A temperature measuring method and system for a temperature-sensitive lightning protection combined insulator

Abstract

This invention discloses a temperature measurement method and system for a temperature-sensing lightning protection combined insulator, belonging to the field of dielectric temperature measurement technology. It includes: real-time acquisition of temperature data at the insulation interface, processing the temperature data to obtain temperature rise data of the wet / polluted interface; acquisition of schlieren images of the discharge channel and extraction of deflection angle data, processing the deflection angle data to obtain the radial distribution of refractive index of the discharge channel; inversion of the radial distribution of refractive index to obtain gas temperature data of the discharge channel; and determination of the temperature evolution law of the wet / polluted interface and arc during the arc initiation to flashover formation process of the temperature-sensing lightning protection combined insulator under different pollution levels based on the temperature rise data of the wet / polluted interface and the gas temperature data of the discharge channel. This invention fundamentally solves the contradiction between the axisymmetric assumption and the actual asymmetric morphology, significantly improving the accuracy of discharge channel temperature measurement.

Description

Technical Field

[0001] This invention relates to the field of dielectric temperature measurement technology, and in particular to a temperature measurement method and system for a temperature-sensing lightning protection combined insulator. Background Technology

[0002] Lightning strikes severely impact the safe operation of power lines. 10kV distribution lines, lacking lightning protection wires, are highly susceptible to direct lightning strikes, leading to line tripping, conductor breakage, and equipment damage. In severe cases, falling wires can cause electric shock injuries and fatalities. Combined insulators, as an effective solution for line lightning protection, combine lightning protection, insulation, and support functions. They can simultaneously replace traditional line surge arresters and insulators, offering advantages such as cost-effectiveness and convenient installation and maintenance, and have broad application prospects.

[0003] The wet-contamination interface temperature and discharge channel temperature in composite insulators are key parameters for revealing the arc development mechanism. Existing wet-contamination interface temperature measurement schemes mostly employ infrared thermometry. This method involves deploying an infrared thermal imager aimed at the wet-contamination interface region, capturing the infrared radiation emitted by the interface itself and converting it into an electrical signal. After signal calibration, a temperature distribution image is generated, allowing for a direct visual acquisition of the wet-contamination interface temperature. Existing discharge channel temperature measurement schemes mostly employ the traditional schlieren method. This method involves constructing a schlieren system including a light source, collimating lens, schlieren knife edge, imaging lens, and camera. The light emitted by the light source is processed into parallel light by the collimating lens. When it passes through the discharge channel region, the gas density fluctuations caused by temperature changes within the channel deflect the light. The deflected light is then blocked by the schlieren knife edge, projected by the imaging lens, and collected by the camera. The temperature field distribution of the discharge channel is inverted through the contrast of the image's brightness.

[0004] The traditional schlieren method involves reconstructing the temperature field distribution of a discharge channel by analyzing the contrast between light and dark areas of an image. This process includes: using a knife-cut to cut a parallel beam of light disturbed by the discharge region, converting the refractive index gradient into image grayscale contrast; extracting a two-dimensional deflection angle field based on the linear relationship between image grayscale and light deflection angle; using the line integral of the refractive index gradient corresponding to the deflection angle along the light path, and inverting the spatial distribution of the refractive index using Abelian transform; and calculating the temperature field point by point based on the spatial distribution of the refractive index and the state equation, thus achieving quantitative reconstruction from a two-dimensional light-dark distribution to a three-dimensional temperature field.

[0005] The inversion method in the traditional schlieren method relies heavily on the axisymmetric assumption of the discharge channel when reconstructing the refractive index field using the Abelian transform. However, the actual discharge channel often exhibits asymmetric and dynamically changing spatial distribution characteristics, which leads to a large error in the reconstructed refractive index distribution and reduces the accuracy of the discharge channel temperature measurement in the composite insulator. Summary of the Invention

[0006] Therefore, it is necessary to provide a temperature measurement method and system for temperature-sensing lightning protection combined insulators to address the aforementioned technical problems.

[0007] This invention provides a method for measuring the temperature of a temperature-sensing lightning protection combined insulator. Miniature temperature sensor chips are embedded in multiple insulation interfaces inside the temperature-sensing lightning protection combined insulator to obtain a miniature temperature measuring chip array; and a calibrated schlieren temperature measuring system is set on both sides of the discharge channel of the temperature-sensing lightning protection combined insulator. Temperature measurement methods include: Temperature data of the insulation interface is collected in real time by a micro temperature sensing chip array, and the temperature data of the insulation interface is processed by Fourier algorithm to determine the temperature distribution characteristics of the wet and dirty interface and obtain the temperature rise data of the wet and dirty interface. Schlieren images of the discharge channel were acquired using a calibrated schlieren thermometry system, and deflection angle data were extracted from these images using Abelian integration. An improved Gauss-Legendal algorithm was used to process the deflection angle data to reconstruct the spatial distribution of the refractive index of the discharge channel, yielding its radial refractive index distribution. The radial refractive index distribution of the discharge channel was then inverted using a plasma composition model to capture the quantitative relationship between the gas temperature data and the refractive index difference of the gas particles, thus obtaining the gas temperature data of the discharge channel. The improved Gauss-Legendal algorithm was obtained by dynamically adjusting the integration step size and introducing a weighting function adapted to the refractive index distribution, based on the Gauss-Legendal algorithm. Based on the temperature rise data of the wet pollution interface and the gas temperature data of the discharge channel, the evolution law of the wet pollution interface and arc temperature during the arc initiation to flashover formation process of the temperature-sensing lightning protection combined insulator under different pollution levels was determined.

