Simulation analysis method and system for step voltage gradient of grounding grid in lightning strike scenario

Abstract

The application discloses a lightning stroke scene ground net step voltage gradient simulation analysis method and system. The method comprises the following steps: acquiring lightning current parameters of a lightning stroke scene and physical structure parameters of a ground net; based on the parameters, a three-dimensional simulation model of the ground net is established by using electromagnetic field simulation software, and a lightning current signal is subjected to frequency domain decomposition processing; based on the simulation model, a step voltage calculation model is used for theoretical calculation to obtain step voltage distribution data; combined with human body impedance characteristics and a safety current threshold, time domain response calculation and safety evaluation analysis are carried out to obtain the maximum step voltage borne by the human body. The application realizes accurate simulation and safety evaluation of lightning stroke step voltage by combining time-frequency domain joint simulation with theoretical calculation, and provides reliable technical support for lightning protection and grounding design of large venues and other places.

Description

Technical Field

[0001] This invention relates to the field of building lightning protection and electromagnetic compatibility technology, and in particular to a method and system for simulating and analyzing the step voltage gradient of the grounding grid in a lightning strike scenario. Background Technology

[0002] In the field of lightning protection engineering, the safety assessment of the grounding grid is a core link in ensuring the safety of personnel and equipment. With the continuous expansion of the construction scale of infrastructure such as large stadiums and data centers, the electromagnetic transient characteristics of their grounding systems under the action of lightning transient high current have become particularly complex. Traditional power frequency grounding resistance measurement methods are no longer able to accurately reflect the impact of the high-frequency transient process of lightning on the potential distribution of the grounding grid. This can lead to extremely high step voltage gradients on the ground surface during lightning strikes, posing a fatal threat to on-site personnel. Although there are some analysis methods based on simulation software in the existing technology, they are often limited to static resistivity calculations or simplified circuit models. They lack a comprehensive consideration of the coupling effect between the time-frequency domain characteristics of lightning current and the three-dimensional structure of the grounding grid, making it difficult to accurately simulate the complex electromagnetic field distribution generated when lightning current diffuses in the soil. Moreover, the dynamic correlation between human body impedance and safe current threshold is usually ignored in the assessment process, resulting in a large deviation between the safety assessment results and the actual working conditions. Therefore, there is an urgent need for a high-precision simulation analysis method that can comprehensively consider the characteristics of lightning current waveform, the physical structure of the grounding grid, and human safety characteristics to achieve accurate prediction and risk assessment of step voltage gradients under lightning strike scenarios. Summary of the Invention

[0003] The purpose of this invention is to provide a method and system for simulating and analyzing the step voltage gradient of the grounding grid in a lightning strike scenario. This addresses the technical problems in the existing technology, such as the lack of accurate simulation methods for the coupling effect and distribution pattern of lightning electromagnetic pulses in complex building spaces, which makes it difficult to accurately identify dangerous areas of sensitive internal equipment; and the lack of guidance based on quantitative magnetic field distribution data in existing protection designs, which makes it difficult to generate targeted spatial layout optimization and hierarchical shielding grounding strategies, resulting in insufficient effectiveness of protection measures.

[0004] To achieve the above objectives, a method for simulating and analyzing the step voltage gradient of a grounding grid in a lightning strike scenario is provided in a first aspect of the present invention, comprising the following steps:

[0005] Obtain the lightning current parameters and the physical structure parameters of the grounding grid in the lightning strike scenario;

[0006] Based on the lightning current parameters and the physical structure parameters, a three-dimensional simulation model of the grounding grid is established using electromagnetic field simulation software, and the lightning current signal is processed by frequency domain decomposition.

[0007] Based on the simulation model, the step voltage calculation model is used to theoretically calculate the step voltage of lightning strikes and obtain the step voltage distribution data.

[0008] By combining the human body impedance characteristics and safe current threshold, the step voltage time domain response is calculated using the frequency domain decomposition results. The safety assessment and analysis of the step voltage distribution data are then performed to obtain the maximum step voltage that the human body can withstand.

