Method and system for improving cable defect positioning accuracy based on beat signal phase information

Abstract

The application discloses a cable defect positioning precision improvement method and system based on beat signal phase information, belongs to the technical field of cable defect positioning, and comprises the following steps: acquiring a beat signal containing cable defect position information, and performing normalization to obtain a normalized beat signal; decomposing the normalized beat signal to obtain two beat signal subsequences; performing DFT on the beat signal subsequences after zero padding to obtain DFT discrete point numbers corresponding to beat signal subsequence amplitude spectrum peak values; calculating phase differences at the DFT discrete point numbers corresponding to the beat signal subsequence amplitude spectrum peak values; and correcting a defect positioning result based on DFT by using the phase differences. The application effectively improves the ranging precision of a DFT-based cable defect positioning method.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of cable defect positioning, and relates to a cable defect positioning precision improvement method, in particular to a cable defect positioning precision improvement method and system based on beat signal phase information. BACKGROUND

[0002] Power cables are gradually becoming the main part of urban power transmission and distribution networks due to their small footprint and high reliability. However, permanent faults often occur in running cables, which may cause damage to electrical equipment and even lead to power outages, resulting in serious economic losses and social impacts. Permanent faults in cables usually start from local defects, and if these defects are not timely and effectively eliminated, they will pose a significant threat to the safe and stable operation of the power system. Therefore, it is of great significance to accurately locate the local defects in the cable.

[0003] At present, the cable defect positioning method mainly uses the traveling wave method. Among them, the frequency domain reflection method is widely used due to its high sensitivity in defect detection. This method injects a series of sweep signals into the cable head, obtains the input impedance spectrum or reflection coefficient spectrum of the cable, and uses mathematical methods such as Discrete Fourier Transform (DFT) to convert the frequency domain data to the spatial domain, thereby realizing the positioning of the cable defects. However, the frequency domain reflection method is easily disturbed by field noise, and the positioning accuracy of local defects still needs to be further improved in actual application. Although there are studies that use zero padding method to improve distance measurement accuracy, this method has certain limitations. Specifically, when the distance measurement accuracy is doubled, the number of DFT points also needs to be doubled, resulting in a significant increase in computational load. The number of spectral lines within the main lobe of the defect positioning peak increases, making it more difficult to determine the maximum amplitude spectral line. In addition, the interference of field noise limits the improvement effect of distance measurement accuracy. SUMMARY

[0004] The purpose of the present application is to provide a cable defect positioning precision improvement method and system based on beat signal phase information to solve the problem of low positioning accuracy in traditional frequency domain reflection method in cable local defect detection.

[0005] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0006] The cable defect positioning precision improvement method based on beat signal phase information comprises the following steps:

[0007] Obtain the beat signal containing the cable defect position information and normalize it to obtain the normalized beat signal;

[0008] Decompose the normalized beat signal to obtain two beat signal subsequences;

[0009] After zero padding the beat signal subsequences, DFT is performed to obtain the DFT discrete point number corresponding to the amplitude spectrum peak value of the beat signal subsequences;

[0010] The phase difference at the DFT discrete point number corresponding to the amplitude spectrum peak value of the beat signal subsequences is calculated;

[0011] The defect positioning result based on DFT is corrected by using the phase difference.

[0012] Further, the beat signal is obtained, specifically:

[0013] The sawtooth wave modulation mode is used for the frequency-modulated continuous wave voltage signal as the incident signal for positioning the cable defects. In a modulation period, the instantaneous frequency f(t) of the incident signal is:

[0014] f(t)=f0+St

[0015] In the formula, f0 is the initial frequency; S=B / T is the frequency modulation slope, B is the frequency modulation bandwidth, and T is the frequency modulation period;

[0016] The incident signal T(t) is:

[0017]

[0018] In the formula, A is the effective value of the incident signal;

[0019] The incident signal is reflected at the impedance discontinuity point in the cable. By using the phasor method, the reflected signal R(t) detected at the signal injection end is:

[0020]

[0021] In the formula, l is the actual distance from the impedance discontinuity point to the signal injection end; p l is the reflection coefficient at the impedance discontinuity point, p l =(Z s -Z0) / (Z s +Z0), where Z s is the characteristic impedance at the impedance discontinuity point, Z0 is the characteristic impedance of the healthy line segment; a is the attenuation constant; and t is the time delay of the reflected signal relative to the incident signal, t=2l / v, where v is the average propagation speed of the signal in the cable;

[0022] After the incident signal and the reflected signal are mixed, the beat signal s(t) is obtained, which is expressed as:

[0023]

[0024] Further, the normalized beat signal s(n) is expressed as:

[0025]

[0026] wherein N is the number of sampling points in a modulation period, Δt = T / N is the sampling interval, and the sampling frequency is f s = 1 / Δt = N / T.

