A method, system, device and storage medium for detecting damage and damage size of cable copper shielding layer based on a combination of double frequency measurement method and step-by-step evaluation method

Abstract

The present invention discloses a method, system, device, and storage medium for detecting damage to the copper shielding layer of a cable and the size of the damage opening based on a combination of a double frequency measurement method and a step-by-step evaluation method. The method is applied to the technical field of power equipment status detection technology, comprising: obtaining measurement results of the cable under test under the injection of chirp signals with Gaussian envelopes of single and double center frequencies, and determining the start time of the injection signal and the arrival time of the reflected signal based on the extreme values ​​in the time-frequency cross-correlation curve; extracting the injection signal and the reflected signal using the start time and arrival time as the extraction starting points and the length of the injection signal as the extraction width, and calculating the damage degree based on the spectrum ratio of the reflected signal to the injection signal; calculating the characteristic impedance based on the damage degree, and sequentially determining the center angle and length of the damage opening of the cable copper shielding layer using a step-by-step evaluation method. The present invention realizes effective detection and positioning of copper shielding damage and effective estimation of the damage size.

Description

Technical Field

[0001] The present invention relates to the technical field of power equipment status detection, and in particular to a method, system, device and storage medium for detecting damage to a cable copper shielding layer and the size of a damaged opening based on a combination of a double frequency measurement method and a step-by-step evaluation method. Background Art

[0002] As the primary energy source in today's society, ensuring the safety and reliability of electricity supply is of paramount importance. Cables, as a crucial power transmission medium for power-consuming centers like cities and factories, are highly valued for their safety and reliability. However, due to manufacturing and processing issues, as well as environmental impacts during operation, cable copper shielding is prone to damage. Damage to the copper shielding can affect the uniform distribution of the electric field within the cable, accelerating cable aging and ultimately leading to cable failure and loss of power. Therefore, detecting copper shield damage is crucial during factory testing and routine maintenance of cable lines.

[0003] Existing methods for detecting copper shield damage in cable lines can be divided into reflectometer methods and partial discharge methods. The reflectometer method does not require applying voltage to the cable and is suitable for testing without power; the partial discharge test is suitable for testing cables while they are in operation. However, several problems still exist with existing detection methods. Time domain reflectometry is convenient and fast, but its sensitivity is low, making it prone to missed detections and unable to estimate the size of detected damage defects. Time-spectrum reflectometry (TFDR) has high sensitivity but is also unable to measure the size of the damage opening. The partial discharge method also suffers from the disadvantage of being unable to estimate the size of the defect. Without being able to estimate the size of the copper shield damage, it is impossible to determine the severity of the damage and, therefore, whether the cable requires repair.

[0004] To this end, how to provide a cable copper shielding damage and damage size detection method, system, equipment and storage medium based on the combination of double frequency measurement method and step-by-step evaluation method, which can effectively detect and locate the copper shielding damage of the cable line and effectively estimate the size of the copper shielding damage, so as to provide reference suggestions for whether subsequent repairs are needed. This is a problem that technical personnel in this field urgently need to solve. Summary of the Invention

[0005] In view of this, the present invention proposes a method, system, device and storage medium for detecting damage to the cable copper shielding layer and the size of the damaged opening based on a combination of a double frequency measurement method and a step-by-step evaluation method.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for detecting damage to a cable copper shield and the size of the damaged opening based on a combination of a double frequency measurement method and a step-by-step evaluation method, comprising:

[0008] Step 1: Obtain the measurement results of the cable under test under the injection of Gaussian envelope chirp signals at single and double the center frequency, and determine the start time of the injection signal and the arrival time of the reflected signal at single and double the center frequency based on the extreme values ​​in the time-frequency cross-correlation curve of the measurement results;

[0009] Step 2: Using the start time and arrival time as the extraction starting point and the length of the injection signal as the extraction width, extract the injection signal and reflection signal at single and double center frequencies. Calculate the cable copper shield damage at single and double center frequencies based on the spectrum ratio of the reflection signal to the injection signal.

