Three-dimensional heat-flow decoupling modeling method and device for three-phase three-axis high-temperature superconducting cable

Abstract

The invention relates to the technical field of superconducting cables, in particular to a three-dimensional heat-flow decoupling modeling method and device for a three-phase three-axis high-temperature superconducting cable, and the method comprises the steps: constructing a simplified three-phase three-axis high-temperature superconducting cable geometric model; constructing a temperature distribution finite element model, wherein the temperature distribution finite element model comprises a decoupled fluid model and a heat transfer model; the dynamic temperature distribution of the three-phase three-axis high-temperature superconducting cable under the influence of transient factors is solved by using a temperature distribution finite element model, and the method comprises the following steps: 1) a steady state step: based on an initial boundary condition, completing basic solution of a cable temperature field and a liquid nitrogen flow velocity field under a steady state through coupling calculation of a fluid module and a heat transfer module; 2) a transient step: taking a result value of steady-state solution as an initial condition of transient solution, and finally outputting a temperature distribution simulation result through multi-step transient solution iteration and flow field and temperature field distribution.Compared with the prior art, the method has the advantages of high modeling precision, small calculation amount, fast convergence and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of superconducting cables, in particular to a three-dimensional thermal-flow decoupling modeling method and device for a three-phase three-axis high-temperature superconducting cable. BACKGROUND

[0002] With the development of superconducting power technology, superconducting power devices are gradually entering the power industry. With the characteristics of zero resistance and high current-carrying density of superconductors, superconducting cables have the advantages of low loss, large capacity and small size. Compared with conventional cables, the transmission capacity of superconducting cables can be increased by 5-10 times under the same voltage level, or the same capacity can be transmitted under a lower voltage level. According to the current-carrying characteristics of superconductors, the current-carrying capacity of superconducting tapes is affected by temperature. High-temperature superconducting cables are subjected to electromagnetic thermal-flow multi-field coupling in actual operation, and the multi-field behavior is directly related to the safe and stable operation of the cable, and the coupling relationship between the magnetic field, temperature and fluid needs to be fully considered. On the one hand, the superconducting cable has very small loss (AC) or no loss (DC) under normal current conditions, but the superconducting cable must face various thermal loads in actual operation. At the same time, the low-temperature system is an important auxiliary system for the normal operation of the superconducting cable, and the refrigeration power of the low-temperature system and the flow rate of liquid nitrogen have an important influence on the operation of the system. It is of great significance to study the response of superconducting cables to endogenous thermal loads and the response characteristics of superconducting cables under different operating conditions of the low-temperature system through experiments combined with simulation methods for cable protection.

[0003] Therefore, it is necessary to accurately model the thermal-flow characteristics of high-temperature superconducting cables to predict the radial and axial temperature distribution of superconducting cables under different operating conditions. The finite element method is a numerical analysis method, the core of which is to discretize the complex solution domain into a finite number of simple geometric units, and to construct an approximate function on each unit, and to approximate the solution of the original problem by solving the equation system of these units. Since the three-phase three-axis cable does not have an axisymmetric structure, it can only be modeled in three dimensions, but a three-dimensional thermal-flow coupled model will bring problems of large calculation amount and difficulty in convergence.

[0004] After searching, Chinese invention patent application publication No. CN117494513A discloses a finite element modeling method for predicting the temperature field of a high-temperature superconducting cable channel, comprising the following steps: step 1: establishment of a geometric model, the model is given a material; step 2: adding heat source load, boundary conditions and dividing the geometric model into grids; step 3: establishing a transient temperature field analysis step. The present application can realize the finite element modeling of predicting the temperature field of a high-temperature superconducting cable. The existing patent application has the problems of large modeling calculation amount and difficulty in convergence.

[0005] How to realize three-dimensional thermal-flow decoupling modeling of a three-phase three-axis high-temperature superconducting cable has become a technical problem to be solved. SUMMARY

[0006] The present application aims to overcome the defects of the prior art and provide a three-dimensional thermal-flow decoupling modeling method and device for a three-phase three-axis high-temperature superconducting cable.

