A method and device for monitoring cable aging

Abstract

The present invention provides a method for monitoring cable aging treatment. The cable to be tested is assembled with a standard cable of a fixed length to form a tested cable, wherein the standard cable has a stable dielectric constant; a signal source is outputted by a DDS signal generator and then passes through the tested cable after passing through a power amplifier; a calculated length L1 of the tested cable is obtained by a frequency domain analysis method of an impedance spectrum or a phase spectrum or a time domain reflection method containing power energy; and the calculated length L1 of the tested cable is compared with an actual length L0 of the tested cable. The method can not only evaluate the aging condition of the tested cable but also monitor the aging repair process by using the standard cable and the cable length calculation, and is a very reliable and economical means.

Description

Technical Field

[0001] The invention belongs to the technical field of electric power equipment and relates to a method and a device for monitoring cable aging. Background Art

[0002] Insulated power equipment, especially insulated cables, are widely used in distribution networks. Any carelessness during the construction of cables can cause scratches or cracks on the insulation layer, causing the insulated cables to be damp. In the use of insulated cables, dampness also occurs from time to time. At the same time, cables are operated under high load conditions for a long time, causing the cables to age prematurely. Once moisture or water enters the cable, it will penetrate longitudinally from the gaps between the copper tape shielding outside the cable insulation and the gaps between the conductors. In severe cases, the test results will not meet the standards and power cannot be delivered as scheduled. In mild cases, water vapor will produce "water tree branches" in the cable under the action of a strong electric field, thereby reducing the insulation performance of the cable, and may even cause cable insulation breakdown within 5 to 10 years. Therefore, if the damp cable is not treated or treated incompletely, it will leave hidden dangers for the power supply system and may cause accidents during operation, resulting in economic losses or even life-threatening.

[0003] In order to solve the "water tree" phenomenon and aging defects of cables, repair fluid is usually used to treat and repair water tree aging of cross-linked vinyl cables. Its application has greatly improved the reliability of high-voltage power cables and has obvious economic benefits, but it has the following defects:

[0004] 1) It is mainly aimed at cables with serious overall aging. In the case of local aging, it is impossible to determine whether there is local aging or the location of local aging, which leads to blind aging repair and consumption of a large amount of repair fluid.

[0005] 2) The nano-filling method slowly penetrates into the cable insulation layer under pressure. If the cable is 1 km long, the penetration time may be as long as 8 to 12 hours. Even for cables with intermediate joints, the nano-liquid cannot pass through, resulting in repair failure.

[0006] 3) The current aging repair cannot track the repair status in real time during the repair process, and can only compare the dielectric loss or leakage current before and after the repair. Since the comparison data is only for the overall insulation parameters of the cable, there is no technical means to obtain the effect of local repair, such as the repair status of a certain area. Summary of the invention

[0007] In order to solve the problems raised in the above background technology. The present invention provides a method for monitoring cable aging management, which monitors the repair status from multiple links such as testing, repair, and tracking repair, and can timely know the local and overall repair status of the cable. When it is known that the severely aged area has been repaired, the repair can be stopped or the repair time can be reduced to improve the repair efficiency and save the repair fluid.

[0008] The specific technical solution for achieving the purpose of the present invention is:

[0009] An object of the present invention is to provide a method for monitoring cable aging management, the method comprising aging assessment, capable of assessing the aging condition of the cable, comprising the following steps:

[0010] S1: Assemble the cable to be tested with a standard cable of fixed length to form a tested cable, wherein the standard cable has a stable dielectric constant and length;

[0011] S2: The output signal source of the DDS signal generator passes through the power amplifier and then through the tested cable;

[0012] S3: The calculated length L1 of the tested cable is obtained by frequency domain analysis of impedance spectrum or phase spectrum;

[0013] S4: Determine whether the cable is aged or the degree of cable aging by comparing the calculated length L1 of the test cable with the actual length L0 of the test cable: when L1=L0, the aging management cable has not shown any aging phenomenon; when L1<L0, the aging management cable has shown any aging phenomenon; the smaller L1 is, the more serious the aging phenomenon is.

[0014] Furthermore, during the cable repair process, the S3 step can be started regularly or monitored in real time to obtain the calculated length L1 of the test cable. The change of L1 can determine the degree of repair of the aging management cable. The closer the value of L1 is to L0, the closer the repair is to completion.

