Method for detecting impurity defect of 10kV cable terminal wrapping tape

Abstract

The 10kV cable terminal wrapping tape impurity defect detection method provided by the invention comprises the steps that a high-frequency microwave signal is transmitted to a wrapping tape part of a 10kV to-be-evaluated cable terminal, a reflection coefficient curve of a reflection wave is acquired, and the frequency band of the high-frequency microwave signal is 22GHz-30GHz; selecting a preset number of minimum values from the reflection coefficient curve as to-be-evaluated reflection characteristic values, and selecting a corresponding defect-free reflection characteristic value according to the frequency of each to-be-evaluated reflection characteristic value; calculating a difference absolute value according to each to-be-evaluated reflection characteristic value and each defect-free reflection characteristic value, and calculating a defect characteristic offset factor according to the difference absolute value; and according to each to-be-evaluated reflection characteristic value and the defect characteristic offset factor, calculating a wrapping tape impurity defect characterization parameter, and performing defect evaluation on the wrapping tape part of the to-be-evaluated cable terminal through the wrapping tape impurity defect characterization parameter. In this way, the impurity defect of the cable terminal wrapping tape area can be efficiently identified.

Description

Technical Field

[0001] The present application relates to the technical field of cable intermediate joint detection and evaluation, and in particular to a method for detecting impurity defects in the wrapping tape of a 10kV cable terminal. Background Art

[0002] With the continued expansion of urban construction and electricity consumption, society's demand for electricity continues to grow, along with increasing requirements for power quality and reliability. Cross-linked polyethylene (XLPE) cables, due to their excellent mechanical and electrical properties, flexible routing, easy installation, and high safety, have become widely used in power transmission systems such as urban power grids and rail transit. As key components in cable lines, cable terminals not only regulate the electric field distribution at the ends of the cable's insulation and shielding, ensuring the normal operation of the cable system, but also securely connect the cable to electrical equipment, thereby maintaining stable power transmission.

[0003] However, during the actual installation of cable terminals, due to inadequate construction process control or insufficient cleanliness in the installation environment, foreign matter such as metal particles and dust can easily remain at the critical interface between the sealant and the semi-conductive tape. These impurities may have a high dielectric constant or conductivity, disrupting the uniformity of the local electric field distribution and affecting the long-term stability of the insulation structure. Over time, impurities trapped in the wrapping tape can cause electric field distortion and form persistent local discharge channels. Local discharges gradually degrade the insulation material, ultimately causing breakdown failures, leading to power outages and compromising the safe operation of the power system.

[0004] Currently, research on detecting impurity defects in 10kV cable wrapping tape is limited, and mature, efficient application methods are still lacking. Therefore, a reliable defect detection method is urgently needed to assist operators and maintenance personnel in promptly assessing the service status of cable terminals after installation. This is crucial for ensuring stable operation of cable systems and improving equipment efficiency. Summary of the Invention

[0005] The purpose of this application is to solve at least one of the above technical deficiencies, in particular the technical deficiency in the prior art of how to reliably detect impurity defects in 10kV cable wrapping tapes.

[0006] In a first aspect, the present application provides a method for detecting impurity defects in a 10kV cable terminal wrapping tape, the method comprising:

[0007] A high-frequency microwave signal is emitted to the wrapping tape of the 10kV cable terminal to be evaluated, and the reflection coefficient curve of the reflected wave is obtained. The frequency range of the high-frequency microwave signal is 22GHz~30GHz.

[0008] Selecting a preset number of minimum values ​​from the reflection coefficient curve as reflection characteristic values ​​to be evaluated, and selecting a corresponding defect-free reflection characteristic value according to the frequency of each reflection characteristic value to be evaluated;

[0009] Calculating the absolute value of the difference between each reflection characteristic value to be evaluated and each defect-free reflection characteristic value, and calculating the defect characteristic offset factor based on the absolute value of the difference;

[0010] According to each reflection characteristic value to be evaluated and the defect characteristic offset factor, the impurity defect characterization parameter of the wrapping tape is calculated, and the defect evaluation of the wrapping tape part of the cable terminal to be evaluated is performed through the impurity defect characterization parameter of the wrapping tape.

[0011] In one embodiment, the step of transmitting a high-frequency microwave signal to the wrapping tape portion of a 10 kV cable terminal to be evaluated includes:

[0012] A vector network analyzer is used to transmit a high-frequency microwave signal to the 10kV cable terminal to be evaluated, so that the high-frequency microwave signal is transmitted through the coaxial cable and rectangular waveguide and then vertically enters the wrapping tape part of the cable terminal to be evaluated.

[0013] In one embodiment, the step of calculating the absolute value of the difference based on each reflection characteristic value to be evaluated and each defect-free reflection characteristic value includes:

[0014] The absolute value of the difference is calculated as follows:

[0015]

[0016] in, Indicates the The absolute value of the difference, Indicates the The difference between the reflection characteristic value to be evaluated and its corresponding defect-free reflection characteristic value, Indicates the reflection eigenvalues ​​to be evaluated, Indicates the defect-free reflection characteristic values.

[0017] In one embodiment, the step of calculating the defect feature offset factor according to the absolute value of the difference includes:

[0018] The defect feature shift factor is calculated as follows:

[0019]

[0020] in, represents the defect feature shift factor, Indicates the absolute value of the difference.

[0021] In one embodiment, the step of calculating the impurity defect characterization parameter of the wrapping tape according to each reflection characteristic value to be evaluated and the defect characteristic offset factor includes:

[0022] The characterization parameters of impurity defects in the wrapping tape are calculated according to the following expression:

[0023]

[0024] in, It represents the parameter characterizing the impurity defect of the wrapping tape. represents the defect feature shift factor, Indicates the The reflection eigenvalues ​​to be evaluated.

