Transformer simulation method and system based on multi-physics field coupling

Abstract

The invention provides a transformer simulation method and system based on multi-physics field coupling, and the method comprises the steps: building a transformer simulation grid model according to the geometric dimension parameters of a transformer; fitting to obtain a nonlinear change curve of the material parameters along with the temperature based on the change rule of the related parameters of the transformer related material along with the temperature at different temperatures; transformer electromagnetic simulation is carried out, a transformer heat source is calculated, iron core loss and winding loss of silicon steel laminations are solved, loss generated by a transformer iron core and a winding is used as a heat source of temperature-flow field coupling, and distribution of a temperature field and a flow field in the transformer is determined; and mapping the distribution of the temperature field and the flow field in the transformer and the nonlinear change curve of the transformer material into the constructed transformer simulation grid model to realize deep coupling. The practical operation condition of the transformer can be effectively simulated, guidance is provided for safe and stable operation of the transformer, and safe and stable operation of the transformer is guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of high voltage and insulation, and particularly relates to a transformer simulation method and system based on multi-physical field coupling. Background Art

[0002] The statements in this part only provide background technical information related to the present invention, and do not necessarily constitute prior art.

[0003] With the continuous expansion of the power grid scale and the continuous improvement of the transformer voltage level, as an important device in the power system, the operating conditions of the transformer are very complex. Using the simulation method to conduct comprehensive research on the transformer can effectively provide guidance for ensuring its safe and stable operation. However, the operating environment of the transformer is complex, the properties of the insulation system materials are greatly affected by temperature, with obvious non-linearity, and are subject to the multiple coupling effects of multiple physical fields such as temperature field, flow field and electromagnetic field. The coupling relationship is complex and the influence is significant, and the insulation system of the transformer may undergo irreversible deterioration.

[0004] In the prior art, the temperature field and the electric field are not coupled, and only rely on the variation law of material parameters with temperature to simulate the electric field distribution at a certain temperature; at the same time, the non-linear relationship between material parameters such as conductivity and relative permittivity and the electric field is not considered, and the electro-thermal mapping coupling relationship is severed, resulting in inaccurate coupling results. Summary of the Invention

[0005] In order to solve the above problems, the present invention proposes a transformer simulation method and system based on multi-physical field coupling. The present invention can effectively simulate the operation of an actual transformer, provide guidance for the safe and stable operation of the transformer, and ensure its safe and stable operation.

[0006] According to some embodiments, the present invention adopts the following technical solutions:

[0007] A transformer simulation method based on multi-physical field coupling includes the following steps:

[0008] Construct a transformer simulation grid model according to the geometric dimension parameters of the transformer;

[0009] Based on the variation law of relevant parameters of transformer-related materials at different temperatures with temperature, fit a non-linear variation curve of material parameters with temperature;

[0010] Conduct electromagnetic simulation of the transformer, calculate the heat source of the transformer, solve the core loss and winding loss of the silicon steel laminations, and use the losses generated by the transformer core and windings as the heat source for temperature-flow field coupling to determine the internal temperature field and flow field distribution of the transformer;

[0011] Map the internal temperature field and flow field distribution of the transformer and the nonlinear change curve of the transformer material into the constructed transformer simulation grid model to achieve deep coupling.

[0012] As an alternative implementation, the specific process of constructing the transformer simulation grid model includes constructing a transformer geometric model according to the geometric dimension parameters of the transformer, performing an initial triangular network meshing on the constructed transformer geometric model, and performing multiple refined meshings on key boundaries and regions to obtain the transformer simulation grid model.

[0013] As an alternative implementation, the material parameters include conductivity and / or relative permittivity.

[0014] As an alternative implementation, the variation law of the relevant parameters of the transformer-related materials with temperature is obtained through experiments, and the values of the relative permittivity and / or conductivity of the transformer insulating oil and insulating cardboard at different temperatures are obtained through experiments.

[0015] As an alternative implementation, the functional relationships of the relative permittivity and conductivity with temperature are obtained by fitting using the least squares method.

