Cable defect diagnosis method and device based on pulse frequency domain reflection and medium

Abstract

The embodiment of the invention discloses a cable defect diagnosis method and equipment based on pulse frequency domain reflection and a medium, relates to the field of cable defect detection, and is used for overcoming the defects of an existing time domain reflection method and an existing frequency domain reflection method. The method comprises the following steps: injecting a trapezoidal pulse signal into the head end of a to-be-detected cable, performing time domain segmentation on a measurement signal according to the total duration of an incident signal, and separating the incident signal from a reflected signal; obtaining an effective frequency band range of the trapezoidal pulse signal, and obtaining frequency domain expressions of the separated incident signal and the reflected signal; intercepting an effective frequency band range corresponding to the frequency domain expressions of the separated incident signal and the reflected signal according to the effective frequency band range of the trapezoidal pulse signal, so as to determine a head end reflection coefficient spectrum of the cable to be detected according to the intercepted frequency domain incident signal and frequency domain reflected signal; performing spectrum analysis on the head end reflection coefficient spectrum to obtain a cable defect diagnosis function, and judging the defect of the to-be-detected cable according to the cable defect diagnosis function.

Description

Technical Field

[0001] This specification relates to the technical field of cable defect location, and in particular to a cable defect diagnosis method, device, and medium based on pulse frequency domain reflection. Background Art

[0002] In modern industrial systems, cables serve as the core carriers of information and energy transmission, and their reliability has a direct and critical impact on system performance. Under the long-term influence of complex operating conditions such as heat, electricity, and radiation, cables are prone to localized insulation degradation. If these defects are not discovered and addressed promptly, they can rapidly develop into serious failures, posing a significant threat to the safe and stable operation of industrial systems.

[0003] Currently, traveling wave reflectometry is a commonly used method for cable inspection in practical engineering applications, primarily including time-domain reflectometry and frequency-domain reflectometry. The time-domain reflectometry method offers advantages such as a simple and easy-to-understand principle, compact equipment, and rapid detection speed. However, due to the severe attenuation of the reflected traveling wave's head during transmission and the low high-frequency component of the detection signal, this method exhibits suboptimal accuracy and sensitivity in locating cable defects. In contrast, the frequency-domain reflectometry method, which includes abundant high-frequency components and utilizes transfer functions to invert the reflected signal, exhibits superior positioning accuracy and sensitivity. However, the frequency-domain reflectometry method exhibits high requirements for detection equipment, resulting in relatively high equipment costs and a long detection time, which limits its practical application. Summary of the Invention

[0004] In order to solve the above technical problems, one or more embodiments of this specification provide a cable defect diagnosis method, device and medium based on pulse frequency domain reflection.

[0005] One or more embodiments of this specification adopt the following technical solutions:

[0006] One or more embodiments of this specification provide a cable defect diagnosis method based on pulse frequency domain reflection, the method comprising:

[0007] Injecting a trapezoidal pulse signal into the head end of the cable to be detected, so as to perform time domain segmentation on the measurement signal of the head end of the cable to be detected according to the total duration of the incident signal, and separate the incident signal and the reflected signal of the cable to be detected;

[0008] Obtaining an effective frequency band range of the trapezoidal pulse signal, and performing discrete Fourier transform on the separated incident signal and reflected signal to obtain frequency domain expressions of the separated incident signal and reflected signal;

[0009] The effective frequency band range corresponding to the frequency domain expressions of the separated incident signal and reflected signal is intercepted according to the effective frequency band range of the trapezoidal pulse signal, so as to determine the head-end reflection coefficient spectrum of the cable to be detected according to the intercepted frequency domain incident signal and frequency domain reflected signal;

[0010] A spectrum analysis is performed on the head-end reflection coefficient spectrum to obtain a cable defect diagnosis function, and defects of the cable to be detected are determined according to the cable defect diagnosis function.

