High-voltage transmission line lightning stroke transient analysis method and system

Abstract

The invention provides a lightning stroke transient analysis method and system for a high-voltage power transmission line. The method comprises the following steps: acquiring power transmission line parameters, material electromagnetic parameters and atmosphere lightning stroke channel parameters; acquiring a three-dimensional electromagnetic field partial differential model and performing space-time discretization based on the three-dimensional electromagnetic field partial differential model and a plurality of preset data to acquire electric field intensity, current density and magnetic field intensity; obtaining structural material parameters; acquiring simulation voltage data and simulation current data based on the data and a plurality of preset data; acquiring actually measured data, and calculating a rise time error, a wave crest amplitude error and a high-frequency component amplitude-frequency response error based on the three data; and if the preset convergence condition is met, realizing accurate simulation of the lightning stroke transient process of the high-voltage transmission line. According to the lightning stroke transient analysis method for the high-voltage transmission line, high-precision global simulation can be carried out on the lightning stroke transient process of the high-voltage transmission line, and reliable data support is provided for lightning protection design optimization.

Description

Technical Field

[0001] This invention relates to the field of lightning protection and electromagnetic transient analysis technology for high-voltage transmission lines, and in particular to a method and system for lightning transient analysis of high-voltage transmission lines. Background Technology

[0002] In the operation of high-voltage transmission lines, lightning strikes are a major contributing factor to insulation breakdown, power outages, and even large-scale blackouts, seriously threatening the safe and stable operation of the power system. Therefore, accurately analyzing the transient response of transmission lines under lightning excitation is crucial for improving the power system's lightning resistance, optimizing lightning protection device design, and developing reliable operation and maintenance strategies. Currently, research and engineering applications of lightning transient processes in high-voltage transmission lines mainly focus on three aspects: firstly, traditional equivalent circuit models and electromagnetic transient simulation tools. The equivalent circuit method (Lumped-Parameter Model) uses segmented inductors, capacitors, and resistors to represent the transmission line; representative tools include EMTP (Electromagnetic Transients Program) and ATP (Alternative Electromagnetic Transients Program). Methods such as Transients Program (TP) and PSS / E offer advantages such as simplified models, high computational efficiency, and ease of coupling simulations with other parts of the power system. However, they suffer from limitations such as inability to accurately characterize the spatial propagation characteristics of lightning pulses along conductors, insufficient consideration of complex geometries and material property differences in heterogeneous insulators, lightning conductors, and tower structures, and difficulty in simulating the reflection and scattering effects of electromagnetic waves at the air-soil interface. Finite Difference / Finite Element Method (FDTD / FEM), on the other hand, discretizes continuous space through a mesh and solves the electromagnetic wave equations in the time or frequency domain using numerical methods. It has been applied to the study of two-dimensional models of single overhead conductors or simple tower structures. Its advantages include the ability to simulate the propagation, reflection, and scattering of electromagnetic waves and to better reflect the characteristics of distributed parameters. However, two-dimensional or cross-sectional models cannot fully reflect three-dimensional structural scenes, and the computational load increases quadratically or cubically with mesh refinement, resulting in low simulation efficiency and making it unsuitable for large-scale transmission lines. Furthermore, it lacks a unified and efficient numerical framework for multi-physics coupling (such as electrothermal effects and dielectric nonlinearity). Secondly, there is the lightning current excitation model: The International Electrotechnical Commission (IEC62305-1) and IEEE Std. C62.41.2 recommend using typical waveforms such as 8 / 20μs and 10 / 350μs as the standard waveform source for the lightning current model. However, the waveform parameters of such models are fixed, making it difficult to reflect the influence of different thunderstorms, current lock-in, and tower geometry on the current waveform. The distributed parameter source model regards the lightning channel as a distributed parameter transmission line coupled with the atmospheric electric field and tower structure. Currently, it is in the theoretical research stage and lacks mature engineering implementation methods.Thirdly, regarding the current status of lightning protection devices and their operation and maintenance, lightning protection wires and grounding systems are installed at the top of the line to guide the lightning current into the grounding grid. However, the grounding grid design is usually based on empirical coefficients to configure the grounding devices, making it difficult to optimize for the characteristics of lightning pulses. In terms of hardware and insulator selection, the insulator's ability to withstand lightning overvoltage depends on tests and empirical formulas. In areas with strong lightning, the insulation configuration of high-span lines is mostly based on empirical safety margins, lacking a refined design basis. In terms of on-site monitoring and diagnosis, although some lines are equipped with current sensors, overvoltage monitoring devices, and online partial discharge detection, the number of monitoring points is limited, making it difficult to cover the dynamic electromagnetic process of the entire line. Furthermore, post-event diagnosis relies on results such as broken wires and damaged lightning protection wires, lacking real-time analysis capabilities.

[0003] Under the current technological background, the transient analysis techniques for lightning strikes on high-voltage transmission lines mainly rely on equivalent circuit simulation and finite difference / finite element local models. While each has its advantages and disadvantages, several significant shortcomings remain: First, insufficient spatial resolution: Equivalent circuit models cannot reflect the distribution characteristics of lightning current along different conductor segments and tower accessories, making it difficult to accurately locate high-risk areas. Second, inadequate consideration of geometric and material complexity: Complex tower structures, combinations of multiple lightning protection wires and insulation strings, and differences in electromagnetic parameters of various fittings and their heterogeneous materials are often simplified in existing models, leading to biased analysis results. Third, a conflict exists between numerical computation efficiency and large-scale application: Although the FDTD / FEM method has high physical accuracy, the computational load is too large for large-scale full-wave simulation of transmission lines, failing to meet the needs of engineering-level online auxiliary decision-making. Furthermore, a unified multiphysics coupling framework is lacking: Lightning transients involve not only electromagnetic wave propagation but also multiple physical phenomena such as electrothermal effects, nonlinear dielectric breakdown, and tower vibration. Current research mostly focuses on single-scenario analysis, making comprehensive evaluation difficult. Furthermore, lightning current source models lack dynamic coupling and environmental sensitivity: standard waveform sources (such as 8 / 20) 10 / 350 Fixed parameters cannot reflect the dynamic impact of thunderstorm intensity, air channel conductivity, and tower diversion effect on lightning waveforms. While distributed parameter source models can describe channel transmission characteristics, they are not coupled with the three-dimensional structure of the line and the atmospheric electric field, making engineering applications difficult. Finally, online monitoring and real-time early warning capabilities are weak: field monitoring equipment is mostly concentrated at a few nodes in the line, resulting in sparse and incomplete data. Furthermore, the monitoring system is disconnected from numerical simulation, making it impossible to quickly diagnose risks and provide scheduling or maintenance recommendations based on real-time electromagnetic transient responses. Summary of the Invention

[0004] The present invention aims to provide a method and system for transient analysis of lightning strikes on high-voltage transmission lines to solve the above-mentioned technical problems, avoid inaccurate risk positioning due to insufficient accuracy of simplified circuit models, and enable high-precision full-domain simulation of the transient process of lightning strikes on high-voltage transmission lines, providing reliable data support for lightning protection design optimization.

[0005] To address the aforementioned technical problems, this invention provides a method for transient analysis of lightning strikes on high-voltage transmission lines, comprising: Obtain transmission line parameters, material electromagnetic parameters, and atmospheric lightning strike channel parameters; Based on transmission line parameters, material electromagnetic parameters, and preset grid size, an initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells is constructed. Based on the initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells, atmospheric lightning channel parameters, preset waveform, preset disturbance, preset contact area, and preset time step, a three-dimensional electromagnetic field partial differential model corresponding to several grid cells is obtained. For any three-dimensional electromagnetic partial differential model corresponding to a grid cell, the following steps are performed: the three-dimensional electromagnetic partial differential model corresponding to the grid cell is discretized in time and space to obtain the electric field intensity, the current density, and the magnetic field intensity corresponding to the grid cell. Obtain the structural material parameters corresponding to the mesh element; Based on the electric field strength, preset reference conductivity, preset reference temperature, magnetic field strength, current density, structural material parameters, and preset material yield threshold of the grid cell, the simulated voltage data and simulated current data of the grid cell are obtained. The measured data corresponding to the grid cell are obtained, and based on the measured data, simulated voltage data, and simulated current data corresponding to the grid cell, the rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error are calculated. If the rise time error is less than or equal to a preset time threshold, the peak amplitude error is less than or equal to a preset amplitude error threshold, and the high-frequency component amplitude-frequency response error is less than or equal to a preset amplitude-frequency response error threshold, then the three-dimensional electromagnetic field partial differential model corresponding to the grid cell is determined to meet the preset convergence condition, thereby achieving accurate simulation of the transient process of lightning strike on high-voltage transmission lines through the three-dimensional electromagnetic field partial differential model.

[0006] In the above scheme, the acquisition of transmission line parameters, material electromagnetic parameters, and atmospheric lightning strike channel parameters provides the basic input data for constructing a three-dimensional electromagnetic field partial differential model. Next, by building an initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells, the high-voltage transmission line and its surrounding area are discretized, decomposing the complex overall electromagnetic field into multiple computable grid cells. Then, by combining atmospheric lightning strike channel parameters, preset waveforms, preset disturbances, preset contact areas, and preset time steps, the initial three-dimensional electromagnetic field partial differential model is optimized and adjusted to obtain three-dimensional electromagnetic field partial differential models corresponding to several grid cells, making the model more closely reflect the electromagnetic field variation patterns under actual lightning strike scenarios. Then, by performing spatiotemporal discretization on the three-dimensional electromagnetic field partial differential model corresponding to any grid cell, key physical quantities such as electric field strength, current density, and magnetic field strength during the lightning transient process can be obtained, along with structural material parameters, providing structural-level parameter basis for subsequent multiphysics coupling analysis and simulation data calculation. Subsequently, by combining electric field strength, preset reference conductivity, preset reference temperature, magnetic field strength, current density, structural material parameters, and preset material yield threshold, simulated voltage and current data are calculated to reflect the electrical impact of lightning strikes on the line. Furthermore, by acquiring measured data and comparing it with the simulated voltage and current data, rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error are obtained to verify the accuracy of the three-dimensional electromagnetic field partial differential model. If the rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error all meet their corresponding preset thresholds, the three-dimensional electromagnetic field partial differential model is determined to meet the preset convergence conditions. This avoids inaccurate risk positioning due to insufficient accuracy of simplified circuit models, enabling high-precision full-domain simulation of the transient process of lightning strikes on high-voltage transmission lines, and providing reliable data support for lightning protection design optimization.

