Rapid dielectric spectrum testing method and system under combined chirp excitation and storage medium

Abstract

The invention discloses a rapid dielectric spectrum test method and system under combined chirp excitation and a storage medium, and the method comprises the steps: generating a combined chirp excitation signal composed of high-to-low logarithmic sweep frequency chirp waves and low-to-high logarithmic sweep frequency chirp waves, and applying the combined chirp excitation signal to two ends of a test object, excitation voltage signals and response current time domain signals flowing through the test object are synchronously collected, frequency domain analysis is carried out, and complex capacitance corresponding to each pseudo frequency in the two frequency sweeping modes is calculated; arithmetic mean values of the real part and the imaginary part of the complex capacitor with the same pseudo frequency under the two frequency sweeping modes are respectively taken as initial values of the complex capacitor under the pseudo frequency, and a relation curve of the real part, the imaginary part and the pseudo frequency of the complex capacitor is established; and based on a preset dielectric relaxation physical model, performing parameter regression fitting on the relation curve, and evaluating a parameter error in combination with a self-consistent degree to obtain a complex capacitance spectrum test result in a test pseudo-frequency range. The test error can be effectively reduced, the test time can be effectively shortened, and the test efficiency and precision can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of dielectric spectrum testing, and in particular to a fast dielectric spectrum testing method, system and storage medium under combined chirp excitation. Background Art

[0002] Dielectric spectrum, as an effective tool to reveal the dielectric relaxation behavior and characteristics of substances under the action of an electric field, has been widely applied in the fields of scientific research and engineering technology. The standard dielectric spectrum testing technology uses a pure sine wave voltage as the excitation, takes the steady-state response current flowing through the test object as the analysis object, takes the parallel resistor-capacitor equivalent circuit as the analysis model, and realizes the measurement of complex capacitance through digital or hardware phase-locked technology. The spectrum diagram of the real part and the imaginary part of the complex capacitance changing with the excitation voltage frequency is the dielectric spectrum. In the engineering field of power equipment insulation condition diagnosis and the study of dielectric mechanism of non-linear dielectrics, the dielectric response behavior of the research object in the low-frequency band is the most concerned by researchers. The standard low-frequency dielectric spectrum test is very time-consuming. In order to promote the application of low-frequency dielectric spectrum in power equipment insulation diagnosis, a variety of fast dielectric spectrum testing technologies have been proposed. Among them, the fast dielectric spectrum testing technology based on logarithmic chirp excitation saves the most test time.

[0003] Accelerating dielectric spectrum measurement based on logarithmic chirp excitation belongs to non-standard dielectric spectrum testing technology. Its advantage is saving test time, and the disadvantage is that there is a certain error between the test result and the standard test result. The reason for the error lies in the relaxation response of the relaxation polarization of the measured object under non-steady-state excitation. Despite the error problem, under the premise of giving priority to test efficiency, the logarithmic chirp excitation dielectric spectrum testing technology has still been applied in engineering and scientific research. When using the logarithmic chirp fast dielectric spectrum testing technology for insulation diagnosis on site, it is restricted by on-site conditions and unable to evaluate the test error. At the same time, on-site insulation diagnosis also expects a faster and more accurate dielectric spectrum testing technology. The chirp excitation dielectric spectrum uses a time-varying frequency excitation to replace the fixed-frequency standard sine wave excitation. The current flowing through the test sample with a relaxation dielectric response simply does not have a steady state. It is obviously unreasonable to still use the parallel resistor-capacitor equivalent circuit as the analysis model for the research object. This unreasonableness will inevitably lead to a deviation between the chirp excitation dielectric spectrum and the standard dielectric spectrum, and this error is related to the chirp excitation scanning process and the dielectric relaxation characteristics of the measured object. For a specific test object, under the condition of determining the scanning frequency range, extending the scanning time can reduce the test error, but excessively extending the test scanning time goes against the original intention of the fast dielectric spectrum testing technology. Therefore, it is of great practical significance to find other new methods to reduce the test error besides controlling the scanning time. Summary of the Invention

[0004] The object of the present invention is to provide a method, a system and a storage medium for rapid dielectric spectrum testing under combined chirp excitation, which solve the problems of long on-site testing time for low-frequency dielectric spectrum and inability to evaluate the rapid dielectric spectrum testing error during on-site insulation diagnosis in the prior art, can effectively reduce the testing error, shorten the testing time and improve the testing accuracy.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A method for rapid dielectric spectrum testing under combined chirp excitation, the method comprising the following steps:

[0007] S1, generating a combined chirp excitation signal composed of a logarithmically swept chirp wave from high to low and a logarithmically swept chirp wave from low to high, wherein the two chirp waves are symmetric about the origin at the time-domain connection point;

[0008] S2, applying the combined chirp excitation signal to both ends of the test sample, and synchronously collecting the excitation voltage signal and the time-domain signal of the response current flowing through the test sample;

[0009] S3, performing frequency-domain analysis on the excitation voltage signal and the time-domain signal of the response current, and respectively calculating the complex capacitance corresponding to each pseudo-frequency in the logarithmically swept frequency manner from high to low and the logarithmically swept frequency manner from low to high;

[0010] S4, respectively taking the arithmetic mean of the real part and the imaginary part of the complex capacitance with the same pseudo-frequency in the two swept-frequency manners as the initial value of the complex capacitance at this pseudo-frequency, and establishing a relationship curve between the real part, the imaginary part of the complex capacitance and the pseudo-frequency;

[0011] S5, based on a preset dielectric relaxation physical model, performing parameter regression fitting on the relationship curve, evaluating the parameter error with the self-consistency degree between the fitting model parameters of the real and imaginary parts of the complex capacitance, and obtaining the complex capacitance spectrum test result within the test pseudo-frequency range.

