Time domain and frequency domain equivalent method and system of dielectric response, storage medium and equipment

Abstract

The invention relates to the technical field of dielectric response equivalence, and discloses a time domain and frequency domain equivalence method for dielectric response, and the method comprises the steps: obtaining the frequency domain dielectric spectrum FDS data of an insulating medium; determining related parameters of a medium broadband equivalent model according to the frequency domain dielectric spectrum FDS data; building a corresponding time domain dielectric response equivalent circuit according to the dielectric broadband equivalent model; simulating a polarization depolarization current PDC according to the time domain dielectric response equivalent circuit to obtain a PDC curve; the PDC curve is analyzed, and the equivalent conversion relation between the time domain and the frequency domain of the dielectric response is determined. By establishing the medium broadband equivalent model and the time domain equivalent circuit, equivalent conversion of the frequency domain dielectric spectrum data and the time domain dielectric response is realized, the dynamic behavior of the insulating medium under the action of the electric field can be more intuitively understood, and insulation diagnosis and material performance evaluation of power equipment can be realized.

Description

Technical Field

[0001] The present invention relates to the field of dielectric response equivalent technology, and in particular to a time-domain and frequency-domain equivalent method, system, storage medium and device for dielectric response. Background Art

[0002] In the power system, the performance of insulating materials is a key factor in ensuring the safe and stable operation of power equipment. If the performance of insulating materials deteriorates, it may cause equipment failure or even cause serious power accidents. Therefore, in-depth research and analysis of the dielectric properties of insulating materials can not only help us evaluate the current state of insulating materials, but also predict their aging trends, thereby effectively preventing potential insulation failures. This kind of research plays a vital role in the reliability of power systems and maintenance cost control.

[0003] At present, the polarization / depolarization current (PDC) method commonly used in the technical field can analyze the polarization characteristics of the material in detail, including key parameters such as polarization intensity and polarization time constant, by measuring the polarization and depolarization current of the material under the action of a step voltage. The frequency domain dielectric spectroscopy (FDS) method deeply explores the frequency domain characteristics of the material by measuring the dielectric constant and dielectric loss angle of the material at different frequencies. These two methods provide powerful tools for the diagnosis and evaluation of the insulation status of power equipment from two different perspectives, time domain and frequency domain.

[0004] Although PDC and FDS methods have been widely used in power system insulation diagnosis, they are often relatively independent in actual operation, lacking a systematic framework to analyze the correlation and equivalence between the two methods. This separate analysis method may lead to an incomplete understanding of the performance of insulation materials and limit the ability to fully evaluate the insulation system from a more macro perspective. Therefore, exploring the connection between PDC and FDS methods and developing a systematic method that can combine time domain and frequency domain analysis is of great significance to improve the accuracy and efficiency of insulation condition diagnosis. Summary of the invention

[0005] Based on this, it is necessary to propose a time-domain and frequency-domain equivalent method for dielectric response in view of the lack of a systematic framework to analyze the correlation and equivalence between the PDC and FDS methods.

[0006] A time-domain and frequency-domain equivalent method for dielectric response, the method comprising the following steps:

[0007] Obtain frequency domain dielectric spectrum FDS data of insulating media;

[0008] Determine relevant parameters of the medium broadband equivalent model according to the FDS data;

[0009] According to the broadband equivalent model of the medium, a corresponding time-domain dielectric response equivalent circuit is constructed;

[0010] Simulating the polarization depolarization current PDC according to the time domain dielectric response equivalent circuit to obtain a PDC curve;

[0011] The PDC curve is analyzed to determine the equivalent conversion relationship between the time domain and the frequency domain of the dielectric response.

[0012] In the above solution, the determining of the relevant parameters of the medium broadband equivalent model according to the FDS data specifically includes:

[0013] Preprocessing the FDS data, and converting the preprocessed FDS data into complex capacitance and dielectric loss angle;

[0014] Determining parameters of the broadband equivalent model of the medium;

[0015] Preset iteration conditions;

[0016] Iterating the parameters of the medium broadband equivalent model based on the FDS data;

[0017] When the iteration condition is met, the relevant parameters of the dielectric broadband equivalent model are obtained, and the relevant parameters of the dielectric broadband equivalent model include: insulation resistance R0, geometric capacitance C0, resistance R of the RC series branch i and capacitor C i , i is a positive integer.

[0018] In the above scheme, before simulating the polarization-depolarization current PDC according to the time-domain dielectric response equivalent circuit, the method further includes: determining the correlation between the polarization-depolarization current PDC and the time-domain dielectric response equivalent circuit:

[0019] According to the polarization current in the time-domain dielectric response, the zero-state response of the time-domain dielectric response equivalent circuit is determined:

[0020]

[0021] Among them, i p represents zero-state response, U0 represents external DC voltage, R0 represents insulation resistance, R k represents the resistance in the RC series branch corresponding to the kth relaxation time, t represents the current time, τ k represents the kth relaxation time, e represents a natural constant, k is a positive integer, and n is an integer greater than or equal to 1;

[0022] According to the depolarization current in the time-domain dielectric response, the zero-input response of the time-domain dielectric response equivalent circuit is determined:

[0023]

[0024] Among them, i d Represents input response, A k It is used to characterize the impact of charging in the previous stage, t represents the current time, τ k represents the kth relaxation time, e represents a natural constant, k is a positive integer, n is an integer greater than or equal to 1, U0 represents an external DC voltage, R k represents the resistance in the RC series branch corresponding to the kth relaxation time, t c Indicates the medium charging time.

