Lightning stroke risk assessment system and method for power transmission line, and storage medium

Abstract

The invention discloses a power transmission line lightning stroke risk assessment system and method and a storage medium, and the method comprises the steps: dividing a mountain and a flat ground region around the mountain into a plurality of extraction sections, and dividing the boundary of a mesoscopic terrain according to the cloud-to-ground lightning density variation coefficient of the extraction sections and the average cloud-to-ground lightning density variation coefficient of the flat ground region, dividing the range from the boundary of the mesoscopic terrain to the peak of the mountain into mesoscale terrains; according to the space electric field of the meso-scale terrain, establishing a meso-terrain lightning downlink pilot fractal development model, and carrying out simulation calculation on the model to obtain meso-terrain ground thunderbolt distribution; the mesoscopic terrain ground thunderbolt distribution serves as the ground lightning density of each area of the complex terrain, the power transmission line lightning trip-out rate of each area of the complex terrain is calculated according to the ground lightning density and the thunder observation data, and the lightning risk of each area of the complex terrain is evaluated through the power transmission line lightning trip-out rate. According to the invention, power transmission line lightning stroke risk assessment in a complex terrain region is realized in a more refined manner.

Description

Technical Field

[0001] The present invention relates to the technical field of transmission line lightning strike risk assessment, and specifically to a transmission line lightning strike risk assessment system and method and a storage medium, and in particular to a transmission line lightning strike risk assessment system and method and a storage medium integrating mesoscopic-scale terrain. Background Art

[0002] Lightning has become a serious threat to the safe operation of transmission lines. The assessment of lightning strike risk of transmission lines is an important task in the operation and maintenance of power systems. At present, the traditional lightning strike risk assessment method is mainly based on the statistical data of thunderstorm activity in the region under the macro terrain. However, the application effect of this method in complex terrain areas is not ideal, because the transmission lines span a large area and the terrain changes a lot. For the same area, different terrains will have an important impact on the results of lightning strike risk assessment. The existing technology has not completely solved the problem of accurately assessing the lightning strike risk of transmission lines in complex terrain areas. Therefore, a new method is needed to more accurately assess the lightning strike risk of transmission lines in complex terrain areas.

[0003] The prior art discloses "a transmission line risk assessment method", which comprehensively considers the equipment risk value based on status evaluation, the transmission line overload risk value and the static voltage over-limit risk value, and assigns corresponding dynamic weight values ​​to each risk value, and obtains the comprehensive risk value of the transmission line. However, there is no corresponding assessment method for lightning strike risk, which cannot meet the overall risk assessment needs of transmission lines.

[0004] The prior art discloses "a method and related equipment for assessing lightning strike risk of power transmission lines". This method proposes lightning density in the buffer area drawn based on lightning data, synchronously compares historical tripping data with historical lightning density, and then performs lightning risk classification based on lightning strike distance, lightning strike density, historical lightning strike density and real-time meteorological data to obtain the lightning strike risk of power transmission lines. However, this method still cannot assess the lightning strike risk in complex terrain areas. Summary of the invention

[0005] The purpose of the present invention is to address the defect that the prior art cannot evaluate the lightning risk in complex terrain areas. Therefore, it is necessary to further process the macro terrain and propose a lightning risk assessment method that can integrate the meso terrain, so as to achieve a more refined lightning risk assessment for transmission lines in complex terrain areas, thereby proposing a transmission line lightning risk assessment system and method and storage medium. The system first divides the complex terrain area into mesoscale, and establishes a lightning downlead fractal development model based on the divided mesoscale terrain, and then simulates and calculates the lightning downlead fractal development model to obtain the ground lightning density in each area of ​​the mesoscale terrain, and finally calculates the lightning trip rate of the transmission line in the complex terrain area through the ground lightning density in each area of ​​the mesoscale terrain and the lightning observation data, thereby evaluating the lightning risk. The present invention proposes the distribution of ground lightning in the mesoscale terrain between the macro terrain and the micro terrain, so as to achieve a more refined lightning risk assessment for the transmission line in the complex terrain area, and provides technical support for the lightning risk assessment of the complex terrain transmission line.

[0006] To achieve this object, the first aspect of the present invention provides a transmission line lightning strike risk assessment system, comprising: a terrain scale division module, used to divide the mountain and the flat area outside the critical area of ​​the mountain into a plurality of extraction sections, divide the boundary of the mesoscopic terrain according to the ground lightning density variation coefficient of the extraction section and the average ground lightning density variation coefficient of the flat area, and divide the range from the boundary of the mesoscopic terrain to the top of the mountain into the mesoscopic scale terrain;

[0007] A ground lightning distribution module is used to establish a mesoscopic terrain lightning downward leader fractal development model according to the spatial electric field of the mesoscopic terrain, and obtain the mesoscopic terrain ground lightning distribution by simulating and calculating the mesoscopic terrain lightning downward leader fractal development model;

[0008] The lightning risk assessment module is used to use the ground lightning distribution of the mesoscopic terrain as the ground lightning density of each area of ​​the terrain to be assessed, calculate the lightning tripping rate of the transmission line in each area of ​​the terrain to be assessed according to the ground lightning density and lightning observation data of each area of ​​the terrain to be assessed, and assess the lightning risk of each area of ​​the terrain to be assessed through the transmission line lightning tripping rate.

[0009] Furthermore, a specific method for dividing the mountain and the flat area outside the critical area of ​​the mountain into several extraction segments is: using the three-dimensional space formed by the width of the mountain, the height of the mountain, and the flat area from the mountain to the critical area of ​​the mountain as the research space for mesoscopic terrain scale division, and dividing the research space along the extraction direction from the flat area to the mountain area into several extraction segments with the same distance in the extraction direction.

[0010] Furthermore, the specific method for dividing the boundary of the mesoscopic terrain according to the ground-to-ground lightning density variation coefficient of the extracted section and the average ground-to-ground lightning density variation coefficient of the flat area is: respectively calculate the ground-to-ground lightning density variation coefficients of several of the extracted sections, and compare the ground-to-ground lightning density variation coefficients of the several extracted sections obtained with the average ground-to-ground lightning density variation coefficient of the flat area in the study space; if the ground-to-ground lightning density variation coefficient of the extracted section is greater than the ground-to-ground lightning density variation coefficient of the flat area, then the extracted section is the critical section of the mesoscopic terrain scale in the study space, and the midpoint of the critical section is taken as the boundary of the mesoscopic terrain.

[0011] Furthermore, a specific method for establishing a mesoscopic terrain lightning downward leader fractal development model based on the spatial electric field of the mesoscopic terrain is as follows: the mesoscopic terrain is divided into a grid with discrete grid points of equal spacing, and the potential relationship of the spatial electric field formed by each discrete grid point in the grid is shown in the following formula:

[0012]

[0013] In the formula, is the potential of the grid point at the i-th row and j-th column in the grid, is the potential of the grid point at the i+1th row and jth column in the grid, is the potential of the grid point at the i-th row and j+1-th column in the grid, is the potential of the grid point at the i-th row and j-1-th column in the grid, is the potential of the grid point at the i-1th row and jth column in the grid;

[0014] Formula (1) is calculated using the super-relaxation iteration method, and the potential relationship of the spatial electric field of the grid after iteration is shown as follows:

[0015]

[0016] In the formula, After the nth iteration The value of ω is the relaxation factor, After the n+1th iteration The value of After the n+1th iteration The value of After the n+1th iteration The value of After the n+1th iteration The value of After the n+1th iteration The value of

[0017] The calculation formula of the optimal relaxation factor that makes the iterative process converge fastest in formula (2) is as follows:

[0018]

[0019] Where ω0 is the optimal relaxation factor, n and m are the number of grids divided by the length and width of the mesoscopic terrain in the rectangular area, respectively;

[0020] The potential development point of the lightning downward leader is determined according to the discharge grid points inside the lightning discharge channel in the mesoscopic terrain. The determination formula is as follows:

[0021]

[0022] Where E is the average field strength between the discharge grid point inside the lightning discharge channel and the potential development point of the lightning leader. is the potential difference between the discharge grid point inside the lightning discharge channel and the potential development point of the downward leader of the lightning, L is the actual distance between the discharge grid point inside the lightning discharge channel and the potential development point of the downward leader of the lightning, E c is the critical discharge field strength, E c =216kV / m;

[0023] The probability of the development of the potential development point of the downward leader of lightning is as follows:

[0024]

[0025] In the formula, The discharge grid point N inside the lightning discharge channel develops to the potential development point N of the lightning downward leader * The probability of The distance from the discharge grid point N inside the lightning discharge channel to the potential development point N of the lightning downward leader * The electric field strength between them, η is the development probability index, E c is the critical discharge field strength, E c =216kV / m;

[0026] The potential development point of the downward leader of lightning develops into a discharge grid point inside a new lightning discharge channel. The potential calculation formula of the potential development point of the downward leader of lightning is as follows:

[0027]

[0028] In the formula, The potential development point N of the lightning leader that develops into a new lightning discharge channel * The potential, is the potential of the discharge grid point N inside the lightning discharge channel, E ch is the electric field strength inside the new lightning discharge channel, From the discharge grid point N to the potential development point N * The distance between.

