Method, device, electronic equipment, system and storage medium for judging cable fault

Abstract

The application provides a cable fault judgment method, device, electronic equipment, system and storage medium. The method comprises the following steps: when local discharge of a cable joint of a detected cable is detected for the first time, a first insulation temperature and a first initial voltage of the cable joint at a current surface temperature are obtained; the cable joint is heated to different surface temperatures, and a second insulation temperature of the cable joint at each surface temperature is obtained; the power supply voltage of the cable joint is adjusted at each second insulation temperature, and the power supply voltage at which the cable joint generates local discharge at the second insulation temperature is recorded as a corresponding second initial voltage; based on the first insulation temperature, the first initial voltage, all second insulation temperatures and all second initial voltages, a change trend of the initial voltage of the cable joint when local discharge occurs with the insulation temperature is obtained; and whether the detected cable has a fault is judged according to the change trend. The application can effectively improve the accuracy of fault judgment of the detected cable.

Description

Technical Field

[0001] This invention relates to the field of cable fault diagnosis technology, and in particular to a method, apparatus, electronic device, system and storage medium for diagnosing cable faults. Background Technology

[0002] With the rapid development of the economy and society and the continuous improvement of urbanization, my country's electricity demand is constantly increasing. Therefore, the construction of urban power transmission lines is of great significance to meeting the needs of urban economic development. However, due to the scarcity of urban land resources, it is often difficult to construct overhead power transmission corridors, and the construction of such corridors may also negatively impact the urban landscape.

[0003] Therefore, high-voltage transmission cables, which offer high utilization rates of transmission corridors and are environmentally friendly, are currently widely used in the construction of urban power transmission lines. However, during the actual construction of high-voltage power cable lines, defects in the cables and their accessories can arise from the construction process, manufacturing techniques, and product quality. Consequently, during the subsequent operation of the high-voltage power cable lines, under the combined effects of electric fields, thermal fields, and mechanical forces, these defects can trigger partial discharge in the high-voltage cables, eventually leading to breakdown faults. Therefore, conducting partial discharge acceptance tests on completed high-voltage cables is essential. This acceptance test can effectively prevent high-voltage cables from operating with defects, thereby significantly reducing the failure rate of high-voltage cables.

[0004] In existing technologies, partial discharge acceptance tests on high-voltage cables are typically conducted on cables without load under AC power. However, this method has the following drawbacks: when there are strong interference sources around the test line, such as converter stations and signal towers, the test itself will be affected by electromagnetic waves from the surrounding environment, easily misinterpreting signals outside the cable as partial discharge defects, thus leading to misjudgments of defects. Summary of the Invention

[0005] This invention provides a method, apparatus, electronic device, system, and storage medium for judging cable faults, in order to solve the problem in the prior art that the accuracy of test results may be low due to the influence of strong interference sources around the test line when conducting partial discharge acceptance tests on high-voltage cables.

[0006] In a first aspect, embodiments of the present invention provide a method for determining cable faults, including:

[0007] When partial discharge is first detected at the cable joint of the cable under test, the first insulation temperature and the first initial voltage of the cable joint at the current surface temperature are obtained.

[0008] The cable joint is heated to different surface temperatures, and a second insulation temperature of the cable joint is obtained at each surface temperature;

[0009] The power supply voltage of the cable joint is adjusted at each second insulation temperature, and the power supply voltage at which the cable joint causes partial discharge at that second insulation temperature is recorded as the corresponding second initial voltage.

[0010] Based on the first insulation temperature, the first initial voltage, all second insulation temperatures, and all second initial voltages, the trend of the initial voltage as a function of insulation temperature when partial discharge occurs at the cable joint is obtained.

[0011] The test cable is judged to have a fault based on the changing trend.

[0012] In one possible implementation, determining whether the detected cable has failed based on the changing trend includes:

[0013] When the trend of change is such that the initial voltage of the cable joint when partial discharge occurs changes in the opposite direction with the change of insulation temperature, it is determined that the cable under test has a fault.

[0014] In one possible implementation, obtaining the second insulation temperature of the cable joint at each surface temperature includes:

[0015] Temperature inversion calculations are performed based on the surface temperature of each surface of the cable joint and a preset thermal circuit model to obtain the second insulation temperature of the cable joint at each surface temperature.

[0016] Secondly, embodiments of the present invention provide a cable fault diagnosis device, comprising:

[0017] The initial data acquisition module is used to acquire the first insulation temperature and the first initial voltage of the cable joint at the current surface temperature when partial discharge is first detected at the cable joint of the cable under test.

