Lightning ground lightning simulation method and system

Abstract

The invention discloses a lightning ground lightning simulation method, which includes the following steps: setting a lightning simulation grid, setting a grid lightning simulation parameter in the lightning simulation grid, setting the first developed discharge node of the main discharge channel in the lightning simulation grid; calculating the discharge probability, leader step length, and leader bifurcation angle between the first developed discharge node and its adjacent undeveloped discharge node according to the grid lightning simulation parameter; selecting a second developed discharge node from the discharge nodes to be developed according to the discharge probability, leader step length, and leader bifurcation angle between the first developed discharge node and its adjacent undeveloped discharge node, and selecting all other developed discharge nodes according to the selection method of the second developed discharge node, thereby forming a main discharge channel. The invention can establish a three-dimensional random model that has both physical properties and random properties and embodies the main macroscopic characteristics of lightning ground lightning.

Description

Technical Field

[0001] The present invention relates to the technical field of lightning protection, and in particular to a lightning ground-to-ground lightning simulation method and system. Background Art

[0002] The existing lightning simulation models cannot fully explain the phenomenon that the actual lightning tripping rate of transmission lines exceeds the simulation calculated value. Especially for transmission lines with high towers and large spans and lines located in complex terrain, there is an urgent need for a model that can more accurately simulate the lightning ground-to-ground flash discharge path, so as to more realistically reflect the characteristics of the curved and bifurcated development of the lightning ground-to-ground flash discharge path.

[0003] There are two main types of models for simulating lightning, one is the electrical geometry model (EGM) and the other is the leader development model (LPM). EGM only focuses on the final stage of lightning strikes and cannot simulate the lightning ground-to-ground discharge path; LPM is closer to the actual physical process of lightning strikes than EGM and has advantages in simulating lightning strikes on overhead transmission lines. However, most of the current versions of LPM assume that the downward leader channel develops perpendicular to the ground, which does not well reflect the structural characteristics of the curved and bifurcated lightning ground-to-ground discharge path.

[0004] In recent years, lightning observation and positioning technology has made great progress. It can achieve optical observation of lightning leader processes with a time resolution of hundreds of thousands of frames per second and three-dimensional high-precision positioning with an accuracy of less than tens of meters. This provides important technical support for further improving lightning ground-to-ground flash simulation. Summary of the invention

[0005] The purpose of the present invention is to provide a lightning-to-ground lightning simulation method and system, which can establish a three-dimensional random model that has both physical properties and random properties and embodies the main macroscopic characteristics of lightning-to-ground lightning.

[0006] To achieve this purpose, a lightning ground-to-ground lightning simulation method designed by the present invention comprises the following steps:

[0007] Setting a lightning simulation grid, setting grid lightning simulation parameters in the lightning simulation grid, and setting the first developed discharge node of the main discharge channel in the lightning simulation grid;

[0008] According to grid lightning simulation parameters, the discharge probability, leader step length, and leader bifurcation angle between the first developed discharge node and its adjacent undeveloped discharge node are calculated;

[0009] According to the discharge probability, leader step length and leader bifurcation angle between the first developed discharge node and its adjacent undeveloped discharge node, the second developed discharge node is selected from the discharge nodes to be developed, and all other developed discharge nodes are selected according to the selection method of the second developed discharge node, thereby forming a main discharge channel.

[0010] Randomly select a developed discharge node from all developed discharge nodes in the main discharge channel as the starting point of the branch channel;

[0011] According to the grid lightning simulation parameters, the discharge probability, leader step length and leader bifurcation angle between the starting point of the branch channel and its adjacent undeveloped discharge node are calculated;

[0012] According to the discharge probability, leader step length and leader bifurcation angle between the starting point of the branch channel and the adjacent undeveloped discharge node, the second developed discharge node of the branch channel is selected from the discharge nodes to be developed, and all other developed discharge nodes of the branch channel are selected according to the selection method of the second developed discharge node of the branch channel, thereby forming a branch discharge channel.