[0011] Optionally, in one or more embodiments of the present specification, a trapezoidal pulse signal is injected into the head end of the cable to be detected, so as to perform time domain segmentation on the measurement signal of the head end of the cable to be detected according to the total duration of the incident signal, thereby separating the incident signal and the reflected signal of the cable to be detected, specifically including:

[0012] A preset pulse signal generator generates a trapezoidal pulse signal corresponding to a preset signal expression and injects it into the head end of the cable to be tested; wherein the preset signal expression is:

[0013] A is the amplitude of the trapezoidal pulse signal; τ r is the rise time; τ p is the pulse width; τ f is the fall time;

[0014] determining a total duration of the incident signal based on the rise time, the pulse width, and the fall time;

[0015] Taking the start time of the trapezoidal pulse signal injected into the head end of the cable to be detected as time zero, determining the time interval corresponding to the incident signal and the reflected signal according to the time zero and the total duration;

[0016] According to the time mark corresponding to the measurement signal of the head end of the cable to be detected and the corresponding time interval, the measurement signal of the head end of the cable to be detected is divided in time domain to separate the incident signal and the reflected signal of the cable to be detected.

[0017] Optionally, in one or more embodiments of this specification, obtaining the effective frequency band range of the trapezoidal pulse signal specifically includes:

[0018] Performing spectrum analysis on the trapezoidal pulse signal to obtain a spectrum amplitude corresponding to the trapezoidal pulse signal;

[0019] Obtaining the frequency corresponding to the maximum value within the spectrum amplitude and the first minimum value point within the spectrum amplitude;

[0020] The preset ratio of the maximum value is taken as the upper limit of the effective frequency band of the trapezoidal pulse signal, and the upper limit of the effective frequency band does not exceed the frequency corresponding to the first minimum point; wherein, the preset ratio is 5%.

[0021] Optionally, in one or more embodiments of the present specification, performing discrete Fourier transform on the separated incident signal and reflected signal to obtain frequency domain expressions of the separated incident signal and reflected signal specifically includes:

[0022] The separated incident signal is subjected to a discrete Fourier transform to obtain an incident signal frequency domain sequence as the frequency domain expression of the separated incident signal; wherein the incident signal frequency domain sequence is: U t is the frequency domain sequence of the incident signal; u t is the time domain sequence of the incident signal; k is the frequency domain sequence index; n is the time domain sequence index; N is the number of sequences;

[0023] The separated reflected signal is subjected to a discrete Fourier transform to obtain a reflected signal frequency domain sequence as the frequency domain expression of the separated reflected signal; wherein the incident signal frequency domain sequence is: U r is the frequency domain sequence of the reflected signal; u r is the reflected signal frequency domain.

[0024] Optionally, in one or more embodiments of this specification, after performing discrete Fourier transform on the separated incident signal and reflected signal to obtain frequency domain expressions of the separated incident signal and reflected signal, the method further includes:

[0025] Based on the frequency domain sequence formula, the frequency domain expression of the separated incident signal and the frequency domain expression of the separated reflected signal are respectively established as indexes between corresponding frequency values; wherein the frequency domain sequence formula is: f is the frequency sequence; T s is the signal sampling rate.

[0026] Optionally, in one or more embodiments of the present specification, the effective frequency band corresponding to the frequency domain expression of the separated incident signal and reflected signal is intercepted according to the effective frequency band of the trapezoidal pulse signal, so as to determine the head-end reflection coefficient spectrum of the cable to be detected according to the intercepted frequency domain incident signal and frequency domain reflected signal, specifically including:

[0027] According to the effective frequency band range of the trapezoidal pulse signal, the effective frequency band range corresponding to the frequency domain expression of the separated incident signal and reflected signal is intercepted to obtain the intercepted frequency domain incident signal and frequency domain reflected signal;

[0028] Based on the ratio of the frequency domain incident signal to the frequency domain reflected signal, the head-end reflection coefficient spectrum of the cable to be detected is determined; wherein the head-end reflection coefficient spectrum is M is the effective upper band index.

[0029] Optionally, in one or more embodiments of this specification, performing spectrum analysis on the head-end reflection coefficient spectrum to obtain a cable defect diagnosis function specifically includes:

[0030] Obtaining construction elements of a cable defect diagnosis function by performing spectrum analysis on the head-end reflection coefficient spectrum;

[0031] The construction elements are processed based on a weighted summation method to construct the cable defect diagnosis function; wherein the cable defect diagnosis function is:

[0032] x is the distance from the cable head end; C is the Chebyshev window function; Δf is the frequency interval, l is the cable length, and β is the phase constant.

[0033] Optionally, in one or more embodiments of the present specification, determining the defect of the cable to be detected according to the cable defect diagnosis function specifically includes:

[0034] The cable defect location function and the cable defect polarity function are constructed based on the cable defect diagnosis function; wherein the cable defect location function is D loc (x)=|D(x)|, the cable defect polarity function is D pol (x) = real(D(x)), where real represents the real part;

[0035] Determining the defect position of the cable to be detected by using a cable defect location function, and substituting the defect position into the cable defect polarity function to determine the defect polarity of the cable to be detected;

[0036] Defect determination of the cable to be inspected is achieved based on the defect position and the defect polarity.

