State evaluation and fault early warning method and system based on superconducting current limiter modeling

Abstract

The invention discloses a state evaluation and fault early warning method and system based on superconducting current limiter modeling, an electromagnetic heat multi-physical field coupling model of a superconducting current limiter is constructed based on finite element software, and the method comprises the following steps: constructing a three-dimensional geometric structure of a solenoid-shaped superconducting current limiter, and setting a peripheral electromagnetic environment boundary; establishing an electromagnetic field control equation based on a Maxwell equation set and the nonlinear resistivity characteristic of the superconducting material, and coupling a solid heat transfer control equation to form a multi-physical field interaction model; optimizing grid division to balance calculation precision and solving efficiency; body parameters of the superconducting current limiter including the initial critical current Ic0 and the critical temperature Tc and working condition parameters including the environment temperature and the transmission current It are input, the parameters are dynamically adjusted according to the actual operation scene, and the voltage U at the two ends during normal operation is calculated through a model; by collecting voltage measured values Up at the two ends of the superconducting current limiter during actual operation in real time, whether the voltage measured values Up exceed a threshold value set according to the voltage U or not is judged, and an early warning mechanism is triggered.

Description

Technical Field

[0001] The present invention relates to the technical field of superconducting power equipment simulation and safety protection, and particularly to a method and system for state evaluation and fault early warning based on superconducting fault current limiter modeling. Background Art

[0002] With the rapid development of high-voltage direct current (HVDC) transmission technology, the power grid has put forward higher requirements for short-circuit fault protection. The short-circuit current in the DC system has no natural zero-crossing point and rises rapidly, making it difficult for traditional circuit breakers to directly interrupt. It is necessary to rely on current-limiting devices to limit the fault current to an interruptible level. Superconducting fault current limiters can perfectly solve the problem that conventional current limiters cannot balance low impedance during normal operation and high impedance during faults due to their zero-resistance characteristics and fast quench response characteristics, and become an ideal choice for DC grid protection.

[0003] In actual operation, superconducting fault current limiters not only need to cope with normal working conditions, but may also face extreme environmental conditions (such as large current shocks, strong magnetic field disturbances, or abnormal cryogenic systems). These factors will cause superconducting fault current limiters to withstand complex electromagnetic-thermal multi-physical field coupling effects, which may lead to long-term quenches or even irreversible damage.

[0004] In recent years, with the progress of digital data processing technologies (such as finite element simulation, multi-field coupling calculation, and statistical error analysis), state evaluation methods that build high-precision digital models and combine real-time monitoring data have provided new technical paths for the safety guarantee of complex power equipment. Such methods restore the multi-physical field interaction mechanism through digital modeling and use data processing technologies to quantify operation deviations, significantly improving the accuracy of state evaluation and the early warning response speed, and gradually becoming a research hotspot in the field of intelligent operation and maintenance of power equipment.

[0005] As a typical multi-physical field coupling device, the state evaluation and fault early warning of superconducting fault current limiters pose higher requirements for digital modeling accuracy and data processing capabilities - it is necessary to accurately characterize the dynamic coupling relationship of electromagnetic-thermal fields and achieve fast early warning through deviation analysis of real-time data and models. Summary of the Invention

[0006] Aiming at the defects and deficiencies of the existing superconducting fault current limiter in the state evaluation with insufficient accuracy, lagging fault early warning and easy false alarm under complex electromagnetic-thermal multi-physical field coupling conditions, the present invention provides a method and system for state evaluation and fault early warning of superconducting fault current limiters based on multi-physical field coupling modeling and hierarchical diagnosis.