[0018] An insulation temperature acquisition module is used to heat the cable joint to different surface temperatures and acquire a second insulation temperature of the cable joint at each surface temperature;

[0019] An initial voltage acquisition module is used to adjust the power supply voltage of the cable joint at each second insulation temperature, and to record the power supply voltage at which the cable joint causes partial discharge at that second insulation temperature as the corresponding second initial voltage.

[0020] The trend determination module is used to obtain the trend of the initial voltage of the cable joint when partial discharge occurs with the insulation temperature based on the first insulation temperature, the first initial voltage, all second insulation temperatures and all second initial voltages.

[0021] The cable fault detection module is used to determine whether the detected cable has a fault based on the changing trend.

[0022] Thirdly, embodiments of the present invention provide an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method as described in the first aspect or any possible implementation of the first aspect.

[0023] Fourthly, embodiments of the present invention provide a cable fault diagnosis system, including the electronic equipment described in the third aspect above, and further including: a partial discharge measuring device, a temperature control device, and a pressurizing device;

[0024] One end of the partial discharge measuring device is connected to the cable joint of the cable under test, and the other end of the partial discharge measuring device is connected to the electronic device, used to monitor whether partial discharge occurs at each cable joint of the cable under test;

[0025] One end of the temperature control device is connected to the cable connector of the cable being tested, and the other end of the temperature control device is connected to the electronic device, used to collect the surface temperature of each cable connector and heat each cable connector to a different surface temperature.

[0026] One end of the pressurizing device is connected to the electronic device, and the other end of the pressurizing device is connected to the first end of the cable under test. The metal shielding layer of the second end of the cable under test is grounded. The pressurizing device is used to apply an adjustable power supply voltage to the cable under test.

[0027] In one possible implementation, the partial discharge measuring device includes: a partial discharge control unit, an optical fiber, and partial discharge detection sensors and partial discharge detection units corresponding to each of the cable connectors;

[0028] For each partial discharge detection sensor, one end of the sensor is connected to the corresponding cable connector, and the other end is connected to one end of the corresponding partial discharge detection unit, which is used to detect partial discharge in the corresponding cable connector and generate a first electrical signal accordingly.

[0029] For each partial discharge detection unit, the other end of the partial discharge detection unit is connected to one end of the partial discharge control unit through the optical fiber, which is used to convert the first electrical signal into an optical signal.

[0030] The other end of the partial discharge control unit is connected to the electronic device. The partial discharge control unit is used to convert the optical signal output by each partial discharge detection unit into a corresponding second electrical signal and send it to the electronic device. The electronic device is also used to generate a control signal based on the second electrical signal. The partial discharge control unit is also used to control each partial discharge detection sensor to start or stop performing partial discharge detection on the corresponding cable joint based on the control signal sent by the electronic device.

[0031] In one possible implementation, the temperature control device includes: a heating belt, a temperature acquisition card, and a temperature controller;

[0032] The heating band is installed at each cable joint for heating the corresponding cable joint;

[0033] The temperature acquisition card is installed at each cable joint, with its first end connected to the electronic device and its second end connected to the corresponding cable joint, for acquiring the surface temperature of the corresponding cable joint.

[0034] The temperature controller is located at each cable joint, with its first end connected to the electronic device and its second end connected to the heating band. It is used to control the heating temperature of the heating band based on the temperature control signal emitted by the electronic device, so as to heat the corresponding cable joint to different surface temperatures.

[0035] In one possible implementation, the pressurizing device includes: a variable power supply, a frequency conversion control unit, an excitation transformer, a high-voltage resonant reactor, an isolation impedance device, a voltage measurement and display device, and a high-voltage measurement and voltage divider device;

[0036] The variable power supply is connected to the input terminal of the frequency conversion control unit as an input power supply;

[0037] The output terminal of the frequency conversion control unit is connected to the primary side of the excitation transformer;

[0038] One end of the secondary side of the excitation transformer is grounded, and the other end is connected to the input terminal of the high-voltage resonant reactor;

[0039] The output terminal of the high-voltage resonant reactor is connected to the first terminal of the high-voltage measuring voltage divider and the input terminal of the isolation impedance device, respectively.

[0040] The output terminal of the isolation impedance is connected to the first end of the cable under test;

[0041] The second end of the high-voltage measuring voltage divider is connected to one end of the voltage measuring and display device, and the third end is connected to one end of the secondary side of the excitation transformer.

[0042] The other end of the voltage measurement and display device is connected to the input terminal of the frequency conversion control unit and then to the electronic device.

[0043] Fifthly, embodiments of the present invention provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the method as described in the first aspect or any possible implementation thereof.