[0025] In one embodiment, the step of performing defect assessment on the wrapping tape portion of the cable terminal to be assessed using wrapping tape impurity defect characterization parameters includes:

[0026] When the impurity defect characterization parameter of the wrapping tape is not greater than the first preset threshold value, the wrapping tape portion of the cable terminal to be evaluated is free of impurities;

[0027] When the defect characterization parameter of the wrapping tape impurities is greater than the first preset threshold value and not greater than the second preset threshold value, the wrapping tape portion of the cable terminal to be evaluated contains dust impurities;

[0028] When the defect characterization parameter of the wrapping tape impurities is greater than the second preset threshold, the wrapping tape portion of the cable terminal to be evaluated contains metal impurities.

[0029] In one embodiment, the first preset threshold is 3.817, and the second preset threshold is 5.639.

[0030] In a second aspect, the present application provides a device for detecting impurity defects in a 10kV cable terminal wrapping tape, the device comprising:

[0031] The reflection coefficient curve acquisition module is used to transmit a high-frequency microwave signal to the wrapping tape of the 10kV cable terminal to be evaluated and obtain the reflection coefficient curve of the reflected wave. The frequency band of the high-frequency microwave signal is 22GHz to 30GHz.

[0032] A reflection characteristic value selection module is used to select a preset number of minimum values ​​from the reflection coefficient curve as the reflection characteristic values ​​to be evaluated, and select the corresponding defect-free reflection characteristic value according to the frequency of each reflection characteristic value to be evaluated;

[0033] A defect feature offset factor calculation module is used to calculate the absolute value of the difference between each reflection feature value to be evaluated and each defect-free reflection feature value, and calculate the defect feature offset factor based on the absolute value of the difference;

[0034] The wrapping tape impurity defect assessment module is used to calculate the wrapping tape impurity defect characterization parameters based on each reflection characteristic value to be evaluated and the defect characteristic offset factor, and to perform defect assessment on the wrapping tape part of the cable terminal to be evaluated through the wrapping tape impurity defect characterization parameters.

[0035] In a third aspect, the present application provides a storage medium: the storage medium stores computer-readable instructions, and when the computer-readable instructions are executed by one or more processors, the one or more processors execute the steps of the 10kV cable terminal wrapping tape impurity defect detection method as described in any one of the above embodiments.

[0036] In a fourth aspect, the present application provides a computer device, comprising: one or more processors, and a memory;

[0037] The memory stores computer-readable instructions, and when the computer-readable instructions are executed by one or more processors, the steps of the method for detecting impurity defects in the 10kV cable terminal wrapping tape in any one of the above embodiments are performed.

[0038] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0039] The 10kV cable terminal wrapping tape impurity defect detection method provided in this application can realize the efficient identification of impurity defects in the cable terminal wrapping tape area without destroying the cable structure, and has obvious technical effects. First, by emitting a high-frequency microwave signal in the 22GHz~30GHz frequency band to the cable terminal wrapping tape part and obtaining a reflection coefficient curve, non-contact detection of the electromagnetic response characteristics inside the wrapping structure can be achieved, avoiding the risk of secondary damage caused by the cable disassembly inspection, and improving the safety and convenience of the detection process. Secondly, a preset number of minimum values ​​are selected from the reflection coefficient curve as reflection characteristic values, and combined with the standard characteristic values ​​under the corresponding defect-free working conditions, the electromagnetic characteristic changes caused by the presence of impurities in the wrapping tape structure can be accurately captured, thereby improving the sensitivity and accuracy of defect identification. Furthermore, by calculating the defect characteristic offset factor by the absolute value of the difference, the degree of impurity disturbance to the electric field can be quantified, so that the detection process has a clear numerical indication basis, which helps to achieve a graded assessment of the severity of impurity defects. Finally, by constructing the impurity defect characterization parameters of the wrapping tape and conducting quantitative evaluation, it can provide operation and maintenance personnel with an intuitive and reliable basis for defect identification, timely discover potential hidden dangers, thereby effectively reducing the risk of insulation degradation or breakdown failure caused by impurities, and improving the safety and reliability of the overall operation of the cable terminal, which has important engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] 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 or the description of the prior art. 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 paying any creative labor.

[0041] Figure 1 A schematic flow chart of a method for detecting impurity defects in a 10kV cable terminal wrapping tape according to an embodiment of the present application;

[0042] Figure 2 A schematic diagram of the structure of a device for detecting impurity defects in a 10kV cable terminal wrapping tape according to an embodiment of the present application;

[0043] Figure 3 A schematic diagram of the internal structure of a computer device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0044] 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.

[0045] This application provides a method for detecting impurity defects in the wrapping tape of a 10kV cable terminal. The following embodiments are described using the method applied to a computer device as an example. It is understood that the computer device can be any device with data processing capabilities, including but not limited to a single server, a server cluster, a personal laptop computer, a desktop computer, etc. Figure 1 As shown, the method may include the following steps:

[0046] S101: A high-frequency microwave signal is emitted toward the wrapping tape of the 10 kV cable terminal to be evaluated, and a reflection coefficient curve of the reflected wave is obtained. The frequency range of the high-frequency microwave signal is 22 GHz to 30 GHz.

[0047] The cable terminal to be evaluated refers to a cable terminal structure used in 10kV cross-linked polyethylene (XLPE) cable systems during the evaluation or maintenance inspection phase. It includes multiple functional components, such as stress cones, wrapping tape, and sealant, to achieve electrical connection and electric field control between the cable and electrical equipment. The wrapping tape area refers to the area of ​​the cable terminal where the semiconductor tape or insulating tape is wrapped around the main insulation for further voltage equalization and sealing. This area, often located outside the stress cone, is a sensitive location prone to impurity retention and electric field distortion. High-frequency microwave signals are electromagnetic waves with a frequency range of 22 GHz to 30 GHz. This frequency band has a short wavelength and limited penetration, making it suitable for non-contact, high-resolution inspection of cable surface coverings. The reflection coefficient curve of the reflected wave is the frequency domain response data generated by the electromagnetic structure within the cable wrapping tape to the incident signal under the action of a microwave signal. Collecting this response curve can reveal the electromagnetic characteristics and structural integrity of the measured area.