[0037] One or more embodiments of this specification provide a cable defect diagnosis device based on pulse frequency domain reflection, the device comprising:

[0038] at least one processor; and,

[0039] a memory communicatively connected to the at least one processor; wherein,

[0040] The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to: perform any of the above methods.

[0041] One or more embodiments of this specification provide a non-volatile computer storage medium storing computer-executable instructions, wherein the computer-executable instructions are configured to execute any of the above-described methods.

[0042] At least one of the above technical solutions adopted in the embodiments of this specification can achieve the following beneficial effects:

[0043] A trapezoidal pulse signal is used as the measurement signal to be injected into the head end of the cable to be tested. The short duration of the trapezoidal pulse signal is effectively utilized, so that the diagnostic process does not require the use of complex devices such as power splitters and directional couplers to separate the incident and reflected signals. At the same time, a small amount of data is required, which is conducive to lightweight and rapid cable defect detection. The signal is processed in the time domain, frequency domain, and invalid frequency band, which effectively reduces the impact of noise and interference on the detection results. The frequency domain reflection method avoids the positioning error caused by the distortion of the reflected signal wave head during time domain reflection detection, which is conducive to the accurate detection of cable defects. In addition, in the diagnostic process, the mismatch of the cable head will not introduce the head end shielding area in the diagnostic results. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are only some of the embodiments described in this specification. For those skilled in the art, other drawings can be obtained based on these drawings without inventive work. In the drawings:

[0045] Figure 1 A schematic diagram of a method flow of a cable defect diagnosis method based on pulse frequency domain reflection provided in an embodiment of this specification;

[0046] Figure 2 A schematic diagram of a defective cable in an application scenario provided by an embodiment of this specification;

[0047] Figure 3 A schematic diagram of the experimental principle of a defective cable in an application scenario provided in an embodiment of this specification;

[0048] Figure 4 A defect diagnosis diagram provided in an embodiment of this specification, in which the reflection coefficient spectrum band is consistent with the effective frequency band;

[0049] Figure 5 A defect diagnosis diagram provided in an embodiment of this specification, wherein the reflection coefficient spectrum band is smaller than the effective frequency band;

[0050] Figure 6A defect diagnosis diagram provided in an embodiment of this specification, wherein the reflection coefficient spectrum band is larger than the effective frequency band;

[0051] Figure 7 A schematic diagram of the structure of a cable defect diagnosis device based on pulse frequency domain reflection provided in an embodiment of this specification;

[0052] Figure 8 A schematic diagram of the structure of a non-volatile storage medium provided in an embodiment of this specification. DETAILED DESCRIPTION

[0053] The embodiments of this specification provide a cable defect diagnosis method, device, and medium based on pulse frequency domain reflection.

[0054] To help those skilled in the art better understand the technical solutions in this specification, the following will provide a clear and complete description of the technical solutions in the embodiments of this specification, in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of this specification, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this specification without creative work should fall within the scope of protection of this specification.

[0055] like Figure 1 As shown, the embodiment of this specification provides a method flow chart of a cable defect diagnosis method based on pulse frequency domain reflection. Figure 1 It can be seen that in one or more embodiments of this specification, a cable defect diagnosis method based on pulse frequency domain reflection includes the following steps:

[0056] S101: injecting a trapezoidal pulse signal into the head end of a cable to be detected, so as to perform time domain segmentation on a measurement signal at the head end of the cable to be detected according to the total duration of the incident signal, and separate the incident signal and the reflected signal of the cable to be detected.

[0057] The traditional frequency domain reflection method will inject all the frequency points into the head end of the cable to be detected at once, resulting in the signal entering the head end of the cable to be detected being a continuous and very long signal. This causes the incident signal and the reflected signal in the cable to be detected to be mixed together. Therefore, the traditional frequency domain reflection method requires a power divider and a directional coupler to separate the incident and reflected signals, which is difficult to analyze directly. Therefore, in order to overcome this problem and avoid the problem of the signal duration being too long, in the embodiment of this specification, a trapezoidal pulse signal is injected into the head end of the cable to be detected, and then the measurement signal of the head end of the cable to be detected is time-domain segmented according to the total duration of the incident signal to separate the incident signal and the reflected signal of the cable to be detected. In this process, the signal injected into the head end of the cable to be detected is a trapezoidal pulse signal. Due to the short duration of the trapezoidal pulse signal, the problem of the existing need for complex devices such as power dividers and directional couplers to distinguish between the incident and reflected signals is solved. At the same time, due to the short duration of the signal, a small amount of data is required, which is conducive to the lightweight and rapid detection of cable defects.

