Construction method and construction system of insulation paper moisture-frequency domain dielectric spectrum database

Abstract

The invention belongs to the related technical field of dielectric properties of electrical insulating materials, and discloses a construction method and a construction system for a moisture-frequency domain dielectric spectrum database of insulating paper, and the construction method comprises the steps: constructing a moisture-frequency three-dimensional dielectric model; wherein the complex dielectric response of the complex dielectric response calculation constraint characterization insulation paper at least comprises complex dielectric responses of an optical frequency dielectric constant, a jump conductance process, a low-frequency relaxation polarization process and a high-frequency relaxation polarization process; calculating an index value of a quadratic unary equation for constraining and representing jump conductivity including water content by jump conductivity calculation, and calculating an index value of a quadratic unary equation for constraining and representing relaxation time of a low-frequency relaxation polarization process including water content by low-frequency relaxation time calculation; the target function minimizes the deviation between the measured value and the model calculation value; and solving the model to obtain an insulation paper moisture-frequency domain dielectric spectrum database. Through the method, the accuracy and reliability of the dielectric spectrum database can still be ensured under the condition of limited experimental data.

Description

Technical Field

[0001] The present invention belongs to the technical field related to the dielectric properties of electrical insulating materials, and more specifically, relates to a method for constructing an insulating paper moisture-frequency domain dielectric spectrum database and a construction system thereof. Background Art

[0002] Insulating paper is an important insulating material in electrical equipment such as transformers. Its performance is closely related to its moisture content, and changes in moisture directly affect the dielectric properties of insulating paper. Therefore, it is crucial to accurately obtain the dielectric properties of insulating paper at different moisture contents. Frequency domain dielectric spectroscopy, as a non-destructive testing tool, is widely used in the study of dielectric properties of insulating materials because it can provide rich complex dielectric response information. By measuring the frequency domain dielectric spectrum of insulating paper at different moisture contents, the impact of moisture changes on its dielectric properties can be obtained. The insulation paper moisture-frequency domain dielectric spectrum database can not only provide large-scale, high-quality data support for model establishment, but also provide a reliable basis for insulating paper status assessment.

[0003] Traditional methods typically use interpolation to generate multiple spectral data points at different moisture contents to create a spectral database. However, when the amount of experimental data is insufficient, the accuracy of the interpolation cannot be guaranteed. Furthermore, the interpolated database lacks sufficient physical basis, which can easily lead to errors when the moisture content varies significantly, thus affecting the accuracy and reliability of the dielectric spectrum database. Summary of the Invention

[0004] In response to the above-mentioned defects or improvement needs of the prior art, the present invention provides a method and system for constructing a moisture-frequency domain dielectric spectrum database for insulating paper, the purpose of which is to ensure the accuracy and reliability of the dielectric spectrum database even when experimental data is limited.

[0005] To achieve the above objectives, according to a first aspect of the present invention, a method for constructing an insulating paper moisture-frequency domain dielectric spectrum database is provided, which comprises:

[0006] Constructing a moisture-frequency three-dimensional dielectric model based on sample parameters of different insulating paper samples, wherein the sample parameters include the moisture content of the sample, the angular frequency of the applied electric field when measuring the complex dielectric response, and the measured complex dielectric response of the sample;

[0007] Solving the model, obtaining the trend of the complex dielectric response of the insulating paper as a function of moisture and angular frequency, and forming a moisture-frequency domain dielectric spectrum database of the insulating paper;

[0008] The model includes constraints and objective functions, wherein the constraints include complex dielectric response calculation constraints, jump conductivity calculation constraints, and relaxation time calculation constraints for low-frequency relaxation polarization processes; the complex dielectric response calculation constraints characterize the complex dielectric response of the insulating paper, including at least the optical frequency dielectric constant, the complex dielectric response of the jump conductivity process, the complex dielectric response of the low-frequency relaxation polarization process, and the complex dielectric response of the high-frequency relaxation polarization process; the jump conductivity calculation constraints characterize the jump conductivity including the exponential value of a quadratic equation of water content, and the low-frequency relaxation time calculation constraints characterize the relaxation time of the low-frequency relaxation polarization process including the exponential value of a quadratic equation of water content; and the objective function is to minimize the deviation between the measured complex dielectric response and the complex dielectric response calculated by the model.