[0029] Furthermore, the mesoscopic terrain lightning downward leader fractal development model is simulated and calculated to obtain the specific method of the ground lightning distribution in the mesoscopic terrain: the potential and electric field strength of each grid point in the mesoscopic terrain are calculated, and the position and potential of the potential development point of the lightning downward leader are continuously calculated through the mesoscopic terrain lightning downward leader fractal development model. When the potential development point of the lightning downward leader undergoes a jump change, the simulation of a lightning strike process is completed, and the above process is repeated until the simulation of t lightning strike processes is completed, and the coordinates of all lightning strike points are recorded to obtain the ground lightning distribution in the mesoscopic terrain.

[0030] Furthermore, the specific method for calculating the lightning trip rate of the transmission line in each area of ​​the terrain to be evaluated according to the ground lightning density and lightning observation data in each area of ​​the terrain to be evaluated is as follows: the calculation formula for the strike-back trip rate is obtained according to the ground lightning density and lightning observation data in each area of ​​the terrain to be evaluated:

[0031] P f =N×g×P I ×η (7)

[0032]

[0033] Where P f is the strike tripping rate, N is the total number of annual lightning strikes in the divided mesoscopic terrain, g is the pole striking rate, which is 1 / 6 in plains and 1 / 4 in mountainous areas, and P I is the probability of a lightning current greater than I, η is the arcing rate, η = 0.4, Ng is the density of ground lightning in each area of ​​the terrain to be evaluated, b is the distance between the two lightning conductors, and h is the height of the lightning conductor above the ground;

[0034] The calculation formula for the shielding failure trip rate is obtained based on the lightning density and lightning observation data in each area of ​​the terrain to be evaluated as follows:

[0035]

[0036] f(I)=I max (0.1r max ) 1.54 (10)

[0037] Where P r is the interruption tripping rate, η is the arcing rate, η=0.4, ΔL is the collector line section with a length of ΔL, N g is the density of ground-to-ground lightning in each area of ​​the terrain to be evaluated, I max is the maximum current amplitude of the shielding flashover, I C is the lightning current amplitude, l BDis the lightning strike exposure width, f(I) is the lightning current probability density function, and r max is the maximum shielding failure striking distance;

[0038] According to the cloud-to-ground flash density and lightning observation data of each area of the terrain to be evaluated, the calculation formula for the induced lightning trip rate is as follows:

[0039]

[0040] y max = 25H C I / U 50％ (12)

[0041]

[0042]

[0043] In the formula, P g is the induced lightning trip rate, D k is the distance from the direct strike point to the line, r c is the conductor striking distance, r g is the ground striking distance, H C is the distance from the tower conductor suspension point to the ground, y max is the flashover range of induced lightning, I is the induced lightning current, U 50％ is the 50% impulse flashover voltage of the insulator string, Ng is the cloud-to-ground flash density of each area of the terrain to be evaluated, η is the arc building rate, η = 0.4, I C is the lightning current amplitude, and P(I) is the probability distribution function of the lightning current amplitude;

[0044] According to the backflash trip rate, shielding failure trip rate and induced lightning trip rate, the calculation formula for the lightning trip rate of the transmission line in each area of the terrain to be evaluated is as follows:

[0045]

[0046] In the formula, S is the average value of the lightning trip rates of each tower of the transmission line in each area of the terrain to be evaluated, T is the total number of towers of the entire transmission line, m is the theoretically calculated lightning trip rate of the tower, m is the sum of the backflash trip rate, shielding failure trip rate and induced lightning trip rate, and n is the number of tower bases.

[0047] Furthermore, the specific method for evaluating the lightning strike risk of each area of the terrain to be evaluated through the lightning trip rate of the transmission line is:

[0048] When m < 0.5S, it is considered that the lightning strike risk level of the towers in each area of the terrain to be evaluated is Class I;

[0049] When 0.5S < m < S, it is considered that the lightning strike risk level of the towers in each area of the terrain to be evaluated is Class II;

[0050] When S < m < 1.5S, it is considered that the lightning strike risk level of the transmission towers in each area of the terrain to be evaluated is level III;

[0051] When m > 1.5S, it is considered that the lightning strike risk level of the transmission towers in each area of the terrain to be evaluated is level IV.

[0052] The second aspect of the present invention proposes a method for evaluating the lightning strike risk of a transmission line, including:

[0053] Dividing the mountain body and the flat area outside the critical area of the mountain body into several extraction sections, dividing the boundary of the mesoscopic terrain according to the coefficient of variation of the cloud-to-ground flash density of the extraction sections, and dividing the range from the boundary of the mesoscopic terrain to the vertex of the mountain body into the mesoscopic-scale terrain;

[0054] Establishing a mesoscopic terrain lightning downward leader fractal development model according to the spatial electric field of the mesoscopic-scale terrain, and obtaining the ground lightning strike distribution of the mesoscopic terrain through simulation calculation of the mesoscopic terrain lightning downward leader fractal development model;

[0055] Taking the ground lightning strike distribution of the mesoscopic terrain as the cloud-to-ground flash density of each area of the terrain to be evaluated, calculating the lightning trip rate of the transmission line in each area of the terrain to be evaluated according to the cloud-to-ground flash density and lightning observation data of each area of the terrain to be evaluated, and evaluating the lightning strike risk of each area of the terrain to be evaluated through the lightning trip rate of the transmission line.

[0056] Further, the specific method for dividing the mountain body and the flat area outside the critical area of the mountain body into several extraction sections is: taking the three-dimensional space formed by the width of the mountain body, the height of the mountain body, and the flat area outside the critical area of the mountain body as the research space for mesoscopic terrain scale division, and dividing the research space into several extraction sections with the same distance in the extraction direction along the extraction direction from the flat area to the mountain area.

[0057] Further, the specific method for dividing the boundary of the mesoscopic terrain according to the coefficient of variation of the cloud-to-ground flash density of the extraction sections and the average coefficient of variation of the cloud-to-ground flash density of the flat area is: calculating the coefficient of variation of the cloud-to-ground flash density of several extraction sections respectively, and comparing the obtained coefficients of variation of the cloud-to-ground flash density of several extraction sections with the average coefficient of variation of the cloud-to-ground flash density of the flat area in the research space. If the coefficient of variation of the cloud-to-ground flash density of the extraction section is greater than the coefficient of variation of the cloud-to-ground flash density of the flat area, then the extraction section is the critical section of the mesoscopic terrain scale in the research space, and the midpoint of the critical section is used as the boundary of the mesoscopic terrain.

[0058] Furthermore, a specific method for establishing a mesoscopic terrain lightning downward leader fractal development model based on the spatial electric field of the mesoscopic terrain is as follows: the mesoscopic terrain is divided into a grid with discrete grid points of equal spacing, and the potential relationship of the spatial electric field formed by each discrete grid point in the grid is shown in the following formula:

[0059]

[0060] In the formula, is the potential of the grid point at the i-th row and j-th column in the grid, is the potential of the grid point at the i+1th row and jth column in the grid, is the potential of the grid point at the i-th row and j+1-th column in the grid, is the potential of the grid point at the i-th row and j-1-th column in the grid, is the potential of the grid point at the i-1th row and jth column in the grid;

[0061] Formula (1) is calculated using the super-relaxation iteration method, and the potential relationship of the spatial electric field of the grid after iteration is shown as follows:

[0062]

[0063] In the formula, After the nth iteration The value of ω is the relaxation factor, After the n+1th iteration The value of After the n+1th iteration The value of After the n+1th iteration The value of After the n+1th iteration The value of After the n+1th iteration The value of

[0064] The calculation formula of the optimal relaxation factor that makes the iterative process converge fastest in formula (2) is as follows:

[0065]

[0066] Where ω0 is the optimal relaxation factor, n and m are the number of grids divided by the length and width of the mesoscopic terrain in the rectangular area, respectively;

[0067] The potential development point of the lightning downward leader is determined according to the discharge grid points inside the lightning discharge channel in the mesoscopic terrain. The determination formula is as follows:

[0068]

[0069] Where E is the average field strength between the discharge grid point inside the lightning discharge channel and the potential development point of the lightning leader. is the potential difference between the discharge grid point inside the lightning discharge channel and the potential development point of the downward leader of the lightning, L is the actual distance between the discharge grid point inside the lightning discharge channel and the potential development point of the downward leader of the lightning, E c is the critical discharge field strength, E c =216kV / m;

[0070] The probability of the development of the potential development point of the downward leader of lightning is as follows:

[0071]

[0072] In the formula, The discharge grid point N inside the lightning discharge channel develops to the potential development point N of the lightning downward leader * The probability of The distance from the discharge grid point N inside the lightning discharge channel to the potential development point N of the lightning downward leader * The electric field strength between them, η is the development probability index, E c is the critical discharge field strength, E c =216kV / m;

[0073] The potential development point of the downward leader of lightning develops into a discharge grid point inside a new lightning discharge channel. The potential calculation formula of the potential development point of the downward leader of lightning is as follows:

[0074]

[0075] In the formula, The potential of the potential development point N* of the downward leader of the lightning that develops into a new lightning discharge channel, is the potential of the discharge grid point N inside the lightning discharge channel, E ch is the electric field strength inside the new lightning discharge channel, From the discharge grid point N to the potential development point N * The distance between.