[0048] Specifically, the computer equipment may include a detection terminal equipped with signal control, data acquisition, and processing capabilities, connected to a microwave detection device integrated with a radio frequency transmitter and receiver. During testing, the port of the microwave detection device is attached to the outer surface of the tape wrapping of the cable terminal to be evaluated, ensuring close contact between the probe and the cable surface to minimize signal attenuation and interference errors. The computer equipment then controls the detection device to operate within a frequency range of 22 GHz to 30 GHz, transmitting high-frequency microwave signals at preset frequency steps point by point, injecting the microwave signals radially and perpendicularly into the tape wrapping.

[0049] Subsequently, a computer receives the signal reflected from the wrapping tape structure in real time, uses a network analyzer to obtain the complex reflection coefficient value at each frequency point, and plots the reflection coefficient values ​​corresponding to each frequency point into a complete reflection coefficient curve. This reflection curve can reflect the electromagnetic response characteristics of the target wrapping area and is used for defect feature identification.

[0050] Furthermore, to improve data processing efficiency, after acquiring the reflection coefficient curve, the computer can use a built-in Fourier transform module or noise filtering algorithm to perform noise reduction and feature enhancement on the original curve. By setting curve minimum selection criteria, such as downstream envelope interception or curvature change detection, several representative minimum points in the reflection curve can be accurately extracted, providing basic reflection feature data for defect analysis.

[0051] It can be understood that emitting high-frequency microwave signals in the 22 GHz to 30 GHz frequency range effectively stimulates the electromagnetic response characteristics of the cable terminal wrapping tape. Due to the short wavelength of the signal in this frequency range, it is highly sensitive to microstructural changes and is particularly suitable for identifying small defects in the wrapping tape. Collecting the reflected signal in the frequency domain and constructing a reflection coefficient curve can visually demonstrate the impact of impurities on local electromagnetic properties, thereby assisting in analyzing the areas of electric field distortion they may cause. Furthermore, the use of non-contact microwave detection eliminates the need for cable disassembly, greatly improving the safety and adaptability of the inspection process. This method not only improves the efficiency of cable terminal assessment and reduces the risk of manual intervention, but also enables high-precision and repeatable electromagnetic signature acquisition, providing a stable and reliable raw data foundation for defect identification and diagnosis, with significant engineering applicability and promotional value.

[0052] S102: selecting a preset number of minimum values ​​from the reflection coefficient curve as reflection characteristic values ​​to be evaluated, and selecting a corresponding defect-free reflection characteristic value according to the frequency of each reflection characteristic value to be evaluated.

[0053] The preset number of minimum values ​​refers to a number of local minimum reflection points automatically identified from the reflection coefficient curve according to a set number of selections, representing characteristic locations where structural changes or impurity influences may exist. The reflection characteristic value to be evaluated refers to the reflection coefficient value at the frequency point corresponding to the above minimum value, which is used to reflect the actual electromagnetic response of the cable terminal under test at that frequency point. The defect-free reflection characteristic value refers to the standard reflection coefficient value measured at the same frequency point by a standard cable terminal known to be free of impurity defects. It serves as a comparative reference baseline to identify whether the cable terminal has abnormal reflection behavior.

[0054] Specifically, after the computer device completes acquisition of the reflection coefficient curve by controlling the signal acquisition module, it can activate the feature extraction module to perform a minimum value identification operation on the curve. To improve the stability and noise resistance of feature identification, the original reflection coefficient curve can first be smoothed and filtered, such as by using a sliding average, Savitzky-Golay filter, or wavelet denoising algorithm to eliminate high-frequency noise interference and retain the main change trend.

[0055] After curve preprocessing, the computer identifies local minima on the curve based on predefined minimum selection rules, such as points where the first-order derivative is zero and the second-order derivative is greater than zero. A selection number, N, can be set as a parameter input to automatically select the first N candidate minimum points with the smallest reflection coefficients as the reflection feature values ​​to be evaluated. Furthermore, to ensure the rational distribution of feature points in the frequency domain, frequency spacing constraints or peak difference limits can be added to prevent highly concentrated feature points or redundant information from being selected.

[0056] Furthermore, for each selected reflection characteristic value to be evaluated, the computer device can retrieve a reference reflection dataset of defect-free cable terminations stored in a database and select the defect-free reflection characteristic value corresponding to that frequency point. This database can be established through extensive preliminary experiments and correlated with parameters such as cable model, structure, and wrapping tape material to ensure the adaptability of the matching data and the effectiveness of the comparison.

[0057] It can be understood that by selecting a preset number of minimum values ​​in the reflection coefficient curve as the reflection characteristic values ​​to be evaluated, it is possible to concentrate on extracting the most sensitive points in the curve that can reflect structural response anomalies, simplifying data processing while significantly improving the focus and efficiency of defect identification. Furthermore, obtaining the standard reflection characteristic values ​​under defect-free conditions at these characteristic frequency points as a reference can minimize the impact of non-structural factors such as environmental interference and material differences on the comparison results, achieving objectivity and pertinence in the difference comparison. Overall, this method not only improves the degree of automation of defect location and feature extraction, but also enhances the system's ability to resolve the effects of tiny impurities, helping to achieve high-precision cable terminal quality assessment and defect warning, and has good engineering feasibility and practical application value.

[0058] S103: Calculating the absolute value of the difference according to each reflection characteristic value to be evaluated and each defect-free reflection characteristic value, and calculating the defect characteristic offset factor according to the absolute value of the difference.