[0008] Optionally, the schlieren image of the discharge channel is acquired through a calibrated schlieren thermography system, specifically including: The calibrated schlieren temperature measurement system includes: an LED light source, a main lens, two cemented lenses, a filter, a blade, and an image acquisition device; Among them, the spherical light emitted by the LED light source is integrated by the main lens and two cemented lenses into a parallel probe light that is perpendicularly incident on the discharge channel of the temperature-sensing lightning protection combined insulator, thus obtaining a parallel probe light carrying the refractive index gradient information of the discharge channel. Stray light from the parallel probe light is filtered out by a filter, and partial occlusion is achieved by a knife edge to create schlieren contrast. Finally, the image is imaged onto an image acquisition device to obtain a schlieren image of the discharge channel.

[0009] Optionally, the correction for changes in light intensity at the knife edge in the schlieren thermography system includes: The discharge channel causes an exponential attenuation of the intensity of the parallel probe light, and the intensity change at the knife edge caused by the deflection of the parallel probe light after passing through the discharge channel is determined based on the following formula: ; in, This represents the change in light intensity. α The deflection angle of the parallel probe light. f 2 represents the focal length of the cemented lens; The intensity relationship between spherical light and parallel probe light is determined based on the following formula: : in, β The attenuation coefficient is... d The thickness of the discharge channel. I 0 represents the luminous intensity of spherical light. I The intensity of the parallel probe light.

[0010] Optionally, deflection angle data can be extracted from the schlieren image of the discharge channel using Abelian integration based on the following formula: ; in, R Let be the boundary radius of the discharge channel. r Radial distance; An improved Gauss-Legend algorithm is used to process the deflection angle data to reconstruct the spatial distribution of the refractive index of the discharge channel, obtaining the radial distribution of the refractive index of the discharge channel, specifically including: The inverse Abelian transform equation is determined by Abelian integral based on the following formula: ; in, γ ( r ( ) represents the radial distribution of refractive index. γ 0 represents the background refractive index of the measured space. α ( x () represents the deflection angle data; The integration interval of the inverse Abelian transform equation is split into smaller parts, and the integration step size is dynamically adjusted adaptively according to the gradient change of the deflection angle data. A weighting function adapted to the refractive index distribution is introduced to suppress numerical calculation errors at singularities, thus obtaining the inverse deflection angle data. Through an iterative optimization process, the residual between the reversed deflection angle data and the deflection angle data is made to meet the preset threshold condition, thereby obtaining the radial refractive index of the discharge channel.

[0011] Optionally, the radial distribution of the refractive index of the discharge channel is inverted using a plasma composition model to capture the quantitative relationship between the gas temperature data of the discharge channel and the refractive index difference of the gas particles, thereby obtaining the gas temperature data of the discharge channel, specifically including: Based on the following formula, the corresponding particle number density and gas temperature data are determined according to the spatial distribution of the refractive index of the discharge channel obtained by the calibrated schlieren thermography system: ; ; ; ; in, n AB As molecules, n A and n B The number density of the molecular dissociation products. m AB The mass of molecule AB, m A and m B Let A and B be the masses. Let be the partition function of molecule AB. Z A and Z B Let be the partition function of atoms A and B. E LAB The energy required for the dissociation of molecules AB. k Boltzmann's constant, T e For electron temperature, The number density of unionized positive particles. n i The number density of unionized particles. For the positive partition function of the plasma, Z i For the plasma partition function, E di It is ionization energy. n e The total electron number density in the plasma. n i +j The positive dissociation density in the plasma. j is the charge coefficient of a positive ion. P For gas pressure, N The total number of particles in the gas. V Let be the volume of the gas. R con This is the universal gas constant. N A Let Avogadro's constant be 1. T gas For gas temperature, n zong The total particle number density in the plasma. n s In order to be with the first s Related to elements lThe particle number density of each component n p In order to be with the first p Related to elements m The particle number density of each component C These are the stoichiometric constants of the elements; Based on the following equation, the radial distribution of the refractive index of the discharge channel is inverted using a plasma composition model to obtain the gas temperature data of the discharge channel: ; in, where is the refractive index and e is the electron. a For atoms, m As molecules, i These are ions, where O represents oxygen atoms and N represents nitrogen atoms. L os For the Loschmidt number, λ The incident light wavelength, n For particle number density, A , B and χ is a relevant constant.

[0012] Optionally, based on the temperature rise data of the wet-contaminated interface and the gas temperature data of the discharge channel, the evolution law of the wet-contaminated interface and arc temperature during the arc initiation to flashover formation process of the temperature-sensing lightning protection combined insulator under different pollution levels is determined, specifically including: The temperature rise data of the wet interface was aligned with the schlieren image of the discharge channel along the time axis. Based on the characteristics of arc development, the discharge process of the discharge channel was divided into the arc initiation stage, the arc development stage, and the flashover formation stage. According to the set range of equivalent salt density, the wet contamination interface is divided into lightly contaminated, moderately contaminated, and heavily contaminated groups. The temperature rise rate, temperature peak and heat accumulation of the wet contamination interface, as well as the temperature peak and temperature spatial distribution characteristics of the discharge channel, are extracted for each discharge stage under each contamination level. Based on the time delay relationship between the temperature rise of the wet interface and the temperature of the discharge channel under each level of pollution, the trend of the temperature ratio change, and the coupling coefficient between the temperature rise rate of the wet interface and the temperature rise rate of the arc channel, the initial temperature of the wet interface at the moment of arc initiation and the spatial relative position of the high temperature zone of the arc channel and the high temperature zone of the wet interface are extracted. Based on the synchronicity or lag of the evolution of wet interface temperature and discharge channel temperature with the discharge stage under different pollution levels, the influence of wet interface heat accumulation on the temperature rise of the arc channel is analyzed, so as to summarize the coupling mode between wet interface temperature and discharge channel temperature from the arc initiation stage to the flashover formation process and obtain the evolution law.