[0027] Further, the normalized beat signal is decomposed to obtain two beat signal subsequences, specifically:

[0028] The normalized beat signal s(n) is decomposed into two subsequences, wherein the first N1 points of s(n) constitute a first subsequence s1(n), and the last N1 points of s(n) constitute a second subsequence s2(n). The first subsequence s1(n) and the second subsequence s2(n) can partially overlap, i.e., 2N1≥N.

[0029]

[0030] Further, the beat signal subsequences are zero-padded and then subjected to DFT, specifically:

[0031] The zero-padded sequence s 1e (n) of the first subsequence s1(n) is:

[0032]

[0033] wherein M is the length of the zero-padded sequence, and M > N1.

[0034] The M-point DFT of s 1e (n) is:

[0035]

[0036] The zero-padded sequence s 2e (n) of the second subsequence s2(n) is:

[0037]

[0038] The M-point DFT of s 2e (n) is:

[0039]

[0040] The DFT discrete points corresponding to the amplitude spectrum peaks of s1(k) and s2(k) in [0, M-1] are the same, and are denoted as k1.

[0041]

[0042] In the formula, round[x] represents the integer closest to x; ΔR is the distance resolution unit; ΔR1 is the distance resolution unit corresponding to the M-point DFT;

[0043]

[0044] Further, the phase difference of the peak value of the amplitude spectrum of the beat signal subsequence corresponding to the number of DFT discrete points is calculated, specifically:

[0045] The phases of s1(k) and s2(k) are different, and at the discrete frequency corresponding to k1, the phases of s1(k1) and s2(k1) are respectively denoted as and are represented as follows:

[0046]

[0047] The phase difference between the two is:

[0048]

[0049] Using The distance of the cable defect is accurately measured within a distance resolution unit ΔR1.

[0050] Further, the phase difference is used to correct the DFT-based defect positioning result, specifically:

[0051] Within a distance resolution unit ΔR1, the correction amount of the distance of the cable defect is calculated as:

[0052]

[0053] Let The defect distance calculated from the discrete spectrum of the subsequence is:

[0054]

[0055] The distance of the cable defect from the signal injection end is calculated as:

[0056]

[0057] The cable defect positioning precision improvement system based on beat signal phase information includes:

[0058] A signal acquisition module is configured to acquire a beat signal containing cable defect position information, normalize the beat signal, and obtain a normalized beat signal.

[0059] A decomposition module is configured to decompose the normalized beat signal to obtain two beat signal subsequences.

[0060] DFT module: used for DFT of the beat signal subsequence after zero padding, to obtain the DFT discrete point number corresponding to the beat signal subsequence amplitude spectrum peak value;

[0061] Calculation module: used for calculating the phase difference at the DFT discrete point number corresponding to the beat signal subsequence amplitude spectrum peak value;

[0062] Correction module: used for correcting the DFT-based defect positioning result by using the phase difference.

[0063] A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method for improving the cable defect positioning precision based on the beat signal phase information.

[0064] A computer readable storage medium, which stores a computer program, wherein the computer program is executable by a processor to implement the steps of the method for improving the cable defect positioning precision based on the beat signal phase information.

[0065] Compared with the prior art, the present application has the following beneficial technical effects:

[0066] The method of the present application decomposes the sampling sequence of the beat signal into two sub-sequences, and performs DFT on each sub-sequence after zero padding to improve the frequency measurement precision of the sub-sequences; the phase difference at the DFT discrete point number corresponding to the DFT amplitude spectrum peak value of the sub-sequences is used to calculate the correction amount of the defect distance within one distance resolution unit. The phase difference of the sub-sequences can effectively solve the whole cycle ambiguity problem in phase measurement, and can correct the defect distance measurement error caused by the DFT fence effect, and correct the defect positioning result within one distance resolution unit. BRIEF DESCRIPTION OF DRAWINGS

[0067] The accompanying drawings are included to provide a further understanding of the present application, and are incorporated in and constitute a part of this application. The schematic embodiments of the present application and their descriptions serve to explain the present application, and do not constitute an improper limitation on the present application.