[0009] Optionally, in the complex dielectric response calculation constraint:

[0010] The complex dielectric response of the jump conductance process is expressed as:

[0011]

[0012] Where X is the water content, ω is the angular frequency, ε * hop (ω,X) is the complex dielectric response of the insulating paper with a moisture content of X during the jump conductance process at an angular frequency of ω, σ hop (X) is the jump conductivity of the insulating paper with a moisture content of X, ε0 is the vacuum dielectric constant, and s is the shape parameter of the jump conductivity process;

[0013] The complex dielectric response of the low-frequency relaxation polarization process is expressed as:

[0014]

[0015] Where, ε * p1 (ω,X) is the complex dielectric response of the low-frequency relaxation polarization process of the insulating paper with a moisture content of X at an angular frequency of ω, Δε1 is the low-frequency relaxation polarization intensity, τ1(X) is the relaxation time of the low-frequency relaxation polarization process of the insulating paper with a moisture content of X, and α1 and β1 are the shape parameters of the low-frequency relaxation polarization process;

[0016] The complex dielectric response of the high-frequency relaxation polarization process is expressed as:

[0017]

[0018] Where, ε * p2(ω) is the complex dielectric response of the insulating paper in the high-frequency relaxation polarization process at the angular frequency ω, Δε2 is the high-frequency relaxation polarization intensity, τ2 is the relaxation time of the high-frequency relaxation polarization process, and α2 and β2 are the shape parameters of the high-frequency relaxation polarization process.

[0019] Optionally, in the jump conductivity calculation constraint, the jump conductivity expression is:

[0020] σ hop (X) = exp(a1·X 2 +b1·X+c1);

[0021] Where X is the water content, σ hop (X) is the jump conductivity of the insulating paper with a moisture content of X, and a1, b1, and c1 are the undetermined coefficients of the corresponding quadratic equation.

[0022] Optionally, in the low-frequency relaxation time calculation constraint, the expression for the relaxation time of the low-frequency relaxation polarization process is:

[0023] τ1(X)=exp(a2·X 2 +b2·X+c2);

[0024] Where X is the moisture content, τ1(X) is the relaxation time of the low-frequency relaxation polarization process of the insulating paper with a moisture content of X, and a2, b2, and c2 are the unknown coefficients of the corresponding quadratic equation.

[0025] Optionally, the objective function is expressed as:

[0026]

[0027] Where n is the number of frequency points measured, X is the water content, ω is the angular frequency, ε' paper (ω,X) and ε” paper (ω, X) are the real and imaginary parts of the complex dielectric response of the insulating paper with a moisture content of X at an angular frequency ω output by the model, ε' mea (ω,X) and ε” mea (ω,X) are the real and imaginary parts of the measured complex dielectric response of the insulating paper with a moisture content of X at an angular frequency ω.

[0028] Optionally, a simulated annealing algorithm is used to solve the model.

[0029] Optionally, before building the model, sample parameters of different insulating paper samples are first obtained, and the acquisition process includes:

[0030] Preparation of insulation paper samples with different moisture contents;

[0031] The complex dielectric responses of insulating paper samples with different moisture contents were measured at different angular frequencies.

[0032] According to a second aspect of the present invention, a system for constructing an insulating paper moisture-frequency domain dielectric spectrum database is provided, comprising:

[0033] A parameter acquisition unit is used to obtain sample parameters of different insulating paper samples, the sample parameters including the moisture content of the sample, the angular frequency of the applied electric field when measuring the complex dielectric response, and the measured complex dielectric response of the sample;

[0034] A modeling unit is used to construct a moisture-frequency three-dimensional dielectric model based on sample parameters of different insulating paper samples, the model including constraints and objective functions, the constraints including complex dielectric response calculation constraints, jump conductivity calculation constraints, and low-frequency relaxation time calculation constraints of low-frequency relaxation polarization process; the complex dielectric response calculation constraints characterize the complex dielectric response of the insulating paper, including at least the optical frequency dielectric constant, the complex dielectric response of the jump conductivity process, the complex dielectric response of the low-frequency relaxation polarization process, and the complex dielectric response of the high-frequency relaxation polarization process; the jump conductivity calculation constraints characterize the jump conductivity including the exponential value of the quadratic equation of moisture content, and the low-frequency relaxation time calculation constraints characterize the relaxation time of the low-frequency relaxation polarization process including the exponential value of the quadratic equation of moisture content; the objective function is to minimize the deviation between the measured complex dielectric response and the complex dielectric response calculated by the model;

[0035] The solving unit is used to solve the model, obtain the trend of the complex dielectric response of the insulating paper as it changes with moisture and angular frequency, and form a moisture-frequency domain dielectric spectrum database of the insulating paper.

[0036] According to a third aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps of any of the above methods are implemented.

[0037] According to a fourth aspect of the present invention, there is provided a computer program product comprising a computer program or instructions, which implement the steps of any of the above methods when executed by a processor.

[0038] In general, compared with the prior art, the above technical solutions conceived by the present invention mainly have the following beneficial effects.