[0059] The absolute value of the difference is the absolute value of the difference between each reflection characteristic value to be evaluated and its corresponding defect-free reflection characteristic value, and is used to quantify the degree of deviation in the reflection response. The defect characteristic deviation factor is a quantitative indicator reflecting the overall deviation of the defect, derived by combining the absolute values ​​of each difference. It serves as the core basis for determining the severity of impurity defects in the wrapping tape.

[0060] After matching the reflectance eigenvalues ​​to be evaluated with the corresponding defect-free reflectance eigenvalues, the computer device can call on the built-in calculation module to perform differential absolute value calculations on each pair of eigenvalues ​​in turn. To enhance the overall representation of abnormal offsets, the computer device can further normalize the sequence of differential absolute values ​​to eliminate the influence of reflectance magnitude under different test conditions, for example, by using maximum normalization or Z-score normalization to achieve a uniform scale.

[0061] After normalization, the computer combines the absolute values ​​of the differences according to a predefined weighting model or average fusion strategy to calculate a defect signature offset factor. For example, the offset factor can be simply calculated as the arithmetic mean of the absolute values ​​of the differences, or an exponentially weighted average can be constructed to enhance the response to significant differences. Once calculated, this defect signature offset factor serves as a numerical measure of the abnormal degree of impurities in the cable terminal tape and is subsequently used by the defect assessment module.

[0062] In this embodiment, by calculating the absolute difference between the reflection characteristic value to be evaluated and the defect-free reflection characteristic value, and using this as a basis to calculate the defect characteristic offset factor, the degree of deviation of the electromagnetic response of the cable terminal at the target frequency point can be effectively quantified, thereby accurately reflecting the electromagnetic disturbance caused by minor structural anomalies or impurities that may exist in the wrapping tape. This method does not rely on image processing or subjective judgment, has clear numerical logic and a stable calculation process, and helps to achieve the automation and standardization of cable terminal defect assessment. The unified offset factor indicator can significantly improve the comparability of detection results between multiple devices, providing a reliable quantitative basis for intelligent inspection and early warning of power systems, and further improving the accuracy and efficiency of cable operation and maintenance management.

[0063] S104: Calculate the impurity defect characterization parameter of the wrapping tape according to each reflection characteristic value to be evaluated and the defect characteristic offset factor, and perform defect evaluation on the wrapping tape portion of the cable terminal to be evaluated using the impurity defect characterization parameter of the wrapping tape.

[0064] Among them, the impurity defect characterization parameter of the wrapping tape refers to a quantitative indicator calculated by computer equipment based on the reflection characteristic value to be evaluated and the defect characteristic offset factor. It is used to comprehensively reflect the degree of abnormality of the electromagnetic characteristics caused by impurity residues in the cable terminal wrapping tape area. It is the core parameter for defect assessment.

[0065] Specifically, after obtaining the sequence of reflective feature values ​​to be evaluated and the corresponding defect feature offset factors, the computer device can call the defect characterization module to perform calculations on the defect characterization parameters. For example, each reflective feature value to be evaluated is multiplied by its corresponding or uniformly weighted defect feature offset factor to form a weighted offset value sequence. This weighted offset value sequence is then normalized and a single numerical indicator is generated using algorithms such as averaging, weighted fusion, or principal component analysis (PCA) to serve as the tape impurity defect characterization parameter.

[0066] After calculating the defect characterization parameters, the computer device can activate the defect assessment module to compare the parameters with a pre-established defect-free baseline interval or a multi-level threshold model. The threshold model can be set based on historical sample statistics, manual annotation experience, or standard operating condition test data, and divided into multiple levels such as "normal," "minor defect," "moderate defect," and "severe defect" to provide differentiated diagnostic results.

[0067] It can be understood that by calculating the impurity defect characterization parameter of the wrapping tape based on the reflection characteristic value to be evaluated and the defect characteristic offset factor, and using this parameter as a unified indicator for defect evaluation, the local abnormality information of multiple frequency domain characteristic points can be effectively integrated and converted into a single quantifiable and comparable comprehensive diagnostic result, thereby simplifying the evaluation process and improving judgment efficiency.

[0068] In the above embodiment, it is possible to achieve efficient identification of impurity defects in the cable terminal wrapping tape area without destroying the cable structure, which has obvious technical effects. First, by emitting a high-frequency microwave signal in the 22GHz~30GHz frequency band to the cable terminal wrapping tape part and obtaining a reflection coefficient curve, it is possible to achieve non-contact detection of the electromagnetic response characteristics inside the wrapping structure, avoiding the risk of secondary damage caused by cable disassembly inspection, and improving the safety and operational convenience of the detection process. Secondly, by selecting a preset number of minimum values ​​from the reflection coefficient curve as reflection characteristic values, combined with the standard characteristic values ​​under the corresponding defect-free working conditions, it is possible to accurately capture the changes in electromagnetic characteristics caused by the presence of impurities in the wrapping tape structure, thereby improving the sensitivity and accuracy of defect identification. Furthermore, by calculating the defect characteristic offset factor through the absolute value of the difference, the degree of impurity disturbance to the electric field can be quantified, so that the detection process has a clear numerical indication basis, which helps to achieve a graded assessment of the severity of impurity defects. Finally, by constructing the impurity defect characterization parameters of the wrapping tape and conducting quantitative evaluation, it can provide operation and maintenance personnel with an intuitive and reliable basis for defect identification, timely discover potential hidden dangers, thereby effectively reducing the risk of insulation degradation or breakdown failure caused by impurities, and improving the safety and reliability of the overall operation of the cable terminal, which has important engineering application value.

[0069] In one embodiment, the step of transmitting a high-frequency microwave signal to the wrapping tape portion of a 10 kV cable terminal to be evaluated includes:

[0070] A vector network analyzer is used to transmit a high-frequency microwave signal to the 10kV cable terminal to be evaluated, so that the high-frequency microwave signal is transmitted through the coaxial cable and rectangular waveguide and then vertically enters the wrapping tape part of the cable terminal to be evaluated.

