Electromagnetic wave-based cable accessory assembly quality inspection method and related equipment

Abstract

This application discloses a method and related equipment for inspecting the assembly quality of cable accessories based on electromagnetic waves, relating to the field of cable quality inspection technology. Through electromagnetic wave reflection testing, multiple test points at different parts of the cable accessory can be comprehensively inspected, and the internal structure of the cable accessory can be deeply inspected to accurately identify assembly defects. The method obtains the intensity of the reflected electromagnetic wave signal, constructs an electromagnetic wave reflection signal curve, and calculates the electromagnetic wave signal reflectivity. Based on the electromagnetic wave signal reflectivity and the electromagnetic wave reflection signal curve, the assembly quality inspection results for each part are obtained, accurately determining whether the assembly is qualified and unaffected by subjective factors. This achieves comprehensive and accurate inspection of the assembly quality of cable accessories, effectively improving inspection efficiency and accuracy, reducing the risk of power failure, ensuring the safe and stable operation of the cable system, and reducing economic losses and safety hazards.

Description

Technical Field

[0001] This invention relates to the field of cable quality testing technology, and in particular to a method and related equipment for testing the assembly quality of cable accessories based on electromagnetic waves. Background Technology

[0002] During the assembly of cable accessories, the assembly quality directly affects the operational stability and safety of the cable system. Traditional inspection methods mostly rely on manual visual inspection or simple mechanical measurement, which have significant limitations. Manual visual inspection is easily affected by subjective factors and is difficult to detect minute internal defects; while mechanical measurement can obtain some data, it cannot comprehensively reflect the assembly status of various parts of the cable accessory. In particular, different parts of the cable accessory have complex structures, and there may be hidden defects such as air gaps and misalignments, which are difficult to detect accurately using traditional methods. If these defects are not detected in time, they may lead to problems such as partial discharge and insulation failure in the cable accessory during operation, which may then cause power failures, resulting in significant economic losses and safety hazards. Summary of the Invention

[0003] In view of this, the present invention provides a method and related equipment for inspecting the assembly quality of cable accessories based on electromagnetic waves.

[0004] The specific technical solution of the first embodiment of the present invention is as follows: a method for inspecting the assembly quality of cable accessories based on electromagnetic waves, the method comprising: performing electromagnetic wave reflection tests on different test points at different parts of the cable accessory, obtaining the electromagnetic wave incident signal intensity and electromagnetic wave reflected signal intensity at different test points of each part during the electromagnetic wave reflection test; constructing an electromagnetic wave reflection signal curve for each part based on the electromagnetic wave reflection signal intensity of each part; obtaining the electromagnetic wave signal reflectivity of each test point of each part based on the electromagnetic wave incident signal intensity and the electromagnetic wave reflected signal intensity; obtaining the assembly quality inspection result for each part based on the electromagnetic wave signal reflectivity and the electromagnetic wave reflection signal curve; the assembly quality inspection result includes assembly qualified and assembly unqualified.

[0005] Preferably, obtaining the assembly quality inspection result for each part based on the electromagnetic wave signal reflectivity and the electromagnetic wave reflection signal curve includes: obtaining the reflectivity change at each test point of each part based on the electromagnetic wave signal reflectivity and a preset standard reflectivity; the standard reflectivity is the electromagnetic wave signal reflectivity of different parts of the assembled qualified cable accessory; obtaining the peak time of the peak electromagnetic wave reflection signal intensity of each part from the electromagnetic wave reflection signal curve; and obtaining the assembly quality inspection result for each part based on the reflectivity change and the peak time.

[0006] Preferably, obtaining the assembly quality inspection result of each part based on the reflectivity change and the peak time includes: obtaining the peak time difference of each part based on the peak time and the preset standard time; the preset standard time is the peak time when the peak electromagnetic wave reflection signal intensity of different parts of the assembled qualified cable accessory appears; and obtaining the assembly quality inspection result of each part based on the reflectivity change and the peak time difference.

