A multi-physics coupling modeling method and system for CLCC converter

Abstract

A multi-physical field coupling modeling method and system for a CLCC converter. The method includes: simplifying the initial CLCC converter three-dimensional model and selecting a calculation method for the physical field; setting material parameters, boundary conditions and initial state for the simplified CLCC converter three-dimensional model; performing finite element meshing and refinement on the CLCC converter three-dimensional model to form a finite element three-dimensional model of the CLCC converter; performing electromagnetic coupling simulation on the finite element three-dimensional model of the CLCC converter and calculating the electric displacement vector and magnetic field intensity vector of the CLCC converter; calculating the distribution of the temperature field of the CLCC converter; updating the electrical material parameters of the CLCC converter and performing iterative calculations until the calculation requirements of different calculation methods are met. The present invention provides comprehensive electromagnetic thermal field coupling modeling, which effectively fills the gap in the field of CLCC numerical simulation.

Description

Technical Field

[0001] The present invention belongs to the technical field of high voltage direct current transmission, and more specifically, relates to a multi-physical field coupling modeling method and system for a CLCC converter. Background Art

[0002] In HVDC multi-infeed systems, commutation failure is a challenging problem. To address this problem, the State Grid Intelligent Research Institute applied the innovatively designed new CLCC (Controllable Line-Commutated Converter) for the first time in the Genan DC equipment renovation project, providing a solution with controllable shutdown capability. As a new type of equipment, the application of CLCC converter demonstrates the urgent need for efficient and reliable converters in modern power grid technology.

[0003] Domestic and foreign scholars have conducted relevant research on modeling and solution methods for key power devices in converters, such as thyristors and IGBTs. These research results include the successful establishment and verification of a three-dimensional finite element model of thyristor multi-material layer coupling, which provides an important means for accurately simulating the internal structure and heat transfer characteristics of thyristors. For IGBT power devices in converters, the FS-IGBT physical model has been developed, and the stray parameters of the device have been obtained through impedance measurement methods. This step is of great significance to improving the convergence of the model. In addition, by establishing a finite element thermoelectric coupling model based on the internal structure of IGBT power devices, researchers can analyze the evolution of IGBT failure mechanisms and their critical energy values ​​under different initial temperatures and bus voltage conditions.

[0004] For example, Toshiba has been granted a US patent (US11658653B2) to disclose a simulation method for power semiconductor devices such as IGBT, and ABB has been granted a US patent (US11477213B2) to disclose a converter simulation method for HVDC systems, etc.

[0005] However, the above studies mainly modeled single key components, but lacked numerical simulation and analysis of the CLCC converter as a whole. In particular, considering the heat generation, electrical and magnetic characteristics of the converter in steady and transient states, as well as the multi-physics finite element model that introduces the equivalent circuit parameters of each module inside it, current research has not fully covered these aspects.

[0006] These factors together point out the urgent need for further research and improvement of high-fidelity modeling technology for CLCC converters. Therefore, a multi-physics field coupling modeling method and system for CLCC converters with high convergence is urgently needed. Summary of the invention

[0007] In order to solve the deficiencies in the prior art, the present invention provides a CLCC converter multi-physical field coupling modeling method and system.

[0008] The present invention adopts the following technical solution.

[0009] A first aspect of the present invention provides a CLCC converter multi-physics field coupling modeling method, comprising the following steps:

[0010] Based on the physical fields to be calculated, including electric field, magnetic field and thermal field, the initial CLCC converter 3D model is simplified, and steady-state calculation or transient calculation is selected;

[0011] Set material parameters, boundary conditions and initial state for the simplified CLCC converter 3D model;

[0012] Performing finite element meshing and refinement on the CLCC converter three-dimensional model to form a finite element three-dimensional model of the CLCC converter;

[0013] Performing electromagnetic coupling simulation on the finite element three-dimensional model of the CLCC converter, measuring the voltage or current of each distribution point in the calculation domain of the finite element three-dimensional model of the CLCC converter; and calculating the electric displacement vector and magnetic field intensity vector of the CLCC converter;

[0014] According to the obtained electric field and magnetic field distribution of the CLCC converter, the distribution of the temperature field of the CLCC converter is calculated;

[0015] According to the obtained temperature field distribution, the electrical material parameters of the CLCC converter are updated, and the electromagnetic coupling simulation step is returned to perform iterative calculations until the calculation requirements of different calculation methods are met.

[0016] Preferably, the simplified CLCC converter three-dimensional model includes:

[0017] (1) Simplify the bolts, threads and various material joints in the 3D model of the CLCC converter;

[0018] (2) The completely shielded interior of the conductor, indicator lights, and color and texture information in the 3D model of the CLCC converter are omitted from the model;

[0019] (3) Simplify the chamfers and slopes in the 3D model of the CLCC converter.

[0020] Preferably, in the calculation process of different physical fields, the principle of minimum simplification is followed, and any element that cannot be simplified in any physical field must be retained. For all physical fields, the simplified CLCC converter three-dimensional model is the same.

[0021] Preferably, when the DC side physical field is calculated first, steady-state calculation is adopted, and when the AC side physical field is calculated first, transient calculation is adopted.

