A method, device, and medium for cable defect location interference peak suppression

Abstract

The embodiment of the application discloses a cable defect positioning interference peak suppression method, device and medium, and belongs to the technical field of cable defect detection. The embodiment solves the problem of low accuracy of cable defect positioning detection in the prior art. The obtained first-end frequency domain reflection coefficient data of the to-be-tested cable is subjected to positioning conversion processing to obtain an original positioning curve of the to-be-tested cable. Based on the number of positioning peaks, the first-end frequency domain reflection coefficient data of the to-be-tested cable is subjected to variational mode decomposition processing to obtain a plurality of frequency components. Based on frequency decreasing order, the plurality of frequency components are matched with the plurality of positioning peaks. Based on the matching result, the first interference frequency component corresponding to the to-be-tested cable is removed. The correlation coefficients between the remaining frequency components and preset frequency components are determined, and based on the correlation coefficients, the second interference frequency component corresponding to the to-be-tested cable is removed. The remaining frequency components are subjected to reflection coefficient spectrum reconstruction to obtain a cable positioning curve after interference peaks are suppressed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cable defect detection, and in particular to a cable defect positioning interference peak suppression method, device and medium. BACKGROUND

[0002] Cables are widely used in modern power systems due to their environmental friendliness, high safety and stability. Cable-based urban power grids will be an important development trend in the future. However, due to wear and tear during installation and laying, various stresses, high temperature and humidity, and acidic or alkaline environments, cables are prone to partial damage, thermal aging, moisture aging and other local defects. If not timely located and repaired, it will affect the safety and stability of the entire power system, and may cause equipment damage, production interruption and personal injury. Therefore, timely diagnosis and positioning of cable defects are of great significance for accurately understanding the health status of cables and maintaining the stable operation of power systems.

[0003] Frequency Domain Reflectometry (FDR) based on Reflection Coefficient Spectrum (RCS) is a fast, effective and non-destructive method for cable defect positioning. This method injects a swept signal into the cable head, measures the reflection coefficient spectrum data, and then processes these data through a series of algorithms to convert the frequency domain data into spatial domain data, thereby realizing the positioning of local defects. FDR can detect and locate local weak defects and non-discharge defects, and has significant technical advantages.

[0004] However, in field tests, due to the impedance mismatch between the characteristic impedance of the measured cable and the signal connection line of the FDR test equipment, the test signal is folded and reflected at the impedance mismatch point, which will cause a positioning peak to appear at the position of the cable head in the positioning map, which is easy to be misjudged as a defect, resulting in the cable head becoming a blind area for defect positioning. In addition, due to the multiple folding and reflection of the test signal in the measured cable in a very short time, these multiple reflection signals are collected by the test equipment, which will cause a false peak to appear in the positioning map, and the position corresponding to the false peak has no local defect, which interferes with the judgment of the field test, resulting in a low accuracy of cable defect positioning detection. SUMMARY

[0005] The embodiments of the present application provide a cable defect positioning interference peak suppression method, device and medium, which are used to solve the technical problem that the existing positioning map has a blind area for defect positioning and a false peak, which interferes with the judgment of the field test, resulting in a low accuracy of cable defect positioning detection.

[0006] The embodiments of the present application adopt the following technical solutions:

[0007] The embodiment of the application provides a cable defect positioning interference peak suppression method, including: performing positioning conversion processing on the obtained first-end frequency domain reflection coefficient data of a to-be-tested cable to obtain an original positioning curve of the to-be-tested cable; determining the number of positioning peaks corresponding to the original positioning curve of the to-be-tested cable, and performing variational mode decomposition processing on the first-end frequency domain reflection coefficient data of the to-be-tested cable based on the number of positioning peaks to obtain a plurality of frequency components; matching the plurality of frequency components with a plurality of positioning peaks based on frequency descending order; removing the first-end frequency component corresponding to the to-be-tested cable based on the matching result; determining the correlation coefficients between the remaining frequency components and preset frequency components, and removing the second-end frequency component corresponding to the to-be-tested cable based on the correlation coefficients; and performing reflection coefficient spectrum reconstruction on the remaining frequency components to obtain a cable positioning curve after interference peaks are suppressed.

[0008] The embodiment of the application decomposes the reflection coefficient spectrum into different frequency components in frequency descending order by taking the reflection coefficient spectrum as a pseudo-time domain spectrum, identifies and removes the first-end frequency component and the second-end frequency component, thereby reducing the positioning error caused by the interference signal. That is, after the frequency component corresponding to the first-end impedance mismatch and the multiple reflection signal is removed, the reflection coefficient spectrum is reconstructed and used for defect positioning, thereby overcoming the interference of the first-end impedance mismatch and the multiple reflection signal on the defect positioning result. The interference and misjudgment in the field application of cable defect positioning are reduced.

[0009] In an implementation manner of the application, the number of positioning peaks corresponding to the original positioning curve of the to-be-tested cable is determined, and the first-end frequency domain reflection coefficient data of the to-be-tested cable is processed by variational mode decomposition to obtain a plurality of frequency components, specifically including: determining the number of positioning peaks based on the number of wave crests in the original positioning curve of the to-be-tested cable; wherein the number of positioning peaks includes first-end peaks and last-end peaks; determining the number of frequency components based on a preset frequency component function: K=n+1; wherein K is the number of frequency components, and n is the number of positioning peaks; and decomposing the first-end frequency domain reflection coefficient data of the to-be-tested cable into a plurality of frequency components according to the variational mode decomposition processing method and the number of frequency components.