[0007] Preferably, obtaining the assembly quality inspection result for each part based on the reflectivity change and the peak time difference includes: if the first reflectivity change of the stress cone part and the second reflectivity change of the inner electrode part of the cable accessory are both less than or equal to a first preset threshold, and the first peak time difference of the stress cone part and the second peak time difference of the inner electrode part are both less than or equal to a second preset threshold and greater than or equal to a third preset threshold, then the assembly quality inspection result of the cable accessory is qualified; the third preset threshold is less than the second preset threshold; if the first reflectivity change is greater than the first preset threshold or the second reflectivity change is greater than the first preset threshold, and the first peak time difference is greater than the second preset threshold, then the assembly quality inspection result of the stress cone part is unqualified; if the first reflectivity change is greater than the first preset threshold or the second reflectivity change is greater than the first preset threshold, and the second peak time difference is less than the third preset threshold, then the assembly quality inspection result of the inner electrode part is unqualified.

[0008] Preferably, before obtaining the electromagnetic wave signal reflectivity of each test point at each location based on the electromagnetic wave incident signal intensity and the electromagnetic wave reflected signal intensity, the method further includes: performing a frequency domain to time domain signal transformation on the electromagnetic wave incident signal intensity and the electromagnetic wave reflected signal intensity to obtain the electromagnetic wave incident signal intensity and the electromagnetic wave reflected signal intensity in the time domain; then, obtaining the electromagnetic wave signal reflectivity of each test point at each location based on the electromagnetic wave incident signal intensity and the electromagnetic wave reflected signal intensity includes: obtaining the electromagnetic wave signal reflectivity of each test point at each location based on the electromagnetic wave incident signal intensity and the electromagnetic wave reflected signal intensity in the time domain.

[0009] Preferably, the first preset threshold, the second preset threshold, and the third preset threshold are obtained using the following formula:

[0010] ,

[0011] in, δ The first preset threshold, The second preset threshold, The third preset threshold, The peak value of the incident electromagnetic wave signal intensity. The start time of the time window set for the electromagnetic wave propagation time during electromagnetic wave reflection testing. The end time of the time window set for the electromagnetic wave propagation time during electromagnetic wave reflection testing. The number of sampling data points set during time-domain transformation.

[0012] Preferably, the electromagnetic wave signal reflectivity is obtained using the following formula:

[0013]

[0014] in, The reflectivity of the electromagnetic wave signal is... The intensity of the incident electromagnetic wave signal. The intensity of the reflected electromagnetic wave signal is denoted as .

[0015] The specific technical solution of the second embodiment of the present invention is as follows: a cable accessory assembly quality inspection system based on electromagnetic waves, the system comprising: a signal strength acquisition module, a reflection signal curve acquisition module, a reflectivity acquisition module, and a detection module; the signal strength acquisition module is used to perform electromagnetic wave reflection tests on different test points at different parts of the cable accessory, and acquire the electromagnetic wave incident signal strength and electromagnetic wave reflected signal strength at different test points of each part during the electromagnetic wave reflection test; the reflection signal curve acquisition module is used to construct an electromagnetic wave reflection signal curve for each part based on the electromagnetic wave reflection signal strength of each part; the reflectivity acquisition module is used to obtain the electromagnetic wave signal reflectivity of each test point of each part based on the electromagnetic wave incident signal strength and the electromagnetic wave reflected signal strength; the detection module is used to obtain the assembly quality inspection result of each part based on the electromagnetic wave signal reflectivity and the electromagnetic wave reflection signal curve; the assembly quality inspection result includes assembly qualified and assembly unqualified.

[0016] The specific technical solution of the third embodiment of the present invention is as follows: a cable accessory assembly quality inspection device based on electromagnetic waves, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the method as described in any one of the first embodiments of this application.

[0017] The specific technical solution of the fourth embodiment of the present invention is as follows: a computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor performs the steps of the method as described in any one of the first embodiments of this application.