[0068] Figure 1 DFT-based cable defect positioning result;

[0069] Figure 2 DFT amplitude spectrum of the first sub-sequence of the beat signal;

[0070] Figure 3 DFT partial phase spectrum of the first sub-sequence of the beat signal;

[0071] Figure 4 DFT amplitude spectrum of the second sub-sequence of the beat signal;

[0072] Figure 5 DFT part phase spectrum of the second sub-sequence of the beat signal;

[0073] Figure 6 Flowchart of the cable defect positioning precision improvement method based on beat signal phase information of the present application;

[0074] Figure 7 Structural diagram of the cable defect positioning precision improvement system based on beat signal phase information of the present application. DETAILED DESCRIPTION

[0075] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should fall within the scope of protection of the present application.

[0076] It should be noted that the terms "first", "second", and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device that includes a series of steps or units does not have to be limited to only those steps or units clearly listed, but can include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0077] Embodiment one

[0078] Referring to Figure 6 , the cable defect positioning precision improvement method based on beat signal phase information of the present application comprises the following steps:

[0079] Obtain the beat signal containing cable defect position information and normalize it to obtain the normalized beat signal;

[0080] Decompose the normalized beat signal to obtain two beat signal sub-sequences;

[0081] After zero padding the beat signal sub-sequences, perform DFT to obtain the DFT discrete point number corresponding to the amplitude spectrum peak value of the beat signal sub-sequences;

[0082] Calculate the phase difference at the DFT discrete point number corresponding to the amplitude spectrum peak value of the beat signal sub-sequences;

[0083] The phase difference is used to correct the DFT-based defect positioning result.

[0084] The method of the application decomposes the sampling sequence of the beat signal into two sub-sequences, and performs DFT on each sub-sequence after zero padding to improve the frequency measurement accuracy of the sub-sequences; the phase difference at the DFT discrete point corresponding to the peak value of the DFT amplitude spectrum of the sub-sequences is used to calculate the correction amount of the defect distance within one distance resolution unit, and the method can correct the defect distance measurement error caused by the DFT fence effect, and effectively improve the distance measurement accuracy of the DFT-based cable defect positioning method.

[0085] Embodiment two

[0086] The application provides a cable defect positioning accuracy improvement method based on beat signal phase information, comprising:

[0087] (1) obtaining a beat signal

[0088] The application uses a sawtooth wave modulation method of a frequency-modulated continuous wave voltage signal as an incident signal for positioning cable defects. In one modulation period, the instantaneous frequency f(t) of the incident signal is:

[0089] f(t)=f0+St

[0090] In the formula, f0 is the initial frequency; S=B / T is the frequency modulation slope, B is the frequency modulation bandwidth, and T is the frequency modulation period.

[0091] The incident signal T(t) is:

[0092]

[0093] In the formula, A is the effective value of the incident signal.

[0094] The incident signal is reflected at the impedance discontinuity point in the cable, and the reflected signal R(t) detected at the signal injection end is derived using the phasor method:

[0095]

[0096] In the formula, l is the actual distance from the impedance discontinuity point to the signal injection end; ρ l is the reflection coefficient at the impedance discontinuity point, ρ l =(Z s -Z0) / (Z s +Z0), where Z s is the characteristic impedance at the impedance discontinuity point, Z0 is the characteristic impedance of the healthy line segment; α is the attenuation constant; τ is the time delay of the reflected signal relative to the incident signal, τ=2l / v, where v is the average propagation speed of the signal in the cable.

[0097] The incident and reflected signals, after being mixed, yield a beat signal s(t), which can be expressed as:

[0098]

[0099] To simplify subsequent calculations, the amplitude of the beat signal is normalized, resulting in:

[0100]

[0101] In practical applications, beat signals are typically sampled, and then the sampled sequence is subjected to a Directed Fourier Transform (DFT) to locate cable defects. Assume the number of sampling points within one modulation period is N, the sampling interval is Δt = T / N, and the sampling frequency is f. s =1 / Δt = N / T. The normalized beat signal s(n) after sampling is:

[0102]

[0103] (2) Decompose the beat signal

[0104] The sampled beat signal s(n) is decomposed into two subsequences. The first N1 points of s(n) constitute the first subsequence s1(n), and the last N1 points of s(n) constitute the second subsequence s2(n). The subsequences s1(n) and s2(n) can partially overlap, i.e., 2N1≥N.