[0007] The present invention achieves technological breakthroughs through the following core innovative designs: First, an electromagnetic-thermal multi-physical field coupling model of a solenoid-shaped superconducting fault current limiter is constructed based on finite element software. The three-dimensional geometric structure is constructed using the helical sweep technique and the peripheral electromagnetic environment boundaries are set. Combining Maxwell's equations, the E-J non-linear resistivity characteristics of superconducting materials, and the solid heat transfer equation forms a multi-field interaction model, and adaptive mesh division is used to balance the calculation accuracy and efficiency. Second, the body parameters of the superconducting fault current limiter (initial critical current, critical temperature) and the operating condition parameters (ambient temperature, transmission current) are input, and the parameters are dynamically adjusted to be compatible with different operating scenarios, and the normal operating voltage is calculated as the evaluation benchmark. Finally, the operating voltage is collected in real time and a hierarchical diagnosis mechanism of "threshold comparison (measured voltage value > 1.05 times the model calculated value) triggers a preliminary warning + root mean square error (RMSE) analysis to confirm the fault" is used, significantly reducing the false alarm rate and shortening the warning response time to the millisecond level.

[0008] By combining multi-physical field coupling modeling with data-driven hierarchical early warning, the present invention provides high-precision state evaluation and reliable fault early warning capabilities for superconducting fault current limiters, effectively ensuring the safe operation of equipment and power grids, while reducing maintenance costs, and is applicable to the protection requirements of high-voltage DC transmission systems.

[0009] The present invention specifically adopts the following technical solutions:

[0010] A state evaluation and fault early warning method based on superconducting fault current limiter modeling:

[0011] Construct an electromagnetic-thermal multi-physical field coupling model of a superconducting fault current limiter based on finite element software, including:

[0012] Construct the three-dimensional geometric structure of a solenoid-shaped superconducting fault current limiter and set the peripheral electromagnetic environment boundaries;

[0013] Establish an electromagnetic field control equation based on Maxwell's equations and the non-linear resistivity characteristics of superconducting materials, and couple the solid heat transfer control equation to form a multi-physical field interaction model;

[0014] Optimize the mesh division to balance the calculation accuracy and solution efficiency;

[0015] Input the body parameters of the superconducting fault current limiter including the initial critical current I c0 and the critical temperature T c and the operating condition parameters including the ambient temperature and the transmission current I t and dynamically adjust the parameters according to the actual operating scenario, and calculate the voltage U at both ends during normal operation through the model;

[0016] By collecting the measured voltage value U p at both ends of the superconducting fault current limiter during actual operation in real time, determine whether it exceeds the threshold set according to the voltage U, and trigger the early warning mechanism.

[0017] Further, by calculating the root mean square error RMSE between the measured voltage value U within the time period Δt and the voltage U calculated by the model, if RMSE > RMSE p where RMSE -th is the preset voltage error threshold, a fault warning signal is issued. -th

[0018] Further, the three-dimensional geometric structure is constructed by the helical sweeping technique, and the peripheral electromagnetic environment boundary is a cylindrical air domain.

[0019] Further, the optimized mesh division is specifically as follows: dense cells are set along the edge of the superconducting fault current limiter, and sparse meshes are used in the external air domain.

[0020] Further, in the electromagnetic-thermal multi-physical field coupling model, the non-linear resistivity of the superconducting material and the current density satisfy the E-J exponential relationship, and the critical current density varies dynamically with the magnetic field component; specifically including:

[0021] Non-linear resistivity model: Based on the E-J exponential relationship, the resistivity ρ HTS is associated with the magnitude of the current density J nom and the magnetic field-dependent critical current density J c (B).

[0022] Magnetic field-dependent critical current density model: J c (B) is jointly determined by the parallel magnetic field component B par and the perpendicular magnetic field component B per , and the inhibitory effect of the magnetic field on the critical current density is characterized by an empirical formula;

[0023] The model parameters including the electric field threshold and non-linear exponent in the E-J exponential relationship, as well as the fitting parameters in the magnetic field-dependent model, are determined according to the characteristics of the superconducting material and experimental data to achieve the dynamic coupling of the electromagnetic-thermal multi-physical fields.