[0015] Furthermore, the present invention also provides a cable aging treatment method comprising the following steps:

[0016] A1: Aging assessment, judging whether the aging management cable needs to be repaired through aging assessment of the cable aging management monitoring method;

[0017] A2: Aging location: by using the cable aging management monitoring method, move the test position of the aging management cable to find the area with the larger change value of L1, which is the aging area;

[0018] A3: Monitoring and repair: drilling holes or adding terminals at the front and rear ends of the aging area until they touch the metal layer or the armor layer, injecting repair liquid to eliminate moisture and fill the deterioration gaps. The repair process can be started regularly or the repair degree can be monitored in real time through the cable aging management monitoring method until the repair is completed;

[0019] A4: Insulation seal.

[0020] The cable aging management and monitoring method can be applied to various steps of cable aging management, such as aging assessment, aging location, and monitoring and repair.

[0021] Furthermore, in the step A3, before the repair liquid is injected, input gas is filled for a certain period of time, and the input gas includes one or more of pure air, helium, SF6 gas, argon, and hydrophilic chemical gas.

[0022] Furthermore, the repair liquid is one or more of insulating oil, silicone, silicone rubber liquid, phenylmethyldialkoxysilane (PhMeSi(OR)2), phenylmethyldimethoxysilane (PhMeSi(OMe)2), hydrophobic silica liquid, and superhydrophobic silica liquid.

[0023] Furthermore, in the A3: monitoring and repair step, current is passed through the cable core to generate heat and electric field to heat the insulation layer.

[0024] Another object of the present invention is to provide a cable aging management monitoring device, which includes: a central controller, a monitoring unit, and a test cable; the monitoring unit includes a signal acquisition system, a DDS signal generator, and a power amplifier; the central controller is connected to the signal acquisition system and the DDS signal generator respectively; the DDS signal generator is connected to the power amplifier, and the test cable is connected to the signal acquisition system and the power amplifier respectively.

[0025] The present invention also provides a cable aging treatment device, the device comprising:

[0026] Central controller, tested cables;

[0027] A monitoring unit, including a signal acquisition system and a DDS signal generator and a power amplifier connected in sequence;

[0028] High frequency heating element;

[0029] Inflating unit: includes a relay and a compressor connected in sequence;

[0030] Repair liquid injection unit: including a repair liquid injection pump, an injection valve, a flow monitor, and a multi-phase synchronous valve connected in sequence;

[0031] The central controller is connected to the monitoring unit and the inflation unit respectively; the tested cable is connected to the monitoring unit, the high-frequency heating element and the repair liquid injection unit respectively;

[0032] The power amplifier is connected to the high-frequency heating element.

[0033] Furthermore, the inflation unit is a gas inflation tank.

[0034] The relay is connected to the central controller, the compressor is connected to the repair liquid injection pump, and the multi-phase synchronous valve is connected to the tested cable.

[0035] Furthermore, the repair liquid injection system includes multiple repair liquid injection pumps.

[0036] Furthermore, the device also includes a negative pressure unit.

[0037] Furthermore, the negative pressure unit also includes a recovery system.

[0038] Furthermore, the repair liquid injection unit also includes one or more of an air pressure sensor, a flow rate sensor, a gas sensor, and an acoustic sensor.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. The present invention provides a method for monitoring cable aging. The method uses standard cables and cable length calculations to not only evaluate the aging of the cable to be tested and locate the aging area, but also monitor the aging repair process. It is a very reliable and economical means.

[0041] 2. The method of the present invention can timely know the local and overall repair status of the cable. When it is known that the severely aged area has been repaired, the repair can be stopped or the repair time can be reduced to improve the repair efficiency and save the repair fluid;

[0042] 3. The method of the present invention can heat the capacitive insulation layer of the tested cable while monitoring, so that the electric field of the capacitive insulation layer is uniform and a certain temperature is maintained, so that the repair precision of the nano repair liquid is improved, and the flow rate in the cable is increased, thereby improving the repair efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0044] Figure 1It is a structural schematic diagram of a cable aging management monitoring device of the present invention;

[0045] Figure 2 It is a structural schematic diagram of a cable aging treatment device of the present invention.