[0022] Preferably, setting material parameters for the simplified CLCC converter three-dimensional model includes: setting corresponding initial conductivity, magnetic permeability and heat transfer coefficient according to material information used by the CLCC converter;

[0023] The boundary conditions for the simplified CLCC converter three-dimensional model are as follows: for electrostatic field simulation, the voltage boundary conditions and open boundary conditions need to be set according to the actual working conditions of the CLCC converter; in magnetic field simulation, the current boundary conditions and open boundary conditions are set according to the actual working conditions of the CLCC converter and the ports with actual known current input values; for thermal field simulation, the temperature conduction boundary conditions are set according to the operating environment of the CLCC converter; the actual working conditions of the CLCC converter refer to the normal, faulty, DC and AC working conditions of the CLCC; the actual operating environment of the CLCC converter refers to the temperature and humidity of the gate chamber when the CLCC equipment is running;

[0024] Setting the initial state of the simplified CLCC converter three-dimensional model includes: setting the actual ambient temperature, initial electric field and initial magnetic field of the CLCC converter.

[0025] Preferably, performing finite element meshing and refinement on the CLCC converter three-dimensional model includes:

[0026] When the side length or curvature radius of the CLCC component r<10cm, the mesh is refined in the area L<2r, and the mesh refinement value is the maximum length of each mesh <0.2*r, where L represents the distance between each grid point and the midpoint of the straight edge of the component or the vertex of the curve.

[0027] Preferably, an electromagnetic coupling simulation is performed on the finite element three-dimensional model of the CLCC converter, and the voltage or current of each distribution point in the calculation domain of the finite element three-dimensional model of the CLCC converter is measured; and the electric displacement vector of the CLCC converter is calculated. and the magnetic field strength vector include:

[0028] Set the voltage according to the rated voltage value of CLCC in different working states and open the corresponding boundary conditions;

[0029] Set the preset total simulation time T, number of time steps N, and time step size for electromagnetic coupling simulation as required and relative tolerance ,in ; Set the solution order to electromagnetic-heat transfer:

[0030] Calculate the electric field strength vector and the magnetic flux density vector ;

[0031] Based on the electric field strength vector and the magnetic flux density vector , the electric displacement vector is obtained by using the constitutive relationship and the magnetic field strength vector .

[0032] Preferably, the relative tolerance The value is .

[0033] Preferably, a stiffness matrix is ​​formed based on the material parameters and grid distribution of the material in the calculation area. ; According to the boundary conditions and the voltage and current parameters of the CLCC converter under different working conditions, a source vector matrix is ​​formed , solve the following matrix equation:

[0034] (1)

[0035] Get the electromotive force distribution matrix , and according to the following equation:

[0036] (2)

[0037] Solving for the electric field strength vector ; Use the same solution method to obtain the magnetic vector potential ; and according to Get the magnetic flux density vector .

[0038] Preferably, the electric displacement vector and the magnetic field strength vector The solution is shown in the following formula:

[0039] (3)

[0040] (4)

[0041] Where:

[0042] and are the dielectric constant and magnetic permeability in vacuum respectively;

[0043] and are the relative dielectric constant and relative magnetic permeability of the CLCC converter material respectively.

[0044] Preferably, calculating the distribution of the temperature field includes:

[0045] Calculate the generated heat Q, expressed as follows:

[0046] (5)

[0047] Where:

[0048] , , They are magnetic flux density vector, electric field intensity vector and magnetic field intensity vector respectively;

[0049] is the total current density vector;

[0050] They are the total heat, joule heat, and induced heat generated by CLCC;

[0051] Re represents the real part of a complex number;

[0052] Set Q as the heat source, calculate its temperature rise and heat transfer, and solve for the temperature distribution of each point in the device ; Wherein, x, y, z are the x-coordinate, y-coordinate and z-coordinate of the temperature field of the CLCC converter.

[0053] Preferably, updating the electrical material parameters of the CLCC converter includes: updating the relative dielectric constant, electrical conductivity and magnetic permeability of the electrical material according to the relationship between the preset initial dielectric constant, electrical conductivity, magnetic permeability and temperature.

[0054] Preferably, when the calculation method for the physical field is steady-state calculation, the time step number N is not considered, and the iterative process for the model voltage or current is:

[0055] When all distribution points in the calculation domain of the finite element three-dimensional model of the CLCC converter meet , the iterative calculation is finished, and the electric field distribution, magnetic field distribution and temperature field distribution of the i-th time are output as the final model;

[0056] When a certain distribution point in the calculation domain of the finite element three-dimensional model of the CLCC converter satisfies , repeat the iterative steps;

[0057] Wherein, M is the voltage or current measured at each distribution point in the calculation domain of the finite element three-dimensional model of the CLCC converter; i is the number of calculations, i=2, 3…; is the relative tolerance.

[0058] Preferably, when the calculation method for the physical field is transient calculation, the number of time steps N is considered, and the iterative process is:

[0059] A certain distribution point in the calculation domain of the finite element three-dimensional model of the CLCC converter satisfies , repeat the iterative steps;

[0060] When all distribution points in the calculation domain of the finite element three-dimensional model of the CLCC converter meet , but all time steps have not been solved, then enter the next time step and repeat the iteration steps; when all distribution points in the calculation domain of the finite element three-dimensional model of the CLCC converter meet After solving the total number of time steps N, the iterative calculation ends, and the electric field distribution, magnetic field distribution and temperature field distribution of the ith time are output as the final model;

[0061] Wherein, M is the voltage or current measured at each distribution point in the calculation domain of the finite element three-dimensional model of the CLCC converter; i is the number of calculations, i=2, 3…; is the relative tolerance.