[0013] Beneficial effects of the present invention:

[0014] The present invention is based on the lightning leader bifurcation angle and leader step length parameters obtained by analyzing the measured lightning three-dimensional positioning data. Since the lightning leader bifurcation angle and step length parameters obtained from the measured data analysis are incorporated, the macroscopic characteristics of natural lightning strikes can be reflected, and an engineering applicable model that reflects the real macroscopic characteristics of natural lightning strikes can be established. The authenticity of lightning strike simulation for ground targets such as transmission lines can be further improved, thereby improving the analysis level. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the steps of the lightning to ground flash simulation method;

[0016] Figure 2 It is a schematic diagram of the smallest unit of three-dimensional simulation space;

[0017] Figure 3 This is a schematic diagram of a lightning to ground flash simulation system;

[0018] Figure 4 This is the lightning discharge channel simulation result example 1;

[0019] Figure 5 This is the lightning discharge channel simulation result example 2;

[0020] Figure 6 This is Example 3 of the lightning discharge channel simulation results. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0022] Embodiment 1:

[0023] like Figure 1 A lightning ground lightning simulation method is shown, which comprises the following steps:

[0024] Setting a lightning simulation grid, setting grid lightning simulation parameters in the lightning simulation grid, and setting the first developed discharge node of the main discharge channel in the lightning simulation grid;

[0025] According to grid lightning simulation parameters, the discharge probability, leader step length, and leader bifurcation angle between the first developed discharge node and its adjacent undeveloped discharge node are calculated;

[0026] According to the discharge probability, leader step length and leader bifurcation angle between the first developed discharge node and its adjacent undeveloped discharge node, the second developed discharge node is selected from the discharge nodes to be developed, and all other developed discharge nodes are selected according to the selection method of the second developed discharge node, thereby forming a main discharge channel.

[0027] A lightning ground lightning simulation method further includes: randomly selecting a developed discharge node from all developed discharge nodes in a main discharge channel as a starting point of a branch channel;

[0028] According to the grid lightning simulation parameters, the discharge probability, leader step length and leader bifurcation angle between the starting point of the branch channel and its adjacent undeveloped discharge node are calculated;

[0029] According to the discharge probability, leader step length and leader bifurcation angle between the starting point of the branch channel and the adjacent undeveloped discharge node, the second developed discharge node of the branch channel is selected among the discharge nodes to be developed, and all other developed discharge nodes of the branch channel are selected according to the selection method of the second developed discharge node of the branch channel, thereby forming a branch discharge channel; compared with the leader development model currently widely used in the engineering field, this scheme can simulate lightning to ground flashes more realistically by simulating branch channels.

[0030] The specific method of setting the lightning simulation grid, setting the grid lightning simulation parameters in the lightning simulation grid, and setting the first developed discharge node of the main discharge channel in the lightning simulation grid is:

[0031] The lightning simulation grid is set to initialize the lightning simulation grid, and the range and grid spacing in the three directions of X, Y, and Z are set to gridSpacing, where X and Y represent the length and width of the lightning simulation grid, ranging from 0 to 10 km, and Z represents the height of the thundercloud, ranging from 4 to 8 km, and the gridSpacing setting range is 0.01 to 0.2 km; the lightning simulation grid is a three-dimensional space of X×Y×Z, and the number of grid points in the entire lightning simulation grid is The thundercloud height is set to Z, x1, y1, z1 represent the first coordinates of the X-axis, Y-axis and Z-axis respectively, end ,y end ,z endRespectively represent the last coordinate of the X-axis, Y-axis and Z-axis; end-1 ,y end-1 ,z end-1 They represent the penultimate coordinates of the X-axis, Y-axis and Z-axis respectively; in the present invention, X=10km; Y=10km; Z=4km is set, and the grid spacing is gridSpacing=0.1km, which means that the lightning simulation grid is a three-dimensional space of 10km×10km×4km, the thundercloud height is set at 4km, and the number of grid points in the entire simulation space is 100×100×40.

[0032] Setting the grid lightning simulation parameters includes setting the critical electric field strength, the average electric field strength of the pilot channel, the peak current, the convergence tolerance, the propagation parameters, the branch length, and the number of branches reaching the ground;

[0033] According to the electric field strength required for the stable development of the negative polarity leader, the critical electric field strength E is preset. cr , range 5×10 5 ~1.0×10 6 V / m, E in the present invention cr =1.0×10 6 V / m, critical electric field strength E cr Used to calculate the discharge probability P(AA') of a developed discharge node to an adjacent undeveloped discharge node i ), A is the developed discharge node, A' i is the adjacent undeveloped discharge node, such as Figure 2 As shown, i = 1, 2, 3 ... n, the value range of n is 1 to 26, that is, 26 undeveloped discharge nodes around the developed node;