[0016] As an alternative implementation, a loss separation model is used to solve the core loss of the silicon steel laminations, and when solving, the core loss of the silicon steel laminations is divided into hysteresis loss, eddy current loss, and abnormal loss.

[0017] As an alternative implementation, the winding loss includes ohmic loss and eddy current loss at the fundamental frequency, as well as the correction of the influence of higher harmonics on the corresponding losses, and the final winding loss is obtained comprehensively.

[0018] As an alternative implementation, the specific process of mapping the internal temperature field and flow field distribution of the transformer and the nonlinear change curve of the transformer material into the constructed transformer simulation grid model includes: taking the core loss and winding loss of the transformer as the heat source of the temperature-flow field, using a power device to make the insulating oil dissipate heat through convection, expressing each conservation equation using equations, and transferring them to the transformer simulation grid model through interpolation;

[0019] Considering the nonlinear change curve of the transformer-related materials, transfer it to the transformer simulation grid model through interpolation to achieve the bidirectional coupling of the temperature-flow field to the electric field.

[0020] A transformer simulation system based on multi-physical field coupling includes:

[0021] An electric field model construction module configured to construct a transformer simulation grid model according to the geometric dimension parameters of the transformer;

[0022] A material influence determination module, configured to fit a non-linear change curve of material parameters with temperature based on the change law of relevant parameters of transformer-related materials with temperature at different temperatures;

[0023] A temperature field-flow field distribution module, configured to perform electromagnetic simulation of a transformer, calculate the heat sources of the transformer, solve the core loss and winding loss of silicon steel laminations, and use the losses generated by the transformer core and windings as the heat sources for temperature-flow field coupling to determine the internal temperature field and flow field distribution of the transformer;

[0024] A deep coupling module, configured to map the internal temperature field and flow field distribution of the transformer and the non-linear change curve of the transformer material into the constructed transformer simulation grid model to achieve deep coupling.

[0025] An electronic device, including a memory, a processor, and computer instructions stored on the memory and running on the processor. When the computer instructions are run by the processor, the steps in the above method are completed.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] When setting material parameters in the simulation of the present invention, the influence of constant material parameters on multi-field coupling is avoided, the non-linear change of the properties of transformer insulation materials with temperature is considered, and the non-linear change curve is fitted, which can more accurately reflect the influence of temperature and is conducive to realizing the deep coupling of the temperature field and the electric field.

[0028] When calculating the heat sources of the transformer in the present invention, the electromagnetic heat generated by the transformer core and windings is used as the simulation heat source for the temperature flow field, and data transfer is realized through the node mapping method and the interpolation method to avoid splitting the electro-thermal coupling.

[0029] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following specific preferred embodiments are given, and in conjunction with the accompanying drawings, the detailed description is as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0031] Figure 1 is a flowchart of a transformer simulation method based on multi-physical field coupling in this embodiment;

[0032] Figure 2 is a temperature field distribution diagram of a transformer based on multi-physical field coupling in this embodiment;

[0033] Figure 3 is a flow field distribution diagram of a transformer based on multi-physical field coupling in this embodiment;

[0034] Figure 4 is the electric field intensity distribution diagram of the transformer based on multi - physical - field coupling in this embodiment. Specific implementation manners

[0035] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0036] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanations of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0037] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0038] Embodiment 1

[0039] Aiming at the problem that the prior art separates the coupling between multiple physical fields, in order to effectively perform transformer modeling and simulation and ensure its safe and stable operation, this embodiment provides a multi - physical - field coupling simulation method for transformers, as Figure 1 shown, including the following steps:

[0040] Step 1: Obtain the geometric dimension parameters of the transformer and construct a transformer simulation grid model.

[0041] According to the geometric dimension parameters of the transformer, first construct the geometric model of the transformer, select a triangular network for the initial meshing of the geometric model, and perform multiple ultra - fine mesh refinements on the key boundaries and regions to complete the overall mesh generation of the transformer model.