[0044] This invention provides a method, apparatus, electronic device, system, and storage medium for determining cable faults. Unlike existing technologies that assume a cable fault simply by detecting partial discharge, this invention determines the trend of the initial voltage of each cable joint during partial discharge based on the insulation temperature and the corresponding initial voltage. It then uses this trend to determine whether the cable is faulty. By observing this trend, it effectively identifies whether the source of the partial discharge originates from the cable itself or from other strong interference sources, thereby improving the accuracy of fault determination and the precision of partial discharge acceptance testing. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a flowchart illustrating the implementation of the cable fault judgment method provided in this embodiment of the invention.

[0047] Figure 2 This is a schematic diagram of the structure of the cable transient thermal circuit model provided in the embodiment of the present invention;

[0048] Figure 3 This is a schematic diagram of the cable fault detection device provided in an embodiment of the present invention;

[0049] Figure 4 This is a schematic diagram of an electronic device provided in an embodiment of the present invention;

[0050] Figure 5 This is a schematic diagram of the cable fault judgment system provided in an embodiment of the present invention;

[0051] Figure 6This is a schematic diagram of the structure of a cable fault detection system provided in another embodiment of the present invention;

[0052] Figure 7 This is a schematic diagram illustrating the relationship between the initial voltage and the insulation temperature provided in an embodiment of the present invention. Detailed Implementation

[0053] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0054] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments will be described below in conjunction with the accompanying drawings.

[0055] Figure 1 The flowchart for implementing the cable fault judgment method provided in this embodiment of the invention is as follows: Figure 1 As shown, the cable fault judgment method provided by the embodiments of the present invention is described in detail below: The method includes:

[0056] Step 101: When partial discharge is first detected at the cable joint of the cable under test, obtain the first insulation temperature and the first initial voltage of the cable joint at the current surface temperature.

[0057] In step 101, when partial discharge is first detected at the cable joint of the cable being tested, the first insulation temperature and the first initial voltage of the cable joint currently experiencing partial discharge are acquired at the current surface temperature. For example, the current surface temperature can be the ambient temperature or the measured surface temperature of the cable joint experiencing partial discharge. The first insulation temperature can be calculated based on this current surface temperature through temperature inversion. Furthermore, the first insulation temperature can be the temperature at the middle position of the insulation layer at the cable joint experiencing partial discharge; it can also be the temperature of the insulation layer near the cable core at the cable joint experiencing partial discharge, and this application does not limit this. In this embodiment, acquiring the first insulation temperature and the first initial voltage of the cable joint experiencing partial discharge at the current surface temperature facilitates subsequent determination based on these acquired data whether the partial discharge phenomenon is occurring in the cable being tested itself, thereby facilitating effective judgment of the cable's condition.

[0058] Step 102: Heat the cable joint to different surface temperatures and obtain the second insulation temperature of the cable joint at each surface temperature.

[0059] In step 102, the cable joint experiencing partial discharge is heated to different surface temperatures, and the second insulation temperature of the cable joint experiencing partial discharge is obtained at each surface temperature. For example, the different surface temperatures can be discontinuous temperature values, such as 20°C, 40°C, 60°C, etc.; or they can be continuous temperature values, which is not limited in this application. In this embodiment, by obtaining the second insulation temperature of the cable joint corresponding to different surface temperatures, it is beneficial to obtain the initial discharge voltage of the cable joint when partial discharge occurs based on each second insulation temperature test, thereby facilitating the subsequent effective judgment of the cable condition based on insulation temperature and voltage data.

[0060] In one possible implementation, obtaining the second insulation temperature of the cable joint at each surface temperature includes:

[0061] Temperature inversion calculations are performed based on the surface temperature of each cable joint and a preset thermal circuit model to obtain the second insulation temperature of the cable joint at each surface temperature.

[0062] In this embodiment, Figure 2 This is a schematic diagram of the structure of the cable transient thermal circuit model provided in an embodiment of the present invention, as shown below. Figure 2 As shown, since it is difficult to directly measure the temperature of the insulation layer in the cable under test, temperature inversion calculations can be performed based on the surface temperature of each cable joint and the thermal circuit model to obtain the second insulation temperature corresponding to each surface temperature of the cable joint. The established transient thermal circuit model of the cable is as follows. Figure 2 As shown, the thermal resistance of the cable core and aluminum sheath of the tested cable is ignored, and only the heat capacity is considered. C0 and T0 represent the heat capacity of the cable core and the corresponding outer surface temperature, respectively; C1-C n-3 and R1-R n-3 T1-T represent the heat capacity and thermal resistance of each layer of the cross-linked polyethylene layer and the inner and outer shielding layers, respectively. n-3 This indicates the outer surface temperature of each layer of the cross-linked polyethylene layer and the inner and outer shielding layers; C n-2 R n-2 and T n-2 These represent the heat capacity, thermal resistance, and outer surface temperature of the water-blocking strip, respectively; C n-1 Indicates the heat capacity of the aluminum sheath; C n R n-1 and T n-1 P represents the heat capacity, thermal resistance, and outer surface temperature of the outer sheath, respectively. s Joule heating, acting as a heating source per unit length, is the only heat source in the transient thermal circuit model of the cable. Since temperature sensors can be placed on the outer surface of the outer sheath, T... n-1Since the temperature is known, the second insulation temperature corresponding to each surface temperature can be calculated based on the outer surface temperature of the outer sheath, the applied heat source, and the heat capacity and thermal resistance of each layer.

