Switch cabinet partial discharge simulation method and system

Abstract

The invention provides a switch cabinet partial discharge simulation method and system, and relates to the technical field of high voltage and insulation, and the method comprises the steps: obtaining the geometric dimension parameters of a switch cabinet, and constructing a switch cabinet simulation grid model; acquiring material data of the switch cabinet, and fitting a curve of material parameters changing along with temperature; performing electromagnetic simulation on the switch cabinet to obtain distribution of a temperature field and a flow field in the switch cabinet; and performing grid data mapping, and coupling the grid data to the switch cabinet simulation grid model. According to the method, the technical problem that in the prior art, due to the fact that nonlinear changes of material parameters along with the temperature and the electrothermal coupling relation are not considered, large deviation exists between the simulation result and the actual operation condition can be solved; and a curve of material parameters changing along with the temperature is mapped, so that a more accurate simulation result is realized, and the stability and the safety of the operation of the switch cabinet are improved.

Description

Technical Field

[0001] The present application relates to the field of high voltage and insulation technology, and in particular to a method and system for simulating partial discharge of a switch cabinet. Background Art

[0002] With the continuous expansion of the scale of power grids and the continuous improvement of voltage levels, switchgear, as an important equipment in the power system, has very complex operating conditions. In order to ensure the safe and stable operation of switchgear, it is particularly important to use simulation methods to conduct comprehensive research on it. However, existing simulation methods have certain limitations in dealing with the problem of partial discharge in switchgear. The operating environment of the switchgear is complex, and the insulating medium of the switchgear often has defects such as air gaps, impurities, and spikes. Since the dielectric constant of the defective part is relatively small, the electric field strength of the defective part is large under the action of the applied voltage. When the electric field of the defective part exceeds the defect breakdown electric field, partial discharge will occur, which may lead to irreversible degradation of the insulation system. Existing simulation technologies often fail to fully consider these complex factors. Especially in terms of multi-physical field coupling, the temperature field and the electric field are usually not effectively coupled in the existing technology. Most simulations only rely on the law of change of material parameters with temperature to simulate the electric field distribution at a specific temperature, while ignoring the nonlinear relationship between material parameters such as conductivity and relative dielectric constant and the electric field. This processing method breaks the coupling relationship of electrothermal mapping, resulting in a large deviation between the simulation results and the actual situation.

[0003] In summary, the prior art has a technical problem in that the nonlinear variation of material parameters with temperature and the electrothermal coupling relationship are not considered, resulting in a large deviation between the simulation results and the actual operating conditions. Summary of the invention

[0004] The purpose of this application is to provide a switch cabinet partial discharge simulation method and system to solve the technical problem in the prior art that the simulation results have a large deviation from the actual operating conditions due to the failure to consider the nonlinear changes of material parameters with temperature and the electrothermal coupling relationship.

[0005] In view of the above problems, the present application provides a switch cabinet partial discharge simulation method and system.

[0006] In a first aspect, the present application provides a switch cabinet partial discharge simulation method, which is implemented by a switch cabinet partial discharge simulation system, wherein the switch cabinet partial discharge simulation method includes: obtaining geometric dimension parameters of the switch cabinet and constructing a switch cabinet simulation grid model; obtaining switch cabinet material data, the switch cabinet material data is experimental data of relevant materials on the switch cabinet at different temperatures, and fitting a material parameter temperature variation curve according to the switch cabinet material data; performing electromagnetic simulation on the switch cabinet, calculating the heat source of the switch cabinet, and obtaining the temperature field and flow field distribution inside the switch cabinet; performing grid data mapping on the material parameter temperature variation curve, the temperature field and flow field distribution inside the switch cabinet, and coupling them to the switch cabinet simulation grid model.

[0007] In the second aspect, the present application also provides a switch cabinet partial discharge simulation system, which is used to execute a switch cabinet partial discharge simulation method as described in the first aspect, wherein the switch cabinet partial discharge simulation system includes: a parameter acquisition module, the parameter acquisition module is used to acquire the geometric size parameters of the switch cabinet and construct a switch cabinet simulation grid model; a data acquisition module, the data acquisition module is used to acquire the switch cabinet material data, the switch cabinet material data is the experimental data of the relevant materials on the switch cabinet at different temperatures, and the material parameter temperature variation curve is fitted according to the switch cabinet material data; an electromagnetic simulation module, the electromagnetic simulation module is used to perform electromagnetic simulation on the switch cabinet, calculate the heat source of the switch cabinet, and obtain the temperature field and flow field distribution inside the switch cabinet; a data coupling module, the data coupling module is used to perform grid data mapping on the material parameter temperature variation curve, the temperature field and flow field distribution inside the switch cabinet, and couple them to the switch cabinet simulation grid model.

[0008] One or more technical solutions provided in this application have at least the following technical effects or advantages:

[0009] By acquiring the geometric size parameters of the switch cabinet, a switch cabinet simulation grid model is constructed; the switch cabinet material data is acquired, and the switch cabinet material data is the experimental data of the relevant materials on the switch cabinet at different temperatures, and the material parameter temperature variation curve is fitted according to the switch cabinet material data; the switch cabinet is subjected to electromagnetic simulation, the heat source of the switch cabinet is calculated, and the temperature field and flow field distribution inside the switch cabinet are obtained; the material parameter temperature variation curve, the temperature field and flow field distribution inside the switch cabinet are mapped to the grid data, and coupled to the switch cabinet simulation grid model. In other words, by constructing a simulation grid model that considers the coupling of temperature field, flow field and electric field, and mapping the material parameter temperature variation curve, a more accurate simulation result is achieved, and the stability and safety of the switch cabinet operation are improved.

