Environment-friendly cabinet temperature rise modeling method for dynamically reflecting microcosmic change of contact structure

Abstract

The invention discloses an environment-friendly cabinet temperature rise modeling method capable of dynamically reflecting microcosmic change of a contact structure. The method comprises the following steps: performing parameter measurement on an environment-friendly cabinet object, reasonably simplifying the structure, and performing physical modeling to obtain a basic model; carrying out electric-thermal-flow multi-physics field coupling, setting an equipment material, and calculating an electric wear parameter of the Baharami electric contact model at the same time; applying a finite element model boundary condition and carrying out grid division; setting a temperature probe and operating COMSOL to record simulation numerical values, and meanwhile, controlling variables to carry out a temperature rise experiment on the same equipment and carrying out temperature measurement on the same point; modifying and optimizing the basic model when error analysis and judgment do not meet requirements; and if yes, adjusting parameters according to different wear degrees to restore the working condition state of the equipment in each stage, so as to adjust the surface structure parameters of the basic model, and further fitting to obtain a contact structure of each stage, importing the contact structure into a finite element model for operation simulation to obtain a temperature distribution rule so as to analyze temperature rise characteristics. According to the invention, temperature rise abnormity in long-time operation can be better predicted and prevented.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical equipment, and in particular to a temperature rise modeling method for an environmental protection cabinet that dynamically reflects microscopic changes in a contact structure. Background Art

[0002] Gas insulated switchgear (GIS) is widely used in power systems. In the development and testing of high-voltage GIS equipment, on-site experiments are costly and pose safety risks. As an important research method, simulation provides a safer testing environment. Finite element simulation can restore various processes in a virtual environment and avoid the high cost of actual testing, reducing resource waste.

[0003] Domestic and foreign researchers use simulation software to conduct multi-physics coupling simulation on various types of switchgear, and apply different boundary conditions according to actual conditions, so as to solve the overall or local parameters and distribution laws of the equipment under various working conditions, which serves as the theoretical basis for equipment improvement. The characteristic of the inflatable cabinet is that the gas box structure seals the primary circuit part, and the interior is filled with slightly positive pressure gas as an insulating medium. Such a structure makes the environmental protection cabinet more adaptable in extreme environments such as high altitude, humidity, and pollution, less susceptible to environmental factors, and has a wider range of applications. However, such a structure also makes it difficult to discharge the heat generated by the current-carrying conductor, increasing the probability of abnormal temperature rise in GIS. The temperature rise anomaly and temperature rise characteristic optimization of switchgear have always been technical difficulties. From the simulation level, it is necessary to ensure that the error between the results of finite element simulation and the actual experiment is as small as possible. The simulation analysis method of multi-physics coupling is adopted to restore the real state of the equipment under different operating conditions, so as to obtain the overall or local parameters and distribution laws of different types of GIS equipment under various working conditions.

[0004] The researchers have comprehensively explored the performance of GIS equipment by actively conducting multi-physics field simulation research, especially the coupling simulation between electric field and thermal field. The research process of finite element simulation is usually to consider two or three physical fields as required, simplify and construct according to the actual model, set materials and divide the grid reasonably as required, and finally apply boundary conditions to complete the numerical solution and analyze the simulation results to solve practical problems. For the problems existing in the equipment, the analysis will be based on the simulation, and a scientific and reasonable optimization method will be proposed. It is helpful to quickly verify and modify the design scheme, evaluate the impact of different parameters on the system behavior, determine the optimal design parameters, and save development cycle and time cost. Simulate extreme conditions that are difficult to achieve in the laboratory, such as high temperature and high pressure, to explore the performance of switchgear under different working conditions. The simulation of multi-physics field coupling and operating environment through simulation software is helpful to improve equipment design, prevent potential problems, and ensure reliable power supply of power systems. By precisely controlling the experimental conditions, including environment, parameters and variables, combining the numerical and image results of the simulation for analysis, and verifying with physical comparison, it helps researchers better understand the working principle of the environmental protection cabinet.

[0005] Operation experience shows that due to the existence of separable contact points inside GIS, the highest temperature is usually distributed near the circuit breaker contacts. Long-term switching of large currents will cause significant changes in the surface structure of the circuit breaker contacts. The contraction effect of the current causes an abnormal surge in local temperature and even burns the internal components of the GIS. Local heating failures caused by contact surface degradation account for 29% of all GIS failures and are the most common type of failure. During the process of the circuit breaker switching on and off the arc, the high temperature will cause the metal part of the contact to melt and vaporize. This degradation process is called electrical wear of the contact surface.