[0058] Specifically, in one or more embodiments of the present specification, a trapezoidal pulse signal is injected into the head end of the cable to be detected, so as to perform time domain segmentation on the measurement signal of the head end of the cable to be detected according to the total duration of the incident signal, thereby separating the incident signal and the reflected signal of the cable to be detected. Specifically, the process includes the following:

[0059] First, based on Figure 3 The preset pulse signal generator shown generates a trapezoidal pulse signal corresponding to the preset signal expression and injects it into the head end of the cable to be tested; wherein the preset signal expression is:

[0060] A is the amplitude of the trapezoidal pulse signal; τ r is the rise time; τ p is the pulse width; τ f is the fall time. Then the total duration of the incident signal is determined based on the rise time, pulse width and fall time. Figure 2 The diagram of a defective cable provided in this manual is shown below. The cable model is RG58, the length is 100m, and a parallel defect (negative polarity) is set at 40m: Z sh =50Ω, a series defect positive polarity is set at 70m: Z se =50Ω, cable end open circuit: Z L =∞. The parameters of the trapezoidal pulse injected into the cable head end are: amplitude of 5V, signal rise time, pulse width, and fall time are 10ns respectively.

[0061] The start time of the trapezoidal pulse signal injected into the head end of the cable to be tested is defined as time zero. The time intervals corresponding to the incident and reflected signals are determined based on time zero and the total duration. Based on the time stamps and time intervals corresponding to the measurement signal at the head end of the cable to be tested, the measurement signal at the head end of the cable to be tested is time-domain segmented to separate the incident and reflected signals.

[0062] This process uses a preset pulse signal generator to generate a specific trapezoidal pulse signal. It eliminates the need for power splitters and directional couplers to separate the incident and reflected signals, placing low demands on equipment, reducing both size and weight, and facilitating lightweight cable defect detection. By performing time-domain segmentation on the incident and reflected signals, and accurately determining the time intervals and matching the segmentation based on the time stamps of the measured signals, the incident and reflected signals can be precisely separated. This avoids signal mixing and interference, making subsequent analysis more accurate. Furthermore, compared to traditional time-domain reflectometry, which suffers from positioning errors caused by distortion of the reflected signal's wave head, this process's pulse frequency-domain reflectometry avoids this problem, facilitating more accurate cable defect detection.

[0063] S102: Acquire the effective frequency band range of the trapezoidal pulse signal, and perform discrete Fourier transform on the separated incident signal and reflected signal to obtain frequency domain expressions of the separated incident signal and reflected signal.

[0064] Specifically, in one or more embodiments of this specification, obtaining the effective frequency band range of the trapezoidal pulse signal specifically includes:

[0065] Perform spectrum analysis on the trapezoidal pulse signal to obtain the spectrum amplitude corresponding to the trapezoidal pulse signal, and then determine the maximum value within the spectrum amplitude and the frequency corresponding to the first minimum point within the spectrum amplitude, so as to determine the effective frequency band upper limit of the trapezoidal pulse signal based on the maximum value and the preset ratio, and the effective frequency band upper limit does not exceed the frequency corresponding to the first minimum point; it should be noted that the preset ratio is 5%.

[0066] Specifically, to avoid the problem of severe head attenuation of the reflected traveling wave in the current time domain reflectometry and the low high-frequency component of the detection signal, which results in low positioning accuracy and sensitivity of the time domain reflectometry, in one or more embodiments of this specification, a discrete Fourier transform is performed on the separated incident signal and reflected signal to obtain a frequency domain representation of the separated incident signal and reflected signal, specifically including the following process:

[0067] The separated incident signal is subjected to discrete Fourier transform to obtain the incident signal frequency domain sequence, which is used as the frequency domain expression of the separated incident signal. Among them, the incident signal frequency domain sequence is:

[0068] Ut is the frequency domain sequence of the incident signal; u t is the time domain sequence of the incident signal; k is the frequency domain sequence index; n is the time domain sequence index; N is the number of sequences;