[0007] Furthermore, it also includes: If the rise time error is greater than the preset time threshold, or the peak amplitude error is greater than the preset amplitude error threshold, or the high-frequency component amplitude-frequency response error is greater than the preset amplitude-frequency response error threshold, then the preset mesh size, material electromagnetic parameters, or preset time step are adjusted, and the rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error are recalculated until the preset convergence condition is met, and the three-dimensional electromagnetic field partial differential model corresponding to the mesh element is obtained.

[0008] In the above scheme, if any of the errors—rise time error, peak amplitude error, or high-frequency component amplitude-frequency response error—exceeds the standard, the three-dimensional electromagnetic field partial differential model (PED model) is determined to require optimization. Next, after determining that the PDD model needs optimization, the input parameters of the PDD model are optimized by specifically adjusting the preset mesh size, material electromagnetic parameters, or preset time step, thereby improving simulation accuracy. Then, using the adjusted preset mesh size, material electromagnetic parameters, or preset time step, the rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error are recalculated to verify the improvement effect on the accuracy of the PDD model. Finally, by repeatedly executing the parameter adjustment and error recalculation process, the rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error all meet their corresponding preset thresholds, thus obtaining a three-dimensional electromagnetic field PDD model that meets the preset convergence conditions.

[0009] Furthermore, based on transmission line parameters, material electromagnetic parameters, and a preset grid size, an initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells is constructed. Based on this initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells, atmospheric lightning channel parameters, preset waveforms, preset disturbances, preset contact areas, and preset time steps, a three-dimensional electromagnetic field partial differential model corresponding to several grid cells is obtained; including: Based on transmission line parameters, material electromagnetic parameters, and preset mesh size, an initial three-dimensional electromagnetic field partial differential model corresponding to several mesh elements is constructed. Obtain atmospheric lightning strike channel parameters; Based on atmospheric lightning channel parameters, a lightning channel transmission line model is constructed; An initial lightning strike current is generated based on a preset waveform and a preset disturbance. Based on the preset contact area and initial lightning current, a current density source term is constructed; Based on a preset time step, the initial three-dimensional electromagnetic field partial differential model and the lightning strike channel transmission line model are synchronized in time. Based on the time-synchronized initial three-dimensional electromagnetic field partial differential model and the current density source term, the three-dimensional electromagnetic field partial differential models corresponding to several grid cells are obtained.

[0010] In the above scheme, an initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells is constructed by combining transmission line parameters, material electromagnetic parameters, and preset grid sizes. This allows for the discretization and modeling of the high-voltage transmission line and its surrounding space, decomposing the complex three-dimensional electromagnetic field into multiple grid cells, thus laying the foundation model framework for the subsequent introduction of lightning-related conditions. Next, a lightning channel transmission line model is established using atmospheric lightning channel parameters, simplifying the atmospheric lightning channel and enabling a mathematical description of the lightning current propagation process. Then, an initial lightning current consistent with the actual lightning strike scenario is generated using preset waveforms and preset perturbations, providing a near-realistic excitation source. Subsequently, a current density source term is constructed based on a preset contact area and the initial lightning current, thereby transforming the initial lightning current into a source term that can be injected into the three-dimensional electromagnetic field model. Finally, by synchronizing the initial three-dimensional electromagnetic field partial differential model and the lightning strike channel transmission line model with a preset time step, the computational consistency of the two models in the time dimension can be guaranteed. At the same time, the current density source term is integrated into the time-synchronized initial three-dimensional electromagnetic field partial differential model, and finally, a three-dimensional electromagnetic field partial differential model corresponding to several grid cells is obtained, so that the model can fully reflect the dynamic changes of the electromagnetic field during the lightning strike transient process.

[0011] Furthermore, the construction of an initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells based on transmission line parameters, material electromagnetic parameters, and a preset grid size includes: Construct the initial computational domain; Based on the transmission line parameters and the initial computational domain, a three-dimensional computational domain is obtained; Based on the preset mesh size, the three-dimensional computational domain is meshed to obtain several mesh elements; The material's electromagnetic parameters are mapped to the corresponding mesh elements, and an initial three-dimensional electromagnetic field partial differential model corresponding to several mesh elements is constructed based on the preset Maxwell's time-domain equations and the material's electromagnetic parameters.

[0012] In the above scheme, an initial computational domain is first constructed, and then geometrically corrected and refined based on the transmission line parameters to obtain a three-dimensional computational domain that accurately reflects the spatial structure of the transmission line. This provides a precise spatial carrier for the subsequent initial three-dimensional electromagnetic field partial differential model. Next, the three-dimensional computational domain is divided according to a preset mesh size, generating several mesh elements. This numerical decomposition of the three-dimensional computational domain lays the foundation for subsequent parameter mapping and equation solving. Then, the material electromagnetic parameters are mapped and assigned to the corresponding mesh elements, enabling the construction of the initial three-dimensional electromagnetic field partial differential model for each mesh element based on the preset Maxwell's time-domain equations.

[0013] Further, for each three-dimensional electromagnetic field partial differential model corresponding to a grid cell, the following steps are performed: the three-dimensional electromagnetic field partial differential model corresponding to the grid cell is spatiotemporally discretized to obtain the electric field intensity, current density, and magnetic field intensity corresponding to the grid cell; including: The three-dimensional electromagnetic field partial differential model corresponding to the mesh element is spatially discretized to construct the stiffness matrix, mass matrix, and excitation vector corresponding to the mesh element. Based on the stiffness matrix, the mass matrix, the excitation vector, and the three-dimensional electromagnetic partial differential model corresponding to the mesh element, the system of ordinary differential equations corresponding to the mesh element is obtained. Discretize and solve the system of ordinary differential equations in time to obtain the discrete linear model corresponding to the grid cell; Based on the discrete linear model and the preset solver, the time coefficient corresponding to the grid cell is obtained; Based on the time coefficient, the electric field strength, current density, and magnetic field strength corresponding to the grid cell are obtained.

[0014] In the above scheme, by spatially discretizing the three-dimensional electromagnetic field partial differential model corresponding to the grid cell, a stiffness matrix reflecting the correlation of the electromagnetic properties of the grid cell, a mass matrix reflecting the dielectric properties of the material, and an excitation vector carrying the lightning current excitation can be constructed, providing a discretized mathematical foundation for subsequent equation solving. Next, by substituting the constructed stiffness matrix, mass matrix, and excitation vector into the three-dimensional electromagnetic field partial differential model, the complex partial differential equations can be transformed into a system of ordinary differential equations that are easier to calculate numerically, realizing the transformation of the model from partial differential form to ordinary differential form. Then, by discretizing the system of ordinary differential equations in time, the continuous changes in the time dimension can be transformed into numerical iterations at discrete time nodes, thus obtaining a discrete linear model, completing the discretization of the spatiotemporal dimensions. Furthermore, by calling a preset solver to solve the discrete linear model, time coefficients are obtained, providing key coefficient support for calculating the electric field strength. Finally, by further calculating the time coefficients obtained from the solution, the electric field strength, current density, and magnetic field strength of each grid cell and each time step can be obtained, yielding the core electromagnetic physical quantities in the lightning transient process.

[0015] Further, the step of obtaining the simulated voltage data and simulated current data corresponding to the grid cell based on the electric field strength, preset reference conductivity, preset reference temperature, magnetic field strength, current density, structural material parameters, and preset material yield threshold of the grid cell includes: Based on the electric field strength, preset reference conductivity, preset reference temperature, magnetic field strength, current density, and structural material parameters corresponding to the grid cell, the stress field corresponding to the grid cell is solved. Based on the stress field and the preset material yield threshold, the fatigue damage factor corresponding to the grid cell is calculated, and the device lifetime within the corresponding grid cell is predicted based on the fatigue damage factor. Based on the device lifetime and the preset standard device lifetime, the corresponding lifetime difference is obtained. If the lifetime difference is greater than or equal to the preset lifetime threshold, the preset grid size or material electromagnetic parameters are adjusted, and the device lifetime in the corresponding grid cell is re-predicted until the lifetime difference is less than the preset lifetime threshold. Then, based on the electric field strength, current density, and magnetic field strength of the grid cell, the simulated voltage data and simulated current data of the grid cell are obtained.

[0016] In the above scheme, the stress field of each grid cell is obtained by combining electric field strength, preset reference conductivity, preset reference temperature, magnetic field strength, current density, and structural material parameters, providing a mechanical analysis basis for subsequent life assessment. Next, by using the obtained stress field and preset material yield threshold, the fatigue damage factor is calculated, which quantifies the cumulative damage of lightning transient stress to the device and predicts the device life within the corresponding grid cell, realizing the transformation from mechanical analysis to life assessment. Finally, by calculating the life difference between the device life and the preset standard device life, if the life difference is greater than or equal to the preset life threshold, it indicates that there is room for optimization in the current grid size or material electromagnetic parameters. The preset grid size or material electromagnetic parameters are adjusted, and the device life is re-predicted using the adjusted preset grid size and material electromagnetic parameters until the life difference is less than the preset life threshold. That is, under the premise that the device life meets the requirements, simulated voltage and current data with both electrical accuracy and life safety are obtained based on electric field strength and current density.