[0039] 1. The present invention constructs a moisture-frequency three-dimensional dielectric model of insulating paper, which sets a complex dielectric response calculation constraint, a jump conductivity calculation constraint, and a relaxation time calculation constraint for the low-frequency relaxation polarization process. Among them, the complex dielectric response calculation constraint can fully express the real change process of the dielectric response of the insulating paper with angular frequency, and the jump conductivity calculation constraint and the low-frequency relaxation time calculation constraint can accurately reflect the influence of water content on the complex dielectric response. Combining the above constraints, a moisture-frequency three-dimensional dielectric model that accurately reflects the change of dielectric response with angular frequency and water content can be constructed. Based on this model, a small amount of experimental data can be used to determine the change law of the physical parameters corresponding to the frequency-domain dielectric response of the insulating paper with moisture, and then reconstruct the moisture-frequency domain dielectric spectrum database of the insulating paper, so as to quickly and accurately obtain the dielectric spectrum of insulating paper with any different moisture content. Compared with traditional data interpolation processing, this method is based on dielectric response parameters with physical meaning, and provides an efficient and reliable data acquisition tool for the study of dielectric properties related to moisture content of insulating paper.

[0040] 2. Furthermore, the present invention preferably uses a simulated annealing algorithm for solving, which can jump out of the local optimum in the high-temperature stage and converge finely in the low-temperature stage, and can achieve efficient global optimization and reliable convergence of complex, multi-peak high-dimensional parameter spaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a flowchart of the steps of a method for constructing a frequency domain dielectric spectrum database in one embodiment of the present invention;

[0042] Figure 2 is the frequency domain dielectric spectrum of the insulating paper at different moisture contents obtained by laboratory measurement in one embodiment of the present invention;

[0043] Figure 3 is a curve showing the change of the objective function value with the number of iterations during the solution process of the simulated annealing algorithm in one embodiment of the present invention;

[0044] Figure 4 The insulation paper moisture-frequency domain dielectric spectrum database in one embodiment of the present invention;

[0045] Figure 5 This is a comparison result of the measured dielectric spectrum of the insulating paper with a moisture content of 3.58% provided by an embodiment of the present invention and the dielectric spectrum calculated in the database. DETAILED DESCRIPTION

[0046] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0047] Example 1

[0048] The present invention provides a method for constructing an insulating paper moisture-frequency domain dielectric spectrum database, such as Figure 1 FIG. 1 is a flowchart of a method for constructing a frequency domain dielectric spectrum database according to an embodiment of the present invention, which includes:

[0049] S1. A moisture-frequency three-dimensional dielectric model is constructed based on the sample parameters of different insulating paper samples. The sample parameters include the moisture content of the sample, the angular frequency of the external electric field applied when measuring the complex dielectric response, and the measured complex dielectric response of the sample. The model includes constraints and objective functions. The constraints include complex dielectric response calculation constraints, jump conductivity calculation constraints, and low-frequency relaxation time calculation constraints of the low-frequency relaxation polarization process; the complex dielectric response calculation constraints characterize the complex dielectric response of the insulating paper, including at least the optical frequency dielectric constant, the complex dielectric response of the jump conductivity process, the complex dielectric response of the low-frequency relaxation polarization process, and the complex dielectric response of the high-frequency relaxation polarization process; the jump conductivity calculation constraints characterize the jump conductivity including the exponential value of the quadratic equation of moisture content, and the low-frequency relaxation time calculation constraints characterize the relaxation time of the low-frequency relaxation polarization process including the exponential value of the quadratic equation of moisture content; the objective function is to minimize the deviation between the measured complex dielectric response and the complex dielectric response calculated by the model.

[0050] S2. Solve the model to obtain the trend of the complex dielectric response of the insulating paper as it changes with moisture and angular frequency, and form a moisture-frequency domain dielectric spectrum database for the insulating paper.

[0051] The following is a detailed introduction to the steps.

[0052] It is understandable that before building the model, it is necessary to first obtain the sample parameters of different insulating paper samples, and the acquisition process is as follows.

[0053] S01. Prepare insulating paper samples with different moisture contents.

[0054] S011: Place the insulating paper sample in a vacuum drying oven at 90°C and 50Pa for 24 hours to remove moisture.

[0055] S012: Take out the dried insulation paper sample and place it in a constant temperature and humidity chamber. Adjust the relative humidity of the chamber according to the expected moisture content.

[0056] S013: The sample is kept in a constant temperature and humidity chamber for 12 hours to ensure that the moisture distribution of the sample is uniform and stable and to achieve moisture balance;

[0057] S014: Repeat steps S11 to S13 to adjust the humidity to prepare insulating paper samples with different moisture contents.

[0058] S02. Measure the frequency domain dielectric spectrum of the insulating paper sample.