[0069] At the same time, the separated reflected signal is subjected to discrete Fourier transform to obtain the reflected signal frequency domain sequence, which is used as the frequency domain expression of the separated reflected signal. Among them, the incident signal frequency domain sequence is:

[0070] U r is the frequency domain sequence of the reflected signal; u r Further, in one or more embodiments of the present specification, after performing discrete Fourier transform on the separated incident signal and reflected signal to obtain the frequency domain representation of the separated incident signal and reflected signal, the method further includes:

[0071] Based on the frequency domain sequence formula, the frequency domain expression of the separated incident signal and the frequency domain expression of the separated reflected signal are respectively indexed between the corresponding frequency values; wherein, the frequency domain sequence formula is:

[0072] f is the frequency sequence; T s is the signal sampling rate.

[0073] S103: intercepting the effective frequency band range corresponding to the frequency domain expression of the separated incident signal and reflected signal according to the effective frequency band range of the trapezoidal pulse signal, so as to determine the head-end reflection coefficient spectrum of the cable to be detected according to the intercepted frequency domain incident signal and frequency domain reflected signal.

[0074] Specifically, in one or more embodiments of the present specification, the effective frequency band corresponding to the frequency domain expressions of the separated incident signal and reflected signal is intercepted according to the effective frequency band of the trapezoidal pulse signal, so as to determine the head-end reflection coefficient spectrum of the cable to be detected according to the intercepted frequency domain incident signal and frequency domain reflected signal, which specifically includes:

[0075] First, the invalid frequency band of the incident signal and the reflected signal is cut off. That is, the effective frequency band corresponding to the frequency domain expression of the separated incident signal and reflected signal is cut off according to the effective frequency band of the trapezoidal pulse signal to obtain the cut-off frequency domain incident signal and frequency domain reflected signal. Then, based on the ratio of the frequency domain incident signal to the frequency domain reflected signal, the head-end reflection coefficient spectrum of the cable to be tested is determined; wherein the head-end reflection coefficient spectrum is:

[0076] M is the upper limit index of the effective frequency band. Figure 4As shown in Figure 2, when the frequency band of the reflection coefficient spectrum is consistent with the effective frequency band proposed by this method, the defect can be accurately located at 40.09m and 70.15m, and the polarity of the defect can be easily determined by the discrete determination method. Figure 5 and Figure 6 As shown, when the frequency band of the reflection coefficient spectrum is inconsistent with the effective frequency band, the positioning results will show significant broadening or oscillation. This shows that by cutting off the invalid frequency band in this process, the defect determination process can focus on the frequency information valuable for defect diagnosis and avoid interference from the invalid frequency band. Furthermore, after eliminating the invalid frequency band interference, the stability of the reflection coefficient spectrum is improved, which can reduce the influence of external factors on the detection results, making the reflection coefficient spectrum more stable, providing a reliable basis for accurate defect judgment and reducing misjudgments.

[0077] S104: performing spectrum analysis on the head-end reflection coefficient spectrum to obtain a cable defect diagnosis function, and determining defects of the cable to be detected according to the cable defect diagnosis function.

[0078] After obtaining the head-end reflection coefficient spectrum in step S103, in embodiments of this specification, a spectral analysis is performed on the head-end reflection coefficient spectrum to obtain a cable defect diagnosis function corresponding to the cable to be inspected, so that defects in the cable to be inspected can be determined based on the cable defect diagnosis function. Specifically, in one or more embodiments of this specification, the spectral analysis is performed on the head-end reflection coefficient spectrum to obtain the cable defect diagnosis function, which specifically includes the following process:

[0079] First, by performing spectral analysis on the head-end reflection coefficient spectrum, the building blocks of the cable defect diagnosis function are obtained. Then, the building blocks are processed based on a weighted summation method to construct a cable defect diagnosis function; wherein, the cable defect diagnosis function is:

[0080] x is the distance from the cable head end; C is the Chebyshev window function; Δf is the frequency interval, l is the cable length, and β is the phase constant.