[0010] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented according to the contents of the specification, and in order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are specifically cited below. It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present application, nor is it intended to limit the scope of the present application. Other features of the present application will become easy to understand through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions in the present application or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0012] Figure 1 A schematic diagram of a flow chart of a partial discharge simulation method for a switch cabinet according to the present application;

[0013] Figure 2 A schematic diagram of a flow chart of obtaining the temperature field and flow field distribution inside a switch cabinet in a switch cabinet partial discharge simulation method of the present application;

[0014] Figure 3 This is a structural schematic diagram of a switch cabinet partial discharge simulation system according to the present application.

[0015] Description of reference numerals: parameter acquisition module 11 , data acquisition module 12 , electromagnetic simulation module 13 , data coupling module 14 . DETAILED DESCRIPTION

[0016] This application provides a switch cabinet partial discharge simulation method and system to solve the technical problem in the prior art that the simulation results are significantly different from the actual operation due to the failure to consider the nonlinear change of material parameters with temperature and the electrothermal coupling relationship. By constructing a simulation grid model that considers the coupling of temperature field, flow field and electric field, and mapping the curve of material parameters changing with temperature, more accurate simulation results are achieved, and the stability and safety of switch cabinet operation are improved.

[0017] Below, the technical solutions in the present application will be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments of the present application. It should be understood that the present application is not limited to the example embodiments described herein. Based on the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application. It should also be noted that, for the convenience of description, only the parts related to the present application are shown in the accompanying drawings, rather than all of them.

[0018] For example, please refer to the attached Figure 1 The present application provides a switch cabinet partial discharge simulation method, wherein the switch cabinet partial discharge simulation method is applied to a switch cabinet partial discharge simulation system, and the switch cabinet partial discharge simulation method specifically includes the following steps:

[0019] Step 1: Obtain the geometric dimension parameters of the switch cabinet and build a switch cabinet simulation grid model.

[0020] Specifically, the detailed design drawings and technical documents of the switch cabinet are collected, which are usually provided by the designer or manufacturer of the switch cabinet, including the size, shape and relative position of each component of the switch cabinet. These data are the basis for building the simulation model. The geometric dimension parameters include but are not limited to length, width, height, aperture size, component spacing, etc., which determine the structure and layout of the internal space of the switch cabinet. According to the geometric dimension parameters, the geometric model of the switch cabinet is constructed using CAD software to ensure that the model includes all key components of the switch cabinet, such as busbars, circuit breakers, insulators, contact boxes, support structures, etc. The COMSOL software is used to perform the initial triangulation of the switch cabinet geometric model, and then the key parts such as contact boxes, busbars and other structures are ultra-finely divided. After meshing, the mesh quality is checked to ensure that there are no overly distorted elements and the connectivity of the mesh is good. Through the collaborative call of the mesh modeling interface between MATLAB and COMSOL, the simulation mesh model of the switch cabinet is quickly and efficiently established using programming language. By constructing an accurate simulation mesh model, the accuracy and reliability of the simulation analysis are significantly improved.

[0021] Step 2: Obtain switch cabinet material data, which is experimental data of relevant materials on the switch cabinet at different temperatures, and fit a curve of material parameter variation with temperature based on the switch cabinet material data.

[0022] Specifically, data on relevant materials on the switchgear, including insulating materials, conductive materials, and heat dissipation materials, are collected from material suppliers, relevant standard documents, or internal tests. The required data types, such as conductivity, relative dielectric constant, thermal conductivity, and thermal expansion coefficient, are clarified. Material data directly affects the performance of the switchgear under actual working conditions. For example, the dielectric constant of the insulating material affects the distribution of the electric field, while the thermal conductivity affects the heat dissipation performance of the switchgear. Test the material samples at a set temperature and record the data. Test the material at a series of temperatures to obtain its performance parameters at different temperatures, such as the variation of conductivity, relative dielectric constant, etc. with temperature. Obtain the values ​​of relative dielectric constant and conductivity of the copper conductor and insulating partition inside the switchgear at different temperatures, and obtain the functional relationship of the relative dielectric constant and conductivity with temperature through least squares fitting. Obtain the experimental data of the switchgear materials at different temperatures, and obtain the curve of the material parameters changing with temperature through curve fitting to understand the performance of the switchgear under actual working conditions.

[0023] Step 3: Perform electromagnetic simulation on the switch cabinet, calculate the heat source of the switch cabinet, and obtain the temperature field and flow field distribution inside the switch cabinet.