[0009] Furthermore, the lightning current parameters include lightning current amplitude, wavefront time, and half-value time; the lightning current amplitude, wavefront time, and half-value time are set according to the standard lightning current waveform.

[0010] Furthermore, the theoretical calculation of the lightning strike step voltage using the step voltage calculation model specifically includes:

[0011] For irregular grounding grids, the Thapar formula is used to obtain step voltage distribution data. In the Thapar formula, the step voltage is related to soil resistivity, maximum current flowing through the grounding electrode, maximum diagonal length of the grounding grid, conductor diameter, burial depth of the grounding electrode, spacing between parallel conductors, and number of parallel conductors in one direction of the grounding grid.

[0012] Furthermore, the maximum step voltage that the human body can withstand is specifically calculated using the following formula:

[0013] When the building is surrounded by soil, the maximum step voltage that the human body can withstand is calculated using the following formula:

[0014]

[0015] Among them, Rb represents the human body resistance, with two values: Rb = 1000Ω and 1500Ω, and ρ represents the soil resistivity.

[0016] When the building is surrounded by soil, the maximum step voltage that the human body can withstand is calculated using the following formula:

[0017]

[0018]

[0019] ρ S The resistivity of the upper concrete layer is ρ when dry. S =2000Ω·m; ρ is the resistivity of the underlying soil in Ω·m; D is the thickness of the concrete.

[0020] Furthermore, the safe current for the human body is set according to the weight of the human body, with different human body weights corresponding to different safe current thresholds.

[0021] Furthermore, the human body resistance is set to a corresponding impedance value based on the lightning current impact or the power frequency voltage safety design.

[0022] Furthermore, the step of establishing a three-dimensional simulation model of the grounding grid using electromagnetic field simulation software and performing frequency domain decomposition processing on the lightning current signal specifically includes:

[0023] The grounding grid modeling tool is used for modeling. The frequency domain calculation module is used to perform frequency domain decomposition of the lightning current time domain signal and step voltage frequency domain response calculation. Finally, the time domain conversion module is used to calculate the step voltage time domain response.

[0024] Furthermore, the lightning strike scenario is a large sports stadium, and the physical structural parameters include the total length of the grounding grid, the total length of the perimeter of the grounding grid, and the area of ​​the grounding grid.

[0025] Secondly, the present invention provides a system for simulating and analyzing the step voltage gradient of a grounding grid in a lightning strike scenario, comprising:

[0026] The parameter acquisition module is used to acquire the lightning current parameters and the physical structure parameters of the grounding grid in the lightning strike scenario;

[0027] The model building module is used to construct models based on the lightning current parameters and the physical structure parameters, utilizing electromagnetic...

[0028] The simulation software establishes a three-dimensional simulation model of the grounding grid and performs frequency domain decomposition processing on the lightning current signal;

[0029] The voltage calculation module is used to calculate the step voltage of a lightning strike based on the simulation model using a step voltage calculation model.

[0030] The voltage is theoretically calculated to obtain step voltage distribution data;

[0031] The safety analysis module is used to combine human body impedance characteristics and safe current threshold, use frequency domain decomposition results to calculate step voltage time domain response, perform safety assessment analysis on the step voltage distribution data, and obtain the maximum step voltage that the human body can withstand.

[0032] Thirdly, the present invention also provides a computer-readable storage medium having a computer program stored thereon, characterized in that, when the program is executed by a processor, it implements the steps of the grounding grid step voltage gradient simulation analysis method in any of the lightning strike scenarios described in the present invention.