[0024] Further, in the electromagnetic-thermal multi-physical field coupling model, the critical current density of the superconducting material and the temperature satisfy an empirical relationship: when the temperature T is lower than the critical temperature T c , the critical current density J c (T) decays exponentially with the increase of temperature; when T ≥ Tc, the critical current density drops to 0;

[0025] The temperature-dependent model characterizes the inhibitory effect of temperature on the critical current density by an empirical formula, and the model parameters including the initial temperature T0 and the temperature influence exponent α are determined according to the characteristics of the superconducting material and experimental data to achieve the dynamic coupling of the temperature field and the electromagnetic field.

[0026] ​Further, the voltage U is obtained by integrating the electric field strength E along the current path.

[0027] Further, the threshold value set according to the voltage U is 1.05 times the voltage U.

[0028] In addition, a state evaluation and fault warning system based on superconducting fault current limiter modeling includes:

[0029] A modeling module: used to construct an electromagnetic-thermal multi-physical field coupling model of the superconducting fault current limiter based on finite element software. The model includes a solenoid-shaped three-dimensional geometric structure, the boundary of the peripheral electromagnetic environment, the coupling equation of the electromagnetic field and solid heat transfer, and the optimized mesh division;

[0030] A parameter input module: used to input the body parameters of the superconducting fault current limiter including the initial critical current I c0 and the critical temperature T c , and the operating condition parameters including the ambient temperature and the transmission current I t , and dynamically adjust the parameters according to the actual operation scenario;

[0031] A voltage calculation module: used to calculate the voltage U at both ends of the superconducting fault current limiter during normal operation through the model;

[0032] A monitoring module: used to collect the measured voltage value U at both ends of the superconducting fault current limiter during actual operation in real time p ;

[0033] An evaluation and warning module: used to determine whether U p exceeds the threshold value set based on U and trigger the warning mechanism; and calculate the root mean square error RMSE between the measured voltage value U p and the voltage U calculated by the model within the time period of Δt. If RMSE>RMSE -th , where RMSE -th is the preset voltage error threshold, then a fault warning signal is issued.

[0034] In addition, an electronic device includes a memory, a processor, and a computer program stored on the memory and executable on the processor. The characteristic is that when the processor executes the program, the steps of the above method are implemented.

[0035] A non-transitory computer-readable storage medium stores a computer program. The characteristic is that when the computer program is executed by a processor, the steps of the above method are implemented.

[0036] Compared with the prior art, the present invention and its preferred solutions at least include the following beneficial effects:

[0037] High-precision Evaluation and Reliable Early Warning: By constructing an electromagnetic-thermal multi-physical field coupling model and combining a hierarchical early warning mechanism, high-precision state evaluation of superconducting fault current limiters under complex working conditions (such as large current surges, strong magnetic field disturbances, or abnormal low temperatures) has been achieved. The model integrates Maxwell's equations, the non-linear resistivity characteristics of superconducting materials, and the solid heat transfer equation, accurately reflecting the dynamic coupling relationship of the electromagnetic-thermal fields. At the same time, a dual-criterion logic of "threshold comparison (measured voltage > 1.05 times the model-calculated voltage triggers a preliminary warning) + root mean square error (RMSE) analysis to confirm faults" is adopted, effectively reducing the false alarm rate of faults and shortening the early warning response time, providing reliable protection for the safe operation of equipment and the power grid.

[0038] Dynamic Parameter Adjustment to Improve Multi-scenario Adaptability: The model parameters can be dynamically adjusted according to the actual operating scenarios (such as the initial critical current and critical temperature of the body parameters, the ambient temperature and transmission current of the operating conditions parameters), significantly improving the compatibility of the method with different operating conditions and supporting the continuous and reliable evaluation of superconducting fault current limiters during the transient and steady-state processes of the power system.

[0039] Geometric Construction and Mesh Optimization to Balance Precision and Efficiency: The spiral sweep technique is used to construct a solenoid-shaped three-dimensional geometric structure and set the boundary of the peripheral electromagnetic environment. Combined with adaptive mesh division (dense in key areas and sparse in the air domain), while ensuring the calculation precision, the solution efficiency is optimized, balancing the model complexity and engineering practicability.

