pulse magnetic field signal and the sound signal is minimized, and determine the position of the fault point.

[0024] A construction system for locating the damage fault of a single-core cable outer protective sleeve includes:

[0025] A fault cable judgment module, used to judge whether the cable outer sheath is damaged according to the combination method of insulation test and DC withstand voltage test;

[0026] A fault point location module, used to locate the fault point of the cable by combining the pulse voltage method and the acoustic-magnetic synchronization method;

[0027] A fault repair module, used to repair the cable according to the location result;

[0028] A repair verification module is used to perform the DC withstand voltage test on the repaired cable to verify the repair qualification.

[0029] Optionally, the faulty cable judgment module further includes a re-inspection unit, which is used to re-inspect the cable determined to have a cable breakage fault by repeating the insulation test and the DC withstand voltage test under different temperature and humidity conditions by using the control variable method.

[0030] As can be seen from the above technical solutions, the present invention provides a method and system for locating the fault of the outer protective sheath of a single-core cable. Compared with the prior art, it has the following beneficial effects:

[0031] Improved multi-level diagnostic accuracy: Through the synergistic effect of the insulation resistance test and the DC withstand voltage test, the detection accuracy of the outer sheath breakage is improved, effectively avoiding the missed judgment caused by the traditional single test.

[0032] Quick response and precise positioning: By adopting the combined positioning strategy of the pulse voltage method and the acoustic-magnetic synchronization method, the fault point search time is shortened and the positioning accuracy is improved.

[0033] Circulating current suppression and service life extension: Early breakage detection reduces the grounding circulating current value, delays the electrochemical corrosion rate of the sheath, and extends the service life of the cable. Description of the Drawings

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0035] Figure 1 It is a schematic flow chart of the method provided by the present invention;

[0036] Figure 2 It is a schematic diagram of the receiver receiving data provided by the present invention;

[0037] Figure 3 It is a schematic diagram of the waveform of the fault point in the pulse voltage method provided by the present invention;

[0038] Figure 4 It is a pulse diagram in the pulse voltage method provided by the present invention. Detailed Embodiments

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0040] One aspect of the embodiments of the present invention discloses a construction method for locating the damage of the outer protective sheath of a single-core cable. As Figure 1 shown, the specific steps are as follows:

[0041] Step 1: Verify whether the outer sheath of the cable is damaged based on the combination method of insulation test and DC withstand voltage test. If so, execute Step 2; if not, determine that the cable is qualified.

[0042] Step 2: Locate the fault point of the cable by combining the pulse voltage method and the acoustic-magnetic synchronization method.

[0043] Step 3: Repair the cable according to the positioning result.

[0044] Step 4: Perform a DC withstand voltage test on the repaired cable to verify the repair qualification. If it is qualified, put it into use; if it is unqualified, repeat Steps 1-4.

[0045] In one embodiment, the damage judgment step in Step 1 is as follows:

[0046] Step 11: Collect the insulation resistance value of the outer sheath of the cable and judge whether the insulation resistance value is zero. If so, judge that the cable is damaged; if not, execute Step 12.

[0047] Step 12: Apply a DC voltage with a fixed amplitude between the metal shielding layer of the cable and the ground. If it is not broken down within the preset time threshold, it is determined that the cable is qualified; if it is broken down within the preset time threshold, it is determined that the cable is damaged.

[0048] Further, with the help of an insulation resistance tester, the insulation resistance value of the outer sheath of a 10 kV single-core cable is tested, which is reflected by testing the insulation resistance between the cable steel armor and the ground. If the insulation resistance value is 0, then the outer sheath of this cable is surely damaged, and it is directly determined as a faulty cable, and the damaged position needs to be found and repaired in time. If the value measured by the insulation resistance tester is greater than 0, based on the electrical test standard, a DC withstand voltage test should be carried out on the outer sheath of the AC single-core cable; it is judged according to the relevant requirements that a DC voltage of 10 kV should be applied between each section of the cable metal shield or metal sleeve and the ground, and the pressurization time should be 1 min without breakdown. Combining the relationship between the phase voltage and the line voltage, applying a voltage value greater than 5.7 kV to a single cable for one minute is qualified, otherwise it does not meet the requirements and is determined as a faulty cable, and the fault needs to be processed as soon as possible.