[0033] The beneficial technical effects of the present invention are at least as follows:

[0034] This invention effectively solves the technical problems of insufficient transient response accuracy and ambiguous safety boundaries in traditional lightning protection assessment methods by constructing a multi-physics coupled analysis model of lightning strike scenarios and grounding grid structures. This innovative method jointly simulates the time-frequency domain characteristics of lightning current with the electromagnetic field distribution of a three-dimensional grounding grid. Through the collaborative calculation mechanism of frequency domain decomposition and time domain response, it can accurately capture the dynamic evolution of the ground surface potential gradient at the moment of lightning strike, significantly improving the accuracy of step voltage prediction compared to traditional power frequency calculation methods. In the safety assessment stage, by introducing a correlation analysis model between human body impedance characteristics and dynamic safe current thresholds, combined with the current dissipation law under different soil conditions, a graded risk assessment system is established. This ensures that lightning protection design meets the safety requirements under extreme lightning strike conditions while avoiding resource waste caused by over-protection. The systematic modular architecture design realizes fully automated processing from parameter acquisition and model construction to safety analysis, significantly shortening the simulation analysis cycle of large grounding grids. It provides high-precision and practical technical support for the optimization of lightning protection grounding for critical infrastructure such as stadiums and substations, effectively ensuring the safety of personnel and equipment in lightning strike scenarios. Attached Figure Description

[0035] The present invention will be further described with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the present invention. For those skilled in the art, other drawings can be obtained based on the following drawings without creative effort.

[0036] Figure 1 This is a flowchart illustrating the working steps of a grounding grid step voltage gradient simulation analysis method in a lightning strike scenario, as disclosed in one embodiment of the present invention.

[0037] Figure 2 This is a short-time lightning strike diagram disclosed in one embodiment of the present invention;

[0038] Figure 3 This is a long-term lightning strike diagram disclosed in one embodiment of the present invention;

[0039] Figure 4 This is a schematic diagram of a standard lightning current waveform with an amplitude of 150kA and a waveform of 10 / 350µs disclosed in one embodiment of the present invention;

[0040] Figure 5 This is a schematic diagram of the grounding grid step voltage gradient simulation analysis system in a lightning strike scenario, as disclosed in one embodiment of the present invention. Detailed Implementation

[0041] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0042] Example 1

[0043] refer to Figure 1 The present invention provides an embodiment for obtaining lightning current parameters and physical structure parameters of the grounding grid in a lightning strike scenario;

[0044] Based on the lightning current parameters and the physical structure parameters, a three-dimensional simulation model of the grounding grid is established using electromagnetic field simulation software, and the lightning current signal is processed by frequency domain decomposition.

[0045] Based on the simulation model, the step voltage calculation model is used to theoretically calculate the step voltage of lightning strikes and obtain the step voltage distribution data.

[0046] By combining the human body impedance characteristics and safe current threshold, the step voltage time domain response is calculated using the frequency domain decomposition results. The safety assessment and analysis of the step voltage distribution data are then performed to obtain the maximum step voltage that the human body can withstand.

[0047] This embodiment provides a method for simulating and analyzing the step voltage gradient of a grounding grid in a lightning strike scenario. The specific implementation steps are as follows: First, lightning current parameters such as the amplitude and waveform time parameters of the lightning current under the target lightning strike scenario are obtained through lightning monitoring data or a standard lightning waveform library. At the same time, physical structural parameters such as the size, burial depth, conductor specifications, and layout of the grounding grid are collected through engineering design drawings. Then, the above parameters are imported into electromagnetic field simulation software to construct a three-dimensional solid simulation model of the grounding grid consistent with the actual project. Based on the principle of fast Fourier transform, the time-domain signal of the lightning current is decomposed in the frequency domain to obtain the lightning current spectrum distribution under different frequency components. Next, based on the established simulation model, the built-in step voltage calculation model is called to perform point-by-point numerical calculation of the step voltage at various points on the ground surface after the lightning strike, generating a full-field step voltage distribution cloud map and discrete data. Finally, typical human impedance parameters and safe current limits are introduced, and the step voltage time-domain response is reconstructed by combining the frequency domain decomposition results. The step voltage at each point is compared and analyzed with the safe threshold to determine the maximum step voltage value that the human body may withstand during the lightning strike, thus completing the overall safety assessment.

[0048] Furthermore, the lightning current parameters include lightning current amplitude, wavefront time, and half-value time; the lightning current amplitude, wavefront time, and half-value time are set according to the standard lightning current waveform.