[0076] Furthermore, the specific method for calculating the lightning trip rate of the transmission line in each area of ​​the terrain to be evaluated according to the ground lightning density and lightning observation data in each area of ​​the terrain to be evaluated is as follows: the calculation formula for the strike-back trip rate is obtained according to the ground lightning density and lightning observation data in each area of ​​the terrain to be evaluated:

[0077] P f =N×g×P I ×η (7)

[0078]

[0079] Where P f is the strike tripping rate, N is the total number of annual lightning strikes in the divided mesoscopic terrain, g is the pole striking rate, which is 1 / 6 in plains and 1 / 4 in mountainous areas, and P I is the probability of a lightning current greater than I, η is the arcing rate, η=0.4, N g is the density of ground lightning in each area of ​​the terrain to be evaluated, b is the distance between two lightning conductors, and h is the height of the lightning conductor above the ground;

[0080] The calculation formula for the shielding failure trip rate is obtained based on the lightning density and lightning observation data in each area of ​​the terrain to be evaluated as follows:

[0081]

[0082] f(I)=I max (0.1r max ) 1.54 (10)

[0083] Where P r is the interruption tripping rate, η is the arcing rate, η=0.4, ΔL is the collector line section with a length of ΔL, N g is the density of ground-to-ground lightning in each area of ​​the terrain to be evaluated, I max is the maximum current amplitude of the shielding flashover, I C is the lightning current amplitude, l BD is the lightning exposure width, f(I) is the lightning current probability density function, r max is the maximum impact distance;

[0084] The calculation formula for the induced lightning trip rate is obtained based on the ground lightning density and lightning observation data in each area of ​​the terrain to be evaluated as follows:

[0085]

[0086] y max =25H c I / U 50％ (12)

[0087]

[0088]

[0089] Where P g is the induced lightning trip rate, D k is the distance from the direct hit point to the line, r c is the conductor striking distance, r g is the earth strike distance, H C y is the distance from the tower conductor suspension point to the ground, maxFor the flashover range of induced lightning, I is the induced lightning current, U 50％ The 50% impulse flashover voltage of the insulator string, N g For the ground flash density of each area of the terrain to be evaluated, η is the arc - building rate, η = 0.4, I C Is the lightning current amplitude, and P(I) is the probability distribution function of the lightning current amplitude;

[0090] According to the back - strike tripping rate, shielding failure tripping rate and induced lightning tripping rate, the calculation formula for the lightning tripping rate of the transmission line in each area of the terrain to be evaluated is as follows:

[0091]

[0092] In the formula, S is the average value of the lightning tripping rate of each tower of the transmission line in each area of the terrain to be evaluated, T is the total number of towers of the entire transmission line, m is the theoretically calculated lightning tripping rate of the tower, m is the sum of the back - strike tripping rate, shielding failure tripping rate and induced lightning tripping rate, and n is the number of tower bases.

[0093] Furthermore, the specific method for evaluating the lightning strike risk of each area of the terrain to be evaluated through the lightning tripping rate of the transmission line is as follows:

[0094] When m < 0.5S, it is considered that the lightning strike risk level of the towers in each area of the terrain to be evaluated is Class I;

[0095] When 0.5S < m < S, it is considered that the lightning strike risk level of the towers in each area of the terrain to be evaluated is Class II;

[0096] When S < m < 1.5S, it is considered that the lightning strike risk level of the towers in each area of the terrain to be evaluated is Class III;

[0097] When m > 1.5S, it is considered that the lightning strike risk level of the towers in each area of the terrain to be evaluated is Class IV.

[0098] The third aspect of the present invention proposes a computer - readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the steps of the above - mentioned method.

[0099] The beneficial effects of the present invention:

[0100] The traditional method of evaluating the lightning strike risk of transmission lines only considers the distribution of ground lightning in macro-terrain, but does not consider the terrain changes within the region, or only considers the influence of micro-terrain on lightning shielding rate, while ignoring the influence of micro-terrain on ground lightning distribution. Therefore, the present invention first divides the complex terrain area into mesoscale, and establishes a lightning downward leader fractal development model according to the divided mesoscale terrain, and then simulates and calculates the lightning downward leader fractal development model to obtain the ground lightning density in each area of ​​the mesoscale terrain, and finally calculates the lightning tripping rate of the transmission line in the complex terrain area through the ground lightning density in each area of ​​the mesoscale terrain and lightning observation data, thereby evaluating the lightning strike risk. The present invention is a ground lightning distribution in the mesoscale terrain between the macro-terrain and the micro-terrain, and integrates the lightning strike risk assessment method of the complex area transmission line in the mesoscale terrain, which provides technical support for the lightning strike risk assessment of the complex terrain transmission line, and uses the method to evaluate the lightning strike risk of the transmission line in the complex terrain area, divide the lightning strike risk level, and provide assistance for the lightning protection construction of the transmission line in the complex terrain area. BRIEF DESCRIPTION OF THE DRAWINGS

[0101] Figure 1 A structural block diagram of a transmission line lightning strike risk assessment system of the present invention;

[0102] Figure 2 This is a schematic diagram of the mesoscopic terrain scale division in the present invention;

[0103] Figure 3 This is a schematic diagram of the fractal development model of the downward leader of mesoscopic terrain lightning in the present invention;

[0104] Figure 4 This is a flow chart of the simulation of the distribution law of ground lightning in the intermediate terrain of the present invention;

[0105] Figure 5 It is a schematic diagram of the lightning tripping rate of each base tower of the power transmission line in the complex terrain area in the present invention. DETAILED DESCRIPTION

[0106] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0107] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0108] Example 1

[0109] The first aspect of the present invention provides a transmission line lightning risk assessment system, such as Figure 1 As shown, it includes a terrain scale division module, a ground lightning distribution module and a lightning strike risk assessment module;

[0110] The terrain scale division module is used to divide the mountain and the flat area outside the critical area of ​​the mountain into a number of extraction sections, divide the boundary of the mesoscopic terrain according to the ground lightning density variation coefficient of the extraction section and the average ground lightning density variation coefficient of the flat area, and divide the range from the boundary of the mesoscopic terrain to the top of the mountain into the mesoscopic scale terrain;

[0111] The ground lightning distribution module is used to establish a mesoscopic terrain lightning downward leader fractal development model according to the spatial electric field of the mesoscopic terrain, and obtain the mesoscopic terrain ground lightning distribution by simulating and calculating the mesoscopic terrain lightning downward leader fractal development model;

[0112] The lightning risk assessment module is used to use the ground lightning distribution of the mesoscopic terrain as the ground lightning density of each area of ​​the terrain to be assessed, calculate the lightning tripping rate of the transmission line in each area of ​​the terrain to be assessed according to the ground lightning density and lightning observation data of each area of ​​the terrain to be assessed, and assess the lightning risk of each area of ​​the terrain to be assessed through the transmission line lightning tripping rate.

[0113] In the above technical solution, the mountain transitions to the flat area through the critical area.

[0114] In the above technical solution, the system also includes a data acquisition module, which mainly collects mesoscopic terrain data and lightning observation data. The mesoscopic terrain data includes the ground-to-ground lightning density standard deviation σ and the ground-to-ground lightning density average μ of the extraction section and the flat area; the lightning observation data includes the lightning density and the lightning current amplitude probability, wherein the calculation formula of the lightning density is as follows:

[0115]

[0116] Where N L is the number of lightning strikes per square kilometer per year; T d is the annual average number of thunderstorm days, for T d =40 areas, N L =0.07, for T d =80 areas, N L =0.086.

[0117] In the above technical solution, the calculation formula for the probability distribution of lightning current amplitude is as follows:

[0118]

[0119] In the above technical solution, the correction formula for the annual average number of thunderstorm days below 20 is as follows:

[0120]

[0121] Where, I is the lightning current amplitude, kA; P L is the probability of a lightning current amplitude greater than I, %.

[0122] In the above technical solution, the calculation formula of the ground-to-ground flash density variation coefficient is as follows:

[0123]

[0124] In the formula, C v is the coefficient of variation of ground-to-ground flash density, σ is the standard deviation of ground-to-ground flash density, and μ is the average ground-to-ground flash density.

[0125] In the above technical solution, the specific method of dividing the mountain and the flat area around the mountain into several extraction segments is: taking the three-dimensional space formed by the width of the mountain, the height of the mountain, and the flat area from the mountain to the surrounding area as the research space for mesoscopic terrain scale division, and dividing the research space along the extraction direction from the flat area to the mountain area into several extraction segments with the same distance in the extraction direction. For example, the research space is a three-dimensional space, the flat area from the mountain to the surrounding area is the x-axis, the width of the mountain is the y-axis, and the height of the mountain is the z-axis. In this article, the same distance refers to dividing the x-axis into segments of the same length, such as Figure 2 Extraction section 1, extraction section 2 and extraction section 3 are shown.

[0126] In the above technical solution, the specific method for dividing the boundary of the mesoscopic terrain according to the ground-to-ground lightning density variation coefficient of the extracted section and the average ground-to-ground lightning density variation coefficient of the flat area is: respectively calculate the ground-to-ground lightning density variation coefficients of several extracted sections, and compare the ground-to-ground lightning density variation coefficients of several extracted sections with the average ground-to-ground lightning density variation coefficient of the flat area in the study space. If the ground-to-ground lightning density variation coefficient of the extracted section is greater than the ground-to-ground lightning density variation coefficient of the flat area, then the extracted section is the critical section of the mesoscopic terrain scale in the study space. Figure 2 As shown, the coefficient of variation of ground-to-ground lightning density in extracted section 3 is greater than the average coefficient of variation of ground-to-ground lightning density in the flat area. Therefore, extracted section 3 is taken as the critical section of the mesoscopic terrain scale.