[0040] Material Property Model to Strengthen the Authenticity of Multi-field Coupling: By introducing the E-J exponential relationship of the non-linear resistivity of superconducting materials and the critical current density model dependent on magnetic field / temperature, the quench characteristics of superconducting fault current limiters under multi-field coupling are more realistically simulated, providing a more practical theoretical basis for state evaluation. Description of the Drawings

[0041] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments:

[0042] Figure 1 This is the construction and flowchart of the embodiment scheme of the present invention. Specific Embodiments

[0043] In the following, specific embodiments of the present application will be described in detail with reference to the drawings. According to these detailed descriptions, those skilled in the art can clearly understand the present application and can implement the present application. Without violating the principles of the present application, the features in different specific embodiments can be combined to obtain new implementation manners, or some features in certain embodiments can be replaced to obtain other preferred implementation manners.

[0044] To make the features and advantages of the present invention more obvious and understandable, specific embodiments are given below and described in detail in conjunction with the drawings as follows:

[0045] The object of the present invention is to propose a new solution for superconducting fault current limiter modeling, state evaluation and fault warning in view of the problems existing in the background art.

[0046] This solution calculates the voltage U during normal operation under working conditions by establishing an electromagnetic-thermal coupling model of the superconducting fault current limiter. The actual operating voltage U is collected in real time p , and the operating state of the superconducting fault current limiter is evaluated. When U p > the given threshold, such as 1.05U, the warning mechanism is triggered, and the fault state is further judged by root mean square error analysis to achieve fault warning. As Figure 1 shown, the main steps adopted in this solution include:

[0047] Step 1: Build an electromagnetic-thermal multi-physical field coupling model of the superconducting fault current limiter based on finite element software. The specific modeling process includes: First, establish a three-dimensional geometric model of the solenoid-shaped superconducting fault current limiter, and set a sufficiently large cylindrical air domain as the calculation boundary; Second, construct the electromagnetic field control equation based on Maxwell's equations and the E-J characteristics of superconducting materials, and establish a multi-physical field coupling model in combination with the solid heat transfer control equation; Finally, perform adaptive mesh division on the model to optimize the solution efficiency while ensuring the calculation accuracy.

[0048] Step 2: Input the body parameters of the superconducting fault current limiter and the operating parameters under working conditions into the model. According to the material characteristics of the superconducting fault current limiter, input the initial critical current I c0 and the critical temperature T c . Under working conditions, the initial ambient temperature of the superconducting fault current limiter is usually 77 K, and the transmission current I t needs to be set according to the actual operating conditions of the superconducting fault current limiter.

[0049] Step 3: Calculate the voltage U across the superconducting fault current limiter during normal operation under working conditions through the model, and obtain the response relationship of U with time. The voltage U across the superconducting fault current limiter can be obtained by integrating the electric field strength along the current path.

[0050] Step 4: Collect the voltage U across the superconducting fault current limiter during actual operation in real time p , and evaluate the operating state of the superconducting fault current limiter. If U p ≤1.05U, the superconducting fault current limiter is in a normal state; if U p >1.05U, the superconducting fault current limiter may be in a fault state, and the fault warning mechanism is triggered.

[0051] Step 5: Calculate the root mean square error (RMSE) between the measured value (U p ) and the model calculated value (U) of the voltage across the superconducting fault current limiter within △t time.

[0052] Step 6: Determine whether a fault warning needs to be executed by comparing the RMSE value with the threshold RMSE-th. If the root mean square error RMSE of the measured voltage across the superconducting fault current limiter is less than or equal to the voltage error threshold RMSE-th, the superconducting fault current limiter does not need to execute a fault warning; if the root mean square error RMSE of the measured voltage across the superconducting fault current limiter is greater than the voltage error threshold RMSE-th, the superconducting fault current limiter issues a fault warning signal.