[0006] Traditional simulation methods are mostly based on the finite element coupling between electric field and thermal field, and explore the temperature distribution of different types of equipment. However, the research object is usually GIS equipment with traditional SF6 gas as the insulating medium. The research on the emerging environmentally friendly gas insulated cabinet is not sufficient. Due to the different physical and chemical properties, environmentally friendly gases will have different performances under the same external conditions. On the other hand, as one of the basic reasons for the aggravation of temperature rise, the value of contact resistance is not constant for a long time, but fluctuates with the increase of operating time. For the phenomenon of abnormal temperature rise, related studies focus on improving external ventilation and improving heat dissipation efficiency, but do not study the continuous impact of electrical wear on equipment from the root cause. The deterioration process of this contact structure is manifested as a continuous increase in contact resistance, which brings higher Joule heat. In the research that considers this phenomenon, most of them use the Holm formula. However, in fact, the contact between the moving and static contacts is not flat. During the separation and combination of the moving and static contacts, the arc generates high temperature and sparks, which leads to erosion and vaporization of the contact coating material, forming gas and plasma, and further increasing the surface roughness. As an empirical formula, for the contact surface of such a complex structure, the Holm formula will introduce non-negligible errors, directly causing the finite element simulation results to deviate from the true value.

[0007] At present, the following problems exist in the research on the abnormal temperature rise of separable contact surfaces using simulation methods:

[0008] 1) In traditional simulations, the contact surface is usually simplified to a smooth, uniform plane, assuming an idealized contact state, ignoring the microscopic bumps and uneven distribution of contact points on the actual surface. In reality, only some areas on the contact surface are in true contact, and the distribution of contact points is affected by factors such as surface roughness and pressure, forming local "hotspot" areas. Such simplified processing underestimates the contact resistance and local temperature rise, and cannot accurately reflect the temperature distribution under actual working conditions. Especially under high load or long-term operation, this neglect may lead to insufficient prediction of abnormal temperature rise.

[0009] 2) In existing research, the study of abnormal local temperature rise on the contact surface is often limited to short-term simulation, ignoring the impact of long-term operation on the temperature rise characteristics. Especially during the opening and closing operation, the long-term loss and degradation of the contacts caused by the arc phenomenon have not been fully considered. Most studies focus on simulation under a single working condition, fixed parameters and conditions, and fail to dynamically track the temperature rise changes during the contact degradation process. This limitation has led to the failure of existing research to fully capture the changes in the temperature rise characteristics of the equipment under actual working conditions, and to effectively predict the temperature rise anomalies that may occur during long-term operation.

[0010] 3) Most current simulation studies focus on conventional gas-insulated switchgear, usually using SF with high global warming potential (GWP). 6Gas is used as an insulating medium. Its internal structure and material selection also mostly follow traditional designs, lacking the exploration of environmentally friendly materials and structures. This limitation makes traditional research unable to adapt to the growing environmental protection needs and application scenarios of new materials.

[0011] In order to further explore the continuous impact of the degradation process of electrical wear on the overall temperature rise of the equipment, it is necessary to develop an accurate temperature rise modeling method to evaluate the process of microscopic changes in the contacts. Summary of the invention

[0012] The object of the present invention is to provide a temperature rise modeling method for an environmental protection cabinet that dynamically reflects microscopic changes in contact structures.

[0013] The technical solution adopted by the present invention is:

[0014] A temperature rise modeling method for an environmental protection cabinet that dynamically reflects microscopic changes in contact structure comprises the following steps:

[0015] Step 1, measure parameters of the dry air insulated environmental protection cabinet in real object, reasonably simplify the structure and perform physical modeling to obtain the basic model;

[0016] Furthermore, in step 1, physical modeling (1) ensure the dimensional consistency of the numerical model by measuring the physical parameters of the physical device in detail, and retain the shape and geometric features of the conductor loop; (2) accurately restore the contact structure and simplify unimportant details. For example, structures such as screws, bolts, and circuit surface textures will significantly increase the workload of simulation calculations, but have very little effect on the results and can be simplified. (3) For parts with large volume and complex internal structure, such as operating mechanisms, the internal details are not within the scope of study and are simplified.

[0017] Step 2, conduct electrical-thermal-fluid multi-physics field coupling on the basic model and set the equipment material, and calculate the electrical wear parameters of the Baharami electrical contact model;

[0018] Step 3, applying finite element model boundary conditions to the basic model and completing meshing;

[0019] Specifically, the complete mesh includes 330,279 area elements, 67,944 boundary elements, and 6,187 edge elements, which can meet the simulation requirements. The number of degrees of freedom solved is 60,490, including 71,454 internal degrees of freedom.

[0020] Step 4: Set the temperature probe and run COMSOL to record the simulation value. At the same time, control the variables to conduct a buried point heating experiment inside the same model of environmental protection cabinet and measure the temperature at the same point.