[0013] This invention provides a temperature measurement system for a temperature-sensing lightning protection combined insulator, comprising: The insulation interface measurement module is used to collect temperature data of the insulation interface in real time through a micro temperature sensing chip array, and process the temperature data of the insulation interface through Fourier algorithm to determine the temperature distribution characteristics of the wet and dirty interface and obtain the temperature rise data of the wet and dirty interface. The discharge channel measurement module is used to acquire schlieren images of the discharge channel through a calibrated schlieren thermometry system, and extract deflection angle data from the schlieren images of the discharge channel through Abelian integration. An improved Gauss-Legend algorithm is used to process the deflection angle data to reconstruct the spatial distribution of the refractive index of the discharge channel, obtaining the radial distribution of the refractive index of the discharge channel. The radial distribution of the refractive index of the discharge channel is inverted using a plasma composition model to capture the quantitative relationship between the gas temperature data of the discharge channel and the refractive index difference of gas particles, obtaining the gas temperature data of the discharge channel. The improved Gauss-Legend algorithm is obtained by dynamically adjusting the integration step size and introducing a weighting function adapted to the refractive index distribution based on the Gauss-Legend algorithm. The temperature measurement module is used to determine the evolution of the temperature of the wet and polluted interface and the arc during the arc initiation to flashover formation process of the temperature-sensing lightning protection combined insulator under different pollution levels, based on the temperature rise data of the wet and polluted interface and the gas temperature data of the discharge channel.

[0014] The temperature measurement method and system for a temperature-sensing lightning protection combined insulator provided in this invention have the following advantages compared with the prior art: This invention adaptively matches the local asymmetric structure and dynamic evolution characteristics of the discharge channel by dynamically adjusting the integration step size. Simultaneously, it introduces a weighting function that adapts to the refractive index distribution to enhance the fitting ability to non-uniform distributions in the actual refractive index. This improved Gauss-Legend algorithm exhibits stronger reconstruction accuracy when dealing with asymmetric fields and non-uniform refractive index distributions. It can accurately reconstruct the refractive index spatial distribution of the temperature-sensing lightning protection combined insulator without pre-setting axisymmetric conditions, fundamentally resolving the contradiction between the axisymmetric assumption and the actual asymmetric shape, and significantly improving the accuracy of discharge channel temperature measurement. Attached Figure Description

[0015] Figure 1 A schematic diagram of an existing combined insulator for a temperature measurement method of a temperature-sensing lightning protection combined insulator provided in one embodiment; Figure 2 This is a flowchart illustrating a temperature measurement method for a temperature-sensing lightning protection combined insulator provided in one embodiment; Figure 3 This is a schematic diagram of a temperature-sensing lightning protection combined insulator, provided in one embodiment, for a temperature measurement method. Figure 3 (a) in the diagram is a three-dimensional schematic. Figure 3 (b) in the diagram is a cross-sectional view; Figure 4 This is a schematic diagram of the schlieren system optical path for a temperature measurement method of a temperature-sensing lightning protection combined insulator provided in one embodiment.

[0016] Figure 3 In the figure, 1. First metal electrode; 2. Second metal electrode; 3. First silicone rubber skirt; 4. Second silicone rubber skirt; 5. Zinc oxide valve plate; 6. Insulating core rod. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0018] Temperature measurement scheme for wet and dirty interface: (1) Deploy an infrared thermal imager to target the wet and dirty interface area, capture the infrared radiation emitted by the interface itself and convert it into an electrical signal. After signal calibration, generate a temperature distribution image. This can directly obtain the temperature of the dirt layer. However, the high-temperature infrared radiation generated by the local electric arc will mix with the interface signal, seriously interfering with the measurement accuracy and making it impossible to distinguish the temperature signal of the electric arc and the wet and dirty interface. (2) Fiber grating sensing method: By implanting a fiber grating sensor at the target measurement point of the insulating wet and dirty interface, a specific wavelength of detection light is input into the fiber. After the detection light is reflected by the grating, the temperature of the measurement point is calculated based on the correspondence between its Bragg wavelength offset and temperature. Although it can avoid the interference of electric arc, the fiber has inherent defects such as temperature drift and easy breakage. The long-term operation reliability is insufficient and passive wireless measurement cannot be realized.

[0019] Discharge channel temperature measurement schemes: (1) Optical radiation method (including spectral method): Spectrometers, photodetectors and other optical detection equipment are arranged to be aligned with the discharge channel area to collect the optical radiation signal during the discharge process. The discharge channel temperature is inverted by combining the radiation characteristics of plasma particles. This technology is mature but depends on the intensity of radiation light and the distribution of plasma particles. The measurement accuracy is limited in low light intensity and small size discharge scenarios such as corona and streamers. (2) Traditional schlieren method: A schlieren system including a light source, collimating mirror, schlieren blade, imaging lens and camera is built. The light emitted by the light source is processed into parallel light by the collimating mirror. When it passes through the discharge channel area, the gas density fluctuation caused by the temperature change in the channel will cause the light to be deflected. The deflected light is blocked by the schlieren blade and projected by the imaging lens and then collected by the camera. The temperature field distribution of the discharge channel is inverted by the contrast of the brightness and darkness of the image. This method has strong adjustability and spatial resolution. It is more advantageous when measuring the temperature field of small discharge channels such as corona and streamers. It is suitable for measuring the temperature field evolution of key positions such as the arc foot during the local arc development process. However, this method requires the use of the gas constant method to invert temperature. When the changes in parameters such as the molar mass M, Gladstone-Dale constant K_G, and pressure P of the discharge channel are not negligible relative to the change in the gas refractive index difference γ-1, it will be impossible to calculate the gas temperature data of the discharge channel, thus limiting its applicability.