[0010] Step 3: Based on the damage degree of the cable copper shielding layer at single and double center frequencies, calculate the characteristic impedance of the cable copper shielding layer damage defect, and use the step-by-step evaluation method to determine the central angle of the cable copper shielding layer damage opening under the characteristic impedance and the length of the damage opening under the cable copper shielding layer damage degree when the central angle is known.

[0011] Optionally, in step 1, when obtaining the measurement results of the cable under test under the injection of chirp signals with single and double center frequencies of Gaussian envelopes, the interval between the two measurements should be greater than twice the time required for the pulse to propagate from the first section of the cable to the end of the cable.

[0012] Optionally, in step 2, the cable copper shield damage at single and double center frequencies is calculated based on the spectrum ratio of the reflected signal to the injected signal, as follows:

[0013]

[0014] Among them, M r P is the damage degree of the cable copper shielding layer; sr is the spectrum ratio of the reflected signal to the injected signal; α p is the attenuation coefficient of the cable, which has different attenuation coefficients at different center frequencies; l a The distance between the defect head end and the signal injection point.

[0015] Optionally, the attenuation coefficient of the cable is calculated as follows:

[0016]

[0017] Among them, α p is the attenuation coefficient of the cable; l x The length of the known defect-free test cable of the same model as the cable to be tested; r(t) The injection signal of a defect-free test cable of known length and the same model as the cable to be tested at single and double center frequencies;r(t) The reflected signal of a defect-free test cable of known length and the same model as the cable to be tested at single and double center frequencies; Compute the spectrum for the Fourier transform.

[0018] Optionally, the distance between the defect head end and the signal injection point is calculated as follows:

[0019] l a =t d ·v p ;

[0020]

[0021] Among them, l a is the distance between the defect head end and the signal injection point; t d v is the time difference between the start time of the injection signal and the arrival time of the reflected signal at single center frequency of the cable under test; p is the wave velocity of the cable to be tested; l x The length of the known defect-free test cable of the same model as the cable to be tested; t x For a defect-free test cable of known length and the same model as the cable under test, when measuring an injection signal at single center frequency, determine the time difference between the arrival time of the reflected signal at the cable end and the start time of the injection signal based on the extreme value in the time-frequency cross-correlation curve of the measurement results.

[0022] Optionally, in step 3, based on the cable copper shield damage at single and double center frequencies, the characteristic impedance of the cable copper shield damage defect is calculated as follows:

[0023]

[0024] Among them, Z s is the characteristic impedance of the cable copper shielding layer damage defect; Z p is the characteristic impedance of the defect-free cable; Γ b is the reflection coefficient of the defect; M r1 M is the cable copper shield damage at single center frequency; r2 It is the cable copper shield damage degree at double the center frequency.

[0025] Optionally, in step 3, a step-by-step evaluation method is used to sequentially determine the central angle of the damaged opening of the cable copper shielding layer under characteristic impedance and the length of the damaged opening under the damage degree of the cable copper shielding layer when the central angle is known, specifically:

[0026] Construct a set of characteristic impedances of cable copper shield damage defects of different sizes and cable copper shield damage degrees;

[0027] By comparing the characteristic impedance of the copper shielding layer damage defect of the cable under test with the reference value, the central angle of the cable copper shielding layer damage opening under the characteristic impedance is obtained;

[0028] When the size of the central angle of the circle is known, the damage length of the cable copper shielding layer under the damage degree of the cable to be tested is obtained by comparing the damage degree of the cable copper shielding layer with the reference value.