[0018] Implementing the embodiments of the present invention will have the following beneficial effects:

[0019] This invention utilizes electromagnetic wave reflection testing to comprehensively inspect multiple test points at different locations of cable accessories. It can also deeply examine the internal structure of cable accessories, accurately identify assembly defects, obtain the intensity of reflected electromagnetic wave signals, construct electromagnetic wave reflection signal curves, and calculate electromagnetic wave reflectivity. Based on the electromagnetic wave reflectivity and electromagnetic wave reflection signal curves, the assembly quality inspection results for each location are obtained, accurately determining whether the assembly is qualified. This is unaffected by subjective factors, enabling comprehensive and accurate inspection of cable accessory assembly quality. This effectively improves inspection efficiency and accuracy, reduces the risk of power failures, ensures the safe and stable operation of cable systems, and minimizes economic losses and safety hazards. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, 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 this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A flowchart illustrating the steps of an electromagnetic wave-based method for inspecting the assembly quality of cable accessories.

[0022] Figure 2 A schematic diagram of the normal installation structure and electromagnetic wave detection of cable intermediate joint accessories;

[0023] Figure 3 This is a schematic diagram of the electromagnetic wave detection results at the stress cone location.

[0024] Figure 4 A schematic diagram of the electromagnetic wave detection results at the internal electrode area;

[0025] Figure 5 This is a schematic diagram showing the detection results of the peak time of electromagnetic wave reflection at the stress cone.

[0026] Figure 6 A schematic diagram showing the detection results of the peak time of electromagnetic wave reflection at the inner electrode.

[0027] Figure 7 A schematic diagram showing the change in reflectivity at different parts of a cable accessory;

[0028] Figure 8 A schematic diagram showing the peak reflection time difference at different parts of a cable accessory;

[0029] Figure 9 A schematic diagram of a cable accessory assembly quality inspection system based on electromagnetic waves;

[0030] Among them, 201 is the signal strength acquisition module; 202 is the reflection signal curve acquisition module; 203 is the reflectivity acquisition module; and 204 is the detection module. Detailed Implementation

[0031] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0032] The terms "first," "second," etc., used in the specification, claims, and drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or modules is not limited to the listed steps or modules, but may optionally include steps or modules not listed, or may optionally include other steps or modules inherent to such processes, methods, products, or apparatus.

[0033] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0034] Please see Figure 1 This is a flowchart illustrating the steps of a cable accessory assembly quality inspection method based on electromagnetic waves in the first embodiment of this application. This method ensures the safe and stable operation of the cable system while reducing economic losses and safety hazards. The method includes:

[0035] Step 101: Perform electromagnetic wave reflection tests on different test points at different parts of the cable accessories, and obtain the electromagnetic wave incident signal intensity and electromagnetic wave reflected signal intensity at different test points of each part during the electromagnetic wave reflection test.

[0036] Step 102: Based on the electromagnetic wave reflection signal intensity of each part, construct the electromagnetic wave reflection signal curve for each part;

[0037] Step 103: Based on the electromagnetic wave incident signal intensity and the electromagnetic wave reflected signal intensity, obtain the electromagnetic wave signal reflectivity of each test point at each location;

[0038] Step 104: Obtain the assembly quality inspection results for each part based on the electromagnetic wave signal reflectivity and the electromagnetic wave reflection signal curve; the assembly quality inspection results include qualified assembly and unqualified assembly.

[0039] Specifically, for different parts of the cable accessories, such as stress cones and internal electrodes, multiple representative test points are selected. A professional electromagnetic wave reflection tester is used to perform electromagnetic wave reflection tests at each test point. During the test, the intensity of the incident electromagnetic wave signal and the intensity of the reflected electromagnetic wave signal are recorded at each test point. Based on the obtained electromagnetic wave reflection signal intensity data for each part, an electromagnetic wave reflection signal curve is constructed with the test point as the x-axis and the reflection signal intensity as the y-axis. This curve can intuitively reflect the reflection of electromagnetic waves at different test points. The electromagnetic wave signal reflectivity is calculated for each test point of each part based on the incident and reflected electromagnetic wave signal intensities. Combining the electromagnetic wave signal reflectivity and the electromagnetic wave reflection signal curve, the assembly quality of each part is comprehensively evaluated. If both the reflectivity and the reflection signal curve are within the normal range, the assembly of that part is considered qualified; if there is an abnormal increase in reflectivity or distortion of the reflection signal curve, the assembly of that part is considered unqualified.