[0025] In the above scheme, the conversion of the pre-processed FDS data into complex capacitance and dielectric loss angle specifically includes:

[0026] The complex capacitance is determined according to the relevant parameters of the broadband equivalent model of the dielectric:

[0027]

[0028] The dielectric loss angle is determined based on the imaginary and real parts of the complex capacitance:

[0029]

[0030] Where ω represents the capacitance angular frequency, C′(ω) represents the real part of the complex capacitance, C″(ω) represents the imaginary part of the complex capacitance, tanδ represents the tangent value of the dielectric loss angle, δ represents the dielectric loss angle, C0 represents the geometric capacitance, R0 represents the insulation resistance, C i and R i They respectively represent the resistance and capacitance in the RC series branch corresponding to the i-th relaxation time, and i is a positive integer.

[0031] In the above scheme, the corresponding time-domain dielectric response equivalent circuit is constructed according to the broadband equivalent model of the medium, specifically including:

[0032] According to the relevant parameters of the medium broadband equivalent model, the values ​​of the electronic components of the equivalent circuit are determined, and the electronic components of the equivalent circuit include: the medium to be measured, the excitation source, the internal resistance of the measuring instrument and the equivalent circuit.

[0033] In the above scheme, the analysis of the PDC curve to determine the equivalent conversion relationship between the time domain and the frequency domain of the dielectric response specifically includes:

[0034] Extracting key features from the PDC curve, the key features comprising: polarization current peak, depolarization current decay rate, polarization time constant and depolarization time constant;

[0035] Fitting relevant parameters of the medium broadband equivalent model according to the key features;

[0036] Based on the relevant parameters obtained by fitting, the PDC curve is converted into frequency domain dielectric spectrum parameters;

[0037] Determine a corresponding time domain verification PDC curve according to the frequency domain dielectric spectrum parameters;

[0038] When the error between the PDC curve and the time-domain verification PDC curve satisfies the error condition, an equivalent conversion between the time domain and the frequency domain of the dielectric response is achieved based on the PDC curve.

[0039] In the above scheme, the analysis of the PDC curve to determine the equivalent conversion relationship between the time domain and the frequency domain of the dielectric response also includes:

[0040] Collect measured PDC curves;

[0041] comparing the PDC curve with the measured PDC curve;

[0042] An evaluation result of an equivalent conversion between the time domain and the frequency domain of the dielectric response is obtained.

[0043] The present application also proposes a time-domain and frequency-domain equivalent system of dielectric response, the system comprising: an FDS data acquisition unit, a circuit construction unit, a simulation unit and an analysis unit;

[0044] The FDS data acquisition unit is used to acquire frequency domain dielectric spectrum FDS data of the insulating medium;

[0045] The circuit building unit is used to determine relevant parameters of the dielectric broadband equivalent model according to the frequency domain dielectric spectrum FDS data; and to build a corresponding time domain dielectric response equivalent circuit according to the dielectric broadband equivalent model;

[0046] The simulation unit is used to simulate the polarization depolarization current PDC according to the time domain dielectric response equivalent circuit to obtain a PDC curve;

[0047] The analysis unit is used to analyze the PDC curve to determine the equivalent conversion relationship between the time domain and the frequency domain of the dielectric response.

[0048] The present application also proposes a readable storage medium storing a computer program. When the computer program is executed by a processor, the processor executes the following steps:

[0049] Obtain FDS data of insulating medium;

[0050] Determine relevant parameters of the medium broadband equivalent model according to the FDS data;

[0051] According to the broadband equivalent model of the medium, a corresponding time-domain dielectric response equivalent circuit is constructed;

[0052] Simulating the PDC according to the time-domain dielectric response equivalent circuit to obtain a PDC curve;

[0053] The PDC curve is analyzed to determine the equivalent conversion relationship between the time domain and the frequency domain of the dielectric response.

[0054] The present application also proposes a computer device, including a memory and a processor, wherein the memory stores a computer program, and the computer program is executed by the processor in the following steps:

[0055] Obtain FDS data of insulating medium;

[0056] Determine relevant parameters of the medium broadband equivalent model according to the FDS data;

[0057] According to the broadband equivalent model of the medium, a corresponding time-domain dielectric response equivalent circuit is constructed;

[0058] Simulating the PDC according to the time-domain dielectric response equivalent circuit to obtain a PDC curve;

[0059] The PDC curve is analyzed to determine the equivalent conversion relationship between the time domain and the frequency domain of the dielectric response.