[0029] The present invention also provides a cable copper shielding layer damage and damage opening size detection method based on a combination of a double frequency measurement method and a step-by-step evaluation method, comprising:

[0030] Time determination module: used to obtain the measurement results of the cable under test under the injection of Gaussian envelope chirp signals at single and double center frequencies, and determine the start time of the injection signal and the arrival time of the reflected signal at single and double center frequencies based on the extreme values ​​in the time-frequency cross-correlation curve of the measurement results;

[0031] Damage calculation module: The module uses the start time and arrival time as the extraction starting point and the length of the injection signal as the extraction width. It extracts the injection signal and the reflection signal at single and double center frequencies, and calculates the cable copper shield damage at single and double center frequencies based on the spectrum ratio of the reflection signal to the injection signal.

[0032] Damage opening size determination module: Based on the damage degree of the cable copper shielding layer at single and double center frequencies, the characteristic impedance of the cable copper shielding layer damage defect is calculated, and the central angle size of the cable copper shielding layer damage opening under the characteristic impedance is determined in sequence using a step-by-step evaluation method, as well as the damage opening length of the cable copper shielding layer under the damage degree when the central angle size is known.

[0033] The present invention further provides an electronic device, comprising:

[0034] memory for storing computer programs;

[0035] The processor is used to implement the steps of a method for detecting damage to the cable copper shielding layer and the size of the damaged opening based on a combination of a double frequency measurement method and a step-by-step evaluation method when executing a computer program.

[0036] The present invention also provides a computer-readable storage medium, characterized in that a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the steps of a method for detecting damage to the cable copper shielding layer and the size of the damaged opening are implemented based on a combination of a double frequency measurement method and a step-by-step evaluation method.

[0037] Through the above technical solution, it can be seen that compared with the existing technology, the present invention proposes a method, system, equipment and storage medium for detecting the damage and damage size of the cable copper shielding layer based on the combination of the double frequency measurement method and the step-by-step evaluation method. Based on the existing time-frequency domain reflectometer (TFDR) principle, by improving the measurement strategy of the traditional TFDR and introducing a new estimation method, the double frequency measurement method and the step-by-step estimation method are used to detect the damage of the cable copper shielding and measure the size of the copper shielding damage. This realizes the effective detection and positioning of the copper shielding damage of the cable line, as well as the effective estimation of the copper shielding damage size, providing reference suggestions for whether subsequent repairs are needed. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention 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 merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0039] Figure 1 Schematic diagram of the method of the present invention.

[0040] Figure 2 Schematic diagram of the reference value of characteristic impedance of the damaged copper shielded cable of the present invention.

[0041] Figure 3 Schematic diagram of the contour lines of the damage degree reference value of the present invention. DETAILED DESCRIPTION

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0043] Example 1:

[0044] Embodiment 1 of the present invention discloses a method for detecting damage to the copper shielding layer of a cable and the size of the damaged opening based on a combination of a double frequency measurement method and a step-by-step evaluation method, such as Figure 1 Shown, including:

[0045] Step 1: Obtain the measurement results of the cable under test under the injection of a chirp signal with a Gaussian envelope at single (first measurement) and double (second measurement) the center frequency. Based on the extreme values ​​in the time-frequency cross-correlation curve of the measurement results, determine the start time of the injection signal and the arrival time of the reflected signal at single and double the center frequency.

[0046] When obtaining the measurement results of the cable under test under the injection of chirp signals with a Gaussian envelope of single and double the center frequency, the interval between the two measurements should be greater than twice the time required for the pulse to propagate from the beginning of the cable to the end of the cable.

[0047] A time-frequency cross-correlation curve of the measurement results can be obtained according to a time-frequency cross-correlation method.

[0048] Step 2: Use the start time and arrival time as the extraction starting point, the length of the injection signal as the extraction width, extract the injection signal and reflection signal at single and double center frequencies, and calculate the cable copper shield damage at single and double center frequencies based on the spectrum ratio of the reflection signal to the injection signal.

[0049] The spectra of the reflected and injected signals can be obtained by Fourier transform.