[0063] Step 103: Adjust the power supply voltage of the cable joint at each second insulation temperature, and record the power supply voltage at which partial discharge occurs at the cable joint at that second insulation temperature as the corresponding second initial voltage.

[0064] In step 103, for each second insulation temperature, the power supply voltage of the cable joint can be adjusted at that second insulation temperature, and the second initial voltage of the cable joint corresponding to that second insulation temperature when partial discharge occurs is recorded. For example, the second initial voltage can be the power supply voltage corresponding to the cable joint when partial discharge occurs at each second insulation temperature. In this way, the initial discharge voltage corresponding to the cable joint when partial discharge occurs at different insulation temperatures is obtained, which is beneficial for subsequently determining whether the tested cable has a fault based on the changing trend between the insulation temperature and the initial discharge voltage.

[0065] Step 104: Based on the first insulation temperature, the first initial voltage, all second insulation temperatures, and all second initial voltages, obtain the trend of the initial voltage changing with the insulation temperature when partial discharge occurs at the cable joint.

[0066] In step 104, all acquired insulation temperatures and initial voltages are analyzed to obtain the trend of initial voltage variation with insulation temperature when partial discharge occurs at the cable joint. That is, the first insulation temperature, the first initial voltage, all second insulation temperatures, and all second initial voltages are analyzed to obtain the trend of initial voltage variation with insulation temperature when partial discharge occurs at the cable joint. This is helpful for subsequent determination based on this trend whether the partial discharge phenomenon is caused by the cable joint of the tested cable or other external environmental interference sources.

[0067] Step 105: Determine whether the cable under test has a fault based on the trend of change.

[0068] In step 105, the trend of the initial voltage change with insulation temperature when partial discharge occurs at the cable joint can be used to determine whether each cable joint on the tested cable is faulty, thereby further determining whether the tested cable is faulty. In this embodiment, this trend is used to determine whether the partial discharge phenomenon is occurring at the cable joint of the tested cable or at other external environmental interference sources, thereby achieving an effective judgment of the condition of the tested cable.

[0069] In one possible implementation, determining whether the tested cable has a fault based on the trend of change includes:

[0070] When the trend shows that the initial voltage at the cable joint undergoes partial discharge in the opposite direction to the change in insulation temperature, it is determined that the cable under test has a fault.

[0071] In this embodiment, Figure 7 This is a schematic diagram illustrating the relationship between initial voltage and insulation temperature provided in an embodiment of the present invention, as shown below. Figure 7 As shown, when the initial voltage of a cable joint experiencing partial discharge changes in the opposite direction to the change in insulation temperature, it is determined that the partial discharge is occurring at the cable joint of the cable under test, thus confirming a fault in the cable. For example, when the initial voltage of a cable joint experiencing partial discharge decreases as the insulation temperature increases, it is determined that the cable under test is faulty, thereby achieving an effective assessment of the cable's condition.

[0072] This invention provides a method for determining cable faults. By acquiring the insulation temperatures and corresponding initial partial discharge voltages of the cable joints during partial discharge, unlike existing technologies that assume a fault upon detecting partial discharge, this invention determines the trend of the initial voltage at each cable joint during partial discharge as a function of insulation temperature, based on the insulation temperatures and corresponding initial partial discharge voltages. This trend is then used to determine whether the cable under test is faulty. In this way, observing the trend effectively identifies whether the source of the partial discharge originates from the cable itself or other strong interference sources, thereby significantly improving the accuracy of fault determination and the precision of partial discharge acceptance tests on the cable.

[0073] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0074] The following are device embodiments of the present invention. For details not described in detail, please refer to the corresponding method embodiments described above.

[0075] Figure 3 This is a schematic diagram of the cable fault detection device provided in an embodiment of the present invention. For ease of explanation, only the parts related to the embodiment of the present invention are shown, and are described in detail below:

[0076] like Figure 3 As shown, the cable fault detection device 3 includes:

[0077] The initial data acquisition module 301 is used to acquire the first insulation temperature and the first initial voltage of the cable joint at the current surface temperature when partial discharge is first detected at the cable joint of the cable under test.

[0078] Insulation temperature acquisition module 302 is used to heat the cable joint to different surface temperatures and acquire the second insulation temperature of the cable joint at each surface temperature.