[0060] The embodiment of the present invention has the following beneficial effects: first obtain the FDS data of the insulating medium; determine the relevant parameters of the broadband equivalent model of the medium according to the DS data; build the corresponding time-domain dielectric response equivalent circuit according to the broadband equivalent model of the medium; simulate the PDC according to the time-domain dielectric response equivalent circuit to obtain the PDC curve; analyze the PDC curve to determine the time-domain and frequency-domain equivalent conversion relationship of the dielectric response. This method obtains the dielectric property data of the insulating medium at different frequencies through FDS testing, and then uses these data to determine the relevant parameters of the broadband equivalent model of the medium, constructs a model that can simulate the behavior of the medium, and then builds a time-domain dielectric response equivalent circuit based on the model, and obtains the polarization and depolarization current PDC curve through circuit simulation. Finally, by analyzing the PDC curve obtained by simulation, the equivalent conversion relationship between the time domain and the frequency domain is established, thereby achieving a comprehensive understanding and evaluation of the characteristics of the insulating medium. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0062] in:

[0063] Figure 1 It is a schematic diagram of the flow chart of the time-domain and frequency-domain equivalent method of dielectric response in one embodiment;

[0064] Figure 2 A schematic diagram of an equivalent circuit of an extended Debye model in one embodiment;

[0065] Figure 3 A schematic diagram of a PDC simulation circuit structure in one embodiment;

[0066] FIG. 4( a ) is a schematic diagram of simulated and measured polarization current curves in one embodiment.

[0067] FIG. 4( b ) is a schematic diagram of simulated and measured depolarization current curves in one embodiment. DETAILED DESCRIPTION

[0068] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0069] In the prior art, polarization depolarization current method (PDC) and frequency domain dielectric spectroscopy (FDS) are both means of testing the dielectric properties of dielectrics, but the test circuits of the two are different, and the test voltages are also different. Specifically, the polarization depolarization current method test circuit contains the internal resistance of the instrument in addition to the test object, and the voltage applied in the circuit is a step voltage. Since the insulating medium exhibits capacitive electrical characteristics in most frequency bands (about mHz and above), the initial charging current flowing through the test circuit is large; the frequency domain dielectric spectroscopy method test circuit only contains the test object, and the applied voltage is a sinusoidal voltage. Since the tested voltage and current are both the voltage and current of the medium port, the frequency domain dielectric spectrum test results can fully reflect the dielectric properties of the medium.

[0070] Although the PDC and FDS methods have been widely used in the study of dielectric properties of insulating materials, existing research schemes in practical applications tend to simply list the test parameters of each method, lacking in-depth thinking and equivalence analysis of the test data, which limits the comprehensive understanding and analysis of the properties of insulating materials.

[0071] In order to overcome the shortcomings of existing research methods, this application proposes a time domain and frequency domain equivalent method for dielectric response, provides theoretical support for the rational use of various dielectric response test methods, and establishes an equivalent conversion relationship between time domain and frequency domain dielectric responses, so as to more comprehensively analyze the characteristics of insulating materials. This method can help researchers to have a deeper understanding of the dielectric properties of insulating materials and provide theoretical guidance for the research and development and application of insulating materials.

[0072] To facilitate understanding, the relevant terms involved in this application are first introduced below.

[0073] Frequency domain dielectric spectrum FDS data, FDS data refers to the data set of dielectric constant and dielectric loss of the medium measured at a series of different frequencies. These data reflect the characteristics of the material's permittivity and energy loss changing with frequency under the action of an electric field. Through these data, the dielectric behavior of the medium can be analyzed, including the storage and loss mechanism of charge, and the dielectric relaxation phenomenon of the material;

[0074] Polarization and depolarization current (PDC), PDC refers to the current generated in dielectric materials due to applied voltage. It includes two main processes: polarization current and depolarization current. Through this current information, the dielectric properties, loss conditions, microstructure and defects inside the dielectric can be obtained.

[0075] Dielectric loss angle, dielectric loss angle (Dielectric Loss Angle) is a physical quantity that describes the energy loss of a dielectric in an alternating electric field. When an AC voltage is applied to a dielectric, due to the non-ideal characteristics of the dielectric, part of the electrical energy will be converted into heat energy. This process is called dielectric loss, and the dielectric loss angle is used to quantify this energy loss.

[0076] In order to thoroughly understand the present invention, a detailed structure will be presented in the following description to illustrate the technical solution proposed by the present invention; optional embodiments of the present invention are described in detail as follows, but in addition to these detailed descriptions, the present invention may also have other implementation methods.

[0077] like Figure 1 As shown, in one embodiment, a time-domain and frequency-domain equivalent method of dielectric response is provided, which can be applied to both a terminal and a server. The time-domain and frequency-domain equivalent method of dielectric response includes steps S101 to S105, which are described in detail as follows:

[0078] S101, obtaining frequency domain dielectric spectrum FDS data of an insulating medium.

[0079] Specifically, this step requires measuring the dielectric properties of the insulating medium at different frequencies, usually including the dielectric constant ε' and dielectric loss ε", these data are usually given as a function of frequency, constituting the frequency domain dielectric spectrum FDS data.

[0080] S102, determining relevant parameters of a dielectric broadband equivalent model according to frequency domain dielectric spectrum FDS data.

