Method, system and device for evaluating moisture degree of metal oxide lightning arrester

Abstract

The invention discloses an evaluation method, system and device for the moisture degree of a metal oxide arrester, and the method comprises the steps: applying an alternating voltage to a zinc oxide arrester, measuring the zinc oxide arrester based on an FDS frequency domain dielectric spectrum tester, and obtaining a distributed frequency domain dielectric spectrum of the zinc oxide arrester; analyzing the distributed frequency domain dielectric spectrum to obtain a complex relative dielectric constant, and further obtaining a dielectric modulus; the dielectric modulus and the complex relative dielectric constant are fitted based on a Havriliak-Negami model, and a relaxation peak curve is obtained; and based on the relationship between the moisture degree of the zinc oxide arrester and the relaxation peak curve, obtaining the influence degree of the Havriliak-Negami model function on the moisture degree of the zinc oxide arrester. The damping degree of the lightning arrester can be accurately evaluated, and a new thought is provided for improving the operation reliability of the distribution network lightning arrester.

Description

Technical Field

[0001] The invention belongs to the technical field of lightning arresters and relates to a method, system and device for evaluating the moisture degree of a metal oxide lightning arrester. Background Art

[0002] Metal oxide arresters are one of the key components of the power system network. In order to protect electrical equipment from overvoltage during power system operation, zinc oxide arresters have good nonlinear volt-ampere characteristics, good protection performance and current carrying capacity. However, when zinc oxide arresters are damp, they may cause overheating of the arrester, and their performance may be significantly reduced due to moisture. The degradation of zinc oxide arrester performance may affect the stable operation of the power system, the failure of power equipment, and the life risk of technicians. Therefore, it is necessary to regularly estimate the intrusion moisture content before it fails. Frequency domain dielectric spectroscopy FDS can effectively diagnose the conditions of various electrical equipment (such as transformers, XLPE cables, etc.), and is also an effective technology for monitoring the aging of zinc oxide arresters. However, the current research on the arrester status based on frequency domain dielectric spectroscopy FDS only stays at analyzing the qualitative changes of the FDS curve before and after aging, without quantitative analysis, which brings difficulties to the evaluation of the arrester status. Summary of the invention

[0003] The purpose of the present invention is to solve the problem that the study of the arrester status by the frequency domain dielectric spectroscopy method (FDS) in the prior art only stays at analyzing the qualitative changes of the FDS curve before and after aging, but does not quantitatively analyze the arrester status, and to provide a method, system and device for evaluating the moisture degree of metal oxide arresters.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for evaluating the moisture degree of a metal oxide surge arrester, comprising:

[0006] The mass of the zinc oxide arrester after being dampened and the mass of the original zinc oxide arrester sample are collected to obtain the dampness degree of the zinc oxide arrester;

[0007] Apply alternating voltage to the zinc oxide lightning arrester, measure the zinc oxide lightning arrester based on the FDS frequency domain dielectric spectrum tester, and obtain the distributed frequency domain dielectric spectrum of the zinc oxide lightning arrester;

[0008] The distributed frequency-domain dielectric spectrum is analyzed to obtain the complex relative dielectric constant;

[0009] Under the action of the alternating electric field of the medium, the dielectric modulus is obtained based on the complex relative dielectric constant;

[0010] The dielectric modulus and complex relative permittivity were fitted based on the Havriliak-Negami model to obtain the relaxation peak curve.

[0011] Based on the relationship between the moisture degree of zinc oxide arresters and the relaxation peak curve, the influence of the Havriliak-Negami model function on the moisture degree of zinc oxide arresters is obtained.

[0012] A further improvement of the present invention is:

[0013] Further, the moisture degree of the zinc oxide arrester is obtained, specifically:

[0014]

[0015] Among them, Δm is the difference between the mass of the zinc oxide arrester after being damp and the mass of the original zinc oxide arrester sample, m i is the mass of the i-th original zinc oxide arrester sample.

[0016] Furthermore, the distributed frequency-domain dielectric spectrum is analyzed to obtain the complex relative dielectric constant, which is:

[0017] Apply alternating voltage to zinc oxide arrester The corresponding current through the medium for:

[0018]

[0019] Among them, C′(ω) and C″(ω) represent the real and imaginary parts of the complex capacitance of the dielectric medium, respectively; C0, ε′(ω), ε”(ω) are the geometric capacitance and the real and imaginary parts of the complex relative permittivity of the dielectric medium, respectively; the real part ε′(ω) of the complex relative permittivity is the energy storage component; the imaginary part ε”(ω) is further expressed as:

[0020]

[0021] Among them, ε′ r ′(ω) is the dielectric relaxation component, is the conduction loss.