[0105]

[0106] (3) Perform DFT after zero-padding the beat signal subsequence.

[0107] The sequence s1(n) after zero-padding 1e (n) is:

[0108]

[0109] In the formula, M is the length of the zero-padded sequence, and M>N1.

[0110] s 1e The M-point DFT of (n) is:

[0111]

[0112] The sequence s2(n) after zero-padding 2e (n) is:

[0113]

[0114] s 2e The M-point DFT of (n) is:

[0115]

[0116] s1(k) and s2(k) have the same DFT discrete point number corresponding to the amplitude spectrum peak value in [0, M-1], denoted as k1, and have:

[0117]

[0118] where round[x] represents the integer closest to x; ΔR is the distance resolution unit; and ΔR1 is the distance resolution unit corresponding to the M-point DFT.

[0119]

[0120] (4) Calculate the phase difference at the DFT discrete point number corresponding to the amplitude spectrum peak value of the beat signal subsequence

[0121] The phases of s1(k) and s2(k) are different, and at the discrete frequency corresponding to k1, the phases of s1(k1) and s2(k1) are denoted as and have:

[0122]

[0123] The phase difference between the two is:

[0124]

[0125] changes linearly with distance, as long as N, N1, and M are appropriately selected, The change within one distance resolution unit ΔR1 will not exceed 2π, that is, The measurement of can more accurately measure the distance of the cable defect within one distance resolution unit ΔR1.

[0126] (5) Correct the defect positioning result

[0127] Within one distance resolution unit ΔR1, the correction amount of the cable defect distance can be calculated as:

[0128]

[0129] Let be the defect distance calculated from the discrete spectrum of the subsequence, and have:

[0130]

[0131] Then, the distance of the cable defect position from the signal injection end can be calculated as:

[0132]

[0133] Embodiment three

[0134] Based on the MATLAB simulation platform, a 1500m 330kV single-core cable is simulated, a 500Ω high resistance grounding occurs at a distance of 500m from the signal injection end, the incident signal amplitude is 2.5V, f0=0.5MHz, B=10MHz, T=1ms, N=10000, N1=5000, M=20000, to illustrate the effectiveness of the defect positioning precision improvement method based on the phase information of the beat signal.

[0135] The cable defect positioning result based on the original sampling sequence of the beat signal is as shown in Figure 1 , the discrete frequency corresponding to the maximum of the defect characteristic peak in the spectrum amplitude is 52, and the defect distance is calculated as 506.01m, and the positioning relative error is 1.2%.

[0136] The original sampling sequence of the beat signal is split, the first 5000 points of the beat signal constitute a first sub-sequence, and the last 5000 points of the beat signal constitute a second sub-sequence. The first sub-sequence is zero-padded and subjected to 20000-point DFT, and the amplitude spectrum simulation result is as shown in Figure 2 , and the phase spectrum part simulation result is as shown in Figure 3 . The second sub-sequence is also zero-padded and subjected to 20000-point DFT, and the amplitude spectrum simulation result is as shown in Figure 4 , and the phase spectrum part simulation result is as shown in Figure 5 .

[0137] In the amplitude spectrum of the first sub-sequence and the second sub-sequence, the discrete frequency corresponding to the maximum of the defect characteristic peak in the spectrum amplitude is the same, both being 102. The phase corresponding to the discrete frequency 102 of the first sub-sequence is-2.95668 rad, and the phase corresponding to the discrete frequency 102 of the second sub-sequence is-0.92748 rad, the corrected cable defect distance is 500.565m, and the positioning relative error is 0.11%. Therefore, compared with the cable defect positioning method based on DFT, the method provided by the application can effectively improve the cable defect positioning precision.

[0138] Embodiment four

[0139] Referring to Figure 7 , the application provides a cable defect positioning precision improvement system based on the phase information of the beat signal, comprising:

[0140] A signal acquisition module is used to acquire a beat signal containing cable defect position information, and to normalize the beat signal to obtain a normalized beat signal.