[0012] Further, in the S1, the time-domain connection point means that the time-domain end point of the chirp wave of the first swept-frequency manner is used as the starting point of the chirp wave of the second swept-frequency manner, and after the docking of the two swept-frequency manners, the subsequent sweeping starts in the form of symmetry about the origin at the time-domain connection point, wherein the phases and amplitudes of the two chirp waves satisfy the symmetry relationship about the origin at the connection point.

[0013] Further, the swept-frequency range of the combined chirp excitation signal is 1 mHz to 1000 Hz, which is applicable to the insulation state diagnosis of electrical equipment or the research on the dielectric properties and mechanisms of non-linear insulating media.

[0014] Further, in the S3, performing frequency-domain analysis on the excitation voltage signal and the time-domain signal of the response current, and respectively calculating the complex capacitance corresponding to each pseudo-frequency in the logarithmically swept frequency manner from high to low and the logarithmically swept frequency manner from low to high, specifically including:

[0015] The digital phase-locked technology is adopted to demodulate the excitation voltage signal and the response current time-domain signal, extract the fundamental component amplitudes and phases at each pseudo-frequency, and calculate the test values of the real and imaginary parts of the complex capacitance corresponding to each pseudo-frequency in the logarithmic sweep frequency mode from high to low and from low to high respectively.

[0016] Further, in step S5, based on a preset dielectric relaxation physical model, parameter regression fitting is performed on the relationship curve to obtain the complex capacitance spectrum test results within the test pseudo-frequency range, specifically including:

[0017] Based on the extended Debye relaxation physical model, parameter fitting of the relaxation polarization physical model is performed on the relationship curves of the real and imaginary parts of the complex capacitance and the pseudo-frequency, and the fitting model parameters of the real and imaginary parts are obtained respectively;

[0018] Taking the self-consistency degree between the fitting model parameters of the real and imaginary parts as a limiting condition, the abnormal test data with excessive complex capacitance errors is eliminated;

[0019] If the self-consistency degree between the fitting model parameters of the real and imaginary parts meets the set conditions, the mean values of the fitting model parameters of the real and imaginary parts are used as the model parameters and substituted into the extended Debye relaxation physical model to calculate the complex capacitance spectrum test results within the test pseudo-frequency range.

[0020] Further, the calculation formula for the self-consistency degree SC between the fitting model parameters of the real and imaginary parts is expressed as:

[0021]

[0022] where the capacitance parameter C s,fitr and the time constant τ s,fitr are obtained from the real part of the complex capacitance, and the capacitance parameter C s,fiti and the time constant τ s,fiti are obtained from the imaginary part of the complex capacitance;

[0023] If the electrical parameters in the extended Debye relaxation physical model include capacitance, resistance, and time constant, and each parameter has N, the parameters obtained from the real part of the complex capacitance are the capacitance parameter C i,fitr , the resistance parameter R i,fitr and the time constant τ i,fitr , and the parameters obtained from the imaginary part of the complex capacitance are the capacitance parameter C i,fiti , the resistance parameter R i,fiti and the time constant τ i,fiti , where i = 1, 2,..., N, then the above formula is rewritten as:

[0024]

[0025] The present invention also provides a fast dielectric spectrum testing system under combined chirp excitation for implementing the fast dielectric spectrum testing method under combined chirp excitation as described above, including:

[0026] A combined chirp excitation signal generation module for generating a combined chirp excitation signal composed of a logarithmically swept chirp wave from high to low and a logarithmically swept chirp wave from low to high, wherein the two chirp waves are symmetric about the origin at the time domain connection point;

[0027] A signal acquisition module for applying the combined chirp excitation signal to both ends of the specimen and synchronously acquiring the excitation voltage signal and the time domain signal of the response current flowing through the specimen;

[0028] A complex capacitance calculation module for performing frequency domain analysis on the excitation voltage signal and the time domain signal of the response current, and respectively calculating the complex capacitance corresponding to each pseudo-frequency in the logarithmically swept frequency manner from high to low and in the logarithmically swept frequency manner from low to high;

[0029] A relationship curve establishment module for respectively taking the arithmetic mean of the real part and the imaginary part of the complex capacitance at the same pseudo-frequency in the two swept frequency modes as the initial value of the complex capacitance at this pseudo-frequency, and establishing a relationship curve between the real part, the imaginary part of the complex capacitance and the pseudo-frequency;

[0030] A test result generation module for performing parameter regression fitting on the relationship curve based on a preset dielectric relaxation physical model, evaluating the parameter error with the degree of self-consistency between the fitting model parameters of the real and imaginary parts of the complex capacitance, and obtaining the complex capacitance spectrum test result within the test pseudo-frequency range.