[0021] Step 5, perform error analysis on the simulation data and the measurement data to determine whether the accuracy of the basic model meets the requirements; if yes, proceed to step 6; otherwise, check, modify and optimize the basic model and proceed to step 2;

[0022] Step 6, adjusting parameters according to parameter distributions of different wear degrees to dynamically restore the working conditions of the equipment at each stage of its service life;

[0023] Step 7, adjusting the surface structure parameters of the basic model based on the working conditions of each stage, and obtaining the contact structure of each stage by fitting the minimum discrete unit;

[0024] Step 8: Import the contact structures at each stage of fitting into the finite element model and run simulation to obtain the temperature distribution law in order to analyze the temperature rise characteristics.

[0025] Furthermore, the environmental protection cabinet consists of an operating mechanism room, a cable room, a busbar room, an instrument room and a pressure relief room; the busbar room is sealed by a gas box and maintains a micro-positive pressure of 0.3Mpa. The busbar room contains a three-phase busbar, a circuit breaker, an isolating knife switch, an insulating bushing and a fixed partition.

[0026] Furthermore, in step 2, the electrical wear parameters of the Baharami electrical contact model are calculated using mathematical software. As a feasible implementation, MATLAB software may be selected to perform relevant calculations.

[0027] Furthermore, the formula for calculating the electrical wear parameter of the Baharami electrical contact model in step 2 is as follows:

[0028]

[0029] n s =1 / 16(σ / m) 2 [exp(-2λ 2 ) / (e rfc λ)]A (4)

[0030] Where ρ represents the resistivity of the contact material; a s Indicates the radius of the bulge; n s represents the number of protrusions in the discrete unit; λ represents the contact gap characteristic function; γ represents the equivalent distance between the center line of the rigid sphere and the elastic rough surface and the smooth rigid surface of the discrete unit; σ represents the equivalent roughness; e rfc represents the Gaussian error function; A represents the nominal contact area; m represents the slope of the tiny contact point on the contact along the section.

[0031] Furthermore, in step 4, the rated current of the environmental protection cabinet is 630A, and the temperature rise test is performed at 1.1 times the rated current; the operating environment temperature is set to room temperature, that is, 298.15K.

[0032] Furthermore, the surface structure parameters in step 7 include coarse-grainedness, the number of contact micro-humps, and the radius.

[0033] Furthermore, in step 7, by investigating the same type of environmental protection cabinets with different service periods, the distribution characteristics of convex hills in different wear states are measured, and the parameters of the temperature rise model are set based on this as a reference value to achieve simulation of different working conditions of the equipment.

[0034] The present invention adopts the above technical scheme and has the following technical features: 1) A temperature rise model that accurately reflects the changes in the microscopic morphology of the contact surface is proposed. By establishing a more accurate contact surface model, the actual microscopic concavities and convexities of the contact surface and the non-uniform distribution of the contact points are considered to more truly reflect the temperature rise distribution under actual working conditions. 2) The simulation method can dynamically fit the temperature rise changes in long-term operation. A model that can dynamically track the temperature rise changes caused by arc effects and long-term degradation of contacts during opening and closing operations is designed to better predict and prevent temperature rise anomalies during long-term operation. 3) Suitable for efficient simulation of environmentally friendly gas-insulated equipment. For a new type of environmentally friendly gas-insulated switchgear with 12kV dry air insulation, a simulation model with high efficiency, low error, good convergence and flexibility is proposed. This method is not only suitable for the application scenarios of new environmentally friendly materials, but also provides important support for the design improvement and reliable power supply of related equipment, while helping researchers to deeply understand the operating mechanism of environmentally friendly equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments;

[0036] Figure 1 It is a structural schematic diagram of a method for modeling temperature rise of an environmental protection cabinet that dynamically reflects microscopic changes in contact structure according to the present invention;

[0037] Figure 2 It is a schematic diagram of the overall part of the environmental protection cabinet divided into grids according to the present invention;

[0038] Figure 3 It is a schematic diagram of a primary circuit portion of the grid division of the present invention;

[0039] Figure 4 It is a physical schematic diagram of electrical wear on the contact surface of the present invention;

[0040] Figure 5 A schematic diagram of the uneven contact microscopic surface of the present invention;

[0041] Figure 6 It is a schematic diagram of the contact structure fitting principle of the present invention;

[0042] Figure 7It is a schematic diagram for comparing the temperature distribution of the equipment under different degrees of electrical wear;

[0043] Figure 8 Schematic diagram of temperature rise comparison at different locations between temperature rise simulation and experimental temperature measurement;