[0010] In an implementation manner of the application, the plurality of frequency components are matched with the plurality of positioning peaks based on frequency descending order, specifically including: performing first sorting on the plurality of frequency components according to the frequency descending order of the variational mode decomposition; performing second sorting on the plurality of positioning peaks based on the distance between the plurality of positioning peaks and the first end of the to-be-tested cable, and determining the types of the plurality of positioning peaks based on the second sorting; wherein the types of the positioning peaks at least include one of a cable first-end positioning peak, a cable defect positioning peak, a cable last-end positioning peak and a multiple reflection positioning peak; matching the plurality of frequency components with the plurality of positioning peaks based on the first sorting and the second sorting; and determining the types of the positioning peaks corresponding to the plurality of frequency components based on the matching result.

[0011] In an implementation form of the application, based on the matching result, the first interference frequency component corresponding to the cable to be tested is removed, specifically comprising: based on the matching result, determining the frequency component corresponding to the first-end positioning peak; and based on the matching result, determining the frequency component corresponding to the positioning peak of the multiple reflections after the cable end; taking the frequency component corresponding to the first-end positioning peak and the frequency component corresponding to the positioning peak of the multiple reflections after the cable end as the first interference frequency component for removal.

[0012] In an implementation form of the application, the correlation coefficients between the remaining frequency components and the preset frequency components are determined, and based on the correlation coefficients, the second interference frequency component corresponding to the cable to be tested is removed, specifically comprising: taking the frequency component corresponding to the first defect after the cable first end as the preset frequency component; determining the Pearson correlation coefficients between the preset frequency component and the remaining frequency components; and taking the remaining frequency component corresponding to the maximum Pearson correlation coefficient as the second interference frequency for removal.

[0013] In an implementation form of the application, the remaining frequency components are subjected to reflection coefficient spectrum reconstruction to obtain the cable positioning curve after suppressing the interference peaks, specifically comprising: based on the function:

[0014] Γ'(f) = IMF2 + IMF3 + … IMF j-1 + IMF j+1 + … IMF n ;

[0015] the reconstructed reflection coefficient spectrum is obtained; wherein Γ'(f) is the reconstructed reflection coefficient spectrum; IMF2 represents the 2nd order frequency component of Γ(f); IMF3 represents the 3rd order frequency component of Γ(f); IMF j-1 represents the (j-1)th order frequency component of Γ(f); IMF j+1 represents the (j+1)th order frequency component of Γ(f); IMF n represents the nth order frequency component of Γ(f); j is the order number corresponding to the second interference frequency; based on the reconstructed reflection coefficient spectrum, positioning conversion processing is performed to obtain the cable positioning curve after suppressing the interference peaks.

[0016] In an implementation form of the application, based on the reconstructed reflection coefficient spectrum, positioning conversion processing is performed to obtain the cable positioning curve after suppressing the interference peaks, specifically comprising: based on the function:

[0017] y(x) = FFT{imag[Γ'(f)]·Chebwin(N)};

[0018]

[0019] x = v t / 2;

[0020] The positioning conversion is completed to obtain the cable positioning curve after the interference peak is suppressed; wherein, y(x) is the cable positioning curve after the interference peak is suppressed; FFT represents fast Fourier transform; imag represents the phase angle of a complex number; Chebwin(N) is a Chebyshev window function; N is the window length, which is equal to the sampling point number of the network analyzer; Γ'(f) is the reconstructed reflection coefficient spectrum; k is the sampling point sequence number; t is the time variable sequence; Δf is the frequency interval between adjacent sweep points; x is the position variable sequence; v is the cable wave speed.

[0021] In an implementation manner of the present application, before the acquired first-end frequency domain reflection coefficient data of the to-be-tested cable is subjected to positioning conversion processing, the method further comprises: acquiring the first-end frequency domain reflection coefficient data of the to-be-tested cable by the network analyzer when the end of the to-be-tested cable is in an open circuit state; wherein, the network analyzer connects the cable core at the first end of the to-be-tested cable through the positive electrode of the network analyzer connecting clamp, and connects the metal shielding layer at the first end of the to-be-tested cable through the negative electrode of the network analyzer connecting clamp.

[0022] The cable defect positioning interference peak suppression device provided by the embodiment of the present application comprises: at least one processor; and a memory connected in communication with the at least one processor; wherein, the memory stores instructions executable 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 positioning conversion processing on the acquired first-end frequency domain reflection coefficient data of the to-be-tested cable to obtain the original positioning curve of the to-be-tested cable; determine the number of positioning peaks corresponding to the original positioning curve of the to-be-tested cable, and perform variational mode decomposition processing on the first-end frequency domain reflection coefficient data of the to-be-tested cable based on the number of positioning peaks to obtain a plurality of frequency components; match the plurality of frequency components with a plurality of positioning peaks based on frequency decreasing order; remove the first interference frequency component corresponding to the to-be-tested cable based on the matching result; determine the correlation coefficients between the remaining frequency components and preset frequency components, and remove the second interference frequency component corresponding to the to-be-tested cable based on the correlation coefficients; and perform reflection coefficient spectrum reconstruction on the remaining frequency components to obtain the cable positioning curve after the interference peak is suppressed.