[0050] According to the spectrum ratio of the reflected signal and the injected signal, the cable copper shield damage at single and double center frequencies is calculated as follows:

[0051]

[0052] Among them, M r P is the damage degree of the cable copper shielding layer; sr is the spectrum ratio of the reflected signal to the injected signal; α p is the attenuation coefficient of the cable, which has different attenuation coefficients at different center frequencies; l a The distance between the defect head end and the signal injection point.

[0053] The calculation method of the attenuation coefficient of the cable is as follows:

[0054]

[0055] Among them, α p is the attenuation coefficient of the cable; l x The length of the test cable with known length and no defects is required to be no less than 30m, and both ends of the cable line are open; r(t) The injection signal of a defect-free test cable of known length and the same model as the cable to be tested at single and double center frequencies; r(t)The reflected signal of a defect-free test cable of known length and the same model as the cable to be tested at single and double center frequencies; Compute the spectrum for the Fourier transform.

[0056] The distance between the first end of the defect and the signal injection point is calculated as follows:

[0057] l a =t d ·v p ;

[0058]

[0059] Among them, l a is the distance between the defect head end and the signal injection point; t d v is the time difference between the start time of the injection signal and the arrival time of the reflected signal at single center frequency of the cable under test; p is the wave velocity of the cable to be tested; l x The length of the known defect-free test cable of the same model as the cable to be tested; t x For a defect-free test cable of known length and the same model as the cable under test, when measuring an injection signal at single center frequency, determine the time difference between the arrival time of the reflected signal at the cable end and the start time of the injection signal based on the extreme value in the time-frequency cross-correlation curve of the measurement results.

[0060] Step 3: Based on the damage degree of the cable copper shielding layer at single and double center frequencies, calculate the characteristic impedance of the cable copper shielding layer damage defect, and use the step-by-step evaluation method to determine the central angle of the cable copper shielding layer damage opening under the characteristic impedance and the length of the damage opening under the cable copper shielding layer damage degree when the central angle is known, and finally realize the measurement of the damage opening size.

[0061] Based on the cable copper shield damage degree at single and double center frequencies, the characteristic impedance of the cable copper shield damage defect is calculated as follows:

[0062]

[0063] Among them, Z s is the characteristic impedance of the cable copper shielding layer damage defect; Z p is the characteristic impedance of the defect-free cable; Γ b is the reflection coefficient of the defect; M r1 M is the cable copper shield damage at single center frequency; r2 It is the cable copper shield damage degree at double the center frequency.

[0064] The step-by-step evaluation method is used to determine the central angle of the damaged opening of the cable copper shield under characteristic impedance and the length of the damaged opening under the damage degree of the cable copper shield when the central angle is known. Specifically:

[0065] A set of characteristic impedances and degrees of damage to the copper shielding layer of cables with different sizes of damage defects and cables with different sizes of damage defects is constructed, and the reference values ​​of the characteristic impedances and degrees of damage to the copper shielding layer of cables with different sizes of damage defects can be calculated by finite element method simulation.

[0066] By comparing the characteristic impedance of the copper shielding layer damage defect of the cable under test with the reference value, the central angle of the cable copper shielding layer damage opening under the characteristic impedance is obtained;

[0067] When the size of the central angle of the circle is known, the damage length of the cable copper shielding layer under the damage degree of the cable to be tested is obtained by comparing the damage degree of the cable copper shielding layer with the reference value.

[0068] Example 2:

[0069] Example 2 of the present invention discloses a specific application of a method for detecting damage to a cable copper shield layer and the size of a damaged opening based on a combination of a double frequency measurement method and a step-by-step evaluation method, as follows:

[0070] The cable model used is YJV-10kV single-core 35mm2. The length of the tested cable is 250m. The damage occurs at 50m. The central angle of the damage is 240° and the length of the damage is 0.5m.

