Method and device for positioning cable hidden danger defect, electronic equipment and storage medium

Abstract

The invention discloses a method and device for positioning a cable hidden trouble defect, electronic equipment and a storage medium. The method comprises the following steps: acquiring an impedance spectrum of a to-be-detected cable in a healthy state and an impedance spectrum of the to-be-detected cable in a current running state; according to the relative dielectric constant of the main insulating layer of the to-be-measured cable, calculating a reference pseudo frequency for determining an impedance spectroscopy frequency interval; determining a reference frequency list corresponding to each to-be-analyzed data point in the to-be-analyzed positioning interval based on the reference pseudo frequency; respectively analyzing the impedance spectrum of the health state and the impedance spectrum of the current operation state as pseudo time domain signals by using the reference frequency list and adopting a digital lock-in amplifier algorithm to obtain corresponding analysis results; and according to a difference value of analysis results corresponding to the two impedance spectrums, positioning a hidden danger defect. According to the method and the device, the propagation coefficient rule of an ideal healthy cable does not need to be accurately mastered, the positioning interval and the step length can be actively specified, the frequency range and the step length limitation of the resistance spectrum are small, and the method and the device have relatively high defect identification capability and practicability.

Description

Technical Field

[0001] The present disclosure relates to the field of electrical engineering, and in particular, to a method, device, electronic device, and storage medium for analyzing a cable impedance spectrum based on a digital lock-in amplifier algorithm to locate hidden dangers and defects of a cable. Background Art

[0002] The frequency domain reflectometry is one of the important means for detecting power cable faults, and the cable impedance spectrum is the main object of study in the frequency domain reflectometry. Through the frequency domain reflectometry, potential hidden dangers and defects in the power cable can be detected in advance, avoiding losses that may be caused by their development into serious faults, which is of great significance for the operation and maintenance inspection of the cable.

[0003] Currently, there are mainly two methods for analyzing the cable impedance spectrum: the fast Fourier transform (FFT) method and the integral transform (IT) method. However, both of these methods have their own limitations.

[0004] The FFT method directly analyzes the measured impedance spectrum, and its positioning step size is affected by the selected time window and sampling rate. Moreover, when locating more minute hidden dangers and defects, the recognition ability of the FFT method is lacking.

[0005] The IT method combines the healthy impedance spectrum (which can be obtained by prior testing) and the measured impedance spectrum for analysis, and locates minute defects by comparing the difference in the integral transform analysis results of the two impedance spectra. However, the IT method requires accurate knowledge of the propagation coefficient law of the ideal healthy cable with frequency change, which is difficult in actual operation.

[0006] Therefore, there is an urgent need to propose a new method for analyzing the cable impedance spectrum, which can overcome the limitation of the positioning step size of the FFT method and does not require knowledge of the propagation coefficient law of the ideal healthy cable, thereby improving the practicality of cable hidden danger and defect location. Summary of the Invention

[0007] The present disclosure provides a method for analyzing a cable impedance spectrum based on a digital lock-in amplifier algorithm to locate hidden dangers and defects of a cable. By processing the impedance spectrum data as a pseudo-time domain signal and using the digital lock-in amplifier algorithm for analysis, the accuracy and practicality of cable hidden danger and defect location are improved.

[0008] According to an embodiment of the present disclosure, a method for locating hidden dangers and defects of a cable is proposed, including:

[0009] Obtaining the impedance spectrum of the cable to be measured in a healthy state and the impedance spectrum in the current operating state;

[0010] Calculating a reference pseudo-frequency for determining the impedance spectrum analysis frequency interval according to the relative permittivity of the main insulation layer of the cable to be measured;

[0011] Determine the reference frequency list corresponding to each data point to be analyzed in the positioning interval to be analyzed of the cable under test based on the reference pseudo-frequency;

[0012] Using the reference frequency list, analyze the impedance spectra in the healthy state and the current operating state as pseudo-time domain signals respectively by using the digital lock-in amplifier algorithm to obtain the corresponding analysis results;

[0013] Locate potential defects according to the difference between the analysis results corresponding to the impedance spectrum in the healthy state and the analysis results corresponding to the impedance spectrum in the current operating state.

[0014] In some embodiments, calculate the reference pseudo-frequency according to the following formula:

[0015] f0 = 2 * sqrt(epsilon) / (c * N0)

[0016] where epsilon is the relative permittivity of the main insulation layer of the cable under test, c is the speed of light, and N0 is the number of data points analyzed per meter.