[0049] In one embodiment, for the cable determined to have a cable breakage fault, the insulation test and the DC withstand voltage test are repeated under different temperature and humidity conditions by using the control variable method for re-inspection.

[0050] Further, by using the control variable method, a DC voltage value is applied between the metal sleeve of the unqualified cable and the ground at different temperatures and humidities to see if it meets the requirements.

[0051] In one embodiment, the specific steps of the fault point location in step 2 are as follows:

[0052] Step 21: Apply a DC high-voltage signal to the cable with a cable breakage fault to break down and discharge the fault point, and calculate the fault distance by using the pulse voltage method;

[0053] Step 22: Based on the propagation time difference between the pulse magnetic field signal and the sound signal generated by the discharge of the fault point, determine the fault point position by the acoustic-magnetic synchronization method.

[0054] In one embodiment, the specific steps of the acoustic-magnetic synchronization method are as follows:

[0055] Synchronously receive the pulse magnetic field signal and the sound signal generated by the discharge of the fault point, adjust the detection position until the propagation time difference between the pulse magnetic field signal and the sound signal is the smallest, and determine the fault point position.

[0056] Further, for unqualified cables, the pulse voltage method and the acoustic-magnetic synchronization method are combined to measure and locate the fault point.

[0057] In the faulty line, first, the transmitter in the fault detection device applies a voltage to the line to reproduce the fault. The current is sent out by the transmitter, flows through the faulty line, enters the ground at the grounding point and returns to the transmitter through the ground. This mode is applicable to faults such as low resistance, high resistance, phase-to-phase short circuit, and arc discharge.

[0058] The receiver in the fault detection device on the ground receives the wireless signal sent by the hanging sensor and visually displays the measurement result on the liquid crystal screen. Before the fault point, the current waveform persists, and after the fault point, the current waveform disappears. Coarse segmentation can be carried out first, and then precise positioning can be carried out to quickly determine the fault location. At the same time, at the fault point, the receiver will emit a sound to help quickly determine the fault location. The received signal is as Figure 2 shown.

[0059] Among them, the pulse voltage method is to apply a DC high-voltage signal to the faulty cable through a high-voltage signal generator to break down and discharge the fault point. After breakdown, a voltage traveling wave signal will be generated at the fault point. This signal propagates back and forth between the measurement end and the fault point. The fault distance is calculated by multiplying the time for the voltage traveling wave signal to travel back and forth once received and measured at the high-voltage end of the DC high-voltage generator by the propagation speed of the pulse signal. This method can detect both high- and low-resistance faults. The waveform at the fault point is as Figure 3 shown.

[0060] As Figure 4 shown, the fault point distance calculated by the pulse voltage method is:

[0061]

[0062] In the formula, v represents the pulse propagation speed; Δt represents the time difference between the discharge pulse at the fault point and the reflected pulse at the fault point.

[0063] The acoustic-magnetic synchronization method discharges the fault point through a high-voltage pulse. The high-voltage pulse signal will generate a pulse magnetic field signal and a sound signal around the cable, but their propagation speeds are different, resulting in a time difference. The location where this time difference is the smallest is the location of the fault point. This construction method uses the XHKJ-2000 overhead line fault location system and combines the pulse voltage method with the acoustic-magnetic synchronization method to measure and locate the fault point.

[0064] In one embodiment, step 3 is specifically as follows: Grind and clean the cable fault point, wrap it with insulating self-adhesive tape and connect it to the outer sheath to enhance and ensure the reliability of insulation; Half-lap and wind a waterproof tape with good quality on the insulating tape layer, half-lap and wind a PVC tape on the waterproof tape layer, and then encapsulate the fault point with armor tape to keep the cable fault point with a certain mechanical strength and ensure waterproof and corrosion resistance from the outside;

[0065] In one embodiment, step 4 is specifically as follows: conduct an electrical test on the repaired cable to meet the requirement for the DC withstand voltage test of the outer sheath of the AC single-core cable. More specifically: for the DC withstand voltage test of the insulation of the cross-bonding system to the ground, it is stipulated that a DC voltage of 10 kV should be applied between the metal shield or metal sheath of each section of the cable and the ground, the pressurization time should be 1 min, and there should be no breakdown; conduct an acceptance inspection on the cable laying, and power transmission can be carried out only after the electrical test is qualified.