[0071] A vector network analyzer (VNA) is an electromagnetic parameter measurement device capable of transmitting and receiving radio frequency signals. It generates high-frequency microwave signals and measures their reflection and transmission characteristics within the object under test. It is a core device for high-frequency signal injection and response analysis. A coaxial cable is a high-frequency transmission medium used to connect the VNA and waveguide, effectively transmitting microwave signals and maintaining signal stability. A rectangular waveguide is a metal cavity structure with a rectangular cross-section, designed for low-loss transmission of high-frequency microwaves. It enables spatial guidance and directional control of microwave signals.

[0072] Specifically, the computer is equipped with a control interface module that establishes a communication connection with the vector network analyzer, automating the signal transmission process. During operation, the microwave scanning frequency band is set according to the task parameters, and the vector network analyzer is instructed to generate a high-frequency microwave signal covering the frequency range of 22 GHz to 30 GHz. The signal transmitter is connected to the rectangular waveguide via a calibrated coaxial cable.

[0073] To achieve high-precision and high-stability injection, the computer guides the operator to vertically align the open end of the rectangular waveguide with the taped portion of the 10kV cable terminal, ensuring a close fit between the waveguide outlet and the cable surface and minimizing reflection interference caused by air gaps or tilt angles. Mechanical fixation can be achieved using a probe holder or positioning fixture, while a posture detection module, such as a laser planarization instrument or inclinometer, is activated to perform directional correction, ensuring that the microwave signal is stably and vertically injected into the target area.

[0074] Furthermore, the computer receives parameter data returned by the vector network analyzer in real time, including frequency-domain characteristics such as reflection and transmission coefficients. This data is then used to construct reflection coefficient curves and identify defect response characteristics. Parameters such as frequency step size, sweep speed, and transmit power are all set uniformly by the computer to ensure data quality and detection consistency.

[0075] In this embodiment, by controlling the vector network analyzer to emit high-frequency microwave signals and utilizing coaxial cables and rectangular waveguides to stably guide the microwave energy to the cable terminal's wrapping tape, this not only avoids the risk of secondary damage from cable structural disintegration but also enables non-contact, high-resolution detection of the local electromagnetic characteristics of the wrapping area. In particular, the vertical incidence method minimizes energy attenuation and multipath reflection caused by the incident angle, improving signal injection efficiency and detection accuracy. Overall, this method, while ensuring equipment compatibility and detection sensitivity, contributes to the establishment of a standardized and automated cable terminal inspection process, significantly improving the operational convenience and engineering feasibility of defect detection.

[0076] In one embodiment, the step of calculating the absolute value of the difference based on each reflection characteristic value to be evaluated and each defect-free reflection characteristic value includes:

[0077] The absolute value of the difference is calculated as follows:

[0078]

[0079] in, Indicates the The absolute value of the difference, Indicates the The difference between the reflection characteristic value to be evaluated and its corresponding defect-free reflection characteristic value, Indicates the reflection eigenvalues ​​to be evaluated, Indicates the defect-free reflection characteristic values.

[0080] As can be understood, this differential absolute value calculation method objectively quantifies deviations in the local electromagnetic response of the cable terminal wrapping tape caused by impurities or structural anomalies, providing a precise and intuitive numerical indicator for defect identification. The use of absolute values ​​avoids the phenomenon of positive and negative offsets, ensuring that all abnormal deviations are effectively accounted for in the analysis. This method facilitates automated calculation and batch processing, improves the sensitivity and accuracy of defect detection, supports differentiation of different defect types and severities, and significantly enhances the reliability and practical value of cable terminal quality assessment.

[0081] In one embodiment, the step of calculating the defect feature offset factor according to the absolute value of the difference includes:

[0082] The defect feature shift factor is calculated as follows:

[0083]

[0084] in, represents the defect feature shift factor, Indicates the absolute value of the difference.

[0085] Specifically, the formula adopts a composite structure of logarithmic function and exponential function to realize the joint expression of overall offset and fluctuation amplitude. The numerator controls the growth rate of the value range by taking the logarithm of the total offset to avoid amplification of abnormal points. The denominator constructs an exponential function through the range to amplify and penalize the fluctuation between frequency points, thereby enhancing the sensitivity to unstable offset.

[0086] Calculating the defect signature offset factor using the above formula fully considers the overall offset intensity while introducing a penalty mechanism for fluctuations between frequency points. This allows the defect signature offset factor to not only reflect the cumulative effects of anomalies caused by impurities in the cable terminal wrapping area, but also identify imbalances in electromagnetic response consistency. A logarithmic function is used in the numerator to suppress the effects of large offsets, enhancing the resolution of low- to medium-range offset anomalies. An exponential function is used in the denominator to amplify the range, improving the ability to suppress abnormally large fluctuations, thereby avoiding the risk of misjudgment due to localized ranges masking overall offsets.

[0087] Overall, this formula has the advantages of strong robustness, numerical controllability, and high diagnostic sensitivity. It is easy to deploy in an automated detection system in a standardized manner, and can achieve stable and refined quantitative evaluation of the defect status of cable terminals. It helps to improve the accuracy of defect identification and the consistency of system judgment, and has significant engineering applicability and practical promotion value.

[0088] In one embodiment, the step of calculating the impurity defect characterization parameter of the wrapping tape according to each reflection characteristic value to be evaluated and the defect characteristic offset factor includes:

[0089] The characterization parameters of impurity defects in the wrapping tape are calculated according to the following expression:

[0090]

[0091] in, It represents the parameter characterizing the impurity defect of the wrapping tape. represents the defect feature shift factor, Indicates the The reflection eigenvalues ​​to be evaluated.