[0031] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein when the processor executes the computer program, the fast dielectric spectrum testing method under combined chirp excitation as described above is implemented.

[0032] The present invention also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed, the fast dielectric spectrum testing method under combined chirp excitation as described above is implemented.

[0033] According to the specific embodiments provided by the present invention, the following technical effects are disclosed by the present invention:

[0034] First, two chirp waveforms with logarithmic frequency sweeps from high to low and from low to high are adopted, and they are combined into an excitation waveform in the form of symmetry about the origin at the connection point. The response current flowing through the specimen is tested and analyzed to obtain the complex capacitance at different pseudo-frequencies. Then, the mean value of the complex capacitances at the same pseudo-frequency under the two frequency sweep methods is taken as the initial value. Since the waveform characteristics of the two logarithmic frequency sweep methods from high to low and from low to high are opposite, the corresponding error polarities of the measured complex capacitance (real part, imaginary part) are also just opposite. By means of mean value operation, the test error of the complex capacitance at the pseudo-frequency will be reduced.

[0035] After that, based on the extended Debye relaxation model, the physical model parameters of the relaxation polarization are respectively fitted for the curves of the real part and the imaginary part of the complex capacitance versus the pseudo-frequency. The self-consistency degree between the fitted model parameters of the real and imaginary parts of the complex capacitance is used as an index to evaluate the parameter error. When the requirement of self-consistency degree is met, the mean value of the fitted model parameters is used as the calculation basis to obtain the complex capacitance result within the test frequency range. The self-consistency degree between the parameters after fitting the physical models of the real part and the imaginary part of the complex capacitance is used to evaluate the test error of the logarithmic chirp excitation fast dielectric spectroscopy, which solves the problem that the logarithmic chirp fast dielectric spectroscopy test technology cannot judge the error in on-site insulation diagnosis applications, improves the test efficiency and accuracy of the logarithmic chirp fast dielectric spectroscopy, and will be conducive to promoting the wider application of the logarithmic chirp fast dielectric spectroscopy test technology. Brief Description of the Drawings

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0037] Figure 1 It is a flowchart of the fast dielectric spectroscopy test method under combined chirp excitation in the embodiment of the present invention;

[0038] Figure 2 It is a model diagram of a resistor-capacitor parallel circuit without relaxation characteristics in the embodiment of the present invention;

[0039] Figure 3 It is a schematic diagram of the time-domain waveforms of the chirp wave excitation voltage and its response current in the embodiment of the present invention. Among them, (a) represents the time-domain waveform of the simulated excitation voltage, and (b) represents the time-domain waveform of the response current;

[0040] Figure 4Schematic diagram of the comparison between the non-relaxation polarization complex capacitance (real part, imaginary part) and the theoretical value in the embodiments of the present invention. Among them, (a) shows the variation law of the real part C′ of the complex capacitance with frequency, (b) shows the relative error between the digital phase-locked result of the real part of the complex capacitance and the theoretical true value, (c) shows the variation law of the imaginary part C″ of the complex capacitance with frequency, and (d) shows the relative error between the digital phase-locked result of the imaginary part of the complex capacitance and the theoretical true value.

[0041] Figure 5 Schematic diagram of the time-domain waveform of the chirp wave excitation voltage with the origin symmetry combination of the connection points in the embodiments of the present invention;

[0042] Figure 6 Circuit model diagram of two relaxation mechanisms connected in series and then in parallel in the embodiments of the present invention;

[0043] Figure 7 Time-domain waveform diagram of the total response current of the double series branches under the combined chirp excitation in the embodiments of the present invention;

[0044] Figure 8 Schematic diagram of the comparison between the single chirp scan digital phase-locked result and its relative error in the embodiments of the present invention. Among them, (a) shows the variation law of the real part C′ of the complex capacitance with frequency, (b) shows the relative error between the digital phase-locked result of the real part of the complex capacitance and the theoretical true value, (c) shows the variation law of the imaginary part C″ of the complex capacitance with frequency, and (d) shows the relative error between the digital phase-locked result of the imaginary part of the complex capacitance and the theoretical true value;

[0045] Figure 9 Schematic diagram of the comparison between the new technology and the traditional technology in terms of dielectric spectrum and relative error with different scan times in the embodiments of the present invention. Among them, (a) is the relative error of the real part C′ of the complex capacitance, and (b) is the relative error of the imaginary part C″ of the complex capacitance. Detailed implementation manners

[0046] The embodiments of the present invention will be described in detail below. The embodiments are intended to explain the present invention and should not be construed as limiting the present invention. For those without specific technologies or conditions indicated in the embodiments, they shall be carried out according to the technologies or conditions described in the literature in the field or according to the product specifications. For the reagents or instruments without the manufacturer indicated, they are all conventional products that can be obtained through commercial procurement.

[0047] The combined chirp excitation-based fast dielectric spectrum testing method and system provided by the present invention can reduce the testing error, shorten the testing time, improve the testing efficiency and accuracy of the fast dielectric spectrum under chirp excitation, and promote the application of the logarithmic chirp dielectric spectrum testing technology in the fields of on-site insulation diagnosis and research on the dielectric properties and mechanisms of non-linear insulating media.