[0062] A second aspect of the present invention provides a CLCC converter multi-physics field coupling modeling system, including a three-dimensional model simplification module, a parameter condition setting module, a finite element segmentation module, an electromagnetic coupling simulation module, a temperature field distribution calculation module and an iterative calculation module;

[0063] The 3D model simplification module simplifies the initial CLCC converter 3D model based on the physical field to be calculated and selects the calculation method of the physical field;

[0064] The parameter condition setting module sets material parameters, boundary conditions and initial state for the simplified CLCC converter three-dimensional model;

[0065] The finite element meshing module is used to perform finite element meshing and refinement on the CLCC converter three-dimensional model to form a finite element three-dimensional model of the CLCC converter;

[0066] The electromagnetic coupling simulation module performs electromagnetic coupling simulation on the finite element three-dimensional model of the CLCC converter, measures the voltage or current of each distribution point in the calculation domain of the finite element three-dimensional model of the CLCC converter; and calculates the electric displacement vector and magnetic field intensity vector of the CLCC converter;

[0067] The temperature field distribution calculation module calculates the distribution of the temperature field of the CLCC converter according to the obtained electric field and magnetic field distribution of the CLCC converter;

[0068] The iterative calculation module is used to update the electrical material parameters of the CLCC converter and perform iterative calculations until the calculation requirements of different calculation methods are met.

[0069] The third aspect of the present invention provides a terminal, including a processor and a storage medium; the storage medium is used to store instructions; the processor is used to operate according to the instructions to execute the steps of the CLCC converter multi-physics coupling modeling method.

[0070] A fourth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the multi-physics coupling modeling method for a CLCC converter.

[0071] Compared with the prior art, the beneficial effects of the present invention include at least:

[0072] (1) Comprehensive electromagnetic thermal field coupling modeling: This paper conducts comprehensive electromagnetic thermal field coupling modeling of CLCC converter valves for the first time, effectively filling the gap in the field of CLCC numerical simulation. This comprehensive modeling method can accurately calculate and reflect the distribution of various physical quantities inside the CLCC converter valve, thus providing an important scientific basis for the design, operation and maintenance of the CLCC converter valve.

[0073] (2) Comprehensive coupling of electromagnetic and thermal fields: This invention is the first to comprehensively couple the electric field, magnetic field and thermal field in the calculation and analysis of CLCC. Compared with the previous single-field simulation, this method more comprehensively reflects the actual operating status of CLCC. It solves the problem of multi-field coupling analysis, thereby providing more accurate technical support for the safe operation of the controllable commutation converter CLCC.

[0074] In summary, the present invention provides a more comprehensive and accurate solution in the modeling and simulation of CLCC converters, which not only improves the scientificity and reliability of converter design, but also provides strong technical support for its safe and efficient operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0076] Figure 1 This is a flow chart of a multi-physics coupling modeling method for a CLCC converter in the present application;

[0077] Figure 2 It is a schematic diagram of a three-dimensional coordinate system of the present application;

[0078] Figure 3 It is a simplified single valve layer model of an embodiment of the present application;

[0079] Figure 4 This is a topological structure diagram of a controllable commutation converter according to an embodiment of the present application;

[0080] Figure 5 This is a structural block diagram of a multi-physics field coupling modeling system for a CLCC converter in the present application. DETAILED DESCRIPTION

[0081] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The described embodiments are only embodiments of a part of the present invention, not all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0082] like Figure 1 As shown, embodiment 1 of the present invention provides a CLCC converter multi-physics field coupling modeling method, comprising the following steps:

[0083] Step 1: Based on the physical field to be calculated, simplify the initial CLCC converter three-dimensional model and select the calculation method of the physical field.

[0084] The simplification of the initial CLCC converter 3D model specifically includes:

[0085] (1) Simplify the bolts, threads and various material joints in the initial CLCC converter 3D model, including: removing the bolts and their interfaces in the model, and simplifying multiple connected metal surfaces into one metal surface;

[0086] (2) Simplify the completely shielded interior of the conductor, indicator lights, and color and texture information in the initial CLCC converter 3D model and remove them from the model;

[0087] (3) Simplify the chamfers and slopes in the initial CLCC converter 3D model to reduce unnecessary computational complexity.

[0088] Further preferably, in the calculation process of different physical fields, the principle of minimum simplification is followed, and any element that cannot be simplified in any physical field must be retained. For example, but not limited to, if element A needs to be ignored in the electric field calculation, but needs to be retained in the thermal field calculation, then element A is retained in the CLCC inverter three-dimensional model; so the simplified model is the same for all physical fields.

[0089] Further preferably, the calculation method of the physical field is divided into steady-state calculation and transient calculation; steady-state calculation is used when focusing on the physical field on the DC side, and transient calculation is used when focusing on the physical field on the AC side.

[0090] Step 2: Set material parameters, boundary conditions and initial states for the simplified CLCC converter 3D model.