[0040] The method in this embodiment, through electromagnetic wave reflection testing, can comprehensively inspect multiple test points at different parts of cable accessories, and can deeply inspect the internal structure of cable accessories, accurately detect assembly defects, obtain the intensity of electromagnetic wave reflection signals, construct electromagnetic wave reflection signal curves, and calculate electromagnetic wave signal reflectivity. Based on the electromagnetic wave signal reflectivity and electromagnetic wave reflection signal curves, the assembly quality inspection results of each part can be obtained, accurately determining whether the assembly is qualified, and is not affected by subjective factors. This achieves comprehensive and accurate inspection of the assembly quality of cable accessories, effectively improving inspection efficiency and accuracy, reducing the risk of power failure, ensuring the safe and stable operation of the cable system, and reducing economic losses and safety hazards.

[0041] In a specific embodiment, obtaining the assembly quality inspection result of each part based on the electromagnetic wave signal reflectivity and the electromagnetic wave reflection signal curve includes: obtaining the reflectivity change of each test point of each part based on the electromagnetic wave signal reflectivity and a preset standard reflectivity; the standard reflectivity is the electromagnetic wave signal reflectivity of different parts of the assembled qualified cable accessory; obtaining the peak time of the peak occurrence of the electromagnetic wave reflection signal intensity of each part in the electromagnetic wave reflection signal curve; and obtaining the assembly quality inspection result of each part based on the reflectivity change and the peak time.

[0042] Specifically, based on the comparative analysis of the electromagnetic wave signal reflectivity and the preset standard reflectivity, the reflectivity change amount of each test point of each part is calculated. Among them, the preset standard reflectivity is obtained through the statistics of the electromagnetic wave signal reflectivity data of different parts of a large number of qualified cable accessories, and is used as the evaluation benchmark. By calculating the difference between the actual reflectivity and the standard reflectivity, the abnormal degree of the reflectivity of each test point can be quantified, providing data support for subsequent analysis. In the constructed electromagnetic wave reflection signal curve, the peak time corresponding to the peak value of the electromagnetic wave reflection signal intensity of each part is extracted. The peak time reflects the reflection characteristics of the electromagnetic wave during the propagation process in a specific part. Different assembly states will cause differences in the peak time, so it can be used as an important parameter for evaluating the assembly quality.

[0043] Based on the two indicators of the reflectivity change amount and the peak time, the assembly quality of each part is judged. If the reflectivity change amount is within a reasonable range and the peak time meets the expectation, it is determined that the assembly of this part is qualified; if the reflectivity change amount exceeds the threshold or the peak time is abnormal, it is determined that the assembly is unqualified. Through this scheme, the assembly quality of each part of the cable accessory can be evaluated more comprehensively and accurately, potential problems can be discovered in time, and the reliable operation of the cable accessory can be ensured.

[0044] In a specific embodiment, obtaining the assembly quality detection result of each part according to the reflectivity change amount and the peak time includes: obtaining the peak time difference of each part according to the peak time and the preset standard time; the preset standard time is the peak time when the peak value of the electromagnetic wave reflection signal intensity of different parts of the qualified cable accessory appears; obtaining the assembly quality detection result of each part according to the reflectivity change amount and the peak time difference.

[0045] Specifically, based on the peak time of each part extracted from the electromagnetic wave reflection signal curve, the peak time difference is calculated in combination with the preset standard time. The preset standard time is obtained through a large number of tests on qualified cable accessories and statistics of the standard time range when the peak value of the electromagnetic wave reflection signal intensity of different parts appears. Comparing the actually measured peak time with the preset standard time, the peak time difference of each part is obtained. This difference can reflect the abnormal changes in the propagation path or speed of the electromagnetic wave inside the component and is closely related to the assembly quality. Based on the two indicators of the reflectivity change amount and the peak time difference, the assembly quality of each part is comprehensively judged. Among them, the reflectivity change amount reflects the abnormal degree of the electromagnetic wave reflection intensity, and the peak time difference reflects the change in the propagation characteristics. The combination of the two can more comprehensively evaluate the assembly state.