[0023] The nonvolatile computer storage medium provided by the embodiment of the application stores computer executable instructions, and the computer executable instructions are configured to: perform positioning conversion processing on the obtained first-end frequency domain reflection coefficient data of the to-be-tested cable to obtain an original positioning curve of the to-be-tested cable; determine the number of positioning peaks corresponding to the original positioning curve of the to-be-tested cable, and perform variational mode decomposition processing on the first-end frequency domain reflection coefficient data of the to-be-tested cable based on the number of positioning peaks to obtain a plurality of frequency components; match the plurality of frequency components with a plurality of positioning peaks based on a frequency decreasing order; remove a first interference frequency component corresponding to the to-be-tested cable based on a matching result; determine a correlation coefficient between each of the remaining frequency components and a preset frequency component, and remove a second interference frequency component corresponding to the to-be-tested cable based on the correlation coefficient; and perform reflection coefficient spectrum reconstruction on the remaining frequency components to obtain a cable positioning curve after interference peaks are suppressed.

[0024] The above at least one technical solution adopted by the embodiment of the application can achieve the following beneficial effects: The embodiment of the application decomposes the reflection coefficient spectrum into different frequency components in a frequency decreasing order by taking the reflection coefficient spectrum as a pseudo-time domain spectrum, identifies and removes the first interference frequency component and the second interference frequency component, thereby reducing positioning errors caused by interference signals. That is, after removing the frequency components corresponding to the first-end impedance mismatch and the multiple reflection signals, the reflection coefficient spectrum is reconstructed and used for defect positioning, thereby overcoming the interference of the first-end impedance mismatch and the multiple reflection signals on the defect positioning result. Interference and misjudgment in the field application of cable defect positioning are reduced. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative labor. In the drawings:

[0026] Figure 1 A cable defect positioning interference peak suppression platform structure provided by the embodiment of the present application;

[0027] Figure 2 A cable defect positioning interference peak suppression method flowchart provided by the embodiment of the present application;

[0028] Figure 3 A positioning curve comparison chart in a first simulation experiment provided by the embodiment of the present application;

[0029] Figure 4 A positioning curve comparison chart in a second simulation experiment provided by the embodiment of the present application;

[0030] Figure 5 A comparison diagram of positioning curves in a first verification experiment provided in this application embodiment;

[0031] Figure 6 This application provides a positioning curve diagram of each component corresponding to a first decomposition order;

[0032] Figure 7 This application provides a positioning curve diagram of each component corresponding to a second decomposition order;

[0033] Figure 8 This application provides a positioning curve diagram of each component corresponding to the third decomposition order;

[0034] Figure 9 This is a schematic diagram of a cable defect location interference peak suppression device provided in an embodiment of this application.

[0035] Figure label:

[0036] 200: Cable defect location interference peak suppression device; 201: Processor; 202: Memory. Detailed Implementation

[0037] This application provides a method, device, and medium for suppressing interference peaks in cable defect location.

[0038] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0039] The technical solutions proposed in the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0040] Figure 1 This application provides a schematic diagram of a cable defect location interference peak suppression platform structure, as shown in the embodiments. Figure 1 As shown, the cable defect location interference peak suppression platform includes a network analyzer, an industrial control computer, and the cable under test.

[0041] In one embodiment of this application, when the end of the cable under test is in an open-circuit state, the frequency domain reflection coefficient data of the cable under test head is obtained by a network analyzer. The positive terminal of the network analyzer connection clamp is connected to the cable core at the cable head end, and the negative terminal of the network analyzer connection clamp is connected to the metal shielding layer at the cable head end.

[0042] Specifically, the signal connection line with a clamp drawn from the network analyzer is connected to the first end of the cable to be measured, the positive electrode of the clamp is connected to the cable core, and the negative electrode of the clamp is connected to the metal shielding layer of the cable. Under the condition that the end of the cable to be measured is kept open, the frequency domain reflection coefficient data of the first end of the cable is collected by the network analyzer.

[0043] Figure 2 A flow chart of a cable defect positioning interference peak suppression method provided for an embodiment of the present application is shown in FIG. 1. The cable defect positioning interference peak suppression method comprises the following steps: Figure 2

[0044] S101, the acquired frequency domain reflection coefficient data of the first end of the cable to be measured is subjected to positioning conversion processing to obtain the original positioning curve of the cable to be measured.

[0045] In an embodiment of the present application, the frequency domain reflection coefficient data of the first end of the cable to be measured collected by the network analyzer is subjected to positioning conversion processing to obtain the original positioning curve of the cable, and the specific function is as follows:

[0046] y(x)=FFT{imag[Γ(f)]·Chebwin(N)};

[0047]

[0048] x=v·t / 2;

[0049] wherein y(x) is the original positioning function of the cable; FFT represents fast Fourier transform; imag represents the phase angle of a complex number; Chebwin(N) is the Chebyshev window function; Γ(f) is the reflection coefficient spectrum; k is the sample point number; N is the window length, which is equal to the sample point number of the network analyzer here; t is the time variable sequence; Δf is the frequency interval between adjacent frequency points; x is the position variable sequence; v is the wave speed of the cable.