[0059] S021: Place the insulating paper sample into a three-electrode test device, seal the device, and place it in a constant temperature box for 12 hours to ensure that the sample is under stable moisture and temperature for testing;

[0060] S022: Measure the complex capacitance C of insulating paper samples using a frequency domain dielectric tester * mea (ω), the frequency domain dielectric spectrum ε of the complex dielectric constant is calculated based on the complex capacitance * mea (ω), and record the real part of the insulation paper ε' mea (ω) and the imaginary part ε” mea (ω) data, which is measured data;

[0061] The calculation formula for the frequency domain dielectric spectrum of the complex dielectric constant based on the complex capacitance is:

[0062] C * mea (ω)=C0·ε * mea (ω)=C0·[ε' mea (ω)-jε” mea (ω)] (1);

[0063] Where C0 is the geometric capacitance, which is determined by the geometric dimensions of the cardboard being tested, and ω is the angular frequency used for frequency domain dielectric testing.

[0064] S023: Repeat steps S021 and S022 to obtain the frequency domain dielectric spectrum data ε' of the insulating paper with different moisture contents X mea (ω,X) and ε” mea (ω,X).

[0065] Based on the above data, we can proceed to steps S1 to S2 to build a moisture-frequency domain dielectric spectrum database for insulating paper.

[0066] Step S1 is a modeling process, and the model involves an objective function and constraints.

[0067] The constraints include the calculation constraints for the complex dielectric response, the calculation constraints for the jump conductivity, and the calculation constraints for the low-frequency relaxation time of the low-frequency relaxation polarization process. Each constraint is introduced below.

[0068] The complex dielectric response calculation constraints characterizing the complex dielectric response of the insulating paper include at least the optical frequency dielectric constant, the complex dielectric response of the hopping conductivity process, the complex dielectric response of the low-frequency relaxation polarization process, and the complex dielectric response of the high-frequency relaxation polarization process.

[0069] This paper analyzes the dielectric behavior of insulating paper. Both the real and imaginary parts of the complex dielectric response progress through a series of jump conductance, low-frequency relaxation polarization, and high-frequency relaxation polarization processes as angular frequency increases. It should be noted that the terms "low-frequency" and "high-frequency" are relative, indicating that the relaxation polarization process exhibits two distinct trends in different frequency bands, and that there is no absolute range for these values.

[0070] Based on the above analysis, the present invention sets calculation constraints for the complex dielectric response, and characterizes the complex dielectric response of the insulating paper, including at least the optical frequency dielectric constant, the complex dielectric response of the jump conductivity process, the complex dielectric response of the low-frequency relaxation polarization process, and the complex dielectric response of the high-frequency relaxation polarization process. This can fully express the true change process of the dielectric response of the insulating paper with angular frequency, thereby improving the accuracy of modeling.

[0071] If only the variation of dielectric response with angular frequency is considered, the complex dielectric response of insulating paper can be expressed as a single variable dielectric process in the following form:

[0072]

[0073] Where, ε * paper (ω) is the complex dielectric response of the insulating paper at angular frequency ω, ε ∞ is the optical frequency dielectric constant, which is 8.854×10 -12 F / m, ε * hop (ω) is the complex dielectric response of the jump conductance process, ε * p1 (ω) is the complex dielectric response of the low-frequency relaxation polarization process, ε * p2 (ω) is the complex dielectric response of the high-frequency relaxation polarization process;

[0074] σ hop is the hopping conductivity, ε0 is the vacuum dielectric constant, s is the shape parameter of the hopping conductivity process, Δε1 and τ1 are the low-frequency relaxation polarization intensity and low-frequency relaxation time, Δε2 and τ2 are the high-frequency relaxation polarization intensity and high-frequency relaxation time, α1, α2, β1 and β2 are the shape parameters of the corresponding relaxation polarization process.

[0075] Furthermore, the present invention also analyzes the variation trend of the above processes with the moisture content, and finds that with the increase of moisture content, the dielectric curves of the jump conductivity process and the low-frequency relaxation polarization process of the insulating paper gradually shift to the high-frequency direction and keep the curve shape basically unchanged. Specifically, with the increase of moisture content, the jump conductivity σ hop increases, the relaxation time τ1 decreases, while the high-frequency relaxation polarization process is almost unaffected. Moreover, the dielectric parameter σ hop Both τ and τ1 show significant exponential variation characteristics with the moisture content X, and their quantitative relationship conforms to the quadratic-exponential mixing function.

[0076] Based on the above analysis, the present invention further sets the jump conductivity calculation constraint and the relaxation time calculation constraint of the low-frequency relaxation polarization process. The jump conductivity calculation constraint characterizes the exponential value of the quadratic equation of the jump conductivity including the water content, and the low-frequency relaxation time calculation constraint characterizes the exponential value of the quadratic equation of the relaxation time of the low-frequency relaxation polarization process including the water content. This can accurately reflect the true change trend of the complex dielectric response of the insulating paper with the moisture content, thereby improving the accuracy of the modeling.

[0077] Specifically, in the calculation constraint of jump conductivity, considering the influence of water content, the expression of jump conductivity can be expressed as:

[0078] σ hop (X) = exp(a1·X 2 +b1·X+c1)(3);

[0079] Where X is the water content, σ hop (X) is the jump conductivity of the insulating paper with a moisture content of X, and a1, b1, and c1 are the undetermined coefficients of the corresponding quadratic equation.