[0046] Specifically, obtaining the assembly quality inspection result for each part based on the reflectivity change and the peak time difference includes: if the first reflectivity change of the stress cone part and the second reflectivity change of the inner electrode part of the cable accessory are both less than or equal to a first preset threshold, and the first peak time difference of the stress cone part and the second peak time difference of the inner electrode part are both less than or equal to a second preset threshold and greater than or equal to a third preset threshold, then the assembly quality inspection result of the cable accessory is qualified; the third preset threshold is less than the second preset threshold; if the first reflectivity change is greater than the first preset threshold or the second reflectivity change is greater than the first preset threshold, and the first peak time difference is greater than the second preset threshold, then the assembly quality inspection result of the stress cone part is unqualified; if the first reflectivity change is greater than the first preset threshold or the second reflectivity change is greater than the first preset threshold, and the second peak time difference is less than the third preset threshold, then the assembly quality inspection result of the inner electrode part is unqualified.

[0047] In a specific embodiment, the first preset threshold, the second preset threshold, and the third preset threshold are obtained using the following formula:

[0048] ,

[0049] in, δ The first preset threshold, The second preset threshold, The third preset threshold, The peak value of the incident electromagnetic wave signal intensity. The start time of the time window set for the electromagnetic wave propagation time during electromagnetic wave reflection testing. The end time of the time window set for the electromagnetic wave propagation time during electromagnetic wave reflection testing. The number of sampling data points set during time-domain transformation.

[0050] Specifically, when the change in the first reflectivity at the stress cone and the change in the second reflectivity at the inner electrode are both less than or equal to... δ And the first peak time and the second peak time are both within ( , If the change in reflectivity is within the specified range, the cable accessory is considered to be installed correctly; if either the change in the first reflectivity at the stress cone or the change in the second reflectivity at the inner electrode is greater than 1 / 3, the cable accessory is considered to be installed correctly. δ And the second peak time is less than If either the change in the first reflectivity at the stress cone or the change in the second reflectivity at the inner electrode is greater than 1, it is considered a misalignment of the inner electrode installation in the cable accessory. δAnd the first peak time is greater than If so, it is determined that the stress cone of the cable accessory is misaligned.

[0051] In a specific embodiment, the electromagnetic wave signal reflectivity is obtained using the following formula:

[0052]

[0053] in, The reflectivity of the electromagnetic wave signal is... The intensity of the incident electromagnetic wave signal. The intensity of the reflected electromagnetic wave signal is denoted as .

[0054] In a specific embodiment, before obtaining the electromagnetic wave signal reflectivity of each test point at each location based on the electromagnetic wave incident signal intensity and the electromagnetic wave reflected signal intensity, the method further includes: performing a frequency domain to time domain signal transformation on the electromagnetic wave incident signal intensity and the electromagnetic wave reflected signal intensity to obtain the electromagnetic wave incident signal intensity and the electromagnetic wave reflected signal intensity in the time domain; then, obtaining the electromagnetic wave signal reflectivity of each test point at each location based on the electromagnetic wave incident signal intensity and the electromagnetic wave reflected signal intensity in the time domain includes: obtaining the electromagnetic wave signal reflectivity of each test point at each location based on the electromagnetic wave incident signal intensity and the electromagnetic wave reflected signal intensity in the time domain.

[0055] Specifically, the obtained electromagnetic wave frequency domain signals x1 and x2 are transformed from the frequency domain to the time domain, and the start time of the time window is set according to the electromagnetic wave transmission time matched by the length of the electromagnetic wave transmission line. t 1 and end time t 2. For frequency domain signals x ( n Perform time-frequency domain transformation to obtain the corresponding time-domain signal. The transformation formula is as follows:

[0056]

[0057] in, y = AW -k For isoangular sampling points, k =0,1,..., M -1, M for y The number of data points in this embodiment M It is 250. The starting point position; The sampling increment is for the spiral. N for x ( n The number of data points in this embodiment N It is 600;A 0 is the starting radius, in this embodiment A 0 is equivalent to 1; θ 0 represents the initial phase. In this embodiment... θ 0 is 2π t 1 / 600, t 1 represents the start time of the time window; W 0 represents the elongation of the spiral, in this embodiment... W 0 is equivalent to 1; φ 0 represents the angular frequency difference between two adjacent test points. In this embodiment... φ 0 is 2π / 600.