[0127] According to the data from the lightning location system, the ground-to-ground lightning density map presents a curve similar to the contour lines in the topographic map. The distribution of lightning strikes in the flat area presents a uniform distribution, that is, the ground-to-ground lightning density in the flat area fluctuates in a smaller area near the mean, while the ground-to-ground lightning density in the mountain is significantly higher than that in the flat area. However, the mountain will have a shielding effect on the flat areas within a certain range nearby, which will cause the ground-to-ground lightning density in a certain part of the flat area near the foot of the mountain to be significantly lower than that in another part of the flat area. Therefore, the critical section will only appear in the flat area near the foot of the mountain, and the ground-to-ground lightning density in the farther flat area fluctuates in a smaller area near the mean.

[0128] In the above technical solution, the midpoint of the critical segment is used as the boundary of the mesoscopic topography. However, considering the randomness of the data, the midpoint of the extraction segment 3 and the extraction segment 2 is used as the boundary for dividing the mesoscopic topography. Figure 2 As shown in the figure, the scale range on the right side of the mesoscopic terrain is the distance from the midpoint of the extracted segment 2 to the top of the mountain; the scale range on the left side of the mesoscopic terrain can be divided by the same method, and the scale range of the entire mesoscopic terrain is the superposition of the left and right sides. Considering that there is only a flat area on one side of the actual terrain, when dividing the scale for this special case, the scale of the side with flat land is used as the scale range of the mesoscopic terrain.

[0129] In the present invention, the height and slope of the mountain have a significant impact on the results of the mesoscopic terrain scale division. Since the mountain has an attractive effect on lightning, it will have a shielding effect on the foot of the mountain, resulting in a decrease in the density of ground-to-ground lightning, thereby increasing the coefficient of variation of the ground-to-ground lightning density. Therefore, the higher the mountain height and the greater the mountain slope, the greater the mountain's attraction to lightning. At the same time, the shielding range of the foot of the mountain is expanded, and the point where the coefficient of variation of the ground-to-ground lightning density increases is further away from the mountain, ultimately resulting in the critical section of the mesoscopic terrain being farther away from the mountain, and the more obvious the impact of the terrain on the distribution of ground lightning strikes.

[0130] In the above technical scheme, the specific method of establishing the fractal development model of mesoscopic terrain lightning downward leader according to the spatial electric field of the mesoscopic terrain is as follows: the mountain model is replaced by an isosceles triangle. In order to facilitate the calculation of the spatial electric field, the space of the mesoscopic terrain is discretized into a series of equally spaced grid points. The entire space is divided into 5m×5m square grids, in which the mountain area is divided into finer 1m×1m square grids, and the endpoints of all grids are used to replace the entire research space, such as Figure 3 As shown, the potential relationship of the spatial electric field formed by each discrete grid point in the grid is shown as follows:

[0131]

[0132] In the formula, is the potential of the grid point at the i-th row and j-th column in the grid, is the potential of the grid point at the i+1th row and jth column in the grid, is the potential of the grid point at the i-th row and j+1-th column in the grid, is the potential of the grid point at the i-th row and j-1-th column in the grid, is the potential of the grid point at the i-1th row and jth column in the grid.

[0133] In the above technical solution, the potential relationship of the spatial electric field formed by the above grid points is calculated using the super-relaxation iteration method, and the potential relationship of the spatial electric field of the grid after iteration is as shown in the following formula:

[0134]

[0135] In the formula, After the nth iteration The value of ω is the relaxation factor, After the n+1th iteration The value of After the n+1th iteration The value of After the n+1th iteration The value of After the n+1th iteration The value of After the n+1th iteration The spatial electric field of the grid after super-relaxation iteration provides the background field strength for the subsequent calculation of the fractal development model of the downward leader of mesoscopic terrain lightning.

[0136] In the above technical solution, the calculation formula of the optimal relaxation factor that makes the iterative process converge fastest in the above iterative formula is as follows:

[0137]

[0138] Where ω0 is the optimal relaxation factor, n and m are the number of grids divided by the length and width of the mesoscopic terrain in the rectangular area. Generally, the more grid nodes there are, the larger the optimal relaxation factor is. When the relaxation factor used is less than the optimal value, the convergence process is monotonic, and the convergence speed increases with the increase of the relaxation factor.

[0139] In the above technical solution, the downward leader of lightning starts to develop vertically from the upper boundary of the thundercloud to the ground, such as Figure 3As shown in the figure, the upper boundary of the thundercloud to the ground is simplified into a two-dimensional plane and divided into a dot matrix. Each step of the development process of the downward leader can be simplified as the development from the grid point inside the lightning discharge channel to the undischarged grid point within the specified step range around the lightning discharge channel. If the average field strength between the undischarged grid point and a point in the lightning discharge channel meets certain conditions, then the point is the potential development point of the downward leader of the lightning. Therefore, the potential development point of the downward leader of the lightning is judged according to the discharge grid point inside the lightning discharge channel in the mesoscopic terrain. The judgment formula is as follows:

[0140]

[0141] Where E is the average field strength between the discharge grid point inside the lightning discharge channel and the potential development point of the lightning leader. is the potential difference between the discharge grid point inside the lightning discharge channel and the potential development point of the downward leader of the lightning, L is the actual distance between the discharge grid point inside the lightning discharge channel and the potential development point of the downward leader of the lightning, E c is the critical discharge field strength, E c =216kV / m. In this paper, the lightning discharge channel is Figure 3 The line segments connecting the black solid circles in the middle, the discharge grid points are Figure 3 The black solid dots in Figure 3 The white dots in the figure are the undischarged grid points. Figure 3 When the average field strength between the white dot in the figure and the discharge grid points inside the lightning discharge channel meets the judgment formula for the potential development point of the downward leader of lightning, the white dot can be determined as the potential development point of the downward leader of lightning.

[0142] In the above technical solution, the probability of the development of the potential development point of the downward leader of lightning is as follows:

[0143]

[0144] In the formula, The discharge grid point N inside the lightning discharge channel develops to the potential development point N of the lightning downward leader * The probability of The distance from the discharge grid point N inside the lightning discharge channel to the potential development point N of the lightning downward leader * The electric field strength between them, η is the development probability index, η is 1, E c is the critical discharge field strength, E c =216kV / m.

[0145] In the above technical solution, the potential development point of the downward leader of lightning develops into a discharge grid point inside a new lightning discharge channel, and the potential calculation formula of the potential development point of the downward leader of lightning is as follows:

[0146]

[0147] In the formula, The potential development point N of the lightning leader that develops into a new lightning discharge channel * The potential, is the potential of the discharge grid point N inside the lightning discharge channel, E ch is the electric field strength inside the new lightning discharge channel, From the discharge grid point N to the potential development point N * The distance between.

[0148] In the above technical solution, the mesoscopic terrain lightning downward leader fractal development model is simulated and calculated to obtain the specific method of mesoscopic terrain ground lightning distribution: the development of the lightning downward leader fractal type is simulated by COMSOL simulation software, such as Figure 4 As shown, firstly, the thundercloud potential, the starting position of the leader and the development step length are input, and then the mountain modeling related parameters such as the mountain height and the mountain width are input, and the potential and the electric field strength of each grid point in the mesoscopic terrain are calculated, and the position and the potential of the potential development point of the lightning downward leader are continuously calculated through the mesoscopic terrain lightning downward leader fractal development model. When the potential development point of the lightning downward leader changes suddenly, the simulation of a lightning strike process is completed, and the above process is repeated until the simulation of t lightning strike processes is completed, and the coordinates of all lightning strike points are recorded to obtain the ground lightning distribution of the mesoscopic terrain. In this article, the judgment of the transition of the potential development point of the downward leader of lightning is as follows: when the average field strength between the upward and downward leaders or between the downward leader and a target object that has not produced an upward leader (the upward leader refers to a phenomenon caused by a strong electric field on the target object, and the criterion is used to determine whether the target object has produced an upward leader) exceeds the average critical field strength of 500kV / m or the upward and downward leaders meet, the final transition of the lightning strike occurs; the thundercloud potential is set to -200MV; the development step is set to 20m.

[0149] In the above technical solution, the specific method for calculating the lightning trip rate of the transmission line in each area of ​​the complex terrain according to the lightning density and lightning observation data of each area of ​​the terrain to be evaluated is: the calculation formula of the strike-back trip rate is obtained according to the lightning density and lightning observation data of each area of ​​the terrain to be evaluated as follows:

[0150] P f =N×g×P I ×η

[0151]

[0152] Where P fis the strike tripping rate, N is the total number of annual lightning strikes in the divided mesoscopic terrain, g is the pole striking rate, which is 1 / 6 in plains and 1 / 4 in mountainous areas, and P I is the probability of a lightning current greater than I, η is the arcing rate, η=0.4, N g is the density of ground lightning in each area of ​​the terrain to be evaluated, b is the distance between the two lightning conductors, and h is the height of the lightning conductor above the ground.

[0153] In the above technical solution, the calculation formula for the shielding failure tripping rate is obtained according to the lightning density and lightning observation data of each area of ​​the terrain to be evaluated as follows:

[0154]

[0155] f(I)=I max (0.1r max ) 1.54

[0156] Where P r is the interruption tripping rate, η is the arcing rate, η=0.4, ΔL is the collector line section with a length of ΔL, N g is the density of ground-to-ground lightning in each area of ​​the terrain to be evaluated, I max is the maximum current amplitude of the shielding flashover, I C is the lightning current amplitude, l BD is the lightning exposure width, f(I) is the lightning current probability density function, r max is the maximum impact distance.