[0017] Further, the step of solving the stress field corresponding to the grid cell based on the electric field strength, preset reference conductivity, preset reference temperature, magnetic field strength, current density, and structural material parameters corresponding to the grid cell includes: The Joule heat source is calculated based on the electric field intensity corresponding to the grid cell, and the three-dimensional heat conduction equation is solved based on the Joule heat source to obtain the temperature field corresponding to the grid cell. Based on the temperature field, the preset reference conductivity, and the preset reference temperature, calculate the conductivity corresponding to the grid cell. Based on the conductivity, the magnetic field strength corresponding to the grid cell, and the current density corresponding to the grid cell, the electromagnetic force distribution corresponding to the grid cell is solved. Based on the electromagnetic force distribution and the structural material parameters corresponding to the grid cell, a three-dimensional elasticity equation is established, and the stress field corresponding to the grid cell is solved based on the three-dimensional elasticity equation.

[0018] In the above scheme, the Joule heat source of each grid cell is obtained by calculating the electric field strength. Then, the Joule heat source is substituted into the three-dimensional heat conduction equation to solve for the temperature field, providing temperature data support for subsequent conductivity calculations. Next, the temperature-corrected conductivity is calculated using the temperature field, a preset reference conductivity, and a preset reference temperature, ensuring dynamic matching between the material's electromagnetic properties and the temperature field in subsequent electromagnetic force calculations. Then, the electromagnetic force distribution of each grid cell is obtained by solving for conductivity, magnetic field strength, and current density, clarifying the magnitude and spatial distribution of the electromagnetic load on the structure under lightning transients. Finally, a three-dimensional elasticity equation is established using the obtained electromagnetic force distribution and structural material parameters. Solving this equation yields the stress field of each grid cell, completing the analytical transformation from electromagnetic load to mechanical stress.

[0019] This invention provides a transient analysis system for lightning strikes on high-voltage transmission lines, comprising a parameter acquisition module, a model building module, a spatiotemporal discretization module, a structural material parameter acquisition module, a lightning strike transient simulation module, and a model verification module, specifically: The parameter acquisition module is used to acquire transmission line parameters, material electromagnetic parameters, and atmospheric lightning strike channel parameters; The model building module is used to construct an initial three-dimensional electromagnetic field partial differential model corresponding to several grid units based on transmission line parameters, material electromagnetic parameters and preset grid size, and to obtain a three-dimensional electromagnetic field partial differential model corresponding to several grid units based on the initial three-dimensional electromagnetic field partial differential model corresponding to several grid units, atmospheric lightning channel parameters, preset waveform, preset disturbance, preset contact area and preset time step. The spatiotemporal discretization module is used to perform the following steps on the three-dimensional electromagnetic field partial differential model corresponding to any grid cell: spatiotemporally discretize the three-dimensional electromagnetic field partial differential model corresponding to the grid cell to obtain the electric field intensity, the current density and the magnetic field intensity corresponding to the grid cell. The structural material parameter acquisition module is used to acquire the structural material parameters corresponding to the grid unit; The lightning transient simulation module is used to obtain the simulation voltage data and simulation current data of the grid cell based on the electric field strength, preset reference conductivity, preset reference temperature, magnetic field strength, current density, structural material parameters and preset material yield threshold of the grid cell. The model verification module is used to acquire the measured data corresponding to the grid cell, and calculate the rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error based on the measured data, simulated voltage data, and simulated current data corresponding to the grid cell. If the rise time error is less than or equal to a preset time threshold, the peak amplitude error is less than or equal to a preset amplitude error threshold, and the high-frequency component amplitude-frequency response error is less than or equal to a preset amplitude-frequency response error threshold, then the three-dimensional electromagnetic field partial differential model corresponding to the grid cell is determined to meet the preset convergence condition, thereby achieving accurate simulation of the transient process of lightning strike on high-voltage transmission lines through the three-dimensional electromagnetic field partial differential model.

[0020] This invention provides a transient analysis system for lightning strikes on high-voltage transmission lines. In practical applications, only a parameter acquisition module is needed to obtain transmission line parameters, material electromagnetic parameters, and atmospheric lightning channel parameters, providing basic input data for constructing a three-dimensional electromagnetic field partial differential model. Then, a model construction module is used to build an initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells. The high-voltage transmission line and its surrounding area are discretized, decomposing the complex overall electromagnetic field into multiple computable grid cells. The initial three-dimensional electromagnetic field partial differential model is then optimized and adjusted by combining atmospheric lightning channel parameters, preset waveforms, preset disturbances, preset contact areas, and preset time steps to obtain three-dimensional electromagnetic field partial differential models corresponding to several grid cells, making the model more closely reflect the electromagnetic field variation patterns under actual lightning strike scenarios. Then, a spatiotemporal discretization module is used to perform spatiotemporal discretization on the three-dimensional electromagnetic field partial differential model corresponding to any grid cell. This allows for the acquisition of key physical quantities such as electric field strength, current density, and magnetic field strength during the lightning strike transient process. A structural material parameter acquisition module is then used to obtain structural material parameters, providing structural-level parameter basis for subsequent multiphysics coupling analysis and simulation data calculation. Subsequently, a lightning strike transient simulation module is employed, combining electric field strength, preset reference conductivity, preset reference temperature, magnetic field strength, current density, structural material parameters, and preset material yield threshold to comprehensively calculate simulated voltage and current data, thereby reflecting the electrical impact of lightning strikes on the line. Finally, a model verification module is used to obtain measured data and compare it with simulated voltage and current data to obtain rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error. These errors are used to verify the accuracy of the three-dimensional electromagnetic field partial differential model. If the rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error all meet the corresponding preset thresholds, then the three-dimensional electromagnetic field partial differential model is determined to meet the preset convergence conditions. This can avoid inaccurate risk positioning due to insufficient accuracy of simplified circuit models, and achieve high-precision full-domain simulation of the transient process of lightning strikes on high-voltage transmission lines, providing reliable data support for lightning protection design optimization.

[0021] Furthermore, the model verification module is also used for: If the rise time error is greater than the preset time threshold, or the peak amplitude error is greater than the preset amplitude error threshold, or the high-frequency component amplitude-frequency response error is greater than the preset amplitude-frequency response error threshold, then the preset mesh size, material electromagnetic parameters, or preset time step are adjusted, and the rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error are recalculated until the preset convergence condition is met, and the three-dimensional electromagnetic field partial differential model corresponding to the mesh element is obtained.

[0022] In the above scheme, if any of the errors—rise time error, peak amplitude error, or high-frequency component amplitude-frequency response error—exceeds the standard, the three-dimensional electromagnetic field partial differential model (PED model) is determined to require optimization. Next, after determining that the PDD model needs optimization, the input parameters of the PDD model are optimized by specifically adjusting the preset mesh size, material electromagnetic parameters, or preset time step, thereby improving simulation accuracy. Then, using the adjusted preset mesh size, material electromagnetic parameters, or preset time step, the rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error are recalculated to verify the improvement effect on the accuracy of the PDD model. Finally, by repeatedly executing the parameter adjustment and error recalculation process, the rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error all meet their corresponding preset thresholds, thus obtaining a three-dimensional electromagnetic field PDD model that meets the preset convergence conditions.

[0023] Furthermore, the model building module is used to construct an initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells based on transmission line parameters, material electromagnetic parameters, and a preset grid size, and to obtain a three-dimensional electromagnetic field partial differential model corresponding to several grid cells based on the initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells, atmospheric lightning channel parameters, preset waveform, preset disturbance, preset contact area, and preset time step; including: Based on transmission line parameters, material electromagnetic parameters, and preset mesh size, an initial three-dimensional electromagnetic field partial differential model corresponding to several mesh elements is constructed. Obtain atmospheric lightning strike channel parameters; Based on atmospheric lightning channel parameters, a lightning channel transmission line model is constructed; An initial lightning strike current is generated based on a preset waveform and a preset disturbance. Based on the preset contact area and initial lightning current, a current density source term is constructed; Based on a preset time step, the initial three-dimensional electromagnetic field partial differential model and the lightning strike channel transmission line model are synchronized in time. Based on the time-synchronized initial three-dimensional electromagnetic field partial differential model and the current density source term, the three-dimensional electromagnetic field partial differential models corresponding to several grid cells are obtained.

[0024] In the above scheme, an initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells is constructed by combining transmission line parameters, material electromagnetic parameters, and preset grid sizes. This allows for the discretization and modeling of the high-voltage transmission line and its surrounding space, decomposing the complex three-dimensional electromagnetic field into multiple grid cells, thus laying the foundation model framework for the subsequent introduction of lightning-related conditions. Next, a lightning channel transmission line model is established using atmospheric lightning channel parameters, simplifying the atmospheric lightning channel and enabling a mathematical description of the lightning current propagation process. Then, an initial lightning current consistent with the actual lightning strike scenario is generated using preset waveforms and preset perturbations, providing a near-realistic excitation source. Subsequently, a current density source term is constructed based on a preset contact area and the initial lightning current, thereby transforming the initial lightning current into a source term that can be injected into the three-dimensional electromagnetic field model. Finally, by synchronizing the initial three-dimensional electromagnetic field partial differential model and the lightning strike channel transmission line model with a preset time step, the computational consistency of the two models in the time dimension can be guaranteed. At the same time, the current density source term is integrated into the time-synchronized initial three-dimensional electromagnetic field partial differential model, and finally, a three-dimensional electromagnetic field partial differential model corresponding to several grid cells is obtained, so that the model can fully reflect the dynamic changes of the electromagnetic field during the lightning strike transient process. Attached Figure Description

[0025] Figure 1 A flowchart of a transient analysis method for lightning strikes on high-voltage transmission lines provided in an embodiment of the present invention; Figure 2 This is an architecture diagram of a transient analysis system for lightning strikes on high-voltage transmission lines, provided as an embodiment of the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] This embodiment provides a method for transient analysis of lightning strikes on high-voltage transmission lines. Please refer to the flowchart below. Figure 1 ,include: Step S1: Obtain transmission line parameters, material electromagnetic parameters, and atmospheric lightning strike channel parameters; Step S2: Based on the transmission line parameters, material electromagnetic parameters and preset grid size, construct an initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells, and based on the initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells, atmospheric lightning channel parameters, preset waveform, preset disturbance, preset contact area and preset time step, obtain the three-dimensional electromagnetic field partial differential model corresponding to several grid cells. Step S3: Perform the following steps on the three-dimensional electromagnetic field partial differential model corresponding to any grid cell: perform spatiotemporal discretization on the three-dimensional electromagnetic field partial differential model corresponding to the grid cell, and obtain the electric field intensity, current density and magnetic field intensity corresponding to the grid cell. Step S4: Obtain the structural material parameters corresponding to the mesh element; Step S5: Based on the electric field strength, preset reference conductivity, preset reference temperature, magnetic field strength, current density, structural material parameters, and preset material yield threshold of the grid cell, obtain the simulated voltage data and simulated current data of the grid cell. Step S6: Obtain the measured data corresponding to the grid cell, and calculate the rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error based on the measured data, simulated voltage data, and simulated current data corresponding to the grid cell. If the rise time error is less than or equal to a preset time threshold, the peak amplitude error is less than or equal to a preset amplitude error threshold, and the high-frequency component amplitude-frequency response error is less than or equal to a preset amplitude-frequency response error threshold, then the three-dimensional electromagnetic field partial differential model corresponding to the grid cell meets the preset convergence condition, thereby achieving accurate simulation of the transient process of lightning strike on high-voltage transmission lines through the three-dimensional electromagnetic field partial differential model.