[0020] However, the polluted environment seriously affects the reliability of the composite insulator: on the one hand, the arc at the wet pollution interface is prone to unexpected changes under overvoltage, leading to the burning and deterioration of the silicone rubber sheath; on the other hand, creepage or even flashover tripping accidents are prone to occur under the operating voltage in heavily polluted areas. The root cause is that the discharge arc path of the composite insulator is complex and the multi-field coupling mechanism of electrothermal flow is unclear, and the control of the insulation structure lacks theoretical basis.

[0021] This invention provides a method for measuring the temperature of a temperature-sensing lightning protection combined insulator, aiming to reveal the evolution law between the wet and polluted interface and the arc temperature. The method combines experimental research with numerical calculation. Miniature temperature sensor chips are embedded in multiple insulation interfaces inside the temperature-sensing lightning protection combined insulator, forming a miniature temperature measurement chip array; and a calibrated schlieren temperature measurement system is set on both sides of the discharge channel of the temperature-sensing lightning protection combined insulator.

[0022] like Figure 2 As shown, the temperature measurement methods include: Temperature data of the insulation interface is collected in real time by a miniature temperature sensing chip array, and the temperature data of the insulation interface is processed by Fourier algorithm to determine the temperature distribution characteristics of the wet and dirty interface and obtain the temperature rise data of the wet and dirty interface.

[0023] Schlieren images of the discharge channel were acquired using a calibrated schlieren thermography system, and deflection angle data were extracted from these images via Abelian integration. An improved Gauss-Legendal algorithm was used to process the deflection angle data to reconstruct the spatial distribution of the refractive index of the discharge channel, yielding its radial refractive index distribution. The radial refractive index distribution of the discharge channel was then inverted using a plasma composition model to capture the quantitative relationship between the gas temperature data and the refractive index difference of gas particles, thus obtaining the gas temperature data of the discharge channel. The improved Gauss-Legendal algorithm was developed by dynamically adjusting the integration step size and introducing a weighting function adapted to the refractive index distribution, based on the Gauss-Legendal algorithm.

[0024] Based on the temperature rise data of the wet pollution interface and the gas temperature data of the discharge channel, the evolution law of the wet pollution interface and arc temperature during the arc initiation to flashover formation process of the temperature-sensing lightning protection combined insulator under different pollution levels was determined.

[0025] Specifically, the deflection angle data is extracted from the schlieren image of the discharge channel using the following formula through Abelian integration: ; in, R Let be the boundary radius of the discharge channel. r This represents the radial distance.

[0026] An improved Gauss-Legend algorithm is used to process the deflection angle data to reconstruct the spatial distribution of the refractive index of the discharge channel, obtaining the radial distribution of the refractive index of the discharge channel, specifically including: The inverse Abelian transform equation is determined by Abelian integral based on the following formula: ; in, γ ( r ( ) represents the radial distribution of refractive index. γ 0 represents the background refractive index of the measured space. α ( x () represents the deflection angle data; The integration interval of the inverse Abelian transform equation is split, and the integration step size is dynamically adjusted adaptively according to the gradient change of the deflection angle data. A weighting function adapted to the refractive index distribution is introduced to suppress numerical calculation errors at singularities, thus obtaining the inverse deflection angle data. Through an iterative optimization process, the residual between the inverse deflection angle data and the deflection angle data is made to meet a preset threshold condition, thereby obtaining the radial refractive index distribution of the discharge channel.

[0027] Based on the temperature rise data of the wet pollution interface and the gas temperature data of the discharge channel, the evolution law of the wet pollution interface and arc temperature during the arc initiation to flashover formation process of the temperature-sensing lightning protection combined insulator under different pollution levels was determined, specifically including: The temperature rise data of the wet interface was aligned with the schlieren image of the discharge channel along the time axis. Based on the characteristics of arc development, the discharge process of the discharge channel was divided into the arc initiation stage, the arc development stage, and the flashover formation stage.

[0028] Based on the set range of equivalent salt density, the wet fouling interface was divided into a lightly fouled group, a moderately fouled group, and a heavily fouled group. The temperature rise rate, peak temperature, and heat accumulation of the wet fouling interface, as well as the peak temperature and spatial temperature distribution characteristics of the discharge channel, were extracted for each discharge stage under each fouling level.

[0029] Based on the time delay relationship between the temperature rise of the wet interface and the temperature of the discharge channel under each level of contamination, the trend of the temperature ratio change, and the coupling coefficient between the temperature rise rate of the wet interface and the temperature rise rate of the arc channel, the initial temperature of the wet interface at the moment of arc initiation and the spatial relative positions of the high-temperature zone of the arc channel and the high-temperature zone of the wet interface are extracted.

[0030] Based on the synchronicity or lag of the evolution of wet interface temperature and discharge channel temperature with the discharge stage under different pollution levels, the influence of wet interface heat accumulation on the temperature rise of the arc channel is analyzed, so as to summarize the coupling mode between wet interface temperature and discharge channel temperature from the arc initiation stage to the flashover formation stage and obtain the evolution law.

[0031] A specific embodiment of the present invention is provided: 1. Temperature measurement experiment of "heterogeneous medium" based on surface acoustic wave and schlieren system.