[0092] Specifically, the formula adopts a weighted hybrid structure, integrating information on defect intensity and response structure asymmetry in the numerator, and normalizes the denominator through the cube root function to form a comprehensive characterization value under a unified scale.

[0093] By using the above expression to calculate the parameters characterizing impurity defects in the wrapping tape, it is possible to accurately reflect the impact of possible tiny impurities in the cable terminal wrapping tape on the electromagnetic wave propagation characteristics in multiple dimensions. In the numerator, the 2 / 3 power term of the defect characteristic offset factor prevents over-amplification of the defect intensity information while retaining its sensitivity. Taking the logarithm of the reflection value deviation further reveals the asymmetry between frequency points and the overall low trend, enhancing the ability to identify local hidden impurity disturbances.

[0094] Furthermore, the cube root form of the range in the denominator introduces a normalized constraint on the frequency domain fluctuation amplitude, making the numerical expression of the tape impurity defect characterization parameter smooth and comparable, effectively avoiding misjudgments caused by distortion at specific frequencies. Compared to a single characteristic parameter, the tape impurity defect characterization parameter, as a comprehensive parameter integrating multi-level information, can provide a more accurate and detailed assessment of the cable terminal structural integrity.

[0095] Therefore, this calculation method not only improves the sensitivity of impurity defect identification, but also enhances the system's adaptability to tiny abnormal changes in complex electromagnetic response patterns, providing a solid numerical foundation for building an automated and standardized cable quality assessment system, and has good engineering practicality and scalability.

[0096] In one embodiment, the step of performing defect assessment on the wrapping tape portion of the cable terminal to be assessed using wrapping tape impurity defect characterization parameters includes:

[0097] When the impurity defect characterization parameter of the wrapping tape is not greater than the first preset threshold value, the wrapping tape portion of the cable terminal to be evaluated is free of impurities;

[0098] When the defect characterization parameter of the wrapping tape impurities is greater than the first preset threshold value and not greater than the second preset threshold value, the wrapping tape portion of the cable terminal to be evaluated contains dust impurities;

[0099] When the defect characterization parameter of the wrapping tape impurities is greater than the second preset threshold, the wrapping tape portion of the cable terminal to be evaluated contains metal impurities.

[0100] The first preset threshold refers to the critical value for impurity identification, determined through extensive experimental data and statistical analysis. When this value is not exceeded, it indicates that no abnormal response has been detected within the detection area. The second preset threshold refers to the identification critical value between the normal state and the severe impurity contamination state, which is used to further refine the impurity type. Dust impurities refer to non-conductive particles or dust-like foreign matter that may remain on the interface of the wrapping tape during installation and have a moderate impact on microwave reflection characteristics. Metal impurities refer to metal particles with a high dielectric constant or conductivity. They may significantly disturb the electric field distribution and cause strong reflection changes, and are a more dangerous defect type.

[0101] It should be noted that, in one embodiment, the first preset threshold is 3.817, and the second preset threshold is 5.639. Both the first preset threshold 3.817 and the second preset threshold 5.639 are empirical parameters obtained through a large amount of experimental data fitting and statistical analysis, and are used to distinguish the degree of impurity defects in the cable terminal wrapping tape. On the one hand, its value is combined with multiple known states, such as actual detection data of cable terminal samples such as no impurities, dust impurities, metal particle impurities, etc., to calculate the corresponding distribution range of the parameter value of the impurity defect characterization of the wrapping tape, and use the statistical interval of the distribution boundary to determine the reasonable dividing point. Through normalization processing, fluctuation suppression and response quantification, it is found that when the parameter characterization of the impurity defect of the wrapping tape is When the reflection response in the sample is stable, the fluctuation amplitude is small, and the microwave characteristic value offset is not significant, which is consistent with the characteristics of the impurity-free state; when the wrapping tape impurity defect characterization parameter λ is greater than 5.639, the sample mostly contains metal particles with strong electromagnetic perturbation effects, and its reflection curve is severely distorted, with large electric field non-uniformity. Therefore, this value is set as the lower limit for the judgment of metal impurities. On the other hand, the middle range ( ) corresponds to low-dielectric, non-conductive dust or impurity residues. The microwave disturbances they generate are in the intermediate, recognizable but not intense range, and are therefore classified as dust impurity, facilitating automatic distinction between impurity types. Therefore, the setting of these two thresholds combines theoretical models with actual sample statistics, ensuring both a physical rationality of the judgment results and good engineering stability and adaptability for widespread application. They can be directly applied to computer equipment for the automated identification and intelligent assessment of cable terminal tape defects.

[0102] Specifically, the computer device includes a defect recognition module that receives and analyzes the numerical values ​​of parameters characterizing impurity defects in the wrapping tape and compares them with multiple built-in thresholds. The system pre-stores a first and second preset threshold, which are used to classify the three judgment results as "no impurities," "contains dust impurities," and "contains metal impurities," respectively.

[0103] In practice, once the computer completes microwave signal acquisition and defect characterization parameter calculations for the wrapped tape, the judgment logic process is automatically triggered. First, it determines whether λ is less than or equal to a first preset threshold. If so, a "no impurities" assessment result is output. If λ is greater than the first threshold and does not exceed the second threshold, the area is identified as "contains dust impurities." If λ is greater than the second preset threshold, the system determines that the current area contains "metal impurities."

[0104] It can be understood that by comparing the impurity defect characterization parameters of the wrapping tape with multiple preset thresholds in sections, it is possible to achieve automated and graded identification of the impurity status of the wrapping tape, which helps to distinguish between the three risk levels of normal operating conditions, mild contamination, and severe impurities, and improve the certainty of judgment. The use of a multi-threshold discrimination mechanism can effectively improve the system's recognition accuracy of the differences in electromagnetic responses caused by different types of impurities. At the same time, this method takes into account the subtlety of judgment and engineering operability, not only improving the accuracy and responsiveness of defect detection, but also enhancing the practicality and credibility of the detection system in actual on-site deployment. Ultimately, this processing flow can provide operation and maintenance personnel with clear and actionable judgment results, supporting more timely defect repair and system security assurance.