[0007] The object of the present application can be achieved by the following technical solutions: According to one aspect of the present application, a three-dimensional thermal-flow decoupling modeling method for a three-phase three-axis high-temperature superconducting cable is provided, comprising: constructing a simplified three-phase three-axis high-temperature superconducting cable geometric model; constructing a three-dimensional temperature distribution finite element model, including a decoupled fluid model and a heat transfer model; solving the dynamic temperature distribution of the three-phase three-axis high-temperature superconducting cable under the influence of transient factors using the temperature distribution finite element model, including: 1) Steady-state step: based on the initial boundary conditions, the fluid module and the heat transfer module are coupled to calculate the basic solution of the cable temperature field and the liquid nitrogen flow field under steady state; 2) Transient step: the result of the steady-state solution is taken as the initial condition for transient solution, and the flow field and temperature field distribution are updated through multi-step transient solution iteration, and finally the temperature distribution simulation result is output.

[0008] As a preferred technical solution, the fluid module and the heat transfer module are coupled to calculate, which is specifically: first, the fluid module calculates the flow field characteristics of liquid nitrogen in the Dewar tube based on the initial boundary conditions, and outputs the initial value of the flow field; then, the initial value of the flow field is substituted into the heat transfer module, and the heat balance between the cable and the liquid nitrogen is solved in combination with the heat exchange boundary conditions, and the initial value of the temperature field is output.

[0009] As a preferred technical solution, the multi-step transient solution iteration includes: setting the result of the steady-state step as a new initial value, first calling the fluid module to recalculate the flow field characteristics, and outputting the flow field distribution; then, the updated flow field distribution is fed back to the heat transfer module to recalculate the temperature field distribution; the output of the previous transient step is taken as a new initial value, and the flow field and temperature field distribution are iteratively calculated, and the iteration is continued until all transient steps are completed, and finally the temperature distribution simulation result is output.

[0010] As a preferred technical solution, the initial boundary conditions are obtained using a steady-state solver, wherein the initial boundary conditions include liquid nitrogen flow, liquid nitrogen inlet temperature and heat load.

[0011] As a preferred technical solution, the simplified three-phase three-axis high-temperature superconducting cable geometric model includes simplifying the superconducting current-carrying layer and the superconducting shielding layer into one domain, and ignoring the multi-layer structure of the conductor and its winding mode.

[0012] As a preferred technical scheme, the simplified three-phase three-axis high-temperature superconducting cable geometry model further comprises: directly adding alternating current loss as a heat source into simulation; and omitting an outer Dewar wall, and replacing a heat exchange process of liquid nitrogen passing through the outer Dewar wall with a heat exchange boundary condition.

[0013] As a preferred technical scheme, the method further comprises: generating free triangular meshes of different sizes on a radial section of the three-phase three-axis high-temperature superconducting cable, and adaptively adjusting sizes of the meshes according to structures of different layers, so as to ensure mesh quality and calculation speed.

[0014] As a preferred technical scheme, the fluid module adopts a k-ε model in a turbulent flow module to solve turbulent kinetic energy and turbulent kinetic energy dissipation rate.

[0015] As a preferred technical scheme, the control equation of the heat transfer module is as follows: , , Among them, ρ is a material density, C p is a specific heat capacity under constant pressure of the material, k is a thermal conductivity of the material, and u is a velocity field of the material domain, Q is a heat source; q is a heat flux vector, is a divergence of q, T is a temperature, t is time, is a temperature gradient.

[0016] According to another aspect of the present application, an electronic device is provided, comprising a memory and a processor, the memory having a computer program stored thereon, and the processor implementing the method when executing the program.

[0017] Compared with the prior art, the present application has the following beneficial effects: 1) The present application simplifies a geometry model of a three-phase three-axis high-temperature superconducting cable, and realizes radial and axial temperature distribution simulation of the three-phase three-axis high-temperature superconducting cable under different working conditions through decoupling of a flow field and a temperature field and step-by-step iterative calculation, so as to improve convergence and calculation speed of a three-dimensional simulation model while ensuring calculation precision.

[0018] 2) The present application generates free triangular meshes of different sizes on a radial section, sweeps the meshes to obtain meshes of the whole cable, and adjusts sizes of the meshes according to different structures, so as to ensure mesh quality and calculation speed, and thus compatibility of calculation precision and speed. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1A schematic diagram of a simplified three-phase three-axis high-temperature superconducting cable geometry model; Figure 2 A Figure 1 A schematic diagram of the structure of a single-phase high-temperature superconducting cable; Figure 3 A schematic diagram of the structure of a free triangular mesh on the radial cross-section of a three-phase three-axis high-temperature superconducting cable; Figure 4 A schematic diagram of the mass histogram of the mesh elements of a free triangular mesh; Figure 5 A schematic diagram of the workflow of a temperature distribution finite element model; Figure 6 A schematic diagram of the flow velocity distribution of a steady-state solution; Figure 7 A schematic diagram of the temperature distribution along the line of the superconducting conductor layer. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor should fall within the scope of protection of the present application.