[0053] The following provides a more detailed introduction to the solution of the present invention through specific embodiments:

[0054] In the embodiment of the present invention, an electromagnetic-thermal multi-physical field coupling model of the superconducting fault current limiter is built based on finite element software. The body parameters and operating condition parameters of the superconducting fault current limiter are accurately input, and the voltage U across the two ends during normal operation under the operating conditions is calculated. The actual operating voltage U is collected in real time p , and the state of the superconducting fault current limiter is evaluated by comparing the values of U and U p . When U p > 1.05U, the warning mechanism is triggered. Further, the root mean square error (RMSE) between the measured voltage value and the model value is calculated. Through comparative analysis with the error threshold RMSE-th, fault determination and warning are realized, which specifically includes the following steps:

[0055] Step 1: Build an electromagnetic-thermal multi-physical field coupling model of the superconducting fault current limiter based on finite element software, which mainly includes three parts: geometric model construction, numerical model construction, and mesh generation.

[0056] For geometric model construction, first, the cross-section is constructed according to the size of the superconducting fault current limiter. Then, a helical spine is established. Finally, the cross-section is swept along the spine at a certain angle to obtain a three-dimensional geometric model of the solenoid-shaped superconducting fault current limiter. In addition, in order to present the complete electromagnetic environment around the superconducting fault current limiter, a large cylindrical air region needs to be set outside it.

[0057] For numerical model construction, mainly couple the electromagnetic module and the solid heat transfer module to simulate the multi-physical field coupling characteristics of the superconducting fault current limiter. The control equation of the electromagnetic module obtained based on Maxwell's equations is as follows:

[0058] (1)

[0059] where H represents the magnetic field strength, E represents the electric field strength, J represents the current density, and μ0 and μ r represent the vacuum permeability and relative permeability.

[0060] According to Ohm's law, the relationship between the electric field strength E and the current density J is:

[0061] (2)

[0062] Among them, ρ represents the resistivity. In the model, the resistivity of the air region is set to 1, and the non-linear resistivity ρ of the superconducting fault current limiter HTS satisfies the E-J exponential relationship:

[0063] (3)

[0064] Among them, E0 = 1×10 -4 V / m, n = 30, , and the critical current density J related to the magnetic field c (B) can be represented by the magnetic field component B parallel to the superconducting fault current limiter par and the magnetic field component B perpendicular to the superconducting tape fault current limiter per as follows:

[0065] (4)

[0066] Among them, J c0 is the critical current density of the self-field at liquid nitrogen temperature, k = 0.0605, b = 0.758, B c = 0.103T.

[0067] The temperature variable is introduced through the solid heat transfer module to reflect the temperature change caused by the joule heat generated by the superconducting fault current limiter, and the temperature change will in turn affect the critical current of the superconducting fault current limiter. The temperature-dependent function of the critical current density is as follows:

[0068] (5)

[0069] Among them, T c is the critical temperature of the superconducting fault current limiter; T0 is the initial temperature of the superconducting fault current limiter, T0 = 77 K. α characterizes the influence of temperature on the critical current, usually taking 1 - 2.

[0070] The control equation of the solid heat transfer model is as follows:

[0071] (6)

[0072] Among them, ρ0 represents density, C p represents specific heat capacity, k0 represents thermal conductivity, and P loss is the heat source power generated by the transmitted current.

[0073] For mesh division, as a preferred solution of this embodiment, it is necessary to first perform mesh division on the superconducting fault current limiter and ensure that there are enough elements along the edge; secondly, perform mesh division on the larger external air region. This mesh order can effectively optimize the mesh quality and improve the calculation efficiency and convergence of the model.

[0074] Step 2: Input the body parameters and operating condition parameters of the superconducting fault current limiter into the model. The body parameters include the intrinsic characteristics of the superconducting material: the initial critical current I c0 represents the superconducting current threshold without the influence of external magnetic fields under nominal cooling conditions; the critical temperature T c is the transition temperature at which the material loses its superconducting properties. The operating condition parameters need to set the initial ambient temperature of the superconducting fault current limiter to the liquid nitrogen temperature range (77 K); the transmitted current I t needs to be set according to the actual operating conditions of the superconducting fault current limiter. These parameters are usually input in the form of material properties or boundary conditions and achieve the coupling of electromagnetic, thermal, and multi-physical fields.