[0079] The initial voltage acquisition module 303 is used to adjust the power supply voltage of the cable joint at each second insulation temperature, and to record the power supply voltage at which partial discharge occurs at the cable joint at that second insulation temperature as the corresponding second initial voltage.

[0080] The trend determination module 304 is used to obtain the trend of the initial voltage of the cable joint during partial discharge with respect to the insulation temperature based on the first insulation temperature, the first initial voltage, all second insulation temperatures and all second initial voltages.

[0081] The cable fault diagnosis module 305 is used to determine whether the cable under test has a fault based on the trend of change.

[0082] This invention provides a cable fault diagnosis device, comprising: an initial data acquisition module 301, an insulation temperature acquisition module 302, an initial voltage acquisition module 303, a trend determination module 304, and a cable fault diagnosis module 305. By acquiring the insulation temperatures and corresponding initial partial discharge voltages of the cable joints of the cable under test during partial discharge, unlike existing technologies that determine a cable fault upon detecting partial discharge, this invention determines the trend of the initial voltage of each cable joint during partial discharge with respect to insulation temperature based on the insulation temperatures and corresponding initial partial discharge voltages, and determines whether the cable under test is faulty based on this trend. In this way, by observing the trend, it is possible to effectively determine whether the source of the partial discharge originates from the cable under test itself or from other strong interference sources, thereby effectively improving the accuracy of fault diagnosis for the cable under test and also improving the test precision during partial discharge acceptance testing of the cable under test.

[0083] In one possible implementation, the cable fault diagnosis module 305 is specifically used for:

[0084] When the trend shows that the initial voltage at the cable joint undergoes partial discharge in the opposite direction to the change in insulation temperature, it is determined that the cable under test has a fault.

[0085] In one possible implementation, the insulation temperature acquisition module 302 is specifically used for:

[0086] Temperature inversion calculations are performed based on the surface temperature of each cable joint and a preset thermal circuit model to obtain the second insulation temperature of the cable joint at each surface temperature.

[0087] Figure 4 This is a schematic diagram of an electronic device provided in an embodiment of the present invention. Figure 4 As shown, the electronic device 4 in this embodiment includes: a processor 40, a memory 41, and a computer program 42 stored in the memory 41 and executable on the processor 40. When the processor 40 executes the computer program 42, it implements the steps in the various cable fault judgment method embodiments described above, for example... Figure 1 Steps 101 to 105 are shown. Alternatively, when the processor 40 executes the computer program 42, it implements the functions of each module / unit in the above-described device embodiments, for example... Figure 3 The functions of modules 301 to 305 are shown.

[0088] For example, the computer program 42 can be divided into one or more modules / units, which are stored in the memory 41 and executed by the processor 40 to complete the present invention. The one or more modules / units can be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program 42 in the electronic device 4. For example, the computer program 42 can be divided into... Figure 3 Modules 301 to 305 are shown.

[0089] The electronic device 4 can be a desktop computer, laptop, handheld computer, or cloud server, etc. The electronic device 4 may include, but is not limited to, a processor 40 and a memory 41. Those skilled in the art will understand that... Figure 4 This is merely an example of electronic device 4 and does not constitute a limitation on electronic device 4. It may include more or fewer components than shown, or combine certain components, or different components. For example, the electronic device may also include input / output devices, network access devices, buses, etc.

[0090] The processor 40 may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0091] The memory 41 can be an internal storage unit of the electronic device 4, such as a hard disk or memory. The memory 41 can also be an external storage device of the electronic device 4, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card. Furthermore, the memory 41 can include both internal and external storage units of the electronic device 4. The memory 41 is used to store the computer program and other programs and data required by the electronic device. The memory 41 can also be used to temporarily store data that has been output or will be output.

[0092] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0093] This invention also provides a cable fault diagnosis system. Figure 5 This is a schematic diagram of the cable fault diagnosis system provided in an embodiment of the present invention, as shown below. Figure 5 As shown, the system includes the electronic device 4 described above, and also includes: a partial discharge measuring device 51, a temperature control device 52, and a pressurizing device 53.

[0094] One end of the partial discharge measuring device 51 is connected to the cable joint 61 of the cable under test, and the other end of the partial discharge measuring device 51 is connected to the electronic device 4 to monitor whether partial discharge occurs at each cable joint 61 of the cable under test.

[0095] One end of the temperature control device 52 is connected to the cable connector 61 of the cable being tested, and the other end of the temperature control device 52 is connected to the electronic device 4, which is used to collect the surface temperature of each cable connector 61 and heat each cable connector 61 to a different surface temperature.