[0034] Since the lightning leader channel carries charge, this part of the charge causes the electric potential to change. According to the observation results of natural lightning, the average electric field strength E of the leader channel per unit length is preset. ch , range 0~1.0×10 4 V / m, E in the present invention ch =1.0×10 4 V / m, used to calculate the potential V of all grid points in the lightning simulation grid k (x j ,y j ,z j ), k = 0, 1, 2…N, N means the whole simulation process needs N iterations in total, (x j ,y j ,z j ) represents the grid point coordinates in the lightning simulation grid, x j ,y j ,z jRepresents any coordinate of the X-axis, Y-axis and Z-axis respectively;

[0035] The peak current I is preset in the range of -10kA to -200kA for calculating the initial cloud potential V0(x j ,y j ,z j );

[0036] During the simulation process, the potential of all grid points needs to be updated at each step. When the difference between the potential of all grid points after the update and the potential of all grid points before the update is less than a certain threshold, it is considered that the potential distribution tends to be stable and the simulation is difficult to continue. The threshold is the convergence tolerance, which is preset. In the present invention, the Tolerance is set to 1.0×10 -4 V, used to determine the cessation of discharge channel development;

[0037] The propagation parameter η is preset, and the value range of η is 2 to 8, which is used to control the number of discharge branches and calculate the discharge probability P(AA′) from the developed discharge node to the adjacent undeveloped discharge node. i );

[0038] According to the natural lightning observation results, the branch length is preset, and the branch length value range is 3 to 12 steps. In the present invention, it is set to 12 steps to control the upper limit of the branch length;

[0039] According to the natural lightning observation results, the number of branches reaching the ground is preset, and the number of branches ranges from 1 to 5, which is used to control the number of branches reaching the ground. In the present invention, it is set to 5;

[0040] Set the top center of the simulation space as the first developed discharge node of the main discharge channel, that is, point (xe nd / 2 ,y end / 2 、z end ) is the first developed discharge node of the main discharge channel, and in the present invention, (x 50 ,y 50 、z 40 ).

[0041] A lightning ground lightning simulation method, which also includes: a specific method for calculating the discharge probability, leader step length, and leader bifurcation angle between the first developed discharge node and its adjacent undeveloped discharge node according to grid lightning simulation parameters is:

[0042] Set the relationship between peak current and thundercloud potential, and calculate the initial cloud potential by formula (1);

[0043] V0=3.6858+0.7282×I-0.000818×I 2(1)Where: V0 represents the initial cloud potential, I represents the peak current;

[0044] Assuming that the cloud potential decreases linearly with height, the initial potential of all grid points in the lightning simulation grid is calculated using formula (2);

[0045]

[0046] z j Represents the coordinates of the grid point on the Z axis;

[0047] According to the initial potential of all grid points in the lightning simulation grid, the electric field intensity between the developed discharge node and the adjacent undeveloped discharge node is calculated by formula (3):

[0048]

[0049] Where: (x m ,y m ,z m ) is the grid coordinate of the developed discharge node A, A' i is the adjacent undeveloped discharge node, gardX, gardY, gardZ are the developed discharge node A and the adjacent undeveloped discharge node A' i The intermediate amount of potential difference between them in the X, Y, and Z directions;

[0050] According to the electric field strength E(AA' between the developed discharge node and the adjacent undeveloped discharge node i ), propagation parameter η and critical electric field strength E cr , when the electric field strength between the developed discharge node and the adjacent undeveloped discharge node is less than the critical electric field strength E cr When the discharge probability P(AA') between the developed discharge node and the adjacent undeveloped discharge node is determined by formula (4) i ) is 0; when the electric field strength between the developed discharge node and the adjacent undeveloped discharge node is greater than the critical electric field strength E cr When , the discharge probability P(AA') between the developed discharge node and the adjacent undeveloped discharge node is calculated by formula (5) i )

[0051]

[0052] According to lightning observation data, the length of the leading step s is distributed between 10m and 200m. A truncated normal distribution is designed, as shown in formula (6):

[0053] s~TruncNormal(μ,σ,a,b) (6)

[0054] μ is the mean of the distribution;

[0055] σ is the standard deviation of the distribution;

[0056] a and b are the lower and upper limits of the distribution, and their values ​​in standard normal distribution units are and

[0057] According to the lightning observation data, the Beta step is selected and the leading bifurcation angle is calculated by formula (7):

[0058] Angle=Beta(α,β)×60° (7)

[0059] In the formula, Angle is the bifurcation angle between the previous discharge channel and the next adjacent discharge channel, α and β are both positive integers. In the present invention, α=2, β=5, and 0° represents the same direction as the negative direction of the z-axis.