[0066] On the other hand, this embodiment also discloses a construction system for locating the fault of the damaged outer protective sheath of a single-core cable, including:

[0067] A faulty cable judgment module, which is used to judge whether the outer sheath of the cable is damaged according to the combination method of insulation test and DC withstand voltage test;

[0068] A fault point location module, which is used to locate the fault point of the cable by combining the pulse voltage method and the acoustic-magnetic synchronization method;

[0069] A fault repair module, which is used to repair the cable according to the location result;

[0070] A repair verification module, which is used to conduct a DC withstand voltage test on the repaired cable to verify the repair qualification.

[0071] In one embodiment, the faulty cable judgment module further includes a re-inspection unit, which is used to re-inspect the cable determined to have a cable damage fault by repeating the insulation test and DC withstand voltage test under different temperature and humidity conditions by using the control variable method.

[0072] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0073] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A construction method for fault location of the damage of the outer protective sheath of a single-core cable, characterized in that, The specific steps are as follows: Step 1: Verify whether the outer sheath of the cable is damaged based on the combined method of insulation test and DC withstand voltage test. If so, proceed to Step 2; if not, determine that the cable is qualified. Step 2: Locate the fault point of the cable by combining the pulse voltage method and the acoustic-magnetic synchronous method. Step 3: Repair the cable according to the positioning result. Step 4: Conduct the DC withstand voltage test on the repaired cable to verify the repair qualification. If qualified, put it into use. If unqualified, repeat Steps 1 - 4.

2. The construction method for locating the damage fault of the outer protective sleeve of a single-core cable according to claim 1, wherein, The damage judgment steps in Step 1 are as follows: Step 11: Collect the insulation resistance value of the outer sheath of the cable and determine whether the insulation resistance value is zero. If so, determine that the cable is damaged; if not, proceed to Step 12. Step 12: Apply a DC voltage with a fixed amplitude between the metal shielding layer of the cable and the ground. If it is not broken down within the preset time threshold, determine that the cable is qualified. If it is broken down within the preset time threshold, determine that the cable is damaged.

3. A construction method for locating the damage fault of the outer protective sheath of a single-core cable according to claim 2, characterized in that, For the cable determined to have a cable damage fault, use the control variable method to repeat the insulation test and the DC withstand voltage test under different temperature and humidity conditions for re-inspection.

4. A construction method for locating the damage fault of the outer protective sheath of a single-core cable according to claim 1, characterized in that, The specific steps of the fault point location in Step 2 are as follows: Apply a DC high-voltage signal to the cable with a cable damage fault to break down and discharge the fault point, and calculate the fault distance using the pulse voltage method. Based on the time difference in the propagation of the pulse magnetic field signal and the sound signal generated by the discharge of the fault point, determine the location of the fault point by the acoustic-magnetic synchronous method.

5. A construction method for locating the damage fault of the outer protective sheath of a single-core cable according to claim 4, characterized in that, The calculation steps of the pulse voltage method are as follows: In the formula, v represents the pulse propagation speed; Δt represents the time difference between the fault point discharge pulse and the fault point reflection pulse.

6. The construction method for locating the damage fault of the outer protective sleeve of a single-core cable according to claim 4, characterized in that, The specific steps of the acoustic-magnetic synchronous method are as follows: Synchronously receive the pulse magnetic field signal and the sound signal generated by the discharge of the fault point, and adjust the detection position until the time difference in the propagation of the pulse magnetic field signal and the sound signal is minimized to determine the location of the fault point.

7. A construction system for locating the damage fault of the outer protective sleeve of a single-core cable, characterized in that, It includes: A faulty cable judgment module for judging whether the outer sheath of the cable is damaged based on the combined method of insulation test and DC withstand voltage test. A fault point location module for locating the fault point of the cable by combining the pulse voltage method and the acoustic-magnetic synchronous method. A fault repair module for repairing the cable according to the positioning result. A repair verification module for conducting the DC withstand voltage test on the repaired cable to verify the repair qualification.

8. A single-core cable outer sheath breakage fault location construction system according to claim 7, characterized in that, The faulty cable judgment module further includes a re-inspection unit for re-inspecting the cable determined to have a cable damage fault by using the control variable method to repeat the insulation test and the DC withstand voltage test under different temperature and humidity conditions.

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