Cable terminal defect detection method, device and equipment based on microwave reflection, medium and product
By constructing a microwave reflection multilayer dielectric model and calculating the equivalent reflection coefficient, the limitations of existing cable terminal detection methods are overcome, and fast, accurate and non-destructive cable terminal defect detection is achieved, and different types of defects can be identified.
Patent Information
- Application Number
- CN202510673385.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-23
- Publication Date
- 2025-09-05
AI Technical Summary
Existing cable terminal defect detection methods have limitations in terms of safety, accuracy and efficiency, making it difficult to achieve fast, accurate and non-destructive detection.
A cable terminal defect detection method based on microwave reflection constructs a microwave reflection multilayer dielectric model, calculates the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal, and determines the defect type based on the value range of the reflection coefficient.
It realizes fast, accurate and non-destructive cable terminal defect detection, and can identify defects such as air gap defects, mixed conductive impurities and moisture ingress, with the advantages of non-contact, non-destructive and high-sensitivity detection.
Smart Images
Figure CN120594558A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of cable detection technology, and in particular to a method, device, equipment, medium and product for detecting cable terminal defects based on microwave reflection. Background Art
[0002] Cable terminals connect cables to electrical equipment, providing excellent insulation and ensuring safe and reliable operation of cable systems. However, during the installation and fabrication of cable terminals, improper handling often leads to defects such as surface damage to the cross-linked polyethylene (XLPE), the intrusion of conductive impurities at the interface, and moisture ingress. At high operating voltages, the electric field at these defects is severely distorted, making partial discharge highly likely. This can ultimately lead to insulation failure at the cable terminal and cause serious accidents.
[0003] Existing detection methods for internal defects in cable terminals include partial discharge, ultrasonic, infrared thermal imaging and X-ray detection. However, these existing detection methods have many limitations in terms of safety, accuracy and efficiency. Summary of the Invention
[0004] The purpose of this application is to provide a cable terminal defect detection method, device, equipment, medium and product based on microwave reflection, which can realize fast, accurate and non-destructive detection of cable terminal defects.
[0005] To achieve the above objectives, this application provides the following solutions:
[0006] In a first aspect, the present application provides a cable terminal defect detection method based on microwave reflection, comprising:
[0007] Construct a microwave reflection multilayer dielectric model based on the multilayer structure of the cable terminal;
[0008] Based on a microwave reflection multilayer dielectric model, an equivalent reflection coefficient calculation model is constructed at the interface between a rectangular waveguide and a cable terminal. The rectangular waveguide is used to transmit microwaves into the cable terminal. The microwaves propagate inside the cable terminal and are reflected at each interface.
[0009] Calculate the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal according to the equivalent reflection coefficient calculation model;
[0010] The defect type of the cable terminal is determined according to the value range of the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal.
[0011] Optionally, the microwave reflection multilayer dielectric model is a four-layer dielectric structure, and the four-layer dielectric structure is silicone rubber, defects, XLPE and metal arranged in sequence; microwaves are incident vertically from the silicone rubber surface and reflected at the third interface, the second interface and the first interface in sequence; the first interface is the interface between the silicone rubber and the defect, the second interface is the interface between the defect and the XLPE, and the third interface is the interface between the XLPE and the metal.
[0012] Optionally, based on a microwave reflection multilayer dielectric model, an equivalent reflection coefficient calculation model at the interface between the rectangular waveguide and the cable terminal is constructed, specifically including:
[0013] According to the equivalent wave impedance at each interface in the microwave reflection multilayer dielectric model, an equivalent reflection coefficient calculation model at the interface between the rectangular waveguide and the cable terminal is obtained; each interface includes the first interface, the second interface and the third interface.