[0058] Specifically, the complete technical solution of this embodiment is as follows:

[0059] Step 1. Prepare the intermediate joint accessories of the 10kV cable to be tested, and remove foreign objects, impurities, etc. that may affect the test results;

[0060] Step 2. Connect the equipment: Connect the power supply, electromagnetic wave signal source, electromagnetic wave transmission line, antenna probe, clamp, and software control device, ensuring a stable and reliable connection. Set the starting frequency to 12GHz and the ending frequency to 18GHz according to the electromagnetic wave frequency band matched to the antenna probe used; the electromagnetic wave signal output power should be 15dBm.

[0061] Step 3. The test mode is reflection mode. After selecting the electromagnetic wave transmission time matched with the length of the electromagnetic wave transmission line and performing free space calibration to remove background noise, the antenna probe is placed close to the surface of the cable accessory and electromagnetic wave signals are emitted to the cable accessory. The electromagnetic wave signals are reflected by the interface of the cable accessory surface, stress cone or inner electrode, outer semiconductive layer, and XLPE insulation layer, and then received by the antenna probe as electromagnetic wave frequency domain reflection signals of different intensities.

[0062] Step 4. Set up different assembly misalignment scenarios (normal installation, stress cone misalignment, and internal electrode misalignment) for the cable joint accessories, and perform electromagnetic wave reflection tests on these three scenarios. Set up test points on the surface of the accessory corresponding to the stress cone or internal electrode area of ​​the cable joint accessory to be tested. For example... Figure 2 As shown, in this embodiment, the surface test areas at the stress cone and inner electrode are divided into three parts, each with a different accessory structure. 24 points are tested at the stress cone (8 points per part); 30 points are tested at the inner electrode (10 points per part). This allows for relatively dense sampling of the test areas during antenna probe movement, achieving the most detailed possible structural information on the stress cone and inner electrode areas of the cable accessory. The test process ends when the set number of test points is reached. The electromagnetic wave frequency domain reflected signal intensity at different parts of the cable accessory is obtained, and the electromagnetic wave frequency domain incident signal intensity is recorded simultaneously.

[0063] Step 5. Process the obtained electromagnetic wave frequency domain signal. x Perform signal transformation from the frequency domain to the time domain, for frequency domain signals x ( n Perform time-frequency domain transformation to obtain the corresponding time-domain signal. X ( y ).

[0064] Step 6. Set the start time of the time window according to the electromagnetic wave transmission time matched by the length of the electromagnetic wave transmission line. t 1 is 26ns, termination time t 2 is 28 ns, recording the time-domain reflection signal at each acquisition point. X The time of peak occurrence t m And plot the peak time t m The curve showing how the number of test data collection points changes.

[0065] Step 7. Calculate the reflectivity λ of the obtained electromagnetic wave time-domain signal after reflection by the cable accessory. The calculation formula is as follows:

[0066]

[0067] in, X 1 represents the intensity of the incident electromagnetic wave signal. X 2 represents the intensity of the reflected electromagnetic wave signal; in this embodiment, the intensity of the incident electromagnetic wave signal is... X 1. After being set, the peak value remained basically unchanged under various test conditions. X 1max It remains at approximately -25dB.

[0068] Step 8. Plot reflectivity λ and peak time. t m The curves showing the variation with the number of sampling points are shown. The number of sampling points for both the reflectance curve and the peak time curve is normalized. The normalized Zi is shown in the following formula:

[0069] Zi = zi / B

[0070] Where i is the sampling point number, i=1,2,...,B, and B is the total number of sampling points for each test. In this embodiment, B is 24 for the stress cone test site and 30 for the inner electrode test site. The normalized electromagnetic wave time-domain reflectivity curve X is shown below. Figure 3 , Figure 4 As shown, the peak time after normalization t m Curves Figure 5 , Figure 6 As shown. According to Figure 2 As shown, when the stress cone is misaligned, the semiconductive layer extends to the third part, causing a change in the structure of the second and third parts near the stress cone position. Figure 3 It can be seen that the electromagnetic wave reflectivity of the second and third parts when the stress cone is misaligned differs significantly from that under normal installation. Figure 5 It can be seen that the peak value is delayed near the end of the stress cone (in parts 2 and 3 near the end of the stress cone), resulting in an increased peak time. When the inner electrode is misaligned, it fails to connect to the XLPE insulation layer, causing a change in the structure of part 5. Figure 4 It can be seen that the electromagnetic wave reflectivity in Part 5 differs significantly from the reflectivity under normal internal electrode installation conditions. Figure 6 It can be seen that the peak value in part 5 is ahead of the time, which reduces the peak time.