[0017] In some embodiments, determine the reference frequency list F corresponding to each data point to be analyzed in the positioning interval to be analyzed according to the following formula:

[0018] F = [l 1 * N0 * f0:f0:l 2 * N0 * f0],

[0019] where [l 1 * N0 * f0:f0:l 2 * N0 * f0] represents an arithmetic progression from l 1 * N0 * f0 to l 2 * N0 * f0 with a step size of f0, where l 1 and l 2 are the start and end points of the positioning interval to be analyzed, and f0 is the reference pseudo-frequency.

[0020] In some embodiments, using the digital lock-in amplifier algorithm to analyze the impedance spectra in the healthy state and the current operating state as pseudo-time domain signals respectively to obtain the corresponding analysis results, including: for the i-th data point to be analyzed,

[0021] Select cos(w i t) as the first reference signal, multiply it with the currently input impedance spectrum and obtain the X component through low-pass filtering, where w i is the i-th frequency in the reference frequency list;

[0022] Select sin(w i t) as the second reference signal, multiply it with the currently input impedance spectrum and obtain the Y component through low-pass filtering;

[0023] According to the X and / or Y components, the analysis result corresponding to the i-th data point to be analyzed is obtained.

[0024] In some implementations, locating hidden dangers and defects according to the difference in analysis results includes:

[0025] Calculate R=DLIA(Zh)-DLIA(Zt),

[0026] Among them, DLIA(Zh) is the analysis result corresponding to the impedance spectrum in the healthy state, and DLIA(Zt) is the analysis result obtained by the impedance spectrum in the current operating state;

[0027] Determine whether there is a hidden defect based on the R value, and determine the location of the hidden defect based on the horizontal coordinate corresponding to the R value where the hidden defect exists.

[0028] In some embodiments, the impedance spectrum of the healthy state is obtained before the cable is put into operation, and the impedance spectrum of the current operating state is obtained during the operation of the cable.

[0029] According to one embodiment of the present disclosure, a device for locating hidden defects of cables is also provided, comprising:

[0030] An impedance spectrum acquisition unit, used to acquire the impedance spectrum of the tested cable in a healthy state and the impedance spectrum of the current operating state;

[0031] A reference pseudo frequency calculation unit, used for calculating a reference pseudo frequency for determining a frequency interval of impedance spectrum analysis according to a relative dielectric constant of a main insulation layer of a cable to be tested;

[0032] A reference frequency list calculation unit, used to determine a reference frequency list corresponding to each to-be-analyzed data point in the to-be-analyzed positioning interval of the cable to be tested based on the reference pseudo frequency;

[0033] A digital lock-in amplifier algorithm analysis unit is used to use the reference frequency list and the digital lock-in amplifier algorithm to analyze the impedance spectrum of the healthy state and the impedance spectrum of the current operating state as pseudo time domain signals to obtain corresponding analysis results;

[0034] The hidden danger locating unit is used to locate hidden danger defects according to the difference between the analysis result corresponding to the impedance spectrum of the healthy state and the analysis result corresponding to the impedance spectrum of the current operating state.

[0035] In some implementations, the reference pseudo frequency calculation unit is used to calculate the reference pseudo frequency according to the following formula:

[0036] f0=2*sqrt(epsilon) / (c*N0)

[0037] Wherein, epsilon is the relative permittivity of the main insulation layer of the cable to be measured, c is the speed of light, and N0 is the number of data points analyzed per meter.

[0038] In some embodiments, the reference frequency list calculation unit is configured to determine a reference frequency list F according to the following formula:

[0039] F = [l 1 *N0*f0:f0:l 2 *N0*f0],

[0040] Wherein, [l 1 *N0*f0:f0:l 2 *N0*f0] represents an arithmetic progression from l 1 *N0*f0 to l 2 *N0*f0 with a step size of f0, where l 1 and l 2 are the start and end points of the interval to be analyzed and located, and f0 is the reference pseudo-frequency.

[0041] In some embodiments, the digital lock-in amplifier algorithm analysis unit is configured to: for the i-th data point to be analyzed,

[0042] select cos(w i t) as the first reference signal, multiply it with the currently input impedance spectrum and obtain the X component through low-pass filtering, where w i is the i-th frequency in the reference frequency list;

[0043] select sin(w i t) as the second reference signal, multiply it with the currently input impedance spectrum and obtain the Y component through low-pass filtering;

[0044] obtain the analysis result corresponding to the i-th data point to be analyzed according to the X and / or Y components.

[0045] According to an embodiment of the present disclosure, an electronic device is provided. The device includes a memory and a processor. The memory is used to store computer instructions that can be run on the processor, and the processor is used to implement the method described in any one of the above when executing the computer instructions.

[0046] According to an embodiment of the present disclosure, a computer-readable storage medium is provided, on which a computer program is stored. When the program is executed by a processor, the method described in any one of the above is implemented.