[0048] Embodiment 1

[0049] As Figure 1As shown in the figure, the method for rapid dielectric spectrum testing under combined chirp excitation provided by the present invention includes the following steps:

[0050] S1, generating a combined chirp excitation signal composed of a logarithmically swept chirp wave from high to low and a logarithmically swept chirp wave from low to high, wherein the two chirp waves are symmetric about the origin at the time-domain connection point;

[0051] Among them, the time-domain connection point refers to the end point of the time domain of the chirp wave of the first frequency-sweeping method as the starting point of the chirp wave of the second frequency-sweeping method. After the two frequency-sweeping methods are docked, the subsequent frequency sweeping starts in the form of symmetry about the origin at the time-domain connection point. Among them, the first frequency-sweeping method is one of the two logarithmically swept frequency-sweeping methods from high to low and from low to high, then the second frequency-sweeping method is the other of the two logarithmically swept frequency-sweeping methods. The logarithmically swept chirp wave from high to low and the logarithmically swept chirp wave from low to high respectively correspond to the logarithmically swept frequency-sweeping method from high to low and the logarithmically swept frequency-sweeping method from low to high. Specifically, the time-domain connection point refers to the end point of the time domain of the logarithmically swept chirp wave from high to low as the starting point of the logarithmically swept chirp wave from low to high, and the phases and amplitudes of the two chirp waves satisfy the origin-symmetry relationship at the connection point; the frequency-sweeping range of the combined chirp excitation signal is 1 mHz to 1000 Hz, which is applicable to the diagnosis of the insulation state of electrical equipment or the study of the dielectric properties and mechanisms of non-linear insulating media;

[0052] S2, applying the combined chirp excitation signal to both ends of the test sample, and synchronously collecting the excitation voltage signal and the time-domain signal of the response current flowing through the test sample;

[0053] S3, performing frequency-domain analysis on the excitation voltage signal and the time-domain signal of the response current, and respectively calculating the complex capacitance corresponding to each pseudo-frequency under the logarithmically swept frequency-sweeping method from high to low and the logarithmically swept frequency-sweeping method from low to high; specifically including:

[0054] Using digital phase-locked technology to demodulate the excitation voltage signal and the time-domain signal of the response current, extracting the fundamental component amplitude and phase at each pseudo-frequency, and respectively calculating the test values of the real part and the imaginary part of the complex capacitance corresponding to each pseudo-frequency under the logarithmically swept frequency-sweeping method from high to low and the logarithmically swept frequency-sweeping method from low to high;

[0055] S4, taking the arithmetic mean of the real part and the imaginary part of the complex capacitance at the same pseudo-frequency under the two frequency-sweeping methods as the initial value of the complex capacitance at this pseudo-frequency, and establishing a relationship curve between the real part and the imaginary part of the complex capacitance and the pseudo-frequency;

[0056] S5, based on a preset dielectric relaxation physical model, performing parameter regression fitting on the relationship curve, and using the degree of self-consistency between the fitting model parameters of the real and imaginary parts of the complex capacitance as an index to evaluate the parameter error, and obtaining the complex capacitance spectrum test result within the test pseudo-frequency range; specifically including:

[0057] Based on the extended Debye relaxation physical model, the relationship curves of the real part, imaginary part of the complex capacitance and the pseudo-frequency are fitted with the parameters of the relaxation polarization physical model, and the fitting model parameters of the real part and the imaginary part are obtained respectively;

[0058] Taking the consistency degree between the fitting model parameters of the real part and the imaginary part as the limiting condition, the abnormal test data with too large complex capacitance error are eliminated;

[0059] If the consistency degree between the fitting model parameters of the real part and the imaginary part meets the set conditions, the mean value of the fitting model parameters of the real part and the imaginary part is used as the model parameter to be substituted into the extended Debye relaxation physical model to calculate the complex capacitance spectrum test results within the test pseudo-frequency range.

[0060] Among them, the specific description of the consistency degree SC between the fitting model parameters of the real part and the imaginary part is as follows:

[0061] When using the parallel resistor-capacitor circuit model without relaxation characteristics (the parameters characterizing no relaxation characteristics are capacitance C s and time constant τ s ), the above digital phase-locked technology obtains the mean value of the complex capacitance at different pseudo-frequencies, and respectively fits the relationship curves of the real part, imaginary part of the complex capacitance and the pseudo-frequency. The capacitance parameter C s,fitr and time constant τ s,fitr are obtained from the real part of the complex capacitance, and the capacitance parameter C s,fiti and time constant τ s,fiti are obtained from the imaginary part of the complex capacitance. Here, the degree of consistency of the parameters obtained by fitting the real part and the imaginary part is expressed by the self-consistency degree, and is defined as:

[0062]

[0063] Considering the general case, when there are electrical parameters such as capacitance C i , resistance R i and time constant τ i in the extended Debye relaxation physical model, and there are N of each parameter. The parameters obtained from the real part of the complex capacitance are capacitance parameter C i,fitr , resistance parameter R i,fitr and time constant τ i,fitr , and the parameters obtained from the imaginary part of the complex capacitance are capacitance parameter C i,fiti , resistance parameter R i,fiti and time constant τ i,fiti , where i = 1, 2,..., N, then the above formula is rewritten as:

[0064]

[0065] The present invention verifies the existing fast dielectric spectrum test method under logarithmic chirp excitation and the fast dielectric spectrum test method under combined chirp excitation provided by the present invention through simulation analysis:

[0066] I. Verification of the Fast Dielectric Spectrum Testing Method under Logarithmic Chirp Excitation

[0067] In this embodiment, a simulation model is established on the Simulink platform in MATLAB. The response current of the object under test is obtained through simulation under a given chirp wave excitation voltage. Then, the digital phase-locked technology is used to obtain the variation laws of the real and imaginary parts of the complex capacitance with the pseudo-frequency, that is, the so-called dielectric spectrum. Both the simulation and the digital phase-locking can be implemented by existing technologies and will not be elaborated here.