[0071] In step 1, the duration of the chirp signal with a Gaussian envelope of single center frequency is 200 ns, the center frequency is 40 MHz, and the bandwidth is 40 MHz. The duration of the chirp signal with a Gaussian envelope of double center frequency is 200 ns, the center frequency is 80 MHz, and the bandwidth is 40 MHz. The interval between the two measurements is 0.5 s. The time-frequency cross-correlation method is used to calculate the time-frequency cross-correlation curve of the measured signal. Based on the maximum value in the curve, the time difference between the arrival time of the reflected signal and the start time of the injected pulse is calculated to be 0.592 μs.

[0072] In step 2: Use the attenuation coefficient calculation formula to calculate the attenuation coefficient α of the cable to be tested p At 40MHz (single center frequency), it is 0.001867m -1 , at 80MHz (double the center frequency) it is 0.002831m -1 According to the cable wave velocity calculation formula, the cable wave velocity is v pis 169m / s. Further, the distance l from the defect head end to the signal injection point is calculated according to the distance calculation formula from the defect head end to the signal injection point. a The distance from the measured point to the defect is 50.02m, while the actual defect location is 50m, resulting in a positioning error of 0.04%. Using the damage degree measurement formula, the damage degree at single center frequency is calculated to be 0.1236, and at double center frequency is 0.1613. Furthermore, using the characteristic impedance calculation formula for a cable copper shield damage defect, the characteristic impedance of the cable under test is calculated to be 47.67Ω.

[0073] In step 3: the characteristic impedance of the cable copper shielding layer damage defect and the reference value of the cable copper shielding layer damage degree under the cable copper shielding layer damage defects of different sizes are simulated by the finite element method, and the contour maps of the characteristic characteristic impedance reference value and the damage degree reference value are as follows: Figure 2 and Figure 3 As shown. Using the step-by-step estimation method, first compare Figure 2 , we can get the central angle of the damaged opening of the cable copper shielding layer is 236.86°. Further, when the central angle is 236.86°, we can compare Figure 3 , the estimated value of the damage opening length is 0.5035m. Comparing the actual and estimated values ​​of the central angle and damage opening length, the relative error of the central angle measurement is -1.31%, and the damage opening length is 0.7%, demonstrating the measurement accuracy and effectiveness of the present invention.

[0074] Example 3:

[0075] Embodiment 3 of the present invention discloses a cable copper shielding layer damage and damage opening size detection method based on a combination of a double frequency measurement method and a step-by-step evaluation method, comprising:

[0076] Time determination module: used to obtain the measurement results of the cable under test under the injection of Gaussian envelope chirp signals at single and double center frequencies, and determine the start time of the injection signal and the arrival time of the reflected signal at single and double center frequencies based on the extreme values ​​in the time-frequency cross-correlation curve of the measurement results;

[0077] Damage calculation module: The module uses the start time and arrival time as the extraction starting point and the length of the injection signal as the extraction width. It extracts the injection signal and the reflection signal at single and double center frequencies, and calculates the cable copper shield damage at single and double center frequencies based on the spectrum ratio of the reflection signal to the injection signal.

[0078] Damage opening size determination module: Based on the damage degree of the cable copper shielding layer at single and double center frequencies, the characteristic impedance of the cable copper shielding layer damage defect is calculated, and the central angle size of the cable copper shielding layer damage opening under the characteristic impedance is determined in sequence using a step-by-step evaluation method, as well as the damage opening length of the cable copper shielding layer under the damage degree when the central angle size is known.

[0079] Example 4:

[0080] Embodiment 4 of the present invention discloses an electronic device, including:

[0081] memory for storing computer programs;

[0082] The processor is used to implement the steps of a method for detecting damage to the cable copper shielding layer and the size of the damaged opening based on a combination of a double frequency measurement method and a step-by-step evaluation method when executing a computer program.