[0028] In this embodiment, CAD modeling or high-precision 3D laser scanning is used to obtain the geometric surfaces and volume elements of the tower and its accessories. Simultaneously, the conductor cross-section is interpolated to generate a spatial curve based on the actual diameter, span, and sag shape. Furthermore, insulator strings and fittings are modeled according to their actual dimensions and arrangement to obtain transmission line parameters. By acquiring transmission line parameters, material electromagnetic parameters, and atmospheric lightning strike channel parameters, basic input data is provided for constructing a 3D electromagnetic field partial differential model. Next, by building an initial 3D electromagnetic field partial differential model corresponding to several grid cells, the high-voltage transmission line and its surrounding area are discretized, decomposing the complex overall electromagnetic field into multiple computable grid cells. Then, by combining atmospheric lightning strike channel parameters, preset waveforms, preset disturbances, preset contact areas, and preset time steps, the initial 3D electromagnetic field partial differential model is optimized and adjusted to obtain 3D electromagnetic field partial differential models corresponding to several grid cells, making the model more closely reflect the electromagnetic field variation patterns under actual lightning strike scenarios. Then, by performing spatiotemporal discretization on the three-dimensional electromagnetic field partial differential model corresponding to any grid cell, key physical quantities such as electric field strength, current density, and magnetic field strength during the lightning transient process can be obtained, along with structural material parameters. This provides structural-level parameter basis for subsequent multiphysics coupling analysis and simulation data calculation. Subsequently, combining the electric field strength, preset reference conductivity, preset reference temperature, magnetic field strength, current density, structural material parameters, and preset material yield threshold, the experimentally measured waveform is imported into the three-dimensional electromagnetic field partial differential model of this embodiment, and simulation under the same conditions is performed to obtain simulated voltage data. and simulated current data This reflects the electrical impact of lightning strikes on power lines. Furthermore, experimental data was obtained in the laboratory; specifically, the test setup used a pulse generator conforming to IEC / IEEE standards, capable of outputting 8 / 20... With 10 / 350 Two typical lightning strike waveforms are tested, with a maximum current amplitude of up to 200 kA. The test sample is a scaled-down model consisting of a conductor segment, insulator string, and fittings, manufactured at a scale of 1:10 or 1:20 while maintaining electrical equivalence. High-speed current transformers (bandwidth ≥ 10 MHz) and voltage probes are installed at both ends of the conductor and key nodes of the insulator string, respectively. Test procedure: Set the waveform and amplitude, and apply the voltage to the input terminal of the test piece through a step-up transformer; synchronously trigger data acquisition and record the measured current data. Compared with measured voltage data By comparing the measured current data with the simulated current data, and the measured voltage data with the simulated voltage data, through... The rise time error is obtained (where, Indicates rise time error. This indicates the rise time of the measured lightning current. (representing the simulated rise time of the lightning current), through The peak amplitude error is obtained (where, Indicates the peak amplitude error. This represents the maximum peak current measured by lightning. The maximum peak current obtained through numerical simulation and the high-frequency component amplitude-frequency response error obtained through FFT analysis of the waveform are used to verify the accuracy of the three-dimensional electromagnetic field partial differential model. If the rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error all meet the corresponding preset thresholds, specifically: rise time error Peak amplitude error And the amplitude-frequency response error of the high-frequency components does not exceed This confirms that the three-dimensional electromagnetic field partial differential model meets the preset convergence conditions, avoiding inaccurate risk positioning due to insufficient accuracy of simplified circuit models. It enables high-precision, full-domain simulation of the transient lightning strike process on high-voltage transmission lines, providing reliable data support for lightning protection design optimization. This embodiment achieves full-space, full-time dynamic visualization of the electric field, magnetic field, and current distribution under lightning transients, overcoming the shortcomings of traditional lumped parameter or quasi-static models that cannot accurately describe spatial distribution effects and the influence of non-uniform medium boundaries.

[0029] This embodiment can also obtain measured data through on-site comparative tests. Specifically, the test line is selected as a high-span transmission line section (length ≥ 10 km) with historical lightning strike records, and monitoring devices for intermediate guy wires and lightning protection wires are installed along the line; high-speed sensors are installed at the top and end of 3–5 towers to record the current / voltage waveforms of natural lightning strike events. A multi-channel data recording system with a high sampling rate is used to capture the details of lightning strike transients. The acquired raw waveforms are transmitted in real-time to a simulator via fiber optic or wireless links for simulation. For each natural lightning strike event, the initial waveform of the lightning channel is extracted. ,in Indicates the wavefront rise time constant; This represents the time characteristic of reaching the peak value; Indicates the maximum current amplitude; This represents random disturbances or correction terms, reflecting the uncertainty of the lightning waveform. In the three-dimensional electromagnetic field partial differential model of this embodiment, the same initial excitation is used for simulation, outputting the electric field and current distribution of key towers, and comparing it with measured data to obtain spatial distribution error (the difference between the simulated overvoltage peak value and the measured value between different towers, similar to the above peak amplitude error calculation process), time series error (similar to the rise time error calculation process in the laboratory, used to evaluate the matching degree of time and amplitude), and reliability index (the simulation hit rate (the proportion of errors within a predetermined threshold) in multiple natural lightning strike events). If the spatial distribution error, time series error, and reliability index all meet the corresponding preset thresholds, specifically: spatial distribution error... Time series error And reliability indicators This confirms that the three-dimensional electromagnetic field partial differential model meets the preset convergence conditions.

[0030] Furthermore, it also includes: If the rise time error is greater than the preset time threshold, or the peak amplitude error is greater than the preset amplitude error threshold, or the high-frequency component amplitude-frequency response error is greater than the preset amplitude-frequency response error threshold, then the preset mesh size, material electromagnetic parameters, or preset time step are adjusted, and the rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error are recalculated until the preset convergence condition is met, and the three-dimensional electromagnetic field partial differential model corresponding to the mesh element is obtained.

[0031] In this embodiment, if any of the rise time error, peak amplitude error, or high-frequency component amplitude-frequency response error exceeds the standard, the three-dimensional electromagnetic field partial differential model is determined to require optimization. Next, after determining that the three-dimensional electromagnetic field partial differential model needs optimization, the input parameters of the three-dimensional electromagnetic field partial differential model are optimized by specifically adjusting the preset mesh size, material electromagnetic parameters, or preset time step, thereby improving simulation accuracy. Then, using the adjusted preset mesh size, material electromagnetic parameters, or preset time step, the rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error are recalculated to verify the improvement effect on the accuracy of the three-dimensional electromagnetic field partial differential model. Finally, by repeatedly executing the parameter adjustment and error recalculation process until the rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error all meet the corresponding preset thresholds, a three-dimensional electromagnetic field partial differential model that meets the preset convergence conditions is obtained.

[0032] Furthermore, based on transmission line parameters, material electromagnetic parameters, and a preset grid size, an initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells is constructed. Based on this initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells, atmospheric lightning channel parameters, preset waveforms, preset disturbances, preset contact areas, and preset time steps, a three-dimensional electromagnetic field partial differential model corresponding to several grid cells is obtained; including: Based on transmission line parameters, material electromagnetic parameters, and preset mesh size, an initial three-dimensional electromagnetic field partial differential model corresponding to several mesh elements is constructed. Obtain atmospheric lightning strike channel parameters; Based on atmospheric lightning channel parameters, a lightning channel transmission line model is constructed; An initial lightning strike current is generated based on a preset waveform and a preset disturbance. Based on the preset contact area and initial lightning current, a current density source term is constructed; Based on a preset time step, the initial three-dimensional electromagnetic field partial differential model and the lightning strike channel transmission line model are synchronized in time. Based on the time-synchronized initial three-dimensional electromagnetic field partial differential model and the current density source term, the three-dimensional electromagnetic field partial differential models corresponding to several grid cells are obtained.