[0047] The method for locating hidden dangers and defects of cables proposed in this disclosure overcomes the limitations of the existing FFT method and IT method by using the impedance spectrum as a pseudo-time-domain signal and processing it with a digital lock-in amplifier. Compared with the FFT method, the solution proposed in this disclosure is less affected by the limitations of the frequency range and frequency step of the impedance spectrum itself. It can actively specify the location range and step size, and freely select the analysis frequency point list, greatly improving the analysis flexibility. In addition, the solution proposed in this disclosure also shows a stronger ability to identify hidden dangers and defects. Experimental results show that for a weak fault set at 80m, the present invention can clearly identify this position, while the FFT method can hardly achieve effective identification.

[0048] Compared with the IT method, the most significant advantage of this disclosure is that it does not need to accurately master the law of the propagation coefficient of the ideal healthy cable changing with frequency, greatly reducing the usage threshold. In particular, this simplification does not affect the final identification effect. Experimental results show that the solution proposed in this disclosure and the IT method show comparable accuracy in identifying the cable fault location, and both can accurately locate the cable fault at 80m.

[0049] The solution for locating hidden dangers and defects of cables proposed in this disclosure avoids relying on complex propagation coefficient laws, while maintaining a strong fault identification ability, making the cable impedance spectrum analysis have more practical operation performance, significantly improving the engineering application value, and being very suitable for popularization and application in actual engineering.

[0050] Other features and advantages of the technical solution proposed in this disclosure are described in detail below. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The accompanying drawings here are incorporated into the specification and constitute a part of this specification, showing embodiments consistent with this specification, and are used together with the specification to explain the principles of this specification.

[0052] Figure 1 Shows a flowchart of a method for locating hidden dangers and defects of cables according to an embodiment of this disclosure.

[0053] Figure 2 Shows the impedance spectrum of the cable under test in a healthy state and the impedance spectrum in the current operating state obtained according to an exemplary embodiment of this disclosure.

[0054] Figure 3 Shows a schematic diagram for locating hidden dangers and defects of cables based on the analysis results of the digital lock-in amplifier algorithm according to an exemplary embodiment of this disclosure.

[0055] Figure 4 Is a schematic diagram of the structure of an electronic device shown in at least one embodiment of this disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0056] Exemplary embodiments will be described in detail herein, and examples thereof are shown in the accompanying drawings. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0057] Embodiments of the present disclosure can be applied to a computer system / server, which can operate with many other general-purpose or special-purpose computing system environments or configurations. Examples of well-known computing systems, environments, and / or configurations suitable for use with a computer system / server include, but are not limited to: personal computer systems, server computer systems, thin clients, thick clients, handheld or laptop devices, microprocessor-based systems, set-top boxes, programmable consumer electronics, network personal computers, minicomputer systems, mainframe computer systems, and distributed cloud computing technology environments including any of the above systems, and so on.

[0058] The computer system / server can be described in the general context of computer system-executable instructions, such as program modules, executed by the computer system. Generally, program modules can include routines, programs, object programs, components, logic, data structures, etc., which perform specific tasks or implement specific abstract data types. The computer system / server can be implemented in a distributed cloud computing environment, where tasks are executed by remote processing devices linked through a communication network. In a distributed cloud computing environment, program modules can be located on local or remote computing system storage media including storage devices.

[0059] Figure 1 A flowchart of a method for analyzing a cable impedance spectrum based on a digital lock-in amplifier algorithm to locate cable hidden danger defects according to an embodiment of the present disclosure is shown. As Figure 1 shown, the method includes steps 1 to 5.

[0060] Step 1, obtain the impedance spectrum of the cable to be measured in a healthy state and the impedance spectrum in the current operating state.

[0061] The impedance spectrum of the cable to be measured in a healthy state can be obtained by testing before the cable is put into operation. The cable can be regarded as being in a fault-free state before being put into operation, and the impedance spectrum measured at this time can be used as a reference benchmark for the subsequent operation stage.

[0062] In some examples, the impedance spectrum test can be performed using test equipment such as impedance analyzers or network vector analyzers commonly used in the art. For example, a precision impedance analyzer TH285-030 can be used, and appropriate frequency test ranges (such as 1 to 30 MHz) and the number of sampling points (such as 1601 points) can be set for the test. In practical applications, the selection of test equipment and the setting of test parameters can be adjusted according to factors such as the specific cable type and test environment.

[0063] When detecting whether there are potential hidden defects in the cable under the current operating state, the same test equipment and parameter configuration as those for the healthy state test can be used to test the cable during its operation to obtain the impedance spectrum of the current operating state, so as to ensure the comparability of test results.