[0049] Table 5.1 Lightning current parameters of the first lightning strike

[0050]

[0051] Because the essential component of the total charge Qs is included in the first lightning strike, the specified value takes into account the charge of all short-duration lightning strikes. Similarly, because the essential component of the unit energy W / R is included in the first lightning strike, the specified value takes into account the unit energy of all short-duration lightning strikes.

[0052] Table 5.2 Lightning current parameters after the first lightning strike

[0053]

[0054] Table 5.3 Lightning current parameters of long-term lightning strikes

[0055]

[0056] In this embodiment, the lightning current parameters specifically include lightning current amplitude, wavefront time, and half-value time. During implementation, the lightning current waveform is set according to internationally accepted and domestic power industry standards. A standard double-exponential lightning current waveform is selected as the input excitation, and its amplitude, wavefront time, and half-value time are all taken within the standard specified range, without relying on specific fixed values. These values ​​can be adaptively adjusted according to different lightning strike levels, lightning protection zones, and project importance, thereby ensuring that the simulation analysis results have broad applicability and engineering representativeness.

[0057] Furthermore, the theoretical calculation of the lightning strike step voltage using the step voltage calculation model specifically includes:

[0058] For irregular grounding grids, the Thapar formula is used to obtain step voltage distribution data. In the Thapar formula, the step voltage is related to soil resistivity, maximum current flowing through the grounding electrode, maximum diagonal length of the grounding grid, conductor diameter, burial depth of the grounding electrode, spacing between parallel conductors, and number of parallel conductors in one direction of the grounding grid.

[0059] In this embodiment, when using the step voltage calculation model for theoretical calculations, Thapar's empirical formula is used to solve for the step voltage distribution for grounding grids with irregular shapes and asymmetrical arrangements. During implementation, parameters such as soil resistivity measured on-site or given in the design, maximum fault current flowing into the grounding electrode, maximum diagonal geometric length of the grounding grid, diameter of the grounding conductor, burial depth of the grounding electrode, spacing of parallel conductors, and number of parallel conductors in one direction of the grounding grid are substituted into the formula. Numerical calculations are then performed to obtain the step voltage value at any point on the ground surface, ultimately forming step voltage distribution data covering the entire grounding grid area. This method is suitable for rapid calculations in complex terrains and irregular grounding grid structures.

[0060] Furthermore, the maximum step voltage that the human body can withstand is specifically calculated using the following formula:

[0061] When the building is surrounded by soil, the maximum step voltage that the human body can withstand is calculated using the following formula:

[0062]

[0063] Among them, Rb represents the human body resistance, with two values: Rb = 1000Ω and 1500Ω, and ρ represents the soil resistivity.

[0064] When the building is surrounded by soil, the maximum step voltage that the human body can withstand is calculated using the following formula:

[0065]

[0066]

[0067] ρ S The resistivity of the upper concrete layer is ρ when dry. S =2000Ω·m; ρ is the resistivity of the underlying soil in Ω·m; D is the thickness of the concrete.

[0068] Furthermore, the safe current for the human body is set according to the weight of the human body, with different human body weights corresponding to different safe current thresholds.

[0069] The human body safety current is set and implemented in a graded manner based on human body weight. In specific implementation, a human body safety current threshold reference table is established according to different weight ranges. The larger the weight, the higher the corresponding safety current threshold, and the smaller the weight, the lower the safety current threshold. During the simulation analysis, the corresponding safety current value is selected according to the typical weight range of the target protected population, so that the safety assessment is more in line with the actual physiological characteristics of the human body, and the accuracy and rationality of the assessment results are improved.

[0070] When the human body weighs 50kg, the safe current for the human body is:

[0071]

[0072] When the human body weighs 70kg, the safe current for the human body is:

[0073]

[0074] The maximum step voltage that the human body can withstand is:

[0075] U kmax =I b R b

[0076]

[0077]

[0078] When performing safety design calculations for power frequency voltage, the human body resistance is generally taken as 400Ω. Under lightning current impact, the human body resistance exhibits different values ​​at different amplitudes and frequencies. According to research and experiments showing that "resistance decreases with increasing frequency, and skin impedance decreases with increasing current," and based on the view of the American IEEE, the human body impact resistance under lightning current impact is in the range of 300~500Ω.