[0060] A lightning ground lightning simulation method, which also includes, according to the discharge probability, leader step length, and leader bifurcation angle between the first developed discharge node and its adjacent undeveloped discharge node, a specific method of selecting a second developed discharge node from the discharge nodes to be developed is:

[0061] After obtaining the discharge probability, leading step length, and leading bifurcation angle between the developed discharge node and its adjacent undeveloped discharge node, select the undeveloped discharge node A whose discharge probability is greater than 0, whose leading step length satisfies formula (6), and whose leading bifurcation angle satisfies formula (7). i , if there are multiple undeveloped discharge nodes A that meet the requirements i , select the undeveloped discharge node A with the largest discharge probability with the developed discharge node A i is the next discharge node. If none of the nodes meets the requirements, the node directly below the discharge node is selected as the next discharge node.

[0062] A lightning ground lightning simulation method, which also includes: updating the potential of each grid point in the lightning simulation grid according to formula (8) based on the developed discharge node selected from the discharge nodes to be developed;

[0063] V k+1 (x j ,y j ,z j )=V k (x j ,y j ,z j )-s×E ch (8)

[0064] Where: s represents the leading step length, E ch Represents the average electric field strength per unit length of the pilot channel, Vk (x j ,y j ,z j ) represents the potential of all grid points in the lightning simulation grid, V k+1 (x j ,y j ,z j ) represents the potential of all grid points in the lightning simulation grid after each step of the leader channel update;

[0065] A lightning ground-to-ground lightning simulation method, which also includes boundary condition application;

[0066] The boundary conditions include Dirichlet boundary conditions and Neumann boundary conditions, which are used to process the boundary of the simulation domain to prevent abnormalities such as low calculation efficiency and inaccurate calculation results from occurring at the boundary;

[0067] For the Dirichlet boundary condition, the potentials of all nodes on the boundary of the lightning simulation grid are set to 0, as shown in formula (9):

[0068]

[0069] For the Neumann boundary condition, the potential gradients of the nodes on the boundary of the lightning simulation grid are all set to 0, as shown in formula (10):

[0070]

[0071] A lightning ground lightning simulation method also includes controlling the growth of branch discharge channels. The specific method of controlling the growth of branch discharge channels is: avoiding the branch discharge channels from crossing the main discharge channels or other branch discharge channels, that is, forcing the discharge nodes of the branch discharge channels to not be developed discharge nodes. And according to the preset number of branches reaching the ground, the number of branches that develop to the ground is limited.

[0072] A lightning ground lightning simulation method, which also includes a discharge channel stop updating judgment;

[0073] The conditions for judging whether the main discharge channel stops developing include: Condition 1: whether the main discharge channel touches the simulation boundary; Condition 2: whether the potential difference before and after the grid point update is less than the convergence tolerance of the potential network, that is, max(|V k+1 (x j ,y j ,z j )-V k (x j ,y j ,z j)|)<Tolerance; If the main discharge channel touches the simulation boundary or the potential difference before and after the grid point update is less than the convergence tolerance of the potential network, the main discharge channel stops updating;

[0074] For the condition to judge whether the development of the branch discharge channel stops, it includes: Condition 1: Whether the branch discharge channel touches the simulation boundary; Condition 2: Whether the branch discharge channel reaches the upper limit of the allowed branch length; Condition 3: Whether the potential difference before and after the grid point update is less than the convergence tolerance of the potential network, that is, max(|V k+1 (x j ,y j ,z j ) - V k (x j ,y j ,z j )|)<Tolerance; If the branch discharge channel touches the simulation boundary and / or the branch discharge channel reaches the upper limit of the allowed branch length and / or the potential difference before and after the sub-grid point update is less than the convergence tolerance of the potential network, the main discharge channel stops updating.