[0068] For the object under test without relaxation polarization behavior, the dielectric spectrum measured by chirp excitation should be the same as the result of the standard dielectric spectrum test. To verify the correctness of the simulation modeling and the digital phase-locking algorithm, a resistor-capacitor parallel circuit model without relaxation characteristics (as shown in Figure 2 ) is simulated. The circuit parameters are set as follows: capacitance C p = 200 nF, conductance G p = 0.5 nS.

[0069] The time-domain signal of the logarithmic chirp wave excitation voltage is as follows:

[0070]

[0071] where t is the time parameter; t ch is the end time of the chirp wave in the form of logarithmic frequency sweep from high to low, which can also be called the frequency sweep time; f0 is the starting pseudo-frequency; f1 is the cut-off pseudo-frequency of the chirp wave; A is the peak value of the chirp wave excitation voltage. The specific simulation conditions are: A = 200 V, f0 = 1 Hz, f1 = 1 mHz, t ch = 1800 s, and the simulation step size is 0.001 s. The time-domain waveforms of the simulation excitation voltage and the response current are as shown in Figure 3 . When calculating the error, the theoretical values of the real part C′ and the imaginary part C″ of the complex capacitance are calculated according to the following formula.

[0072]

[0073] where f is the pseudo-frequency, and the pseudo-frequency refers to the equivalent standard sine wave frequency.

[0074] Within each pseudo-period, the digital phase-locking of the response current signal is performed with the chirp wave excitation voltage signal as the reference, and the variation law of the phase-locked result of the equivalent complex capacitance of the resistor-capacitor parallel circuit obtained by simulation with frequency is obtained. As shown in Figure 4 , where Figure 4 (a) shows the variation law of the real part C′ of the complex capacitance with frequency, Figure 4 (b) shows the relative error between the digital phase-locked result of the real part of the complex capacitance and the theoretical true value, Figure 4 (c) shows the variation law of the imaginary part C″ of the complex capacitance with frequency,Figure 4 In (d), it represents the relative error between the imaginary part digital phase-locked result of the complex capacitance and the theoretical true value.

[0075] Figure 4 The results intuitively show that for the tested products without relaxation polarization behavior, the dielectric spectra obtained by chirp excitation are exactly the same as those measured by the standard sine wave, that is, there is no systematic test error. The error data presented in the high-frequency band are model errors formed because the sampling rate does not strictly satisfy the Shannon law, and the error amplitude is within ±2‰.

[0076] II. Verification of the fast dielectric spectrum testing method under the combined chirp excitation provided by the present invention

[0077] The excitation voltage of the origin-symmetric combined chirp wave at the connection point can be expressed by the following formula:

[0078]

[0079] In the above formula, when t is less than t ch , the chirp waveform is a frequency sweep form from high to low. When t is greater than t ch , the chirp waveform is a logarithmic frequency sweep form from low to high. The total scanning time of the entire combined chirp is 2t ch -Δt; t ch is the connection time point of the chirp wave in two forms: logarithmic frequency sweep from high to low and logarithmic frequency sweep from low to high of the combined chirp wave; f0 is the starting pseudo-frequency; f1 is the cut-off pseudo-frequency of the chirp wave; Δt is the sampling step of digital measurement.

[0080] The connection time point t ch should satisfy an integer multiple of Δt. At the same time, to ensure origin symmetry at the connection point, t ch should also satisfy the following formula:

[0081]

[0082] In the formula, M is a positive integer and is also the number of pseudo-periods of the previous and the subsequent logarithmic frequency sweep processes. If the initially selected t ch does not meet the condition that M is a positive integer, the sweep time t ch should be adjusted. The specific adjustment method is as follows: round up the calculated M value according to the above formula, recalculate to obtain t end , and use t end to replace t ch . The adjustment process can be realized by computer programming. The combined chirp ensures origin symmetry to guarantee that the first derivative of the excitation voltage waveform is continuous in the time domain, and the corresponding response current signal will not mutate. A typical combined chirp signal is as shown in Figure 5 .

[0083] The combined chirp wave is used as an excitation to test the DUT to obtain the time-domain digital signal of the response current flowing through the test product. The combined chirp wave voltage signal is used as a reference to digitally phase-lock the response current signal in each pseudo-cycle, and the test values ​​of the real and imaginary parts of the complex capacitance are calculated based on this. The two complex capacitance results of different sweep modes and the same pseudo-cycle are averaged to obtain the curves of the real and imaginary parts of the complex capacitance changing with the pseudo-frequency.