[0022] Furthermore, under the action of the alternating electric field of the medium, the dielectric modulus is obtained based on the complex relative dielectric constant. Specifically, under the action of the alternating electric field of the medium, when the frequency of the electric field is low, free charges will accumulate around the electrode, resulting in a higher dielectric constant at a lower frequency, resulting in an electrode polarization effect; the high dielectric constant caused by electrode polarization is mutually related to dielectric relaxation, and the dielectric modulus is the inverse of the complex relative dielectric constant, defined as:

[0023]

[0024] Among them, M′(ω) and M″(ω) are the real and imaginary parts of the dielectric modulus, respectively, which can be further expressed by the complex relative permittivity as follows:

[0025]

[0026] Among them, it can be seen from formula (4) and formula (5) that the dielectric modulus minimizes the change in conductivity value at low frequency.

[0027] Furthermore, under the action of the alternating electric field of the medium, the dielectric modulus is obtained based on the complex relative dielectric constant, and it also includes: under the low frequency state, the influence of the loss caused by the dielectric relaxation phenomenon on the conduction loss is negligible, and the conduction loss is estimated by modifying formula (2). Under the low frequency state, formula (2) is written as formula (6):

[0028]

[0029] In the low frequency state, the DC conductivity σ0 is obtained by formula (6); given the DC conductivity σ0, The conduction loss in the high frequency state is obtained, and then the loss caused by dielectric relaxation is calculated using formula (2).

[0030] Furthermore, the dielectric modulus and complex relative permittivity are fitted based on the Havriliak-Negami model to obtain the relaxation peak curve. Specifically, the dielectric relaxation process is analyzed based on the Havriliak-Negami model function:

[0031]

[0032] Among them, M s is the static dielectric modulus, M ∞ is the high frequency dielectric modulus, τ hn is the relaxation time constant, α represents the shape parameter of the symmetric distribution of the relaxation mechanism, and β represents the shape parameter of the asymmetric distribution of the relaxation mechanism. M′(ω) increases with the increase of the measurement frequency. The value of M″(ω) first increases and then decreases with the change of frequency. The peak value reached by M″(ω) with the change of frequency is called the “relaxation peak”.

[0033] Furthermore, the influence of the Havriliak-Negami model function on the moisture degree of the zinc oxide arrester is obtained, specifically:

[0034] C(%)=k 00 +k 10 ×α+k 01 ×β+k 20 ×α 2 +k 02 ×β 2 (8)

[0035] Among them, k 00 , k 10, k 01 , k 20 and k 02 are all constants.

[0036] A system for evaluating the moisture level of a metal oxide surge arrester, comprising:

[0037] A collection module, wherein the collection module collects the mass of the zinc oxide lightning arrester after being damp and the mass of the original zinc oxide lightning arrester sample to obtain the degree of dampness of the zinc oxide lightning arrester;

[0038] A first acquisition module, wherein the first acquisition module applies an alternating voltage to the zinc oxide lightning arrester, measures the zinc oxide lightning arrester based on an FDS frequency domain dielectric spectrum tester, and acquires a distributed frequency domain dielectric spectrum of the zinc oxide lightning arrester;

[0039] An analysis module, wherein the analysis module analyzes the distributed frequency domain dielectric spectrum to obtain a complex relative dielectric constant;

[0040] A dielectric modulus acquisition module, wherein the dielectric modulus acquisition module obtains the dielectric modulus based on the complex relative dielectric constant under the action of the medium alternating electric field;

[0041] A fitting module, wherein the fitting module fits the dielectric modulus and the complex relative permittivity based on the Havriliak-Negami model to obtain a relaxation peak curve;

[0042] The second acquisition module obtains the influence of the Havriliak-Negami model function on the moisture degree of the zinc oxide arrester based on the relationship between the moisture degree of the zinc oxide arrester and the relaxation peak curve.

[0043] A terminal device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above method when executing the computer program.