[0033] In this embodiment, an initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells is constructed by combining transmission line parameters, material electromagnetic parameters, and preset grid sizes. This allows for the discretization and modeling of the high-voltage transmission line and its surrounding space, decomposing the complex three-dimensional electromagnetic field into multiple grid cells, thus laying the foundation model framework for the subsequent introduction of lightning-related conditions. Next, a lightning channel transmission line model is established using atmospheric lightning channel parameters. in For the distributed inductance of the air channel, For the distributed capacitance of the air channel, For the distributed resistance of the air channel, The distributed conductivity of the air channel is a parameter of the atmospheric lightning strike channel; Let be the current intensity at time t and channel height (coordinate z); Let be the voltage at time t and channel height (coordinate z); thus simplifying the atmospheric lightning channel into a one-dimensional transmission line that satisfies the Telegrapher equation, enabling a mathematical description of the lightning current propagation process. Then, through the top of the cloud... Apply lightning strike voltage or a preset waveform (IEC typical waveform (8 / 20µs, 10 / 350µs) or measured waveform) and a preset disturbance (Gaussian white noise). Or random disturbances measured in the field, such as ,in The disturbance intensity coefficient is... This is the initial lightning strike current. To add Gaussian white noise The lightning current after the strike is obtained by integrating the PDE downwards with depth z. —The lightning current waveform reaching the contact point of the lightning protection wire is generated to produce an initial lightning current that matches the actual lightning strike scenario. This is used to simulate waveform uncertainties in a thunderstorm environment and provide a realistic excitation source. Subsequently, based on the preset contact area and the initial lightning current, a current density source term is constructed. Specifically, the generated initial lightning current is... The current at the location constructs the current density source term: ,in The Dirac distribution is shown along the contact area (preset contact area) of the lightning protection wire, where t is the tangential vector of the conductor. To predetermine the contact area (or the total curve length), the initial lightning current is transformed into a source term that can be injected into a three-dimensional electromagnetic field model. This ensures the conservation of current incidence and total flow rate along the path within the domain. Finally, the initial three-dimensional electromagnetic field partial differential model and the lightning channel transmission line model were synchronized by setting a preset time step: the time step of the lightning channel transmission line model was calculated respectively. With respect to the time step of the partial differential model of electromagnetic field Each of them satisfies the CFL condition, and then the smallest one is taken as the global step size: If the one-dimensional waveform (lightning transmission line model) changes drastically, the amount of [something] can be temporarily reduced. To ensure spatiotemporal synchronization. The synchronization strategy between the lightning strike channel transmission line model and the three-dimensional electromagnetic field partial differential model: at the same global instant... Iterate; at each time step, first calculate on a one-dimensional channel. Then, it is injected into the three-dimensional electromagnetic field partial differential model for electric field update, thereby ensuring the consistency of the calculation of the two models in the time dimension; at the same time, the current density source term is integrated into the initial three-dimensional electromagnetic field partial differential model after time synchronization, and finally the three-dimensional electromagnetic field partial differential model corresponding to several grid cells is obtained, so that the model can fully reflect the dynamic changes of the electromagnetic field during the transient process of lightning strike.

[0034] Furthermore, the construction of an initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells based on transmission line parameters, material electromagnetic parameters, and a preset grid size includes: Construct the initial computational domain; Based on the transmission line parameters and the initial computational domain, a three-dimensional computational domain is obtained; Based on the preset mesh size, the three-dimensional computational domain is meshed to obtain several mesh elements; The material's electromagnetic parameters are mapped to the corresponding mesh elements, and an initial three-dimensional electromagnetic field partial differential model corresponding to several mesh elements is constructed based on the preset Maxwell's time-domain equations and the material's electromagnetic parameters.

[0035] In this embodiment, an initial computational domain is first constructed, and then geometrically corrected and refined based on the transmission line parameters to finally obtain a three-dimensional computational domain that truly reflects the spatial structure of the transmission line. This is a closed system comprising overhead conductors, tower structures, insulator strings, lightning protection wires, and the surrounding medium (air and soil), providing a precise spatial carrier for the subsequent initial three-dimensional electromagnetic field partial differential model. Next, the three-dimensional computational domain is divided according to a preset mesh size, generating several mesh elements (the mesh elements are size-adaptive tetrahedral elements, with the coarseness adaptively refined based on geometric complexity and the expected electric field gradient; and in high field gradient regions such as conductor-air and fitting-air, the mesh size h must satisfy: ,in To be at the highest frequency The wavelength corresponding to the rapid rise time of the lightning pulse (taken as the equivalent frequency) is used to numerically decompose the three-dimensional computational domain, laying the foundation for subsequent parameter mapping and equation solving. Then, the material electromagnetic parameters are mapped and assigned to the corresponding mesh elements, enabling the construction of initial three-dimensional electromagnetic field partial differential models for each mesh element based on the pre-defined Maxwell time-domain equations. In the formula, r represents the position vector in three-dimensional space, generally written as t represents time. It represents the electric field intensity vector, which describes the strength and direction of the electric field at a certain point in three-dimensional space at a certain moment; This indicates the distribution of magnetic permeability in metallic, air, or soil regions. ; It represents the magnetic field strength vector, which describes the strength and direction of the magnetic field at a certain point in three-dimensional space at a certain moment; Represents the conductivity distribution of metals. High, air , soil Changes with depth; This represents the distribution of dielectric constant, which is related to the spatial location r. Different materials Take measured or literature values; The lightning current density source term represents the current density distribution injected into the electromagnetic field during a lightning strike, providing the excitation source for changes in the electromagnetic field. The constitutive relationship between the material's electromagnetic parameters is as follows: In the formula, D represents the electric displacement vector, and B represents the magnetic induction intensity. Boundary and interface conditions must satisfy the following: 1. Conductor-dielectric interface (PEC condition): For the surface of a metallic conductor, the following conditions must be met. Where n is the outward normal vector; 2. Open-domain radiative boundary (absorbing boundary): Apply a first-order absorbing boundary condition (Silver–Müller condition) to the outer cladding of the computational domain: 3. Medium-medium continuity condition: At the interface between different materials, ensure the continuity of the tangential field and the normal displacement. .

[0036] Further, for each three-dimensional electromagnetic field partial differential model corresponding to a grid cell, the following steps are performed: the three-dimensional electromagnetic field partial differential model corresponding to the grid cell is spatiotemporally discretized to obtain the electric field intensity, current density, and magnetic field intensity corresponding to the grid cell; including: The three-dimensional electromagnetic field partial differential model corresponding to the mesh element is spatially discretized to construct the stiffness matrix, mass matrix, and excitation vector corresponding to the mesh element. Based on the stiffness matrix, the mass matrix, the excitation vector, and the three-dimensional electromagnetic partial differential model corresponding to the mesh element, the system of ordinary differential equations corresponding to the mesh element is obtained. Discretize and solve the system of ordinary differential equations in time to obtain the discrete linear model corresponding to the grid cell; Based on the discrete linear model and the preset solver, the time coefficient corresponding to the grid cell is obtained; Based on the time coefficient, the electric field strength, current density, and magnetic field strength corresponding to the grid cell are obtained.

[0037] In this embodiment, the three-dimensional electromagnetic field partial differential model corresponding to the grid cell is spatially discretized. Specifically, the Galerkin finite element method is used for spatial discretization. First, starting from the form of the electric field intensity, the Maxwell time-domain equations are... Both ends and the preset trial function Perform inner product and in the three-dimensional computational domain Integrating, we get: Next, we select Nédélec's first-type edge element (Whitney edge element). To ensure the continuity of the tangential electric field in each element, the electric field and trial function are then expanded: , ,in Represents the finite element basis functions (spatial interpolation functions); The time coefficients of the basis functions (degrees of freedom to be solved) represent the time coefficients; N represents the number of discretized degrees of freedom. The test function (the weighting function in the weak form) is used to construct the stiffness matrix that reflects the correlation of the electromagnetic properties of the mesh elements. Mass matrix reflecting the dielectric properties of materials and the excitation vector carrying the lightning strike current. This provides a discretized mathematical foundation for solving the subsequent equations. Next, by substituting the constructed stiffness matrix, mass matrix, and excitation vector into the three-dimensional electromagnetic field partial differential model, the complex partial differential equations can be transformed into a system of ordinary differential equations that are easier to calculate numerically. This transforms the model from partial differential form to ordinary differential form. Then, the ordinary differential equation system is discretized over time, using either the Crank–Nicolson method or the second-order backward difference (BDF2). Specifically: 1. Using the Crank–Nicolson method: Discretize the time nodes... and ,Pick Discretized as: The linear system is obtained by rearranging: 2. Using second-order backward difference (BDF2): Discretizing the three time steps can improve stability under strong damping conditions. Adaptive step size control is employed in time discretization: based on the local minimum mesh size. From the propagation speed of electromagnetic waves c, we can obtain The CFL is typically set to 0.3–0.5, and through adaptive step size control, it can reduce the impact during periods of rapid change in the lightning surge wave. After stabilizing, the value recovers to a larger value to balance accuracy and efficiency. Through this time discretization, continuous changes in the time dimension can be transformed into numerical iterations at discrete time points, thus obtaining a discrete linear model. (in Depending on the chosen time-domain format, the spatiotemporal dual-dimensional discretization is completed. Further, by calling a preset solver (for symmetric positive definite systems (such as the Crank–Nicolson method), conjugate gradients (CG) can be used; for asymmetric or weakly asymmetric systems, the generalized minimum residual method (GMRES) or the stable biconjugate gradient method (BiCGStab) is selected) to solve the discrete linear model, specifically: 1. First, preprocessing optimization is performed, which can employ multi-level incomplete ILU (with a fill factor p) or algebraic multigrid (AMG): Multi-level incomplete ILU can maximize the reduction of iteration residuals while ensuring acceptable storage overhead; algebraic multigrid (AMG) can construct coarse-fine grids algebraically, using coarse layers to quickly reduce low-frequency errors and fine layers to precisely solve high-frequency errors. Under the effect of preprocessing, the number of iterations for the three-dimensional electromagnetic field partial differential model is typically reduced to 10%–20% of the original. 2. Secondly, all grid cells can be parallelized to realize the spatiotemporal discretization process, and the corresponding time coefficients can be obtained, which can provide key coefficient support for calculating the electric field strength. Finally, by further calculating the obtained time coefficients, the electric field strength, current density, and magnetic field strength of each grid cell and each time step can be obtained, thus obtaining the core electromagnetic physical quantities in the transient process of lightning strike.