[0091] The material parameters for the simplified CLCC converter 3D model are as follows:

[0092] According to the material information used by the CLCC converter, the corresponding initial conductivity, magnetic permeability and heat transfer coefficient are set. Preferably, but not limited to, according to the CLCC converter topology diagram and the actual CLCC converter, the metal components inside the CLCC converter are approximately regarded as ideal conductors, that is, the resistivity is set to 0; according to the material list of each position provided by the CLCC converter manufacturer, the conductivity, relative dielectric constant and magnetic permeability of each material are set, and when setting, each parameter is set to a constant of temperature.

[0093] The boundary conditions for the simplified CLCC converter 3D model include:

[0094] For electrostatic field simulation, it is necessary to set voltage boundary conditions and open boundary conditions according to the actual working conditions of the CLCC converter; in magnetic field simulation, current boundary conditions and open boundary conditions are set according to the actual working conditions of the CLCC converter and the ports with actual known current input values; for thermal field simulation, temperature conduction boundary conditions are set according to the operating environment of the CLCC converter. For example, but not limited to, use "metal contact" to set the input voltage at the input position of the single valve layer model; set the "tangential electric field" boundary condition at the closed metal shell position.

[0095] Further preferably, the actual operating condition of the CLCC converter refers to the CLCC normal, faulty, DC, AC and other operating conditions; and the actual operating environment of the CLCC converter refers to the external conditions such as temperature and humidity of the lock chamber when the CLCC equipment is running.

[0096] Setting the initial state of the simplified CLCC converter three-dimensional model includes:

[0097] Set the actual ambient temperature, initial electric field, and initial magnetic field of the CLCC converter.

[0098] Step 3: According to the requirement of calculation accuracy, the CLCC converter three-dimensional model is meshed and refined by finite element to form a finite element three-dimensional model of the CLCC converter.

[0099] Finite element mesh generation and refinement of the CLCC converter three-dimensional model includes:

[0100] According to the requirements of calculation accuracy, finite element meshing is performed. It mainly includes assigning material parameters to each geometric component and forming a free hexahedral mesh by mapping. In particular, in the process of inverter modeling, multiple mesh refinement operations are performed for important or small parts, such as corners and sharp points of conductors. The basic principles of meshing are as follows:

[0101] Consider the number of grids:

[0102] The number of grids directly affects the calculation accuracy and calculation time. Increasing the number of grids will improve the calculation accuracy, but at the same time the calculation time will also increase. When the number of grids is small, increasing the number of grids can significantly improve the calculation accuracy, but the calculation time will not increase significantly; when the number of grids increases to a certain extent, the accuracy will be improved very little when the number of grids is further increased, but the calculation time will increase significantly. Therefore, these two factors should be weighed and considered comprehensively when determining the number of grids.

[0103] Consider the mesh density:

[0104] In order to adapt to the distribution characteristics of calculation data such as stress, different sizes of grids need to be used in different parts of the structure. There is concentrated stress near the hole, so the grid needs to be denser; the stress gradient in the surrounding area is relatively small, and the grid division is sparse. This reflects the principle of grid division with different densities: in the parts where the calculation data change gradient is large, in order to better reflect the law of data change, a relatively dense grid needs to be used; in the parts where the calculation data change gradient is small, in order to reduce the model scale, the grid should be relatively sparse.

[0105] Consider the unit order:

[0106] The unit order is closely related to the calculation accuracy of the finite element. The units generally have linear, quadratic and cubic forms, among which the units in the quadratic and cubic forms are called high-order units. The curve or surface boundary of the high-order unit can better approximate the curve and surface boundary of the structure, and the high-order interpolation function can approximate the complex field function with higher accuracy, so increasing the unit order can improve the calculation accuracy. However, when the unit order is increased, the number of nodes in the grid will also increase. When the number of grids is the same, the model composed of high-order units is relatively large, so the calculation accuracy and time consumption should be weighed when using it.

[0107] Consider the cell shape:

[0108] The quality of the mesh unit shape has a great impact on the calculation accuracy. A mesh with a bad unit shape may even terminate the calculation. The unit shape evaluation generally has the following indicators: the unit side length ratio, area ratio or volume ratio, with regular triangles, regular tetrahedrons and regular hexahedrons as reference standards; distortion, the degree of torsion within the unit surface and the degree of warping outside the surface; node numbering. The node numbering has a great impact on the bandwidth and wavefront factor of the total rigid matrix during the solution process, thereby affecting the calculation time and storage capacity.

[0109] Consider unit coordination:

[0110] Unit coordination means that the forces and moments on the unit can be transmitted to the adjacent units through the nodes. To ensure unit coordination, the following conditions must be met:

[0111] The nodes of a cell must also be adjacent points, and should not be interior or boundary points.

[0112] The common nodes of adjacent cells have the same degree of freedom properties. In addition, the unit meshes with the same degree of freedom are not necessarily coordinated.

[0113] The basic idea of ​​the mapping method is the bidirectional mapping between the actual graphics and the standard graphics, which consists of three steps:

[0114] According to the parameter equation of the body boundary, the physical domain to be divided is mapped to the parameter space using an appropriate mapping function to form a regular parameter domain;

[0115] Meshing the parameter domain;

[0116] The actual mesh is generated by back-mapping the grid of cells in parameter space into Euclidean space.

[0117] Further preferably, when the side length or curvature radius r of the CLCC component is less than 10 cm, the mesh is refined in the area L<2r, and the mesh refinement value is the maximum length of each mesh <0.2*r, where L represents the distance between each grid point and the midpoint of the straight edge of the component or the vertex of the curve.