[0044] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the above method are implemented.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] The present invention applies an alternating voltage to a zinc oxide lightning arrester, measures the zinc oxide lightning arrester based on an FDS frequency domain dielectric spectrum tester, and obtains a distributed frequency domain dielectric spectrum of the zinc oxide lightning arrester; then analyzes the distributed frequency domain dielectric spectrum to obtain a complex relative dielectric constant, and then obtains a dielectric modulus; fits the dielectric modulus and the complex relative dielectric constant based on the Havriliak-Negami model to obtain a relaxation peak curve; based on the relationship between the moisture level of the zinc oxide lightning arrester and the relaxation peak curve, obtains the influence of the Havriliak-Negami model function on the moisture level of the zinc oxide lightning arrester. The present invention performs FDS measurement on the zinc oxide lightning arrester under different moisture levels to obtain the frequency change of the real part and the imaginary part of the dielectric modulus. The Havriliak-Negami model is used to fit the relationship between the real part and the imaginary part of the dielectric modulus under different moisture levels, and obtains a function of the Havriliak-Negami model parameters changing with the moisture level. The present invention can accurately evaluate the moisture degree of the lightning arrester, and provides a new idea for improving the operating reliability of the distribution network lightning arrester. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0048] Figure 1 It is a schematic flow chart of a method for evaluating the moisture degree of a metal oxide surge arrester according to the present invention;

[0049] Figure 2 It is a schematic diagram of the structure of the evaluation system for the moisture degree of metal oxide surge arresters of the present invention;

[0050] Figure 3 It is a schematic diagram of the corresponding relationship between the relaxation peak and the degree of moisture;

[0051] Figure 4 It is a schematic diagram of the corresponding relationship between the HN model parameter α and the degree of moisture;

[0052] Figure 5 It is a schematic diagram of the corresponding relationship between the HN model parameter β and the degree of moisture;

[0053] Figure 6 is the HN model parameter τ hn Schematic diagram of the corresponding relationship with the degree of moisture. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0055] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. 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.

[0056] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0057] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0058] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0059] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0060] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0061] See also Figure 1 The present invention discloses a method for evaluating the moisture degree of a metal oxide surge arrester, comprising:

[0062] S101, collecting the mass of the zinc oxide lightning arrester after being dampened and the mass of the original zinc oxide lightning arrester sample to obtain the dampness degree of the zinc oxide lightning arrester;

[0063] Get the moisture level of the zinc oxide arrester, specifically:

[0064]

[0065] Among them, Δm is the difference between the mass of the zinc oxide arrester after being damp and the mass of the original zinc oxide arrester sample, m i is the mass of the i-th original zinc oxide arrester sample.

[0066] S102, applying an alternating voltage to the zinc oxide lightning arrester, measuring the zinc oxide lightning arrester based on an FDS frequency domain dielectric spectrum tester, and obtaining a distributed frequency domain dielectric spectrum of the zinc oxide lightning arrester;

[0067] S103, analyzing the distributed frequency domain dielectric spectrum to obtain a complex relative dielectric constant;

[0068] The distributed frequency-domain dielectric spectrum is analyzed to obtain the complex relative dielectric constant, which is:

[0069] Apply alternating voltage to zinc oxide arrester The corresponding current through the medium for:

[0070]

[0071] Among them, C′(ω) and C″(ω) represent the real and imaginary parts of the complex capacitance of the dielectric medium, respectively; C0, ε′(ω), ε”(ω) are the geometric capacitance and the real and imaginary parts of the complex relative permittivity of the dielectric medium, respectively; the real part ε′(ω) of the complex relative permittivity is the energy storage component; the imaginary part ε”(ω) is further expressed as:

[0072]

[0073] Among them, ε′ r ′(ω) is the dielectric relaxation component, is the conduction loss.

[0074] S104, obtaining a dielectric modulus based on a complex relative dielectric constant under the action of an alternating electric field of the medium;

[0075] Under the action of the alternating electric field of the medium, when the frequency of the electric field is low, free charges will accumulate around the electrode, resulting in a higher dielectric constant at a lower frequency, resulting in an electrode polarization effect; the high dielectric constant caused by electrode polarization is mutually exclusive with dielectric relaxation, and the dielectric modulus is the inverse of the complex relative dielectric constant, defined as:

[0076]

[0077] Where M′(ω) and M″(ω) are the real and imaginary parts of the dielectric modulus, respectively, which can be further expressed as the complex relative permittivity:

[0078]

[0079] Among them, it can be seen from formula (4) and formula (5) that the dielectric modulus minimizes the change in conductivity value at low frequency.