[0075] Step 3: Calculate the voltage U at both ends of the superconducting fault current limiter during normal operation under the operating conditions through the model, and obtain the response relationship of the voltage U with time. The voltage U at both ends of the superconducting fault current limiter is obtained by integrating the electric field strength E along the current path l:

[0076] (7).

[0077] Step 4: Real-time collect the voltage U at both ends of the superconducting fault current limiter during actual operation p to evaluate the operating state of the superconducting fault current limiter. If U p ≤1.05U, the superconducting fault current limiter is in a normal state; if U p >1.05U, the superconducting fault current limiter may be in a fault state, triggering the fault warning mechanism.

[0078] Step 5: Calculate the root mean square error (RMSE) between the measured value (U ) of the voltage at both ends of the superconducting fault current limiter and the model calculation value (U) within the p time. The calculation formula of RMSE is:

[0079] (8)

[0080] where n is the number of data acquisition points.

[0081] Step 6: Determine whether to execute the fault warning by comparing the size of the RMSE value with the threshold RMSE-th. The voltage error threshold RMSE-th of the superconducting fault current limiter is affected by various factors such as the characteristics of the superconducting material, specific operating conditions, and system safety requirements, and needs to be set according to the actual situation and requirements.

[0082] If the root mean square error RMSE of the measured value of the voltage at both ends of the superconducting fault current limiter is less than or equal to the voltage error threshold RMSE-th, the superconducting fault current limiter does not need to execute the fault warning; if the root mean square error RMSE of the measured value of the voltage at both ends of the superconducting fault current limiter is greater than the voltage error threshold RMSE-th, the superconducting fault current limiter issues a fault warning signal.

[0083] The key innovations in the above design of this embodiment at least include:

[0084] 1. Multi-physics field coupling modeling method for superconducting fault current limiter

[0085] Establish an electromagnetic-thermal multi-physics field coupling model for the superconducting fault current limiter through finite element analysis, specifically including: constructing the three-dimensional geometric structure of the solenoid-shaped superconducting fault current limiter using the spiral sweep technique and setting the cylindrical air domain boundary; establishing the electromagnetic field control equation based on Maxwell's equations combined with the E-J characteristics of superconducting materials, and coupling the solid heat transfer control equation to form a multi-physics field interaction numerical model; finally, achieving the optimal balance between calculation accuracy and solution efficiency through the adaptive mesh refinement technique.

[0086] 2. Input of operating condition parameters and dynamic coupling

[0087] By inputting the body parameters (critical current I c0 , critical temperature T c ) of the superconducting fault current limiter and the operating condition parameters (ambient temperature 77 K, transmission current I t ), realize the compatibility analysis of multiple scenarios, and characterize the dynamic coupling characteristics among current, magnetic field, and temperature in real time based on the electromagnetic-thermal coupling equation.

[0088] 3. Method for evaluating the state of superconducting fault current limiter

[0089] During the operation of the superconducting fault current limiter, the actual voltage U p at both ends is collected in real time and compared with the model calculated value U to evaluate the operating state of the superconducting fault current limiter. If U p ≤ 1.05U, the superconducting fault current limiter is in a normal state; if U p > 1.05U, the superconducting fault current limiter may be in a fault state, triggering the fault warning mechanism.

[0090] 4. Fault warning mechanism for superconducting fault current limiter

[0091] After the fault warning mechanism of the superconducting fault current limiter is triggered, further calculate the root mean square error RMSE between the measured voltage value U within the time p and the model calculated value U, and determine the error threshold RMSE-th. By comparing the RMSE value with the threshold RMSE-th, judge whether it is necessary to execute the fault warning. If the root mean square error RMSE of the measured voltage at both ends of the superconducting fault current limiter is less than or equal to the voltage error threshold RMSE-th, the superconducting fault current limiter does not need to execute the fault warning; if the root mean square error RMSE of the measured voltage at both ends of the superconducting fault current limiter is greater than the voltage error threshold RMSE-th, the superconducting fault current limiter issues a fault warning signal.