[0084] For the above-mentioned mean values ​​of complex capacitance under different pseudofrequencies, curve fitting is performed on the real and imaginary parts of the complex capacitance respectively, and the parameter obtained from the real part of the complex capacitance is the capacitance parameter C s,fitr and the time constant τ s,fitr , the parameter obtained from the imaginary part of the complex capacitance is the capacitance parameter C s,fiti and the time constant τ s,fiti Here, the consistency of the parameters obtained by fitting the real and imaginary parts is expressed by self-consistency, which is defined as:

[0085]

[0086] If the self-consistency of the model parameters meets the requirements, the real and imaginary fitting parameters can be averaged as the parameters of the relaxation polarization physical model, and finally the mean parameters can be brought into the relaxation polarization model to calculate the curve of the change of complex capacitance with frequency, which is used as the test result of the final combined chirp excitation fast dielectric spectrum test technology. If the self-consistency of the model parameters is low, it means that the test results after averaging have large errors in individual tests. In this case, the test points and model regression residuals can be analyzed, and the statistical Laida criterion can be used to eliminate abnormal data points with large errors, and then the model parameters can be regressed. Repeat the above process until the self-consistency of the model parameters meets the set conditions.

[0087] In order to verify the effectiveness of the new fast dielectric spectrum test technology of origin symmetrical combined chirp excitation at the connection point in reducing test errors and saving test time, a circuit model of two series-connected and then parallel-connected circuits equivalent to two relaxation mechanisms was established (such as Figure 6 The parameters of series circuit 1 are set as follows: Capacitor C s1 =0.2nF, resistor R s1 =20TΩ(corresponding to equivalent relaxation polarization response time τ1=C s1 R s1 =400s); the parameters of the series equivalent circuit 2 are set as: capacitor C s2 =0.1nF, resistor R s2 =10TΩ(corresponding to equivalent relaxation polarization response time τ2=C s2 R s2= 100 s). In the confirmatory simulation study, the reason for adopting the double series equivalent circuit model instead of the single series circuit model is to consider the factors of the extended Debye model widely used in engineering insulation diagnosis. Through simulation, the typical time-domain waveform of the total response current of the double series branches is obtained as Figure 7 shown.

[0088] To provide a comparison benchmark, first, the traditional logarithmic chirp excitation fast dielectric frequency spectrum technology is used to simulate the double series branches under the conditions that the chirp excitation frequency sweep range is 1 mHz - 1 Hz and the frequency sweep time reaches 10,000 s, and the variation law of the complex capacitance with frequency and the test error are obtained as Figure 8 shown, where Figure 8 (a) in shows the variation law of the real part C′ of the complex capacitance with frequency, Figure 8 (b) in shows the relative error between the digital phase-locked result of the real part of the complex capacitance and the theoretical true value, Figure 8 (c) in shows the variation law of the imaginary part C″ of the complex capacitance with frequency, Figure 8 (d) in shows the relative error between the digital phase-locked result of the imaginary part of the complex capacitance and the theoretical true value.

[0089] From Figure 8 (b), it can be seen that the maximum error of the real part is 0.403% at low frequency and -2.983% at high frequency; from Figure 8 (d), it can be seen that the maximum error of the imaginary part is 4.766% at low frequency and -2.308% at high frequency.

[0090] To verify the efficacy of the new test technology of the fast dielectric frequency spectrum based on the origin-symmetric combined chirp excitation at the connection point in suppressing test errors and saving test time, the new technology is simulated for the double series circuit model under four conditions where the total scanning duration is 1,000 s, 1,200 s, 2,400 s, and 3,600 s respectively, and the results of the complex capacitance and the error obtained by phase-locking are as Figure 9 shown. For easy comparison, the simulation results of the traditional chirp excitation test technology are also plotted in Figure 9 .

[0091] Figure 9 For the comparison of the dielectric frequency spectrum and the relative error between the new technology and the traditional technology, Figure 9 (a) in is the relative error of the real part C′, Figure 9 (b) in is the relative error of the imaginary part C″.

[0092] When calculating the error, the theoretical value is obtained by calculating according to the following formula:

[0093]

[0094] From Figure 9It can be seen that the test error of the new technology for fast dielectric spectrum testing with combined chirp excitation also decreases as the total scanning time increases; even under the condition of the shortest scanning duration (1000 s), the error corresponding to the new technology is smaller than the error corresponding to the traditional single chirp excitation testing technology when the scanning time is 10,000 s. This simulation result fully demonstrates the significant efficacy of the new technology in suppressing test errors and saving test time compared with the existing single chirp excitation fast dielectric spectrum testing technology.