[0141] Decomposition module: used for decomposing the normalized beat signal to obtain two beat signal subsequences;

[0142] DFT module: used for performing DFT on the beat signal subsequences after zero padding to obtain DFT discrete point numbers corresponding to the amplitude spectrum peak values of the beat signal subsequences;

[0143] Calculation module: used for calculating the phase difference at the DFT discrete point numbers corresponding to the amplitude spectrum peak values of the beat signal subsequences;

[0144] Correction module: used for correcting the DFT-based defect positioning result by using the phase difference.

[0145] Embodiment five

[0146] The present application provides a kind of computer equipment, including memory, processor and the computer program stored in the memory and can be run on the processor, when the processor executes the computer program, the steps of the method for improving the positioning accuracy of cable defect based on beat signal phase information are realized.

[0147] Embodiment six

[0148] The present application provides a kind of computer readable storage medium, the computer readable storage medium stores computer program, characterized in that, when the computer program is executed by processor, the steps of the method for improving the positioning accuracy of cable defect based on beat signal phase information are realized.

[0149] Those skilled in the art will appreciate that embodiments of the present application can be provided as methods, systems, or computer program products. Accordingly, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage media, etc.) having computer usable program code embodied therein.

[0150] The present application is described with reference to flowcharts and / or block diagrams of the method, device (system), and computer program product according to embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, as well as combinations of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing apparatus to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing apparatus produce a device that implements the functions specified in the flowcharts and / or block diagrams. Figure 1 The device that implements the functions specified in one flow or multiple flows and / or blocks Figure 1 The device that implements the functions specified in one flow or multiple flows and / or blocks

[0151] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the flow Figure 1 one or more flow or block Figure 1 one or more blocks or blocks specified in the flow.

[0152] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions executed on the computer or other programmable apparatus provide steps for implementing the flow Figure 1 one or more flow or block Figure 1 one or more blocks or blocks specified in the flow.

[0153] Finally, it should be noted that the above examples are merely used to illustrate the technical solutions of the present application, but not to limit the protection scope thereof. Although the present application has been described in detail with reference to the above examples, those skilled in the art should understand that, after reading the present application, they can make various changes, modifications or equivalent replacements to the specific embodiments of the present application. However, these changes, modifications or equivalent replacements are all within the protection scope of the claims of the present application.

Claims

1. A method for improving the accuracy of cable defect location based on beat signal phase information, characterized in that, The method comprises the following steps: obtaining beat signal containing cable defect position information, and performing normalization to obtain normalized beat signal; decomposing the normalized beat signal to obtain two beat signal subsequences; Specifically: normalizing the beat signal s ( n ) into two subsequences, s ( n ) the first subsequence N 1 s 1( n ) of the first s 1 n 2 N 2( s ) of the second n 2 s 1 n 1( s ) and the second subsequence n 2 N 1 ≥ N ; wherein is the initial frequency, B is the frequency modulation bandwidth, is the time delay of the reflected signal relative to the incident signal, = 2 l / v , v is the average propagation speed of the signal in the cable, l is the actual distance from the impedance discontinuity to the signal injection point, N is the number of sampling points within the modulation period; performing DFT on the beat signal subsequences after zero padding to obtain DFT discrete point numbers corresponding to amplitude spectrum peak values of the beat signal subsequences; calculating phase difference at the DFT discrete point numbers corresponding to the amplitude spectrum peak values of the beat signal subsequences; correcting defect positioning result based on DFT by using the phase difference.