[0081] Specifically, in one or more embodiments of this specification, determining defects of a cable to be detected according to a cable defect diagnosis function specifically includes the following process:

[0082] The cable defect location function and the cable defect polarity function are constructed based on the cable defect diagnosis function; wherein the cable defect location function is D loc (x)=|D(x)|, the cable defect polarity function is D pol(x) = real(D(x)), where real represents the real part. The defect location and polarity are then determined separately based on the cable defect location function and the cable defect polarity function. That is, the defect location of the cable to be tested is determined using the cable defect location function, and the defect location is substituted into the cable defect polarity function to determine the defect polarity of the cable to be tested. Based on the defect location and polarity, the defect of the cable to be tested is determined. And if Figure 4 The above method does not introduce a head-end shielding area into the diagnosis result when the head end of the cable is mismatched, thus avoiding the shielding area problem of the traditional frequency domain reflection method.

[0083] like Figure 7 As shown in FIG, the embodiment of this specification provides a schematic diagram of the structure of a cable defect diagnosis device based on pulse frequency domain reflection. Figure 7 It can be seen that in one or more embodiments of this specification, a pulse frequency domain reflectometry cable defect diagnosis device includes:

[0084] at least one processor; and,

[0085] a memory communicatively connected to the at least one processor; wherein,

[0086] The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to: perform any of the above methods.

[0087] like Figure 8 As shown in FIG, the embodiment of this specification provides a structural diagram of a non-volatile storage medium. Figure 8 As shown, in one or more embodiments of this specification, a non-volatile storage medium stores computer-executable instructions, and the computer-executable instructions can: execute any of the methods described above.

[0088] The various embodiments in this specification are described in a progressive manner. Similar portions between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from the other embodiments. In particular, the device, apparatus, and non-volatile computer storage medium embodiments are generally similar to the method embodiments, so their descriptions are relatively simplified. For relevant details, refer to the descriptions of the method embodiments.

[0089] The foregoing description of this specification describes specific embodiments. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be performed in an order different from that described in the embodiments and still achieve the desired results. Furthermore, the processes depicted in the accompanying drawings do not necessarily require the specific order shown or the sequential order to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0090] The foregoing description is merely one or more embodiments of this specification and is not intended to limit this specification. It will be apparent to those skilled in the art that various modifications and variations may be made to one or more embodiments of this specification. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of one or more embodiments of this specification are intended to be within the scope of the claims of this specification.

Claims

1. A cable defect diagnosis method based on pulse frequency domain reflection, characterized in that: The method comprises: Injecting a trapezoidal pulse signal into the head end of the cable to be detected, so as to perform time domain segmentation on the measurement signal of the head end of the cable to be detected according to the total duration of the incident signal, and separate the incident signal and the reflected signal of the cable to be detected; Obtaining an effective frequency band range of the trapezoidal pulse signal, and performing discrete Fourier transform on the separated incident signal and reflected signal to obtain frequency domain expressions of the separated incident signal and reflected signal; The effective frequency band range corresponding to the frequency domain expressions of the separated incident signal and reflected signal is intercepted according to the effective frequency band range of the trapezoidal pulse signal, so as to determine the head-end reflection coefficient spectrum of the cable to be detected according to the intercepted frequency domain incident signal and frequency domain reflected signal; A spectrum analysis is performed on the head-end reflection coefficient spectrum to obtain a cable defect diagnosis function, and defects of the cable to be detected are determined according to the cable defect diagnosis function.

2. The cable defect diagnosis method based on pulse frequency domain reflection according to claim 1 is characterized in that: Injecting a trapezoidal pulse signal into the head end of the cable to be detected to perform time domain segmentation on the measurement signal at the head end of the cable to be detected according to the total duration of the incident signal, thereby separating the incident signal and the reflected signal of the cable to be detected, specifically comprising: A preset pulse signal generator generates a trapezoidal pulse signal corresponding to a preset signal expression and injects it into the head end of the cable to be tested; wherein the preset signal expression is: A is the amplitude of the trapezoidal pulse signal; τ r is the rise time; τ p is the pulse width; τ f is the fall time; determining a total duration of the incident signal based on the rise time, the pulse width, and the fall time; Taking the start time of the trapezoidal pulse signal injected into the head end of the cable to be detected as time zero, determining the time interval corresponding to the incident signal and the reflected signal according to the time zero and the total duration; According to the time mark corresponding to the measurement signal of the head end of the cable to be detected and the corresponding time interval, the measurement signal of the head end of the cable to be detected is divided in time domain to separate the incident signal and the reflected signal of the cable to be detected.