[0014] Optionally, according to the equivalent wave impedance at each interface in the microwave reflection multilayer dielectric model, an equivalent reflection coefficient calculation model at the interface between the rectangular waveguide and the cable terminal is obtained, specifically including:
[0015] The equivalent reflection coefficient of the third interface to the second interface is:
[0016]
[0017] Where R3′ is the equivalent reflection coefficient of the third interface to the second interface, R3 is the reflection coefficient of the third interface, j is the imaginary unit, k3 is the phase constant, d3 is the thickness of XLPE when there is no defect, and d2 is the thickness of the defect;
[0018] The equivalent wave impedance and equivalent reflection coefficient at the second interface are:
[0019]
[0020]
[0021] Wherein, η3′ is the equivalent wave impedance at the second interface, η3 is the wave impedance of XLPE, η2 is the wave impedance of air, and R2 is the equivalent reflection coefficient at the second interface;
[0022] The equivalent reflection coefficient of the second interface to the first interface is:
[0023]
[0024] Wherein, R2′ is the equivalent reflection coefficient of the second interface to the first interface, and k2 is the phase constant;
[0025] The equivalent wave impedance and equivalent reflection coefficient at the first interface are:
[0026]
[0027] Wherein, η2′ is the equivalent wave impedance at the second interface, η1 is the wave impedance of silicone rubber, and R1 is the equivalent reflection coefficient at the first interface;
[0028] The equivalent reflection coefficient of the first interface to the interface between the rectangular waveguide and the cable terminal is:
[0029]
[0030] Wherein, R1′ is the equivalent reflection coefficient of the first interface to the interface between the rectangular waveguide and the cable terminal, k1 is the phase constant, and d1 is the thickness of the silicone rubber;
[0031] The equivalent wave impedance and equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal are:
[0032]
[0033] Among them, η1′ is the equivalent wave impedance at the interface between the rectangular waveguide and the cable terminal, R is the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal, η TE Represents the wave impedance of the rectangular waveguide.
[0034] Optionally, the cable terminal defect types include air gap defects, mixing of conductive impurities and ingress of moisture.
[0035] Optionally, the cable terminal defect type is determined based on a value range of an equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal, specifically including:
[0036] Calculate the amplitude of the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal;
[0037] When the amplitude is within the first value range, the cable terminal defect type is moisture ingress;
[0038] When the amplitude is within the second value range, the cable terminal has no defects;
[0039] When the amplitude is within the third value range, the cable terminal defect type is an air gap defect;
[0040] When the amplitude is within the fourth value range, the cable terminal defect type is the mixing of conductive impurities;
[0041] The maximum value of the first value range is smaller than the minimum value of the second value range, the maximum value of the second value range is smaller than the minimum value of the third value range, and the maximum value of the third value range is smaller than the minimum value of the fourth value range.
[0042] In a second aspect, the present application provides a cable terminal defect detection device based on microwave reflection, wherein the cable terminal defect detection device based on microwave reflection applies any of the above-mentioned cable terminal defect detection methods based on microwave reflection, and the cable terminal defect detection device based on microwave reflection includes:
[0043] A microwave reflection multilayer dielectric model construction module is used to construct a microwave reflection multilayer dielectric model based on the multilayer structure of the cable terminal;
[0044] An equivalent reflection coefficient calculation model construction module is used to construct an equivalent reflection coefficient calculation model at the interface between a rectangular waveguide and a cable terminal based on a microwave reflection multilayer dielectric model; the rectangular waveguide is used to transmit microwaves into the cable terminal, and the microwaves are transmitted inside the cable terminal and reflected at each interface;
[0045] A calculation module, configured to calculate the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal according to the equivalent reflection coefficient calculation model;
[0046] The defect type determination module is used to determine the cable terminal defect type according to the value range of the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal.
[0047] In a third aspect, the present application provides a computer device comprising: 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 any one of the above-described methods for detecting cable terminal defects based on microwave reflection.
[0048] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any one of the above-mentioned methods for detecting cable terminal defects based on microwave reflection.
[0049] In a fifth aspect, the present application provides a computer program product, comprising a computer program, which, when executed by a processor, implements the steps of any one of the above-mentioned methods for detecting cable terminal defects based on microwave reflection.
[0050] According to the specific embodiments provided in this application, this application discloses the following technical effects:
[0051] The present application provides a method, apparatus, equipment, medium and product for detecting cable terminal defects based on microwave reflection. Since microwave reflection detection is a non-contact, non-destructive and highly sensitive detection technology, and when there are defects inside the cable terminal and the defect types are different, the reflection coefficient has a large difference. Therefore, by calculating the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal, the cable terminal defect type is determined according to the value range of the equivalent reflection coefficient, which can achieve fast, accurate and non-destructive detection of cable terminal defects. BRIEF DESCRIPTION OF THE DRAWINGS
[0052] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0053] Figure 1 A schematic flow chart of a cable terminal defect detection method based on microwave reflection provided in one embodiment of the present application;
[0054] Figure 2 A schematic diagram of a microwave-reflecting multilayer dielectric model provided in one embodiment of the present application;
[0055] Figure 3 A schematic diagram of the functional modules of a cable terminal defect detection device based on microwave reflection provided in one embodiment of the present application;
[0056] Figure 4 A schematic diagram of the structure of a computer device provided in one embodiment of the present application. DETAILED DESCRIPTION
[0057] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.