[0042] In this embodiment, the grid modeling interface can be jointly called by MATLAB and COMSOL, and the programming language is used to quickly and efficiently establish the transformer model. That is, when performing transformer modeling in COMSOL, the coordinated software interface of COMSOL Multiphysics with MATLAB is combined. The program commands for controlling the MATLAB file are programmed in JAVA language, and through MATLAB, the drawing of the transformer geometric model can be controlled to achieve fast and accurate model establishment.

[0043] In this embodiment, in the COMSOL software, first perform an initial triangular meshing on the geometric model, and then perform a super-fine meshing on key parts such as the static rings and angle rings at the ends of the transformer windings, with the aim of enabling more accurate calculations of the actual working conditions at locations with complex structures and multi-physical field distributions.

[0044] In some embodiments, a distributed meshing can also be set for the transformer model. First, use triangular mesh meshing as the initial meshing, then perform a secondary meshing on the ends of the transformer windings, and perform a super-fine tertiary meshing for structures such as static rings and angle rings to achieve the overall mesh meshing of the transformer.

[0045] The boundary refers to the boundary set in the COMSOL software, including heat dissipation boundaries in the temperature field - flow field, insulation and other boundary conditions in the electric field, including the first type of boundary condition and the second type of boundary condition. The key area refers to the key meshing positions at the ends of the transformer windings, such as structures like static rings and angle rings.

[0046] Step 2: Obtain the experimental data of the transformer-related materials at different temperatures, such as the variation laws of conductivity, relative permittivity, etc. with temperature, and fit the non-linear variation curve of the material parameters with temperature by the least squares method.

[0047] In this embodiment, fitting the non-linear curve of the material parameters with temperature includes: obtaining the values of the relative permittivity and conductivity of the transformer insulating oil and insulating cardboard at different temperatures, and fitting the functional relationships of the relative permittivity and conductivity with temperature by the least squares method, as shown in Table 1:

[0048] Table 1 Functional relationships of relative permittivity and conductivity with temperature

[0049]

[0050] Step 3: Conduct electromagnetic simulation of the transformer, calculate the heat sources of the transformer, and determine the internal temperature field and flow field distributions of the transformer.

[0051] The specific process includes: The electromagnetic simulation module in COMSOL can be called to solve the core loss of the silicon steel laminations using the loss separation model. At the same time, solve the ohmic loss and eddy current loss of the windings at the fundamental frequency respectively, and then add the correction for the influence of higher harmonics on the loss to calculate the winding loss under non-sinusoidal current conditions. Finally, take the electromagnetic heat generated by the transformer core and windings as the heat source for the temperature - flow field coupling to obtain the internal temperature field and flow field distributions of the transformer, realizing the unidirectional coupling of the electric field to the temperature - flow field.

[0052] The solution of the core loss by the loss separation model in this embodiment includes: dividing the core loss of the silicon steel laminations into hysteresis loss, eddy current loss, and abnormal loss.

[0053] The expression of core loss is shown in Equation (1):

[0054] P = K h f α B β + K e (sfB) 2 (1)

[0055] Among them, the first term on the right side of the equation is the sum of hysteresis loss and abnormal loss, and the second term is eddy current loss. In the formula, B is a function of magnetic flux density, and s is the thickness ratio of silicon steel laminations. Coefficients K h , K e , a and b are obtained by fitting the input loss curve data.

[0056] When high-order harmonics are present, through derivation, the eddy current loss under distorted magnetic flux is as shown in Equation (2):

[0057]

[0058] Among them, σ is the conductivity of the silicon steel sheet, d is the thickness of a single silicon steel sheet, NH is the highest order of the harmonics, and B h is the amplitude of the h-th harmonic.

[0059] Furthermore, the solving of winding loss includes: when solving the transformer winding loss, the ohmic loss and eddy current loss of the winding are solved separately. The calculation formula of the ohmic loss generated in the winding under harmonic conditions is as shown in Equation (3).