[0080] Under the action of the alternating electric field of the medium, the dielectric modulus is obtained based on the complex relative dielectric constant, and it also includes: Under low-frequency conditions, the influence of the loss caused by the dielectric relaxation phenomenon on the conduction loss is negligible, and the conduction loss is estimated by modifying formula (2). Under low-frequency conditions, formula (2) is written as formula (6):

[0081]

[0082] In the low frequency state, the DC conductivity σ0 is obtained by formula (6); given the DC conductivity σ0, The conduction loss in the high frequency state is obtained, and then the loss caused by dielectric relaxation is calculated using formula (2).

[0083] S105, fitting the dielectric modulus and complex relative permittivity based on the Havriliak-Negami model to obtain the relaxation peak curve;

[0084] The dielectric relaxation process is analyzed based on the Havriliak-Negami model function:

[0085]

[0086] Among them, M s is the static dielectric modulus, M ∞ is the high frequency dielectric modulus, τ hn is the relaxation time constant, α represents the shape parameter of the symmetric distribution of the relaxation mechanism, and β represents the shape parameter of the asymmetric distribution of the relaxation mechanism. M′(ω) increases with the increase of the measurement frequency. The value of M″(ω) first increases and then decreases with the change of frequency. The peak value reached by M″(ω) with the change of frequency is called the “relaxation peak”.

[0087] S106, based on the relationship between the moisture degree of the zinc oxide arrester and the relaxation peak curve, obtaining the influence of the Havriliak-Negami model function on the moisture degree of the zinc oxide arrester.

[0088] C(%)=k 00 +k 10 ×α+k 01 ×β+k 20 ×α 2 +k 02 ×β 2 (8)

[0089] Among them, k 00 , k 10 , k 01 , k 20 and k 02 are all constants.

[0090] See also Figure 2 The present invention discloses a system for evaluating the moisture degree of a metal oxide arrester, comprising:

[0091] A collection module, wherein the collection module collects the mass of the zinc oxide lightning arrester after being damp and the mass of the original zinc oxide lightning arrester sample to obtain the degree of dampness of the zinc oxide lightning arrester;

[0092] A first acquisition module, wherein the first acquisition module applies an alternating voltage to the zinc oxide lightning arrester, measures the zinc oxide lightning arrester based on an FDS frequency domain dielectric spectrum tester, and acquires a distributed frequency domain dielectric spectrum of the zinc oxide lightning arrester;

[0093] An analysis module, wherein the analysis module analyzes the distributed frequency domain dielectric spectrum to obtain a complex relative dielectric constant;

[0094] A dielectric modulus acquisition module, wherein the dielectric modulus acquisition module obtains the dielectric modulus based on the complex relative dielectric constant under the action of the medium alternating electric field;

[0095] A fitting module, wherein the fitting module fits the dielectric modulus and the complex relative permittivity based on the Havriliak-Negami model to obtain a relaxation peak curve;

[0096] The second acquisition module obtains the influence of the Havriliak-Negami model function on the moisture degree of the zinc oxide arrester based on the relationship between the moisture degree of the zinc oxide arrester and the relaxation peak curve.

[0097] Example:

[0098] The present invention discloses a method for evaluating the moisture degree of a metal oxide arrester, comprising:

[0099] The present invention uses frequency domain spectroscopy (FDS) to measure the dielectric properties of zinc oxide lightning arrester samples with different moisture levels. The moisture level C% of the zinc oxide lightning arrester is expressed by formula (1).

[0100]

[0101] Among them, Δm is the difference between the mass of the zinc oxide arrester after being damp and the mass of the original zinc oxide arrester sample, m i is the mass of the i-th original zinc oxide arrester sample.

[0102] An alternating voltage is applied to the zinc oxide lightning arrester, and the zinc oxide lightning arrester is measured based on the FDS frequency domain dielectric spectrum tester to obtain the distributed frequency domain dielectric spectrum of the zinc oxide lightning arrester. The output voltage peak range is 0-200V; the capacitance test range is 10pF-100μF; the frequency is 1mHz-10kHz; the measurement error and dielectric loss measurement error are 1pF±0.5%.