[0064] In one example, during the impedance spectrum test, the test equipment can adopt a frequency sweep method, input signals of different frequencies to the cable, and measure the corresponding impedance characteristics. The test results can reflect the impedance change of the cable at different frequencies. When there are potential hidden defects in the cable, the defect location will affect signal transmission.

[0065] Step 2: Calculate the reference pseudo-frequency used to determine the frequency interval of impedance spectrum analysis according to the relative permittivity of the main insulation layer of the cable to be tested.

[0066] The main insulation layer is the most important insulation part in the cable, which is used to isolate the conductor and the shielding layer, and its relative permittivity will affect the propagation characteristics of electromagnetic waves in the cable. In practical applications, the relative permittivity of the main insulation layer of the cable can be obtained by referring to the product technical manual or measured by a special permittivity tester. The reference pseudo-frequency can be calculated according to the relative permittivity of the main insulation layer of the cable to be tested, and the reference pseudo-frequency is an important parameter in the subsequent analysis process.

[0067] In this embodiment, the reference pseudo-frequency is creatively calculated for determining the frequency interval of impedance spectrum analysis. In some embodiments, the reference pseudo-frequency can be calculated according to the following formula:

[0068] f0 = 2 * sqrt(epsilon) / (c * N0)

[0069] where epsilon is the relative permittivity of the main insulation layer of the cable to be tested, c is the speed of light, and N0 is the number of data points analyzed per meter.

[0070] According to the above formula, the reference pseudo-frequency is calculated by combining the cable dielectric characteristics (through the relative permittivity), the electromagnetic wave propagation characteristics (through the speed of light), and the analysis accuracy requirement (through the number of data points analyzed per meter). Among them, the reference pseudo-frequency f0 is proportional to the square root of the relative permittivity epsilon and inversely proportional to the number of data points N0 analyzed per meter. The number of data points N0 analyzed per meter is a user-selectable parameter that can be used to control the analysis accuracy. The larger N0 is, the smaller the reference pseudo-frequency is, and a more refined analysis result can be obtained.

[0071] The reference pseudo-frequency calculated according to this embodiment lays the foundation for subsequent processing of the impedance spectrum as a pseudo-time domain signal. In the above calculation, not only the influence of the main insulation medium of the cable on the electromagnetic wave propagation is considered, but also the flexible control of the analysis accuracy is realized by reasonably setting the number of data points analyzed per meter, so that the subsequent analysis results can accurately reflect the position information of potential defects in the cable. In practical applications, an appropriate relative permittivity value can be selected according to the cable type, and an appropriate number of data points analyzed per meter can be selected in combination with the required positioning accuracy requirement to obtain an ideal analysis effect.

[0072] Step 3, based on the reference pseudo-frequency, determine the reference frequency list corresponding to each data point to be analyzed in the positioning interval to be analyzed of the cable to be measured.

[0073] After obtaining the reference pseudo-frequency, the positioning interval to be analyzed can be determined according to the actual situation of the cable to be measured, and a reference frequency list corresponding to each data point to be analyzed is generated. The positioning interval to be analyzed is a section selected within the length range of the cable to be measured, which is used to determine which section of the cable to specifically analyze. In practical applications, the positioning interval to be analyzed can be selected according to factors such as operation and maintenance requirements and fault prediction. The number of data points N0 analyzed per meter is a user-selectable parameter, and 1 / N0 meters is used as the sampling step of the interval.

[0074] In some embodiments, the reference frequency list can be calculated according to the following formula:

[0075] F = [l 1 *N0*f0:f0:l 2 *N0*f0],

[0076] The above formula indicates that the reference frequency list F is an arithmetic progression from l 1 *N0*f0 to l 2 *N0*f0 with a step size of f0, where l 1 and l 2 are the start and end points of the positioning interval to be analyzed, and f0 is the reference pseudo-frequency.

[0077] The method for generating the reference frequency list proposed in this embodiment ensures that the subsequent analysis by the digital lock-in amplifier can cover the entire interval to be analyzed while maintaining an appropriate frequency resolution.

[0078] Different from the FFT method, which is passively limited by the frequency range and frequency step of the impedance spectrum itself, this embodiment can actively and flexibly set the interval to be analyzed and located according to actual needs, and achieve precise analysis of this interval through a reasonably constructed reference frequency list. Each frequency in the reference frequency list will be used as the reference frequency for the subsequent analysis by the digital lock-in amplifier, and the number of final analysis results corresponds to the number of frequencies in the reference frequency list.