[0096] One end of the pressurizing device 53 is connected to the electronic device 4, and the other end of the pressurizing device 53 is connected to the first end of the cable under test. The metal shielding layer 62 of the second end of the cable under test is grounded. The pressurizing device 53 is used to apply an adjustable power supply voltage to the cable under test.

[0097] In this embodiment, the pressurizing device 53 enables controllable adjustment of the voltage applied to the cable under test. The partial discharge measuring device 51 measures the partial discharge of the cable under test. Given the long length of the cable and the large number of intermediate cable joints 61, a high-frequency current measurement method can be used to simultaneously measure the partial discharge of multiple intermediate cable joints 61. Additionally, the temperature control device 52 heats the cable joints 61 of the cable under test to different surface temperatures.

[0098] In one possible implementation, Figure 6 This is a schematic diagram of the structure of a cable fault detection system provided in another embodiment of the present invention, as shown below. Figure 6 As shown, the partial discharge measurement device 51 includes: a partial discharge control unit 511, an optical fiber 512, and partial discharge detection sensors 513 and partial discharge detection units 514 corresponding to each cable connector.

[0099] For each partial discharge detection sensor 513, one end of the partial discharge detection sensor 513 is connected to the corresponding cable connector 61, and the other end is connected to one end of the corresponding partial discharge detection unit 514, for performing partial discharge detection on the corresponding cable connector 61 and generating a first electrical signal accordingly.

[0100] For each partial discharge detection unit 514, the other end of the partial discharge detection unit 514 is connected to one end of the partial discharge control unit 511 via an optical fiber 512, which is used to convert the first electrical signal into an optical signal.

[0101] The other end of the partial discharge control unit 511 is connected to the electronic device 4, which is used to convert the optical signal output by each partial discharge detection unit 514 into a corresponding second electrical signal and send it to the electronic device 4; the electronic device 4 is also used to generate a control signal based on the second electrical signal; the partial discharge control unit 511 is also used to control each partial discharge detection sensor 513 to start or stop performing partial discharge detection on the corresponding cable connector 61 based on the control signal sent by the electronic device 4.

[0102] In this embodiment, as Figure 6As shown, during partial discharge testing, partial discharge detection sensors 513 are respectively installed at the locations of the cable under test where partial discharge detection is required, i.e., at each cable joint. Each partial discharge detection sensor 513 is used to start or stop partial discharge detection according to the control signal issued by the electronic device 4. The partial discharge detection result of each partial discharge detection sensor 513 is a first electrical signal. The partial discharge detection sensor 513 detects the first electrical signal at the grounding wire of the cable under test, converts it into an optical signal through the partial discharge detection unit 514, and transmits it through the uplink optical fiber 512 port to the previous partial discharge detection unit 514, and so on, until it reaches the partial discharge control unit 511. The partial discharge control unit 511 converts the received optical signal into a second electrical signal and sends it to the electronic device 4, where the electronic device 4 processes the data. For example, the transmission method can be: sending to the electronic device 4 via a USB interface. The first electrical signal and the second electrical signal are essentially the same. The conversion between the first electrical signal and the second electrical signal is to ensure that the data can be transmitted in the optical fiber 512 without interference, thereby ensuring the reliability and accuracy of data transmission.

[0103] In one possible implementation, such as Figure 6 As shown, the temperature control device 52 includes: a heating belt 521, a temperature acquisition card 522, and a temperature controller 523.

[0104] Heating strip 521 is provided at each cable joint 61 for heating the corresponding cable joint 61.

[0105] Temperature acquisition card 522 is installed at each cable connector 61. The first end is connected to electronic device 4, and the second end is connected to the corresponding cable connector 61 to acquire the surface temperature of the corresponding cable connector 61.

[0106] Temperature controller 523 is installed at each cable joint 61. The first end is connected to electronic device 4 and the second end is connected to heating belt 521. It is used to control the heating temperature of heating belt 521 according to the temperature control signal issued by electronic device 4, so as to heat the corresponding cable joint 61 to different surface temperatures.

[0107] In this embodiment, given that the temperature field of medium and high voltage cable joints has very similar axial temperatures of the cable core, resembling a bell-shaped distribution, diffuses from the hot spot of the joint to both sides, with the temperature change extending to the nearby cable body, the extension length varying depending on the type. This distribution characteristic can be solved using the IEC60853 thermal circuit model. Temperature inversion can be performed using this model to convert the measured surface temperature of the cable joint into the corresponding insulation temperature. For example, the cable joint 61 of the cable under test can be heated using a heating tape 521, and the surface temperature of the cable joint can be measured using a temperature acquisition card 522.

[0108] In one possible implementation, such as Figure 6 As shown, the pressurization device 53 includes: a variable power supply 531, a frequency conversion control unit 532, an excitation transformer 533, a high-voltage resonant reactor 534, an isolation impedance device 535, a voltage measurement and display device 536, and a high-voltage measurement and voltage divider device 537.