[0038] Further, the step of obtaining the simulated voltage data and simulated current data corresponding to the grid cell based on the electric field strength, preset reference conductivity, preset reference temperature, magnetic field strength, current density, structural material parameters, and preset material yield threshold of the grid cell includes: Based on the electric field strength, preset reference conductivity, preset reference temperature, magnetic field strength, current density, and structural material parameters corresponding to the grid cell, the stress field corresponding to the grid cell is solved. Based on the stress field and the preset material yield threshold, the fatigue damage factor corresponding to the grid cell is calculated, and the device lifetime within the corresponding grid cell is predicted based on the fatigue damage factor. Based on the device lifetime and the preset standard device lifetime, the corresponding lifetime difference is obtained. If the lifetime difference is greater than or equal to the preset lifetime threshold, the preset grid size or material electromagnetic parameters are adjusted, and the device lifetime in the corresponding grid cell is re-predicted until the lifetime difference is less than the preset lifetime threshold. Then, based on the electric field strength, current density, and magnetic field strength of the grid cell, the simulated voltage data and simulated current data of the grid cell are obtained.

[0039] In this embodiment, the stress field of each grid element is obtained by combining the electric field strength, preset reference conductivity, preset reference temperature, magnetic field strength, current density, and structural material parameters. This provides a mechanical analysis basis for subsequent life assessment. Next, by inputting the solved stress field into a preset material fatigue model, the fatigue damage factor is calculated using Miner's rule (the linear cumulative fatigue damage hypothesis) and a preset material yield threshold. This quantifies the cumulative damage degree of the device caused by lightning transient stress and predicts the device life within the corresponding mesh cell, thus realizing the transformation from mechanical analysis to life assessment. Finally, by calculating the life difference between the device life and the preset standard device life, if the life difference is greater than or equal to the preset life threshold, it indicates that there is room for optimization in the current mesh size or material electromagnetic parameters. The preset mesh size or material electromagnetic parameters are adjusted, and the device life is re-predicted using the adjusted preset mesh size and material electromagnetic parameters until the life difference is less than the preset life threshold. That is, under the premise that the device life meets the requirements, simulated voltage and current data with both electrical accuracy and life safety are obtained based on electric field strength and current density.

[0040] Further, the step of solving the stress field corresponding to the grid cell based on the electric field strength, preset reference conductivity, preset reference temperature, magnetic field strength, current density, and structural material parameters corresponding to the grid cell includes: The Joule heat source is calculated based on the electric field intensity corresponding to the grid cell, and the three-dimensional heat conduction equation is solved based on the Joule heat source to obtain the temperature field corresponding to the grid cell. Based on the temperature field, the preset reference conductivity, and the preset reference temperature, calculate the conductivity corresponding to the grid cell. Based on the conductivity, the magnetic field strength corresponding to the grid cell, and the current density corresponding to the grid cell, the electromagnetic force distribution corresponding to the grid cell is solved. Based on the electromagnetic force distribution and the structural material parameters corresponding to the grid cell, a three-dimensional elasticity equation is established, and the stress field corresponding to the grid cell is solved based on the three-dimensional elasticity equation.

[0041] In this embodiment, the Joule heat source of each grid cell is obtained by calculating the electric field intensity. The specific process is as follows: , This represents the Joule heat source of each grid cell. Represents the conductivity at a given moment , The electric field intensity is obtained by substituting it into the three-dimensional electromagnetic field partial differential model; then, the Joule heat source is substituted into the three-dimensional heat conduction equation to solve for the temperature field: ,in Indicates the density of the material; Specific heat capacity is represented by k; thermal conductivity is represented by k. This represents the local Joule heat source obtained from the electromagnetic field calculation. This represents the temperature field, providing temperature data support for subsequent conductivity calculations. Next, the temperature-corrected conductivity is calculated using the temperature field, a preset reference conductivity, and a preset reference temperature: (The last sentence appears to be incomplete and possibly refers to a different topic.) The relationship between temperature T and temperature is generally linear or approximately linear: in , For reference only. The temperature coefficient is set empirically; composite insulators or ceramic insulators... It also exhibits weak temperature dependence. Therefore, the temperature-corrected conductivity can be obtained through this process, ensuring dynamic matching between the material's electromagnetic properties and the temperature field in subsequent electromagnetic force calculations. Then, the electromagnetic force distribution of each grid cell is obtained by solving for conductivity, magnetic field strength, and current density. The specific process is as follows: First, the electromagnetic force distribution experienced by the conductor and fittings during the lightning transient is calculated according to the Lorentz force formula. ,in, , representing magnetic flux density. Indicates the permeability distribution. Indicates magnetic field strength; , represents the current density source term, and E represents the electric field strength. The conductivity is used to determine the magnitude and spatial distribution of the electromagnetic load on the structure during a lightning strike transient. Finally, by solving for the electromagnetic force distribution and structural material parameters, a three-dimensional elasticity equation is established: in This refers to the density of the structural material in the structural material parameters; Represents the displacement vector; Represents the strain tensor; The fourth-order elastic stiffness tensor is represented (at the fitting-tower interface, a contact spring-damping model can be set to evaluate loosening or changes in contact resistance caused by high impact forces), and the equation is solved to obtain the stress field of each mesh element. This completes the analysis and transformation from electromagnetic load to mechanical stress. Based on the obtained temperature and stress fields, the regions with the maximum temperature rise and stress concentration areas can be identified, allowing for comparison with preset material heat resistance and fatigue resistance parameters to label potential fault mesh elements.

[0042] This embodiment provides a transient analysis system for lightning strikes on high-voltage transmission lines, including a parameter acquisition module, a model building module, a spatiotemporal discretization module, a structural material parameter acquisition module, a lightning strike transient simulation module, and a model verification module, specifically: The parameter acquisition module is used to acquire transmission line parameters, material electromagnetic parameters, and atmospheric lightning strike channel parameters; The model building module is used to construct an initial three-dimensional electromagnetic field partial differential model corresponding to several grid units based on transmission line parameters, material electromagnetic parameters and preset grid size, and to obtain a three-dimensional electromagnetic field partial differential model corresponding to several grid units based on the initial three-dimensional electromagnetic field partial differential model corresponding to several grid units, atmospheric lightning channel parameters, preset waveform, preset disturbance, preset contact area and preset time step. The spatiotemporal discretization module is used to perform the following steps on the three-dimensional electromagnetic field partial differential model corresponding to any grid cell: spatiotemporally discretize the three-dimensional electromagnetic field partial differential model corresponding to the grid cell to obtain the electric field intensity, the current density and the magnetic field intensity corresponding to the grid cell. The structural material parameter acquisition module is used to acquire the structural material parameters corresponding to the grid unit; The lightning transient simulation module is used to obtain the simulation voltage data and simulation current data of the grid cell based on the electric field strength, preset reference conductivity, preset reference temperature, magnetic field strength, current density, structural material parameters and preset material yield threshold of the grid cell. The model verification module is used to acquire the measured data corresponding to the grid cell, and calculate the rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error based on the measured data, simulated voltage data, and simulated current data corresponding to the grid cell. If the rise time error is less than or equal to a preset time threshold, the peak amplitude error is less than or equal to a preset amplitude error threshold, and the high-frequency component amplitude-frequency response error is less than or equal to a preset amplitude-frequency response error threshold, then the three-dimensional electromagnetic field partial differential model corresponding to the grid cell is determined to meet the preset convergence condition, thereby achieving accurate simulation of the transient process of lightning strike on high-voltage transmission lines through the three-dimensional electromagnetic field partial differential model.

[0043] This embodiment provides a transient analysis system for lightning strikes on high-voltage transmission lines. In practical applications, it only requires a parameter acquisition module to obtain the geometric surfaces and volume elements of the towers and accessories using CAD modeling or high-precision 3D laser scanning. Simultaneously, it interpolates the conductor cross-sections according to the actual diameter, span, and sag shape to generate spatial curves, and models the insulator strings and fittings according to their actual dimensions and arrangement, thereby obtaining transmission line parameters. By acquiring transmission line parameters, material electromagnetic parameters, and atmospheric lightning strike channel parameters, it provides basic input data for constructing a 3D electromagnetic field partial differential model. Next, a model construction module is used to build an initial 3D electromagnetic field partial differential model corresponding to several grid cells. The high-voltage transmission line and surrounding area are discretized, and the complex overall electromagnetic field is decomposed into multiple computable grid cells. Then, by combining atmospheric lightning strike channel parameters, preset waveforms, preset disturbances, preset contact areas, and preset time steps, the initial 3D electromagnetic field partial differential model is optimized and adjusted to obtain 3D electromagnetic field partial differential models corresponding to several grid cells, making the model more closely reflect the electromagnetic field variation patterns under actual lightning strike scenarios. Then, using a spatiotemporal discretization module, the key physical quantities of electric field strength, current density, and magnetic field strength during the lightning strike transient process are obtained by spatiotemporally discretizing the three-dimensional electromagnetic field partial differential model corresponding to any grid cell. A structural material parameter acquisition module is then used to acquire structural material parameters, providing structural-level parameter basis for subsequent multiphysics coupling analysis and simulation data calculation. Subsequently, a lightning strike transient simulation module is used, combining electric field strength, preset reference conductivity, preset reference temperature, magnetic field strength, current density, structural material parameters, and preset material yield threshold. The experimentally measured waveform is imported into the three-dimensional electromagnetic field partial differential model of this embodiment, and simulations under the same conditions are performed to obtain simulated voltage data. and simulated current data This reflects the electrical impact of lightning strikes on power lines. Further, a model verification module was used to obtain experimental data in the laboratory. Specifically, the test setup employed a pulse generator conforming to IEC / IEEE standards, capable of outputting 8 / 20... With 10 / 350 Two typical lightning strike waveforms are tested, with a maximum current amplitude of up to 200 kA. The test sample is a scaled-down model consisting of a conductor segment, insulator string, and fittings, manufactured at a scale of 1:10 or 1:20 while maintaining electrical equivalence. High-speed current transformers (bandwidth ≥ 10 MHz) and voltage probes are installed at both ends of the conductor and key nodes of the insulator string, respectively. Test procedure: Set the waveform and amplitude, and apply the voltage to the input terminal of the test piece through a step-up transformer; synchronously trigger data acquisition and record the measured current data. Compared with measured voltage data By comparing the measured current data with the simulated current data, and the measured voltage data with the simulated voltage data, through... The rise time error is obtained (where, Indicates rise time error. This indicates the rise time of the measured lightning current. (representing the simulated rise time of the lightning current), through The peak amplitude error is obtained (where, Indicates the peak amplitude error. This represents the maximum peak current measured by lightning. The maximum peak current obtained through numerical simulation and the high-frequency component amplitude-frequency response error obtained through FFT analysis of the waveform are used to verify the accuracy of the three-dimensional electromagnetic field partial differential model. If the rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error all meet the corresponding preset thresholds, specifically: rise time error Peak amplitude error And the amplitude-frequency response error of the high-frequency components does not exceed This confirms that the three-dimensional electromagnetic field partial differential model meets the preset convergence conditions, avoiding inaccurate risk positioning due to insufficient accuracy of simplified circuit models. It enables high-precision, full-domain simulation of the transient lightning strike process on high-voltage transmission lines, providing reliable data support for lightning protection design optimization. This embodiment achieves full-space, full-time dynamic visualization of the electric field, magnetic field, and current distribution under lightning transients, overcoming the shortcomings of traditional lumped parameter or quasi-static models that cannot accurately describe spatial distribution effects and the influence of non-uniform medium boundaries.