[0157] In the above technical solution, the calculation formula for the induced lightning tripping rate is obtained according to the ground lightning density and lightning observation data of each area of ​​the terrain to be evaluated as follows:

[0158]

[0159] y max =25H C I / U 50％

[0160]

[0161]

[0162] Where P g is the induced lightning trip rate, D k is the distance from the direct hit point to the line, r c is the conductor striking distance, r g is the earth strike distance, H C y is the distance from the tower conductor suspension point to the ground, max is the flashover range of induced lightning, I is the induced lightning current, U 50％50% impulse flashover voltage of insulator string, N g is the ground flash density of each area of the terrain to be evaluated, η is the arc building rate, η = 0.4, I C is the lightning current amplitude, and P(I) is the probability distribution function of the lightning current amplitude.

[0163] In the above technical solution, the calculation formula for the lightning trip rate of the transmission line in each area of the terrain to be evaluated according to the back-strike trip rate, shielding failure trip rate and induced lightning trip rate is as follows:

[0164]

[0165] In the formula, S is the average value of the lightning trip rate of each tower of the transmission line in each area of the terrain to be evaluated, T is the total number of towers of the entire transmission line, m is the theoretically calculated lightning trip rate of the tower, m is the sum of the back-strike trip rate, shielding failure trip rate and induced lightning trip rate, and n is the number of tower bases.

[0166] In the above technical solution, the specific method for evaluating the lightning strike risk of each area of the complex terrain through the lightning trip rate of the transmission line is as follows: when m < 0.5S, it is considered that the lightning strike risk level of the towers in each area of the complex terrain is Class I, and Class I is a low risk; when 0.5S < m < S, it is considered that the lightning strike risk level of the towers in each area of the complex terrain is Class II, and Class II is a medium risk; when S < m < 1.5S, it is considered that the lightning strike risk level of the towers in each area of the complex terrain is Class III, and Class III is a high risk; when m > 1.5S, it is considered that the lightning strike risk level of the towers in each area of the complex terrain is Class IV, and Class IV is an extremely high risk.

[0167] Embodiment 2

[0168] The second aspect of the present invention proposes a method for evaluating the lightning strike risk of a transmission line, including:

[0169] Dividing the mountain and the flat areas around the mountain into several extraction sections, dividing the boundary of the meso-scale terrain according to the coefficient of variation of the ground flash density of the extraction sections, and dividing the range from the boundary of the meso-scale terrain to the vertex of the mountain into meso-scale terrain;

[0170] Establishing a meso-scale terrain lightning downward leader fractal development model according to the spatial electric field of the meso-scale terrain, and obtaining the meso-scale terrain ground lightning strike distribution through simulation calculation of the meso-scale terrain lightning downward leader fractal development model;

[0171] Taking the meso-scale terrain ground lightning strike distribution as the ground flash density of each area of the complex terrain, calculating the lightning trip rate of the transmission line in each area of the complex terrain according to the ground flash density and lightning observation data of each area of the terrain to be evaluated, and evaluating the lightning strike risk of each area of the complex terrain through the lightning trip rate of the transmission line.

[0172] In the above technical solution, the mountain transitions to the flat area through the critical area.

[0173] In the above technical solution, the system also includes a data acquisition module, which mainly collects mesoscopic terrain data and lightning observation data. The mesoscopic terrain data includes the ground-to-ground lightning density standard deviation σ and the ground-to-ground lightning density average μ of the extraction section and the flat area; the lightning observation data includes the lightning density and the lightning current amplitude probability, wherein the calculation formula of the lightning density is as follows:

[0174]

[0175] Where N L is the number of lightning strikes per square kilometer per year; T d is the annual average number of thunderstorm days, for T d =40 areas, N L =0.07, for T d =80 areas, N L =0.086.

[0176] In the above technical solution, the calculation formula for the probability distribution of lightning current amplitude is as follows:

[0177]

[0178] In the above technical solution, the correction formula for the annual average number of thunderstorm days below 20 is as follows:

[0179]

[0180] Where, I is the lightning current amplitude, kA; P L is the probability of a lightning current amplitude greater than I, %.

[0181] In the above technical solution, the calculation formula of the ground-to-ground flash density variation coefficient is as follows:

[0182]

[0183] In the formula, C v is the coefficient of variation of ground-to-ground flash density, σ is the standard deviation of ground-to-ground flash density, and μ is the average ground-to-ground flash density.

[0184] In the above technical solution, the specific method of dividing the mountain and the flat area around the mountain into several extraction segments is: taking the three-dimensional space formed by the width of the mountain, the height of the mountain, and the flat area from the mountain to the surrounding area as the research space for mesoscopic terrain scale division, and dividing the research space along the extraction direction from the flat area to the mountain area into several extraction segments with the same distance in the extraction direction. For example, the research space is a three-dimensional space, the flat area from the mountain to the surrounding area is the x-axis, the width of the mountain is the y-axis, and the height of the mountain is the z-axis. In this article, the same distance refers to dividing the x-axis into segments of the same length, such as Figure 2 Extraction section 1, extraction section 2 and extraction section 3 are shown.

[0185] In the above technical solution, the specific method for dividing the boundary of the mesoscopic terrain according to the ground-to-ground lightning density variation coefficient of the extracted section and the average ground-to-ground lightning density variation coefficient of the flat area is: respectively calculate the ground-to-ground lightning density variation coefficients of several extracted sections, and compare the ground-to-ground lightning density variation coefficients of several extracted sections with the average ground-to-ground lightning density variation coefficient of the flat area in the study space. If the ground-to-ground lightning density variation coefficient of the extracted section is greater than the ground-to-ground lightning density variation coefficient of the flat area, then the extracted section is the critical section of the mesoscopic terrain scale in the study space. Figure 2 As shown, the coefficient of variation of ground-to-ground lightning density in extracted section 3 is greater than the average coefficient of variation of ground-to-ground lightning density in the flat area. Therefore, extracted section 3 is taken as the critical section of the mesoscopic terrain scale.

[0186] According to the data from the lightning location system, the ground-to-ground lightning density map presents a curve similar to the contour lines in the topographic map. The distribution of lightning strikes in the flat area presents a uniform distribution, that is, the ground-to-ground lightning density in the flat area fluctuates in a smaller area near the mean, while the ground-to-ground lightning density in the mountain is significantly higher than that in the flat area. However, the mountain will have a shielding effect on the flat areas within a certain range nearby, which will cause the ground-to-ground lightning density in a certain part of the flat area near the foot of the mountain to be significantly lower than that in another part of the flat area. Therefore, the critical section will only appear in the flat area near the foot of the mountain, and the ground-to-ground lightning density in the farther flat area fluctuates in a smaller area near the mean.

[0187] In the above technical solution, the midpoint of the critical segment is used as the boundary of the mesoscopic topography. However, considering the randomness of the data, the midpoint of the extraction segment 3 and the extraction segment 2 is used as the boundary for dividing the mesoscopic topography. Figure 2As shown in the figure, the scale range on the right side of the mesoscopic terrain is the distance from the midpoint of the extracted segment 2 to the top of the mountain; the scale range on the left side of the mesoscopic terrain can be divided by the same method, and the scale range of the entire mesoscopic terrain is the superposition of the left and right sides. Considering that there is only a flat area on one side of the actual terrain, when dividing the scale for this special case, the scale of the side with flat land is used as the scale range of the mesoscopic terrain.

[0188] In the present invention, the height and slope of the mountain have a significant impact on the results of the mesoscopic terrain scale division. Since the mountain has an attractive effect on lightning, it will have a shielding effect on the foot of the mountain, resulting in a decrease in the density of ground-to-ground lightning, thereby increasing the coefficient of variation of the ground-to-ground lightning density. Therefore, the higher the mountain height and the greater the mountain slope, the greater the mountain's attraction to lightning. At the same time, the shielding range of the foot of the mountain is expanded, and the point where the coefficient of variation of the ground-to-ground lightning density increases is further away from the mountain, ultimately resulting in the critical section of the mesoscopic terrain being farther away from the mountain, and the more obvious the impact of the terrain on the distribution of ground lightning strikes.

[0189] In the above technical scheme, the specific method of establishing the fractal development model of mesoscopic terrain lightning downward leader according to the spatial electric field of the mesoscopic terrain is as follows: the mountain model is replaced by an isosceles triangle. In order to facilitate the calculation of the spatial electric field, the space of the mesoscopic terrain is discretized into a series of equally spaced grid points. The entire space is divided into 5m×5m square grids, in which the mountain area is divided into finer 1m×1m square grids, and the endpoints of all grids are used to replace the entire research space, such as Figure 3 As shown, the potential relationship of the spatial electric field formed by each discrete grid point in the grid is shown as follows:

[0190]

[0191] In the formula, is the potential of the grid point at the i-th row and j-th column in the grid, is the potential of the grid point at the i+1th row and jth column in the grid, is the potential of the grid point at the i-th row and j+1-th column in the grid, is the potential of the grid point at the i-th row and j-1-th column in the grid, is the potential of the grid point at the i-1th row and jth column in the grid.