[0058] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.
[0059] In an exemplary embodiment, the present application provides a method for detecting cable terminal defects based on microwave reflection, such as Figure 1 As shown, the cable terminal defect detection method based on microwave reflection includes steps 101 to 104.
[0060] Step 101: Construct a microwave reflection multilayer dielectric model based on the multilayer structure of the cable terminal.
[0061] Step 102: Based on the microwave reflection multilayer medium model, an equivalent reflection coefficient calculation model at the interface between the rectangular waveguide and the cable terminal is constructed; the rectangular waveguide is used to transmit microwaves into the cable terminal, and the microwaves are transmitted inside the cable terminal and reflected at each interface.
[0062] Step 103: Calculate the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal according to the equivalent reflection coefficient calculation model.
[0063] Step 104: Determine the cable terminal defect type based on the value range of the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal.
[0064] The microwave nondestructive testing used in this application does not require coupling the test probe to the sample being tested. Microwaves can penetrate non-metallic materials, and any tiny defects in the material will cause changes in the material's dielectric properties. Furthermore, microwaves are non-ionizing and do not produce dangerous radiation, ensuring the safety of testers. This microwave nondestructive testing method can be applied to factory inspections of cable accessories, allowing personnel to promptly identify problems and ensure the stable operation of cable lines, thus having significant practical engineering significance.
[0065] The microwave wavelength used in this application is much smaller than the radial curvature radius of the cable terminal cross-section. To facilitate theoretical analysis, the complex multi-layer structure of the cable terminal is simplified into a multi-layer uniform medium in a flat plate shape, and the propagation process of microwaves in the multi-layer medium of the cable terminal is analyzed.
[0066] In an exemplary embodiment, the microwave reflection multilayer dielectric model is a four-layer dielectric structure, which is silicone rubber, defects, XLPE and metal arranged in sequence; microwaves are incident vertically from the silicone rubber surface and reflected in sequence at the third interface (interface 3), the second interface (interface 2) and the first interface (interface 1); the first interface is the interface between the silicone rubber and the defect, the second interface is the interface between the defect and the XLPE, and the third interface is the interface between the XLPE and the metal.
[0067] The microwave incident vertically from the silicone rubber surface is refracted and reflected at the interface of the multi-layer dielectric inside the cable terminal. The microwave propagation diagram is shown in the figure below. Figure 2 As shown, ε1, ε2, and ε3 are the relative dielectric constants of silicone rubber, air, and XLPE, respectively; μ1, μ2, and μ3 are the relative magnetic permeabilities of silicone rubber, air, and XLPE, respectively, and are all equal to 1. are the electric and magnetic field intensities of the incident wave at the interface i, E i- 、H i - are the electric and magnetic field intensities of the reflected wave at interface i, respectively, and i takes the value of 1, 2 or 3.
[0068] In an exemplary embodiment, based on a microwave reflection multilayer dielectric model, an equivalent reflection coefficient calculation model at the interface between a rectangular waveguide and a cable terminal is constructed, specifically including:
[0069] According to the equivalent wave impedance at each interface in the microwave reflection multilayer dielectric model, an equivalent reflection coefficient calculation model at the interface between the rectangular waveguide and the cable terminal is obtained; each interface includes the first interface, the second interface and the third interface.
[0070] This application calculates the equivalent wave impedance at each interface and combines it with the rectangular waveguide to obtain the final equivalent reflection coefficient calculation model.
[0071] In an exemplary embodiment, based on the equivalent wave impedance at each interface in the microwave reflection multilayer dielectric model, an equivalent reflection coefficient calculation model at the interface between the rectangular waveguide and the cable terminal is obtained, specifically including:
[0072] Since microwaves are totally reflected when encountering metal, the reflection coefficient at the third interface is R3 = -1. The equivalent reflection coefficient of the third interface to the second interface is:
[0073]
[0074] Wherein, R3′ is the equivalent reflection coefficient of the third interface to the second interface, R3 is the reflection coefficient of the third interface, j is the imaginary unit, k3 is the phase constant, d3 represents the thickness of XLPE when there is no defect, and d2 represents the thickness of the defect.