[0081] By analyzing the FDS data, the parameters of the dielectric equivalent model, such as insulation resistance, capacitance, etc., are determined to provide a basis for building an equivalent circuit. The frequency domain data needs to be fitted through an appropriate equivalent circuit model (such as the Cole-Cole model, the Davidson-Cole model, etc.). These models describe the dielectric behavior of the insulating medium through specific parameters (such as distribution parameters, relaxation time, etc.). Through the fitting process, these model parameters can be extracted, and these parameters will be used to construct the time domain equivalent circuit.

[0082] In some embodiments, the relevant parameters of the medium broadband equivalent model are determined according to the frequency domain dielectric spectrum FDS data, specifically including:

[0083] Preprocess the frequency domain dielectric spectrum FDS data and convert the preprocessed FDS data into complex capacitance and dielectric loss angle;

[0084] Determine the parameters of the broadband equivalent model of the medium;

[0085] Preset iteration conditions;

[0086] Based on FDS data, the parameters of the medium broadband equivalent model are iterated;

[0087] When the iteration conditions are met, the relevant parameters of the dielectric broadband equivalent model are obtained. The relevant parameters of the dielectric broadband equivalent model include: insulation resistance R0, geometric capacitance C0, resistance R of the RC series branch i and capacitor C i , i is a positive integer.

[0088] Preferably, before starting preprocessing, it is necessary to ensure that the equipment in the data acquisition process is calibrated correctly and the acquisition environment is stable to reduce the error of the initial data. If there are long-term trends or drifts in the data, these components are removed by linear or nonlinear fitting methods, and then a digital filter (such as a low-pass, high-pass, band-pass or band-stop filter) is applied to remove high-frequency noise or low-frequency drift in the data. The appropriate filter type and cutoff frequency are set to retain useful signal components while removing unnecessary noise.

[0089] The above preprocessing steps also include data smoothing (such as moving average, exponential smoothing or median filtering to reduce random noise), detrending, normalization, etc., to preprocess the acquired frequency domain dielectric spectrum FDS data in order to eliminate noise and outliers in the measurement process and ensure the accuracy and reliability of the data. The preprocessed FDS data is converted into complex capacitance and dielectric loss angle. This conversion is achieved by mathematically processing the relationship between dielectric constant and frequency, thereby providing direct input parameters for the establishment of an equivalent model.

[0090] Determine the parameters of the broadband equivalent model of the medium, which usually involves selecting an appropriate model structure, such as the Debye model or the Cole-Cole model, and determining the number and type of parameters required in the model. The complexity of the model can be determined based on the characteristics of the medium and the intended application scenario.

[0091] The preset iteration conditions include the maximum number of iterations, the minimum threshold of parameter changes, the convergence criterion, etc. These conditions are set to ensure that the iteration process can be carried out effectively and stop after reaching a certain accuracy to avoid unnecessary waste of computing resources.

[0092] Based on the FDS data, the parameters of the dielectric broadband equivalent model are iterated. This step usually involves using optimization algorithms, such as least squares, genetic algorithms, or other numerical methods, to adjust the model parameters so that the complex capacitance and dielectric loss angle predicted by the model are as close as possible to the actual measured data.

[0093] When the preset iteration conditions are met, the iteration process is stopped and the relevant parameters of the medium broadband equivalent model are obtained. These parameters include the insulation resistance R0, which represents the insulation performance of the medium; the geometric capacitance C0, which reflects the capacitance characteristics of the medium; and the resistance R of the RC series branch. i and capacitance Ci, i is a positive integer. These parameters describe the polarization behavior of the medium at different frequencies. Through these parameters, an accurate equivalent circuit model can be constructed for further analysis and simulation.

[0094] Preferably, based on the broadband equivalent model of the dielectric and the mathematical expression contained therein, an analysis method for the relationship between the macroscopic dielectric parameters and the microscopic dielectric behavior of the insulating medium can be established. At the same time, according to the circuit topology relationship and circuit constraints in the equivalent circuit model, the voltage and current conditions of the insulating medium can be analyzed in the time domain and frequency domain, and further, the conversion relationship between the time domain and frequency domain of the dielectric response can be studied.

[0095] S103. Construct a corresponding time-domain dielectric response equivalent circuit based on the broadband equivalent model of the medium.

[0096] By analyzing FDS data, the parameters of the dielectric equivalent model, such as insulation resistance, capacitance, etc., are determined to provide a basis for building an equivalent circuit. The frequency domain characteristics of the medium are converted into a time domain equivalent circuit to facilitate time domain simulation analysis.

[0097] In some embodiments, a corresponding time-domain dielectric response equivalent circuit is constructed according to the broadband equivalent model of the medium, specifically including:

[0098] The time domain dielectric response equivalent circuit includes: the medium to be measured, the excitation source, the internal resistance of the measuring instrument and the equivalent circuit;

[0099] The values ​​of the electronic components of the equivalent circuit are determined according to the relevant parameters of the dielectric broadband equivalent model.

[0100] S104, simulating the polarization depolarization current PDC according to the time domain dielectric response equivalent circuit to obtain a PDC curve.

[0101] By simulating the polarization and depolarization current curve of the medium, the polarization characteristics of the medium, such as polarization intensity and polarization time constant, can be analyzed.