[0044] Furthermore, the model verification module is also used for: If the rise time error is greater than the preset time threshold, or the peak amplitude error is greater than the preset amplitude error threshold, or the high-frequency component amplitude-frequency response error is greater than the preset amplitude-frequency response error threshold, then the preset mesh size, material electromagnetic parameters, or preset time step are adjusted, and the rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error are recalculated until the preset convergence condition is met, and the three-dimensional electromagnetic field partial differential model corresponding to the mesh element is obtained.

[0045] In this embodiment, if any of the rise time error, peak amplitude error, or high-frequency component amplitude-frequency response error exceeds the standard, the three-dimensional electromagnetic field partial differential model is determined to require optimization. Next, after determining that the three-dimensional electromagnetic field partial differential model needs optimization, the input parameters of the three-dimensional electromagnetic field partial differential model are optimized by specifically adjusting the preset mesh size, material electromagnetic parameters, or preset time step, thereby improving simulation accuracy. Then, using the adjusted preset mesh size, material electromagnetic parameters, or preset time step, the rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error are recalculated to verify the improvement effect on the accuracy of the three-dimensional electromagnetic field partial differential model. Finally, by repeatedly executing the parameter adjustment and error recalculation process until the rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error all meet the corresponding preset thresholds, a three-dimensional electromagnetic field partial differential model that meets the preset convergence conditions is obtained.

[0046] Furthermore, the model building module is used to construct an initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells based on transmission line parameters, material electromagnetic parameters, and a preset grid size, and to obtain a three-dimensional electromagnetic field partial differential model corresponding to several grid cells based on the initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells, atmospheric lightning channel parameters, preset waveform, preset disturbance, preset contact area, and preset time step; including: Based on transmission line parameters, material electromagnetic parameters, and preset mesh size, an initial three-dimensional electromagnetic field partial differential model corresponding to several mesh elements is constructed. Obtain atmospheric lightning strike channel parameters; Based on atmospheric lightning channel parameters, a lightning channel transmission line model is constructed; An initial lightning strike current is generated based on a preset waveform and a preset disturbance. Based on the preset contact area and initial lightning current, a current density source term is constructed; Based on a preset time step, the initial three-dimensional electromagnetic field partial differential model and the lightning strike channel transmission line model are synchronized in time. Based on the time-synchronized initial three-dimensional electromagnetic field partial differential model and the current density source term, the three-dimensional electromagnetic field partial differential models corresponding to several grid cells are obtained.

[0047] In this embodiment, an initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells is constructed by combining transmission line parameters, material electromagnetic parameters, and preset grid sizes. This allows for the discretization and modeling of the high-voltage transmission line and its surrounding space, decomposing the complex three-dimensional electromagnetic field into multiple grid cells, thus laying the foundation model framework for the subsequent introduction of lightning-related conditions. Next, a lightning channel transmission line model is established using atmospheric lightning channel parameters. in For the distributed inductance of the air channel, For the distributed capacitance of the air channel, For the distributed resistance of the air channel, The distributed conductivity of the air channel is a parameter of the atmospheric lightning strike channel; Let be the current intensity at time t and channel height (coordinate z); Let be the voltage at time t and channel height (coordinate z); thus simplifying the atmospheric lightning channel into a one-dimensional transmission line that satisfies the Telegrapher equation, enabling a mathematical description of the lightning current propagation process. Then, through the top of the cloud... Apply lightning strike voltage or a preset waveform (IEC typical waveform (8 / 20µs, 10 / 350µs) or measured waveform) and a preset disturbance (Gaussian white noise). Or random disturbances measured in the field, such as ,in The disturbance intensity coefficient is... This is the initial lightning strike current. To add Gaussian white noise The lightning current after the strike is obtained by integrating the PDE downwards with depth z. —The lightning current waveform reaching the contact point of the lightning protection wire is generated to produce an initial lightning current that matches the actual lightning strike scenario. This is used to simulate waveform uncertainties in a thunderstorm environment and provide a realistic excitation source. Subsequently, based on the preset contact area and the initial lightning current, a current density source term is constructed. Specifically, the generated initial lightning current is... The current at the location constructs the current density source term: ,in The Dirac distribution is shown along the contact area (preset contact area) of the lightning protection wire, where t is the tangential vector of the conductor. To predetermine the contact area (or the total curve length), the initial lightning current is transformed into a source term that can be injected into a three-dimensional electromagnetic field model. This ensures the conservation of current incidence and total flow rate along the path within the domain. Finally, the initial three-dimensional electromagnetic field partial differential model and the lightning channel transmission line model were synchronized by setting a preset time step: the time step of the lightning channel transmission line model was calculated respectively. With respect to the time step of the partial differential model of electromagnetic field Each of them satisfies the CFL condition, and then the smallest one is taken as the global step size: If the one-dimensional waveform (lightning transmission line model) changes drastically, the amount of [something] can be temporarily reduced. To ensure spatiotemporal synchronization. The synchronization strategy between the lightning strike channel transmission line model and the three-dimensional electromagnetic field partial differential model: at the same global instant... Iterate; at each time step, first calculate on a one-dimensional channel. Then, it is injected into the three-dimensional electromagnetic field partial differential model for electric field update, thereby ensuring the consistency of the calculation of the two models in the time dimension; at the same time, the current density source term is integrated into the initial three-dimensional electromagnetic field partial differential model after time synchronization, and finally the three-dimensional electromagnetic field partial differential model corresponding to several grid cells is obtained, so that the model can fully reflect the dynamic changes of the electromagnetic field during the transient process of lightning strike.

[0048] This embodiment can also integrate online monitoring and early warning. The monitoring platform architecture has a data layer, a computing layer, and a display layer. The data layer is used to report real-time data from sensor nodes along the line (current transformers, voltage probes, partial discharge detectors) via fiber optic communication. The computing layer is used to deploy high-performance clusters or GPU servers to run lightweight three-dimensional electromagnetic field partial differential models and lightning strike channel transmission line models. The display layer is used to display the overvoltage and overcurrent distribution maps and risk levels of each tower in real time through a visual interface. This embodiment also provides a rapid early warning algorithm: It extracts feature indicators such as rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error by performing wavelet decomposition or short-time Fourier transform on the real-time sampled waveform. When any feature indicator exceeds its corresponding preset threshold, the current three-dimensional electromagnetic field partial differential model is fine-tuned until the simulated feature indicators are within the preset threshold, indicating that the three-dimensional electromagnetic field partial differential model can accurately simulate the corresponding high-voltage transmission line lightning transient process. Risk assessment: The simulation results are compared with safety limits (insulator withstand voltage, fitting thermal load limit, etc.) to generate the corresponding risk level (low / medium / high). Finally, this embodiment can also provide operation and maintenance decision support: It can automatically generate inspection routes and key inspection areas based on a list of high-risk towers and provide inspection suggestions; it can propose design optimization suggestions such as lightning protection wire installation height, grounding resistance, and lightning protection wire cross-section based on long-term statistical results; and it can form a database of event waveforms, simulation results, and operation and maintenance strategies for subsequent model calibration and life prediction.

[0049] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A transient analysis method for lightning strikes on high-voltage transmission lines, characterized in that, include: Obtain transmission line parameters, material electromagnetic parameters, and atmospheric lightning strike channel parameters; Based on transmission line parameters, material electromagnetic parameters, and preset grid size, an initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells is constructed. Based on the initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells, atmospheric lightning channel parameters, preset waveform, preset disturbance, preset contact area, and preset time step, a three-dimensional electromagnetic field partial differential model corresponding to several grid cells is obtained. For any three-dimensional electromagnetic partial differential model corresponding to a grid cell, the following steps are performed: the three-dimensional electromagnetic partial differential model corresponding to the grid cell is discretized in time and space to obtain the electric field intensity, the current density, and the magnetic field intensity corresponding to the grid cell. Obtain the structural material parameters corresponding to the mesh element; Based on the electric field strength, preset reference conductivity, preset reference temperature, magnetic field strength, current density, structural material parameters, and preset material yield threshold of the grid cell, the simulated voltage data and simulated current data of the grid cell are obtained. Obtain the measured data corresponding to the grid cell, and calculate the rise time error, peak amplitude error and high-frequency component amplitude-frequency response error based on the measured data, simulated voltage data and simulated current data corresponding to the grid cell. If the rise time error is less than or equal to the preset time threshold, the peak amplitude error is less than or equal to the preset amplitude error threshold, and the high-frequency component amplitude-frequency response error is less than or equal to the preset amplitude-frequency response error threshold, then the three-dimensional electromagnetic field partial differential model corresponding to the grid cell is determined to meet the preset convergence condition, thereby realizing the accurate simulation of the transient process of lightning strike on high-voltage transmission lines through the three-dimensional electromagnetic field partial differential model.