[0109] The variable power supply 531 is connected to the input terminal of the frequency converter control unit 532 as an input power supply.

[0110] The output terminal of the frequency conversion control unit 532 is connected to the primary side of the excitation transformer 533.

[0111] One end of the secondary side of the excitation transformer 533 is grounded, and the other end is connected to the input terminal of the high-voltage resonant reactor 534.

[0112] The output terminal of the high-voltage resonant reactor 534 is connected to the first terminal of the high-voltage measuring voltage divider 537 and the input terminal of the isolation impedance device 535, respectively.

[0113] The output of the isolation impedance 535 is connected to the first end of the cable being tested.

[0114] The second end of the high voltage measuring voltage divider 537 is connected to one end of the voltage measuring and display device 536, and the third end of the high voltage measuring voltage divider 537 is connected to one end of the secondary side of the excitation transformer 533.

[0115] The other end of the voltage measurement and display device 536 is connected to the input terminal of the frequency converter control unit 532 and then connected to the electronic device 4.

[0116] In this embodiment, for example, the variable power source 531 can be a substation power source or a generator vehicle power source; this application does not limit this to any particular type. Figure 6 As shown, the high-voltage measuring voltage divider 537 can be composed of two capacitors, C1 and C2. The variable power supply 531 is connected to the frequency converter control unit 532 as the input power supply. The output voltage of the control unit is boosted by the excitation transformer 533 and then applied to the high-voltage end of the cable under test via the high-voltage resonant reactor 534 and the isolation impedance device 535. The metal shielding layer 62 at the other end of the cable under test is grounded. For cable lines with outdoor terminals, the frequency converter resonant device can be directly connected to the outdoor terminal, with the other end of the line grounded.

[0117] This invention provides a cable fault diagnosis system. By acquiring the insulation temperatures and corresponding initial partial discharge voltages of the cable joints during partial discharge, unlike existing technologies that assume a fault upon detecting partial discharge, this invention determines the trend of the initial voltage of each cable joint during partial discharge as a function of insulation temperature, based on the insulation temperatures and corresponding initial partial discharge voltages. This trend is then used to determine whether the cable under test is faulty. In this way, observing the trend effectively identifies whether the source of the partial discharge originates from the cable itself or other strong interference sources, thereby significantly improving the accuracy of fault diagnosis and the precision of partial discharge acceptance testing of the cable.

[0118] Furthermore, this invention has a wide range of applications. For example, it can be applied to cable completion acceptance testing, cable temperature monitoring technology, partial discharge simulation technology for cable tunnels, or simulation technology of the impact of cable structure on cable condition, etc., and this application does not limit it to these applications. This invention utilizes the relationship between the initiation voltage and insulation temperature of a partially discharged cable under test. Based on this correlation, it determines whether the partial discharge originates from the insulation layer of the cable under test, thereby effectively eliminating noise signals from outside the cable and achieving accurate assessment of the cable condition. Compared to traditional methods, this method is more reliable, more accurate in judging the cable condition, and can quickly obtain correct results with higher efficiency. In terms of technical effects, this invention can quickly determine the cable condition, and the results obtained are not only reliable but also simple and fast, which is significant in terms of safety, efficiency, and economy.

[0119] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0120] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0121] In the embodiments provided by this invention, it should be understood that the disclosed devices / electronic devices and methods can be implemented in other ways. For example, the device / electronic device embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0122] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0123] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0124] If the integrated module / unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the above embodiments of the cable fault judgment methods. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0125] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A method for diagnosing cable faults, characterized in that, include: When partial discharge is first detected at the cable joint of the cable under test, the first insulation temperature and the first initial voltage of the cable joint at the current surface temperature are obtained. The cable joint is heated to different surface temperatures, and a second insulation temperature of the cable joint is obtained at each surface temperature; The power supply voltage of the cable joint is adjusted at each second insulation temperature, and the power supply voltage at which the cable joint causes partial discharge at that second insulation temperature is recorded as the corresponding second initial voltage. Based on the first insulation temperature, the first initial voltage, all second insulation temperatures, and all second initial voltages, the trend of the initial voltage as a function of insulation temperature when partial discharge occurs at the cable joint is obtained. The test cable is judged to have a fault based on the changing trend.

2. The method for determining cable faults according to claim 1, characterized in that, The step of determining whether the tested cable has a fault based on the changing trend includes: When the trend of change is such that the initial voltage of the cable joint when partial discharge occurs changes in the opposite direction with the change of insulation temperature, it is determined that the cable under test has a fault.