[0075] The equivalent wave impedance and equivalent reflection coefficient at the second interface are:
[0076]
[0077] Wherein, η3′ is the equivalent wave impedance at the second interface, η3 is the wave impedance of XLPE, η2 is the wave impedance of air, and R2 is the equivalent reflection coefficient at the second interface.
[0078] The equivalent reflection coefficient of the second interface to the first interface is:
[0079]
[0080] Wherein, R2′ is the equivalent reflection coefficient of the second interface to the first interface, and k2 is the phase constant.
[0081] The equivalent wave impedance and equivalent reflection coefficient at the first interface are:
[0082]
[0083]
[0084] Wherein, η2′ is the equivalent wave impedance at the second interface, η1 is the wave impedance of the silicone rubber, and R1 is the equivalent reflection coefficient at the first interface.
[0085] Considering the rectangular waveguide and the cable terminal as two transmission lines, the equivalent reflection coefficient of the first interface to the interface between the rectangular waveguide and the cable terminal is:
[0086]
[0087] Wherein, R1′ is the equivalent reflection coefficient of the first interface to the interface between the rectangular waveguide and the cable terminal, k1 is the phase constant, and d1 is the thickness of the silicone rubber.
[0088] Combined with the wave impedance of the rectangular waveguide, the equivalent wave impedance and equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal are calculated as follows:
[0089]
[0090] Among them, η1′ is the equivalent wave impedance at the interface between the rectangular waveguide and the cable terminal, R is the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal, η TE Represents the wave impedance of the rectangular waveguide.
[0091] Formula (9) is the calculation model of the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal. It is used to calculate the equivalent reflection coefficient R at the interface between the rectangular waveguide and the cable terminal. The result can be used to determine the defect type.
[0092] In an exemplary embodiment, the formula for calculating the magnitude of the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal is:
[0093] Where |R| is the amplitude of the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal, Re(R) is the real part of R, and Im(R) is the imaginary part of R.
[0094] From formula (9), we can see that when η1′=η TE When η1′≠η TEWhen , the reflection coefficient at the rectangular waveguide-cable terminal interface is not zero, and a reflected wave exists at the interface. The microwave reflection coefficient calculation model within the cable terminal shows that the reflection coefficient is related to the microwave wavelength used, the relative dielectric constant and thickness of each dielectric layer, the size of the rectangular waveguide's internal cross-section, and the detection distance.
[0095] Substituting the actual parameters into formula (9), the corresponding reflection coefficient can be obtained. According to the corresponding threshold value of the obtained reflection coefficient, the final internal defect type of the cable terminal can be obtained.
[0096] In an exemplary embodiment, the cable terminal defect types include air gap defects, mixing of conductive impurities, and ingress of moisture.
[0097] Substituting the actual relative permittivity and thickness data for the multilayer dielectric in cable terminals, as reported in Table 1, into the theoretically derived microwave reflection coefficient calculation model for cable terminals, Table 2 shows the calculated reflection coefficients for different defect types. The theoretical model shows that compared to defect-free locations, the reflection coefficient of defects containing air gaps between the silicone rubber and XLPE in cable terminals increases, differing by approximately 27.1%. When the defect contains conductive impurities, the reflection coefficient reaches its maximum, differing significantly from that of defect-free locations by approximately 74.3%. When moisture enters the defect, the reflection coefficient decreases, differing by approximately -40.1%. In summary, the reflection coefficient varies significantly depending on the presence and type of defects within the cable terminal. Therefore, changes in the reflection coefficient can be used to identify defects within the cable terminal.
[0098] Table 1 Parameters of each layer of dielectric at the cable terminal
[0099]
[0100] Table 2 Calculation results of reflection coefficient R for different types of defects
[0101]
[0102]
[0103] In an exemplary embodiment, the cable terminal defect type is determined based on a value range of an equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal, specifically including:
[0104] Calculate the magnitude of the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal.
[0105] When the amplitude is within the first value range, the cable terminal defect type is moisture ingress.
[0106] When the amplitude is within the second value range, the cable terminal has no defects.
[0107] When the amplitude is within the third value range, the cable terminal defect type is an air gap defect.
[0108] When the amplitude is within the fourth value range, the cable terminal defect type is the mixing of conductive impurities.