[0044] Fig. 9 Schematic diagram of the comparison of temperature results at different locations of temperature rise simulation and experimental temperature measurement. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0046] like Figures 1 to 9 As shown in one of the figures, the present invention discloses a temperature rise modeling method for an environmental protection cabinet that dynamically reflects the microscopic changes of the contact structure, which includes the following steps:

[0047] Step 1, measure parameters of the dry air insulated environmental protection cabinet in real object, reasonably simplify the structure and perform physical modeling to obtain the basic model;

[0048] Furthermore, in step 1, physical modeling (1) ensure the dimensional consistency of the numerical model by measuring the physical parameters of the physical device in detail, and retain the shape and geometric features of the conductor loop; (2) accurately restore the contact structure and simplify unimportant details. For example, structures such as screws, bolts, and circuit surface textures will significantly increase the workload of simulation calculations, but have very little effect on the results and can be simplified. (3) For parts with large volume and complex internal structure, such as operating mechanisms, the internal details are not within the scope of study and are simplified.

[0049] Step 2, conduct electrical-thermal-fluid multi-physics field coupling on the basic model and set the equipment material, and calculate the electrical wear parameters of the Baharami electrical contact model;

[0050] Step 3, applying finite element model boundary conditions to the basic model and completing meshing;

[0051] Specifically, the complete mesh includes 330,279 area elements, 67,944 boundary elements, and 6,187 edge elements, which can meet the simulation requirements. The number of degrees of freedom solved is 60,490, including 71,454 internal degrees of freedom.

[0052] Step 4: Set the temperature probe and run COMSOL to record the simulation value. At the same time, control the variables to conduct a buried point heating experiment inside the same model of environmental protection cabinet and measure the temperature at the same point.

[0053] Step 5, perform error analysis on the simulation data and the measurement data to determine whether the accuracy of the basic model meets the requirements; if yes, proceed to step 6; otherwise, check, modify and optimize the basic model and proceed to step 2;

[0054] Step 6, adjusting parameters according to parameter distributions of different wear degrees to dynamically restore the working conditions of the equipment at each stage of its service life;

[0055] Step 7, adjusting the surface structure parameters of the basic model based on the working conditions of each stage, and obtaining the contact structure of each stage by fitting the minimum discrete unit;

[0056] Step 8: Import the contact structures at each stage of fitting into the finite element model and run simulation to obtain the temperature distribution law in order to analyze the temperature rise characteristics.

[0057] Furthermore, the environmental protection cabinet consists of an operating mechanism room, a cable room, a busbar room, an instrument room and a pressure relief room; the busbar room is sealed by a gas box and maintains a micro-positive pressure of 0.3Mpa. The busbar room contains a three-phase busbar, a circuit breaker, an isolating knife switch, an insulating bushing and a fixed partition.

[0058] Furthermore, in step 2, the electrical wear parameters of the Baharami electrical contact model are calculated using mathematical software. As a feasible implementation, MATLAB software may be selected to perform relevant calculations.

[0059] Furthermore, the formula for calculating the electrical wear parameters of the Baharami electrical contact model in step 2 is as follows:

[0060]

[0061] N s =1 / 16(σ / m) 2 [exp(-2λ 2 ) / (e rfc λ)]A (4)

[0062] Where ρ represents the resistivity of the contact material; A s Indicates the radius of the bulge; N s represents the number of protrusions in the discrete unit; λ represents the contact gap characteristic function; γ represents the equivalent distance between the center line of the rigid sphere and the elastic rough surface and the smooth rigid surface of the discrete unit; σ represents the equivalent roughness; e rfc represents the Gaussian error function; A represents the nominal contact area; m represents the slope of the tiny contact point on the contact along the section.

[0063] Furthermore, in step 4, the rated current of the environmental protection cabinet is 630A, and the temperature rise test is performed at 1.1 times the rated current; the operating environment temperature is set to room temperature, that is, 298.15K.

[0064] Furthermore, the surface structure parameters in step 7 include coarse-grainedness, the number of contact micro-humps, and the radius.

[0065] Furthermore, in step 7, by investigating the same type of environmental protection cabinets with different service periods, the distribution characteristics of convex hills in different wear states are measured, and the parameters of the temperature rise model are set based on this as a reference value to achieve simulation of different working conditions of the equipment.

[0066] Furthermore, in order to verify the accuracy of the simulation values, a temperature rise control experiment was conducted on the environmental protection cabinet prototype. The environmental protection cabinet prototypes under two working conditions were selected for temperature and temperature rise error control experiments respectively;

[0067] The specific principle of the present invention is described in detail below:

[0068] like Figure 1 The cabinet structure shown in the figure is a temperature rise modeling method for environmental protection cabinets that dynamically reflects the microscopic changes in the contact structure. The 12kV dry air insulated switchgear is used as the research object. Its structure consists of an operating mechanism room, a cable room, a busbar room, an instrument room, and a pressure relief room. The busbar room is sealed by an air box and maintains a micro-positive pressure of 0.3Mpa, including a three-phase busbar, a circuit breaker, an isolating knife switch, an insulating bushing, and a fixed partition.