[0118] Step 4: Perform electromagnetic coupling simulation on the finite element three-dimensional model of the CLCC converter, measure the voltage or current of each distribution point in the calculation domain of the finite element three-dimensional model of the CLCC converter; and calculate the electric displacement vector of the CLCC converter and the magnetic field strength vector .

[0119] Step 4 specifically includes:

[0120] Step 4.1: Set the voltage according to the rated voltage value of CLCC in different working states, and open the corresponding boundary conditions according to step 2.

[0121] Step 4.2: Set the preset total simulation time T, number of time steps N, and time step size of the electromagnetic coupling simulation as required and relative tolerance ,in ; Set the solution order to electromagnetic-heat transfer.

[0122] Further preferably, the relative tolerance for .

[0123] Step 4.3: Calculate the electric field strength vector and the magnetic flux density vector ;

[0124] According to the material parameters and grid distribution of the materials in the calculation area, a stiffness matrix is ​​formed ; According to the boundary conditions and the voltage and current parameters of the CLCC converter under different working conditions, a source vector matrix is ​​formed , solve the following matrix equation:

[0125] (1)

[0126] Get the electromotive force distribution matrix , and according to the following equation:

[0127] (2)

[0128] Solving for the electric field strength vector ; Use the same solution method to obtain the magnetic vector potential ; and according to Get the magnetic flux density vector .

[0129] Step 4.4: Based on the electric field strength vector and the magnetic flux density vector , the electric displacement vector is obtained by using the constitutive relationship and the magnetic field strength vector ;

[0130] Electric displacement vector and the magnetic field strength vector The solution is shown in the following formula:

[0131] (3)

[0132] (4)

[0133] Where:

[0134] and are the dielectric constant and magnetic permeability in vacuum respectively;

[0135] and are the relative dielectric constant and relative magnetic permeability of the CLCC converter material respectively.

[0136] Step 5: Based on the electric field and magnetic field distribution of the CLCC converter obtained in step 4, calculate the distribution of the temperature field of the CLCC converter.

[0137] According to the electric field and magnetic field distribution of the CLCC converter obtained in step 4, the distribution of the temperature field is calculated including:

[0138] Step 5.1: Calculate the generated heat Q, expressed as follows:

[0139] (5)

[0140] Where:

[0141] , , They are magnetic flux density vector, electric field intensity vector and magnetic field intensity vector respectively;

[0142] is the total current density vector;

[0143] They are the total heat, joule heat, and induced heat generated by CLCC;

[0144] Re represents the real part of a complex number.

[0145] Step 5.2: Set Q as the heat source, calculate its temperature rise and heat transfer, and solve for the temperature distribution of each point in the device. ; Wherein, x, y, z are the x-coordinate, y-coordinate and z-coordinate of the temperature field of the CLCC converter.

[0146] Step 6: According to the temperature field distribution obtained in step 5, update the electrical material parameters of the CLCC converter, and return to step 4 for iterative calculation until the calculation requirements of different calculation methods are met.

[0147] The relative dielectric constant, conductivity and permeability of the electrical material are updated based on the relationship between the preset initial dielectric constant, conductivity, permeability and temperature.

[0148] Further preferably, when the material used is aluminum alloy 6063, the relationship between conductivity and temperature is expressed by the following formula:

[0149] (6)

[0150] Where:

[0151] is the conductivity,

[0152] For temperature.

[0153] As the conductivity of other materials does not change significantly, a constant conductivity of 20 degrees is used.

[0154] Further preferably, when the calculation method of the physical field is steady-state calculation, the number of time steps N is not considered, and the iterative process of the model voltage or current is:

[0155] When all distribution points in the calculation domain of the finite element three-dimensional model of the CLCC converter meet , the iterative calculation is finished, and the electric field distribution, magnetic field distribution and temperature field distribution of the i-th time are output as the final model;

[0156] When a certain distribution point in the calculation domain of the finite element three-dimensional model of the CLCC converter satisfies , repeat the iterative steps;

[0157] When the calculation method for the physical field is transient calculation, the time step is considered N， The iterative process is:

[0158] A certain distribution point in the calculation domain of the finite element three-dimensional model of the CLCC converter satisfies , repeat the iterative steps;

[0159] When all distribution points in the calculation domain of the finite element three-dimensional model of the CLCC converter meet , but all time steps have not been solved, then enter the next time step and repeat the iteration steps; when all distribution points in the calculation domain of the finite element three-dimensional model of the CLCC converter meet And solve the total number of time steps N , the iterative calculation is finished, and the electric field distribution, magnetic field distribution and temperature field distribution of the i-th time are output as the final model;

[0160] Wherein, M is the voltage or current measured at each distribution point in the calculation domain of the finite element three-dimensional model of the CLCC converter; i is the number of calculations, i=2, 3…; is the relative tolerance.