[0021] To solve the above problems, the present application proposes a three-dimensional thermal-flow decoupling modeling method for a three-phase three-axis high-temperature superconducting cable based on finite element software, and reasonably simplifies the structure of the superconducting cable, greatly improving the convergence and calculation speed of the model while ensuring the calculation accuracy.

[0022] Embodiment 1 The present embodiment relates to a three-dimensional thermal-flow decoupling modeling method for a three-phase three-axis high-temperature superconducting cable. By decoupling the thermal-flow method and simplifying the structure of the three-dimensional model, the convergence and calculation speed of the three-dimensional simulation model are improved, while the calculation accuracy is ensured, thereby realizing the radial and axial temperature distribution calculation of the three-phase three-axis high-temperature superconducting cable under different working conditions.

[0023] The method comprises the following steps: Step one, referring to the structure of a three-phase three-axis high-temperature superconducting cable, a corresponding simplified geometric model is constructed, and mesh division is performed.

[0024] Due to the high aspect ratio characteristics of the three-dimensional model of a long-distance three-phase three-axis cable, it will bring the problems of large amount of calculation and difficulty in convergence. Decoupling the flow field and the temperature field can significantly improve the convergence of the model, improve the calculation speed, and at the same time ensure a high degree of accuracy.

[0025] Three-phase three-axis high-temperature superconducting cable adopts three single-phase cables with the same structure to form a spiral structure. Each single-phase cable adopts a multi-layer composite structure design, the center part is a copper substrate support core (referred to as copper substrate core), and the periphery is sequentially wrapped with a superconducting current-carrying layer composed of high-temperature superconducting material, an insulation layer, a superconducting shielding layer and a copper shielding layer. The whole cable body is packaged in a specially designed vacuum insulation system, which is composed of two layers of corrugated stainless steel pipes (the inner layer of stainless steel corresponds to the inner pipe, and the outer layer of stainless steel corresponds to the outer pipe, wherein the outer layer of stainless steel is the outer Dewar wall) to form a main sealed cavity, and high-performance multi-layer composite insulation materials are filled between the pipe walls to achieve excellent thermal insulation performance by maintaining a high vacuum state.

[0026] Simplify the geometric model of three-phase three-axis high-temperature superconducting cable: simplify two layers of superconducting tapes (superconducting current-carrying layer and superconducting shielding layer) into one domain, ignoring the multi-layer structure of REBCO conductor and its winding method. Since the influence of current distribution is not considered in the thermal-flow coupling simulation model, but the alternating current loss is directly added as a heat source to the simulation, this simplification will not have a significant impact on the temperature distribution results, while greatly reducing the calculation amount and shortening the calculation time. In addition, the outer Dewar wall structure is complex, and the model omits the outer Dewar wall. The heat exchange process of liquid nitrogen through the outer Dewar wall is replaced by a heat exchange boundary condition. The simplified structure of the three-phase three-axis high-temperature superconducting cable is as follows: Figure 1 , Figure 2 , Figure 1 ,

[0027] The remaining equivalent and assumptions in the modeling process are as follows: (1) Assume that the superconducting cable core is completely symmetrical and located at the center of the Dewar tube; (2) Assume that the liquid nitrogen completely fills the pipeline, and the inlet temperature is constant (such as 70K); (3) Assume that the alternating current loss is uniformly added to the superconducting current-carrying layer and the superconducting shielding layer, and the current lead heat source is added to the superconducting current-carrying layer.

[0028] Mesh partitioning: Due to the high aspect ratio of the three-phase three-axis high-temperature superconducting cable, and the size of the superconducting current-carrying layer and the superconducting shielding layer is very small, in the radial section, the size of the mesh needs to be adjusted for different structures to ensure mesh quality and calculation speed. Different sizes of free triangular meshes are generated in the radial section, and the mesh of the whole cable is obtained by sweeping, and the generated mesh is as follows: Figure 3 The corresponding mesh element quality histogram is shown in Figure 4 , where the horizontal axis represents the element quality, and the element quality gradually increases from left to right; the vertical axis is the number of elements; therefore Figure 4 , the higher the right histogram in Figure 4 , the more high-quality elements, and from it can be seen that most of the mesh elements have high quality.