[0024] Specifically, by calling the electromagnetic simulation module, the loss separation model is used to solve the losses of current-carrying conductors such as various busbars, circuit breaker dynamic / static ends and contacts, disconnector contact seats and contact fingers. Electromagnetic simulation is a method that uses computer simulation technology to analyze the electromagnetic field distribution, current flow and voltage distribution in circuits or equipment. In the design and analysis of switch cabinets, electromagnetic simulation is used to simulate the working conditions of the internal circuits of switch cabinets, including the flow of current, the distribution of voltage, the generation of magnetic fields, etc. At the same time, the hysteresis loss and eddy current loss of the magnetic materials of the switch cabinet at the fundamental frequency are solved respectively, and the loss of the switch cabinet under non-sinusoidal current is considered. The correction method of the influence of high-order harmonics on the loss in the latest standard is adopted. The heat source of the switch cabinet refers to the heat generated inside the switch cabinet, which mainly comes from the Joule heat generated when the current passes through the conductor, the mechanical loss during the switch operation, and the resistance loss of the internal components of the switch cabinet. The heat source inside the switch cabinet will have an important impact on the performance of the switch cabinet, such as causing material aging, reduced insulation performance, and even fire. The electromagnetic heat generated by the switch cabinet is used as the heat source of temperature-flow field coupling. The temperature field and flow field distribution inside the switch cabinet are obtained through thermal fluid dynamics analysis. The temperature field and flow field distribution reflect the heat distribution inside the switch cabinet, which is crucial for evaluating the thermal performance and heat dissipation design of the switch cabinet. Calculating the heat source of the switch cabinet through electromagnetic simulation and obtaining the temperature field and flow field distribution inside the switch cabinet help understand and optimize the performance of the switch cabinet.

[0025] Step 4: Map the material parameter versus temperature curve, the temperature field and flow field distribution inside the switch cabinet to grid data, and couple them to the switch cabinet simulation grid model.

[0026] Specifically, the curves of material parameters changing with temperature obtained by experiment and least squares fitting are mapped to grid data, that is, the temperature dependence of material parameters is applied to each node of the switch cabinet simulation grid to ensure that each node has corresponding material properties. The temperature field and flow field distribution data are obtained through electromagnetic simulation and thermal analysis, and mapped to the simulation grid model of the switch cabinet, that is, the temperature and velocity distribution information calculated in the simulation is applied to the grid model of the switch cabinet, so that the model can reflect the thermal and fluid dynamics behavior under actual working conditions. The data is transferred through the node mapping method, and the simulation results of the temperature field-flow field and the nonlinear relationship curve of the switch cabinet material properties are transferred to the electric field simulation calculation grid through the interpolation method to achieve deep electrothermal coupling. Through this coupling, a more comprehensive and accurate simulation analysis of the switch cabinet can be carried out, so that the simulation model can simultaneously consider the heat transfer and fluid flow inside the switch cabinet, thereby more accurately simulating the overall performance of the switch cabinet.

[0027] Furthermore, step one of this application includes:

[0028] According to the geometric size parameters, a geometric model of the switch cabinet is constructed; a triangular mesh is selected for the model network of the geometric model to perform mesh division; a mesh modeling interface is collaboratively called through MATLAB and COMSOL, and a simulation mesh model of the switch cabinet is constructed based on the mesh division result.

[0029] Specifically, a 3D model is drawn using professional computer-aided design (CAD) software based on the collected geometric dimension parameters. Each component of the switchgear is drawn in the CAD software, including the housing, internal brackets, insulation materials, conductors, etc. These components are assembled according to their actual relative positions to form a complete switchgear geometric model. The entire geometric model is initially triangular meshed to create a basic mesh structure covering the entire model. Multiple ultra-fine meshes are performed for key boundaries and areas in the model, such as areas where partial discharge may occur and areas with significant temperature changes, to ensure that the mesh density in these areas is high enough. Check the mesh quality to ensure that there are no overly distorted elements, and optimize the mesh if necessary. The triangular mesh is a mesh system composed of many small triangular elements, which has good flexibility and can better adapt to complex geometric shapes. Each triangular element has nodes, which are the basic components of the mesh. The density and size of the mesh depend on the requirements of the simulation and the limitations of computing resources.

[0030] Ultra-fine meshing refers to the use of smaller and denser mesh elements in these key areas to more accurately capture the physical phenomena in these areas. In COMSOL, the modeling function is used to perform preliminary triangular meshing on the switch cabinet model. In order to make the complex structure and multi-physical field distribution more in line with the actual working conditions, ultra-fine meshing is performed on key parts such as contact boxes, busbars and other structures. In COMSOL, boundary conditions refer to the physical conditions on the set model boundaries, such as heat dissipation boundaries in temperature fields and flow fields, insulation boundaries in electric fields, etc., which are crucial to the accuracy of simulation results. Boundary conditions include first-class boundary conditions and second-class boundary conditions, which refer to the specific values ​​of physical quantities given on the boundaries (first-class boundary conditions) and the values ​​of the derivatives of physical quantities given on the boundaries (second-class boundary conditions).

[0031] Use JAVA language to program the program commands of MATLAB control files, and draw the switch cabinet geometry model through MATLAB control to achieve fast and accurate model establishment. Combined with the COMSOL Multiphysics with MATLAB coordination software interface, the data processing capabilities in MATLAB and the multi-physics simulation function of COMSOL are combined to achieve precise control of the switch cabinet model. Based on the mesh generation results, the switch cabinet simulation mesh model is constructed in COMSOL. Combining the data processing capabilities of MATLAB and the multi-physics simulation function of COMSOL, the automatic establishment of the model and the targeted mesh generation are realized through programming, which improves the accuracy and efficiency of the simulation.

[0032] Furthermore, the present application also includes the following steps:

[0033] Using triangular meshes for initial segmentation; setting key boundaries and key areas, wherein the key boundaries include heat dissipation boundaries and insulation boundaries, and the key areas include switch cabinet component structural positions; and performing detailed segmentation on the key boundaries and key areas.