3. The method for determining cable faults according to claim 1, characterized in that, The process of obtaining the second insulation temperature of the cable joint at each surface temperature includes: Temperature inversion calculations are performed based on the surface temperature of each surface of the cable joint and a preset thermal circuit model to obtain the second insulation temperature of the cable joint at each surface temperature.

4. A cable fault diagnosis device, characterized in that, include: The initial data acquisition module is used to acquire the first insulation temperature and the first initial voltage of the cable joint at the current surface temperature when partial discharge is first detected at the cable joint of the cable under test. An insulation temperature acquisition module is used to heat the cable joint to different surface temperatures and acquire a second insulation temperature of the cable joint at each surface temperature; An initial voltage acquisition module is used to adjust the power supply voltage of the cable joint at each second insulation temperature, and to record the power supply voltage at which the cable joint causes partial discharge at that second insulation temperature as the corresponding second initial voltage. The trend determination module is used to obtain the trend of the initial voltage of the cable joint when partial discharge occurs with the insulation temperature based on the first insulation temperature, the first initial voltage, all second insulation temperatures and all second initial voltages. The cable fault detection module is used to determine whether the detected cable has a fault based on the changing trend.

5. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method as described in any one of claims 1 to 3 above.

6. A cable fault diagnosis system, characterized in that, The electronic device as described in claim 5 further includes: a partial discharge measuring device, a temperature control device, and a pressurizing device; One end of the partial discharge measuring device is connected to the cable joint of the cable under test, and the other end of the partial discharge measuring device is connected to the electronic device, used to monitor whether partial discharge occurs at each cable joint of the cable under test; One end of the temperature control device is connected to the cable connector of the cable being tested, and the other end of the temperature control device is connected to the electronic device, used to collect the surface temperature of each cable connector and heat each cable connector to a different surface temperature. One end of the pressurizing device is connected to the electronic device, and the other end of the pressurizing device is connected to the first end of the cable under test. The metal shielding layer of the second end of the cable under test is grounded. The pressurizing device is used to apply an adjustable power supply voltage to the cable under test.

7. The cable fault diagnosis system according to claim 6, characterized in that, The partial discharge measurement device includes: a partial discharge control unit, an optical fiber, and partial discharge detection sensors and partial discharge detection units corresponding to each of the cable joints; For each partial discharge detection sensor, one end of the sensor is connected to the corresponding cable connector, and the other end is connected to one end of the corresponding partial discharge detection unit, which is used to detect partial discharge in the corresponding cable connector and generate a first electrical signal accordingly. For each partial discharge detection unit, the other end of the partial discharge detection unit is connected to one end of the partial discharge control unit through the optical fiber, which is used to convert the first electrical signal into an optical signal. The other end of the partial discharge control unit is connected to the electronic device. The partial discharge control unit is used to convert the optical signal output by each partial discharge detection unit into a corresponding second electrical signal and send it to the electronic device. The electronic device is also used to generate a control signal based on the second electrical signal. The partial discharge control unit is also used to control each partial discharge detection sensor to start or stop performing partial discharge detection on the corresponding cable joint based on the control signal sent by the electronic device.

8. The cable fault diagnosis system according to claim 6, characterized in that, The temperature control device includes: a heating belt, a temperature acquisition card, and a temperature controller; The heating band is installed at each cable joint for heating the corresponding cable joint; The temperature acquisition card is installed at each cable joint, with its first end connected to the electronic device and its second end connected to the corresponding cable joint, for acquiring the surface temperature of the corresponding cable joint. The temperature controller is located at each cable joint, with its first end connected to the electronic device and its second end connected to the heating band. It is used to control the heating temperature of the heating band based on the temperature control signal emitted by the electronic device, so as to heat the corresponding cable joint to different surface temperatures.

9. The cable fault diagnosis system according to claim 6, characterized in that, The pressurization device includes: a variable power supply, a frequency conversion control unit, an excitation transformer, a high-voltage resonant reactor, an isolation impedance device, a voltage measurement and display device, and a high-voltage measurement and voltage divider device; The variable power supply is connected to the input terminal of the frequency conversion control unit as an input power supply; The output terminal of the frequency conversion control unit is connected to the primary side of the excitation transformer; One end of the secondary side of the excitation transformer is grounded, and the other end is connected to the input terminal of the high-voltage resonant reactor; The output terminal of the high-voltage resonant reactor is connected to the first terminal of the high-voltage measuring voltage divider and the input terminal of the isolation impedance device, respectively. The output terminal of the isolation impedance is connected to the first end of the cable under test; The second end of the high-voltage measuring voltage divider is connected to one end of the voltage measuring and display device, and the third end is connected to one end of the secondary side of the excitation transformer. The other end of the voltage measurement and display device is connected to the input terminal of the frequency conversion control unit and then to the electronic device.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method as described in any one of claims 1 to 3 above.

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