[0161] like Figure 5As shown, embodiment 2 of the present invention provides a CLCC converter multi-physics field coupling modeling system, which runs the CLCC converter multi-physics field coupling modeling method described in embodiment 1, including: a three-dimensional model simplification module 1, a parameter condition setting module 2, a finite element segmentation module 3, an electromagnetic coupling simulation module 4, a temperature field distribution calculation module 5 and an iterative calculation module 6:

[0162] The three-dimensional model simplification module 1 simplifies the initial CLCC converter three-dimensional model based on the physical field to be calculated, and selects the calculation method of the physical field;

[0163] The parameter condition setting module 2 sets material parameters, boundary conditions and initial state for the simplified CLCC converter three-dimensional model;

[0164] The finite element meshing module 3 is used to perform finite element meshing and refinement on the CLCC converter three-dimensional model to form a finite element three-dimensional model of the CLCC converter;

[0165] The electromagnetic coupling simulation module 4 performs electromagnetic coupling simulation on the finite element three-dimensional model of the CLCC converter, measures the voltage or current of each distribution point in the calculation domain of the finite element three-dimensional model of the CLCC converter; and calculates the electric displacement vector and magnetic field intensity vector of the CLCC converter;

[0166] The temperature field distribution calculation module 5 calculates the distribution of the temperature field of the CLCC converter according to the obtained electric field and magnetic field distribution of the CLCC converter;

[0167] The iterative calculation module 6 is used to update the electrical material parameters of the CLCC converter and perform iterative calculations until the calculation requirements of different calculation methods are met.

[0168] Embodiment 3 of the present invention provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the computer program is loaded into the processor, the multi-physics coupling modeling method of the CLCC converter according to Embodiment 1 is implemented.

[0169] Embodiment 4 of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and is characterized in that when the computer program is executed by a processor, the CLCC converter multi-physical field coupling modeling method according to Embodiment 1 is implemented.

[0170] In order to more clearly introduce the outstanding essential features of the present invention and the significant progress it brings to the prior art, the technical solution of the present invention is further introduced in detail below by taking the C-EPRI Purui converter as an example.

[0171] Step 1: Based on the physical field to be calculated, simplify the initial CLCC converter three-dimensional model and select the calculation method of the physical field;

[0172] The simplification and import of 3D equipment models mainly include: Figure 2 In the three-dimensional coordinate system shown in the figure, the C-EPRI Purui converter model is simplified, the bolts and their interfaces, as well as the model details such as the chamfers in the model are removed, and multiple connected metal surfaces are simplified into one metal surface. The simplified model is shown in the example Figure 3 shown.

[0173] Step 2: Set material parameters, boundary conditions and initial state for the simplified CLCC converter 3D model;

[0174] Setting material parameters, boundary conditions and initial states mainly includes: according to the CLCC topology diagram and the actual CLCC, the metal components inside the equipment are approximately regarded as ideal conductors, that is, the resistivity is set to 0; according to the material list of each position of the inverter produced by Purui Engineering, the conductivity, relative dielectric constant and magnetic permeability of each material are set. When setting, pay attention to setting each parameter as a constant of temperature. The specific method will be explained in step 5; use "metal contact" to set the input voltage at the input position of the single valve layer model; set the "tangential electric field" boundary condition at the closed metal shell position.

[0175] Step 3: According to the calculation accuracy requirement, the CLCC converter three-dimensional model is meshed and refined to form a finite element three-dimensional model of the CLCC converter;

[0176] Meshing to form a finite element model. After importing the 3D model, the meshing step begins. The basic idea of ​​the finite element method is to discretize the structure, that is, to discretize the continuum, use simplified geometric units to approximate the continuum, and then comprehensively solve it according to the deformation coordination conditions. Therefore, the division of the finite element mesh must consider the accurate description of the geometric shape of each object on the one hand, and the accurate description of the deformation gradient on the other hand. For example Figure 4 Taking the single converter valve model shown in the figure as an example, a smaller mesh size is used at the corners and intermediate gaps to obtain more accurate simulation results and better convergence.

[0177] Step 4: Perform electromagnetic coupling simulation on the finite element three-dimensional model of the CLCC converter, measure the voltage or current of each distribution point in the calculation domain of the finite element three-dimensional model of the CLCC converter; and calculate the electric displacement vector of the CLCC converter and the magnetic field strength vector ;

[0178] Solve Maxwell's equations and calculate electromagnetic field quantities. Set the relative tolerance to , and solve the Maxwell equations. Once the system is discretized and boundary conditions are imposed, a system of equations can be obtained according to the following expression:

[0179] ,

[0180] is called the stiffness matrix, is the original function matrix. Use the super-relaxation method to iteratively solve, and stop the calculation after the error converges to less than the tolerance, and get the electromagnetic field quantity The value of is then obtained according to the constitutive relationship and The value of .

[0181] Step 5: Calculate the distribution of the temperature field of the CLCC converter according to the electric field and magnetic field distribution of the CLCC converter obtained in step 4;

[0182] Then the temperature field is calculated. According to the electromagnetic field solution, the generated heat is calculated and expressed as the following formula:

[0183] (5)

[0184] Using the COMSOL Heat Transfer Module, Q Set it as a heat source, and use COMSOL to calculate its temperature rise and heat transfer, and solve for the temperature distribution inside the device .

[0185] Step 6: According to the temperature field distribution obtained in step 5, update the electrical material parameters of the CLCC converter, and return to step 4 for iterative calculation until the calculation requirements of different calculation methods are met.

[0186] According to the temperature distribution, new material parameter variables are obtained according to the above material parameter-temperature relationship. The updated electrical material parameters are used to recalculate, and the difference between the calculated result and the previous calculated result is compared with the relative tolerance. If it is less than the relative tolerance, the model reaches a steady state and the calculation ends. If it is greater than the relative tolerance, the iterative steps are repeated until convergence.