[0046] Figure 3 The structure diagram of the tested cable of the present invention is DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] Example 1

[0049] Combination Figure 1 , a cable aging management monitoring device, the device comprising:

[0050] Central controller;

[0051] Monitoring unit;

[0052] Cable under test;

[0053] The monitoring unit includes a signal acquisition system, a DDS signal generator, and a power amplifier;

[0054] The central controller is connected to the signal acquisition system and the DDS signal generator respectively; the DDS signal generator is connected to the power amplifier, and the tested cable is connected to the signal acquisition system and the power amplifier respectively.

[0055] The tested cable is assembled by the tested cable and a standard cable of fixed length. The standard cable, as a part of the tested cable, is calibrated in advance and can be considered as a stable constant, that is, has a stable dielectric constant and length;

[0056] Specifically, the cable to be tested is connected in series with the standard cable, such as Figure 3 shown.

[0057] It should be noted that there are two series connection sequences for the tested cables: standard cable + tested cable or tested cable + standard cable. More preferably, the standard cable is connected first, and then the tested cable. This series connection mode is more convenient in terms of calculation.

[0058] Specifically, the standard cable length is 0.1 meters to 300 meters, and more preferably, the standard cable length is 100 meters.

[0059] The output signal source of the DDS signal generator passes through the power amplifier and then the tested cable. The signal is collected by the signal acquisition system and the calculated length L1 of the tested cable is obtained by the frequency domain analysis method of impedance spectrum or phase spectrum or the time domain reflection method containing power energy.

[0060] Since the DDS output passes through the power amplifier, its test impedance spectrum or phase spectrum outputs a continuous frequency sweep signal, and it has the function of collecting the output voltage and feedback current when testing the impedance. Of course, DDS can also output a single frequency signal and collect its reflected voltage or current signal. Therefore, it is a TDR time domain reflection signal analysis method with power. Compared with the traditional TDR pulse voltage reflection method without power, the reflected voltage waveform may be attenuated and deformed, or there may be a problem of severe signal gain attenuation. The solution of this project can better make up for this defect. In practical applications, since the DDS output voltage has the ability to carry loads, the reflected voltage and feedback current can be analyzed separately, or the power of the reflected voltage and feedback current can be calculated to obtain the reflected power to analyze the time difference between the incident power and the reflected power to calculate the cable length L1;

[0061] It should be noted that the power amplifier output and the supporting acquisition system can be single-channel, that is, single-core cable monitoring, or multi-channel, which can realize the monitoring of three-phase or multi-phase cables.

[0062] By comparing the calculated length L1 of the test cable with the actual length L0 of the test cable, it is determined whether the cable is aged or the degree of cable aging: when L1=L0, the aging management cable has not shown any aging phenomenon; when L1<L0, the aging management cable has shown aging phenomenon; the smaller L1 is, the more serious the aging phenomenon is.

[0063] Furthermore, by collecting signals at different positions of the test cable, the calculated L1 value is compared with L0, and the point where L1 suddenly changes can obtain a more accurate aging area of ​​the cable under test, which is of great significance for cable repair.

[0064] Example 2

[0065] Combination Figure 2 , a cable aging treatment device, the device comprising:

[0066] Central controller, tested cables;

[0067] A monitoring unit, including a signal acquisition system, a DDS signal generator, and a power amplifier connected in sequence;

[0068] High frequency heating element;

[0069] Inflating unit: includes a relay and a compressor connected in sequence;

[0070] Repair liquid injection unit: including a repair liquid injection pump, an injection valve, a flow monitor, and a multi-phase synchronous valve connected in sequence;

[0071] The central controller is connected to the monitoring unit and the inflation unit respectively; the tested cable is connected to the monitoring unit, the high-frequency heating element and the repair liquid injection unit respectively;

[0072] The power amplifier is connected to the high-frequency heating element.

[0073] It should be noted that a solution is provided for the problem that the repair liquid penetrates slowly and takes a long time during the long-distance cable repair process. The power amplifier is connected to the high-frequency heating element, and can heat the capacitive insulation layer of the tested cable, so that the electric field of the capacitive insulation layer is uniform and maintains a certain temperature, and a high-frequency current signal is applied to the capacitive insulation layer of the cable, so that under the high-frequency electric field, the capacitive insulation layer is heated evenly, and the activity of the internal water molecules is increased, which is beneficial to the chemical neutralization of the repair liquid and micro-water, so that the repair precision of the repair liquid is improved, and the flow rate in the cable is increased, thereby improving the repair efficiency.