[0079] The maximum UKmax value that the human body can withstand when the lightning current waveform is 10 / 350µs is shown in the table below.

[0080] Table 5.4 When the human body weight is 50kg

[0081]

[0082] Table 5.5 When the human body weight is 70kg

[0083]

[0084] Although lightning leader discharges are irregularly dendritic and develop in a pulsed manner, research shows that they still possess distributed parameter characteristics. They can be approximated as a conductive channel with evenly distributed inductance and capacitance parameters, called a lightning channel. Its surge impedance is Z0, typically taken as 300Ω. Considering the main generation process as an infinitely extending lightning channel with surge impedance Z0, and the traveling wave (U0=i0Z0) from the sky to the ground, when lightning strikes an object, the current flowing through the struck object can be calculated using the Petersen equivalent circuit: i=2i0[Z0 / (Z0+Z)], where Z is the surge impedance of the struck object.

[0085] When Z≪Z0, generally when Z<30Ω, i≈2i0 can be taken.

[0086] When lightning current strikes a building directly, the distribution of the lightning current in the building's metal frame is related to the location of the lightning strike point, the structure of the lightning arrester and grounding grid, the distribution of the down conductors, and the magnitude of the grounding impedance.

[0087] When lightning strikes a building, the shunt coefficient of its down conductor can be simplified and determined according to Appendix E of GB50057-2010.

[0088] The shunt coefficient is 1 for a single down conductor, 0.66 for two down conductors or multiple down conductors that do not form a closed loop with the lightning arrester, and 0.44 for multiple down conductors that form a closed loop or a mesh-like structure with the lightning arrester. When using a mesh-type lightning arrester, the down conductors are interconnected by multiple ring conductors, the grounding electrode is a ring grounding electrode, or the building's steel reinforcement or steel frame is used as the lightning protection device.

[0089] The lightning strike step voltage is calculated using two methods: a simplified calculation method and the Thapar calculation method.

[0090] Maximum step voltage calculation formula (simplified calculation method)

[0091]

[0092]

[0093]

[0094] The above is the calculation formula for a square grounding grid. If it is a rectangular grounding grid or other irregular grounding grid, the value of n is:

[0095]

[0096] L — Total length of the grounding grid (m)

[0097] Lj — Total length of the ground grid perimeter (m)

[0098] Thapar's formula for calculating the step voltage of irregular ground grids:

[0099]

[0100]

[0101]

[0102] Where ρ is the soil resistivity (Ω·m); I is the maximum current flowing through the grounding electrode (A); h is the burial depth of the grounding electrode (m); D is the spacing between parallel conductors (m); n is the number of parallel conductors in a single direction of the grounding grid; and L is the total length of the grounding grid (m).

[0103] In some embodiments, for irregular ground networks:

[0104] ,

[0105] Where Lj is the perimeter of the grounding grid (m); S is the area of ​​the grounding grid (m²). 2 Lx is the maximum length of the grounding grid along the x-direction (m); Ly is the maximum length of the grounding grid along the y-direction (m); Dm is the maximum diagonal length of the grounding grid (m).

[0106] Furthermore, the human body resistance is set to a corresponding impedance value based on the lightning current impact or the power frequency voltage safety design.

[0107] Furthermore, the step of establishing a three-dimensional simulation model of the grounding grid using electromagnetic field simulation software and performing frequency domain decomposition processing on the lightning current signal specifically includes:

[0108] The grounding grid modeling tool is used for modeling. The frequency domain calculation module is used to perform frequency domain decomposition of the lightning current time domain signal and step voltage frequency domain response calculation. Finally, the time domain conversion module is used to calculate the step voltage time domain response.

[0109] Furthermore, the lightning strike scenario is a large sports stadium, and the physical structural parameters include the total length of the grounding grid, the total length of the grounding grid perimeter, and the area of ​​the grounding grid.