[0109] The maximum value of the first value range is smaller than the minimum value of the second value range, the maximum value of the second value range is smaller than the minimum value of the third value range, and the maximum value of the third value range is smaller than the minimum value of the fourth value range.
[0110] The cable terminal defect detection method based on microwave reflection in this application is a non-contact, non-destructive, and highly sensitive detection technology with the advantages of penetrating non-conductive materials, real-time and rapid detection, and adaptability to complex shapes and environments. It can identify different defects inside the cable terminal.
[0111] Based on the same inventive concept, embodiments of the present application also provide a microwave reflection-based cable terminal defect detection device for implementing the aforementioned microwave reflection-based cable terminal defect detection method. The solution provided by this device is similar to the solution described in the aforementioned method. Therefore, the specific limitations of one or more of the following embodiments of the microwave reflection-based cable terminal defect detection device can be found in the above-described limitations of the microwave reflection-based cable terminal defect detection method and are not further elaborated here.
[0112] In an exemplary embodiment, Figure 3 As shown, a cable terminal defect detection device based on microwave reflection is provided, comprising:
[0113] The microwave reflection multilayer dielectric model construction module is used to construct a microwave reflection multilayer dielectric model according to the multilayer structure of the cable terminal.
[0114] An equivalent reflection coefficient calculation model construction module is used to construct an equivalent reflection coefficient calculation model at the interface between a rectangular waveguide and a cable terminal based on a microwave reflection multilayer medium model; the rectangular waveguide is used to transmit microwaves into the interior of the cable terminal, and the microwaves are transmitted inside the cable terminal and reflected at each interface.
[0115] A calculation module is used to calculate the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal according to the equivalent reflection coefficient calculation model.
[0116] The defect type determination module is used to determine the cable terminal defect type according to the value range of the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal.
[0117] In an exemplary embodiment, a computer device is provided. The computer device may be a server or a terminal. The internal structure diagram thereof may be as follows: Figure 4 As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, abbreviated as I / O) and a communication interface. The processor, memory and input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and computer program in the non-volatile storage medium. The database of the computer device is used to store cable terminal defect detection data based on microwave reflection. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a cable terminal defect detection method based on microwave reflection is implemented.
[0118] Those skilled in the art will understand that Figure 4 The structure shown in the figure is merely a block diagram of a portion of the structure related to the solution of the present application and does not constitute a limitation on the computer device to which the solution of the present application is applied. A specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement. In an exemplary embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program, and the processor implements the steps of the above-mentioned method embodiments when executing the computer program.
[0119] In an exemplary embodiment, a computer-readable storage medium is provided, storing a computer program. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented.
[0120] In an exemplary embodiment, a computer program product is provided, including a computer program. When the computer program is executed by a processor, the steps in the above method embodiments are implemented.
[0121] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.
[0122] Those skilled in the art will understand that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, database or other media used in the embodiments provided in this application may include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory may include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM may be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).
[0123] The databases involved in the various embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, distributed databases based on blockchains. The processors involved in the various embodiments provided herein may be, but are not limited to, general-purpose processors, central processing units, graphics processing units, digital signal processors, data processing logic of programmable logic devices, and the like.
[0124] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0125] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.
Claims
1. A cable terminal defect detection method based on microwave reflection, characterized in that: The cable terminal defect detection method based on microwave reflection includes: Construct a microwave reflection multilayer dielectric model based on the multilayer structure of the cable terminal; Based on a microwave reflection multilayer dielectric model, an equivalent reflection coefficient calculation model is constructed at the interface between a rectangular waveguide and a cable terminal. The rectangular waveguide is used to transmit microwaves into the cable terminal. The microwaves propagate inside the cable terminal and are reflected at each interface. Calculate the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal according to the equivalent reflection coefficient calculation model; The defect type of the cable terminal is determined according to the value range of the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal.
2. The cable terminal defect detection method based on microwave reflection according to claim 1 is characterized in that: The microwave reflection multilayer dielectric model is a four-layer dielectric structure, which is composed of silicone rubber, defects, XLPE and metal arranged in sequence. Microwaves are incident vertically from the silicone rubber surface and are reflected at the third interface, the second interface and the first interface in sequence. The first interface is the interface between the silicone rubber and the defect, the second interface is the interface between the defect and the XLPE, and the third interface is the interface between the XLPE and the metal.