[0187] The beneficial effects of the present invention are as follows:

[0188] (1) Comprehensive electromagnetic thermal field coupling modeling: This paper conducts comprehensive electromagnetic thermal field coupling modeling of CLCC converter valves for the first time, effectively filling the gap in the field of CLCC numerical simulation. This comprehensive modeling method can accurately calculate and reflect the distribution of various physical quantities inside the CLCC converter valve, thus providing an important scientific basis for the design, operation and maintenance of the CLCC converter valve.

[0189] (2) Comprehensive coupling of electromagnetic and thermal fields: This invention is the first to comprehensively couple the electric field, magnetic field and thermal field in the calculation and analysis of CLCC. Compared with the previous single-field simulation, this method more comprehensively reflects the actual operating status of CLCC. It solves the problem of multi-field coupling analysis, thereby providing more accurate technical support for the safe operation of the controllable commutation converter CLCC.

[0190] In summary, the present invention provides a more comprehensive and accurate solution in the modeling and simulation of CLCC converters, which not only improves the scientificity and reliability of converter design, but also provides strong technical support for its safe and efficient operation.

[0191] The present disclosure may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0192] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A multi-physics coupling modeling method for CLCC converters, used in high-voltage DC multi-infeed systems, characterized in that: The following steps are involved: Based on the physical fields to be calculated, including electric field, magnetic field and thermal field, the initial CLCC converter 3D model is simplified, and steady-state calculation or transient calculation is selected; simplifying the CLCC converter 3D model includes: simplifying the bolts, threads and various material joints in the CLCC converter 3D model; omitting the completely shielded conductor interior, indicator lights and color and texture information in the CLCC converter 3D model from the model; simplifying the chamfers and bevels in the CLCC converter 3D model; Set material parameters, boundary conditions and initial state for the simplified CLCC converter 3D model; Performing finite element meshing and refinement on the CLCC converter three-dimensional model to form a finite element three-dimensional model of the CLCC converter; Performing electromagnetic coupling simulation on the finite element three-dimensional model of the CLCC converter, measuring the voltage or current of each distribution point in the calculation domain of the finite element three-dimensional model of the CLCC converter; and calculating the electric displacement vector and magnetic field intensity vector of the CLCC converter; According to the obtained electric field and magnetic field distribution of the CLCC converter, the distribution of the temperature field of the CLCC converter is calculated; According to the obtained temperature field distribution, the electrical material parameters of the CLCC converter are updated, and the electromagnetic coupling simulation step is returned to perform iterative calculations until the calculation requirements of different calculation methods are met.

2. The multi-physics coupling modeling method for CLCC converter according to claim 1, characterized in that: In the calculation process of different physical fields, the principle of minimum simplification is followed, and any element that cannot be simplified in any physical field must be retained. For all physical fields, the simplified CLCC converter three-dimensional model is the same.

3. A CLCC converter multi-physics field coupling modeling method according to claim 1, characterized in that: When the DC side physical field is calculated first, steady-state calculation is used; when the AC side physical field is calculated first, transient calculation is used.

4. A CLCC converter multi-physics field coupling modeling method according to claim 1 or 2, characterized in that: Setting material parameters for the simplified CLCC converter three-dimensional model includes: setting corresponding initial conductivity, magnetic permeability and heat transfer coefficient according to material information used by the CLCC converter; The boundary conditions for the simplified CLCC converter three-dimensional model are as follows: for electrostatic field simulation, the voltage boundary conditions and open boundary conditions need to be set according to the actual working conditions of the CLCC converter; in magnetic field simulation, the current boundary conditions and open boundary conditions are set according to the actual working conditions of the CLCC converter and the ports with actual known current input values; for thermal field simulation, the temperature conduction boundary conditions are set according to the operating environment of the CLCC converter; the actual working conditions of the CLCC converter refer to the normal, faulty, DC and AC working conditions of the CLCC; the actual operating environment of the CLCC converter refers to the temperature and humidity of the gate chamber when the CLCC equipment is running; Setting the initial state of the simplified CLCC converter three-dimensional model includes: setting the actual ambient temperature, initial electric field and initial magnetic field of the CLCC converter.

5. A CLCC converter multi-physics field coupling modeling method according to claim 4, characterized in that: Finite element mesh generation and refinement of the CLCC converter three-dimensional model includes: When the side length or curvature radius of the CLCC component r<10cm, the mesh is refined in the area L<2r, and the mesh refinement value is the maximum length of each mesh <0.2*r, where L represents the distance between each grid point and the midpoint of the straight edge of the component or the vertex of the curve.

6. A CLCC converter multi-physics field coupling modeling method according to claim 1 or 5, characterized in that: Perform electromagnetic coupling simulation on the finite element three-dimensional model of the CLCC converter, measure the voltage or current of each distribution point in the calculation domain of the finite element three-dimensional model of the CLCC converter; and calculate the electric displacement vector of the CLCC converter and the magnetic field strength vector include: Set the voltage according to the rated voltage value of CLCC in different working states and open the corresponding boundary conditions; Set the preset total simulation time T, number of time steps N, and time step size for electromagnetic coupling simulation as required and relative tolerance ,in ; Set the solution order to electromagnetic-heat transfer: Calculate the electric field strength vector and the magnetic flux density vector ; Based on the electric field strength vector and the magnetic flux density vector , the electric displacement vector is obtained by using the constitutive relationship and the magnetic field strength vector .