[0029] For high aspect ratio structure (such as long distance cable), the cross section can be first divided by free triangular mesh, and different regions are adaptively adjusted to set different mesh sizes (such as superconducting current-carrying layer and superconducting shielding layer, etc. thin region uses very small mesh (such as 1 / 2 in thickness direction), and the insulating layer region is appropriately thickened). Thus, the adaptive mesh division can improve the convergence of model calculation, while avoiding inaccurate calculation results due to low mesh quality.

[0030] Step two, after inputting the initial boundary conditions, the steady-state flow field distribution is calculated in the turbulence module (belonging to the fluid module). Then, the flow field distribution is taken as the initial value to calculate the temperature distribution of the cable in the heat transfer module.

[0031] Thermal-flow decoupling working principle: High temperature superconducting cable is subjected to electromagnetic, thermal, fluid and other multi-field coupling in actual operation, and the multi-field behavior is directly related to the safe and stable operation of the cable, so the coupling relationship between the magnetic field, temperature and fluid should be fully considered. In this finite element model, according to the material properties, it can be divided into liquid and solid two domains. In the liquid domain of liquid nitrogen as the material, the fluid module is used to calculate the flow state of liquid nitrogen in the dewar tube, and the heat transfer module is used to calculate the temperature field to consider the heat transfer process inside and between the material domains. Since the flow velocity distribution of liquid nitrogen will affect the temperature distribution, the fluid module needs to be called in the finite element software to calculate the flow velocity distribution of liquid nitrogen in the dewar tube.

[0032] For general engineering problems, the dynamic thermal characteristics of superconducting cables under the influence of transient factors are usually solved, and this model can be used for step-by-step solution, as shown in Figure 5 First step, steady-state step: the initial boundary conditions (liquid nitrogen flow, liquid nitrogen inlet temperature, heat load, etc.) are obtained by using the steady-state solver. Based on the initial boundary conditions, the flow field characteristics of liquid nitrogen in the dewar tube are calculated by the fluid module (spf) and the heat transfer module (ht) coupling calculation. The flow field initial value is output, and then the flow field initial value is substituted into the heat transfer module. Combined with the heat exchange boundary conditions, the heat balance between the cable and the liquid nitrogen is solved, and the temperature field initial value is output, completing the basic solution of the cable temperature field and the liquid nitrogen flow velocity field under steady state, providing the initial state for subsequent transient calculation; Next, the initial conditions are set to the results of the steady-state step, that is, the initial state of each dependent variable is loaded. For transient problems that need to be solved in multiple steps, such as adding new local hot spots, changing boundary conditions, etc., further increase the transient solution step and inherit the solution results of the previous step as the initial value of the new step.

[0033] ​Second step, transient step 1: set the results of the steady-state step as new initial values, first call the fluid module (spf), consider the influence of the temperature field on the fluid properties (such as the density and viscosity of liquid nitrogen) or the characteristics of the flow channel, recalculate the flow field (update the flow rate, pressure distribution, etc.); then feed the updated flow field data back to the heat transfer module (ht) to re-solve the temperature field distribution (because the flow field changes will change the heat dissipation / heat absorption rate), output the temperature field distribution under transient step 1.

[0034] Third step, transient step 2: take the output of transient step 1 (temperature field, flow field) as new initial values, repeat the module coupling calculation logic, update the flow field and temperature field distribution.

[0035] Fourth step, continue iteration until all transient steps are completed, finally output the temperature distribution simulation results.

[0036] Example 2 This embodiment relates to a three-dimensional thermal-flow decoupling modeling method of a three-phase three-axis high-temperature superconducting cable, and takes a certain 1200 m / 35 kV / 2.2 kA three-phase three-axis high-temperature superconducting cable demonstration project as an example to explain the three-dimensional thermal-flow decoupling modeling method of the three-phase three-axis high-temperature superconducting cable.

[0037] Referring to the design parameters of the project, the key design parameters of the three-phase three-axis cable modeling finally adopted for the 1200 m, 35 kV / 2.2 kA superconducting cable modeling are shown in Table 1.