[0032] like Figure 1 As shown, existing combined insulators consist of composite insulation with parallel gaps connected in series with a surge arrester. The combined insulator of this invention is based on passive wireless surface acoustic wave temperature measurement technology. A miniature temperature sensor chip is embedded inside the insulation interface (the interface between the insulator surface and the gas, with the sensor built into the insulator skirt sheath). The chip size is precisely designed to be 5×5mm. To meet the requirements of temperature signal transmission, the outer diameter of the loop antenna used for signal transmission is adapted to the diameter of the insulator itself, ultimately developing an autonomous temperature-sensing surge protection combined insulator suitable for wet and polluted interfaces. The structure of this surge protection insulator is as follows... Figure 3 As shown, the definitions of each key component are as follows: 1 is the first metal electrode, 2 is the second metal electrode, 3 is the first silicone rubber skirt, 4 is the second silicone rubber skirt, 5 is the zinc oxide valve plate, and 6 is an insulating core rod with dual properties of acid resistance and high temperature resistance.

[0033] While ensuring that the external insulation strength of the insulator is not affected, a temperature-sensing chip array integrated inside the insulator can be used to achieve real-time monitoring of the temperature rise at the wet-contamination interface during the insulator's withstand voltage process and the development of local electric arcs. This technical solution effectively overcomes the technical challenge of inaccurate measurements caused by high-temperature interference from local electric arcs when measuring the temperature of the wet-contamination interface using conventional infrared thermometry.

[0034] To address the characteristics of rapid localized arc development and irregular spatial morphology, a rectified schlieren temperature measurement system was constructed, based on a high-stability LED light source, a main lens, two cemented lenses, a filter, a knife edge, and an image acquisition device (ultra-high-speed camera). A temperature-sensing lightning protection insulator was placed between the two cemented lenses, with the discharge channel located on the surface of the insulator. This system enables visual capture of the arc discharge process and acquisition of temperature-related signals. The layout and optical path diagram of the rectified schlieren temperature measurement system are shown below. Figure 4 As shown.

[0035] In this process, the spherical light emitted by the LED light source is integrated by the main lens and two cemented lenses to form a parallel probe light that is perpendicularly incident on the discharge channel of the temperature-sensing lightning protection combined insulator, resulting in a parallel probe light carrying information about the refractive index gradient of the discharge channel. Stray light from the parallel probe light is filtered out by a filter, and partial obstruction is achieved by a knife edge to form a schlieren contrast. Finally, the image is imaged on an image acquisition device to obtain a schlieren image of the discharge channel.

[0036] Assuming the light intensities of the spherical light and the parallel probe light are respectively I 0 and I According to the Lambert-Beer law, the relationship between the two is as follows: (1); In the formula, β The attenuation coefficient is... d Let be the thickness of the discharge channel. The change in light intensity at the knife edge consists of two parts: A. The discharge channel causes an exponential attenuation of the emitted light intensity. B. The parallel probe light is deflected after passing through the discharge channel with a refractive index of n, thus causing a change in the light intensity (grayscale) at the knife edge. The grayscale change caused by the deflection of the probe light is as follows: (2); In the formula, This represents the change in light intensity. α The deflection angle of the parallel probe light. f 2 represents the focal length of the cemented lens.

[0037] Under atmospheric pressure testing conditions, the discharge channel exhibits a rarefied plasma state with low particle density and a low light attenuation coefficient. β Negligible, and the thickness of the discharge channel is also negligible. dThe optical path length is much shorter than that of a schlieren system, and can be approximated as the output light. I = I 0, therefore, the grayscale change (light intensity change) of the discharge channel measured by the schlieren system will all come from the light deflection angle. α The corresponding change in optical offset can be detected by the displacement of the blade. Equivalent light deflection angle α The resulting optical shift can then be used to calculate the optical deflection angle. α .

[0038] 2. Arc temperature inversion algorithm based on plasma composition model.

[0039] Extract from the schlieren image r One row in the direction yields discrete scatter points of deflection angle data. α These deflection scattering points are probes of the light rays along the discharge channel. x Line integral in the axial direction. Assuming the discharge channel is distributed in a space with axisymmetric properties, the Abelian integral is used to describe the correspondence between the deflection angle data points and the refractive index, as shown in equation (3): (3); In the formula, R Represents the boundary radius of the discharge channel; r Represents radial distance. x Let be the independent variable; the inverse Abel transform equation corresponding to equation (3) is: (4); In the formula, γ 0 is the background refractive index of the measured space. γ ( r () is the radial distribution of refractive index. α ( x ) is the measured deflection angle data. The radial coordinate of the discharge channel in equation (4) is... r Each integration point is a singularity, and numerical calculation methods must be used to solve equation (4).

[0040] To address the solution of equation (4), an improved Gauss-Legendal algorithm is proposed to reconstruct the refractive index of the discharge channel in the schlieren image. γFirst, discrete deflection angle data are extracted from schlieren images. The integration interval is split to avoid singularities, and the integration step size is dynamically adjusted according to the deflection angle gradient. Simultaneously, a weighting function adapted to the refractive index distribution is introduced to enhance the calculation accuracy near singularities. Through iterative optimization, the residual between the inferred deflection angle and the measured value is brought to a satisfactory level, ultimately yielding the accurate refractive index. The plasma composition model is based on the assumption of local thermodynamic equilibrium, considering the first-order ionized components of air. A closed nonlinear equation system is constructed using the law of mass action and quasi-neutrality. An improved quasi-Newton iterative algorithm is used to optimize the Jacobian matrix update and step size selection, rapidly solving for the number density of each particle. Then, the refractive index difference of each component is summarized according to the superposition law, and the discharge channel temperature is inverted by combining its quantitative relationship with temperature.