[0192] In the above technical solution, the potential relationship of the spatial electric field formed by the above grid points is calculated using the super-relaxation iteration method, and the potential relationship of the spatial electric field of the grid after iteration is as shown in the following formula:

[0193]

[0194] In the formula, After the nth iteration The value of ω is the relaxation factor, After the n+1th iteration The value of After the n+1th iteration The value of After the n+1th iteration The value of After the n+1th iteration The value of After the n+1th iteration The spatial electric field of the grid after super-relaxation iteration provides the background field strength for the subsequent calculation of the fractal development model of the downward leader of mesoscopic terrain lightning.

[0195] In the above technical solution, the calculation formula of the optimal relaxation factor that makes the iterative process converge fastest in the above iterative formula is as follows:

[0196]

[0197] Where ω0 is the optimal relaxation factor, n and m are the number of grids divided by the length and width of the mesoscopic terrain in the rectangular area. Generally, the more grid nodes there are, the larger the optimal relaxation factor is. When the relaxation factor used is less than the optimal value, the convergence process is monotonic, and the convergence speed increases with the increase of the relaxation factor.

[0198] In the above technical solution, the downward leader of lightning starts to develop vertically from the upper boundary of the thundercloud to the ground, such as Figure 3 As shown in the figure, the upper boundary of the thundercloud to the ground is simplified into a two-dimensional plane and divided into a dot matrix. Each step of the development process of the downward leader can be simplified as the development from the grid point inside the lightning discharge channel to the undischarged grid point within the specified step range around the lightning discharge channel. If the average field strength between the undischarged grid point and a point in the lightning discharge channel meets certain conditions, then the point is the potential development point of the downward leader of the lightning. Therefore, the potential development point of the downward leader of the lightning is judged according to the discharge grid point inside the lightning discharge channel in the mesoscopic terrain. The judgment formula is as follows:

[0199]

[0200] Where E is the average field strength between the discharge grid point inside the lightning discharge channel and the potential development point of the lightning leader. is the potential difference between the discharge grid point inside the lightning discharge channel and the potential development point of the downward leader of the lightning, L is the actual distance between the discharge grid point inside the lightning discharge channel and the potential development point of the downward leader of the lightning, E c is the critical discharge field strength, E c =216kV / m. In this paper, the lightning discharge channel is Figure 3The line segments connecting the black solid circles in the middle, the discharge grid points are Figure 3 The black solid dots in Figure 3 The white dots in the figure are the undischarged grid points. Figure 3 When the average field strength between the white dot in the figure and the discharge grid points inside the lightning discharge channel meets the judgment formula for the potential development point of the downward leader of lightning, the white dot can be determined as the potential development point of the downward leader of lightning.

[0201] In the above technical solution, the probability of the development of the potential development point of the downward leader of lightning is as follows:

[0202]

[0203] In the formula, The discharge grid point N inside the lightning discharge channel develops to the potential development point N of the lightning downward leader * The probability of The distance from the discharge grid point N inside the lightning discharge channel to the potential development point N of the lightning downward leader * The electric field strength between them, η is the development probability index, η is 1, E c is the critical discharge field strength, E c =216kV / m.

[0204] In the above technical solution, the potential development point of the downward leader of lightning develops into a discharge grid point inside a new lightning discharge channel, and the potential calculation formula of the potential development point of the downward leader of lightning is as follows:

[0205]

[0206] In the formula, The potential development point N of the lightning leader that develops into a new lightning discharge channel * The potential, is the potential of the discharge grid point N inside the lightning discharge channel, E ch is the electric field strength inside the new lightning discharge channel, From the discharge grid point N to the potential development point N * The distance between.

[0207] In the above technical solution, the mesoscopic terrain lightning downward leader fractal development model is simulated and calculated to obtain the specific method of mesoscopic terrain ground lightning distribution: the development of the lightning downward leader fractal type is simulated by COMSθL simulation software, such as Figure 4As shown, firstly, the thundercloud potential, the starting position of the leader and the development step length are input, and then the mountain modeling related parameters such as the mountain height and the mountain width are input, and the potential and the electric field strength of each grid point in the mesoscopic terrain are calculated, and the position and the potential of the potential development point of the lightning downward leader are continuously calculated through the mesoscopic terrain lightning downward leader fractal development model. When the potential development point of the lightning downward leader changes suddenly, the simulation of a lightning strike process is completed, and the above process is repeated until the simulation of t lightning strike processes is completed, and the coordinates of all lightning strike points are recorded to obtain the ground lightning distribution of the mesoscopic terrain. In this article, the judgment of the transition of the potential development point of the downward leader of lightning is as follows: when the average field strength between the upward and downward leaders or between the downward leader and a target object that has not produced an upward leader (the upward leader refers to a phenomenon caused by a strong electric field on the target object, and the criterion is used to determine whether the target object has produced an upward leader) exceeds the average critical field strength of 500kV / m or the upward and downward leaders meet, the final transition of the lightning strike occurs; the thundercloud potential is set to -200MV; the development step is set to 20m.

[0208] In the above technical solution, the specific method for calculating the lightning trip rate of the transmission line in each area of ​​the complex terrain according to the lightning density and lightning observation data of each area of ​​the terrain to be evaluated is: the calculation formula of the strike-back trip rate is obtained according to the lightning density and lightning observation data of each area of ​​the terrain to be evaluated as follows:

[0209] P f =N×g×P I ×η

[0210]

[0211] Where P f is the strike tripping rate, N is the total number of annual lightning strikes in the divided mesoscopic terrain, g is the pole striking rate, which is 1 / 6 in plains and 1 / 4 in mountainous areas, and P I is the probability of a lightning current greater than I, η is the arcing rate, η=0.4, N g is the density of ground lightning in each area of ​​the terrain to be evaluated, b is the distance between the two lightning conductors, and h is the height of the lightning conductor above the ground.

[0212] In the above technical solution, the calculation formula for the shielding failure tripping rate is obtained according to the lightning density and lightning observation data of each area of ​​the terrain to be evaluated as follows:

[0213]

[0214] f(I)=I max (0.1r max ) 1.54

[0215] Where P ris the interruption tripping rate, η is the arcing rate, η=0.4, ΔL is the collector line section with a length of ΔL, N g is the density of ground-to-ground lightning in each area of ​​the terrain to be evaluated, I max is the maximum current amplitude of the shielding flashover, I C is the lightning current amplitude, l BD is the lightning exposure width, f(I) is the lightning current probability density function, r max is the maximum impact distance.

[0216] In the above technical solution, the calculation formula for the induced lightning tripping rate is obtained according to the ground lightning density and lightning observation data of each area of ​​the terrain to be evaluated as follows:

[0217]

[0218] y max =25H C I / U 50％

[0219]

[0220]

[0221] Where P g is the induced lightning trip rate, D k is the distance from the direct hit point to the line, r c is the conductor striking distance, r g is the earth strike distance, H C y is the distance from the tower conductor suspension point to the ground, max is the flashover range of induced lightning, I is the induced lightning current, U 50％ Insulator string 50% impulse flashover voltage, N g is the density of ground-to-ground lightning in each area of ​​the terrain to be evaluated, η is the arcing rate, η=0.4, I C is the lightning current amplitude, and P(I) is the lightning current amplitude distribution probability function.

[0222] In the above technical solution, the calculation formula for the lightning trip rate of the power transmission line in each area of ​​the terrain to be evaluated is obtained according to the counter-tripping, shielding failure tripping rate and induced lightning tripping rate as follows:

[0223]

[0224] Where S is the average value of the lightning tripping rate of each base tower of the transmission line in each area of ​​the terrain to be evaluated, T is the total number of towers of the entire transmission line, m is the theoretically calculated lightning tripping rate of the tower, m is the sum of the strike tripping rate, the shielding tripping rate and the induced lightning tripping rate, and n is the number of towers.

[0225] In the above technical solution, the specific method for evaluating the lightning strike risk of each area in complex terrain through the lightning trip rate of the transmission line is as follows: when m < 0.5S, it is considered that the lightning strike risk level of the towers in each area of the complex terrain is level I, and level I is a low risk; when 0.5S < m < S, it is considered that the lightning strike risk level of the towers in each area of the complex terrain is level II, and level II is a medium risk; when S < m < 1.5S, it is considered that the lightning strike risk level of the towers in each area of the complex terrain is level III, and level III is a high risk; when m > 1.5S, it is considered that the lightning strike risk level of the towers in each area of the complex terrain is level IV, and level IV is an extremely high risk.

[0226] Embodiment 3

[0227] The third aspect of the present invention proposes a computer-readable storage medium, which stores a computer program, and when the computer program is executed by a processor, it implements the steps of the above method.

[0228] The present invention first selects a transmission line in a high-altitude mountainous area as the research object, uses a geographic information system to collect data on mesoscopic terrain within the transmission line corridor, calculates the change in ground flash density around the mountain body, establishes a mesoscopic terrain area, calculates the ground flash density within the mesoscopic area, and then establishes a lightning fractal calculation model based on the lightning-related data within the area. At the same time, for the transmission line, considering factors such as the line position, ground inclination, and tower parameters, a line model is established. Finally, the shielding failure, back flashover, and induced lightning trip rates of the transmission line are calculated, and the lightning trip rate of each tower is calculated, and finally the lightning risk assessment of the entire transmission line is completed.