[0038] Table 1

[0039] Since the flow rate distribution of liquid nitrogen will affect the temperature distribution, it is necessary to call the fluid module in the finite element software to calculate the flow rate distribution of liquid nitrogen in the dewar tube. In order to select a suitable calculation module and control equation, the flow characteristics of liquid nitrogen need to be discussed. The general method to determine whether the liquid flow in the pipe is turbulent or laminar is to calculate the Reynolds number. The Reynolds number is a dimensionless number used to characterize the flow of a fluid, defined as the ratio of the inertial force of the fluid to the viscous force, denoted as Re.

[0040] By introducing the dynamic viscosity, the Reynolds number of liquid nitrogen in this model is calculated as follows: , (1) , (2) In the formula, v is the average flow rate of liquid nitrogen in the pipe cross section, m / s; d is the equivalent diameter of the pipe, m; ρ is the density of liquid nitrogen, kg / m 3 ; μ is the dynamic viscosity coefficient of liquid nitrogen, m2 / s; A A is the cross-sectional area, m 2 ; P P is the wetted perimeter, m.

[0041] When the Reynolds number Re is less than 2300, the viscous force has a greater impact on the flow field than the inertial force, in which case the disturbance will weaken due to the presence of viscous force, and thus the fluid flow is stable and belongs to the laminar state. In contrast, when the Reynolds number is greater than 4000, the inertial force has a greater impact on the flow field, resulting in unstable fluid flow. Small changes in flow rate enhance the degree of turbulence in the flow field, forming turbulent flow and exhibiting chaotic and irregular characteristics. The parameters in this model are shown in Table 2, and the calculated Reynolds number is 23445.7, which is much higher than the turbulent flow critical criterion of 4000, so the liquid nitrogen in the superconducting cable dewar in this project is in a turbulent flow state.

[0042] Table 2

[0043] The finite element model uses the k-ε model in the turbulence module (spf), which solves two variables: the turbulent kinetic energy k and the turbulent kinetic energy dissipation rate ε . This model can only solve the turbulent viscosity in the fully turbulent region and must be used with a wall function, sacrificing the accuracy of the solution in the near-wall region. k - ε The model has good convergence speed and relatively low memory requirements, but it cannot accurately calculate the adverse pressure gradient and strong curvature flow or jet flow field. Its control equation set is as shown in equation (3).

[0044] , (3) Where, ρ is the material density, u is the velocity field in the material domain, K is the deviatoric stress tensor, F is the body force, C μ is the turbulent viscosity constant, μ is the dynamic viscosity, μ T is the turbulent viscosity, k is the turbulent kinetic energy, P k is the turbulent energy generation term, ε is the turbulent kinetic energy dissipation rate, I is the unit tensor, is the turbulent Prandtl number of k, is the turbulent Prandtl number, and are empirical coefficients, is the proportionality constant of the turbulent viscosity, and p are the turbulent kinetic energy dissipation rate and static pressure, respectively, is the gradient, is the divergence.

[0045] In practical engineering, the low-temperature system is usually regulated by controlling the flow rate of liquid nitrogen. The design of the superconducting cable cooling system in this project is to set the flow rate of liquid nitrogen to be 2~4.2m 3 / h. By setting the flow rate of liquid nitrogen, the initial flow rate of the liquid nitrogen inlet can be calculated, and the flow rate distribution of the Dewar tube at steady state can be calculated in the fluid module.

[0046] For the calculation of the temperature field in the model domain, the solid and liquid heat transfer module (ht) needs to be called in the finite element software, and the control equation is as follows: , (4) , (5) In equation (4), ρ is the material density, C p is the specific heat capacity under constant pressure, k is the thermal conductivity of the material, u is the velocity field of the material domain, Q is the heat source, which describes the heat generation in the domain; q is the heat flux vector, is the divergence of q, T is the temperature, t is the time, is the temperature gradient.

[0047] Equation (5) is the Fourier heat conduction law, where q is the heat flux vector, is the temperature gradient, and the two are related by the thermal conductivity k of the material; For the thermal properties of different materials such as thermal conductivity and constant-pressure heat capacity, an interpolation function can be defined to represent the change with temperature. Through such a definition, the model can be more accurate and consistent with the actual situation. For the liquid domain in the model, the flow rate will affect the temperature distribution according to equation (4), and the steady-state value calculated in the turbulence module can be used as the initial value of the liquid nitrogen flow rate. After setting the thermal conductivity k of various materials in the model, the heat source Q of each region, the initial temperature, and the initial flow rate of liquid nitrogen, etc. boundary conditions, the temperature field distribution can be solved.