[0080] It is understandable that fine-tuning can be performed on the basis of the above expression, such as adding a slight correction factor, etc., as long as its main structure is still the quadratic-exponential mixed function as above.

[0081] At this point, considering the influence of water content, the expression of the complex dielectric response of the jump conductivity process can be updated as follows:

[0082]

[0083] Where, ε * hop (ω,X) is the complex dielectric response of the insulating paper with a moisture content of X during the conductance jump process at an angular frequency of ω.

[0084] Specifically, in the low-frequency relaxation time calculation constraint, considering the influence of water content, the relaxation time expression of the low-frequency relaxation polarization process can be:

[0085] τ1(X)=exp(a2·X 2 +b2·X+c2)(5);

[0086] Where X is the moisture content, τ1(X) is the relaxation time of the low-frequency relaxation polarization process of the insulating paper with a moisture content of X, and a2, b2, and c2 are the unknown coefficients of the corresponding quadratic equation.

[0087] It is understandable that fine-tuning can be performed on the basis of the above expression, such as adding a slight correction factor, etc., as long as its main structure is still the quadratic-exponential mixed function as above.

[0088] At this point, considering the influence of water content, the expression of the complex dielectric response of the low-frequency relaxation polarization process can be updated as follows:

[0089]

[0090] Where, ε * p1 (ω,X) is the complex dielectric response of the insulating paper with a moisture content of X during the low-frequency relaxation polarization process at an angular frequency of ω.

[0091] Since the high-frequency relaxation polarization process is almost unaffected by the water content, the expression of the complex dielectric response of the high-frequency relaxation polarization process remains as follows:

[0092]

[0093] Therefore, considering the influence of water content, the single-variable dielectric process of equation (2) can be expressed as a two-variable dielectric process, that is, as follows:

[0094]

[0095] Where, ε * paper (ω,X) is the complex dielectric response of insulating paper with moisture content X at angular frequency ω.

[0096] In a specific embodiment, considering the influence of water content, the constraints of the model can be expressed as:

[0097]

[0098] At this time, there are 15 parameters to be optimized introduced by the above constraints, including the optical frequency dielectric constant ε ∞ ; s, a1, b1, c1 of the hopping conductance process; Δε1, α1, β1, a2, b2, c2 of the low-frequency relaxation polarization process; and Δε2, τ2, α2, β2 of the high-frequency relaxation polarization process.

[0099] The objective function of the model is to minimize the deviation between the measured complex dielectric response and the complex dielectric response calculated by the model.

[0100] Specifically, the parameter optimization algorithm is executed according to the objective function to minimize the deviation between the two, and the optimized parameters are output. The obtained parameters are substituted into the complex dielectric response function of the insulating paper to obtain the trend of the complex dielectric response of the insulating paper with moisture and angular frequency, thus forming a moisture-frequency domain dielectric spectrum database of the insulating paper.

[0101] In one embodiment, the deviation between the measured complex dielectric response and the complex dielectric response calculated by the model can be directly calculated, and then a parameter optimization algorithm is executed to minimize the deviation and output the optimized parameters.

[0102] In another embodiment, the dielectric response may be logarithmically processed before the deviation is calculated. The specific expression is as follows:

[0103]

[0104] Where θ is the deviation, n is the number of frequency points measured, X is the water content, ω is the angular frequency, ε' paper (ω,X) and ε” paper (ω, X) are the real and imaginary parts of the complex dielectric response of the insulating paper with a moisture content of X at an angular frequency ω, respectively, output by the model. ε' mea (ω,X) and ε” mea (ω,X) are the real and imaginary parts of the measured complex dielectric response of the insulating paper with a moisture content of X at an angular frequency ω.

[0105] Combining the above processes, the modeling process is completed.

[0106] Then, enter step S2:

[0107] By executing a parameter optimization algorithm on the model and outputting the optimized parameters, the obtained parameters are substituted into the complex dielectric response function of the insulating paper to obtain the trend of the complex dielectric response of the insulating paper as the moisture content and angular frequency change, thus forming a moisture-frequency domain dielectric spectrum database for the insulating paper.

[0108] Specifically, the parameter optimization algorithm may adopt a traditional simulated annealing algorithm, or may adopt a genetic algorithm, particle swarm optimization or other algorithms.

[0109] The parameters to be optimized are recorded as the parameter matrix to be optimized M. The optimization process is described below using the simulated annealing algorithm as an example.

[0110] S21, set the initial value M0 of the parameter matrix to be optimized; the initial temperature T0; the end temperature T min ; Cooling rate λ; Maximum number of iterations at each temperature L max .