[0041] The project considers the first-order ionization of molecules and atoms, uses a simplified ratio method to calculate the partition function, and establishes a plasma composition model based on the local thermodynamic equilibrium (LTE) theory. The plasma composition model is a set of closed nonlinear equations consisting of the law of mass action, plasma quasi-neutrality, the law of partial pressure of gases, and the conservation of stoichiometry. This set of equations can be solved by an improved quasi-Newton iterative algorithm. Among them, the total refractive index difference of the discharge channel is the sum of the refractive index differences of electrons, atoms, molecules, and ions, which obeys the superposition law and can be calculated by equation (5): (5); In the formula, For refractive index, subscript e, a , m , i O and N represent electron, atom, molecule, ion, oxygen atom, and nitrogen atom, respectively. L os , λ , n These represent the Loschmidt constant, the incident light wavelength, and the particle number density, respectively. A , B , χ Represents the relevant constants. The refractive index difference of electrons, atoms, molecules, and ions depends on the number density of each particle, and the number density of each particle has a quantitative relationship with the gas temperature data, as shown in equations (6) to (9). Therefore, the refractive index of the discharge channel is measured by the schlieren system. γ By substituting the values ​​into the equation, the total refractive index difference can be calculated, and the corresponding particle number density and gas temperature data can be obtained.

[0042] (6); In the formula, where, n AB As molecules, n A andn B The number density of the molecular dissociation products. m AB The mass of molecule AB, m A and m B Let A and B be the masses. Let be the partition function of molecule AB. Z A and Z B Let be the partition function of atoms A and B. E LAB The energy required for the dissociation of molecules AB. k Boltzmann's constant, T e For electron temperature, The number density of unionized positive particles. n i The number density of unionized particles. For the positive partition function of the plasma, Z i For the plasma partition function, E di The value of ionization energy is calculated using a simplified ratio method.

[0043] (7) In the formula, n e m represents the total electron number density in the plasma. -3 ; n i +j m represents the positive ion density in the plasma. -3 ; j It is the charge coefficient of a positive ion; when the charge is 1... j =1.

[0044] (8) In the formula, P For gas pressure, N The total number of particles in the gas. V Let be the volume of the gas. R con It is the universal gas constant, J / (mol·K); N A It is Avogadro's constant, mol -1 ; k It is the Boltzmann constant, J / K; n zong It is the total number density of particles in the plasma, m-3 ; T gas For gas temperature, n zong The total particle number density in the plasma.

[0045] (9) In the formula, n s Indicates the relationship with the first s Related to elements l The particle number density of each component, m -3 ; n p Indicates the relationship with the first p Related to elements m The particle number density of each component, m -3 ; C This is the stoichiometric constant of the elements, with a value of 3.728 (nitrogen accounts for 78.084% / oxygen accounts for 20.946%). When the plasma is in local thermodynamic equilibrium, it has... T gas = T e By combining equations (6) to (9), the relationship between the number density of various particles and the gas temperature data can be calculated.

[0046] 3. The evolution of the wet and dirty interface and the arc temperature.

[0047] AC flashover tests on lightning protection combined insulators were conducted using the constant voltage rise and fall method. The equivalent salt density (ESDD) was set to 0.01 mg / cm²-0.25 mg / cm², covering three typical pollution levels: light (0.01-0.05 mg / cm²), moderate (0.05-0.15 mg / cm²), and heavy (0.15-0.25 mg / cm²), which closely matches the actual operating environment of power grid insulators.

[0048] Temperature rise data of the insulation interface was collected by a surface acoustic wave sensor array. The temperature of the insulation interface and the wet contamination interface was quantitatively characterized using a Fourier algorithm, thus obtaining the temperature rise data of the wet contamination interface. Schlieren images of the discharge channel were acquired using a high-speed camera, and the discharge channel temperature data was obtained by inversion using a plasma model. Finally, the evolution of the temperature of the wet contamination interface and the arc during the arc initiation to flashover formation under different pollution levels was investigated. "Heterogeneous media" refers to the wet contamination interface and the arc; the temperature difference between the two is large and cannot be measured by a single method. By acquiring data separately using a coupled thermometry method, the correlation between their temperature evolution under different pollution levels can be analyzed.

[0049] 4. Effect description.

[0050] (1) Significantly improved temperature measurement accuracy: The heterogeneous medium coupling temperature measurement method solves the problem that traditional technology cannot simultaneously and accurately measure the temperature of wet and dirty interface and discharge channel. The SAW sensor avoids arc interference, and the improved schlieren method inversion error is controlled within an acceptable range. The temperature measurement range covers 100~10K, providing reliable data support for mechanism research.

[0051] (2) Mechanism research support: The temperature evolution law of different pollution levels and different arc stages was clarified, the complete arc development thermal field parameters were obtained, and the temperature evolution law of wet pollution interface and arc was clarified.

[0052] (3) A passive wireless miniature surface acoustic wave temperature sensor is used to monitor the temperature of the insulation interface and the wet and polluted interface of the composite insulator by taking advantage of its technical advantages of no power supply dependence, strong electromagnetic interference resistance and wet and polluted corrosion resistance. The temperature rise rate, temperature distribution gradient and heat accumulation law of the wet and polluted interface during the arc development process are analyzed in detail to reveal the intrinsic relationship between interface thermal stress and insulation failure in wet and polluted environment.

[0053] (4) Coupled with the plasma component model, the temperature change characteristics of the dynamic arc are systematically studied, and the temperature evolution law of the wet and polluted interface and the arc during the multi-arc development process of the lightning protection combined insulator is further explored. At the same time, the number density distribution law of various particles such as electrons, positive and negative ions, atoms and molecules generated by gas discharge is revealed, and the limitations of the gas constant method in temperature inversion when the changes in pressure, molar mass and Gladstone-Dale constant of the discharge channel cannot be ignored relative to the change in gas refractive index difference are solved.