[0060]

[0061] Among them, k h = I h / I l , which is the ratio of the effective value of the h-th harmonic current to the fundamental current, and P WR is the ohmic loss of the winding under fundamental conditions.

[0062] The calculation formula of the eddy current loss in the winding under harmonic conditions is as shown in Equation (4).

[0063]

[0064] Among them, P WEI is the eddy current loss of the winding at the fundamental frequency, and h = f h / f l is the ratio of the frequency of the h-th harmonic current to the fundamental current frequency.

[0065] Step 4: Map the grid data of the temperature field-flow field simulation results.

[0066] In this embodiment, data transmission is achieved through the node mapping method. The simulation results of the temperature field - flow field and the nonlinear relationship curve of the transformer material properties are transmitted to the grid of the transformer simulation grid model through the interpolation method to achieve deep electro-thermal coupling.

[0067] In this embodiment, when setting each material parameter in the COMSOL software, the nonlinear relationship expression of the material is input into the software, and the COMSOL software will perform iterative calculations by itself, thereby obtaining the temperature field - flow field distribution considering material nonlinearity. 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 can be set in the COMSOL software. By setting according to the above process in the COMSOL software, the result transmission can be achieved, realizing deep coupling.

[0068] The temperature - flow field coupling simulation includes: regarding the core loss and winding loss of the transformer as the heat sources of the temperature - flow field, and power devices such as oil pumps enable the insulating oil to dissipate heat through convection. The entire heat dissipation process satisfies the conservation of mass, momentum, and energy, and the corresponding conservation equations are represented by the general equation (5):

[0069]

[0070] Among them, represents a certain variable, which is the temperature here; λ and S are the diffusion coefficient term and the generalized source term respectively; ρ is the density of the insulating oil; v and u are the velocity vectors in the x and y directions respectively.

[0071] The existence of the internal temperature gradient of the transformer will inevitably lead to the nonlinear change of the material properties of the insulating oil and insulating paper. Therefore, considering the fitting curve of the relevant material parameters varying with temperature in step two, data is transmitted through the interpolation method to achieve the bidirectional coupling of the temperature - flow field to the electric field.

[0072] Figures 2 - 4 They are the distribution diagrams of the coupled temperature field, flow field, and electric field respectively. By comparing the simulation results with the actual experimental results, the coupled results (such as temperature, flow velocity, field strength, etc.) can be more in line with the experimental results of the actual working conditions.

[0073] Embodiment Two

[0074] A transformer simulation system based on multi-physical field coupling includes:

[0075] An electric field model construction module, configured to construct a transformer simulation grid model according to the geometric dimension parameters of the transformer;

[0076] A material influence determination module, configured to fit the nonlinear change curve of the material parameters with temperature based on the variation law of the relevant parameters of the transformer-related materials at different temperatures;

[0077] A temperature field - flow field distribution module, which is configured to perform electromagnetic simulation of a transformer, calculate heat sources of the transformer, solve core losses and winding losses of silicon steel laminations, and use the losses generated by the transformer core and windings as heat sources for temperature - flow field coupling to determine the internal temperature field and flow field distribution of the transformer;

[0078] A deep coupling module, which is configured to map the internal temperature field and flow field distribution of the transformer and the non - linear change curve of transformer materials into the constructed transformer simulation grid model to achieve deep coupling.

[0079] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer - usable storage media (including but not limited to disk storage, CD - ROM, optical storage, etc.) containing computer - usable program code.

[0080] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general - purpose computer, a special - purpose computer, an embedded processor, or other programmable data - processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data - processing devices generate means for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0081] These computer program instructions can also be stored in a computer - readable memory that can direct a computer or other programmable data - processing device to work in a specific manner, so that the instructions stored in the computer - readable memory generate a manufactured article including instruction means, and the instruction means implement the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0082] These computer program instructions can also be loaded onto a computer or other programmable data - processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer - implemented process, and thus the instructions executed on the computer or other programmable device provide means for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1Steps of functions specified in one or more boxes.