[0074] Specifically, the standard cable in the tested cable is first, and the cable to be tested is connected in series later, and the multi-phase synchronous valve is connected to the punched part on the cable to be tested to inject the repair liquid.

[0075] Specifically, the inflation unit further includes a set of gas filtering devices, so that the gas is filtered for humidity and impurities before being injected into the cable.

[0076] It should be noted that the inflation unit can be replaced by a gas inflation tank; the inflation system can also be a gas inflation tank or the like that can provide pressurized gas to the system, and the gas includes inert gas, insulating gas, such as pure air, helium, SF6 gas, argon, and one or more hydrophilic chemical gases.

[0077] Specifically, the repair liquid injection system has multiple repair liquid injection pumps that can inject different types of repair liquids. The repair liquid is injected into the cable through the repair liquid injection pump, injection valve, flow monitor and multi-phase synchronous valve, and fills the cable.

[0078] It should be noted that the repair liquid is one or more of insulating oil, silicone, phenylmethyldialkoxysilane (PhMeSi(OR)2), phenylmethyldimethoxysilane (PhMeSi(OMe)2), titanium dioxide, silicone rubber liquid, siloxane, hydrophobic silica liquid, and superhydrophobic silica liquid. For the insulation structure of low-voltage cables, the insulation performance can be improved by injecting insulating oil, or by injecting silicone nanomaterials or other liquids that can improve the insulation performance. However, the repair of silicone nanomaterials is not ideal in terms of cost or effect. The use of insulating oil has obvious advantages: the rated voltage of low-voltage cables is low, and the filling insulating oil changes its insulation layer material, which can better repair the damage or aging between multiple strands of wire cores; the filling insulating oil can use recycled oil with relatively low insulation strength, such as from waste transformers and capacitors above 10kV, which not only improves the value of resource recycling, but also reduces the purchase cost of filling oil. Especially for power grid companies or power supply departments, there are a large number of low-voltage secondary control cables and a large number of scrapped and replaced transformers and capacitors in the substation. After effectively combining the two, the insulation capacity of the low-voltage control cable is improved, the operation and maintenance cost is reduced, and the service life of the secondary control cable can be increased to a certain extent. Its economic value is very obvious.

[0079] Specifically, the device further comprises a negative pressure unit. The negative pressure unit is a vacuum device which can start the vacuuming work when the inflation system is inflated, and can also increase the flow rate of the repair liquid during the inflation process and the repair liquid injection process.

[0080] Specifically, the negative pressure unit also includes a recovery system. It can realize the gas and repair liquid recovery function. Even if there is residual gas, such as a trace of sulfur hexafluoride gas, it has good insulation performance and can improve the reliability of the cable. At the same time, by recovering the repair liquid, the repair cost is reduced.

[0081] Specifically, the repair liquid injection unit also includes one or more of an air pressure sensor, a flow rate sensor, a gas sensor, and an acoustic sensor.

[0082] It should be noted that the air pressure sensor can detect air pressure, flow and vibration signals, and can have a timed low air pressure alarm function, that is, when the received air pressure is lower than the set value after a certain period of time, it provides an audible and visual alarm function; the gas sensor and acoustic sensor detect the local area of ​​the laid and installed cables by patrolling, and detect and alarm the gas leaking through the gaps and holes, so as to locate the leakage point. Specifically, the monitoring and acquisition system also includes a communication module to manage the monitoring data in a wired or wireless mode. The monitoring and acquisition system can also test the impedance spectrum of the cable, including the impedance modulus spectrum and the impedance angle spectrum, and calculate the local aging gain, regularly compare the changes in the local aging gain, and compare the changes in the overall impedance spectrum or phase spectrum, to track the overall aging and local aging during the repair process.

[0083] Specifically, the monitoring unit also includes a coupling injection sensor and a feedback current sensor, which can realize online live monitoring and repair.

[0084] In a cable aging treatment device, during the aging repair process of a cable under test, water inside the cable under test is pre-treated and removed through an inflation system to ensure that the repair liquid can effectively fill the aging area. During the repair process, the S3 step can be started regularly or monitored in real time to obtain the calculated length L1 of the cable under test. The change of L1 can determine the repair degree of the aging treatment cable. The closer the value of L1 is to L0, the closer the repair is to completion. During the monitoring process, a high-frequency heating element heats the capacitive insulation layer of the cable under test. The capacitive insulation layer is heated evenly, and the activity of the internal water molecules is increased, which is beneficial to the chemical neutralization of the repair liquid and micro-water, so that the repair precision of the repair liquid is improved, and the flow rate in the cable is increased, thereby improving the repair efficiency.