[0111] S22, according to the current parameter matrix M current Calculate the perturbation matrix ΔM and generate a new parameter matrix M based on the perturbation matrix ΔM new .

[0112] The calculation formula of the perturbation matrix ΔM is:

[0113] ΔM=M current ·R·S (11);

[0114] Where R is a random vector that obeys the standard normal distribution and has the same dimension as the coefficient matrix; S is the preset disturbance amplitude.

[0115] Parameter matrix M new The calculation formula is:

[0116] M new =M current +ΔM(12).

[0117] S23, calculate M respectively current 、M new The deviation θ(M current ),θ(M new ):

[0118] If θ(M new )<θ(M current ), then receive the new solution M new , with a new interpretation of M new as the new current parameter matrix;

[0119] Otherwise, generate a random number η∈[0,1] and calculate the probability P: If P>η, then accept M new , with a new interpretation of M new As the new current parameter matrix, otherwise keep the current parameter matrix M current constant.

[0120] The calculation formula of probability P is:

[0121]

[0122] Where, Δθ=θ(M new )-θ(M current ), T current is the current temperature.

[0123] S24, at the current temperature T current Repeat steps S22 to S23 until the parameter matrix is not updated for a preset number of iterations or the number of iterations reaches the maximum number of iterations L. max .

[0124] S25: Lower the temperature to the new temperature T new As the current temperature, repeat steps S22 to S25. When the temperature drops to the end temperature T min The optimization process is terminated when . Output the optimal parameter matrix M best , which is the result of parameter identification.

[0125] The formula for reducing temperature is:

[0126] T new =T current ·λ (14).

[0127] Finally, the optimal parameters obtained by S2 are input into the model, and the model is reconstructed to obtain the moisture-frequency domain dielectric spectrum database of the insulating paper. The database can output the corresponding insulating paper spectrum according to the input moisture content.

[0128] Example 2

[0129] The present invention also relates to a system for constructing an insulating paper moisture-frequency domain dielectric spectrum database, comprising:

[0130] A parameter acquisition unit is used to obtain sample parameters of different insulating paper samples, the sample parameters including the moisture content of the sample, the angular frequency of the applied electric field when measuring the complex dielectric response, and the measured complex dielectric response of the sample;

[0131] A modeling unit is used to construct a moisture-frequency three-dimensional dielectric model based on sample parameters of different insulating paper samples, the model including constraints and objective functions, the constraints including complex dielectric response calculation constraints, jump conductivity calculation constraints, and low-frequency relaxation time calculation constraints of low-frequency relaxation polarization process; the complex dielectric response calculation constraints characterize the complex dielectric response of the insulating paper, including at least the optical frequency dielectric constant, the complex dielectric response of the jump conductivity process, the complex dielectric response of the low-frequency relaxation polarization process, and the complex dielectric response of the high-frequency relaxation polarization process; the jump conductivity calculation constraints characterize the jump conductivity including the exponential value of the quadratic equation of moisture content, and the low-frequency relaxation time calculation constraints characterize the relaxation time of the low-frequency relaxation polarization process including the exponential value of the quadratic equation of moisture content; the objective function is to minimize the deviation between the measured complex dielectric response and the complex dielectric response calculated by the model;

[0132] The solving unit is used to solve the model, obtain the trend of the complex dielectric response of the insulating paper as it changes with moisture and angular frequency, and form a moisture-frequency domain dielectric spectrum database of the insulating paper.

[0133] Specifically, the specific manner in which each unit implements the corresponding function can be referred to the introduction of Example 1, which will not be repeated here.

[0134] Example 3

[0135] The present invention also relates to a computer-readable storage medium having a computer program stored thereon, which implements the steps of the method in embodiment 1 when the computer program is executed by a processor.

[0136] Specifically, the memory may include a high-speed random access memory, and may also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart media card (SX), a secure digital (SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage device.

[0137] Example 4

[0138] An embodiment of the present invention provides a computer program product or computer program, which includes computer instructions stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the computer device to perform the steps of the method of Embodiment 1 of the present invention.

[0139] The technical features of the above embodiments can be combined in any manner. To simplify the description, 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. It should be noted that the phrases "in one embodiment", "for example", "and another example", etc. of the present invention are intended to illustrate the present invention and are not intended to limit the present invention.