[0079] In practical applications, the starting point and ending point of the interval to be analyzed and located can be flexibly selected according to factors such as cable length and the position of the section of interest. At the same time, as analyzed above, by adjusting the number of data points N0 analyzed per meter, a balance can be achieved between analysis accuracy and computational complexity. For example, when more refined analysis of a certain suspicious section is required, the value of N0 can be appropriately increased to obtain more dense analysis results.

[0080] Step 4: Using the reference frequency list, the impedance spectra in the healthy state and the current operating state are respectively analyzed as pseudo-time domain signals by using the digital lock-in amplifier algorithm to obtain corresponding analysis results.

[0081] In this embodiment, the impedance spectrum is processed as a pseudo-time domain signal and analyzed by using the digital lock-in amplifier algorithm. The basic principle of the digital lock-in amplifier is introduced below.

[0082] A digital lock-in amplifier (DLIA) is a high-precision measuring device used to extract weak signals at specific frequencies from a complex signal environment. It generates orthogonal reference signals for phase locking and digital processing, and can accurately measure the amplitude and phase of signals in a high-noise background. The dual-channel DLIA has two independent input channels and can simultaneously measure the orthogonal components (such as X and Y components) of the input signal, which is particularly suitable for application scenarios that require synchronous processing of multiple signal sources or complex vector analysis, such as precision optical measurement, material property research, and signal processing of high-sensitivity sensors.

[0083] For the input signal Vin(t), when using the first reference signal cos(wt), the following can be obtained through multiplication by a multiplier:

[0084] Vmix1(t) = V w / 2 * [cos(phi) + cos(2wt + phi)] + delta,

[0085] Among them, Vmix1 is the signal after multiplication, V w is the amplitude of the w-frequency component in Vin(t), phi is the phase of the w-frequency component, and delta is the noise term generated by the multiplication of the multiplier. The Vmix1(t) signal is low-pass filtered to obtain the low-frequency quantity V w / 2*cos(phi), denoted as X.

[0086] Similarly, using the second reference signal sin(wt), after passing through the multiplier and the low-pass filter, the low-frequency quantity V w / 2*sin(phi) is obtained and denoted as Y.

[0087] The output result of the digital lock-in amplifier is usually the complex number X + jY.

[0088] Based on the complex number result X + jY output by the digital lock-in amplifier, the amplitude Z and phase theta of the w-frequency component in Vin(t) can be extracted:

[0089] Z = sqrt(X^2 + Y^2), theta = arctan(Y / X).

[0090] The above is the basic principle of the digital lock-in amplifier algorithm.

[0091] The greatest advantage of the digital lock-in amplifier in extracting frequency components lies in its anti-interference ability and the ability for the user to determine the frequency list by themselves.

[0092] According to some embodiments of this embodiment, analyzing the impedance spectrum as a pseudo-time domain signal using the digital lock-in amplifier algorithm may include: for the i-th data point to be analyzed,

[0093] select cos(w i t) as the first reference signal, multiply it with the currently input impedance spectrum and obtain the X component through low-pass filtering, w i is the i-th frequency in the reference frequency list;

[0094] select sin(w i t) as the second reference signal, multiply it with the currently input impedance spectrum and obtain the Y component through low-pass filtering;

[0095] According to the X and / or Y components, obtain the analysis result corresponding to the i-th data point to be analyzed.

[0096] In some examples, the real part (i.e., the X component) of the output of the digital lock-in amplifier algorithm can be used as the analysis result for subsequent processing; in other examples, the imaginary part (i.e., the Y component) of the output of the digital lock-in amplifier algorithm can be used as the analysis result for subsequent processing; in other embodiments, the amplitude Z extracted based on the real part X and the imaginary part Y can be used as the analysis result. When analyzing different impedance spectra, the same result selection criteria should be adopted.

[0097] The above analysis process can be performed on the impedance spectra of the healthy state and the current operating state respectively. For each impedance spectrum, the above processing should be performed in sequence using all the frequencies in the reference frequency list. In this way, a corresponding set of analysis results will be obtained for each impedance spectrum.

[0098] In step 4, the impedance spectrum in the frequency domain is processed as a time-domain signal, and through the characteristics of the digital lock-in amplifier, an accurate analysis of the impedance spectrum is achieved. Compared with the traditional FFT method, this method is less affected by the limitations of the frequency range and frequency step size of the impedance spectrum itself, and can actively define the positioning interval and step size; compared with the IT method, it does not require knowledge of the propagation coefficient law of the ideal healthy cable, thus providing a reliable analysis basis for subsequent defect location.

[0099] Step 5, locate potential hidden defects based on the difference between the analysis results corresponding to the impedance spectrum of the healthy state and the analysis results corresponding to the impedance spectrum of the current operating state.