[0102] Specifically, circuit simulation software or tools are used to simulate the constructed time domain equivalent circuit. By applying an appropriate voltage or current excitation, the time-varying curve of the polarization depolarization current (PDC) can be calculated. The PDC curve is a direct manifestation of the dielectric response in the time domain, which reflects the redistribution and relaxation process of the charge inside the medium.

[0103] In some embodiments, using Figure 2 The extended Debye model equivalent circuit shown is used as an equivalent circuit. The traditional Debye model uses a single RC series branch to equivalently represent the dielectric relaxation process. However, the insulating medium under the action of the electric field has a variety of dielectric response processes with different equivalent relaxation times. Therefore, in order to more accurately describe the conductivity and polarization characteristics of the medium, the traditional Debye model is equivalent to an improved combined circuit model by adding a series of resistor-capacitor series polarization branches, which is the extended Debye model. Among them, C0 represents the geometric capacitance of the insulating medium, R0 represents the insulation resistance, which characterizes the conductivity characteristics of the dielectric, and multiple resistor and capacitor series branches represent different relaxation times τ. i The dielectric polarization process under i =R i C i , i is a positive integer.

[0104] In some embodiments, before simulating the polarization depolarization current PDC according to the time domain dielectric response equivalent circuit, the method further includes: determining a correlation relationship between the polarization depolarization current PDC and the time domain dielectric response equivalent circuit:

[0105] Determine the zero-state response of the time-domain dielectric response equivalent circuit based on the polarization current in the time-domain dielectric response:

[0106]

[0107] Among them, i p represents zero-state response, U0 represents external DC voltage, R0 represents insulation resistance, R k represents the resistance in the RC series branch corresponding to the kth relaxation time, t represents the current time, τ k represents the kth relaxation time, e represents a natural constant, k is a positive integer, and n is an integer greater than or equal to 1.

[0108] Determine the zero input response of the time domain dielectric response equivalent circuit based on the depolarization current in the time domain dielectric response:

[0109]

[0110] Among them, i d Represents input response, A k It is used to characterize the impact of charging in the previous stage, t represents the current time, τ k represents the kth relaxation time, e represents a natural constant, k is a positive integer, n is an integer greater than or equal to 1, U0 represents an external DC voltage, R k represents the resistance in the RC series branch corresponding to the kth relaxation time, t c Indicates the medium charging time.

[0111] Among them, the polarization current in the time domain dielectric response is reflected as the zero-state response of the equivalent circuit, and the depolarization current is the zero-input response of the extended Debye circuit of the equivalent circuit, which is equal to the sum of the relaxation currents of each polarization branch.

[0112] In some embodiments, the pre-processed FDS data is converted to represent complex capacitance and dielectric loss angle, specifically including:

[0113] Determine the complex capacitance based on the relevant parameters of the broadband equivalent model of the dielectric:

[0114]

[0115]

[0116] Determine the dielectric loss angle based on the imaginary and real parts of the complex capacitance:

[0117]

[0118] Where ω represents the capacitance angular frequency, C′(ω) represents the real part of the complex capacitance, C″(ω) represents the imaginary part of the complex capacitance, tanδ represents the tangent value of the dielectric loss angle, δ represents the dielectric loss angle, C0 is the geometric capacitance, R0 represents the insulation resistance, C i and R i They respectively represent the resistance and capacitance in the RC series branch corresponding to the i-th relaxation time, and i is a positive integer.

[0119] Specifically, the commonly used parameters of frequency domain dielectric spectroscopy are complex capacitance and dielectric loss tangent. The dielectric loss tangent is defined as the ratio of the imaginary part of the complex capacitance to the real part.

[0120] It can be seen that formula (1)-formula (6) give the relationship between the dielectric spectrum parameters and the equivalent circuit element values ​​in the equivalent form of the extended Debye model. The inverse solution of the model parameters can be achieved through the above expressions and dielectric response data;

[0121] Formula (1)-Formula (3) establish the relationship between the time-domain polarization and depolarization current and the model branch. The model parameters can be identified by the distribution fitting method. The high-frequency information loss of the measured PDC curve will also be reflected in the model parameters, and the effects of factors such as circuit internal resistance and excitation voltage waveform are not considered.

[0122] Formula (4)-Formula (6) respectively establish the correlation between the frequency domain dielectric parameters complex capacitance and dielectric loss tangent and the model branch parameters.

[0123] Preferably, based on the frequency domain spectrum FDS, the model parameters identified by the GA-LM fusion algorithm have good broadband accuracy, and a set of suitable R n , C n (n is a positive integer) value satisfies the measured frequency domain dielectric spectrum function formula (4)-formula (6), and can achieve the overall equivalence of the dielectric behavior of the medium.

[0124] Among them, the number of polarization branches of the extended Debye model can generally be taken as 6 to 10. When the number of branches is less than 5, the goodness of fit will significantly increase with the increase of the number of branches. When the number of branches is higher than 5, the goodness of fit approaches saturation. Therefore, according to the frequency range, considering the goodness of fit and calculation difficulty, the number of branches is set to 6, which can simulate 6 different relaxation time constants, which helps to more finely describe the various relaxation processes existing in the material. At the same time, it can make the model better fit the experimentally measured data of the dielectric constant and dielectric loss tangent varying with frequency, thereby reducing the fitting error.