[0034] Specifically, a triangular mesh type is selected in the meshing software because triangular meshes can better adapt to complex geometric shapes and are easy to refine locally. According to the overall size of the switchgear and the expected simulation accuracy, the size of the global mesh is set, which is usually an estimate to control the density of the mesh. The switchgear model is initially divided into triangles using the modeling function of the COMSOL software. Key boundaries include heat dissipation boundaries in the temperature field-flow field and insulation boundaries in the electric field. Key areas include the structural positions of switchgear components, such as contact boxes, busbars, insulators, etc. The changes in the electric field and temperature field in these areas may be more complex, so special attention should be paid to using more detailed meshes to capture their physical properties. The identified key boundaries and areas are ultra-finely divided, such as reducing the mesh size, increasing the mesh density, etc., to improve the mesh density and simulation accuracy. Through refined division, the accuracy of the switchgear simulation mesh model in key areas is significantly improved, making the simulation results more in line with actual working conditions.

[0035] Further, step 2 of this application includes:

[0036] The relative dielectric constant and conductivity values ​​of the internal conductor and insulating partition of the switch cabinet at different temperatures are obtained; the nonlinear functional relationship between the relative dielectric constant and the conductivity value and the temperature is fitted by the least squares method to obtain the curve of the material parameter changing with temperature.

[0037] Specifically, the relative dielectric constant and conductivity values ​​of the internal conductors and insulating partitions of the switch cabinet at different temperatures are collected. They are obtained through experiments. Different temperature points are set in the experiment to cover the operating temperature range of the switch cabinet, and a series of test results at different temperatures are obtained. The relative dielectric constant is a key parameter for measuring the performance of insulating materials, which affects the electric field distribution and insulation strength. Conductivity is a key parameter for measuring the performance of conductor materials, which affects current flow and heat loss. Check and remove abnormal data points, and organize the data into a format suitable for least squares fitting. The least squares method is used to fit the nonlinear functional relationship between these parameters and temperature. The least squares method is a statistical method used to find the best function match for data by minimizing the sum of squares of errors. Through the least squares method, the curves of these material parameters changing with temperature are obtained, reflecting the trend of material performance changing with temperature. For example, the relative dielectric constant and conductivity of the copper conductor and insulating partition inside the switch cabinet at different temperatures are obtained, and then the least square method or other statistical methods are used to determine the best fitting curve, and the functional relationship between the relative dielectric constant and conductivity and temperature is obtained as follows: The relationship between the relative dielectric constant of the copper conductor and the temperature is: 2.710-0.002T-3.124×10 -8 T 3 , where T represents temperature, indicating that the relative dielectric constant decreases nonlinearly with temperature; the relationship between conductivity and temperature is: -3.989×10-13 -10 -17 T 2 +2×10 -19 T 3 , which indicates that the conductivity of copper conductor increases with the increase of temperature T. The relationship between the relative dielectric constant of the insulating separator and the temperature is: 2.796e 0.00209T , which characterizes that the relative dielectric constant of the insulating separator is very sensitive to temperature and increases sharply with the increase of temperature; the relationship between the change of conductivity and temperature is: 3.014×10 -44 T 11.064 , which indicates that the conductivity of the insulating partition increases with the increase of temperature T. By taking the relative dielectric constant and conductivity values ​​of the internal conductor and insulating partition of the switch cabinet at different temperatures, and fitting the nonlinear functional relationship between these parameters and temperature by the least squares method, the curve of material parameters changing with temperature is obtained, which helps to improve the accuracy and reliability of the simulation model.

[0038] Further, step three of this application includes:

[0039] The loss separation model is used to solve the switch cabinet loss, which includes: the loss of each current-carrying conductor and the loss of the magnetic material of the switch cabinet at the fundamental frequency; the loss of the magnetic material under non-sinusoidal current is calculated by using the correction method for the influence of high-order harmonics on the loss; the temperature field and flow field simulation is performed based on the loss to determine the electromagnetic heat generated by the switch cabinet as the heat source of temperature-flow field coupling, and the temperature field and flow field distribution inside the switch cabinet are obtained.

[0040] Specifically, the electromagnetic simulation module is called, and the loss separation model is used to solve the switch cabinet loss. The switch cabinet loss includes: the loss of each current-carrying conductor and the loss of the switch cabinet magnetic material at the fundamental frequency. The loss of each current-carrying conductor includes the loss of various busbars, circuit breaker dynamic / static ends and contacts, disconnector contact seats and contact fingers and other current-carrying conductors. The loss of the switch cabinet magnetic material at the fundamental frequency refers to the hysteresis loss and eddy current loss generated when the magnetic materials (such as ferromagnetic materials) used in the switch cabinet work in an alternating magnetic field. These losses are caused by the magnetization of the magnetic material and the flow of current. The correction method for the influence of high-order harmonics on losses in the latest standard is used to calculate the loss of magnetic materials under non-sinusoidal current. Current is usually non-sinusoidal and contains harmonic components of various frequencies. These high-order harmonics will affect the performance of the equipment, including increasing losses.

[0041] The purpose of temperature field and flow field simulation is to simulate the heat distribution inside the switch cabinet, predict the temperature changes of the switch cabinet under different working conditions, and evaluate its heat dissipation performance and potential thermal management issues. The electromagnetic heat generated by the switch cabinet is used as the heat source for temperature-flow field coupling, that is, the loss in the electromagnetic simulation will be converted into thermal energy, affecting the temperature distribution of the switch cabinet. Through simulation, the temperature field and flow field distribution inside the switch cabinet are obtained, and the one-way coupling of the electric field to the temperature-flow field is realized, that is, the electric field affects the temperature field and flow field, but the temperature field and flow field do not affect the electric field.