[0140] Example 5

[0141] In this example, cellulose-based insulating paperboard with a thickness of 1mm was selected as the test object. The insulating paper sample was placed in a vacuum drying oven, set at a temperature of 90°C, and dried in a vacuum environment of 50Pa for 24 hours to remove moisture from the insulating paper. After drying, the sample was placed in a constant temperature and humidity chamber, and the relative humidity of the chamber was adjusted according to the expected moisture content. It was kept for 12 hours to ensure that the moisture in the sample was evenly distributed and moisture balance was achieved. This process was repeated to prepare insulating paper samples with seven different moisture contents: 0.52%, 1.48%, 2.34%, 3.26%, 4.30%, 5.35%, and 6.48%;

[0142] Insulating paper samples with different moisture contents were placed in a three-electrode test device, sealed, and placed in a 75°C constant temperature box to ensure that the samples were tested under stable moisture and temperature conditions. A dielectric impedance spectrometer was used to measure the frequency domain dielectric spectrum of the samples. In this embodiment, the test voltage was 200V. peakThe measurement frequency range is 1mHz to 10kHz, covering 7 orders of magnitude frequency bands to fully reflect the dielectric properties of paper insulation. The complex capacitance C of the insulating paper sample is measured using a frequency domain dielectric tester. * mea (ω), calculate the frequency domain dielectric spectrum data ε' under different moisture contents mea (ω,X) and ε” mea (ω, X), the dielectric spectrum measurement results of insulating paper with different moisture contents at 75℃ are as follows Figure 2 As shown, (a) is the real part change trend diagram of the dielectric spectrum under different water contents, and (b) is the imaginary part change trend diagram of the dielectric spectrum under different water contents.

[0143] Based on the above parameters, a moisture-frequency three-dimensional dielectric model is constructed and solved.

[0144] This embodiment uses the simulated annealing algorithm to solve, with the initial temperature T0=10; the end temperature T min =10 -6 ; Cooling rate λ = 0.98; Maximum number of iterations at each temperature L max =1000; the perturbation amplitude S is set to 0.006. The curve of the objective function deviation value changing with the number of iterations in the simulated annealing algorithm is as follows: Figure 3 As shown in the figure, with the increase of the number of iterations, it can be seen that the fluctuation of the deviation value gradually decreases and tends to be stable, which illustrates the convergence and effectiveness of the annealing algorithm in the parameter identification of the three-dimensional dielectric model of insulating paper.

[0145] The parameters obtained are shown in Table 1 below.

[0146] Table 1

[0147]

[0148]

[0149] Using the optimal parameters shown in Table 1, we substitute them into the model equation (8) to reconstruct the dielectric spectrum data that varies with water content and angular frequency, thus obtaining: Figure 4 The complete insulation paper moisture-frequency domain dielectric spectrum database is shown, where (a) is the real part change surface of the dielectric spectrum, and (b) is the imaginary part change surface of the dielectric spectrum.

[0150] Figure 5 The comparison results of the measured dielectric spectrum of insulating paper with a moisture content of 3.58% and the dielectric spectrum calculated from the database are shown, where (a) is the comparison result of the real part of the complex dielectric constant, and (b) is the comparison result of the imaginary part of the complex dielectric constant. The calculated spectrum is in good agreement with the measured spectrum, verifying the accuracy of the constructed moisture-frequency domain dielectric spectrum database.

[0151] Overall, this invention provides a method for constructing a database of dielectric spectra in the moisture-frequency domain for insulating paper. By building a three-dimensional dielectric model of insulating paper based on moisture-frequency, this method allows for rapid and accurate acquisition of dielectric spectra of insulating paper at various moisture contents, relying solely on a small amount of experimental data. This database not only provides an efficient data acquisition method for laboratory research but also lays the foundation for further research into the dielectric properties of insulating paper at varying moisture contents.

[0152] The above embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A method for constructing an insulating paper moisture-frequency domain dielectric spectrum database, characterized in that: include: Constructing a moisture-frequency three-dimensional dielectric model based on sample parameters of different insulating paper samples, wherein the sample parameters include the moisture content of the sample, the angular frequency of the applied electric field when measuring the complex dielectric response, and the measured complex dielectric response of the sample; Solving the model, obtaining the trend of the complex dielectric response of the insulating paper as a function of moisture and angular frequency, and forming a moisture-frequency domain dielectric spectrum database of the insulating paper; The model includes constraints and objective functions, wherein the constraints include complex dielectric response calculation constraints, jump conductivity calculation constraints, and relaxation time calculation constraints for low-frequency relaxation polarization processes; the complex dielectric response calculation constraints characterize the complex dielectric response of the insulating paper, including at least the optical frequency dielectric constant, the complex dielectric response of the jump conductivity process, the complex dielectric response of the low-frequency relaxation polarization process, and the complex dielectric response of the high-frequency relaxation polarization process; the jump conductivity calculation constraints characterize the jump conductivity including the exponential value of a quadratic equation of water content, and the low-frequency relaxation time calculation constraints characterize the relaxation time of the low-frequency relaxation polarization process including the exponential value of a quadratic equation of water content; and the objective function is to minimize the deviation between the measured complex dielectric response and the complex dielectric response calculated by the model.