[0054] Based on the same inventive concept, embodiments of the present invention provide a temperature measurement system for a temperature-sensing lightning protection combined insulator, the system comprising: The insulation interface measurement module is used to collect temperature data of the insulation interface in real time through a micro temperature sensing chip array, and process the temperature data of the insulation interface through Fourier algorithm to determine the temperature distribution characteristics of the wet and dirty interface and obtain the temperature rise data of the wet and dirty interface.

[0055] The discharge channel measurement module is used to acquire schlieren images of the discharge channel through a calibrated schlieren thermometry system and extract deflection angle data from the schlieren images using Abelian integration. An improved Gauss-Legendal algorithm is used to process the deflection angle data to reconstruct the spatial distribution of the refractive index of the discharge channel, obtaining the radial distribution of the refractive index. The radial distribution of the refractive index of the discharge channel is then inverted using a plasma composition model to capture the quantitative relationship between the gas temperature data and the refractive index difference of gas particles, obtaining the gas temperature data of the discharge channel. The improved Gauss-Legendal algorithm is obtained by dynamically adjusting the integration step size and introducing a weighting function adapted to the refractive index distribution based on the Gauss-Legendal algorithm.

[0056] The temperature measurement module is used to determine the evolution of the temperature of the wet and polluted interface and the arc during the arc initiation to flashover formation process of the temperature-sensing lightning protection combined insulator under different pollution levels, based on the temperature rise data of the wet and polluted interface and the gas temperature data of the discharge channel.

[0057] The embodiments described above are merely examples of 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 invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for measuring the temperature of a temperature-sensing lightning protection combined insulator, characterized in that, Miniature temperature sensor chips are embedded in multiple insulation interfaces inside the temperature-sensing lightning protection combined insulator to obtain a miniature temperature measuring chip array. A correction schlieren temperature measurement system is installed on both sides of the discharge channel of the temperature-sensing lightning protection combined insulator. The temperature measurement method includes: Temperature data of the insulation interface is collected in real time by a micro temperature sensing chip array, and the temperature data of the insulation interface is processed by Fourier algorithm to determine the temperature distribution characteristics of the wet and dirty interface and obtain the temperature rise data of the wet and dirty interface. Schlieren images of the discharge channel are acquired using a calibrated schlieren thermography system, and deflection angle data is extracted from these images using Abelian integration. An improved Gauss-Legendal algorithm is used to process the deflection angle data to reconstruct the spatial distribution of the refractive index of the discharge channel, yielding its radial refractive index distribution. The radial refractive index distribution of the discharge channel is then inverted using a plasma composition model to capture the quantitative relationship between the gas temperature data and the refractive index difference of the gas particles, thus obtaining the gas temperature data of the discharge channel. The improved Gauss-Legendal algorithm is obtained by dynamically adjusting the integration step size and introducing a weighting function adapted to the refractive index distribution, based on the Gauss-Legendal algorithm. Based on the temperature rise data of the wet pollution interface and the gas temperature data of the discharge channel, the evolution law of the wet pollution interface and arc temperature during the arc initiation to flashover formation process of the temperature-sensing lightning protection combined insulator under different pollution levels was determined.

2. The temperature measurement method for a temperature-sensing lightning protection combined insulator as described in claim 1, characterized in that, The acquisition of schlieren images of the discharge channel through the calibrated schlieren thermometry system specifically includes: The corrected schlieren temperature measurement system includes: an LED light source, a main lens, two cemented lenses, a filter, a blade, and an image acquisition device; The spherical light emitted by the LED light source is integrated by the main lens and the two cemented lenses into a parallel probe light that is perpendicularly incident on the discharge channel of the temperature-sensing lightning protection combined insulator, thereby obtaining a parallel probe light carrying the refractive index gradient information of the discharge channel. The stray light of the parallel probe light is filtered out by the filter, and the blade partially blocks the light to form a schlieren contrast. Finally, the image is imaged on the image acquisition device to obtain a schlieren image of the discharge channel.

3. The temperature measurement method for a temperature-sensing lightning protection combined insulator as described in claim 2, characterized in that, The changes in light intensity at the blade edge in the corrected schlieren thermometry system include: The discharge channel causes an exponential attenuation of the intensity of the parallel probe light, and the intensity change at the blade edge caused by the deflection of the parallel probe light after passing through the discharge channel is determined based on the following formula: ； in, This represents the change in light intensity. α The deflection angle of the parallel probe light. f 2 represents the focal length of the cemented lens; The intensity relationship between the spherical light and the parallel probe light is determined based on the following formula: ： in, β The attenuation coefficient is... d The thickness of the discharge channel. I 0 represents the luminous intensity of spherical light. I The intensity of the parallel probe light.

4. The temperature measurement method for a temperature-sensing lightning protection combined insulator as described in claim 1, characterized in that, Based on the following formula, deflection angle data is extracted from the schlieren image of the discharge channel using Abelian integration: ； in, R Let be the boundary radius of the discharge channel. r Radial distance, x As the independent variable; The process of processing the deflection angle data using an improved Gauss-Legendal algorithm to reconstruct the spatial distribution of the refractive index of the discharge channel, thereby obtaining the radial distribution of the refractive index of the discharge channel, specifically includes: The inverse Abelian transform equation is determined by Abelian integral based on the following formula: ； in, γ ( r ( ) represents the radial distribution of refractive index. γ 0 represents the background refractive index of the measured space. α ( x () represents the deflection angle data; The integration interval of the inverse Abelian transform equation is split into smaller parts, and the integration step size is dynamically adjusted adaptively according to the gradient change of the deflection angle data. A weighting function adapted to the refractive index distribution is introduced to suppress numerical calculation errors at singularities, thus obtaining the inverse deflection angle data. Through an iterative optimization process, the residual between the reversed deflection angle data and the deflection angle data is made to meet the preset threshold condition, thereby obtaining the radial distribution of the refractive index of the discharge channel.