[0042] In a possible example, as shown in the attached Figure 2 As shown, the switch cabinet losses are calculated, including the losses of each current-carrying conductor and the losses of the switch cabinet magnetic materials at the fundamental frequency. The temperature field and flow field simulation calculations are performed, considering the air flow and temperature distribution inside the switch cabinet, understanding the heat exchange process inside the switch cabinet, and how it affects the thermal performance of the switch cabinet. ΔT n +1≤ε is a conditional judgment, ΔT n +1 indicates the temperature difference between the current iteration step and the previous iteration step, and ε is a preset convergence threshold. When the temperature difference is greater than ε, it means that there is a deviation between the simulation result and the actual situation, and a correction loss calculation is required. When the temperature difference is less than or equal to ε, it means that the simulation result is consistent with the actual situation, and the temperature-flow field distribution of the switch cabinet is continued to be calculated, and the temperature field and flow field simulation results are combined to reflect the thermal and fluid dynamics behavior inside the switch cabinet. Next, the simulation results of the temperature field-flow field and the nonlinear relationship curve of the switch cabinet material properties are transferred to the electric field simulation calculation grid using the interpolation method. In this process, it is necessary to consider the nonlinear changes of the insulation material parameters with temperature, including the characteristics of the dielectric constant, thermal conductivity and other parameters with temperature. Calculate the electric field distribution of the switch cabinet and evaluate the distribution of the electric field inside the switch cabinet. Finally, the process ends. Through this process, the temperature field-flow field simulation of the switch cabinet is realized, and the nonlinear changes of material parameters are considered, thereby improving the accuracy of the simulation results.

[0043] By considering the influence of high-order harmonics and truly simulating the losses under actual working conditions, the temperature field and flow field simulation based on the losses predicts the thermal performance of the switchgear in actual operation, including temperature distribution and heat flow, which helps to evaluate its heat dissipation performance and potential thermal management issues.

[0044] Furthermore, the present application also includes the following steps:

[0045] Through the current-carrying conductor loss formula: P = K h f α B β +K e (fB) 2 , calculate the loss of each current-carrying conductor, where B is a function of the magnetic flux density and the coefficient K ish , K e , a and b are obtained by fitting the loss curve data, K e (fB) 2 is the eddy current loss, K h f α B β It is the sum of hysteresis loss and abnormal loss; when high-order harmonics are contained, the eddy current loss under distorted magnetic flux Among them, σ is the conductivity of the current-carrying conductor, NH is the highest harmonic order, B h is the amplitude of the hth harmonic; the loss of the switchgear magnetic material at the fundamental frequency is calculated by the hysteresis loss formula and eddy current loss formula of the magnetic material, where the hysteresis loss formula of the magnetic material is: The formula for eddy current loss is: Among them, k h =I h / I l is the ratio of the hth harmonic current to the effective value of the fundamental current, P WR is the hysteresis loss of the magnetic material under fundamental wave conditions, P WEI is the eddy current loss of the magnetic material at the fundamental frequency, h = f h / f l It is the ratio of the hth harmonic current frequency to the fundamental current frequency.

[0046] Specifically, the loss separation model solves the current-carrying conductor loss including hysteresis loss, eddy current loss and abnormal loss. Hysteresis loss is the energy loss caused by the nonlinearity of the material magnetization process, eddy current loss is the energy loss caused by the change of the internal current of the material with the magnetic field, and abnormal loss includes the energy loss caused by the non-uniform distribution of the electric field and magnetic field. These losses are caused by the magnetization of the magnetic material in the alternating magnetic field and the flow of current. Through the current-carrying conductor loss formula P = K h f α B β +K e (fB) 2 , calculate the loss of each current-carrying conductor, including hysteresis loss, abnormal loss, and eddy current loss. K e 9fB) 2 is the eddy current loss, K h f α B β is the sum of hysteresis loss and abnormal loss. B is a function of magnetic flux density, coefficient K h , K e , a and b are obtained by fitting the loss curve data.

[0047] When the current contains high-order harmonics, the eddy current loss will change. Calculate the eddy current loss under distorted magnetic flux, where σ is the conductivity of the current-carrying conductor, NH is the highest harmonic order, and B h is the amplitude of the hth harmonic.

[0048] Solving the switchgear magnetic material loss includes: When solving the switchgear magnetic material loss, the hysteresis loss and eddy current loss of the magnetic material are solved separately. The hysteresis loss is caused by the conversion of energy during the magnetization and demagnetization process of the magnetic material in the alternating magnetic field, while the eddy current loss is the heat generated by the flow of current inside the magnetic material. The hysteresis loss formula of the magnetic material under harmonic conditions is: P R is the total hysteresis loss of the magnetic material, k h =I h / I l is the ratio of the hth harmonic current to the effective value of the fundamental current, P WR is the hysteresis loss of the magnetic material under fundamental wave conditions, and NH is the highest harmonic order. The formula for the eddy current loss of the switchgear magnetic material under harmonic conditions is: Among them, P E is the eddy current loss of the magnetic material, P WEI is the eddy current loss of the magnetic material at the fundamental frequency, P WE It is the eddy current loss caused by the current waveform distortion under harmonic conditions, h = f h / f l It is the ratio of the hth harmonic current frequency to the fundamental current frequency.