[0100] After analyzing the impedance spectra of the healthy state and the current operating state respectively based on the digital lock-in amplifier algorithm, the analysis results can be compared to locate potential hidden defects.

[0101] In some embodiments, locating potential hidden defects based on the difference in the analysis results includes:

[0102] Calculate R = DLIA(Zh) - DLIA(Zt),

[0103] where DLIA(Zh) is the analysis result corresponding to the impedance spectrum of the healthy state, and DLIA(Zt) is the analysis result obtained from the impedance spectrum of the current operating state;

[0104] Judge whether there are potential hidden defects according to the value of R, and determine the location of the potential hidden defects according to the abscissa corresponding to R with potential hidden defects.

[0105] By taking the difference between the analysis results of the healthy state and the current operating state, the differential characteristics of the impedance spectra in the two states are found. When there are potential defects in the cable, the signal transmission at this location will be affected, resulting in a change in the impedance spectrum of the current operating state relative to the healthy state. By treating the impedance spectrum as a pseudo-time-domain signal and using the digital lock-in amplifier algorithm for processing, the results can highlight this change. This processing method has a stronger ability to extract defect characteristics and can identify changes that are difficult to detect by the FFT method.

[0106] The abscissa of the R value corresponds to the N0 sampling positions with an interval of 1 / N0 in the analysis and positioning interval [l 1 , l 2 . When a significant change in the R value occurs at a certain position, it indicates that there may be potential defects at this position.

[0107] In practical applications, corresponding judgment criteria can be established based on the characteristics of the R value change (such as amplitude, shape, etc.) to improve the accuracy of defect identification. At the same time, factors such as the historical operation data of the cable and expert experience can also be combined to comprehensively evaluate the analysis results, so as to make a more reliable judgment.

[0108] The method for analyzing the cable impedance spectrum based on the digital lock-in amplifier algorithm to locate potential cable defects provided in this embodiment realizes the accurate positioning of potential cable defects by innovatively treating the impedance spectrum as a pseudo-time-domain signal and combining the analysis ability of the digital lock-in amplifier algorithm. Compared with the traditional FFT method, this embodiment is less affected by the limitations of the frequency range and frequency step size of the impedance spectrum itself, can actively specify the positioning interval and step size, freely select the analysis frequency point list, significantly improves the analysis flexibility, and has a stronger ability to extract defect characteristics. Compared with the IT method, this embodiment does not need to accurately master the propagation coefficient law of the ideal healthy cable with frequency change, greatly reduces the use threshold, and at the same time maintains excellent recognition effects. In particular, through the innovative design of the reference pseudo-frequency and the reasonable frequency list generation method, the cable impedance spectrum analysis has more practical operation performance, which strongly promotes the popularization and application of the frequency domain reflectometry method for locating weak cable faults based on cable impedance spectrum analysis in practical engineering.

[0109] The following gives a specific application example of the present disclosure.

[0110] On-site, a precision impedance analyzer TH285-030 was used to measure a 140m-long cable, with a weak potential defect set at 80m. A total of 1601 points were measured during the test, and the frequency range was 1 - 30 MHz.

[0111] First, before manufacturing the defect, the impedance spectrum Zh of the cable system was tested, and then a defect was manufactured at 80m, and the impedance spectrum of the cable system was tested again as Zf. The measured impedance spectra are asFigure 2 shown.

[0112] The method of analyzing the cable impedance spectrum based on the digital phase-locked amplifier algorithm proposed in the present disclosure to locate the hidden dangers of the cable (which can be referred to as the DLIA method), the FFT method and the IT method are used to analyze and locate the weak hidden danger at 80m. When using the DLIA analysis, the relative dielectric constant of the cable to be tested is given as 2.3. The test results are used to analyze the faults of the cable. Figure 3 shown.

[0113] from Figure 3 It can be seen from the results shown that the positioning result of the method proposed in the present invention for analyzing the cable impedance spectrum based on the digital phase-locked amplifier algorithm to locate the hidden defects of the cable can accurately identify the location of the cable fault like the IT method, but the FFT can hardly identify the location of the fault. On the other hand, compared with the IT method, the method proposed in the present invention does not need to accurately grasp the law of the propagation coefficient of the ideal healthy cable changing with frequency, which greatly reduces the threshold for use and further verifies the correctness and feasibility of the solution proposed in this patent.