[0105] The following describes the 10kV cable terminal wrapping tape impurity defect detection device provided by the embodiment of the present application. The 10kV cable terminal wrapping tape impurity defect detection device described below and the 10kV cable terminal wrapping tape impurity defect detection method described above can be used for reference. Figure 2 As shown, the present application provides a 10kV cable terminal wrapping tape impurity defect detection device, the device comprising:

[0106] The reflection coefficient curve acquisition module 201 is used to transmit a high-frequency microwave signal to the wrapping tape portion of the 10 kV cable terminal to be evaluated and obtain the reflection coefficient curve of the reflected wave. The frequency band of the high-frequency microwave signal is 22 GHz to 30 GHz.

[0107] A reflection characteristic value selection module 202 is configured to select a preset number of minimum values ​​from the reflection coefficient curve as reflection characteristic values ​​to be evaluated, and select a corresponding defect-free reflection characteristic value based on the frequency of each reflection characteristic value to be evaluated;

[0108] The defect characteristic shift factor calculation module 203 is used to calculate the absolute value of the difference between each reflection characteristic value to be evaluated and each defect-free reflection characteristic value, and calculate the defect characteristic shift factor based on the absolute value of the difference;

[0109] The wrapping tape impurity defect assessment module 204 is used to calculate the wrapping tape impurity defect characterization parameters based on each reflection characteristic value to be assessed and the defect characteristic offset factor, and perform defect assessment on the wrapping tape portion of the cable terminal to be assessed using the wrapping tape impurity defect characterization parameters.

[0110] In one embodiment, the reflection coefficient curve acquisition module 201 includes:

[0111] The high-frequency microwave signal transmitting unit is used to transmit a high-frequency microwave signal to the 10kV cable terminal to be evaluated using a vector network analyzer, so that the high-frequency microwave signal is transmitted through the coaxial cable and the rectangular waveguide and then vertically enters the wrapping tape part of the cable terminal to be evaluated.

[0112] In one embodiment, the defect feature shift factor calculation module 203 includes:

[0113] The absolute value calculation unit is used to calculate the absolute value of the difference according to the following expression:

[0114]

[0115] in, Indicates the The absolute value of the difference, Indicates the The difference between the reflection characteristic value to be evaluated and its corresponding defect-free reflection characteristic value, Indicates the reflection eigenvalues ​​to be evaluated, Indicates the defect-free reflection characteristic values.

[0116] In one embodiment, the defect feature shift factor calculation module 203 includes:

[0117] The defect feature shift factor calculation unit is used to calculate the defect feature shift factor according to the following expression:

[0118]

[0119] in, represents the defect feature shift factor, Indicates the absolute value of the difference.

[0120] In one embodiment, the wrapping tape impurity defect assessment module 204 includes:

[0121] The wrapping tape impurity defect characterization parameter calculation unit is used to calculate the wrapping tape impurity defect characterization parameter according to the following expression:

[0122]

[0123] in, It represents the parameter characterizing the impurity defect of the wrapping tape. represents the defect feature shift factor, Indicates the The reflection eigenvalues ​​to be evaluated.

[0124] In one embodiment, the wrapping tape impurity defect assessment module 204 includes:

[0125] a first wrapping tape impurity defect assessment unit, configured to determine that the wrapping tape portion of the cable terminal to be assessed is free of impurities when a wrapping tape impurity defect characterization parameter is not greater than a first preset threshold;

[0126] a second wrapping tape impurity defect assessment unit, configured to determine that the wrapping tape portion of the cable terminal to be assessed contains dust impurities when a wrapping tape impurity defect characterization parameter is greater than a first preset threshold value and not greater than a second preset threshold value;

[0127] The third wrapping tape impurity defect evaluation unit is configured to determine that the wrapping tape portion of the cable terminal to be evaluated contains metal impurities when the wrapping tape impurity defect characterization parameter is greater than a second preset threshold.

[0128] In one embodiment, the first preset threshold is 3.817, and the second preset threshold is 5.639.

[0129] In one embodiment, the present application also provides a storage medium, which stores computer-readable instructions. When the computer-readable instructions are executed by one or more processors, the one or more processors execute the steps of the 10kV cable terminal wrapping tape impurity defect detection method as described in any of the above embodiments.

[0130] In one embodiment, the present application also provides a computer device, which stores computer-readable instructions. When the computer-readable instructions are executed by one or more processors, the one or more processors execute the steps of the 10kV cable terminal wrapping tape impurity defect detection method as described in any of the above embodiments.

[0131] Schematically, as Figure 3 As shown, Figure 3 This is a schematic diagram of the internal structure of a computer device provided in an embodiment of the present application. The computer device 300 can be provided as a server. Figure 3 Computer device 300 includes a processing component 302, which further includes one or more processors, and memory resources represented by memory 301 for storing instructions executable by processing component 302, such as application programs. The application programs stored in memory 301 may include one or more modules, each corresponding to a set of instructions. Furthermore, processing component 302 is configured to execute the instructions to perform the 10 kV cable terminal tape impurity defect detection method according to any of the aforementioned embodiments.

[0132] The computer device 300 may further include a power supply component 303 configured to perform power management of the computer device 300, a wired or wireless network interface 304 configured to connect the computer device 300 to a network, and an input / output (I / O) interface 305. The computer device 300 may operate based on an operating system stored in the memory 301, such as Windows Server™, Mac OS X™, Unix™, Linux™, Free BSD™, or the like.