[0050] Further, the variation curve of y(x) with respect to x is drawn, and the original positioning curve of the cable is obtained.

[0051] S102, the number of positioning peaks corresponding to the original positioning curve of the cable to be measured is determined, and the frequency domain reflection coefficient data of the first end of the cable to be measured is subjected to variational mode decomposition processing based on the number of positioning peaks to obtain a plurality of frequency components.

[0052] In an embodiment of the present application, the number of positioning peaks is determined based on the number of wave crests in the original positioning curve of the cable to be measured; wherein the number of positioning peaks includes the first end peak and the end peak.

[0053] Based on the preset frequency component function:

[0054] K=n+1; ​

[0055] determining the number of frequency components; wherein K is the number of frequency components; and n is the number of locating peaks. According to the variational mode decomposition processing method and the number of frequency components, the cable head end frequency domain reflection coefficient data to be measured is decomposed into a plurality of frequency components.

[0056] Specifically, according to the cable original locating curve image, the number of locating peaks n (including the head end peak and the tail end peak) from the cable head end to the cable tail end is calculated, the variational mode decomposition processing is performed on the cable head end frequency domain reflection coefficient data Γ(f), and Γ(f) is decomposed into K frequency components according to the preset frequency component function.

[0057] S103, matching the plurality of frequency components with the plurality of locating peaks based on the frequency decreasing order.

[0058] In an embodiment of the present application, the plurality of frequency components is first sorted according to the frequency decreasing order of the variational mode decomposition. The plurality of locating peaks is second sorted based on the distance between the plurality of locating peaks and the cable head end, and the type of the plurality of locating peaks is determined based on the second sorting; wherein the type of the locating peak at least includes one of the cable head end locating peak, the cable defect locating peak, the cable tail end locating peak and the multiple reflection locating peak. The plurality of frequency components is matched with the plurality of locating peaks based on the first sorting and the second sorting. The type of the locating peak corresponding to each of the plurality of frequency components is determined based on the matching result.

[0059] Specifically, according to the frequency decreasing decomposition order of the variational mode decomposition, the reflection coefficient spectrum is decomposed in the frequency decreasing order as a pseudo time domain spectrum, and the local defects of the cable, the cable head end, the cable tail end and the multiple reflection correspond to each frequency component in the reflection coefficient spectrum, which is decomposed in the frequency decreasing order.

[0060] Further, according to the principle of the locating conversion algorithm, each frequency component in the frequency decreasing order is converted into each locating peak in the distance decreasing order in the locating graph. Therefore, the first order frequency component corresponds to the locating peak of the multiple reflection after the cable tail end, the second order frequency component corresponds to the locating peak of the cable tail end, and so on.

[0061] S104, removing the first interference frequency component corresponding to the cable to be measured based on the matching result.

[0062] In an embodiment of the present application, based on the matching result, the frequency component corresponding to the positioning peak at the cable head end is determined. Based on the matching result, the frequency component corresponding to the positioning peak of the multiple reflections after the cable end is determined. The frequency component corresponding to the positioning peak at the cable head end and the frequency component corresponding to the positioning peak of the multiple reflections after the cable end are removed as the first interference frequency component.

[0063] Specifically, due to the impedance mismatch between the characteristic impedance of the measured cable and the signal connection line of the frequency domain reflectometry test equipment, the test signal is folded and reflected at the impedance mismatch point, which causes a positioning peak to appear at the position of the cable head end in the positioning map, which is easily misjudged as a defect, causing the cable head end to become a blind area of defect positioning. Secondly, due to the multiple reflections of the test signal in the measured cable in a very short time, these multiple reflection signals are collected by the test equipment, which causes a false peak to appear in the positioning map, and the position corresponding to the false peak does not have a local defect, which interferes with the on-site test judgment. Therefore, through the matching result, the frequency component corresponding to the positioning peak at the cable head end is determined, and the frequency component corresponding to the positioning peak of the multiple reflections after the cable end is determined. The frequency component corresponding to the positioning peak at the cable head end and the frequency component corresponding to the positioning peak of the multiple reflections after the cable end are removed.

[0064] By removing these interference frequency components, the positioning error can be reduced, and the final positioning result is more accurate. The head-end positioning peak and the multiple reflection positioning peak may be misjudged as a fault point in the cable, thereby causing unnecessary maintenance work. By removing these interference frequency components, the misjudgment rate can be reduced, and the reliability of fault positioning can be improved.

[0065] S105, determine the correlation coefficient between each of the remaining frequency components and the preset frequency component, and remove the second interference frequency component corresponding to the measured cable based on the correlation coefficient.

[0066] In an embodiment of the present application, the frequency component corresponding to the positioning peak of the first defect after the cable head end is taken as the preset frequency component. The Pearson correlation coefficient between the preset frequency component and the remaining frequency components is determined. The remaining frequency component corresponding to the maximum Pearson correlation coefficient is removed as the second interference frequency.

[0067] Specifically, the n-th order component in the embodiment of the present application corresponds to the positioning peak of the first defect after the cable head end, and the test signal is reflected multiple times between the first defect and the cable head end, resulting in multiple reflection positioning peaks before the cable end. Compared with other frequency components, the frequency component corresponding to the multiple reflection signal has the closest correlation with the n-th order component, so by comparing the size of the Pearson correlation coefficient P between the n-th order component and the remaining components, the frequency component with the maximum Pearson correlation coefficient P is the component corresponding to the multiple reflection signal, which is removed.