[0049] Furthermore, the present application also includes the following steps:

[0050] The electromagnetic heat generated by the switch cabinet is used as the heat source of the temperature-flow field. The heat dissipation inside the switch cabinet is achieved through air convection. The entire heat dissipation process satisfies the conservation of mass, momentum and energy. The temperature-flow field coupling simulation is performed based on the conservation equation, where the conservation equation is: in, is the temperature, λ and S are the diffusion coefficient term and the generalized source term respectively, ρ is the air density, and v and u are the velocity vectors in the x and y directions respectively.

[0051] Specifically, temperature-flow field coupling simulation is a method to simulate the heat transfer and flow inside an object, which is the interaction between heat and fluid dynamics. The electromagnetic heat generated by the switch cabinet is used as the heat source of the temperature-flow field. This heat is converted from the loss generated when the current passes through the conductor and the magnetic material. The switch cabinet dissipates heat through air convection. The air flow inside the switch cabinet takes away the heat, thereby reducing the temperature. The entire heat dissipation process satisfies the conservation of mass, momentum and energy, and the corresponding conservation equation is the general equation: in, is the temperature; λ is the diffusion coefficient term, which represents the ability of heat to spread in the material; S is the generalized source term, which represents other heat sources or heat sinks besides heat transfer; ρ is the air density, which affects the heat transfer; v and u are the velocity vectors in the x and y directions, respectively, which affect the air flow and heat transfer.

[0052] Further, step 4 of this application includes:

[0053] The material parameter variation curve with temperature, the temperature field and flow field distribution inside the switch cabinet are transferred to the electric field simulation calculation grid through the interpolation method.

[0054] Specifically, the temperature field and flow field distribution data obtained by electromagnetic simulation and thermal analysis are mapped to the switchgear simulation grid model, and the temperature and velocity distribution information calculated in the simulation is applied to the switchgear grid model, so that the model can reflect the thermal and fluid dynamics behavior under actual working conditions. The key data in the temperature field-flow field simulation results are transferred to the electric field simulation calculation grid using the node mapping method. The node mapping method is a data transfer technology that allows data on one grid to be mapped to another grid, thereby realizing data sharing and interaction between different simulation models. The nonlinear relationship curve of the switchgear material properties is transferred to the electric field simulation calculation grid through the interpolation method. The interpolation method is used to estimate unknown data values ​​between known data points, so as to realize the accurate representation of the nonlinear relationship of material properties with temperature changes in the electric field simulation calculation grid. Through the application of this data mapping and interpolation method, the deep electrothermal coupling simulation of the switchgear is realized. Deep electrothermal coupling means that the electric field simulation can consider the thermal effects inside the switchgear, while the thermal analysis can consider the heat source generated by the electric field, which helps to more accurately simulate the overall performance of the switchgear under actual working conditions. The existence of the temperature gradient inside the switch cabinet will inevitably lead to nonlinear changes in the material properties of the switch cabinet conductor and the insulating partition. Bidirectional coupling means that the current and voltage in the electric field simulation will affect the temperature field and flow field, and the temperature field and flow field will in turn affect the current and voltage in the electric field simulation. Exemplarily, when setting the parameters of each material in the COMSOL software, the nonlinear relationship expression of the material is input into the software, and the COMSOL software will iteratively calculate by itself to obtain the temperature field-flow field distribution considering the nonlinearity of the material. First, the temperature field-flow field distribution is calculated, and this calculation is used as the first step of the multi-field coupling calculation, and the electric field distribution is calculated in the second step. The research steps are set in the COMSOL software, and the settings are performed in the COMSOL software according to the above process to realize the transfer of results and achieve deep coupling. The material parameter temperature change curve, temperature field and flow field distribution are transferred to the electric field simulation calculation grid by interpolation method to achieve accurate electric field simulation and improve the accuracy and reliability of the simulation results.

[0055] In summary, the switch cabinet partial discharge simulation method provided by the present application has the following technical effects:

[0056] By acquiring the geometric size parameters of the switch cabinet, a switch cabinet simulation grid model is constructed; the switch cabinet material data is acquired, and the switch cabinet material data is the experimental data of the relevant materials on the switch cabinet at different temperatures, and the material parameter temperature variation curve is fitted according to the switch cabinet material data; the switch cabinet is subjected to electromagnetic simulation, the heat source of the switch cabinet is calculated, and the temperature field and flow field distribution inside the switch cabinet are obtained; the material parameter temperature variation curve, the temperature field and flow field distribution inside the switch cabinet are mapped to the grid data, and coupled to the switch cabinet simulation grid model. In other words, by constructing a simulation grid model that considers the coupling of temperature field, flow field and electric field, and mapping the material parameter temperature variation curve, a more accurate simulation result is achieved, and the stability and safety of the switch cabinet operation are improved.

[0057] Embodiment 2: Based on the same inventive concept as the switch cabinet partial discharge simulation method in the above embodiment, the present application also provides a switch cabinet partial discharge simulation system, please refer to the attached Figure 3 , the switch cabinet partial discharge simulation system comprises:

[0058] The parameter acquisition module 11 is used to acquire the geometric size parameters of the switch cabinet and construct a switch cabinet simulation grid model.

[0059] The data acquisition module 12 is used to acquire switch cabinet material data, wherein the switch cabinet material data is experimental data of relevant materials on the switch cabinet at different temperatures, and a material parameter temperature variation curve is fitted according to the switch cabinet material data.