[0229] Those skilled in the art should understand that the embodiments of the present invention can be provided as methods, systems, or computer-readable storage media. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer-readable storage medium implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0230] The present invention is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer-readable storage media according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, and the combination of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to the processors of general-purpose computers, special-purpose computers, embedded processors, or other programmable data processing devices to generate a machine, so that the instructions executed by the processors of the computer or other programmable data processing devices generate for implementation in the process Figure 1 A process or multiple processes and / or boxes Figure 1 A system that specifies the functions of a box or multiple boxes.

[0231] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory produce a product including an instruction system, which is implemented in the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0232] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0233] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit its protection scope. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that after reading the present invention, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the invention, but these changes, modifications or equivalent substitutions are all within the protection scope of the pending claims of the invention.

[0234] 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 transmission line lightning risk assessment system, characterized in that: include: A terrain scale division module is used to divide the mountain and the flat area outside the critical area of ​​the mountain into a number of extraction sections, divide the boundary of the mesoscopic terrain according to the ground lightning density variation coefficient of the extraction section and the average ground lightning density variation coefficient of the flat area, and divide the range from the boundary of the mesoscopic terrain to the top of the mountain into the mesoscopic scale terrain; A ground lightning distribution module is used to establish a mesoscopic terrain lightning downward leader fractal development model according to the spatial electric field of the mesoscopic terrain, and obtain the mesoscopic terrain ground lightning distribution by simulating and calculating the mesoscopic terrain lightning downward leader fractal development model; The lightning risk assessment module is used to use the ground lightning distribution of the mesoscopic terrain as the ground lightning density of each area of ​​the terrain to be assessed, calculate the lightning tripping rate of the transmission line in each area of ​​the terrain to be assessed according to the ground lightning density and lightning observation data of each area of ​​the terrain to be assessed, and assess the lightning risk of each area of ​​the terrain to be assessed through the transmission line lightning tripping rate.

2. The transmission line lightning risk assessment system according to claim 1, characterized in that: The specific method for dividing the mountain and the flat area outside the critical area of ​​the mountain into several extraction segments is: using the three-dimensional space formed by the width of the mountain, the height of the mountain, and the flat area from the mountain to the critical area of ​​the mountain as the research space for mesoscopic terrain scale division, and dividing the research space along the extraction direction from the flat area to the mountain area into several extraction segments with the same distance in the extraction direction.

3. The transmission line lightning risk assessment system according to claim 2, characterized in that: The specific method for dividing the boundary of the mesoscopic terrain according to the ground-to-ground lightning density variation coefficient of the extracted section and the average ground-to-ground lightning density variation coefficient of the flat area is: respectively calculate the ground-to-ground lightning density variation coefficients of several of the extracted sections, and compare the ground-to-ground lightning density variation coefficients of the several extracted sections obtained with the average ground-to-ground lightning density variation coefficient of the flat area in the study space; if the ground-to-ground lightning density variation coefficient of the extracted section is greater than the ground-to-ground lightning density variation coefficient of the flat area, then the extracted section is the critical section of the mesoscopic terrain scale in the study space, and the midpoint of the critical section is taken as the boundary of the mesoscopic terrain.

4. The transmission line lightning risk assessment system according to claim 3, characterized in that: The specific method of establishing the fractal development model of the downward leader of lightning in mesoscopic terrain according to the spatial electric field of the mesoscopic terrain is: dividing the mesoscopic terrain into a grid with discrete grid points of equal spacing, and the potential relationship of the spatial electric field formed by each discrete grid point in the grid is shown in the following formula: In the formula, is the potential of the grid point at the i-th row and j-th column in the grid, is the potential of the grid point at the i+1th row and jth column in the grid, is the potential of the grid point at the i-th row and j+1-th column in the grid, is the potential of the grid point at the i-th row and j-1-th column in the grid, is the potential of the grid point at the i-1th row and jth column in the grid; Formula (1) is calculated by super-relaxation iteration method, and the potential relationship of the spatial electric field of the grid after iteration is shown as follows: In the formula, After the nth iteration The value of ω is the relaxation factor, After the n+1th iteration The value of After the n+1th iteration The value of After the n+1th iteration The value of After the n+1th iteration The value of After the n+1th iteration The value of The calculation formula of the optimal relaxation factor that makes the iterative process converge fastest in formula (2) is as follows: Where ω0 is the optimal relaxation factor, n and m are the number of grids divided by the length and width of the rectangular area of ​​the mesoscopic terrain, respectively; The potential development point of the lightning downward leader is determined according to the discharge grid points inside the lightning discharge channel in the mesoscopic terrain. The determination formula is as follows: Where E is the average field strength between the discharge grid point inside the lightning discharge channel and the potential development point of the lightning leader. is the potential difference between the discharge grid point inside the lightning discharge channel and the potential development point of the downward leader of the lightning, L is the actual distance between the discharge grid point inside the lightning discharge channel and the potential development point of the downward leader of the lightning, E c is the critical discharge field strength, E c =216kV / m; The probability of the development of the potential development point of the downward leader of lightning is as follows: In the formula, The discharge grid point N inside the lightning discharge channel develops to the potential development point N of the lightning downward leader * The probability of The distance from the discharge grid point N inside the lightning discharge channel to the potential development point N of the lightning downward leader * The electric field strength between them, η is the development probability index, E c is the critical discharge field strength, E c =216kV / m; The potential development point of the downward leader of lightning develops into a discharge grid point inside a new lightning discharge channel. The potential calculation formula of the potential development point of the downward leader of lightning is as follows: In the formula, The potential development point N of the lightning leader that develops into a new lightning discharge channel * The potential, is the potential of the discharge grid point N inside the lightning discharge channel, E ch is the electric field strength inside the new lightning discharge channel, From the discharge grid point N to the potential development point N * The distance between.

5. The power transmission line lightning strike risk assessment system according to claim 4, characterized in that: The specific method for performing simulation calculations on the mesoscopic terrain lightning downward leader fractal development model to obtain the mesoscopic terrain ground lightning strike distribution is as follows: Calculate the potential and electric field strength of each grid point in the mesoscopic scale terrain, and continuously calculate the position and potential of the potential development points of the lightning downward leader through the mesoscopic terrain lightning downward leader fractal development model. When a jump occurs at the potential development points of the lightning downward leader, the simulation of one lightning strike process is completed. Repeat the above process until the simulation of t lightning strike processes is completed, and record the coordinates of all lightning strike points to obtain the mesoscopic terrain ground lightning strike distribution.

6. The power transmission line lightning risk assessment system according to claim 5, characterized in that: The specific method for calculating the lightning trip rate of transmission lines in each area of the terrain to be evaluated based on the cloud-to-ground flash density and lightning observation data in each area of the terrain to be evaluated is as follows: The calculation formula for the back flashover trip rate is obtained based on the cloud-to-ground flash density and lightning observation data in each area of the terrain to be evaluated as shown below: P f =N×g×P I ×η (7) Where P f is the strike tripping rate, N is the total number of annual lightning strikes in the divided mesoscopic terrain, g is the pole striking rate, which is 1 / 6 in plains and 1 / 4 in mountainous areas, and P I is the probability of a lightning current greater than I, η is the arcing rate, η=0.4, N g is the density of ground lightning in each area of ​​the terrain to be evaluated, b is the distance between two lightning conductors, and h is the height of the lightning conductor above the ground; The calculation formula for the shielding failure trip rate is obtained based on the cloud-to-ground flash density and lightning observation data in each area of the terrain to be evaluated as shown below: f(I)=I max (0.1r max ) 1.54 (10) Where P r is the interruption tripping rate, η is the arcing rate, η=0.4, ΔL is the collector line section with a length of ΔL, N g is the density of ground-to-ground lightning in each area of ​​the terrain to be evaluated, I max is the maximum current amplitude of the flashover, l BD is the lightning exposure width, f(I) is the lightning current probability density function, r max is the maximum impact distance; The calculation formula for the induced lightning trip rate is obtained based on the cloud-to-ground flash density and lightning observation data in each area of the terrain to be evaluated as shown below: y max =25H C I / U 50％ (12) Where P g is the induced lightning trip rate, D k is the distance from the direct hit point to the line, r c is the conductor striking distance, r g is the earth strike distance, H c y is the distance between the tower conductor suspension point and the ground, max is the flashover range of induced lightning, I is the induced lightning current, U 50％ Insulator string 50% impulse flashover voltage, N g is the density of ground-to-ground lightning in each area of ​​the terrain to be evaluated, η is the arcing rate, η=0.4, I C is the lightning current amplitude, P(I) is the lightning current amplitude distribution probability function; The calculation formula for the lightning trip rate of transmission lines in each area of the terrain to be evaluated is obtained based on the back flashover trip rate, shielding failure trip rate, and induced lightning trip rate as follows: In the formula, S is the average value of the lightning trip rates of each tower of the transmission lines in each area of the terrain to be evaluated, T is the total number of towers of the entire transmission line, m is the theoretically calculated lightning trip rate of the tower, m is the sum of the back flashover trip rate, shielding failure trip rate, and induced lightning trip rate, and n is the tower base number.

7. The power transmission line lightning risk assessment system according to claim 6, characterized in that: The specific method for evaluating the lightning strike risk of each area of the terrain to be evaluated through the lightning trip rate of the transmission line is as follows: When m < 0.5S, it is considered that the lightning strike risk level of the towers in each area of the terrain to be evaluated is Class I; When 0.5S < m < S, it is considered that the lightning strike risk level of the towers in each area of the terrain to be evaluated is Class II; When S < m < 1.5S, it is considered that the lightning strike risk level of the towers in each area of the terrain to be evaluated is Class III; When m > 1.5S, it is considered that the lightning strike risk level of the towers in each area of the terrain to be evaluated is Class IV.