[0071] Step 9. Compare the reflectivity changes under normal installation conditions, and calculate the reflectivity change using the following formula. :

[0072]

[0073] in, The electromagnetic wave reflectivity under the current test conditions. This represents the electromagnetic wave reflectivity under normal installation conditions. Curves Figure 7 As shown.

[0074] Step 10. Compare the obtained peak time curve with the curve when the installation is correct, and calculate the time difference between the corresponding sampling points of the two curves. The calculation formula is as follows:

[0075]

[0076] in, This represents the peak time corresponding to a certain data collection point. The peak time of the corresponding sampling point is to ensure that the cable accessories are installed correctly. Curves Figure 8 As shown.

[0077] Combination Figure 7 , Figure 8 It can be seen that the change in reflectivity is related to the stress cone and inner electrode installation locations where misalignment did not occur in the cable accessory. ;

[0078] At the same time, the peak time difference satisfies ; The location where the stress cone is misaligned >2%, and >0.008ns; Misalignment of the internal electrode installation location >2%, and <-0.008ns.

[0079] The method in this application identifies and detects differences in electromagnetic wave reflection signals reflected by structural changes in the assembly misalignment defects of cable accessories, rather than based on the discharge signal characteristics of partial discharges already triggered by the defects during operation. Therefore, this method can promptly detect defects present after cable accessory assembly, identifying potential problems during the construction phase for timely correction and elimination.

[0080] The method in this application has the advantages of simple operation, fast detection speed, non-destructive nature, on-site application, online testing, and timely detection of defects that have not generated partial discharge. It fills the gap in the existing technology for electromagnetic wave time-domain reflection detection method specifically for cable accessory assembly misalignment, and can serve as a useful supplement to the cable accessory assembly quality assessment method.

[0081] In a specific embodiment, please refer to Figure 9 This is a schematic diagram of a cable accessory assembly quality inspection system based on electromagnetic waves according to a second embodiment of this application. The system includes: a signal strength acquisition module 201, a reflection signal curve acquisition module 202, a reflectivity acquisition module 203, and a detection module 204. The signal strength acquisition module 201 is used to perform electromagnetic wave reflection tests on different test points at different parts of the cable accessory, and acquire the electromagnetic wave incident signal intensity and electromagnetic wave reflected signal intensity at different test points of each part during the electromagnetic wave reflection test. The reflection signal curve acquisition module 202 is used to construct an electromagnetic wave reflection signal curve for each part based on the electromagnetic wave reflection signal intensity of each part. The reflectivity acquisition module 203 is used to obtain the electromagnetic wave signal reflectivity of each test point of each part based on the electromagnetic wave incident signal intensity and the electromagnetic wave reflected signal intensity. The detection module 204 is used to obtain the assembly quality inspection result of each part based on the electromagnetic wave signal reflectivity and the electromagnetic wave reflection signal curve. The assembly quality inspection result includes assembly qualified and assembly unqualified.

[0082] The system in this embodiment can comprehensively inspect multiple test points at different parts of cable accessories through electromagnetic wave reflection testing. It can also deeply inspect the internal structure of cable accessories, accurately detect assembly defects, obtain the intensity of electromagnetic wave reflection signals, construct electromagnetic wave reflection signal curves, and calculate electromagnetic wave reflection rates. Based on the electromagnetic wave reflection rates and electromagnetic wave reflection signal curves, the system can obtain the assembly quality inspection results for each part, accurately determine whether the assembly is qualified, and is not affected by subjective factors. This achieves comprehensive and accurate inspection of the assembly quality of cable accessories, effectively improving inspection efficiency and accuracy, reducing the risk of power failure, ensuring the safe and stable operation of the cable system, and reducing economic losses and safety hazards.