[0125] S105, analyzing the PDC curve to determine the equivalent conversion relationship between the time domain and the frequency domain of the dielectric response.

[0126] By analyzing the characteristics of the PDC curve (such as peak time, relaxation time, etc.), the equivalent conversion relationship between the time domain dielectric response and the frequency domain dielectric performance can be derived, and the mutual conversion of the time domain and frequency domain dielectric responses can be realized, which is convenient for analysis and research in different fields. This equivalent conversion relationship between the time domain and frequency domain of the dielectric response includes mathematical expressions, charts or empirical formulas, which are used to convert dielectric performance data between the time domain and the frequency domain.

[0127] In some embodiments, the PDC curve is analyzed to determine the equivalent conversion relationship between the time domain and the frequency domain of the dielectric response, specifically including:

[0128] Extract key features from PDC curves: Key features include: polarization current peak, depolarization current decay rate, polarization time constant and depolarization time constant;

[0129] Fitting the relevant parameters of the medium broadband equivalent model according to the key features;

[0130] Based on the relevant parameters obtained by fitting, the PDC curve is converted into frequency domain dielectric spectrum parameters;

[0131] Determine the corresponding time domain verification PDC curve based on the frequency domain dielectric spectrum parameters;

[0132] When the error between the PDC curve and the time domain verification PDC curve meets the error condition, the equivalent conversion between the time domain and the frequency domain of the dielectric response is realized based on the PDC curve.

[0133] Specifically, the peak value of polarization current: This is the maximum value reached by the current during the polarization process, which reflects the maximum polarization degree of the medium under the action of the electric field;

[0134] Depolarization current decay rate: This is the rate at which the current decreases during the depolarization process, which is related to the depolarization behavior and relaxation time of the medium;

[0135] Polarization time constant: This is the time required for the polarization current to reach its peak value, which represents the speed at which the medium responds to the external electric field;

[0136] Depolarization time constant: This is the time required for the depolarization current to decay to a certain ratio, which describes the speed of medium depolarization.

[0137] Preferably, the parameters of the equivalent model can be fitted by a nonlinear least squares method so that the model can better simulate the PDC behavior of the actual medium.

[0138] In some embodiments, analyzing the PDC curve to determine the equivalent conversion relationship between the time domain and the frequency domain of the dielectric response further includes:

[0139] Collect measured PDC curves;

[0140] Compare the PDC curve with the measured PDC curve;

[0141] Obtain evaluation results for the equivalent conversion of the dielectric response between the time domain and the frequency domain.

[0142] Preferably, the measured curve is compared with the curve reconstructed by formula (4)-formula (6), and the standard root mean square error (NRMSE) is used to obtain the quantitative fitting degree:

[0143]

[0144] Among them, NRMSE represents the quantitative fitting degree, xref(n) is the reference array, that is, the measured data, x(n) is the calculation array, that is, the data obtained by parameter identification, i is a positive integer, and m is an integer greater than or equal to 1.

[0145] The closer the NRMSE is to 1, the better the fitting effect is, and the more accurate the evaluation result of the equivalent conversion between the time domain and frequency domain of the dielectric response is.

[0146] Preferably, a DC high voltage source and a current measuring device can be used to apply a DC voltage to the insulating medium, and record the current flowing through the medium during the depolarization process, and collect the measured PDC curve. The measured PDC curve usually reflects the polarization behavior of the medium at different time points, including the rise and decay process of the polarization current.

[0147] Among them, comparing the simulated PDC curve with the measured PDC curve is to verify the accuracy of the simulation model and ensure that the model can reasonably reproduce the polarization characteristics of the actual medium. The comparison process may include visual comparison, error analysis, correlation evaluation, etc. Through comparison, the difference between the model prediction and the actual measurement can be identified, and the model can be adjusted and optimized.

[0148] Finally, obtaining the evaluation results of the equivalent conversion between the time domain and the frequency domain of the dielectric response is a quantitative analysis of the comparison results to evaluate the effectiveness of the equivalent conversion relationship. The evaluation results include the following aspects:

[0149] Error analysis: Calculate the statistical error (such as mean square error, maximum error, etc.) between the simulated PDC curve and the measured PDC curve to quantify the prediction accuracy of the model.

[0150] Correlation evaluation: Use statistical indicators such as correlation coefficient to evaluate the correlation between the simulation curve and the measured curve to determine the reliability of the model.

[0151] Parameter sensitivity analysis: Analyze the effect of model parameters on the shape of the PDC curve to determine which parameters have the greatest impact on the equivalent conversion relationship.

[0152] Conversion relationship verification: By converting the time domain data into frequency domain data and comparing it with the original FDS data, the correctness of the equivalent conversion relationship between the time domain and the frequency domain is verified.

[0153] Through these evaluation results, the equivalent conversion relationship between the time domain and frequency domain of the dielectric response can be accurately obtained, and this relationship can be used in practical applications to more accurately analyze and predict the performance of the insulating medium.