[0095] Embodiment 2

[0096] The present invention also provides a fast dielectric spectrum testing system under combined chirp excitation for performing the fast dielectric spectrum testing method under combined chirp excitation as described above, including:

[0097] A combined chirp excitation signal generation module for generating a combined chirp excitation signal composed of a logarithmically swept chirp wave from high to low and a logarithmically swept chirp wave from low to high, wherein the two chirp waves are symmetric about the origin at the time domain connection point;

[0098] A signal acquisition module for applying the combined chirp excitation signal to both ends of the test sample and synchronously acquiring the excitation voltage signal and the time domain signal of the response current flowing through the test sample;

[0099] A complex capacitance calculation module for performing frequency domain analysis on the excitation voltage signal and the time domain signal of the response current, and respectively calculating the complex capacitance corresponding to each pseudo-frequency in the logarithmically swept frequency manner from high to low and the logarithmically swept frequency manner from low to high;

[0100] A relationship curve establishment module for respectively taking the arithmetic mean of the real part and the imaginary part of the complex capacitance with the same pseudo-frequency in the two swept frequency manners as the initial value of the complex capacitance at this pseudo-frequency, and establishing a relationship curve between the real part, the imaginary part of the complex capacitance and the pseudo-frequency;

[0101] A test result generation module for performing parameter regression fitting on the relationship curve based on a preset dielectric relaxation physical model, evaluating the parameter error with the self-consistency degree between the fitting model parameters of the real and imaginary parts of the complex capacitance as an index, and obtaining the complex capacitance spectrum test result within the test pseudo-frequency range.

[0102] Regarding the system in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment related to the method, and will not be elaborated here in detail.

[0103] In addition, the present invention also provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, and when the processor executes the computer program, it implements the fast dielectric spectrum testing method under combined chirp excitation as described above.

[0104] The processor can be a Central Processing Unit (CPU), or it can be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor, etc.

[0105] The memory can include various types of storage units, such as system memory, read-only memory (ROM), and permanent storage devices. Among them, the ROM can store static data or instructions required by the processor or other modules of the computer. The permanent storage device can be a readable and writable storage device. The permanent storage device can be a non-volatile storage device that does not lose the stored instructions and data even when the computer is powered off. In some embodiments, the permanent storage device uses a mass storage device (such as a magnetic or optical disk, flash memory) as the permanent storage device. In some other embodiments, the permanent storage device can be a removable storage device (such as a floppy disk, optical drive). The system memory can be a readable and writable storage device or a volatile readable and writable storage device, such as dynamic random access memory. The system memory can store some or all of the instructions and data required by the processor during operation. In addition, the memory can include any combination of computer-readable storage media, including various types of semiconductor storage chips (such as DRAM, SRAM, SDRAM, flash memory, programmable read-only memory), and magnetic disks and / or optical disks can also be used. In some embodiments, the memory can include a removable storage device that is readable and / or writable, such as a compact disc (CD), read-only digital versatile disc (such as DVD-ROM, dual-layer DVD-ROM), read-only Blu-ray disc, ultra density optical disc, flash memory card (such as SD card, min SD card, Micro-SD card, etc.), magnetic floppy disk, etc. The computer-readable storage medium does not include carrier waves and instantaneous electronic signals transmitted wirelessly or by wire.

[0106] An executable code is stored on the memory. When the executable code is processed by the processor, it can cause the processor to execute some or all of the combined chirp excitation-based fast dielectric spectroscopy test methods described above.

[0107] In addition, the method according to the present invention can also be implemented as a computer program or a computer program product, which includes computer program code instructions for performing some or all of the steps in the above-mentioned rapid dielectric spectroscopy testing method under combined chirp excitation of the present invention.

[0108] Alternatively, the present invention can also be implemented as a computer-readable storage medium (or non-transitory machine-readable storage medium or machine-readable storage medium) on which executable code (or computer program or computer instruction code) is stored. When the executable code (or computer program or computer instruction code) is executed by a processor of an electronic device (or a server, etc.), the processor is caused to execute some or all of the steps of the above-mentioned rapid dielectric spectroscopy testing method under combined chirp excitation of the present invention.

[0109] Matters not described in the present invention are well-known techniques.

[0110] The various embodiments of the present invention have been described above. The above description is exemplary and not exhaustive, and is also not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art in the technical field without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technologies in the market, or to enable other ordinary skill in the art in the technical field to understand the disclosed embodiments.

Claims

1. A fast dielectric spectrum testing method under combined chirp excitation, characterized in that It includes the following steps: S1. Generate a combined chirp excitation signal composed of a logarithmically swept chirp wave from high to low and a logarithmically swept chirp wave from low to high. Among them, the two chirp waves are symmetric about the origin at the time-domain connection point; S2. Apply the combined chirp excitation signal to both ends of the specimen, and synchronously collect the excitation voltage signal and the time-domain signal of the response current flowing through the specimen; S3. Perform frequency-domain analysis on the excitation voltage signal and the time-domain signal of the response current, and calculate the complex capacitance corresponding to each pseudo-frequency in the logarithmically swept frequency mode from high to low and the logarithmically swept frequency mode from low to high respectively; S4. Take the arithmetic mean of the real part and the imaginary part of the complex capacitance with the same pseudo-frequency in the two swept-frequency modes as the initial value of the complex capacitance at this pseudo-frequency, and establish a relationship curve between the real part, the imaginary part of the complex capacitance and the pseudo-frequency; S5. Based on a preset dielectric relaxation physical model, perform parameter regression fitting on the relationship curve, and use the degree of self-consistency between the fitting model parameters of the real and imaginary parts of the complex capacitance as an index to evaluate the parameter error, and obtain the complex capacitance spectrum test result within the test pseudo-frequency range.