[0069] As the basis of finite element simulation research, in order to ensure the success rate of meshing and the efficiency and convergence speed of finite element calculation, the physical modeling of the environmentally friendly GIS follows the following principles:

[0070] 1) Detailed measurement of the physical parameters of the physical device to ensure the dimensional consistency of the numerical model and preserve the shape and geometric characteristics of the conductor loop.

[0071] 2) Accurately restore the contact structure and simplify unimportant details. Structures such as screws, bolts, and circuit surface textures will significantly increase the workload of simulation calculations, but have very little effect on the results.

[0072] 3) For parts that are large in size and have complex internal structures, such as operating mechanisms, the internal details are not within the scope of study and are simplified.

[0073] The basic model after material setting and meshing is shown in the figure below. The complete mesh includes 330,279 regional elements, 67,944 boundary elements, and 6,187 edge elements, which can meet the simulation requirements. The degrees of freedom to be solved are 60,490, including 71,454 internal degrees of freedom, such as Figure 2 Or as shown in 3.

[0074] The contact points between the moving and static contacts of the circuit breaker inside the switchgear are not flat, which is also the main reason why the temperature rise fitting of the equipment is not accurate enough in many studies. Due to the arc between the moving and static contacts, the high temperature and sparks generated lead to the erosion and vaporization of the coating material, the surface will become more and more rough and pitted, the structure will become more and more complex, and electrical wear will occur. Structurally, it is mainly manifested in the appearance of a large number of tiny bumps on the contacts, the surface is no longer flat, and the silver coating is ablated. The ablation will leave a number of bumps scattered on the surface of the moving and static contacts, increasing the roughness and aggravating the contraction effect of the current, resulting in a decrease in the conductivity and breaking capacity of the contacts and an increase in heat generation. For example Figure 4 As shown in the figure, the environmental protection cabinet contacts are subject to severe electrical wear. Figure 5 The figure shows the microscopic contact surface of the moving and static contacts after being subjected to electrical wear.

[0075] For scenarios where accuracy is not high, many studies use the Holm formula to simulate the contact between surfaces:

[0076] R J =K / (0.102F) m (5)

[0077] Wherein, m is the contact coefficient, which is 0.5 for point contact, 0.5 to 1 for line contact, and 1 for surface contact; K is a coefficient determined by the material.

[0078] However, for contact surfaces with complex structures, the Holm formula will introduce significant errors. In addition, considering the need to dynamically fit the degradation phenomenon of electrical wear and restore the true state of the contact under different working conditions, it is necessary to ensure that the error of the simulation model is small enough and introduce a more complex and accurate model to fit the contact structure. After research and analysis, the Baharami electrical contact model can better restore the structural changes of the contact. The formula for calculating the resistance of the rough contact surface based on this model is as follows:

[0079]

[0080] n s =1 / 16(σ / m) 2 [exp(-2λ 2 ) / (e rfc λ)]A (4)

[0081] In formulas (1)-(4), ρ represents the resistivity of the contact material; a s Indicates the radius of the bulge; n s represents the number of protrusions in the discrete unit; λ represents the contact gap characteristic function; γ represents the equivalent distance between the center line of the rigid sphere and the elastic rough surface and the smooth rigid surface of the discrete unit; σ represents the equivalent roughness; e rfc represents the Gaussian error function; A represents the nominal contact area.

[0082] like Figure 6 According to the fitting principle shown above, the calculation results of this theoretical model for complex irregular surfaces have smaller errors than the actual values. Its advantage is that it can well restore the uneven contacts produced by electrical wear on the contact surface. In this model, m represents the slope of the tiny contact on the contact along the section, that is, the ratio of the ordinate and abscissa, which can reflect the roughness of the surface texture; σ is the equivalent roughness of the contact surface, which can reflect the height fluctuation of the surface convex hillocks left by electrical wear along the standard surface. As the service time of the environmental protection cabinet increases, the convex hillocks between the moving and static contacts will become more and more dense, and their radius and height will also increase accordingly, forming complex microscopic gullies. Therefore, by controlling parameters such as contact roughness, contact radius, spacing, number and distribution of convex hillocks, the state of the contact under different working conditions can be restored.

[0083] The parameter settings are shown in Table 1. The parameters are adjusted and substituted into the finite element model for simulation. The fitting model used contains multiple variables and function integral calculations, and the design code is executed by MATLAB. On the other hand, by investigating the same type of environmental protection cabinets with different service periods, the distribution characteristics of convex hills in different wear states are measured, and this is used as a reference value to set the parameters of the temperature rise model to achieve simulation of different working conditions of the equipment.