[0068] The Pearson correlation coefficient P between the nth order component and the rest of the components is calculated, and the specific formula is as follows:

[0069]

[0070] Wherein, P is the Pearson correlation coefficient; X is the nth order component of Γ(f) decomposition; Y is any one of the rest of the components; i is the order of the frequency component.

[0071] S106, the remaining frequency components are reconstructed to obtain the cable positioning curve after suppressing the interference peak.

[0072] In an embodiment of the present application, the remaining frequency components are used to reconstruct the reflection coefficient spectrum. Based on the function:

[0073] Γ'(f) = IMF2 + IMF3 + … IMF j-1 + IMF j+1 + … IMF n ;

[0074] The reconstructed reflection coefficient spectrum is obtained. Wherein, Γ'(f) is the reconstructed reflection coefficient spectrum; IMF2 represents the 2nd order frequency component of Γ(f); IMF3 represents the 3rd order frequency component of Γ(f); IMF j-1 represents the j-1th order frequency component of Γ(f); IMF j+1 represents the j+1th order frequency component of Γ(f); IMF n represents the nth order frequency component of Γ(f); j is the order corresponding to the second interference frequency;

[0075] Based on the reconstructed reflection coefficient spectrum, the positioning conversion processing is performed to obtain the cable positioning curve after suppressing the interference peak.

[0076] In an embodiment of the present application, based on the function:

[0077] y(x) = FFT{imag[Γ'(f)]·Chebwin(N)};

[0078]

[0079] x = v·t / 2;

[0080] The positioning conversion is completed to obtain a cable positioning curve after suppressing interference peaks; wherein, y(x) is the cable positioning curve after suppressing interference peaks; FFT represents fast Fourier transform; imag represents the phase angle of a complex number; Chebwin(N) is a Chebyshev window function; N is a window length, equal to the sampling point number of the network analyzer; Γ'(f) is the reconstructed reflection coefficient spectrum; k is a sampling point sequence number; t is a time variable sequence; Δf is a frequency interval between adjacent sweep points; x is a position variable sequence; and v is a cable wave speed.

[0081] After removing the frequency components corresponding to the front-end impedance mismatch and multiple reflections in the reflection coefficient spectrum according to the above steps, a new reflection coefficient spectrum is reconstructed and used for defect positioning, which can effectively suppress the interference peaks of the front-end impedance mismatch and multiple reflections in the defect positioning map.

[0082] The following is a specific simulation and experimental verification:

[0083] (1) Simulation verification:

[0084] ① Simulation group one: the simulation object is a 10kV coaxial cable with a full length of 100m. The specific parameter settings of the simulation are shown in Table 1. A local defect is set at a position 50m away from the cable front end, and a signal connection line with an impedance mismatch of 0.8m is set at the cable front end. The sweep range is set to 0.01MHz-50MHz. Table 1 shows the parameter settings of the simulation:

[0085] Simulation parameters Values Wire core radius (mm) 3.5 Metallic shield radius (mm) 9.3 Wire core resistivity (Ω / m) 1.75 x 10 -8 ]] Metallic shield resistivity (Ω / m) 1.75 x 10 -8 ]]> XLPE permittivity (F / m) 2.04 x 10 -11 ]] XLPE conductivity (S / m) 1 x 10 -16 ]] Vacuum permeability (H / m) 4π x 10 -7 ]]

[0086] Table 1

[0087] Figure 3 A positioning curve comparison chart in a first simulation experiment provided by the embodiment of the present application is shown in FIG. 1, wherein the original positioning curve in the prior art is shown by a dashed line, and it can be seen that, in addition to the positioning peaks at the defect position of 50m and the cable end position of 100m, there are also an interference peak of the front-end mismatch at 0m and an interference peak of multiple reflections at 150m, which is obviously not conducive to making accurate judgments in field testing. Figure 3 The positioning curve obtained after using the method of the embodiment of the present application is shown by a solid line in FIG. 2, and it can be seen that the positioning peaks at the defect position of 50m and the cable end position of 100m required in field testing are retained, and the interference peaks of the front-end mismatch and multiple reflections at 0m and 150m are significantly reduced. The interference peak value comparison before and after using the method of the embodiment of the present application is shown in Table 2.

[0088] Figure 3

[0089]

[0090] Table 2​​

[0091] As shown in Table 2, the peak-to-peak value of the interference caused by the head-end impedance mismatch is reduced by 99.99% at 0 m, and the peak-to-peak value of the interference caused by the multiple reflection signal is reduced by 99.61% at 150 m after the end of the cable (100 m).

[0092] ②Simulation Group 2: The simulation object is a 10 kV coaxial cable with a total length of 100 m. The specific parameter settings of the simulation are the same as those in Table 1. A local defect is set at each of the positions 15.7 m and 90 m from the head end of the cable, and a signal connection line with an impedance mismatch of 0.8 m is set at the head end of the cable. The sweep range is 0.01 MHz to 50 MHz.