8. A method for assessing the risk of lightning strikes on power transmission lines, characterized in that: Including: Divide the mountain body and the flat area outside the critical area of the mountain body into several extraction sections, divide the boundary of the mesoscopic terrain according to the coefficient of variation of the cloud-to-ground flash density of the extraction sections, and divide the range from the boundary of the mesoscopic terrain to the vertex of the mountain body into the mesoscopic scale terrain; Establish a mesoscopic terrain lightning downward leader fractal development model based on the spatial electric field of the mesoscopic scale terrain. By performing simulation calculations on the mesoscopic terrain lightning downward leader fractal development model, obtain the mesoscopic terrain ground lightning strike distribution; Use the mesoscopic terrain ground lightning strike distribution as the cloud-to-ground flash density of each area of the terrain to be evaluated. Calculate the lightning trip rate of the transmission lines in each area of the terrain to be evaluated based on the cloud-to-ground flash density and lightning observation data in each area of the terrain to be evaluated, and evaluate the lightning strike risk of each area of the terrain to be evaluated through the lightning trip rate of the transmission line.

9. The method for assessing the risk of lightning strike on a power transmission line according to claim 8, characterized in that: The specific method for dividing the mountain and the flat area outside the critical area of ​​the mountain into several extraction segments is: using the three-dimensional space formed by the width of the mountain, the height of the mountain, and the flat area from the mountain to the critical area of ​​the mountain as the research space for mesoscopic terrain scale division, and dividing the research space along the extraction direction from the flat area to the mountain area into several extraction segments with the same distance in the extraction direction.

10. The method for assessing the risk of lightning strike on a power transmission line according to claim 9, characterized in that: The specific method for dividing the boundary of the mesoscopic terrain according to the ground-to-ground lightning density variation coefficient of the extracted section and the average ground-to-ground lightning density variation coefficient of the flat area is: respectively calculate the ground-to-ground lightning density variation coefficients of several of the extracted sections, and compare the ground-to-ground lightning density variation coefficients of the several extracted sections obtained with the average ground-to-ground lightning density variation coefficient of the flat area in the study space; if the ground-to-ground lightning density variation coefficient of the extracted section is greater than the ground-to-ground lightning density variation coefficient of the flat area, then the extracted section is the critical section of the mesoscopic terrain scale in the study space, and the midpoint of the critical section is taken as the boundary of the mesoscopic terrain.

11. The method for assessing the risk of lightning strike on a power transmission line according to claim 10, characterized in that: The specific method of establishing the fractal development model of the downward leader of lightning in mesoscopic terrain according to the spatial electric field of the mesoscopic terrain is: dividing the mesoscopic terrain into a grid with discrete grid points of equal spacing, and the potential relationship of the spatial electric field formed by each discrete grid point in the grid is shown in the following formula: In the formula, is the potential of the grid point at the i-th row and j-th column in the grid, is the potential of the grid point at the i+1th row and jth column in the grid, is the potential of the grid point at the i-th row and j+1-th column in the grid, is the potential of the grid point at the i-th row and j-1-th column in the grid, is the potential of the grid point at the i-1th row and jth column in the grid; Formula (1) is calculated by super-relaxation iteration method, and the potential relationship of the spatial electric field of the grid after iteration is shown as follows: In the formula, After the nth iteration The value of ω is the relaxation factor, After the n+1th iteration The value of After the n+1th iteration The value of After the n+1th iteration The value of After the n+1th iteration The value of After the n+1th iteration The value of The calculation formula of the optimal relaxation factor that makes the iterative process converge fastest in formula (2) is as follows: Where ω0 is the optimal relaxation factor, n and m are the number of grids divided by the length and width of the rectangular area of ​​the mesoscopic terrain, respectively; The potential development point of the lightning downward leader is determined according to the discharge grid points inside the lightning discharge channel in the mesoscopic terrain. The determination formula is as follows: Where E is the average field strength between the discharge grid point inside the lightning discharge channel and the potential development point of the lightning leader. is the potential difference between the discharge grid point inside the lightning discharge channel and the potential development point of the downward leader of the lightning, L is the actual distance between the discharge grid point inside the lightning discharge channel and the potential development point of the downward leader of the lightning, E c is the critical discharge field strength, E c =216kV / m; The probability of the development of the potential development point of the downward leader of lightning is as follows: In the formula, The discharge grid point N inside the lightning discharge channel develops to the potential development point N of the lightning downward leader * The probability of The distance from the discharge grid point N inside the lightning discharge channel to the potential development point N of the lightning downward leader * The electric field strength between them, η is the development probability index, E c is the critical discharge field strength, E c =216kV / m; The potential development point of the downward leader of lightning develops into a discharge grid point inside a new lightning discharge channel. The potential calculation formula of the potential development point of the downward leader of lightning is as follows: In the formula, The potential development point N of the lightning leader that develops into a new lightning discharge channel * The potential, is the potential of the discharge grid point N inside the lightning discharge channel, E ch is the electric field strength inside the new lightning discharge channel, From the discharge grid point N to the potential development point N * The distance between.

12. The method for assessing the risk of lightning strike on a power transmission line according to claim 11, characterized in that: The specific method of simulating and calculating the mesoscopic terrain lightning downward leader fractal development model to obtain the mesoscopic terrain ground lightning distribution is as follows: calculating the potential and electric field strength of each grid point in the mesoscopic terrain, and continuously calculating the position and potential of the potential development point of the lightning downward leader through the mesoscopic terrain lightning downward leader fractal development model. When the potential development point of the lightning downward leader undergoes a jump change, the simulation of a lightning strike process is completed, and the above process is repeated until the simulation of t lightning strike processes is completed, and the coordinates of all lightning strike points are recorded to obtain the mesoscopic terrain ground lightning distribution.

13. The method for assessing the risk of lightning strike on a power transmission line according to claim 12, characterized in that: The specific method for calculating the lightning trip rate of the transmission line in each area of ​​the terrain to be evaluated based on the lightning density and lightning observation data in each area of ​​the terrain to be evaluated is as follows: The calculation formula for the strike-back trip rate is obtained based on the lightning density and lightning observation data in each area of ​​the terrain to be evaluated: P f =N×g×P I ×η (7) Where P f is the strike tripping rate, N is the total number of annual lightning strikes in the divided mesoscopic terrain, g is the pole striking rate, which is 1 / 6 in plains and 1 / 4 in mountainous areas, and P I is the probability of a lightning current greater than I, η is the arcing rate, η=0.4, N g is the density of ground lightning in each area of ​​the terrain to be evaluated, b is the distance between two lightning conductors, and h is the height of the lightning conductor above the ground; The calculation formula for the shielding failure trip rate is obtained based on the lightning density and lightning observation data in each area of ​​the terrain to be evaluated as follows: f(I)=I max (0.1r max ) 1.54 (10) Where P r is the interruption tripping rate, η is the arcing rate, η=0.4, ΔL is the collector line section with a length of ΔL, N g is the density of ground-to-ground lightning in each area of ​​the terrain to be evaluated, I max is the maximum current amplitude of the shielding flashover, I C is the lightning current amplitude, l BD is the lightning exposure width, f(I) is the lightning current probability density function, r max is the maximum impact distance; The calculation formula for the induced lightning trip rate is obtained based on the cloud-to-ground lightning density and lightning observation data of each region of the terrain to be evaluated as follows: y max =25H C I / U 50％ (12) Where P g is the induced lightning trip rate, D k is the distance from the direct hit point to the line, r c is the conductor striking distance, r g is the earth strike distance, H c y is the distance between the tower conductor suspension point and the ground, max is the flashover range of induced lightning, I is the induced lightning current, U 50％ Insulator string 50% impulse flashover voltage, N g is the density of ground-to-ground lightning in each area of ​​the terrain to be evaluated, η is the arcing rate, η=0.4, I C is the lightning current amplitude, P(I) is the lightning current amplitude distribution probability function; Based on the back-strike trip rate, shielding failure trip rate, and induced lightning trip rate, the calculation formula for the lightning trip rate of the transmission line in each region of the terrain to be evaluated is as follows: Wherein, S is the average value of the lightning trip rates of each tower of the transmission line in each region of the terrain to be evaluated, T is the total number of towers of the entire transmission line, m is the theoretically calculated lightning trip rate of the tower, m is the sum of the back-strike trip rate, shielding failure trip rate, and induced lightning trip rate, and n is the number of tower bases.

14. The method for assessing the risk of lightning strike on a power transmission line according to claim 13, characterized in that: The specific method for evaluating the lightning risk of each region of the terrain to be evaluated through the lightning trip rate of the transmission line is as follows: When m < 0.5S, it is considered that the lightning risk level of the towers in each region of the terrain to be evaluated is Class I; When 0.5S < m < S, it is considered that the lightning risk level of the towers in each region of the terrain to be evaluated is Class II; When S < m < 1.5S, it is considered that the lightning risk level of the towers in each region of the terrain to be evaluated is Class III; When m > 1.5S, it is considered that the lightning risk level of the towers in each region of the terrain to be evaluated is Class IV.

15. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, it implements the steps of the method described in any one of claims 8-14.

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