[0084] Table 1 Wear parameter settings

[0085] Degree of wear Contact roughness / μΩ Equivalent contact radius / m Equivalent spacing / mm Resistivity / ρ·m slight 1 0.023 0.1 1.6e-8 normal 2 0.022 0.1 1.6e-8 More serious 5 0.021 0.11 1.6e-8 serious 7 0.02 0.12 1.61e-8

[0086] As shown in Table 2, the distribution of micro-humps simulated by the model equivalent to different wear states

[0087] Table 2. Hillock distribution settings

[0088] Electrical wear degree Convex hill radius / μm Number of hillocks slight 0.28 104 normal 0.64 402 More serious 1.26 633 serious 1.54 1045

[0089] After completing the multi-physics field coupling setting of the environmental protection inflatable cabinet model, the above parameters run in MATLAB are imported into the temperature rise model established in the simulation software. The rated current of this model of environmental protection cabinet is 630A, and the temperature rise test is carried out at 1.1 times the rated current. The operating environment temperature is set to room temperature, that is, 298.15K.

[0090] like Figure 7 As shown in the figure, the simulation process is repeated to simulate the process of the environmental cabinet from slight to severe electrical wear dynamically affecting the temperature rise of the equipment. Several groups of simulation experiments are carried out to obtain the highest temperature point and heat distribution value of the environmental cabinet. In order to verify the accuracy of the simulation value, a temperature rise control experiment is carried out on the environmental cabinet prototype. The temperature measurement point is installed and connected to the temperature acquisition system.

[0091] The environmental protection cabinet prototypes under two working conditions were selected for temperature and temperature rise error comparison experiments. Figure 8 As shown in Figure 9, the temperature rise error distribution of each phase point under two working conditions. Figure 8 and Fig. 9 Under two different operating conditions, by comparing the temperature rise changes and temperature conditions of the test values ​​and simulation results at key points, curves were drawn to verify the accuracy of the model.

[0092] According to the two working conditions, the temperature rise simulation and experimental temperature measurement results of the three phases A, B, and C are carried out, and it can be concluded that the errors are relatively small. The shape fitting effect of the three-phase temperature rise curve is good, and the simulation error of each location is controlled within a very small range. The structure is relatively ideal, which verifies the effectiveness of the model established in this study and the feasibility of the simulation method. For the increasing electrical wear, the model can fit well.

[0093] Based on the above analysis, the temperature rise modeling method developed in this study is specifically aimed at the complex working conditions of the contacts of environmentally friendly gas insulated switchgear (GIS), with special attention paid to the dynamic simulation of the microscopic changes in the surface contact structure and its temperature rise behavior. Compared with the traditional modeling method, the model proposed in this invention shows good accuracy and adaptability when dealing with complex factors such as microscopic bumps on the contact surface, non-uniform distribution of contact points, and gradual increase in electrical wear.

[0094] After temperature rise simulation and experimental temperature measurement of key points of phases A, B, and C under two different wear conditions, the results show that the error between the simulation value and the measured value is negligible, and the three-phase temperature rise curve is not only highly consistent in the overall trend, but also well fitted in the details. The high accuracy and reliability of the model are verified by the fitting results, and its ability to restore temperature rise changes in dynamic simulation of long-term operation is also proved. The accuracy and effectiveness of the temperature rise prediction of the equipment under high load or long-term operation is ensured.

[0095] The method of the present invention shows unique advantages in the design and optimization of environmentally friendly gas-insulated GIS, and provides technical support for future power equipment design and fault prediction. The method has high adaptability, provides more realistic and detailed temperature rise prediction, can dynamically respond to the changing laws of the equipment throughout its life cycle, and provides technical support for preventive maintenance and optimization design of the equipment.

[0096] During the design stage and operation process, the present invention can provide a more accurate theoretical basis, and it is expected that new technologies for extending the service life of environmentally friendly GIS equipment and reducing operating costs will be further studied on the basis of the present invention, thereby improving the safety and reliability of the target equipment. The high-precision temperature rise model established by the present invention provides researchers with a reliable research framework, which can be used to perform temperature rise analysis under conditions of increased contact wear or other complex working conditions. The universality and adaptability of this model enable researchers to apply it to different equipment and conditions, further enriching their research methods. The temperature rise of the dry air insulated environmental protection cabinet is modeled by dynamically simulating the changes in the contact microstructure, breaking through the limitations of the traditional model. Against the background of growing environmental protection needs, it has played a role in promoting the research and development and application of new power equipment. This makes this method of important strategic significance and practical value in current and future technological developments.