[0093] Figure 4 A positioning curve comparison chart in a second simulation experiment provided by the embodiment of the present application. The original positioning curve without using the method of the embodiment of the present application is shown by a dashed line. As can be seen, in addition to the positioning peaks at the defect positions of 15.7 m and 90 m and the cable end position of 100 m, there is an interference peak of the head-end mismatch at 0 m, there are interference peaks of multiple reflections at 31.5 m and 47.2 m before the end of the cable, and there are interference peaks of multiple reflections at 116.2 m, 177.3 m, etc. after the end of the cable. Figure 4 The positioning curve obtained after using the method of the embodiment of the present application is shown by a solid line. As can be seen, the positioning peaks at the defect positions of 15.7 m and 90 m and the cable end position of 100 m required in the field test are retained, and the interference peaks of the head-end mismatch and multiple reflections at 0 m, 31.5 m, 47.2 m, 116.2 m, 177.3 m, etc. are significantly reduced. The comparison of the interference peak values before and after using the embodiment of the present application is shown in Table 3.

[0094] The positioning curve obtained after using the method of the embodiment of the present application is shown by a solid line. As can be seen, the positioning peaks at the defect positions of 15.7 m and 90 m and the cable end position of 100 m required in the field test are retained, and the interference peaks of the head-end mismatch and multiple reflections at 0 m, 31.5 m, 47.2 m, 116.2 m, 177.3 m, etc. are significantly reduced. The comparison of the interference peak values before and after using the embodiment of the present application is shown in Table 3. Figure 4 The positioning curve obtained after using the method of the embodiment of the present application is shown by a solid line. As can be seen, the positioning peaks at the defect positions of 15.7 m and 90 m and the cable end position of 100 m required in the field test are retained, and the interference peaks of the head-end mismatch and multiple reflections at 0 m, 31.5 m, 47.2 m, 116.2 m, 177.3 m, etc. are significantly reduced. The comparison of the interference peak values before and after using the embodiment of the present application is shown in Table 3.

[0095]

[0096] Table 3

[0097] As shown in Table 3, the peak-to-peak value of the interference at 0 m is reduced by 99.77%, the peak-to-peak value of the interference at 31.5 m is reduced by 97.49%, the peak-to-peak value of the interference at 47.2 m is reduced by 77.63%, the peak-to-peak value of the interference at 116.2 m is reduced by 90.00%, and the peak-to-peak value of the interference at 177.3 m is reduced by 99.93%.

[0098] (2) Experimental verification:

[0099] ①Experimental Group 1: The experimental object is a 10 kV coaxial cable with a total length of 7 m and no local defects. The cable head is connected to a network analyzer through a signal connection line with a clamp. The sweep frequency range is set to 0.3 MHz to 400 MHz.

[0100] Figure 5 This is a comparison graph of positioning curves in a first verification experiment provided by an embodiment of the present application. The original positioning curve without using the method of the embodiment of the present application is as Figure 5 shown by the dashed line. It can be seen that in addition to the positioning peak at the cable end position of 7 m, the positioning curve also has an interference peak of head-end mismatch at 0 m, and interference peaks of multiple reflections at 13.8 m, 20.3 m, etc. after the cable end.

[0101] The positioning curve obtained after using the method of the embodiment of the present application is as Figure 5 shown by the solid line. It can be seen that the positioning peak at the cable end position of 7 m required in the on-site test is retained, and the interference peaks of head-end mismatch and multiple reflections at 0 m, 13.8 m, and 20.3 m are significantly reduced. The comparison of interference peak values before and after using the technology of the embodiment of the present application is shown in Table 4.

[0102]

[0103] Table 4

[0104] As shown in Table 4, the peak value of the interference peak at 0 m is reduced by 99.67%, the peak value of the interference peak at 13.8 m is reduced by 93.87%, and the peak value of the interference peak at 20.3 m is reduced by 88.08%. The technology of the embodiment of the present application can significantly reduce the interference of head-end impedance mismatch and multiple reflection signals on the positioning result.

[0105] ②Experimental Group 2: Keep the cable type, total length, cable state, and experimental conditions of "Experimental Group 1", change the order K of the reflection coefficient spectrum decomposition, and respectively make K > n + 1, K = n + 1, K < n + 1. In this group of data, the number of positioning peaks n from the cable head to the cable end of the original positioning curve is 2. Compare the positioning curves under different decomposition orders of the reflection coefficient spectrum:

[0106] (a) K > n + 1:

[0107] Figure 6 This is a positioning curve graph of each order component corresponding to a first decomposition order provided by an embodiment of the present application. When the decomposition order K = 4, that is, when K > n + 1, the positioning graphs corresponding to each order IMF component of its reflection coefficient spectrum decomposition are as Figure 6 shown.

[0108] From Figure 6It can be seen that when K>n+1, the frequency components corresponding to the interference peaks caused by the multiple reflections behind the cable end are decomposed into different IMF components (IMF1, IMF2), however, these components are not needed when reconstructing the reflection coefficient spectrum, and should be removed. Therefore, higher order decomposition of these interference peaks is redundant, which affects the data processing efficiency and positioning effect.

[0109] (b) K<n+1:

[0110] Figure 7 A second decomposition order corresponding to the positioning curve of each component provided by the embodiment of the present application is shown in the figure. When the decomposition order K=2, i.e. K<n+1, the positioning graph corresponding to each order IMF component of the reflection coefficient spectrum decomposition is as shown in Figure 7 .