[0154] In some embodiments, in order to compare the similarities and differences between the dielectric responses in the time domain and frequency domain, after obtaining the extended Debye model and parameters based on FDS identification, a PDC simulation circuit is built, such as Figure 3 As shown in the figure, Rm is the internal resistance of the instrument. The specific parameters of the model are obtained according to the FDS identification of different samples. By substituting them into the simulation circuit, the conversion from FDS to its corresponding PDC spectrum can be realized.

[0155] Specifically, the tests were carried out at 30°C, 50°C, and 70°C, and the comparison between the simulated and measured polarization current curves and the simulated and measured depolarization current curves was shown in Figure 2. Figure 4(a) , 4(b) As shown, the goodness of fit between the measured reconstructed polarization and depolarization current and the measured polarization and depolarization current is more than 0.95, which proves that the method of converting FDS to PDC in the present invention is feasible and effective.

[0156] Table 1 is based on the above Figure 4(a) , 4(b) The shown fit data are based on different temperature conditions.

[0157] Table 1 Goodness of fit between measured and simulated polarization and depolarization currents

[0158]

[0159] According to the above simulation results, it can be seen that the PDC curve calculated by FDS conversion is in good agreement with the measured results in the low frequency band, which verifies the consistency between the time domain dielectric response and the frequency domain dielectric response, and can provide a systematic analysis strategy and reference scheme for dielectric response related research.

[0160] In summary, the present invention obtains an accurately fitted broadband equivalent model of the dielectric through FDS frequency domain data, builds a time domain dielectric response test equivalent simulation circuit, analyzes the similarities and differences between the simulated time domain data and the actual time domain data, and determines the time domain and frequency domain equivalence characteristics. This method has four major advantages: reasonable model equivalence, accurate parameter selection, good broadband fitting, and easy implementation of the method. Through the established high-precision broadband equivalent model of the dielectric, the FDS data of the insulating medium is used to reconstruct the PDC curve, and the equivalence of the time domain and frequency domain methods in characterizing the characteristics of the insulating medium is fully explored.

[0161] The present application also proposes a time-domain and frequency-domain equivalent system of dielectric response, the system comprising: an FDS data acquisition unit, a circuit building unit, a simulation unit and an analysis unit;

[0162] An FDS data acquisition unit, used for acquiring frequency domain dielectric spectrum FDS data of the insulating medium;

[0163] A circuit building unit is used to determine relevant parameters of a dielectric broadband equivalent model according to the frequency domain dielectric spectrum FDS data; and to build a corresponding time domain dielectric response equivalent circuit according to the dielectric broadband equivalent model;

[0164] A simulation unit, used for simulating the polarization and depolarization current PDC according to a time domain dielectric response equivalent circuit to obtain a PDC curve;

[0165] The analysis unit is used to analyze the PDC curve and determine the equivalent conversion relationship between the time domain and the frequency domain of the dielectric response.

[0166] The present application also proposes a readable storage medium storing a computer program. When the computer program is executed by a processor, the processor executes the following steps:

[0167] Obtain frequency domain dielectric spectrum FDS data of insulating media;

[0168] Determine the relevant parameters of the medium broadband equivalent model based on the frequency domain dielectric spectrum FDS data;

[0169] Build the corresponding time-domain dielectric response equivalent circuit according to the broadband equivalent model of the medium;

[0170] The polarization and depolarization current PDC is simulated according to the time domain dielectric response equivalent circuit to obtain the PDC curve;

[0171] The PDC curve is analyzed to determine the equivalent conversion relationship between the time domain and frequency domain of the dielectric response.

[0172] The present application also proposes a computer device, including a memory and a processor, wherein the memory stores a computer program, and the computer program is executed by the processor in the following steps:

[0173] Obtain frequency domain dielectric spectrum FDS data of insulating media;

[0174] Determine the relevant parameters of the medium broadband equivalent model based on the frequency domain dielectric spectrum FDS data;

[0175] Build the corresponding time-domain dielectric response equivalent circuit according to the broadband equivalent model of the medium;

[0176] The polarization and depolarization current PDC is simulated according to the time domain dielectric response equivalent circuit to obtain the PDC curve;

[0177] The PDC curve is analyzed to determine the equivalent conversion relationship between the time domain and frequency domain of the dielectric response.

[0178] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the program can be stored in a non-volatile computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0179] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0180] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A time-domain and frequency-domain equivalent method for dielectric response, characterized in that: The method comprises: Obtain frequency domain dielectric spectrum FDS data of insulating media; Determine relevant parameters of the medium broadband equivalent model according to the FDS data; According to the broadband equivalent model of the medium, a corresponding time-domain dielectric response equivalent circuit is constructed; Simulating the polarization depolarization current PDC according to the time domain dielectric response equivalent circuit to obtain a PDC curve; The PDC curve is analyzed to determine the equivalent conversion relationship between the time domain and the frequency domain of the dielectric response.