[0133] Those skilled in the art will understand that Figure 3 The structure shown in the figure is only a block diagram of a part 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. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0134] Finally, it should be noted that, in this article, relational terms such as first and second are merely used to distinguish one entity or operation from another, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprise," "include," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. Without further restriction, an element defined by the phrase "comprising a..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element. Herein, "one," "said," "the," and "its" may also include plural forms unless the context clearly indicates otherwise. A plurality refers to at least two, such as 2, 3, 5, or 8. "And / or" includes any and all combinations of the relevant listed items.

[0135] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can be referenced to each other.

[0136] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for detecting impurity defects in 10kV cable terminal wrapping tape, characterized in that: The method comprises: A high-frequency microwave signal is emitted toward the wrapping tape of a 10 kV cable terminal to be evaluated, and a reflection coefficient curve of the reflected wave is obtained. The high-frequency microwave signal has a frequency range of 22 GHz to 30 GHz. Selecting a preset number of minimum values ​​from the reflection coefficient curve as reflection characteristic values ​​to be evaluated, and selecting a corresponding defect-free reflection characteristic value according to the frequency of each reflection characteristic value to be evaluated; Calculating a difference absolute value based on each of the reflection characteristic values ​​to be evaluated and each of the defect-free reflection characteristic values, and calculating a defect characteristic offset factor based on the difference absolute value; According to each of the reflection characteristic values ​​to be evaluated and the defect characteristic offset factor, a wrapping tape impurity defect characterization parameter is calculated, and a defect evaluation is performed on the wrapping tape portion of the cable terminal to be evaluated using the wrapping tape impurity defect characterization parameter.

2. The method for detecting impurity defects in 10kV cable terminal wrapping tape according to claim 1, characterized in that: The step of transmitting a high-frequency microwave signal to the wrapping tape portion of the 10 kV cable terminal to be evaluated comprises: A vector network analyzer is used to transmit the high-frequency microwave signal to the 10kV cable terminal to be evaluated, so that the high-frequency microwave signal is vertically injected into the wrapping tape portion of the cable terminal to be evaluated after being transmitted through the coaxial cable and the rectangular waveguide.

3. The method for detecting impurity defects in 10kV cable terminal wrapping tape according to claim 1, characterized in that: The step of calculating the absolute value of the difference based on each of the reflection characteristic values ​​to be evaluated and each of the defect-free reflection characteristic values ​​includes: The absolute value of the difference is calculated as follows: in, Indicates the The absolute value of the difference, Indicates the The difference between the reflection characteristic value to be evaluated and its corresponding defect-free reflection characteristic value, Indicates the the reflection characteristic value to be evaluated, Indicates the The defect-free reflection characteristic value.

4. The method for detecting impurity defects in 10kV cable terminal wrapping tape according to claim 1, characterized in that: The step of calculating the defect feature offset factor based on the absolute value of the difference includes: The defect characteristic shift factor is calculated as follows: in, represents the defect feature shift factor, represents the absolute value of the difference.

5. The method for detecting impurity defects in 10kV cable terminal wrapping tape according to claim 1, characterized in that: The step of calculating the impurity defect characterization parameter of the wrapping tape according to each of the reflection characteristic values ​​to be evaluated and the defect characteristic offset factor comprises: The impurity defect characterization parameter of the wrapping tape is calculated according to the following expression: in, represents the characterization parameter of the impurity defect of the wrapping tape, represents the defect feature shift factor, Indicates the The reflection characteristic value to be evaluated.

6. The method for detecting impurity defects in the 10kV cable terminal wrapping tape according to claim 1, characterized in that: The step of performing defect assessment on the wrapping tape portion of the cable terminal to be assessed using the wrapping tape impurity defect characterization parameter comprises: When the impurity defect characterization parameter of the wrapping tape is not greater than a first preset threshold value, the wrapping tape portion of the cable terminal to be evaluated is free of impurities; When the impurity defect characterization parameter of the wrapping tape is greater than the first preset threshold value and not greater than the second preset threshold value, the wrapping tape portion of the cable terminal to be evaluated contains dust impurities; When the wrapping tape impurity defect characterization parameter is greater than the second preset threshold, the wrapping tape portion of the cable terminal to be evaluated contains metal impurities.

7. The method for detecting impurity defects in the 10kV cable terminal wrapping tape according to claim 6, characterized in that: The first preset threshold is 3.817, and the second preset threshold is 5.

639.

8. A 10kV cable terminal wrapping tape impurity defect detection device, characterized in that: The device comprises: A reflection coefficient curve acquisition module is used to transmit a high-frequency microwave signal to the wrapping tape portion of the 10kV cable terminal to be evaluated and obtain a reflection coefficient curve of the reflected wave. The frequency band of the high-frequency microwave signal is 22GHz to 30GHz. a reflection characteristic value selection module, configured to select a preset number of minimum values ​​from the reflection coefficient curve as reflection characteristic values ​​to be evaluated, and select a corresponding defect-free reflection characteristic value based on the frequency of each reflection characteristic value to be evaluated; a defect characteristic shift factor calculation module, configured to calculate a difference absolute value between each of the reflection characteristic values ​​to be evaluated and each of the defect-free reflection characteristic values, and calculate a defect characteristic shift factor based on the difference absolute value; The wrapping tape impurity defect assessment module is used to calculate the wrapping tape impurity defect characterization parameter based on each of the reflection characteristic values ​​to be evaluated and the defect characteristic offset factor, and to perform defect assessment on the wrapping tape portion of the cable terminal to be evaluated using the wrapping tape impurity defect characterization parameter.

9. A storage medium, characterized in that: The storage medium stores computer-readable instructions, which, when executed by one or more processors, enable the one or more processors to perform the steps of the 10kV cable terminal wrapping tape impurity defect detection method as described in any one of claims 1 to 7.

10. A computer device, characterized in that: include: one or more processors, and memory; The memory stores computer-readable instructions, which, when executed by the one or more processors, execute the steps of the method for detecting impurity defects in the 10kV cable terminal wrapping tape as claimed in any one of claims 1 to 7.

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