[0048] The initial temperature is set to 70K, the inlet flow rate is 0.14m / s, and the steady-state velocity distribution is shown in Figure 6 From Figure 6 it can be seen that the flow rate of liquid nitrogen near the wall surface is significantly reduced, which is the result of wall viscous force, while the flow rate of liquid nitrogen along the line does not change significantly. The maximum flow rate of liquid nitrogen in the Dewar tube is 0.18m / s, and the minimum flow rate appears at the center of the three-phase cable core, about 0.06m / s.

[0049] The current and temperature rise data of the actual operation of the superconducting cable show that when full load operation, the current reaches 2160.12A, and the highest temperature rise of the cable inlet and outlet line is 4.41K; when low load operation, the average current is 274A, and the average temperature rise of the cable is 2.496K. According to the experimental data, the effectiveness of the simulation model can be verified. In order to compare with the experimental data, the following is specifically analyzed for the temperature characteristics along the line when the current is 2160A and 274A.

[0050] Figure 7 For the temperature distribution along the superconducting conductor layer when the current is 2160A and 274A, the temperature rise at the end of the cable is 74.647K and 72.4K respectively in the steady state. The temperature along the superconducting cable gradually rises, and due to the influence of the heat leakage of the end current lead, the temperature rise is steep at a distance of 5m from the end. Comparing the actual test data, it can be seen that the absolute error of the simulation result when the current is 274A is 0.096K, and the relative error is 0.1%; the absolute error of the simulation result when the current is 2160A is 0.237K, and the relative error is 5%. The overall error is small, which can verify the effectiveness of the model. The simplified model is used for fluid steady-state simulation, steady-state thermal simulation and transient thermal simulation, and the simulation time is 2h54min, 9min19s and 25min18s respectively, and the convergence and calculation speed of the model are obviously improved.

[0051] In summary, through the three-dimensional thermal-flow decoupling modeling of the three-phase three-axis high-temperature superconducting cable, the calculation speed and convergence of the three-dimensional model can be greatly improved while ensuring the calculation accuracy, which has reference significance for the thermal simulation of long-distance high-temperature superconducting cables.

[0052] Example 3 The electronic device of the present application includes a central processing unit (CPU) that can perform various appropriate actions and processes in accordance with computer program instructions stored in a read-only memory (ROM) or loaded into a random access memory (RAM) from a storage unit. Various programs and data required for device operation can also be stored in the RAM. The CPU, ROM, and RAM are connected to each other via a bus. An input / output (I / O) interface is also connected to the bus.

[0053] A plurality of components in the device are connected to the I / O interface, including: an input unit such as a keyboard, a mouse, etc.; an output unit such as various types of displays, a speaker, etc.; a storage unit such as a magnetic disk, an optical disk, etc.; and a communication unit such as a network card, a modem, a wireless communication transceiver, etc. The communication unit allows the device to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0054] The processing units perform the various methods and processes described above. For example, in some embodiments, the methods can be implemented as a computer software program tangibly embodied in a machine readable medium, such as a storage unit. In some embodiments, portions of the computer program, or all of the computer program, can be loaded onto the device via, for example, the ROM and / or the communications unit. When the computer program is loaded onto the RAM and executed by the CPU, one or more of the steps of the methods described above can be performed. Alternatively, in other embodiments, the CPU can be configured to perform the methods by way of other means (e.g., via firmware).

[0055] The functionality described herein above can be performed, at least in part, by one or more hardware logic components. For example, and without limitation, illustrative types of hardware logic components that can be used include Field-programmable Gate Arrays (FPGAs), Program- specific Integrated Circuits (ASICs), Program- specific Standard Products (ASSPs), System-on-a-chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), etc.

[0056] Program code for carrying out methods of the present application can be written in any combination of one or more programming languages. This program code can be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program code, when executed by the processor or controller, causes the functions / acts specified in the flow diagrams and / or block diagrams to be implemented. The program code can be executed by the processor or controller entirely on a machine, partly on the machine, partly on a remote machine or entirely on a remote machine or server.