[0110] Regarding the safety of pulsed currents, W.B. Kouwenhoven published two experimental studies in AIEE Trans. in 1958 and 1959, using dogs to conduct a series of experiments on the exponential discharge of charged capacitors. These experiments showed that reducing the time constant (shorter discharge time, narrower waveform) significantly improved the dog's ability to withstand voltage surges. Discharges with time constants less than 1µs to 3ms could prevent ventricular fibrillation at 40kV (the maximum peak surge current was 57A based on a dog's body resistance of 700Ω), while discharges with time constants of 17.5–35ms ​​caused ventricular fibrillation at 2.7–4kV (the maximum peak surge current was 3.9A to 5.7A based on a dog's body resistance of 700Ω).

[0111] According to Professor Xie Guangrun's book "Power System Grounding Technology", the impact current value (2.6 / 40µs) that can be fatal to humans due to the short duration of lightning strikes can reach 20 to 40A.

[0112] According to the book "On-site Electric Shock Rescue and Trauma First Aid" compiled by Jiangsu Electric Power Company, the harm of surge current to people is related to the energy of the surge discharge. A surge current of tens to hundreds of microseconds with an amplitude of tens of milliamperes or more can be felt, and an amplitude close to 100A may not necessarily cause ventricular fibrillation.

[0113] The IEEE Std80-2000 formula for the permissible current in the human body is based on animal experiments within the range of 0.03–3.0 s. Data from animal experiments at the microsecond level is currently scarce and remains a research topic. If we estimate the permissible lightning pulse current in the human body based on a 40 μs tail length for the 2.6 / 40 μs lightning current wave, the permissible lightning current for a 50 kg and 70 kg human body, determined by extrapolation from the IEEE formula, is 18.34 A and 24.82 A, respectively. This data is smaller than the impulse current value (2.6 / 40 µs) of 20–40 A described in Professor Jie Guangrun's "Power System Grounding Technology," and also smaller than the peak impulse current of 57 A in WB Kouwenhoven's animal experiments where the time constant was less than 1 µs to 3 ms and no ventricular fibrillation occurred. Therefore, based on the above data, the permissible lightning current value for the human body calculated using the IEEE formula is the smallest.

[0114] Secondly, the present invention provides a system for simulating and analyzing the step voltage gradient of a grounding grid in a lightning strike scenario, comprising:

[0115] The parameter acquisition module is used to acquire the lightning current parameters and the physical structure parameters of the grounding grid in the lightning strike scenario;

[0116] The model building module is used to construct models based on the lightning current parameters and the physical structure parameters, utilizing electromagnetic...

[0117] The simulation software establishes a three-dimensional simulation model of the grounding grid and performs frequency domain decomposition processing on the lightning current signal;

[0118] The voltage calculation module is used to calculate the step voltage of a lightning strike based on the simulation model using a step voltage calculation model.

[0119] The voltage is theoretically calculated to obtain step voltage distribution data;

[0120] The safety analysis module is used to combine human body impedance characteristics and safe current threshold, use frequency domain decomposition results to calculate step voltage time domain response, perform safety assessment analysis on the step voltage distribution data, and obtain the maximum step voltage that the human body can withstand.

[0121] Thirdly, the present invention also provides a computer-readable storage medium having a computer program stored thereon, characterized in that, when the program is executed by a processor, it implements the steps of the grounding grid step voltage gradient simulation analysis method in any of the lightning strike scenarios described in the present invention.

[0122] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0123] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes multiple instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing programs, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

Claims

1. A method for simulating and analyzing the step voltage gradient of a grounding grid in a lightning strike scenario, characterized in that, Includes the following steps: Obtain the lightning current parameters and the physical structure parameters of the grounding grid in the lightning strike scenario; Based on the lightning current parameters and the physical structure parameters, a three-dimensional simulation model of the grounding grid is established using electromagnetic field simulation software, and the lightning current signal is processed by frequency domain decomposition. Based on the simulation model, the step voltage calculation model is used to theoretically calculate the step voltage of lightning strikes and obtain the step voltage distribution data. By combining the human body impedance characteristics and safe current threshold, the step voltage time domain response is calculated using the frequency domain decomposition results. The safety assessment and analysis of the step voltage distribution data are then performed to obtain the maximum step voltage that the human body can withstand.