[0114] The present disclosure also proposes a device for locating hidden defects of cables, comprising:

[0115] An impedance spectrum acquisition unit, used to acquire the impedance spectrum of the tested cable in a healthy state and the impedance spectrum of the current operating state;

[0116] A reference pseudo frequency calculation unit, used for calculating a reference pseudo frequency for determining a frequency interval of impedance spectrum analysis according to a relative dielectric constant of a main insulation layer of a cable to be tested;

[0117] A reference frequency list calculation unit, used to determine a reference frequency list corresponding to each to-be-analyzed data point in the to-be-analyzed positioning interval of the to-be-tested cable based on the reference pseudo frequency;

[0118] A digital lock-in amplifier algorithm analysis unit is used to use the reference frequency list and the digital lock-in amplifier algorithm to analyze the impedance spectrum of the healthy state and the impedance spectrum of the current operating state as pseudo time domain signals to obtain corresponding analysis results;

[0119] The hidden danger locating unit is used to locate hidden danger defects according to the difference between the analysis result corresponding to the impedance spectrum of the healthy state and the analysis result corresponding to the impedance spectrum of the current operating state.

[0120] For other details and features of this embodiment, please refer to the relevant description above.

[0121] Figure 4An electronic device provided by at least one embodiment of the present disclosure, the device includes a memory and a processor, the memory is used to store computer instructions that can run on the processor, and the processor is used to implement the method for analyzing the cable impedance spectrum based on the digital lock-in amplifier algorithm to locate cable hidden dangers and defects described in any embodiment or implementation manner of the present disclosure when executing the computer instructions.

[0122] At least one embodiment of the present disclosure also provides a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, it implements the method for analyzing the cable impedance spectrum based on the digital lock-in amplifier algorithm to locate cable hidden dangers and defects described in any embodiment or implementation manner of the present disclosure.

[0123] Those skilled in the art should understand that one or more embodiments of this specification can be provided as a method, a system, or a computer program product. Therefore, one or more embodiments of this specification can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, one or more embodiments of this specification can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) containing computer-usable program code.

[0124] Each embodiment in this specification is described in a progressive manner. The same or similar parts between each embodiment can be referred to each other, and the key point of each embodiment is to illustrate the differences from other embodiments. In particular, for the data processing device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0125] The above describes specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be executed in a different order than in the embodiments and still achieve the desired results. Additionally, the processes depicted in the figures do not necessarily require the particular order or sequential order shown to achieve the desired results. In certain implementations, multitasking and parallel processing are also possible or may be advantageous.

[0126] Although this specification contains many specific implementation details, these should not be construed as limiting the scope of any invention or the scope of what is claimed, but rather as mainly describing the features of specific embodiments of a particular invention. Certain features described in multiple embodiments in this specification can also be implemented in combination in a single embodiment. On the other hand, the various features described in a single embodiment can also be implemented separately in multiple embodiments or in any suitable sub-combination. Additionally, although features may operate in certain combinations as described above and even be initially claimed as such, one or more features from a claimed combination can in some cases be removed from that combination, and the claimed combination can be directed to a sub-combination or a variation of a sub-combination.

[0127] Similarly, although operations are depicted in the figures in a particular order, this should not be construed as requiring that the operations be performed in the particular order shown or sequentially, or that all illustrated operations be performed to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Additionally, the separation of the various system modules and components in the above embodiments should not be construed as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

[0128] Thus, specific embodiments of the subject matter have been described. Other embodiments are within the scope of the appended claims. In some cases, the acts recited in the claims can be performed in a different order and still achieve the desired result. Additionally, the processes depicted in the figures are not necessarily in the particular order or sequential order shown to achieve the desired result. In some implementations, multitasking and parallel processing may be advantageous.

[0129] The above description is only the preferred embodiment of one or more embodiments of this specification and is not intended to limit one or more embodiments of this specification. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of one or more embodiments of this specification should be included within the scope of protection of one or more embodiments of this specification.

Claims

1. A method for locating hidden defects of cables, characterized in that: include: Obtain the impedance spectrum of the cable under test in a healthy state and the impedance spectrum of the cable under current operation state; According to the relative dielectric constant of the main insulation layer of the cable to be tested, the reference pseudo frequency used to determine the frequency interval of impedance spectrum analysis is calculated; Determine a reference frequency list corresponding to each data point to be analyzed in the positioning interval to be analyzed of the cable to be tested based on the reference pseudo frequency; Using the reference frequency list, a digital lock-in amplifier algorithm is used to analyze the impedance spectrum of the healthy state and the impedance spectrum of the current operating state as pseudo time domain signals to obtain corresponding analysis results; Hidden dangers and defects are located based on the difference between the analysis results corresponding to the impedance spectrum in the healthy state and the analysis results corresponding to the impedance spectrum in the current operating state.

2. The method according to claim 1, characterized in that The reference pseudo frequency is calculated according to the following formula: f0=2*sqrt(epsilon) / (c*N0) Where epsilon is the relative dielectric constant of the main insulation layer of the cable to be tested, c is the speed of light, and N0 is the number of data points analyzed per meter.