[0103] In FDS measurement, an alternating voltage is applied to the zinc oxide arrester The corresponding current through the medium for:

[0104]

[0105] Among them, C′(ω) and C″(ω) represent the real and imaginary parts of the complex capacitance of the dielectric medium, respectively; C0, ε'(ω), ε”(ω) are the geometric capacitance and the real and imaginary parts of the complex relative permittivity of the dielectric medium, respectively; the ratio between ε”(ω) and ε'(ω) is the dielectric loss factor tanδ, and the real part of the complex relative permittivity ε'(ω) is the energy storage component. The imaginary part ε”(ω) is further expressed as:

[0106]

[0107] Among them, ε′ r ′(ω) is the dielectric relaxation component, is the conduction loss.

[0108] Under the action of the alternating electric field of the dielectric, when the frequency is low, free charges will accumulate around the electrode. This leads to a higher dielectric constant at lower frequencies; this phenomenon is called the electrode polarization effect. This high dielectric constant caused by electrode polarization interacts with dielectric relaxation. The dielectric modulus is the reciprocal of the complex relative dielectric constant and is defined as:

[0109]

[0110] Where M′(ω) and M″(ω) are the real and imaginary parts of the dielectric modulus, respectively, which can be further expressed as the complex relative permittivity:

[0111]

[0112] Among them, it can be seen from formula (5) and formula (6) that the dielectric modulus minimizes the change of the conductivity value at low frequency. Therefore, the influence of electrode polarization does not appear in the dielectric modulus spectrum, which is suitable for analyzing the dielectric relaxation process of zinc oxide lightning arresters. The dielectric relaxation process is analyzed using the Havriliak-Negami model function, which is:

[0113]

[0114] Among them, M s is the static dielectric modulus, M ∞ is the high frequency dielectric modulus, τ hn is the relaxation time constant, α is the shape parameter of the symmetric distribution of the relaxation mechanism, and β is the shape parameter of the asymmetric distribution of the relaxation mechanism.

[0115] The real part M′(ω) and imaginary part M″(ω) of the complex dielectric modulus can be expressed using the Havriliak-Negami (HN) relaxation parameters as

[0116]

[0117] in,

[0118]

[0119] The present invention calculates the frequency variation of the real part and the imaginary part of the complex relative dielectric constant, i.e., ε'(ω), ε"(ω), based on the geometric capacitance C0 of the zinc oxide lightning arrester. Specifically, the relationship between the real part and the imaginary part of the complex capacitance of the dielectric medium and the geometric capacitance and the complex relative dielectric constant of the dielectric medium is obtained through formula (2). That is, the modulus of the complex capacitance of the dielectric medium is extracted as the geometric capacitance, and the real part and the imaginary part are retained as the complex relative dielectric constant. Then, according to the analysis, formula (3) in the low-frequency state is simplified to obtain formula (10).

[0120] According to formula (3), at low frequency (1mHz), the conduction loss is inversely proportional to the frequency and is the main loss. Assuming that at low frequency, the loss caused by dielectric relaxation has negligible effect on the conduction loss, the conduction loss is estimated by modifying formula (3). At low frequency, formula (3) is written as formula (10):

[0121]

[0122] In the low frequency state, the DC conductivity σ0 is obtained by formula (10); given the DC conductivity σ0, The conduction loss in the high-frequency state is obtained, and then the loss caused by the dielectric relaxation phenomenon is calculated by formula (3). At lower frequencies, the loss caused by the dielectric relaxation phenomenon is mainly conduction loss. Taking this into account, the dielectric modulus characteristics, namely M′(ω) and M″(ω), are calculated using formulas (5) and (6) to reduce the influence of conduction loss at low frequencies. M′(ω) increases with the increase of the measurement frequency. The value of M″(ω) increases first and then decreases with the change of frequency, showing a peak shape. The peak value reached by M″(ω) with the change of frequency is called the "relaxation peak". The relaxation peak is an important parameter reflecting the loss of the dielectric polarization process. The size of the "relaxation peak" increases with the degree of moisture of the lightning arrester. This is because with the intrusion of moisture on the interface, the loss of the polarization process increases, and the "relaxation peak" increases. Therefore, the "relaxation peak" can be used as a suitable indicator for estimating the moisture content in MOSA. The relationship between the relaxation peak and the degree of moisture C% is as follows Figure 3 .

[0123] The Havriliak-Negami model is used for analysis

[0124] The fitted HN model parameters change with the moisture degree of zinc oxide arrester. Figure 4 , Figure 5 and Figure 6 As can be seen from the figure, the α value decreases with the increase of moisture content, while the β value increases with the increase of moisture content. hn The parameters are less affected by the moisture level of the zinc oxide arrester.