2. The method for simulating and analyzing the step voltage gradient of the grounding grid in a lightning strike scenario according to claim 1, characterized in that, The lightning current parameters include lightning current amplitude, wavefront time, and half-value time; the lightning current amplitude, wavefront time, and half-value time are set according to the standard lightning current waveform.

3. The method for simulating and analyzing the step voltage gradient of the grounding grid in a lightning strike scenario according to claim 1, characterized in that, The theoretical calculation of lightning strike step voltage using the step voltage calculation model specifically includes: For irregular grounding grids, the Thapar formula is used to obtain step voltage distribution data. In the Thapar formula, the step voltage is related to soil resistivity, maximum current flowing through the grounding electrode, maximum diagonal length of the grounding grid, conductor diameter, burial depth of the grounding electrode, spacing between parallel conductors, and number of parallel conductors in one direction of the grounding grid.

4. The method for simulating and analyzing the step voltage gradient of the grounding grid in a lightning strike scenario according to claim 1, characterized in that, The maximum step voltage that the human body can withstand is calculated using the following formula: When the building is surrounded by soil, the maximum step voltage that the human body can withstand is calculated using the following formula: Among them, R b Human body resistance, take R b = 1000Ω and 1500Ω, where ρ is the soil resistivity; When the building is surrounded by soil, the maximum step voltage that the human body can withstand is calculated using the following formula: ρ S The resistivity of the upper concrete layer is ρ when dry. S =2000Ω·m; ρ is the resistivity of the underlying soil in Ω·m; D is the thickness of the concrete.

5. The method for simulating and analyzing the step voltage gradient of the grounding grid in a lightning strike scenario according to claim 4, characterized in that, The safe current for the human body is set according to the weight of the human body, and different human body weights correspond to different safe current thresholds.

6. The method for simulating and analyzing the step voltage gradient of the grounding grid in a lightning strike scenario according to claim 4, characterized in that, The human body resistance is set to the corresponding impedance value according to the lightning current impact or the power frequency voltage safety design.

7. The method for simulating and analyzing the step voltage gradient of the grounding grid in a lightning strike scenario according to claim 1, characterized in that, The process of establishing a three-dimensional simulation model of the grounding grid using electromagnetic field simulation software and performing frequency domain decomposition processing on the lightning current signal specifically includes: The grounding grid modeling tool is used for modeling. The frequency domain calculation module is used to perform frequency domain decomposition of the lightning current time domain signal and step voltage frequency domain response calculation. Finally, the time domain conversion module is used to calculate the step voltage time domain response.

8. The method for simulating and analyzing the step voltage gradient of the grounding grid in a lightning strike scenario according to claim 1, characterized in that, The lightning strike scenario is a large sports stadium, and the physical structural parameters include the total length of the grounding grid, the total length of the grounding grid perimeter, and the area of ​​the grounding grid.

9. A system for simulating and analyzing the step voltage gradient of a grounding grid in a lightning strike scenario, characterized in that, include: The parameter acquisition module is used to acquire the lightning current parameters and the physical structure parameters of the grounding grid in the lightning strike scenario; The model building module is used to construct models based on the lightning current parameters and the physical structure parameters, utilizing electromagnetic... The simulation software establishes a three-dimensional simulation model of the grounding grid and performs frequency domain decomposition processing on the lightning current signal; The voltage calculation module is used to calculate the step voltage of a lightning strike based on the simulation model using a step voltage calculation model. The voltage is theoretically calculated to obtain step voltage distribution data; The safety analysis module is used to combine human body impedance characteristics and safe current threshold, use frequency domain decomposition results to calculate step voltage time domain response, perform safety assessment analysis on the step voltage distribution data, and obtain the maximum step voltage that the human body can withstand.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by the processor, the program implements the steps of the grounding grid step voltage gradient simulation analysis method as described in any one of claims 1 to 8.

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