[0085] Example 3

[0086] A method for monitoring cable aging management, the method includes aging assessment, which can assess the aging condition of the cable, and includes the following steps:

[0087] S1: Assemble the cable to be tested with a standard cable of fixed length to form a tested cable, wherein the standard cable has a stable dielectric constant and length;

[0088] S2: The output signal source of the DDS signal generator passes through the power amplifier and then through the tested cable;

[0089] S3: The calculated length L1 of the tested cable is obtained by frequency domain analysis of impedance spectrum or phase spectrum;

[0090] S4: Determine whether the cable is aged or the degree of cable aging by comparing the calculated length L1 of the test cable with the actual length L0 of the test cable: when L1=L0, the aging management cable has not shown any aging phenomenon; when L1<L0, the aging management cable has shown any aging phenomenon; the smaller L1 is, the more serious the aging phenomenon is.

[0091] The cable to be tested is a 10kV cross-linked polyethylene cable. If the length is 400 meters, the cable to be tested is 400 meters and the standard cable is 100 meters. The actual total length of the tested cable is 500 meters (L0). The calculated length L1 of the tested cable is obtained by the following method:

[0092] The starting point of the DDS signal generator's transmission frequency is 100kHz, the step value is 50kHz, the number of sweep points is 1000, and the signal is collected through the signal acquisition system and fed back to the central controller to calculate the calculated length L1 of the test cable, which is 495 meters.

[0093] L1 is less than L0, indicating that the cable under test has an aging area. Since more than 90% of the premature aging of cables is related to water, the water content in the cable under test can be calculated through the relationship between the lengths:

[0094] Water content = (L0-L1) / L0×100%

[0095] It should be noted that in actual operation, the length of the cable laid on site is unknown and usually has a large error. Therefore, the present invention fully considers the test under the condition of unknown cable length. A standard cable with an accurate length of 100 meters is provided as part of the tested cable. Through the same impedance sweep test, the cable length finally obtained by the frequency domain positioning method is 97 meters. The 97-meter cable is compared with the 100-meter cable to obtain a rough dielectric constant or change.

[0096] It can be seen that using standard cables and test cables to calculate length changes to evaluate cable aging is a very reliable and economical method.

[0097] Example 4

[0098] A cable aging treatment method comprises the following steps:

[0099] A1: Aging assessment, judging whether the aging management cable needs to be repaired through aging assessment of the cable aging management monitoring method;

[0100] As described in Example 3, L1<L0, the test cable is aged and needs to be repaired.

[0101] A2: Aging location: by using the cable aging management monitoring method, move the test position of the aging management cable to find the area with the larger change value of L1, which is the aging area;

[0102] According to the area of ​​the aging zone obtained in step A2, select the injection end of the repair liquid. If the aging zone is close to the current test end, only connect the repair device for repair; if the aging zone is close to the end of the cable to be tested, choose to inject the repair liquid at the end. This solution can greatly improve the repair efficiency, especially when the cable is particularly long and the overall aging is not obvious, but the local aging is serious, only local repair is required, which can save the repair liquid.

[0103] A3: Monitoring and repair: drilling holes or adding terminals at the front and rear ends of the aging area until they touch the metal layer or the armor layer, injecting repair liquid to eliminate moisture and fill the deterioration gaps. The repair process can be started regularly or the repair degree can be monitored in real time through the cable aging management monitoring method until the repair is completed;

[0104] Since the cable frequency domain positioning method can also provide continuous status information at any position of the cable, there will be a large mutation point for a certain area with high water content. Therefore, the aging treatment of the present invention can be combined to inject chemical liquid into the cable body for repair. During this process, the frequency domain positioning method can continue to be used for monitoring. After the chemical liquid enters the position where the mutation point occurs, the intensity information presented by the mutation point will gradually weaken as the repair process proceeds, thereby achieving effective and active monitoring of the aging repair process. By observing the changes in the total length of the cable, the improvement of the aging state of the entire cable can be observed, such as the length of 495 meters gradually approaching the length of 500 meters.

[0105] A4: Insulation seal.