7. A CLCC converter multi-physics field coupling modeling method according to claim 6, characterized in that: Relative Tolerance The value is .

8. A CLCC converter multi-physics field coupling modeling method according to claim 5, characterized in that: According to the material parameters and grid distribution of the materials in the calculation area, a stiffness matrix is ​​formed ; According to the boundary conditions and the voltage and current parameters of the CLCC converter under different working conditions, a source vector matrix is ​​formed , solve the following matrix equation: （1） Get the electromotive force distribution matrix , and according to the following equation: （2） Solving for the electric field strength vector ; Use the same solution method to obtain the magnetic vector potential ; and according to Get the magnetic flux density vector .

9. A CLCC converter multi-physics field coupling modeling method according to claim 8, characterized in that: Electric displacement vector and the magnetic field strength vector The solution is shown in the following formula: （3） （4） Where: and are the dielectric constant and magnetic permeability in vacuum respectively; and are the relative dielectric constant and relative magnetic permeability of the CLCC converter material respectively.

10. A CLCC converter multi-physics field coupling modeling method according to claim 9, characterized in that: Calculation of temperature field distribution includes: Calculate the generated heat Q, expressed as follows: （5） Where: , , They are magnetic flux density vector, electric field intensity vector and magnetic field intensity vector respectively; is the total current density vector; They are the total heat, joule heat, and induced heat generated by CLCC; Re represents the real part of a complex number; Set Q as the heat source, calculate its temperature rise and heat transfer, and solve for the temperature distribution of each point in the device ; Wherein, x, y, z are the x-coordinate, y-coordinate and z-coordinate of the temperature field of the CLCC converter.

11. A CLCC converter multi-physics field coupling modeling method according to claim 10, characterized in that: Updating the electrical material parameters of the CLCC converter includes: updating the relative dielectric constant, electrical conductivity and magnetic permeability of the electrical material through the relationship between the preset initial dielectric constant, electrical conductivity, magnetic permeability and temperature.

12. A CLCC converter multi-physics field coupling modeling method according to claim 11, characterized in that: When the calculation method for the physical field is steady-state calculation, the time step number N is not considered, and the iterative process for the model voltage or current is: When all distribution points in the calculation domain of the finite element three-dimensional model of the CLCC converter meet , the iterative calculation is finished, and the electric field distribution, magnetic field distribution and temperature field distribution of the i-th time are output as the final model; When a certain distribution point in the calculation domain of the finite element three-dimensional model of the CLCC converter satisfies , repeat the iterative steps; Wherein, M is the voltage or current measured at each distribution point in the calculation domain of the finite element three-dimensional model of the CLCC converter; i is the number of calculations, i=2, 3…; is the relative tolerance.

13. A CLCC converter multi-physics field coupling modeling method according to claim 11, characterized in that: When the calculation method for the physical field is transient calculation, the number of time steps N is considered, and the iterative process is: A certain distribution point in the calculation domain of the finite element three-dimensional model of the CLCC converter satisfies , repeat the iterative steps; When all distribution points in the calculation domain of the finite element three-dimensional model of the CLCC converter meet , but all time steps have not been solved, then enter the next time step and repeat the iteration steps; when all distribution points in the calculation domain of the finite element three-dimensional model of the CLCC converter meet After solving the total number of time steps N, the iterative calculation ends, and the electric field distribution, magnetic field distribution and temperature field distribution of the ith time are output as the final model; Wherein, M is the voltage or current measured at each distribution point in the calculation domain of the finite element three-dimensional model of the CLCC converter; i is the number of calculations, i=2, 3…; is the relative tolerance.

14. A CLCC converter multi-physics field coupling modeling system, running the CLCC converter multi-physics field coupling modeling method according to any one of claims 1 to 13, comprising: Three-dimensional model simplification module, parameter condition setting module, finite element segmentation module, electromagnetic coupling simulation module, temperature field distribution calculation module and iterative calculation module; characterized in that: The 3D model simplification module simplifies the initial CLCC converter 3D model based on the physical field to be calculated and selects the calculation method of the physical field; The parameter condition setting module sets material parameters, boundary conditions and initial state for the simplified CLCC converter three-dimensional model; The finite element meshing module is used to perform finite element meshing and refinement on the CLCC converter three-dimensional model to form a finite element three-dimensional model of the CLCC converter; The electromagnetic coupling simulation module performs electromagnetic coupling simulation on the finite element three-dimensional model of the CLCC converter, measures the voltage or current of each distribution point in the calculation domain of the finite element three-dimensional model of the CLCC converter; and calculates the electric displacement vector and magnetic field intensity vector of the CLCC converter; The temperature field distribution calculation module calculates the distribution of the temperature field of the CLCC converter according to the obtained electric field and magnetic field distribution of the CLCC converter; The iterative calculation module is used to update the electrical material parameters of the CLCC converter and perform iterative calculations until the calculation requirements of different calculation methods are met.

15. A terminal comprising a processor and a storage medium; characterized in that: The storage medium is used to store instructions; The processor is used to operate according to the instructions to execute the steps of a CLCC converter multi-physics field coupling modeling method according to any one of claims 1-13.

16. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of a CLCC converter multi-physical field coupling modeling method described in any one of claims 1-13 are implemented.

Images