[0060] The electromagnetic simulation module 13 is used to perform electromagnetic simulation on the switch cabinet, calculate the heat source of the switch cabinet, and obtain the temperature field and flow field distribution inside the switch cabinet.

[0061] The data coupling module 14 is used to map the material parameter temperature variation curve, the temperature field and flow field distribution inside the switch cabinet to grid data, and couple them to the switch cabinet simulation grid model.

[0062] Furthermore, the parameter acquisition module 11 in the switch cabinet partial discharge simulation system is also used for:

[0063] According to the geometric size parameters, a geometric model of the switch cabinet is constructed; a triangular mesh is selected for the model network of the geometric model to perform mesh division; a mesh modeling interface is collaboratively called through MATLAB and COMSOL, and a simulation mesh model of the switch cabinet is constructed based on the mesh division result.

[0064] Furthermore, the switch cabinet partial discharge simulation system further includes a grid generation module, which is used to:

[0065] Using triangular meshes for initial segmentation; setting key boundaries and key areas, wherein the key boundaries include heat dissipation boundaries and insulation boundaries, and the key areas include switch cabinet component structural positions; and performing detailed segmentation on the key boundaries and key areas.

[0066] Furthermore, the data acquisition module 12 in the switch cabinet partial discharge simulation system is also used for:

[0067] The relative dielectric constant and conductivity values ​​of the internal conductor and insulating partition of the switch cabinet at different temperatures are obtained; the nonlinear functional relationship between the relative dielectric constant and the conductivity value and the temperature is fitted by the least squares method to obtain the curve of the material parameter changing with temperature.

[0068] Furthermore, the electromagnetic simulation module 13 in the switch cabinet partial discharge simulation system is also used for:

[0069] The loss separation model is used to solve the switch cabinet loss, which includes: the loss of each current-carrying conductor and the loss of the magnetic material of the switch cabinet at the fundamental frequency; the loss of the magnetic material under non-sinusoidal current is calculated by using the correction method for the influence of high-order harmonics on the loss; the temperature field and flow field simulation is performed based on the loss to determine the electromagnetic heat generated by the switch cabinet as the heat source of temperature-flow field coupling, and the temperature field and flow field distribution inside the switch cabinet are obtained.

[0070] Furthermore, the switch cabinet partial discharge simulation system further includes a loss solving module, which is used to:

[0071] Through the current-carrying conductor loss formula: P = K h f α B β +K e (fB) 2 , calculate the loss of each current-carrying conductor, where B is a function of the magnetic flux density and the coefficient K is h , K e , a and b are obtained by fitting the loss curve data, K e (fB) 2 is the eddy current loss, K h f α B β It is the sum of hysteresis loss and abnormal loss; when high-order harmonics are contained, the eddy current loss under distorted magnetic flux Among them, σ is the conductivity of the current-carrying conductor, NH is the highest harmonic order, B his the amplitude of the hth harmonic; the loss of the switchgear magnetic material at the fundamental frequency is calculated by the hysteresis loss formula and eddy current loss formula of the magnetic material, where the hysteresis loss formula of the magnetic material is: The formula for eddy current loss is: Among them, k h =I h / I l is the ratio of the hth harmonic current to the effective value of the fundamental current, P WR is the hysteresis loss of the magnetic material under fundamental wave conditions, P WEI is the eddy current loss of the magnetic material at the fundamental frequency, h = f h / f l It is the ratio of the hth harmonic current frequency to the fundamental current frequency.

[0072] Furthermore, the switch cabinet partial discharge simulation system further includes a simulation module, which is used to:

[0073] The electromagnetic heat generated by the switch cabinet is used as the heat source of the temperature-flow field. The heat dissipation inside the switch cabinet is achieved through air convection. The entire heat dissipation process satisfies the conservation of mass, momentum and energy. The temperature-flow field coupling simulation is performed based on the conservation equation, where the conservation equation is: in, is the temperature, λ and S are the diffusion coefficient term and the generalized source term respectively, ρ is the air density, and v and u are the velocity vectors in the x and y directions respectively.

[0074] Furthermore, the data coupling module 14 in the switch cabinet partial discharge simulation system is also used for:

[0075] The material parameter variation curve with temperature, the temperature field and flow field distribution inside the switch cabinet are transferred to the electric field simulation calculation grid through the interpolation method.

[0076] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. Figure 1 The switch cabinet partial discharge simulation method and specific examples in the first embodiment are also applicable to the switch cabinet partial discharge simulation system in the present embodiment. Through the above detailed description of the switch cabinet partial discharge simulation method, those skilled in the art can clearly know the switch cabinet partial discharge simulation system in the present embodiment, so for the sake of brevity of the specification, it will not be described in detail here. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0077] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

[0078] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application belong to the scope of the present application and its equivalent technology, the present application is also intended to include these modifications and variations.

Claims

1. A switch cabinet partial discharge simulation method, characterized in that: The switch cabinet partial discharge simulation method comprises: Obtain the geometric size parameters of the switch cabinet and build a simulation grid model of the switch cabinet; Acquire switch cabinet material data, wherein the switch cabinet material data is experimental data of relevant materials on the switch cabinet at different temperatures, and fit a curve of material parameter variation with temperature according to the switch cabinet material data; Perform electromagnetic simulation on the switch cabinet, calculate the heat source of the switch cabinet, and obtain the temperature field and flow field distribution inside the switch cabinet; The material parameter temperature variation curve, the temperature field and flow field distribution inside the switch cabinet are subjected to grid data mapping and coupled to the switch cabinet simulation grid model.