[0097] Improved technology: Based on the basic technical solution, the present invention further provides a number of optimized implementations, which show significant advantages by improving the adaptability, accuracy and practicality of the simulation model, especially in the application of environmental media and dynamic working condition processing.

[0098] Optimization implementation method 1: local microstructure simulation of other separable contact surfaces in the switch device.

[0099] In the basic implementation, the simulation model is mainly used for the temperature rise modeling of the main contacts of the environmental protection cabinet. This implementation extends the simulation model to other detachable contact surfaces in the switchgear, such as the disconnector knife switch, the busbar fitting surface, etc., and by fitting and simulating the temperature rise of the local surface microstructures of these components, the model can be widely applied to a variety of key components. This optimization measure further enhances the applicability of the model, enabling it to more accurately reflect the temperature rise characteristics of each component under different working conditions, thereby improving the operating reliability of the overall equipment.

[0100] Optimized implementation method two: expanded application of environmentally friendly media.

[0101] In the basic implementation, the simulation model is developed for 12kV environmentally friendly switchgear with dry air as the insulating medium. This implementation extends the model to switchgear using other environmentally friendly insulating media, such as nitrogen, carbon dioxide, etc. Through its application in a variety of environmentally friendly gas insulating media, this implementation further improves the multi-media adaptability of the model, and demonstrates higher application value in environmental protection, supporting the promotion and application of environmentally friendly power equipment.

[0102] Optimization implementation method three: simulation description of dynamic processes in the environmental protection cabinet.

[0103] In the basic implementation, the simulation model is mainly used for dynamic temperature rise analysis under different working conditions of electrical wear. This implementation applies the model to the dynamic process simulation of other similar physical phenomena in the environmental protection cabinet by adjusting the parameters in the theoretical model. This optimization measure enhances the responsiveness of the model under other dynamic conditions, reflects the performance of the equipment, and effectively improves the predictive ability of the equipment in long-term operation.

[0104] Optimization implementation method four: parameter optimization and model adaptability enhancement.

[0105] In the basic implementation, the simulation model uses a preset model for temperature rise analysis. This implementation improves the adaptability and prediction accuracy of the model under different working conditions by optimizing and adjusting the model algorithm. This optimization measure enables the model to dynamically adjust parameters according to real-time data, improves its adaptability to variable working conditions, and significantly improves the efficiency of simulation calculations while ensuring accuracy, meeting the demand for rapid response in practical applications.

[0106] Effect description: According to the finite element simulation results, the temperature of the 12kV environmental protection cabinet with dry air as the insulating medium is within the normal range and the distribution is relatively reasonable. In order to verify the correctness of the results, a temperature rise test was carried out on the same model of environmental protection cabinet.

[0107] The measured results show that the temperature of the equipment will not stabilize quickly after it is put into operation. The temperature rises rapidly in the first 1.5 hours, then slows down significantly and gradually stabilizes in the next 1 to 2 hours. Temperature readings are performed at key points, including the three-phase insulating bushings, circuit breaker contacts, and disconnector switches. At the same time, temperature probes are set at the same points of the established temperature rise model in the simulation software COMSOL Multiphysics to record the simulation values. Error analysis is then performed.

[0108] After comparison, the temperature simulation error of each point is controlled within a small range, not exceeding 5%. Considering the normal temperature fluctuation and the possible errors in the experimental process, the effectiveness of the model established by the present invention and the correctness of the research are basically confirmed. The simulation values ​​and experimental results are shown in Table 3.

[0109] Table 3 Error comparison

[0110]

[0111] From the above data, it can be seen that the error range between the simulation results and the measured values ​​is small. In most cases, the error is between 1-3K, and the error percentage is less than 5%, indicating that the simulation model has high accuracy. Especially in the simulation of the insulating bushing and the circuit breaker contact, the error is kept at a low level, showing the reliability and accuracy of the simulation model in simulating these two components.

[0112] In addition, although the error of the isolation switch is slightly higher, it is still within an acceptable range.

[0113] In summary, this simulation method can effectively reflect the actual temperature rise characteristics of the equipment, proving its efficiency and practicality in the research of environmentally friendly gas-insulated equipment. This environmental cabinet temperature rise modeling method that dynamically reflects the microscopic changes in the contact structure is of great value in the design optimization of similar equipment and the prediction of temperature rise anomalies.