[0083] Example 5:

[0084] Embodiment 5 of the present invention discloses a computer-readable storage medium, characterized in that a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the steps of a method for detecting damage to the copper shielding layer of a cable and the size of the damaged opening are implemented based on a combination of a double frequency measurement method and a step-by-step evaluation method.

[0085] The embodiment of the present invention discloses a method, system, device and storage medium for detecting damage to the copper shielding layer of a cable and the size of the damage opening based on a combination of a double frequency measurement method and a step-by-step evaluation method. Based on the existing time-frequency domain reflectometer (TFDR) principle, by improving the measurement strategy of the traditional TFDR and introducing a new estimation method, the double frequency measurement method and the step-by-step estimation method are used to detect the damage to the copper shielding of the cable and measure the size of the copper shielding damage opening. This achieves effective detection and positioning of copper shielding damage in cable lines, as well as effective estimation of the size of copper shielding damage, providing reference suggestions for whether subsequent repairs are needed.

[0086] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0087] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. 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 invention. Therefore, the present invention 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 damage to the cable copper shielding layer and the size of the damaged opening based on a combination of a double frequency measurement method and a step-by-step evaluation method, characterized in that: include: Step 1: Obtain measurement results of the cable under test under the injection of Chirp signals with Gaussian envelopes at single and double center frequencies, respectively, and determine the start time of the injected signal and the arrival time of the reflected signal at single and double center frequencies based on the extreme values ​​in the time-frequency cross-correlation curve of the measurement results; Step 2: Taking the start time and the arrival time as the extraction starting point and the length of the injection signal as the extraction width, extract the injection signal and the reflection signal at the single and double center frequencies, and calculate the cable copper shielding layer damage at the single and double center frequencies according to the spectrum ratio of the reflection signal to the injection signal; Step 3: Based on the damage degree of the cable copper shielding layer at the single and double center frequencies, calculate the characteristic impedance of the cable copper shielding layer damage defect, and use a step-by-step evaluation method to determine the central angle size of the damaged opening of the cable copper shielding layer under the characteristic impedance and the length of the damaged opening under the damage degree of the cable copper shielding layer when the central angle size is known.

2. The method for detecting damage to the cable copper shielding layer and the size of the damaged opening based on the combination of the double frequency measurement method and the step-by-step evaluation method according to claim 1 is characterized in that: In step 1, when obtaining the measurement results of the cable under test under the injection of Chirp signals with single and double center frequencies of Gaussian envelope, the interval between the two measurements should be greater than twice the time required for the pulse to propagate from the first section of the cable to the end of the cable.

3. The method for detecting damage to the cable copper shielding layer and the size of the damaged opening based on the combination of the double frequency measurement method and the step-by-step evaluation method according to claim 1 is characterized in that: In step 2, the cable copper shielding layer damage at the single and double center frequencies is calculated based on the spectrum ratio of the reflected signal to the injected signal, as follows: Among them, M r P is the damage degree of the cable copper shielding layer; sr is the spectrum ratio of the reflected signal to the injected signal; α p is the attenuation coefficient of the cable, which has different attenuation coefficients at different center frequencies; l a The distance between the defect head end and the signal injection point.

4. The method for detecting damage to the cable copper shielding layer and the size of the damaged opening based on the combination of the double frequency measurement method and the step-by-step evaluation method according to claim 3 is characterized in that: The calculation method of the attenuation coefficient of the cable is as follows: Among them, α p is the attenuation coefficient of the cable; l x The length of the known defect-free test cable of the same model as the cable to be tested; r(t) is the injection signal of a defect-free test cable of known length and the same model as the cable to be tested at the single and double center frequencies; r r(t) The reflected signal of a defect-free test cable of known length and the same model as the cable to be tested at the single and double center frequencies; Compute the spectrum for the Fourier transform.