[0057] In the context of the present application, a machine-readable medium can be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine- readable medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine-readable storage medium will include one or more lines of a program of instructions in a searchable database, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory, an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0058] The above merely describes a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present application, and these modifications or replacements should be encompassed in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A three-dimensional thermal-flow decoupling modeling method of a three-phase three-axis high temperature superconducting cable, characterized in that, The application relates to a method for simulating the temperature distribution of a three-phase three-axis high-temperature superconducting cable. The method comprises the following steps: 1) constructing a simplified three-phase three-axis high-temperature superconducting cable geometric model; 2) constructing a three-dimensional temperature distribution finite element model, including a decoupled fluid model and a heat transfer model; 3) solving the dynamic temperature distribution of the three-phase three-axis high-temperature superconducting cable under the influence of transient factors by using the temperature distribution finite element model, including: 1) a steady-state step: based on initial boundary conditions, the fluid module and the heat transfer module are coupled to calculate, and the basic solution of the cable temperature field and the liquid nitrogen flow field under the steady state is completed; 2. The three-dimensional thermal-flow decoupling modeling method of a three-phase three-axial high-temperature superconducting cable according to claim 1, characterized in that, 2) a transient step: the result value of the steady-state solution is taken as the initial condition of the transient solution, the flow field and the temperature field distribution are updated through multi-step transient solution iteration, and finally the temperature distribution simulation result is output.

3. The three-dimensional thermal-flow decoupling modeling method of a three-phase three-axial high-temperature superconducting cable according to claim 1, characterized in that, The coupling calculation of the fluid module and the heat transfer module is specifically as follows: first, the fluid module calculates the flow field characteristics of liquid nitrogen in the Dewar tube based on the initial boundary conditions, and outputs the initial value of the flow field; then the initial value of the flow field is substituted into the heat transfer module, the heat balance between the cable and liquid nitrogen is solved in combination with the heat exchange boundary condition, and the initial value of the temperature field is output.

4. The three-dimensional thermal-flow decoupling modeling method of a three-phase three-axial high-temperature superconducting cable according to claim 1, characterized in that, The multi-step transient solution iteration comprises the following steps: the result of the steady-state step is taken as a new initial value, the flow field characteristics are recalculated by calling the fluid module first, and the flow field distribution is output; then the updated flow field distribution is fed back to the heat transfer module, and the temperature field distribution is recalculated; the output of the previous transient step is taken as a new initial value, the flow field and the temperature field distribution are iteratively calculated, and the iteration is continued until all transient steps are completed, and finally the temperature distribution simulation result is output.

5. The three-dimensional thermal-flow decoupling modeling method of a three-phase three-axial high-temperature superconducting cable according to claim 1, characterized in that, The initial boundary conditions are obtained by using a steady-state solver, wherein the initial boundary conditions include liquid nitrogen flow, liquid nitrogen inlet temperature and heat load.

6. The three-dimensional thermal-flow decoupling modeling method of a three-phase three-axial high-temperature superconducting cable according to claim 5, characterized in that, The simplified three-phase three-axis high-temperature superconducting cable geometric model comprises simplifying the superconducting current-carrying fluid layer and the superconducting shielding layer into one domain, and ignoring the multi-layer structure of the conductor and the winding mode thereof.

7. The three-dimensional thermal-flow decoupling modeling method of a three-phase three-axial high-temperature superconducting cable according to claim 1, characterized in that, The simplified three-phase three-axis high-temperature superconducting cable geometric model further comprises directly adding alternating current loss as a heat source to the simulation; the outer Dewar wall is omitted, and the heat exchange process of liquid nitrogen through the outer Dewar wall is replaced by a heat exchange boundary condition.

8. The three-dimensional thermal-flow decoupling modeling method of a three-phase three-axial high-temperature superconducting cable according to claim 1, characterized in that, The method further comprises generating free triangular grids of different sizes on the radial section of the three-phase three-axis high-temperature superconducting cable, and adaptively adjusting the size of the grid according to the structure of different layers to ensure the grid quality and the calculation speed.

9. The three-dimensional thermal-flow decoupling modeling method of a three-phase three-axial high-temperature superconducting cable according to claim 1, characterized in that, The fluid module adopts the k-epsilon model in the turbulent flow module to solve the turbulent kinetic energy and the turbulent kinetic energy dissipation rate. ， ， wherein, The control equation of the heat transfer module is as follows: is the density of the material, C p is the specific heat capacity of the material at constant pressure, k is the thermal conductivity of the material, u is the velocity field of the material domain, Q is the heat source; q is the heat flux vector, is the divergence of q, T is the temperature, t is the time, is the temperature gradient, k is the thermal conductivity.

10. An electronic device comprising a memory and a processor, said memory having stored thereon a computer program, characterized in that, The processor implements the method according to any one of claims 1-9 when executing the program.

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