[0114] The present invention adopts the above technical scheme and has the following technical features: 1) A temperature rise model that accurately reflects the changes in the microscopic morphology of the contact surface is proposed. By establishing a more accurate contact surface model, the actual microscopic concavities and convexities of the contact surface and the non-uniform distribution of the contact points are considered to more truly reflect the temperature rise distribution under actual working conditions. 2) The simulation method can dynamically fit the temperature rise changes in long-term operation. A model that can dynamically track the temperature rise changes caused by arc effects and long-term degradation of contacts during opening and closing operations is designed to better predict and prevent temperature rise anomalies during long-term operation. 3) Suitable for efficient simulation of environmentally friendly gas-insulated equipment. For a new type of environmentally friendly gas-insulated switchgear with 12kV dry air insulation, a simulation model with high efficiency, low error, good convergence and flexibility is proposed. This method is not only suitable for the application scenarios of new environmentally friendly materials, but also provides important support for the design improvement and reliable power supply of related equipment, while helping researchers to deeply understand the operating mechanism of environmentally friendly equipment.

[0115] Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. In the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the present application is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians of the art without making creative work are within the scope of protection of the present application.

Claims

1. A temperature rise modeling method for an environmental protection cabinet that dynamically reflects the microscopic changes in the contact structure, characterized in that: It includes the following steps: Step 1, measure parameters of the dry air insulated environmental protection cabinet in real object, reasonably simplify the structure and perform physical modeling to obtain the basic model; Step 2, conduct electrical-thermal-fluid multi-physics field coupling on the basic model and set the equipment material, and calculate the electrical wear parameters of the Baharami electrical contact model; Step 3, applying finite element model boundary conditions to the basic model and completing meshing; Step 4: Set the temperature probe and run COMSOL to record the simulation value. At the same time, control the variables to conduct a buried point heating experiment inside the same model of environmental protection cabinet and measure the temperature at the same point; Step 5, perform error analysis on the simulation data and the measurement data to determine whether the accuracy of the basic model meets the requirements; if yes, proceed to step 6; otherwise, check, modify and optimize the basic model and proceed to step 2; Step 6, adjusting parameters according to parameter distributions of different wear degrees to dynamically restore the working conditions of the equipment at each stage of its service life; Step 7, adjusting the surface structure parameters of the basic model based on the working conditions of each stage, and obtaining the contact structure of each stage by fitting the minimum discrete unit; Step 8: Import the contact structures at each stage of fitting into the finite element model and run simulation to obtain the temperature distribution law in order to analyze the temperature rise characteristics.

2. According to claim 1, a temperature rise modeling method for an environmental protection cabinet that dynamically reflects the microscopic changes in the contact structure is characterized by: The environmental protection cabinet consists of an operating mechanism room, a cable room, a busbar room, an instrument room and a pressure relief room; the busbar room is sealed by a gas box and maintains a slight positive pressure of 0.3Mpa. The busbar room contains a three-phase busbar, a circuit breaker, an isolating knife switch, an insulating bushing and a fixed partition.

3. The method for modeling temperature rise of an environmental protection cabinet that dynamically reflects microscopic changes in contact structure according to claim 1 is characterized in that: In step 2, mathematical software is used to calculate the electrical wear parameters of the Baharami electrical contact model.

4. The method for modeling temperature rise of an environmental protection cabinet that dynamically reflects microscopic changes in contact structure according to claim 1 is characterized in that: The formula for calculating the electrical wear parameters of the Baharami electrical contact model in step 2 is as follows: n s =1 / 16(σ / m) 2 [exp(-2λ 2 ) / (e rfc l)]A (4) Where ρ represents the resistivity of the contact material; a s Indicates the radius of the bulge; n s represents the number of protrusions in the discrete unit; λ represents the contact gap characteristic function; γ represents the equivalent distance between the center line of the rigid sphere and the elastic rough surface and the smooth rigid surface of the discrete unit; σ represents the equivalent roughness; e rfc represents the Gaussian error function; A represents the nominal contact area; m represents the slope of the tiny contact point on the contact along the section.

5. The method for modeling temperature rise of an environmental protection cabinet that dynamically reflects microscopic changes in contact structure according to claim 1 is characterized in that: In step 4, the rated current of the environmental protection cabinet is 630A, and the temperature rise test is carried out at 1.1 times the rated current; the operating environment temperature is set to room temperature, that is, 298.15K.

6. The method for modeling temperature rise of an environmental protection cabinet that dynamically reflects microscopic changes in contact structure according to claim 1 is characterized in that: The surface structure parameters in step 7 include the coarse-grainedness, the number of contact micro-humps, and the radius.

7. The method for modeling temperature rise of an environmental protection cabinet that dynamically reflects microscopic changes in contact structure according to claim 1 is characterized in that: In step 7, by investigating the same type of environmental protection cabinets with different service periods, the distribution characteristics of convex hills in different wear states are measured, and this is used as a reference value to set the parameters of the temperature rise model to simulate different working conditions of the equipment.

Images