3. The cable terminal defect detection method based on microwave reflection according to claim 2, characterized in that: Based on the microwave reflection multilayer dielectric model, an equivalent reflection coefficient calculation model at the interface between the rectangular waveguide and the cable terminal is constructed, specifically including: According to the equivalent wave impedance at each interface in the microwave reflection multilayer dielectric model, an equivalent reflection coefficient calculation model at the interface between the rectangular waveguide and the cable terminal is obtained; each interface includes the first interface, the second interface and the third interface.
4. The cable terminal defect detection method based on microwave reflection according to claim 3 is characterized in that: According to the equivalent wave impedance at each interface in the microwave reflection multilayer dielectric model, an equivalent reflection coefficient calculation model at the interface between the rectangular waveguide and the cable terminal is obtained, which specifically includes: The equivalent reflection coefficient of the third interface to the second interface is: Where R3′ is the equivalent reflection coefficient of the third interface to the second interface, R3 is the reflection coefficient of the third interface, j is the imaginary unit, k3 is the phase constant, d3 is the thickness of XLPE when there is no defect, and d2 is the thickness of the defect; The equivalent wave impedance and equivalent reflection coefficient at the second interface are: Wherein, η3′ is the equivalent wave impedance at the second interface, η3 is the wave impedance of XLPE, η2 is the wave impedance of air, and R2 is the equivalent reflection coefficient at the second interface; The equivalent reflection coefficient of the second interface to the first interface is: Wherein, R2′ is the equivalent reflection coefficient of the second interface to the first interface, and k2 is the phase constant; The equivalent wave impedance and equivalent reflection coefficient at the first interface are: Wherein, η2′ is the equivalent wave impedance at the second interface, η1 is the wave impedance of silicone rubber, and R1 is the equivalent reflection coefficient at the first interface; The equivalent reflection coefficient of the first interface to the interface between the rectangular waveguide and the cable terminal is: Wherein, R1′ is the equivalent reflection coefficient of the first interface to the interface between the rectangular waveguide and the cable terminal, k1 is the phase constant, and d1 is the thickness of the silicone rubber; The equivalent wave impedance and equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal are: Among them, η1′ is the equivalent wave impedance at the interface between the rectangular waveguide and the cable terminal, R is the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal, η TE Represents the wave impedance of the rectangular waveguide.
5. The cable terminal defect detection method based on microwave reflection according to claim 1, characterized in that: The cable terminal defect types include air gap defects, mixing of conductive impurities and ingress of moisture.
6. The cable terminal defect detection method based on microwave reflection according to claim 5, characterized in that: The cable terminal defect type is determined based on the range of the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal, including: Calculate the amplitude of the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal; When the amplitude is within the first value range, the cable terminal defect type is moisture ingress; When the amplitude is within the second value range, the cable terminal has no defects; When the amplitude is within the third value range, the cable terminal defect type is an air gap defect; When the amplitude is within the fourth value range, the cable terminal defect type is the mixing of conductive impurities; The maximum value of the first value range is smaller than the minimum value of the second value range, the maximum value of the second value range is smaller than the minimum value of the third value range, and the maximum value of the third value range is smaller than the minimum value of the fourth value range.
7. A cable terminal defect detection device based on microwave reflection, characterized in that: The cable terminal defect detection device based on microwave reflection applies the cable terminal defect detection method based on microwave reflection according to any one of claims 1 to 6, and the cable terminal defect detection device based on microwave reflection includes: A microwave reflection multilayer dielectric model construction module is used to construct a microwave reflection multilayer dielectric model based on the multilayer structure of the cable terminal; An equivalent reflection coefficient calculation model construction module is used to construct an equivalent reflection coefficient calculation model at the interface between a rectangular waveguide and a cable terminal based on a microwave reflection multilayer dielectric model; the rectangular waveguide is used to transmit microwaves into the cable terminal, and the microwaves are transmitted inside the cable terminal and reflected at each interface; A calculation module, configured to calculate the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal according to the equivalent reflection coefficient calculation model; The defect type determination module is used to determine the cable terminal defect type according to the value range of the equivalent reflection coefficient at the interface between the rectangular waveguide and the cable terminal.
8. A computer device comprising: 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 cable terminal defect detection method based on microwave reflection according to any one of claims 1 to 6.
9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the cable terminal defect detection method based on microwave reflection according to any one of claims 1 to 6 is implemented.
10. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the cable terminal defect detection method based on microwave reflection according to any one of claims 1 to 6 is implemented.