2. The time-domain and frequency-domain equivalent method of dielectric response according to claim 1, characterized in that: Determining the relevant parameters of the medium broadband equivalent model according to the FDS data specifically includes: Preprocessing the FDS data, and converting the preprocessed FDS data into complex capacitance and dielectric loss angle; Determining parameters of the broadband equivalent model of the medium; Preset iteration conditions; Iterating the parameters of the medium broadband equivalent model based on the FDS data; When the iteration condition is met, the relevant parameters of the dielectric broadband equivalent model are obtained, and the relevant parameters of the dielectric broadband equivalent model include: insulation resistance R0, geometric capacitance C0, resistance R of the RC series branch i and capacitor C i , i is a positive integer.

3. The time-domain and frequency-domain equivalent method of dielectric response according to claim 2, characterized in that: Before simulating the polarization depolarization current PDC according to the time domain dielectric response equivalent circuit, the method further includes: Determine the correlation between the PDC and the time-domain dielectric response equivalent circuit: According to the polarization current in the time-domain dielectric response, the zero-state response of the time-domain dielectric response equivalent circuit is determined: Among them, i p represents zero-state response, U0 represents external DC voltage, R0 represents insulation resistance, R k represents the resistance in the RC series branch corresponding to the kth relaxation time, t represents the current time, τ k represents the kth relaxation time, e represents a natural constant, k is a positive integer, and n is an integer greater than or equal to 1; According to the depolarization current in the time-domain dielectric response, the zero-input response of the time-domain dielectric response equivalent circuit is determined: Among them, i d Indicates input response, A k It is used to characterize the impact of charging in the previous stage, t represents the current time, τ k represents the kth relaxation time, e represents a natural constant, k is a positive integer, n is an integer greater than or equal to 1, U0 represents an external DC voltage, R k represents the resistance in the RC series branch corresponding to the kth relaxation time, t c Indicates the medium charging time.

4. The time-domain and frequency-domain equivalent method of dielectric response according to claim 2, characterized in that: The converting of the pre-processed FDS data into complex capacitance and dielectric loss angle specifically includes: The complex capacitance is determined according to the relevant parameters of the broadband equivalent model of the dielectric: The dielectric loss angle is determined based on the imaginary and real parts of the complex capacitance: Where ω represents the capacitance angular frequency, C′(ω) represents the real part of the complex capacitance, C″(ω) represents the imaginary part of the complex capacitance, tanδ represents the tangent value of the dielectric loss angle, δ represents the dielectric loss angle, C0 is the geometric capacitance, R0 represents the insulation resistance, C i and R i They respectively represent the resistance and capacitance in the RC series branch corresponding to the i-th relaxation time, and i is a positive integer.

5. The time-domain and frequency-domain equivalent method of dielectric response according to claim 1, characterized in that: The step of building a corresponding time-domain dielectric response equivalent circuit according to the broadband equivalent model of the medium specifically includes: According to the relevant parameters of the medium broadband equivalent model, the values ​​of the electronic components of the equivalent circuit are determined, and the electronic components of the equivalent circuit include: the medium to be measured, the excitation source, the internal resistance of the measuring instrument and the equivalent circuit.

6. The time-domain and frequency-domain equivalent method of dielectric response according to any one of claims 1 to 5, characterized in that: The analyzing the PDC curve to determine the equivalent conversion relationship between the time domain and the frequency domain of the dielectric response specifically includes: Extracting key features from the PDC curve, the key features comprising: polarization current peak, depolarization current decay rate, polarization time constant and depolarization time constant; Fitting relevant parameters of the medium broadband equivalent model according to the key features; Based on the relevant parameters obtained by fitting, the PDC curve is converted into frequency domain dielectric spectrum parameters; Determine a corresponding time domain verification PDC curve according to the frequency domain dielectric spectrum parameters; When the error between the PDC curve and the time-domain verification PDC curve satisfies the error condition, an equivalent conversion between the time domain and the frequency domain of the dielectric response is achieved based on the PDC curve.

7. The time-domain and frequency-domain equivalent method of dielectric response according to any one of claims 1 to 5, characterized in that: The step of analyzing the PDC curve to determine the equivalent conversion relationship between the time domain and the frequency domain of the dielectric response further includes: Collect measured PDC curves; comparing the PDC curve with the measured PDC curve; An evaluation result of an equivalent conversion between the time domain and the frequency domain of the dielectric response is obtained.

8. A time-domain and frequency-domain equivalent system of dielectric response, characterized in that: The system comprises: an FDS data acquisition unit, a circuit construction unit, a simulation unit and an analysis unit; The FDS data acquisition unit is used to acquire frequency domain dielectric spectrum FDS data of the insulating medium; The circuit building unit is used to determine relevant parameters of the dielectric broadband equivalent model according to the frequency domain dielectric spectrum FDS data; and to build a corresponding time domain dielectric response equivalent circuit according to the dielectric broadband equivalent model; The simulation unit is used to simulate the polarization depolarization current PDC according to the time domain dielectric response equivalent circuit to obtain a PDC curve; The analysis unit is used to analyze the PDC curve to determine the equivalent conversion relationship between the time domain and the frequency domain of the dielectric response.

9. A readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor executes the steps of the method for time-domain and frequency-domain equivalent of dielectric response according to any one of claims 1 to 7.

10. A device for time-domain and frequency-domain equivalent of dielectric response, comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the time-domain and frequency-domain equivalent method of dielectric response as claimed in any one of claims 1 to 7.

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