[0083] In a specific embodiment, the third embodiment of this application provides a cable accessory assembly quality inspection device based on electromagnetic waves, including a memory and a processor. The memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the method as described in any one of the first embodiments of this application.

[0084] In a specific embodiment, the fourth embodiment of this application provides a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the method as described in any one of the first embodiments of this application.

[0085] The above embodiments merely illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for inspecting the assembly quality of cable accessories based on electromagnetic waves, characterized in that, The method includes: Electromagnetic wave reflection tests were performed on different test points at different parts of the cable accessories to obtain the electromagnetic wave incident signal intensity and electromagnetic wave reflected signal intensity at different test points of each part during the electromagnetic wave reflection test. The electromagnetic wave incident signal intensity and the electromagnetic wave reflected signal intensity are transformed from the frequency domain to the time domain to obtain the electromagnetic wave incident signal intensity and the electromagnetic wave reflected signal intensity in the time domain. Set the start and end times of the time window according to the electromagnetic wave transmission time matched by the length of the electromagnetic wave transmission line, and record the peak time of the electromagnetic wave reflection signal intensity in the time domain at each test point. Based on the electromagnetic wave incident signal intensity and the electromagnetic wave reflected signal intensity in the time domain, the electromagnetic wave signal reflectivity of each test point in each part is obtained; The reflectance variation of each test point at each location is obtained based on the electromagnetic wave signal reflectance and the preset standard reflectance; the standard reflectance is the electromagnetic wave signal reflectance of different locations of the assembled qualified cable accessories. The peak time difference for each part is obtained based on the peak time and the preset standard time; the preset standard time is the peak time when the peak electromagnetic wave reflection signal intensity of different parts of the assembled qualified cable accessories appears. The assembly quality inspection results for each part are obtained based on the change in reflectivity and the peak time difference; the assembly quality inspection results include qualified assembly and unqualified assembly.

2. The method for inspecting the assembly quality of cable accessories based on electromagnetic waves as described in claim 1, characterized in that, The process of obtaining the assembly quality inspection results for each part based on the reflectivity change and the peak time difference includes: If the first reflectivity change at the stress cone and the second reflectivity change at the inner electrode of the cable accessory are both less than or equal to the first preset threshold, and the first peak time difference at the stress cone and the second peak time difference at the inner electrode are both less than or equal to the second preset threshold and greater than or equal to the third preset threshold, then the assembly quality inspection result of the cable accessory is qualified; the third preset threshold is less than the second preset threshold. If the first reflectance change is greater than the first preset threshold or the second reflectance change is greater than the first preset threshold, and the first peak time difference is greater than the second preset threshold, then the assembly quality test result of the stress cone part is unqualified. If the first reflectance change is greater than the first preset threshold or the second reflectance change is greater than the first preset threshold, and the second peak time difference is less than the third preset threshold, then the assembly quality test result of the inner electrode part is unqualified.

3. The method for inspecting the assembly quality of cable accessories based on electromagnetic waves as described in claim 2, characterized in that, The first preset threshold, the second preset threshold, and the third preset threshold are obtained using the following formula: ， in, δ The first preset threshold, The second preset threshold, The third preset threshold, The peak value of the incident electromagnetic wave signal intensity. The start time of the time window set for the electromagnetic wave propagation time during electromagnetic wave reflection testing. The end time of the time window set for the electromagnetic wave propagation time during electromagnetic wave reflection testing. The number of sampling data points set during time-domain transformation.

4. The method for inspecting the assembly quality of cable accessories based on electromagnetic waves as described in claim 1, characterized in that, The reflectivity of the electromagnetic wave signal is obtained using the following formula: in, The reflectivity of the electromagnetic wave signal is... The intensity of the incident electromagnetic wave signal. The intensity of the reflected electromagnetic wave signal is denoted as .

5. A cable accessory assembly quality inspection device based on electromagnetic waves, comprising a memory and a processor, characterized in that, The memory stores a computer program that, when executed by the processor, causes the processor to perform the steps of the method as described in any one of claims 1 to 4.

6. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it causes the processor to perform the steps of the method as described in any one of claims 1 to 4.

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