2. The transient analysis method for lightning strikes on high-voltage transmission lines according to claim 1, characterized in that, Also includes: If the rise time error is greater than the preset time threshold, or the peak amplitude error is greater than the preset amplitude error threshold, or the high-frequency component amplitude-frequency response error is greater than the preset amplitude-frequency response error threshold, then the preset mesh size, material electromagnetic parameters, or preset time step are adjusted, and the rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error are recalculated until the preset convergence condition is met, and the three-dimensional electromagnetic field partial differential model corresponding to the mesh element is obtained.

3. The transient analysis method for lightning strikes on high-voltage transmission lines according to claim 1, characterized in that, The process involves constructing an initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells based on transmission line parameters, material electromagnetic parameters, and a preset grid size. Then, based on this initial three-dimensional electromagnetic field partial differential model, atmospheric lightning channel parameters, preset waveforms, preset disturbances, preset contact areas, and preset time steps, a three-dimensional electromagnetic field partial differential model corresponding to several grid cells is obtained. This includes: Based on transmission line parameters, material electromagnetic parameters, and preset mesh size, an initial three-dimensional electromagnetic field partial differential model corresponding to several mesh elements is constructed. Obtain atmospheric lightning strike channel parameters; Based on atmospheric lightning channel parameters, a lightning channel transmission line model is constructed; An initial lightning strike current is generated based on a preset waveform and a preset disturbance. Based on the preset contact area and initial lightning current, a current density source term is constructed; Based on a preset time step, the initial three-dimensional electromagnetic field partial differential model and the lightning strike channel transmission line model are synchronized in time. Based on the time-synchronized initial three-dimensional electromagnetic field partial differential model and the current density source term, the three-dimensional electromagnetic field partial differential models corresponding to several grid cells are obtained.

4. The transient analysis method for lightning strikes on high-voltage transmission lines according to claim 3, characterized in that, The method involves constructing an initial three-dimensional electromagnetic field partial differential model corresponding to several grid elements based on transmission line parameters, material electromagnetic parameters, and a preset grid size; including: Construct the initial computational domain; Based on the transmission line parameters and the initial computational domain, a three-dimensional computational domain is obtained; Based on the preset mesh size, the three-dimensional computational domain is meshed to obtain several mesh elements; The material's electromagnetic parameters are mapped to the corresponding mesh elements, and an initial three-dimensional electromagnetic field partial differential model corresponding to several mesh elements is constructed based on the preset Maxwell's time-domain equations and the material's electromagnetic parameters.

5. The transient analysis method for lightning strikes on high-voltage transmission lines according to claim 1, characterized in that, For any given grid cell, the following steps are performed on the three-dimensional electromagnetic field partial differential model: the three-dimensional electromagnetic field partial differential model corresponding to the grid cell is spatiotemporally discretized to obtain the electric field intensity, current density, and magnetic field intensity corresponding to the grid cell; including: The three-dimensional electromagnetic field partial differential model corresponding to the mesh element is spatially discretized to construct the stiffness matrix, mass matrix, and excitation vector corresponding to the mesh element. Based on the stiffness matrix, the mass matrix, the excitation vector, and the three-dimensional electromagnetic partial differential model corresponding to the mesh element, the system of ordinary differential equations corresponding to the mesh element is obtained. Discretize and solve the system of ordinary differential equations in time to obtain the discrete linear model corresponding to the grid cell; Based on the discrete linear model and the preset solver, the time coefficient corresponding to the grid cell is obtained; Based on the time coefficient, the electric field strength, current density, and magnetic field strength corresponding to the grid cell are obtained.

6. The transient analysis method for lightning strikes on high-voltage transmission lines according to claim 4, characterized in that, The simulation voltage data and simulation current data of the grid cell are obtained based on the electric field strength, preset reference conductivity, preset reference temperature, magnetic field strength, current density, structural material parameters and preset material yield threshold of the grid cell. include: Based on the electric field strength, preset reference conductivity, preset reference temperature, magnetic field strength, current density, and structural material parameters corresponding to the grid cell, the stress field corresponding to the grid cell is solved. Based on the stress field and the preset material yield threshold, the fatigue damage factor corresponding to the grid cell is calculated, and the device lifetime within the corresponding grid cell is predicted based on the fatigue damage factor. Based on the device lifetime and the preset standard device lifetime, the corresponding lifetime difference is obtained. If the lifetime difference is greater than or equal to the preset lifetime threshold, the preset grid size or material electromagnetic parameters are adjusted, and the device lifetime in the corresponding grid cell is re-predicted until the lifetime difference is less than the preset lifetime threshold. Then, based on the electric field strength, current density, and magnetic field strength of the grid cell, the simulated voltage data and simulated current data of the grid cell are obtained.

7. The transient analysis method for lightning strikes on high-voltage transmission lines according to claim 6, characterized in that, The process of solving the stress field corresponding to a grid cell based on the electric field strength, preset reference conductivity, preset reference temperature, magnetic field strength, current density, and structural material parameters of that grid cell includes: The Joule heat source is calculated based on the electric field intensity corresponding to the grid cell, and the three-dimensional heat conduction equation is solved based on the Joule heat source to obtain the temperature field corresponding to the grid cell. Based on the temperature field, the preset reference conductivity, and the preset reference temperature, calculate the conductivity corresponding to the grid cell. Based on the conductivity, the magnetic field strength corresponding to the grid cell, and the current density corresponding to the grid cell, the electromagnetic force distribution corresponding to the grid cell is solved. Based on the electromagnetic force distribution and the structural material parameters corresponding to the grid cell, a three-dimensional elasticity equation is established, and the stress field corresponding to the grid cell is solved based on the three-dimensional elasticity equation.

8. A transient analysis system for lightning strikes on high-voltage transmission lines, characterized in that, It includes a parameter acquisition module, a model building module, a spatiotemporal discretization module, a structural material parameter acquisition module, a lightning strike transient simulation module, and a model verification module, specifically: The parameter acquisition module is used to acquire transmission line parameters, material electromagnetic parameters, and atmospheric lightning strike channel parameters; The model building module is used to construct an initial three-dimensional electromagnetic field partial differential model corresponding to several grid units based on transmission line parameters, material electromagnetic parameters and preset grid size, and to obtain a three-dimensional electromagnetic field partial differential model corresponding to several grid units based on the initial three-dimensional electromagnetic field partial differential model corresponding to several grid units, atmospheric lightning channel parameters, preset waveform, preset disturbance, preset contact area and preset time step. The spatiotemporal discretization module is used to perform the following steps on the three-dimensional electromagnetic field partial differential model corresponding to any grid cell: spatiotemporally discretize the three-dimensional electromagnetic field partial differential model corresponding to the grid cell to obtain the electric field intensity, the current density and the magnetic field intensity corresponding to the grid cell. The structural material parameter acquisition module is used to acquire the structural material parameters corresponding to the grid unit; The lightning transient simulation module is used to obtain the simulation voltage data and simulation current data of the grid cell based on the electric field strength, preset reference conductivity, preset reference temperature, magnetic field strength, current density, structural material parameters and preset material yield threshold of the grid cell. The model verification module is used to acquire the measured data corresponding to the grid cell, and calculate the rise time error, peak amplitude error and high-frequency component amplitude-frequency response error based on the measured data, simulated voltage data and simulated current data corresponding to the grid cell. If the rise time error is less than or equal to the preset time threshold, the peak amplitude error is less than or equal to the preset amplitude error threshold, and the high-frequency component amplitude-frequency response error is less than or equal to the preset amplitude-frequency response error threshold, then the three-dimensional electromagnetic field partial differential model corresponding to the grid cell is determined to meet the preset convergence condition, thereby realizing the accurate simulation of the transient process of lightning strike on high-voltage transmission lines through the three-dimensional electromagnetic field partial differential model.

9. A transient analysis system for lightning strikes on high-voltage transmission lines according to claim 8, characterized in that, The model validation module is also used for: If the rise time error is greater than the preset time threshold, or the peak amplitude error is greater than the preset amplitude error threshold, or the high-frequency component amplitude-frequency response error is greater than the preset amplitude-frequency response error threshold, then the preset mesh size, material electromagnetic parameters, or preset time step are adjusted, and the rise time error, peak amplitude error, and high-frequency component amplitude-frequency response error are recalculated until the preset convergence condition is met, and the three-dimensional electromagnetic field partial differential model corresponding to the mesh element is obtained.

10. A transient analysis system for lightning strikes on high-voltage transmission lines according to claim 9, characterized in that, The model building module is used to construct an initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells based on transmission line parameters, material electromagnetic parameters, and a preset grid size. Based on the initial three-dimensional electromagnetic field partial differential model corresponding to several grid cells, atmospheric lightning channel parameters, preset waveforms, preset disturbances, preset contact areas, and preset time steps, it obtains a three-dimensional electromagnetic field partial differential model corresponding to several grid cells; including: Based on transmission line parameters, material electromagnetic parameters, and preset mesh size, an initial three-dimensional electromagnetic field partial differential model corresponding to several mesh elements is constructed. Obtain atmospheric lightning strike channel parameters; Based on atmospheric lightning channel parameters, a lightning channel transmission line model is constructed; An initial lightning strike current is generated based on a preset waveform and a preset disturbance. Based on the preset contact area and initial lightning current, a current density source term is constructed; Based on a preset time step, the initial three-dimensional electromagnetic field partial differential model and the lightning strike channel transmission line model are synchronized in time. Based on the time-synchronized initial three-dimensional electromagnetic field partial differential model and the current density source term, the three-dimensional electromagnetic field partial differential models corresponding to several grid cells are obtained.

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