2. The method for improving the precision of locating the defects in the cable based on the phase information of the beat signal according to claim 1, characterized in that, The beat signal is obtained, and specifically: The sawtooth wave modulation mode is adopted for the frequency-modulated continuous wave voltage signal as the incident signal for locating the defects of the cable, and the instantaneous frequency of the incident signal in a modulation period is: f ( t ) wherein is the initial frequency; S = B / T is the frequency modulation slope, B is the frequency modulation bandwidth, T is the frequency modulation period; incident signal T ( t ) is: wherein A is the effective value of the incident signal; The reflected signal detected at the signal injection end is derived using the phasor method R ( t ) is: wherein l is the actual distance from the impedance discontinuity to the signal injection point; is the reflection coefficient at the impedance discontinuity, = ( Z s - Z 0) / ( Z s + Z 0), wherein Z s is the characteristic impedance at the impedance discontinuity, Z 0 is the characteristic impedance of the healthy line section; is the attenuation constant; is the time delay of the reflected signal relative to the incident signal, =2 l / v , wherein v is the average propagation speed of the signal in the cable; The incident signal and the reflected signal are mixed to obtain beat signals s t are represented as​ 。 3. The method for improving the precision of cable defect location based on beat signal phase information according to claim 2, characterized in that, The normalized beat signal s ( n ) is expressed as: In the formula, N is the number of sampling points in the modulation period, is the sampling interval, and the sampling frequency is .

4. The method for improving the precision of locating the defects in the cable based on the phase information of the beat signal according to claim 1, characterized in that, the beat signal subsequences are subjected to DFT after zero padding, and specifically: The first sub-sequence s 1( n ) The sequence after zero padding s 1e ( n ) is: In the formula, M is the length of the sequence after zero padding, M < / s> N 1; s 1e n ) of the present application M Point DFT is:​ The second sub-sequence s 2( n ) the sequence after zero padding s 2e ( n ) is: s 2e ( n ) of the M point DFT is: s 1( k )and s 2( k ) in [0, M The number of DFT discrete points corresponding to the peak values ​​of the inner amplitude spectrum is the same, denoted as: k 1: where round[ ] denotes taking the integer closest to x x is the distance resolution cell; is the M distance resolution cell corresponding to the point DFT.​​ 。 5. The method for improving the accuracy of locating a cable defect based on beat signal phase information according to claim 4, characterized in that, the phase difference at the DFT discrete point numbers corresponding to the amplitude spectrum peak values of the beat signal subsequences is calculated, and specifically: s 1( k ) and s 2( k ) are different, at the discrete frequency corresponding to k 1, s 1( k 1) and s 2( k 1) are denoted as and respectively, and are expressed as follows: the phase difference between the two is: Utilizing In one distance resolution unit Cable defect distance is accurately measured within.

6. The method for improving the accuracy of locating a cable defect based on beat signal phase information according to claim 5, wherein, the defect positioning result based on DFT is corrected by using the phase difference, and specifically: In one distance resolution unit The distance resolution unit calculates the distance correction amount of the cable defect as Let For the defect distance calculated from the discrete spectrum of the subsequence, we have: the distance of the cable defect position from the signal injection end is calculated as: 。 7. A system for improving the accuracy of cable defect location based on beat signal phase information, characterized in that, comprises: a signal acquisition module: used for obtaining beat signal containing cable defect position information, and performing normalization to obtain normalized beat signal; a decomposition module: used for decomposing the normalized beat signal to obtain two beat signal subsequences; Specifically: Normalized beat signal s ( n It can be decomposed into two subsequences, where, s ( n (before) N One point constitutes the first subsequence s 1( n ), s ( n ) after N One point constitutes the second subsequence s 2( n ), the first subsequence s 1( n ) and the second subsequence s 2( n ) can partially overlap, i.e., 2 N 1≥ N ; wherein f 0 is the initial frequency, B is the frequency modulation bandwidth, is the time delay of the reflected signal relative to the incident signal, = 2 l v v is the average propagation speed of the signal in the cable, l is the actual distance from the impedance discontinuity to the signal injection point, N is the number of sampling points within the modulation period;​​ a DFT module: used for performing DFT on the beat signal subsequences after zero padding to obtain DFT discrete point numbers corresponding to amplitude spectrum peak values of the beat signal subsequences; a calculation module: used for calculating phase difference at the DFT discrete point numbers corresponding to the amplitude spectrum peak values of the beat signal subsequences; a correction module: used for correcting defect positioning result based on DFT by using the phase difference.

8. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, The processor executes the computer program to realize the steps of the cable defect positioning precision improvement method based on beat signal phase information according to any one of claims 1 to 6.

9. A computer-readable storage medium storing a computer program, the computer program comprising instructions that, when executed by a computer, cause the computer to perform the method of any one of claims 1 to 8. The computer program is executed by the processor to realize the steps of the cable defect positioning precision improvement method based on beat signal phase information according to any one of claims 1 to 6.

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