[0111] From Figure 7 it can be seen that when K<n+1, the frequency components corresponding to the interference peaks caused by the multiple reflections behind the cable end and the positioning peaks of the cable end are decomposed into the same IMF component, the frequency components of the interference peaks should be removed, however, the frequency components of the end positioning peaks should be retained. Therefore, when the decomposition order K<n+1, the decomposition is insufficient, which affects the reconstruction of the reflection coefficient spectrum and the effectiveness of the algorithm processing result.

[0112] (c) K=n+1:

[0113] Figure 8 A third decomposition order corresponding to the positioning curve of each component provided by the embodiment of the present application is shown in the figure. When the decomposition order K=3, i.e. K=n+1, the positioning graph corresponding to each order IMF component of the reflection coefficient spectrum decomposition is as shown in Figure 8 .

[0114] From Figure 8 it can be seen that when K=n+1, the frequency components corresponding to the interference peaks caused by the multiple reflections behind the cable end are decomposed into the IMF1 component, the frequency components corresponding to the pseudo-peak of the first end impedance mismatch are decomposed into the IMF3 component, and the frequency components corresponding to the positioning peaks of the cable end are decomposed into the IMF2 component. The decomposition of these frequency components achieves independent effects, and the positioning curve Figure 5 after the reconstruction of the reflection coefficient spectrum successfully achieves the expected effect of the embodiment of the present application. It proves the correctness of the decomposition order K=n+1 of the reflection coefficient spectrum proposed in the embodiment of the present application.

[0115] Figure 9 A structural schematic diagram of a cable defect positioning interference peak suppression device provided by the embodiment of the present application is shown in the figure. Figure 9As shown, the cable defect positioning interference peak suppression device 200 comprises: at least one processor 201; and a memory 202 connected with the at least one processor 201 in communication; wherein the memory 202 stores instructions executable by the at least one processor 201, and the instructions are executed by the at least one processor 201 to enable the at least one processor 201 to: perform positioning conversion processing on the obtained first-end frequency domain reflection coefficient data of the to-be-tested cable to obtain an original positioning curve of the to-be-tested cable; determine the number of positioning peaks corresponding to the original positioning curve of the to-be-tested cable, and perform variational mode decomposition processing on the first-end frequency domain reflection coefficient data of the to-be-tested cable based on the number of positioning peaks to obtain a plurality of frequency components; match the plurality of frequency components with the plurality of positioning peaks based on a frequency decreasing order; remove the first interference frequency component corresponding to the to-be-tested cable based on the matching result; determine the correlation coefficients between the remaining frequency components and preset frequency components, and remove the second interference frequency component corresponding to the to-be-tested cable based on the correlation coefficients; and perform reflection coefficient spectrum reconstruction on the remaining frequency components to obtain a cable positioning curve after interference peaks are suppressed.

[0116] The non-volatile computer storage medium provided by the embodiments of the present application stores computer executable instructions, and the computer executable instructions are configured to: perform positioning conversion processing on the obtained first-end frequency domain reflection coefficient data of the to-be-tested cable to obtain an original positioning curve of the to-be-tested cable; determine the number of positioning peaks corresponding to the original positioning curve of the to-be-tested cable, and perform variational mode decomposition processing on the first-end frequency domain reflection coefficient data of the to-be-tested cable based on the number of positioning peaks to obtain a plurality of frequency components; match the plurality of frequency components with the plurality of positioning peaks based on a frequency decreasing order; remove the first interference frequency component corresponding to the to-be-tested cable based on the matching result; determine the correlation coefficients between the remaining frequency components and preset frequency components, and remove the second interference frequency component corresponding to the to-be-tested cable based on the correlation coefficients; and perform reflection coefficient spectrum reconstruction on the remaining frequency components to obtain a cable positioning curve after interference peaks are suppressed.

[0117] Each of the embodiments in the present application is described in a progressive manner, and the same or similar parts of each of the embodiments can be referred to each other. Each of the embodiments focuses on the difference from other embodiments. In particular, for the device, equipment, and non-volatile computer storage medium embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the part of the description of the method embodiments.

[0118] The above only describes the embodiments of the present application and is not used to limit the present application. The embodiments of the present application can be variously changed and modified by those skilled in the art. The modifications or replacements do not make the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for suppressing interference peaks in cable defect location, characterized in that, The method includes: The obtained frequency domain reflection coefficient data of the cable under test is processed by positioning transformation to obtain the original positioning curve of the cable under test. The number of positioning peaks corresponding to the original positioning curve of the cable under test is determined, and based on the number of positioning peaks, variational mode decomposition is performed on the frequency domain reflection coefficient data of the cable under test to obtain multiple frequency components. Based on the frequency decreasing order, multiple frequency components are matched with multiple positioning peaks; Based on the matching results, the first interference frequency component corresponding to the cable under test is removed; The correlation coefficients between the remaining frequency components and the preset frequency components are determined, and the second interference frequency component corresponding to the cable under test is removed based on the correlation coefficients. The remaining frequency components are reconstructed using the reflection coefficient spectrum to obtain the cable positioning curve after suppressing interference peaks.