3. The cable defect diagnosis method based on pulse frequency domain reflection according to claim 1, characterized in that: Obtaining the effective frequency band range of the trapezoidal pulse signal specifically includes: Performing spectrum analysis on the trapezoidal pulse signal to obtain a spectrum amplitude corresponding to the trapezoidal pulse signal; Obtaining the frequency corresponding to the maximum value within the spectrum amplitude and the first minimum value point within the spectrum amplitude; The preset ratio of the maximum value is taken as the upper limit of the effective frequency band of the trapezoidal pulse signal, and the upper limit of the effective frequency band does not exceed the frequency corresponding to the first minimum point; wherein, the preset ratio is 5%.

4. The cable defect diagnosis method based on pulse frequency domain reflection according to claim 1, characterized in that: The separated incident signal and reflected signal are subjected to discrete Fourier transform to obtain the frequency domain representation of the separated incident signal and reflected signal, which specifically includes: The separated incident signal is subjected to a discrete Fourier transform to obtain an incident signal frequency domain sequence as the frequency domain expression of the separated incident signal; wherein the incident signal frequency domain sequence is: U t is the frequency domain sequence of the incident signal; u t is the time domain sequence of the incident signal; k is the frequency domain sequence index; n is the time domain sequence index; N is the number of sequences; The separated reflected signal is subjected to discrete Fourier transform to obtain a reflected signal frequency domain sequence as the frequency domain expression of the separated reflected signal; wherein the incident signal frequency domain sequence is: U r is the frequency domain sequence of the reflected signal; u r is the reflected signal frequency domain.

5. The cable defect diagnosis method based on pulse frequency domain reflection according to claim 1, characterized in that: After performing discrete Fourier transform on the separated incident signal and reflected signal to obtain frequency domain expressions of the separated incident signal and reflected signal, the method further includes: Based on the frequency domain sequence formula, the frequency domain expression of the separated incident signal and the frequency domain expression of the separated reflected signal are respectively established as indexes between corresponding frequency values; wherein the frequency domain sequence formula is: f is the frequency sequence; T s is the signal sampling rate.

6. The cable defect diagnosis method based on pulse frequency domain reflection according to claim 4 is characterized in that: The effective frequency band range corresponding to the frequency domain expression of the separated incident signal and reflected signal is intercepted according to the effective frequency band range of the trapezoidal pulse signal, so as to determine the head end reflection coefficient spectrum of the cable to be detected according to the intercepted frequency domain incident signal and frequency domain reflected signal, specifically including: According to the effective frequency band range of the trapezoidal pulse signal, the effective frequency band range corresponding to the frequency domain expression of the separated incident signal and reflected signal is intercepted to obtain the intercepted frequency domain incident signal and frequency domain reflected signal; Based on the ratio of the frequency domain incident signal to the frequency domain reflected signal, the head-end reflection coefficient spectrum of the cable to be detected is determined; wherein the head-end reflection coefficient spectrum is M is the effective upper band index.

7. The cable defect diagnosis method based on pulse frequency domain reflection according to claim 5, characterized in that: Performing spectrum analysis on the head-end reflection coefficient spectrum to obtain a cable defect diagnosis function specifically includes: Obtaining construction elements of a cable defect diagnosis function by performing spectrum analysis on the head-end reflection coefficient spectrum; The construction elements are processed based on a weighted summation method to construct the cable defect diagnosis function; wherein the cable defect diagnosis function is: x is the distance from the cable head end; C is the Chebyshev window function; Δf is the frequency interval, l is the cable length, and β is the phase constant.

8. The cable defect diagnosis method based on pulse frequency domain reflection according to claim 1, characterized in that: Determining the defects of the cable to be detected according to the cable defect diagnosis function specifically includes: The cable defect location function and the cable defect polarity function are constructed based on the cable defect diagnosis function; wherein the cable defect location function is D loc (x)=|D(x)|, the cable defect polarity function is D pol (x) = real(D(x)), where real represents the real part; Determining the defect position of the cable to be detected by using a cable defect location function, and substituting the defect position into the cable defect polarity function to determine the defect polarity of the cable to be detected; Defect determination of the cable to be inspected is achieved based on the defect position and the defect polarity.

9. A cable defect diagnosis device based on pulse frequency domain reflection, characterized in that: The device comprises: at least one processor; and, a memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to: execute the method according to any one of claims 1 to 8.

10. A non-volatile storage medium storing computer-executable instructions, characterized in that: The computer executable instructions can execute the method according to any one of claims 1 to 8.

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