2. The rapid dielectric spectrum testing method under combined chirp excitation according to claim 1, characterized in that In S1, the time-domain connection point refers to the end point of the time domain of the chirp wave in the first swept-frequency mode as the starting point of the chirp wave in the second swept-frequency mode. After the two swept-frequency modes are connected, subsequent sweeping starts in the form of symmetry about the origin at the time-domain connection point. Among them, the phases and amplitudes of the two chirp waves satisfy the symmetry relationship about the origin at the connection point.

3. The rapid dielectric spectrum testing method under combined chirp excitation according to claim 1, characterized in that The swept-frequency range of the combined chirp excitation signal is 1 mHz to 1000 Hz, which is applicable to the diagnosis of the insulation state of electrical equipment or the research on the dielectric properties and mechanisms of non-linear insulating media.

4. The rapid dielectric spectrum testing method under combined chirp excitation according to claim 1, wherein In S3, perform frequency-domain analysis on the excitation voltage signal and the time-domain signal of the response current, and calculate the complex capacitance corresponding to each pseudo-frequency in the logarithmically swept frequency mode from high to low and the logarithmically swept frequency mode from low to high respectively. Specifically, it includes: Use digital phase-locked technology to demodulate the excitation voltage signal and the time-domain signal of the response current, extract the fundamental component amplitudes and phases at each pseudo-frequency, and calculate the test values of the real part and the imaginary part of the complex capacitance corresponding to each pseudo-frequency in the logarithmically swept frequency mode from high to low and the logarithmically swept frequency mode from low to high respectively.

5. The rapid dielectric spectrum testing method under combined chirp excitation according to claim 1, wherein In S5, based on a preset dielectric relaxation physical model, perform parameter regression fitting on the relationship curve, and use the degree of self-consistency between the fitting model parameters of the real and imaginary parts of the complex capacitance as an index to evaluate the parameter error, and obtain the complex capacitance spectrum test result within the test pseudo-frequency range. Specifically, it includes: Based on the extended Debye relaxation physical model, perform fitting of the relaxation polarization physical model parameters on the relationship curve between the real part, the imaginary part of the complex capacitance and the pseudo-frequency, and obtain the fitting model parameters of the real part and the imaginary part respectively; Taking the degree of self-consistency between the fitting model parameters of the real part and the imaginary part as a limiting condition, eliminate the abnormal test data with too large complex capacitance error; If the degree of self-consistency between the fitting model parameters of the real part and the imaginary part meets the set conditions, then use the mean value of the fitting model parameters of the real part and the imaginary part as the model parameters to substitute into the extended Debye relaxation physical model to calculate the complex capacitance spectrum test result within the test pseudo-frequency range.

6. The rapid dielectric spectrum testing method under combined chirp excitation according to claim 5, wherein The calculation formula for the degree of self-consistency SC between the fitting model parameters of the real part and the imaginary part is expressed as: Among them, the capacitance parameter obtained from the real part of the complex capacitance is C s,fitr and the time constant τ s,fitr , and the capacitance parameter obtained from the imaginary part of the complex capacitance is C s,fiti and the time constant τ s,fiti ; If the electrical parameters in the extended Debye relaxation physical model include capacitance, resistance, and time constant, and there are N of each parameter, the parameters obtained from the real part of the complex capacitance are the capacitance parameter C i,fitr , the resistance parameter R i,fitr , and the time constant τ i,fitr . The parameters obtained from the imaginary part of the complex capacitance are the capacitance parameter C i,fiti , the resistance parameter R i,fiti , and the time constant τ i,fiti . Among them, i = 1, 2, …, N, then the above formula is rewritten as:

7. A fast dielectric spectroscopy test system under combined chirp excitation, which is used to perform the fast dielectric spectroscopy test method under combined chirp excitation according to any one of claims 1-6, and is characterized in that It includes: A combined chirp excitation signal generation module is used to generate a combined chirp excitation signal composed of a logarithmically swept chirp wave from high to low and a logarithmically swept chirp wave from low to high. Among them, the two chirp waves are symmetric about the origin at the time-domain connection point; A signal acquisition module is used to apply the combined chirp excitation signal to both ends of the test sample, and synchronously acquire the excitation voltage signal and the time-domain signal of the response current flowing through the test sample; A complex capacitance calculation module is used to perform frequency-domain analysis on the excitation voltage signal and the time-domain signal of the response current, and calculate the complex capacitance corresponding to each pseudo-frequency in the logarithmically swept frequency manner from high to low and from low to high respectively; A relationship curve establishment module is used to respectively take the arithmetic mean of the real part and the imaginary part of the complex capacitance at the same pseudo-frequency under the two swept-frequency modes as the initial value of the complex capacitance at this pseudo-frequency, and establish a relationship curve between the real part, the imaginary part of the complex capacitance and the pseudo-frequency; A test result generation module is used to perform parameter regression fitting on the relationship curve based on a preset dielectric relaxation physical model, evaluate the parameter error with the degree of self-consistency between the fitting model parameters of the real and imaginary parts of the complex capacitance as an index, and obtain the complex capacitance spectrum test result within the test pseudo-frequency range.

8. An electronic device, characterized in that, It includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, it implements the fast dielectric spectrum test method under combined chirp excitation as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, A computer program is stored thereon, and when the computer program is executed, it implements the fast dielectric spectrum test method under combined chirp excitation as described in any one of claims 1 to 6.

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