[0106] It should be noted that during the monitoring and repair process, since the DDS continuously outputs high-frequency signals, the capacitive insulation layer of the cable generates a capacitive current, which plays a role in optimizing the repair. On the one hand, the capacitive current causes the capacitive layer to heat up, and heating is conducive to the flow of chemical liquids. On the other hand, under the electric field structure, the chemical liquid can better penetrate the capacitive layer. Of course, the repair process is relatively slow, so the monitoring process can be real-time or timed, such as monitoring once every 20 minutes. If continuous heating is required during the repair process, impedance spectrum testing and calculation of cable aging can be carried out, or the output of a single frequency point can be carried out, such as the continuous output of a 100kHz signal, to achieve a heating effect.

[0107] Since the entire hardware architecture in Example 2 can be digitally controlled, the above process can be completed through a computer program.

[0108] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for monitoring cable aging, characterized in that: The method includes an aging assessment, which can assess the aging condition of the cable, and includes the following steps: S1: Assemble the cable to be tested with a standard cable of fixed length to form a tested cable, wherein the standard cable has a stable dielectric constant and length; S2: The output signal source of the DDS signal generator passes through the power amplifier and then through the tested cable; S3: Obtain the calculated length L1 of the tested cable by frequency domain analysis of impedance spectrum or phase spectrum or time domain reflection method including power energy; S4: judging whether the cable is aged or the degree of cable aging by comparing the calculated length L1 of the tested cable with the actual length L0 of the tested cable: when L1=L0, the aging control cable has not aged; when L1<L0, the aging control cable has aged; the smaller L1 is, the more serious the aging phenomenon is; The cable aging treatment method comprises the following steps: A1: Determine whether the aging management cable needs to be repaired through the aging assessment; A2: Aging location: Move the test position of the aging control cable to find the area with a larger L1 change value, which is the aging area; A3: Monitoring and repairing: drilling holes or adding terminals at the front and rear ends of the aging area until they touch the metal layer or the armor layer, injecting repair liquid to eliminate moisture and fill the deteriorated gaps. The repair process can be started regularly or the repair degree can be monitored in real time until the repair is completed; A4: Insulation seal; In the step A3, before injecting the repair liquid, an input gas is charged for a certain period of time, and the input gas includes one or more of pure air, helium, SF6 gas, argon gas, and hydrophilic chemical gas; The repair liquid is one or more of insulating oil, organic silicon, phenylmethyldialkoxysilane (PhMeSi(OR) 2 ), phenylmethyldimethoxysilane (PhMeSi(OMe) 2 ), titanium dioxide, silicone rubber liquid, siloxane, hydrophobic silica liquid, and super hydrophobic silica liquid; In the A3: monitoring and repair step, current is passed through the cable core to generate heat and electric field to heat the insulation layer.

2. A method for monitoring cable aging according to claim 1, characterized in that: During the cable repair process, the S3 step can be started regularly or monitored in real time to obtain the calculated length L1 of the test cable. The change of L1 can determine the repair degree of the aging management cable. The closer the value of L1 is to L0, the closer the repair is to completion.

3. A monitoring device using the method of claim 1 or 2 comprises: Central controller, monitoring unit, tested cable; the monitoring unit includes a signal acquisition system, a DDS signal generator, and a power amplifier; the central controller is connected to the signal acquisition system and the DDS signal generator respectively; the DDS signal generator is connected to the power amplifier, and the tested cable is connected to the signal acquisition system and the power amplifier respectively.

4. The cable aging management monitoring device according to claim 3 is characterized in that: The power amplifier output and the acquisition system can be single-channel, i.e., single-core cable monitoring, or multi-channel, and can monitor three-phase or multi-phase cables.

5. A cable aging treatment device using the method described in claim 1, characterized in that: The device comprises: Central controller, tested cables; The monitoring unit according to claim 3; High frequency heating element; Inflating unit: includes a relay and a compressor connected in sequence; Repair liquid injection unit: including a repair liquid injection pump, an injection valve, a flow monitor, and a multi-phase synchronous valve connected in sequence; The central controller is connected to the monitoring unit and the inflation unit respectively; the tested cable is connected to the monitoring unit, the high-frequency heating element and the repair liquid injection unit respectively; The power amplifier is connected to the high-frequency heating element; The relay is connected to the central controller, the compressor is connected to the repair liquid injection pump, and the multi-phase synchronous valve is connected to the cable to be tested.

6. The cable aging treatment device according to claim 5, characterized in that: The device also includes a negative pressure unit.

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