[0125] The relationship between the moisture degree C% of zinc oxide arrester and the HN model parameters α and β is fitted by function:

[0126] C(%)=k 00 +k 10 ×α+k 01 ×β+k 20 ×α 2 +k 02 ×β 2 (11)

[0127] Among them, k 00 is 12.39, k 10 is 1.11, k 01 is -29.58, k 20 is -6.87, k 02 It is 20.85.

[0128] A zinc oxide arrester sample was measured for moisture. First, the MOSA sample (for verification) was measured for FDS at 6 different moisture levels to obtain the frequency change of the complex capacitance, and the complex capacitance M′(ω) and M″(ω) were calculated using formula (2), formula (5) and formula (6). From the change of M″(ω), the relaxation peaks at 6 different moisture levels were obtained. Then, the water content of the inlet water was predicted using formula (11). The predicted values ​​and actual values ​​of the moisture level are shown in Table 1.

[0129] Table 1 Predicted and actual values ​​of moisture degree

[0130] Moisture degree C (%) Predicted moisture level C (%) 0.185 0.173 0.341 0.328 0.531 0.522 0.713 0.718 0.901 0.879 1.212 1.220

[0131] The root mean square error (RMSE) is used to measure the difference between the model prediction value and the actual value. The calculation formula is:

[0132]

[0133] Among them, y i is the actual value, is the predicted value, and n is the number of data points. Based on the given data, the square of the difference between each pair of predicted values ​​and the actual value is first calculated, and then the average of the squares of these differences is calculated, and finally the square root is taken to obtain the RMSE. The calculated RMSE value is 0.012922. It can be seen that the present invention predicts accurately.

[0134] The terminal device provided in an embodiment of the present invention. The terminal device of this embodiment includes: a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps in the above-mentioned method embodiments are implemented. Alternatively, when the processor executes the computer program, the functions of the modules / units in the above-mentioned device embodiments are implemented.

[0135] The computer program may be divided into one or more modules / units, and the one or more modules / units are stored in the memory and executed by the processor to accomplish the present invention.

[0136] The terminal device may be a computing device such as a desktop computer, a notebook, a PDA, a cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0137] The processor can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0138] The memory may be used to store the computer programs and / or modules, and the processor implements various functions of the terminal device by running or executing the computer programs and / or modules stored in the memory and calling the data stored in the memory.

[0139] If the module / unit integrated in the terminal device is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electric carrier signals and telecommunication signals.

[0140] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, a person skilled in the art should understand that the specific implementation modes of the present invention can still be modified or replaced by equivalents, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A method for evaluating the moisture level of a metal oxide surge arrester, characterized in that: include: The mass of the zinc oxide arrester after being dampened and the mass of the original zinc oxide arrester sample are collected to obtain the dampness degree of the zinc oxide arrester; Apply alternating voltage to the zinc oxide lightning arrester, measure the zinc oxide lightning arrester based on the FDS frequency domain dielectric spectrum tester, and obtain the distributed frequency domain dielectric spectrum of the zinc oxide lightning arrester; The distributed frequency-domain dielectric spectrum is analyzed to obtain the complex relative dielectric constant; Under the action of the alternating electric field of the medium, the dielectric modulus is obtained based on the complex relative dielectric constant; The dielectric modulus and complex relative permittivity were fitted based on the Havriliak-Negami model to obtain the relaxation peak curve. Based on the relationship between the moisture degree of zinc oxide arresters and the relaxation peak curve, the influence of the Havriliak-Negami model function on the moisture degree of zinc oxide arresters is obtained.

2. The method for evaluating the moisture degree of a metal oxide surge arrester according to claim 1, characterized in that: The method of obtaining the moisture degree of the zinc oxide arrester is specifically as follows: Among them, Δm is the difference between the mass of the zinc oxide arrester after being damp and the mass of the original zinc oxide arrester sample, m i is the mass of the i-th original zinc oxide arrester sample.