5. The method for detecting damage to the cable copper shielding layer and the size of the damaged opening based on the combination of the double frequency measurement method and the step-by-step evaluation method according to claim 3 is characterized in that: The method for calculating the distance between the defect head end and the signal injection point is as follows: l a =t d ·v p ; Among them, l a is the distance between the defect head end and the signal injection point; t d v is the time difference between the start time of the injection signal and the arrival time of the reflected signal at single center frequency of the cable under test; p is the wave velocity of the cable to be tested; l x The length of the known defect-free test cable of the same model as the cable to be tested; t x For a defect-free test cable of known length and the same model as the cable under test, when measuring an injection signal at single center frequency, determine the time difference between the arrival time of the reflected signal at the cable end and the start time of the injection signal based on the extreme value in the time-frequency cross-correlation curve of the measurement results.

6. The method for detecting damage to the cable copper shielding layer and the size of the damaged opening based on the combination of the double frequency measurement method and the step-by-step evaluation method according to claim 1 is characterized in that: In step 3, based on the damage degree of the cable copper shielding layer at the single and double center frequencies, the characteristic impedance of the cable copper shielding layer damage defect is calculated as follows: Among them, Z s is the characteristic impedance of the cable copper shielding layer damage defect; Z p is the characteristic impedance of the defect-free cable; Γ b is the reflection coefficient of the defect; M r1 M is the cable copper shield damage at single center frequency; r2 It is the cable copper shield damage degree at double the center frequency.

7. The method for detecting damage to the cable copper shielding layer and the size of the damaged opening based on the combination of the double frequency measurement method and the step-by-step evaluation method according to claim 1 is characterized in that: In step 3, a step-by-step evaluation method is used to sequentially determine the central angle of the damaged opening of the cable copper shielding layer under the characteristic impedance and the length of the damaged opening under the damage degree of the cable copper shielding layer when the central angle is known, specifically: Construct a set of cable copper shield damage defects of different sizes, characteristic impedances of cable copper shield damage defects, and cable copper shield damage degrees; By comparing the characteristic impedance of the cable copper shielding layer damage defect of the cable to be tested with a reference value, the central angle of the cable copper shielding layer damage opening under the characteristic impedance is obtained; When the size of the central angle is known, the damage length of the cable copper shielding layer under the damage degree of the cable to be tested is obtained by comparing the damage degree of the cable copper shielding layer with a reference value.

8. A cable copper shielding layer damage and damage opening size detection method based on a combination of a double frequency measurement method and a step-by-step evaluation method according to any one of claims 1 to 7, characterized in that: include: Time determination module: used to obtain the measurement results of the cable under test under the injection of Chirp signals with Gaussian envelopes at single and double center frequencies, and determine the start time of the injection signal and the arrival time of the reflected signal at single and double center frequencies according to the extreme values ​​in the time-frequency cross-correlation curve of the measurement results; A damage degree calculation module is configured to extract the injection signal and the reflected signal at the single and double center frequencies using the start time and the arrival time as extraction starting points, and the length of the injection signal as the extraction width. The module also calculates the damage degree of the cable copper shielding layer at the single and double center frequencies based on the spectrum ratio of the reflected signal to the injection signal. Damage opening size determination module: Based on the damage degree of the cable copper shielding layer at the single and double center frequencies, the characteristic impedance of the cable copper shielding layer damage defect is calculated, and a step-by-step evaluation method is used to sequentially determine the central angle size of the damage opening of the cable copper shielding layer under the characteristic impedance and the damage opening length of the cable copper shielding layer under the damage degree when the central angle size is known.

9. An electronic device, characterized in that: include: memory for storing computer programs; A processor, configured to implement, when executing the computer program, the steps of a method for detecting damage to the cable copper shielding layer and the size of the damaged opening based on a combination of a double frequency measurement method and a step-by-step evaluation method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of a method for detecting damage to the cable copper shielding layer and the size of the damaged opening based on a combination of a double frequency measurement method and a step-by-step evaluation method as described in any one of claims 1 to 7.

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