[0083] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made by those skilled in the art without creative efforts within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A transformer simulation method based on multi-physical field coupling, characterized in that Including the following steps: Construct a transformer simulation grid model according to the geometric dimension parameters of the transformer; Based on the variation law of the relevant parameters of the transformer-related materials with temperature at different temperatures, fit to obtain the non-linear variation curve of the material parameters with temperature; Conduct electromagnetic simulation of the transformer, calculate the heat source of the transformer, solve the core loss and winding loss of the silicon steel laminations, take the losses generated by the transformer core and winding as the heat source for temperature-flow field coupling, and determine the internal temperature field and flow field distribution of the transformer; Map the internal temperature field and flow field distribution of the transformer and the non-linear variation curve of the transformer material to the constructed transformer simulation grid model to achieve deep coupling.

2. The simulation method of a transformer based on multi-physical field coupling according to claim 1, characterized in that, The specific process of constructing the transformer simulation grid model includes constructing a transformer geometric model according to the geometric dimension parameters of the transformer, performing an initial triangular network meshing on the constructed transformer geometric model, and performing multiple refined meshing on the key boundaries and regions to obtain the transformer simulation grid model.

3. A simulation method of a transformer based on multi-physical field coupling according to claim 1, characterized in that, The material parameters include conductivity and / or relative permittivity.

4. A transformer simulation method based on multi-physical field coupling as described in claim 1, characterized in that the transformer The variation law of the relevant parameters of the relevant materials with temperature at different temperatures is obtained through experiments, and the values of the relative permittivity and / or conductivity of the transformer insulating oil and insulating paperboard at different temperatures are obtained through experiments.

5. The simulation method of a transformer based on multi-physical field coupling according to claim 1, characterized in that, Use the least squares method to fit the functional relationship between the relative permittivity and conductivity and temperature.

6. The simulation method of a transformer based on multi-physical field coupling according to claim 1, characterized in that Adopt a loss separation model to solve the core loss of the silicon steel laminations, and when solving, divide the core loss of the silicon steel laminations into hysteresis loss, eddy current loss and abnormal loss.

7. A transformer simulation method based on multi-physical field coupling according to claim 1, characterized in that, The winding loss includes ohmic loss and eddy current loss at the fundamental frequency, as well as the correction of the influence of higher harmonics on the corresponding losses, and finally the winding loss is obtained comprehensively.

8. The simulation method of a transformer based on multi-physical field coupling according to claim 1, characterized in that, The specific process of mapping the internal temperature field and flow field distribution of the transformer and the non-linear variation curve of the transformer material to the constructed transformer simulation grid model includes: taking the transformer core loss and winding loss as the heat source of the temperature-flow field, using a power device to make the insulating oil dissipate heat through convection, expressing each conservation equation by an equation, and transferring it to the transformer simulation grid model through interpolation; Considering the non-linear variation curve of the transformer-related materials, transfer it to the transformer simulation grid model through interpolation to achieve bidirectional coupling of the temperature-flow field to the electric field.

9. A transformer simulation system based on multi-physical field coupling, characterized in that, Including: An electric field model construction module configured to construct a transformer simulation grid model according to the geometric dimension parameters of the transformer; A material influence determination module configured to fit to obtain the non-linear variation curve of the material parameters with temperature based on the variation law of the relevant parameters of the transformer-related materials with temperature at different temperatures; A temperature field-flow field distribution module configured to conduct electromagnetic simulation of the transformer, calculate the heat source of the transformer, solve the core loss and winding loss of the silicon steel laminations, take the losses generated by the transformer core and winding as the heat source for temperature-flow field coupling, and determine the internal temperature field and flow field distribution of the transformer; A deep coupling module configured to map the internal temperature field and flow field distribution of the transformer and the non-linear variation curve of the transformer material to the constructed transformer simulation grid model to achieve deep coupling.

10. An electronic device, characterized in that, Comprising a memory and a processor, and computer instructions stored on the memory and running on the processor, when the computer instructions are run by the processor, the steps in the method according to any one of claims 1-8 are completed.

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