[0092] The following remarkable technical effects have been achieved:

[0093] 1. Through the electromagnetic-thermal multi-physical field coupling model, high-precision simulation of the superconducting fault current limiter under complex working conditions has been realized, and the modeling error can be controlled within 5%, providing a reliable theoretical basis for state estimation and fault warning.

[0094] 2. Innovatively combining threshold comparison (Up>1.05U) with RMSE analysis, hierarchical diagnosis from preliminary state assessment to fault confirmation has been achieved, significantly reducing the false alarm rate of faults and shortening the warning response time to the millisecond level.

[0095] 3. The model parameters can be dynamically adjusted to be compatible with different operating conditions, and the evaluation reliability can be maintained during both the transient and steady-state processes of the power system.

[0096] 4. By accurately judging the operating state of the superconducting fault current limiter and giving early warnings in a timely manner, it is possible to effectively reduce operation interruptions and equipment damage caused by quench or faults, providing guarantee for the safe operation of the superconducting fault current limiter and the power grid, and reducing maintenance and operation costs.

[0097] Based on the same inventive concept, the present invention also provides a computer device, which includes: one or more processors, and a memory for storing one or more computer programs; the program includes program instructions, and the processor is used to execute the program instructions stored in the memory. The processor may be a Central Processing Unit (CPU), or may also be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, and is used to implement one or more instructions, specifically for loading and executing one or more instructions in the computer storage medium to implement the above method.

[0098] It should be further noted that, based on the same inventive concept, the present invention also provides a computer storage medium, on which a computer program is stored. When the computer program is run by a processor, it executes the above method. The storage medium can be any combination of one or more computer-readable media. The computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. The computer-readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, infrared, or semiconductor system, apparatus, or device, or any combination of the above. More specific examples (non-exhaustive list) of the computer-readable storage medium include: an electrical connection with one or more wires, a portable computer disk, 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 disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present invention, the computer-readable storage medium can be any tangible medium that contains or stores a program, and this program can be used by or in combination with an instruction execution system, apparatus, or device.

[0099] In the description of this specification, the description with reference to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0100] The above has shown and described the basic principles, main features, and advantages of the present disclosure. Those skilled in the art should understand that the present disclosure is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present disclosure. Without departing from the spirit and scope of the present disclosure, the present disclosure will have various changes and improvements, and these changes and improvements all fall within the scope of the present disclosure claimed.

[0101] The present invention is not limited to the above best implementation manner. Anyone can obtain other various forms of state evaluation and fault warning methods and systems based on superconducting fault current limiter modeling under the inspiration of the present invention. All equal changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope covered by the present invention.

Claims

1. A method for state assessment and fault warning based on the modeling of a superconducting fault current limiter, characterized in that: Construct an electromagnetic-thermal multi-physics field coupling model of the superconducting fault current limiter based on finite element software, including: Construct the three-dimensional geometric structure of the solenoid-shaped superconducting fault current limiter and set the boundary of the peripheral electromagnetic environment; Establish an electromagnetic field control equation based on Maxwell's equations and the non-linear resistivity characteristics of superconducting materials, and couple the solid heat transfer control equation to form a multi-physics field interaction model; Optimize the mesh division to balance the calculation accuracy and solution efficiency; The input includes the initial critical current I c0 and the critical temperature T c of the superconducting fault current limiter, as well as the operating condition parameters including the ambient temperature and the transmitted current I t and dynamically adjusts the parameters according to the actual operation scenario, and calculates the voltage at both ends during normal operation through model calculation U ; By collecting the actual measured voltage values at both ends of the superconducting fault current limiter during real-time operation U p , it is determined whether it exceeds the threshold set according to the voltage U to trigger the early warning mechanism.

2. The state evaluation and fault warning method based on superconducting fault current limiter modeling according to claim 1, wherein: By calculating Δt the measured voltage value within a certain time U p and the voltage of the model calculation value U of the root mean square error RMSE , if RMSE >RMSE -th , where RMSE -th is the preset voltage error threshold, then a fault warning signal is issued.