3. The method for evaluating the moisture degree of a metal oxide surge arrester according to claim 2, characterized in that: The distributed frequency domain dielectric spectrum is analyzed to obtain the complex relative dielectric constant, which is specifically: Apply alternating voltage to zinc oxide arrester The corresponding current through the medium for: Among them, C′(ω) and C″(ω) represent the real and imaginary parts of the complex capacitance of the dielectric medium, respectively; C0, ε′(ω), ε”(ω) are the geometric capacitance and the real and imaginary parts of the complex relative permittivity of the dielectric medium, respectively; the real part ε′(ω) of the complex relative permittivity is the energy storage component; the imaginary part ε”(ω) is further expressed as: Among them, ε′ r ′(ω) is the dielectric relaxation component, is the conduction loss.

4. The method for evaluating the moisture degree of a metal oxide surge arrester according to claim 3, characterized in that: The dielectric modulus is obtained based on the complex relative dielectric constant under the action of the dielectric alternating electric field. Specifically, when the frequency of the electric field is low, free charges will accumulate around the electrode, resulting in a higher dielectric constant at a lower frequency, resulting in an electrode polarization effect. The high dielectric constant caused by electrode polarization is mutually related to dielectric relaxation. The dielectric modulus is the inverse of the complex relative dielectric constant and is defined as: Among them, M′(ω) and M″(ω) are the real and imaginary parts of the dielectric modulus, respectively, which can be further expressed by the complex relative permittivity as follows: Among them, it can be seen from formula (4) and formula (5) that the dielectric modulus minimizes the change in conductivity value at low frequency.

5. The method for evaluating the moisture degree of a metal oxide surge arrester according to claim 4, characterized in that: The dielectric modulus is obtained based on the complex relative dielectric constant under the action of the dielectric alternating electric field, and further includes: in the low-frequency state, the influence of the loss caused by the dielectric relaxation phenomenon on the conduction loss is ignored, and the conduction loss is estimated by modifying formula (2). In the low-frequency state, formula (2) is written as formula (6): In the low frequency state, the DC conductivity σ0 is obtained by formula (6); given the DC conductivity σ0, The conduction loss in the high frequency state is obtained, and then the loss caused by dielectric relaxation is calculated using formula (2).

6. The method for evaluating the moisture degree of a metal oxide surge arrester according to claim 5, characterized in that: The dielectric modulus and the complex relative permittivity are fitted based on the Havriliak-Negami model to obtain a relaxation peak curve, specifically: the dielectric relaxation process is analyzed based on the Havriliak-Negami model function: Among them, M s is the static dielectric modulus, M ∞ is the high frequency dielectric modulus, τ hn is the relaxation time constant, α represents the shape parameter of the symmetrical distribution of the relaxation mechanism, and β represents the shape parameter of the asymmetrical distribution of the relaxation mechanism. M′(ω) increases with the increase of the measurement frequency. The value of M″(ω) first increases and then decreases with the change of frequency. The peak value reached by M″(ω) with the change of frequency is called the "relaxation peak".

7. The method for evaluating the moisture degree of a metal oxide surge arrester according to claim 6, characterized in that: The influence of the Havriliak-Negami model function on the moisture degree of the zinc oxide arrester is obtained as follows: C(%)=k 00 +k 10 ×α+k 01 ×β+k 20 ×α 2 +k 02 ×β 2 (8) Among them, k 00 , k 10 , k 01 , k 20 and k 02 are all constants.

8. A system for evaluating the moisture level of metal oxide surge arresters, characterized in that: include: A collection module, wherein the collection module collects the mass of the zinc oxide lightning arrester after being damp and the mass of the original zinc oxide lightning arrester sample to obtain the degree of dampness of the zinc oxide lightning arrester; A first acquisition module, wherein the first acquisition module applies an alternating voltage to the zinc oxide lightning arrester, measures the zinc oxide lightning arrester based on an FDS frequency domain dielectric spectrum tester, and acquires a distributed frequency domain dielectric spectrum of the zinc oxide lightning arrester; An analysis module, wherein the analysis module analyzes the distributed frequency domain dielectric spectrum to obtain a complex relative dielectric constant; A dielectric modulus acquisition module, wherein the dielectric modulus acquisition module obtains the dielectric modulus based on the complex relative dielectric constant under the action of the medium alternating electric field; A fitting module, wherein the fitting module fits the dielectric modulus and the complex relative permittivity based on the Havriliak-Negami model to obtain a relaxation peak curve; The second acquisition module obtains the influence of the Havriliak-Negami model function on the moisture degree of the zinc oxide arrester based on the relationship between the moisture degree of the zinc oxide arrester and the relaxation peak curve.

9. A terminal device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing a computer program, 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 7 are implemented.

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