3. The method according to claim 2, characterized in that Determine the reference frequency list F corresponding to each data point to be analyzed in the positioning interval to be analyzed according to the following formula: F=[l1*N0*f0:f0:l2*N0*f0], Among them, [l1*N0*f0:f0:l2*N0*f0] represents an arithmetic progression from l1*N0*f0 to l2*N0*f0 with a step length of f0, where l1 and l2 are the starting point and end point of the positioning interval to be analyzed, and f0 is the reference pseudo frequency.

4. The method according to claim 1, characterized in that: The impedance spectrum of the healthy state and the impedance spectrum of the current operating state are analyzed as pseudo time domain signals using the digital lock-in amplifier algorithm to obtain the corresponding analysis results, including: for the i-th data point to be analyzed, Select cos(w i t) is used as the first reference signal, multiplied by the current input impedance spectrum and filtered through a low pass filter to obtain the X component, w i is the i-th frequency in the reference frequency list; Select sin(w i t) as a second reference signal, multiplied with the impedance spectrum of the current input and obtained by low-pass filtering the Y component; According to the X and / or Y components, the analysis result corresponding to the i-th data point to be analyzed is obtained.

5. The method according to claim 1, characterized in that The hidden dangers and defects located based on the difference in analysis results include: Calculate R=DLIA(Zh)-DLIA(Zt), Among them, DLIA(Zh) is the analysis result corresponding to the impedance spectrum in the healthy state, and DLIA(Zt) is the analysis result obtained by the impedance spectrum in the current operating state; Determine whether there is a hidden defect based on the R value, and determine the location of the hidden defect based on the horizontal coordinate corresponding to the R value where the hidden defect exists.

6. The method according to claim 1, characterized in that The impedance spectrum of the healthy state is obtained before the cable is put into operation, and the impedance spectrum of the current operating state is obtained during the operation of the cable.

7. A device for locating hidden defects in cables, characterized in that: include: An impedance spectrum acquisition unit, used to acquire the impedance spectrum of the tested cable in a healthy state and the impedance spectrum of the current operating state; A reference pseudo frequency calculation unit, used for calculating a reference pseudo frequency for determining a frequency interval of impedance spectrum analysis according to a relative dielectric constant of a main insulation layer of a cable to be tested; A reference frequency list calculation unit, used to determine a reference frequency list corresponding to each to-be-analyzed data point in the to-be-analyzed positioning interval of the cable to be tested based on the reference pseudo frequency; A digital lock-in amplifier algorithm analysis unit is used to use the reference frequency list and the digital lock-in amplifier algorithm to analyze the impedance spectrum of the healthy state and the impedance spectrum of the current operating state as pseudo time domain signals to obtain corresponding analysis results; The hidden danger locating unit is used to locate hidden danger defects according to the difference between the analysis result corresponding to the impedance spectrum of the healthy state and the analysis result corresponding to the impedance spectrum of the current operating state.

8. The device according to claim 7, characterized in that The reference pseudo frequency calculation unit is used to calculate the reference pseudo frequency according to the following formula: f0=2*sqrt(epsilon) / (c*N0) Where epsilon is the relative dielectric constant of the main insulation layer of the cable to be tested, c is the speed of light, and N0 is the number of data points analyzed per meter.

9. The device according to claim 8, characterized in that The reference frequency list calculation unit is used to determine the reference frequency list F according to the following formula: F=[l1*N0*f0:f0:l2*N0*f0], Among them, [l1*N0*f0:f0:l2*N0*f0] represents an arithmetic progression from l1*N0*f0 to l2*N0*f0 with a step length of f0, where l1 and l2 are the starting point and end point of the positioning interval to be analyzed, and f0 is the reference pseudo frequency.

10. The device according to claim 7, characterized in that The digital lock-in amplifier algorithm analysis unit is used to: for the i-th data point to be analyzed, Select cos(w i t) is used as the first reference signal, multiplied by the current input impedance spectrum and filtered through a low pass filter to obtain the X component, w i is the i-th frequency in the reference frequency list; Select sin(w i t) as a second reference signal, multiplied with the impedance spectrum of the current input and obtained by low-pass filtering the Y component; According to the X and / or Y components, the analysis result corresponding to the i-th data point to be analyzed is obtained.

11. An electronic device, characterized in that: The device comprises a memory and a processor, wherein the memory is used to store computer instructions executable on the processor, and the processor is used to implement the method according to any one of claims 1 to 6 when executing the computer instructions.

12. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method according to any one of claims 1 to 6 is implemented.

Images