3. A state evaluation and fault warning method based on superconducting fault current limiter modeling according to claim 1, characterized in that: The three-dimensional geometric structure is constructed by spiral sweeping technology, and the peripheral electromagnetic environment boundary is a cylindrical air domain.

4. A state evaluation and fault warning method based on superconducting fault current limiter modeling according to claim 1, characterized in that: The specific optimization of the mesh division is: set dense elements along the edge of the superconducting fault current limiter and use sparse meshes in the external air domain.

5. The method for state assessment and fault warning based on the modeling of a superconducting fault current limiter according to claim 1, characterized in that: In the electromagnetic-thermal multi-physics field coupling model, the non-linear resistivity of the superconducting material and the current density satisfy the E-J exponential relationship, and the critical current density changes dynamically with the magnetic field component; specifically including: Nonlinear resistivity model: Based on the E-J exponential relationship, the resistivity ρ HTS is associated with the magnitude of the current density J nom and the magnetic field-dependent critical current density J c (B) ; Magnetic field-dependent critical current density model: J c (B) Determined jointly by the parallel magnetic field component B par and the perpendicular magnetic field component B per The inhibitory effect of the magnetic field on the critical current density is characterized by an empirical formula; The model parameters including the electric field threshold and non-linear exponent in the E-J exponential relationship, as well as the fitting parameters in the magnetic field dependence model, are determined according to the characteristics of the superconducting material and experimental data to achieve the dynamic coupling of the electromagnetic-thermal multi-physics fields.

6. The method for state assessment and fault warning based on the modeling of a superconducting fault current limiter according to claim 1, characterized in that: In the electromagnetic-thermal multi-physical field coupling model, the critical current density of the superconducting material and the temperature satisfy an empirical relationship: when the temperature T is lower than the critical temperature T c , the critical current density J c (T) exponentially decays with the increase of temperature; when T≥Tc , the critical current density drops to 0. The temperature-dependent model characterizes the inhibitory effect of temperature on the critical current density through an empirical formula, including the initial temperature T 0 and the temperature influence index α The model parameters are determined according to the superconducting material characteristics and experimental data to achieve the dynamic coupling of the temperature field and the electromagnetic field.

7. A state evaluation and fault warning method based on superconducting fault current limiter modeling according to claim 1, characterized in that: The voltage U is obtained by integrating the electric field strength E along the current path.

8. A state evaluation and fault warning method based on superconducting fault current limiter modeling according to claim 1, characterized in that: The threshold value set according to the voltage U is 1.05 times the voltage U .

9. A state evaluation and fault warning system based on the modeling of a superconducting fault current limiter, characterized in that Including: A modeling module: used to construct an electromagnetic-thermal multi-physics field coupling model of the superconducting fault current limiter based on finite element software, the model including a solenoid-shaped three-dimensional geometric structure, a peripheral electromagnetic environment boundary, an electromagnetic field and solid heat transfer coupling equation, and an optimized mesh division; Parameter input module: used to input the body parameters of the superconducting fault current limiter including the initial critical current I c0 and the critical temperature T c as well as the operating condition parameters including the ambient temperature and the transmission current I t and dynamically adjust the parameters according to the actual operation scenario; Voltage calculation module: used to calculate the voltage across the superconducting fault current limiter during normal operation through the model U ; Monitoring module: used to collect the actual measured voltage values at both ends of the superconducting fault current limiter during actual operation in real time U p ; Evaluation and early warning module: used to determine U p whether it exceeds the U set threshold and trigger the early warning mechanism; And calculate Δt The measured voltage value within the time U p And the voltage of the model calculation value U Of the root mean square error RMSE , If RMSE>RMSE -th , Among them, RMSE -th Is the preset voltage error threshold, then a fault warning signal is issued.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method for superconducting fault current limiter state assessment and fault warning described in any one of claims 1-8.

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