[0075] A lightning ground flash simulation method further includes storing the discharge nodes of the main discharge channel and the branch discharge channel. The discharge nodes of the main discharge channel and the branch channel are stored separately in different positions. When storing the discharge nodes, they need to be stored in the order of development for subsequent visualization and analysis of the discharge channel.

[0076] The simulation result of the lightning discharge channel is as Figures 4 to 6 shown.

[0077] Embodiment 2:

[0078] A lightning ground flash simulation system, as Figure 3 shown, it includes a user interaction interface module and a simulation engine module;

[0079] The user interaction interface module is used to set the lightning simulation grid, set the grid lightning simulation parameters in the lightning simulation grid, and set the first developed discharge node of the main discharge channel in the lightning simulation grid;

[0080] The simulation engine module is used to calculate the discharge probability, leader step length, and leader bifurcation angle between the first developed discharge node and its adjacent undeveloped discharge nodes according to the grid lightning simulation parameters;

[0081] And according to the discharge probability, leader step length, and leader bifurcation angle between the first developed discharge node and its adjacent undeveloped discharge nodes, select the second developed discharge node among the discharge nodes to be developed, and select all other developed discharge nodes according to the selection method of the second developed discharge node, thereby forming the main discharge channel.

[0082] The simulation engine module is also used to randomly select a developed discharge node from all developed discharge nodes in the main discharge channel as the starting point of the branch channel;

[0083] And according to the grid lightning simulation parameters, the discharge probability, leader step length and leader bifurcation angle between the starting point of the branch channel and its adjacent undeveloped discharge node are calculated;

[0084] According to the discharge probability, leader step length and leader bifurcation angle between the starting point of the branch channel and the adjacent undeveloped discharge node, the second developed discharge node of the branch channel is selected from the discharge nodes to be developed, and all other developed discharge nodes of the branch channel are selected according to the selection method of the second developed discharge node of the branch channel, thereby forming a branch discharge channel.

[0085] A lightning ground-to-ground lightning simulation system, which also includes a simulation parameter sending module, a visualization display module and a simulation data post-analysis module;

[0086] The simulation requirement sending module is used to receive simulation requirements and simulation parameters from the user interaction interface and send them to the simulation engine module;

[0087] The visualization module is used to convert the data generated by the simulation engine into graphs or charts to provide intuitive visual representation. It can display the dynamic simulation of the lightning-to-ground flash process, or generate statistical analysis charts of the simulation results;

[0088] The simulation data post-analysis module is used to conduct in-depth analysis of the data output by the simulation engine. It can calculate and evaluate various parameters, such as the transmission line trip rate.

[0089] Embodiment 3:

[0090] A computer-readable storage medium stores a computer program, which implements the steps of the above method when executed by a processor.

[0091] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A lightning ground lightning simulation method, characterized in that: It includes the following steps: Setting a lightning simulation grid, setting grid lightning simulation parameters in the lightning simulation grid, and setting the first developed discharge node of the main discharge channel in the lightning simulation grid; According to grid lightning simulation parameters, the discharge probability, leader step length, and leader bifurcation angle between the first developed discharge node and its adjacent undeveloped discharge node are calculated; According to the discharge probability, the leader step length and the leader bifurcation angle between the first developed discharge node and its adjacent undeveloped discharge node, a second developed discharge node is selected from the discharge nodes to be developed, and all other developed discharge nodes are selected according to the selection method of the second developed discharge node, so as to form a main discharge channel; According to lightning observation data, a truncated normal distribution is designed, as shown in formula (6): s~TruncNormal(μ,σ,a,b) (6) μ is the mean of the distribution; σ is the standard deviation of the distribution; a and b are the lower and upper limits of the distribution, and s is the leading step size; The beta step is selected according to the lightning observation data, and the leading bifurcation angle is calculated by formula (7); Angle=Beta(α,β)×60° (7) Where Angle is the bifurcation angle between the previous discharge channel and the next adjacent discharge channel, and α and β are both positive integers.

2. The lightning ground lightning simulation method according to claim 1, characterized in that: Randomly select a developed discharge node from all developed discharge nodes in the main discharge channel as the starting point of the branch channel; According to the grid lightning simulation parameters, the discharge probability, leader step length and leader bifurcation angle between the starting point of the branch channel and its adjacent undeveloped discharge node are calculated; According to the discharge probability, leader step length and leader bifurcation angle between the starting point of the branch channel and the adjacent undeveloped discharge node, the second developed discharge node of the branch channel is selected from the discharge nodes to be developed, and all other developed discharge nodes of the branch channel are selected according to the selection method of the second developed discharge node of the branch channel, thereby forming a branch discharge channel.