2. The method for constructing an insulating paper moisture-frequency domain dielectric spectrum database according to claim 1, characterized in that: In the complex dielectric response calculation constraints: The complex dielectric response of the jump conductance process is expressed as: Where X is the water content, ω is the angular frequency, ε * hop (ω,X) is the complex dielectric response of the insulating paper with a moisture content of X during the jump conductance process at an angular frequency of ω, σ hop (X) is the jump conductivity of the insulating paper with a moisture content of X, ε0 is the vacuum dielectric constant, and s is the shape parameter of the jump conductivity process; The complex dielectric response of the low-frequency relaxation polarization process is expressed as: Where, ε * p1 (ω,X) is the complex dielectric response of the low-frequency relaxation polarization process of the insulating paper with a moisture content of X at an angular frequency of ω, Δε1 is the low-frequency relaxation polarization intensity, τ1(X) is the relaxation time of the low-frequency relaxation polarization process of the insulating paper with a moisture content of X, and α1 and β1 are the shape parameters of the low-frequency relaxation polarization process; The complex dielectric response of the high-frequency relaxation polarization process is expressed as: Where, ε * p2 (ω) is the complex dielectric response of the insulating paper in the high-frequency relaxation polarization process at the angular frequency ω, Δε2 is the high-frequency relaxation polarization intensity, τ2 is the relaxation time of the high-frequency relaxation polarization process, and α2 and β2 are the shape parameters of the high-frequency relaxation polarization process.

3. The method for constructing an insulating paper moisture-frequency domain dielectric spectrum database according to claim 1 or 2, characterized in that: In the jump conductivity calculation constraint, the jump conductivity expression is: Where X is the water content, σ hop (X) is the jump conductivity of the insulating paper with a moisture content of X, and a1, b1, and c1 are the undetermined coefficients of the corresponding quadratic equation.

4. The method for constructing an insulating paper moisture-frequency domain dielectric spectrum database according to claim 1 or 2, characterized in that: In the low-frequency relaxation time calculation constraint, the relaxation time of the low-frequency relaxation polarization process is expressed as: τ1(X)=exp(a2·X 2 +b2·X+c2); Where X is the moisture content, τ1(X) is the relaxation time of the low-frequency relaxation polarization process of the insulating paper with a moisture content of X, and a2, b2, and c2 are the unknown coefficients of the corresponding quadratic equation.

5. The method for constructing an insulating paper moisture-frequency domain dielectric spectrum database according to claim 1, characterized in that: The expression of the objective function is: Where n is the number of frequency points measured, X is the water content, ω is the angular frequency, ε' paper (ω,X) and ε” paper (ω, X) are the real and imaginary parts of the complex dielectric response of the insulating paper with a moisture content of X at an angular frequency ω output by the model, ε' mea (ω,X) and ε” mea (ω,X) are the real and imaginary parts of the measured complex dielectric response of the insulating paper with a moisture content of X at an angular frequency ω.

6. The method for constructing an insulating paper moisture-frequency domain dielectric spectrum database according to claim 1, characterized in that: The model is solved using a simulated annealing algorithm.

7. The method for constructing an insulating paper moisture-frequency domain dielectric spectrum database according to claim 1, characterized in that: Before building the model, sample parameters of different insulating paper samples are first obtained. The acquisition process includes: Preparation of insulation paper samples with different moisture contents; The complex dielectric responses of insulating paper samples with different moisture contents were measured at different angular frequencies.

8. A system for constructing a moisture-frequency domain dielectric spectrum database of insulating paper, characterized in that: include: A parameter acquisition unit is used to obtain sample parameters of different insulating paper samples, the sample parameters including the moisture content of the sample, the angular frequency of the applied electric field when measuring the complex dielectric response, and the measured complex dielectric response of the sample; A modeling unit is used to construct a moisture-frequency three-dimensional dielectric model based on sample parameters of different insulating paper samples, the model including constraints and objective functions, the constraints including complex dielectric response calculation constraints, jump conductivity calculation constraints, and low-frequency relaxation time calculation constraints of low-frequency relaxation polarization process; the complex dielectric response calculation constraints characterize the complex dielectric response of the insulating paper, including at least the optical frequency dielectric constant, the complex dielectric response of the jump conductivity process, the complex dielectric response of the low-frequency relaxation polarization process, and the complex dielectric response of the high-frequency relaxation polarization process; the jump conductivity calculation constraints characterize the jump conductivity including the exponential value of the quadratic equation of moisture content, and the low-frequency relaxation time calculation constraints characterize the relaxation time of the low-frequency relaxation polarization process including the exponential value of the quadratic equation of moisture content; the objective function is to minimize the deviation between the measured complex dielectric response and the complex dielectric response calculated by the model; The solving unit is used to solve the model, obtain the trend of the complex dielectric response of the insulating paper as it changes with moisture and angular frequency, and form a moisture-frequency domain dielectric spectrum database of the insulating paper.

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

10. A computer program product comprising a computer program or instructions, characterized in that When the computer program or instruction is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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