5. The temperature measurement method for a temperature-sensing lightning protection combined insulator as described in claim 1, characterized in that, The process involves inverting the radial refractive index distribution of the discharge channel using a plasma composition model to capture the quantitative relationship between the gas temperature data of the discharge channel and the refractive index difference of the gas particles, thereby obtaining the gas temperature data of the discharge channel. Specifically, this includes: Based on the following formula, the corresponding particle number density and gas temperature data are determined according to the spatial distribution of the refractive index of the discharge channel obtained by the calibrated schlieren thermography system: ； ； ； ； in, n AB As molecules, n A and n B The number density of the molecular dissociation products. m AB The mass of molecule AB, m A and m B Let A and B be the masses. Let be the partition function of molecule AB. Z A and Z B Let be the partition function of atoms A and B. E LAB The energy required for the dissociation of molecules AB. k Boltzmann's constant, T e For electron temperature, The number density of unionized positive particles. n i The number density of unionized particles. For the positive partition function of the plasma, Z i For the plasma partition function, E di It is ionization energy. n e The total electron number density in the plasma. n i +j The positive dissociation density in the plasma. j is the charge coefficient of a positive ion. P For gas pressure, N The total number of particles in the gas. V Let be the volume of the gas. R con This is the universal gas constant. N A Let Avogadro's constant be 1. T gas For gas temperature, n zong The total particle number density in the plasma. n s In order to be with the first s Related to elements l The particle number density of each component n p In order to be with the first p Related to elements m The particle number density of each component C These are the stoichiometric constants of the elements; Based on the following equation, the radial distribution of the refractive index of the discharge channel is inverted using a plasma composition model to obtain the gas temperature data of the discharge channel: ； in, where is the refractive index and e is the electron. a For atoms, m As molecules, i These are ions, where O represents oxygen atoms and N represents nitrogen atoms. L os For the Loschmidt number, λ The incident light wavelength, n For particle number density, A , B and χ is a relevant constant.

6. The temperature measurement method for a temperature-sensing lightning protection combined insulator as described in claim 1, characterized in that, The method, based on the temperature rise data of the wet pollution interface and the gas temperature data of the discharge channel, determines the evolution law of the wet pollution interface and arc temperature during the arc initiation to flashover formation process of the temperature-sensing lightning protection combined insulator under different pollution levels, specifically including: The temperature rise data of the wet interface was aligned with the schlieren image of the discharge channel along the time axis. Based on the characteristics of arc development, the discharge process of the discharge channel was divided into the arc initiation stage, the arc development stage, and the flashover formation stage. According to the set range of equivalent salt density, the wet contamination interface is divided into lightly contaminated, moderately contaminated, and heavily contaminated groups. The temperature rise rate, temperature peak and heat accumulation of the wet contamination interface, as well as the temperature peak and temperature spatial distribution characteristics of the discharge channel, are extracted for each discharge stage under each contamination level. Based on the time delay relationship between the temperature rise of the wet interface and the temperature of the discharge channel under each level of pollution, the trend of the temperature ratio change, and the coupling coefficient between the temperature rise rate of the wet interface and the temperature rise rate of the arc channel, the initial temperature of the wet interface at the moment of arc initiation and the spatial relative position of the high temperature zone of the arc channel and the high temperature zone of the wet interface are extracted. Based on the synchronicity or lag of the evolution of wet interface temperature and discharge channel temperature with the discharge stage under different pollution levels, the influence of wet interface heat accumulation on the temperature rise of the arc channel is analyzed, so as to summarize the coupling mode between wet interface temperature and discharge channel temperature from the arc initiation stage to the flashover formation process and obtain the evolution law.

7. A temperature measurement system for a temperature-sensing lightning protection combined insulator, characterized in that, include: The insulation interface measurement module is used to collect temperature data of the insulation interface in real time through a micro temperature sensing chip array, and process the temperature data of the insulation interface through Fourier algorithm to determine the temperature distribution characteristics of the wet and dirty interface and obtain the temperature rise data of the wet and dirty interface. The discharge channel measurement module is used to acquire schlieren images of the discharge channel through a calibrated schlieren thermometry system, and extract deflection angle data from the schlieren images of the discharge channel through Abelian integration. The deflection angle data is processed using an improved Gauss-Legendal algorithm to reconstruct the spatial distribution of the refractive index of the discharge channel, obtaining the radial distribution of the refractive index of the discharge channel. The radial distribution of the refractive index of the discharge channel is inverted using a plasma composition model to capture the quantitative relationship between the gas temperature data of the discharge channel and the refractive index difference of gas particles, obtaining the gas temperature data of the discharge channel. The improved Gauss-Legendal algorithm is obtained by dynamically adjusting the integration step size and introducing a weighting function adapted to the refractive index distribution based on the Gauss-Legendal algorithm. The temperature measurement module is used to determine the evolution of the temperature of the wet and polluted interface and the arc during the arc initiation to flashover formation process of the temperature-sensing lightning protection combined insulator under different pollution levels, based on the temperature rise data of the wet and polluted interface and the gas temperature data of the discharge channel.

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