3. The lightning ground lightning simulation method according to claim 1, characterized in that: The specific method of setting the lightning simulation grid, setting the grid lightning simulation parameters in the lightning simulation grid, and setting the first developed discharge node of the main discharge channel in the lightning simulation grid is as follows: Set the lightning simulation grid to initialize the lightning simulation grid, set the grid spacing in the X, Y, and Z directions to gridSpacing, where X and Y represent the length and width of the lightning simulation grid, and Z represents the height of the thundercloud. The lightning simulation grid is a three-dimensional space of X×Y×Z, and the number of grid points in the entire lightning simulation grid is The height of the thundercloud is set to Z, x1, y1, z1 represent the first coordinates of the X-axis, Y-axis and Z-axis respectively, end ,y end , z end Represents the last coordinate of the X-axis, Y-axis, and Z-axis respectively, x end-1 ,y end-1 , z end-1 Represents the penultimate coordinates of the X-axis, Y-axis, and Z-axis respectively; Setting the grid lightning simulation parameters includes setting the critical electric field strength, the average electric field strength of the pilot channel, the peak current, the convergence tolerance, the propagation parameters, the branch length, and the number of branches reaching the ground; According to the electric field strength required for the stable development of the negative polarity leader, the critical electric field strength E is preset. cr , critical electric field strength E cr It is used to calculate the discharge probability P(AA′) of a developed discharge node to an adjacent undeveloped discharge node. i ), A is the developed discharge node, A′ i is the adjacent undeveloped discharge node, i=1, 2, 3…n; According to the observation results of natural lightning, the average electric field strength E of the pilot channel per unit length is preset. ch , average electric field strength E ch Used to calculate the potential V of all grid points in the lightning simulation grid k (x j ,y j , z j ), k = 0, 1, 2...N, N means the whole simulation process needs N iterations in total, (x j ,y j , z j ) represents the grid point coordinates in the lightning simulation grid, x j ,y j , z j Represents any coordinate of the X-axis, Y-axis and Z-axis respectively; The peak current I is preset and used to calculate the initial cloud potential V0(x j ,y j , z j ); The convergence tolerance Tolerance is preset, and the convergence tolerance Tolerance is used as a threshold to determine whether the discharge channel development stops; The propagation parameter η is preset, and the propagation parameter η is used to control the number of discharge branches and calculate the discharge probability P(AA′) from the developed discharge node to the adjacent undeveloped discharge node. i ) According to the natural lightning observation results, the branch length is preset, and the branch length is used to control the upper limit of the branch length; According to the natural lightning observation results, the number of branches reaching the ground is preset, and the number of branches is used to control the number of branches that develop and reach the ground; Set the top center of the simulation space as the first developed discharge node of the main discharge channel, that is, point (x end / 2 ,y end / 2 、z end ) is the first developed discharge node of the main discharge channel.

4. The lightning ground lightning simulation method according to claim 1, characterized in that: The specific method for calculating the discharge probability, leader step length, and leader bifurcation angle between the first developed discharge node and its adjacent undeveloped discharge node according to grid lightning simulation parameters is as follows; Assuming that there is a relationship between the peak current and the thundercloud potential, the initial cloud potential is calculated by formula (1); V0=3.6858+0.7282×I-0.000818×I 2 (1) Where: V0 represents the initial cloud potential, I represents the peak current; Assuming that the cloud potential decreases linearly with height, the initial potential of any grid point in the lightning simulation grid is calculated using formula (2); z j Represents the coordinates of the grid point on the Z axis; According to the initial potential of any grid point in the lightning simulation grid, the electric field strength between the developed discharge node and the adjacent undeveloped discharge node is calculated by formula (3): Where: (X m ,y m , z m ) is the grid coordinate of the developed discharge node A, gradX, gradY, gradZ are the intermediate values ​​of the potential difference between the developed discharge node A and the adjacent undeveloped discharge node A′i in the X, Y, and Z directions; According to the electric field strength E(AA′ between the developed discharge node and the adjacent undeveloped discharge node i ), propagation parameter η and critical electric field strength E cr , when the electric field strength between the developed discharge node and the adjacent undeveloped discharge node is less than the critical electric field strength E cr When the discharge probability P(AA′j) between the developed discharge node and the adjacent undeveloped discharge node is determined to be 0 by formula (4); when the electric field strength between the developed discharge node and the adjacent undeveloped discharge node is greater than or equal to the critical electric field strength E cr When , the discharge probability P(AA′) between the developed discharge node and the adjacent undeveloped discharge node is calculated by formula (5) i ) P(AA′ i )=0,if|E(AA′ i )|<E cr (4) The length of the leading step s ranges from 10m to 200m.