2. A switch cabinet partial discharge simulation method according to claim 1, characterized in that: The step of obtaining geometric dimension parameters of the switch cabinet and constructing a switch cabinet simulation grid model includes: Constructing a geometric model of the switch cabinet according to the geometric dimension parameters; Selecting a triangular mesh for meshing the model network of the geometric model; The grid modeling interface is called collaboratively by MATLAB and COMSOL, and the switch cabinet simulation grid model is constructed based on the grid generation result.

3. A switch cabinet partial discharge simulation method as claimed in claim 2, characterized in that: Selecting a triangular mesh for meshing the model network of the geometric model includes: Use triangular mesh for initial segmentation; Setting key boundaries and key areas, wherein the key boundaries include heat dissipation boundaries and insulation boundaries, and the key areas include switch cabinet component structural positions; The key boundaries and key areas are refined and subdivided.

4. A switch cabinet partial discharge simulation method according to claim 1, characterized in that: Fitting a curve of material parameters changing with temperature according to the switch cabinet material data includes: Obtain the relative dielectric constant and conductivity values ​​of the internal conductors and insulating partitions of the switch cabinet at different temperatures; The nonlinear functional relationship between the relative dielectric constant and the conductivity value and the temperature is fitted by the least square method to obtain the curve of the material parameter changing with temperature.

5. A switch cabinet partial discharge simulation method according to claim 1, characterized in that: The electromagnetic simulation of the switch cabinet is performed to calculate the heat source of the switch cabinet and obtain the temperature field and flow field distribution inside the switch cabinet, including: A loss separation model is used to solve the switch cabinet loss, wherein the switch cabinet loss includes: the loss of each current-carrying conductor and the loss of the switch cabinet magnetic material at the fundamental frequency; Utilize the correction method of the influence of high-order harmonics on losses to calculate the magnetic material losses under non-sinusoidal currents; The temperature field and flow field simulation is performed based on the loss to determine the electromagnetic heat generated by the switch cabinet as the heat source of the temperature-flow field coupling, and the temperature field and flow field distribution inside the switch cabinet are obtained.

6. A switch cabinet partial discharge simulation method as claimed in claim 5, characterized in that: The loss separation model is used to solve the switch cabinet loss, including: Through the current-carrying conductor loss formula: P = K h f α B β +K e (fB) 2 , calculate the loss of each current-carrying conductor, where B is a function of the magnetic flux density and the coefficient K is h , K e , a and b are obtained by fitting the loss curve data, K e (fB) 2 is the eddy current loss, K h f α B β It is the sum of hysteresis loss and abnormal loss; When high-order harmonics are present, eddy current losses under distorted magnetic flux Among them, σ is the conductivity of the current-carrying conductor, NH is the highest harmonic order, B h is the amplitude of the hth harmonic; The loss of the switchgear magnetic material at the fundamental frequency is calculated by using the hysteresis loss formula and eddy current loss formula of the magnetic material. The hysteresis loss formula of the magnetic material is: The formula for eddy current loss is: Among them, k h =I h / I l , is the ratio of the hth harmonic current to the effective value of the fundamental current, P WR is the hysteresis loss of the magnetic material under fundamental wave conditions, P WEI is the eddy current loss of the magnetic material at the fundamental frequency, h = f h / f l It is the ratio of the hth harmonic current frequency to the fundamental current frequency.

7. A switch cabinet partial discharge simulation method as claimed in claim 5, characterized in that: The temperature field and flow field simulation comprises: The electromagnetic heat generated by the switch cabinet is used as the heat source of the temperature-flow field. The heat dissipation inside the switch cabinet is achieved through air convection. The entire heat dissipation process satisfies the conservation of mass, momentum and energy. The temperature-flow field coupling simulation is performed based on the conservation equation, where the conservation equation is: in, is the temperature, λ and S are the diffusion coefficient term and the generalized source term respectively, ρ is the air density, and v and u are the velocity vectors in the x and y directions respectively.

8. A switch cabinet partial discharge simulation method according to claim 1, characterized in that: The material parameter versus temperature curve, the temperature field inside the switch cabinet, and the flow field distribution are grid-mapped, including: The material parameter variation curve with temperature, the temperature field and flow field distribution inside the switch cabinet are transferred to the electric field simulation calculation grid through the interpolation method.

9. A switch cabinet partial discharge simulation system, characterized in that: Steps for implementing a switch cabinet partial discharge simulation method as described in any one of claims 1 to 8, wherein the switch cabinet partial discharge simulation system comprises: A parameter acquisition module, which is used to acquire geometric size parameters of the switch cabinet and construct a switch cabinet simulation grid model; A data acquisition module, wherein the data acquisition module is used to acquire switch cabinet material data, wherein the switch cabinet material data is experimental data of relevant materials on the switch cabinet at different temperatures, and a material parameter variation curve with temperature is fitted according to the switch cabinet material data; An electromagnetic simulation module, which is used to perform electromagnetic simulation on the switch cabinet, calculate the heat source of the switch cabinet, and obtain the temperature field and flow field distribution inside the switch cabinet; A data coupling module is used to map the material parameter temperature variation curve, the temperature field and flow field distribution inside the switch cabinet to grid data, and couple them to the switch cabinet simulation grid model.

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