2. The method for suppressing interference peaks in cable defect location according to claim 1, characterized in that, The method involves determining the number of positioning peaks corresponding to the original positioning curve of the cable under test, and based on the number of positioning peaks, performing variational mode decomposition on the frequency domain reflection coefficient data at the beginning of the cable under test to obtain multiple frequency components, specifically including: The number of positioning peaks is determined based on the number of peaks in the original positioning curve of the cable under test; wherein, the number of positioning peaks includes the first peak and the last peak; Based on preset frequency component functions: K = n + 1; The number of frequency components is determined; where K is the number of frequency components; and n is the number of localization peaks. Based on the variational mode decomposition processing method and the number of frequency components, the frequency domain reflection coefficient data of the cable under test is decomposed into multiple frequency components.

3. The method for suppressing interference peaks in cable defect location according to claim 1, characterized in that, The step of matching multiple frequency components with multiple location peaks based on a frequency decreasing order specifically includes: Based on the frequency decreasing order of variational mode decomposition, the multiple frequency components are first sorted. Based on the distance between the multiple positioning peaks and the beginning of the cable under test, the multiple positioning peaks are sorted in a second order, and multiple positioning peak types are determined based on the second order; wherein, the positioning peak type includes at least one of the following: cable beginning positioning peak, cable defect positioning peak, cable end positioning peak, and multiple reflection positioning peak; Based on the first sorting and the second sorting, multiple frequency components are matched with multiple location peaks; Based on the matching results, the localization peak types corresponding to the multiple frequency components are determined.

4. The method for suppressing interference peaks in cable defect location according to claim 1, characterized in that, Based on the matching results, the removal of the first interference frequency component corresponding to the cable under test specifically includes: Based on the matching results, the frequency components corresponding to the first-end positioning peak are determined; Furthermore, based on the matching results, the frequency components corresponding to the location peaks of the multiple reflections after the cable end are determined; The frequency component corresponding to the positioning peak at the beginning and the frequency component corresponding to the positioning peak of the multiple reflections after the end of the cable are used as the first interference frequency component and removed.

5. The method for suppressing interference peaks in cable defect location according to claim 1, characterized in that, The process of determining the correlation coefficients between the remaining frequency components and the preset frequency components, and removing the second interference frequency component corresponding to the cable under test based on the correlation coefficients, specifically includes: The frequency component corresponding to the location peak of the first defect after the cable head end is taken as the preset frequency component. The Pearson correlation coefficient between the preset frequency component and the remaining frequency component was determined; The remaining frequency component corresponding to the maximum Pearson correlation coefficient is removed as the second interference frequency.

6. The method for suppressing interference peaks in cable defect location according to claim 1, characterized in that, The step of reconstructing the reflection coefficient spectrum of the remaining frequency components to obtain the cable positioning curve after suppressing interference peaks specifically includes: Function-based: C′(f)=IMF2+IMF3+…IMF j-1 +IMF j+1 +…IMF n ; The reconstructed reflection coefficient spectrum is obtained; where Γ'(f) is the reconstructed reflection coefficient spectrum; IMF2 represents the second-order frequency component of Γ(f); IMF3 represents the third-order frequency component of Γ(f); IMF j-1 Represents the (j-1)th order frequency component of Γ(f); IMF j+1 Represents the (j+1)th order frequency component of Γ(f); IMF n Let Γ(f) represent the nth order frequency component; j is the order corresponding to the second interference frequency. Based on the reconstructed reflection coefficient spectrum, a positioning conversion process is performed to obtain the cable positioning curve after suppressing the interference peak.

7. The method for suppressing interference peaks in cable defect location according to claim 6, characterized in that, The positioning transformation process based on the reconstructed reflection coefficient spectrum to obtain the cable positioning curve after suppressing interference peaks specifically includes: Function-based: y(x)=FFT{imag[Γ′(f)]·Chebwin(N)}; x = v·t / 2; After completing the positioning transformation, the cable positioning curve after suppressing the interference peak is obtained; where y(x) is the cable positioning curve after suppressing the interference peak; FFT represents performing a fast Fourier transform; imag represents calculating the phase angle of a complex number; Chebwin(N) is the Chebyshev window function; N is the window length, which is equal to the number of sampling points of the network analyzer; Γ'(f) is the reconstructed reflection coefficient spectrum; k is the sampling point number; t is the time variable sequence; Δf is the frequency interval between adjacent sweep points; x is the position variable sequence; and v is the cable wave velocity.

8. The method for suppressing interference peaks in cable defect location according to claim 1, characterized in that, Before performing the location conversion processing on the acquired frequency domain reflection coefficient data of the cable under test, the method further includes: When the end of the cable under test is in an open circuit state, the frequency domain reflection coefficient data of the beginning of the cable under test is obtained by a network analyzer; The positive terminal of the network analyzer connection clamp is connected to the cable core at the beginning of the cable under test, and the negative terminal of the network analyzer connection clamp is connected to the metal shielding layer at the beginning of the cable under test.

9. A cable defect location interference peak suppression device, characterized in that, The device includes a memory for storing computer program instructions and a processor for executing the program instructions, wherein when the computer program instructions are executed by the processor, the device is triggered to perform the method described in any one of claims 1-8.

10. A non-volatile computer storage medium storing computer-executable instructions, characterized in that, The computer-executable instructions are capable of performing the method described in any one of claims 1-8.

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