5. The lightning ground lightning simulation method according to claim 4, characterized in that: According to the discharge probability, leader step length, and leader bifurcation angle between the first developed discharge node and its adjacent undeveloped discharge node, the specific method for selecting the second developed discharge node from the discharge nodes to be developed is as follows: After obtaining the discharge probability, leading step length, and leading bifurcation angle between the developed discharge node and its adjacent undeveloped discharge node, select the undeveloped discharge node Ai that satisfies the conditions that the discharge probability is greater than 0, the leading step length satisfies formula (6), and the leading bifurcation angle satisfies formula (7). If there are multiple undeveloped discharge nodes Ai that meet the requirements, select the undeveloped discharge node Ai with the largest discharge probability with the developed discharge node A as the next discharge node. If no requirements are met, select the node directly below the discharge node as the next discharge node.

6. The lightning ground lightning simulation method according to claim 1, characterized in that: It also includes, according to the developed discharge node selected from the discharge nodes to be developed, updating the potential of each grid point in the lightning simulation grid according to formula (8); V k+1 (x j ,y j ,z j )=V k (x j ,y j ,z j )-s×E ch (8) Where: s represents the leading step length, E ch Represents the average electric field strength per unit length of the pilot channel, V k (x j ,y j , z j ) represents the potential of any grid point in the lightning simulation grid, V k+1 (x j ,y j , z j ) represents the electric potential of any grid point in the lightning simulation grid after each step of the leader channel update.

7. The lightning ground lightning simulation method according to claim 3, characterized in that: It also includes boundary condition application; The boundary conditions include Dirichlet boundary conditions and Neumann boundary conditions, which are used to process the boundary of the simulation domain to prevent abnormalities such as low calculation efficiency and inaccurate calculation results from occurring at the boundary; For the Dirichlet boundary condition, the potentials of all nodes on the boundary of the lightning simulation grid are set to 0, as shown in formula (9): For the Neumann boundary condition, the potential gradients of the nodes on the boundary of the lightning simulation grid are all set to 0, as shown in formula (10):

8. A lightning ground lightning simulation system based on the method of claim 1, characterized in that: It includes a user interaction interface module and a simulation engine module; The user interaction interface module is used to set the lightning simulation grid, set the grid lightning simulation parameters in the lightning simulation grid, and set the first developed discharge node of the main discharge channel in the lightning simulation grid; The simulation engine module is used to calculate the discharge probability, leader step length, and leader bifurcation angle between the first developed discharge node and its adjacent undeveloped discharge node according to grid lightning simulation parameters; And according to the discharge probability, leader step length and leader bifurcation angle between the first developed discharge node and its adjacent undeveloped discharge node, the second developed discharge node is selected from the discharge nodes to be developed, and all other developed discharge nodes are selected according to the selection method of the second developed discharge node, thereby forming a main discharge channel.

9. The lightning ground lightning simulation system according to claim 8, characterized in that: The simulation engine module is used to randomly select a developed discharge node from all developed discharge nodes in the main discharge channel as the starting point of the branch channel; And according to the grid lightning simulation parameters, the discharge probability, leader step length and leader bifurcation angle between the starting point of the branch channel and its adjacent undeveloped discharge node are calculated; According to the discharge probability, leader step length and leader bifurcation angle between the starting point of the branch channel and the adjacent undeveloped discharge node, the second developed discharge node of the branch channel is selected from the discharge nodes to be developed, and all other developed discharge nodes of the branch channel are selected according to the selection method of the second developed discharge node of the branch channel, thereby forming a branch discharge channel.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method according to claim 1 are implemented.

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