Lightning protection performance analysis system and method of dense power transmission channel considering shielding effect

Abstract

The application discloses a lightning protection performance analysis system and method of dense power transmission channel considering shielding effect, which comprises a dense channel generation module, a risk parameter statistics module, a channel parameter extraction module, a lightning protection performance analysis module and a tripping risk grade acquisition module, searches and generates a dense power transmission channel, counts lightning stroke risk source parameters of the dense power transmission channel, extracts tower structure parameters of lines in the dense power transmission channel, establishes a lightning protection performance analysis model of the dense power transmission channel considering shielding effect between lines, calculates lightning stroke tripping rates of the lines in the dense power transmission channel, and obtains lightning disaster risk grades of each tower foundation. The application can calculate lightning stroke tripping rates of the lines in the channel considering shielding effect, and obtain lightning disaster risk grades of each tower foundation, thereby providing more accurate and effective guidance for lightning disaster risk assessment and lightning protection measure reconstruction work of the dense channel lines.

Description

Technical Field

[0001] This invention belongs to the field of power grid lightning protection technology, and relates to a lightning protection performance analysis system and method for dense power transmission channels that takes into account the shielding effect. Background Technology

[0002] For a long time, lightning strikes have been the primary cause of power transmission line tripping. In State Grid Corporation of China's 500kV and above overhead lines, lightning strikes account for 40-60% of tripping incidents, seriously affecting the safe and stable operation of the power grid. For transmission lines at voltage levels above 500kV, since their backflashover withstand levels have already reached high values, the main cause of tripping accidents is backflashover current. Due to the contradiction between power transmission demand and land resource shortages, the emergence of dense transmission corridors has become unavoidable. Moreover, most of these dense transmission corridors are important ultra-high voltage transmission lines above 500kV, requiring safety assessments to ensure their stable operation. Therefore, the assessment of backflashover withstand performance of dense transmission corridors is extremely important.

[0003] Current analysis of lightning protection performance for power grids generally only considers single or multi-circuit transmission lines on the same tower, neglecting the issue of line shielding characteristics in dense transmission corridors composed of multiple lines. At the computational level, the leader development method offers higher accuracy than other methods, taking into account the physical process of lightning strikes; however, it also has more stringent parameter requirements. For complex conditions like dense transmission corridors, obtaining the parameters for the leader development method presents inherent difficulties, making the leader model method unsuitable.

[0004] Based on the above considerations, this invention proposes a method for searching and generating dense transmission channels. It statistically analyzes lightning risk source parameters such as ground flash density and lightning current amplitude within the dense transmission channels, extracts parameters such as the ground tilt angle of the lines and the tower structure within the channels, establishes a lightning resistance performance analysis model for dense transmission channels that considers the shielding effect between lines, calculates the lightning trip rate of the lines within the channels, obtains the lightning damage risk level for each tower, and systematizes this method to develop a dense transmission channel lightning damage risk assessment system. This provides more accurate and effective guidance for lightning damage risk assessment and lightning protection measure upgrades for dense transmission channel lines. Summary of the Invention

[0005] The purpose of this invention is to provide a lightning protection performance analysis system and method for dense power transmission channels that takes into account the shielding effect. An improved electrical geometric model method is proposed, which takes into account factors such as ground tilt angle and mutual shielding between lines. Its accuracy is verified by comparison with traditional methods.

[0006] To achieve this objective, the present invention designs a lightning protection performance analysis system for dense transmission channels that considers the shielding effect, comprising a dense channel generation module, a risk parameter statistics module, a channel parameter extraction module, a lightning withstand performance analysis module, and a tripping risk level acquisition module. The dense channel generation module is used to search for and generate dense transmission channels. The risk parameter statistics module is used to statistically analyze the lightning risk source parameters of the dense transmission channels generated by the dense channel generation module. The channel parameter extraction module is used to extract the tower structure parameters of the lines within the dense transmission channels generated by the dense channel generation module. The lightning withstand performance analysis module is used to establish a lightning withstand performance analysis model for dense transmission channels that considers the inter-line shielding effect. The tripping risk level acquisition module calculates the lightning tripping rate of the lines within the dense transmission channels generated by the dense channel generation module, the lightning risk source parameters obtained by the risk parameter statistics module, the tower structure parameters generated by the channel parameter extraction module, and the inter-line shielding coefficient extracted by the lightning withstand performance analysis module, thereby obtaining the lightning damage risk level for each tower.

[0007] A method for analyzing the lightning protection performance of dense power transmission channels considering the shielding effect, comprising the following steps:

[0008] Step 1: Search for and generate dense power transmission channels;

[0009] Step 2: Statistically analyze the lightning strike risk source parameters of the dense power transmission channels generated in Step 1;

[0010] Step 3: Extract the tower structure parameters of the lines within the dense power transmission channel generated in Step 1;

[0011] Step 4: Establish a lightning withstand performance analysis model for dense transmission channels that takes into account the shielding effect between lines;

[0012] Step 5: Based on the dense power transmission channel generated in Step 1, the lightning risk source parameters obtained in Step 2, the tower structure parameters generated in Step 3, and the line shielding coefficient extracted in Step 4, calculate the line lightning trip rate in the dense power transmission channel to obtain the lightning damage risk level of each tower.

[0013] The beneficial effects of this invention are as follows: This invention can calculate the lightning trip rate of lines in the channel after considering the shielding effect, and obtain the lightning damage risk level of each tower, providing more accurate and effective guidance for the lightning damage risk assessment and lightning protection measure renovation of densely packed lines. Attached Figure Description

[0014] Figure 1 This is a system structure diagram of the present invention;

[0015] Figure 2 This is a flowchart of the method of the present invention;

[0016] Figure 3 Example diagram of composite channel search;

[0017] Figure 4 A graph of lightning parameters obtained using the grid method;

[0018] Figure 5 To extract 3D schematic diagrams for refined terrain parameters;

[0019] Figure 6 A schematic diagram of the extracted topographic data;

[0020] Figure 7 Diagram for determining the sign of ground tilt angle;

[0021] Figure 8 This is a schematic diagram of ground tilt transformation;

[0022] Figure 9 The result is a graph showing the tripping rate after the circuit breaker trips.

[0023] Figure 10 This is a schematic diagram for assessing the risk of lightning damage to power lines (without considering shielding).

[0024] Figure 11 This is a schematic diagram for assessing the risk of lightning damage to power lines (with shielding considered).

[0025] Figure 12 This is the interface (parameter input) for the dense corridor lightning hazard risk assessment system.

[0026] Figure 13 This is the interface for a dense channel lightning damage risk assessment system (channel lightning protection performance calculation);

[0027] Among them, 1-Dense channel generation module, 2-Risk parameter statistics module, 3-Channel parameter extraction module, 4-Lightning resistance performance analysis module, and 5-Tripping risk level acquisition module. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0029] A lightning protection performance analysis system for dense power transmission channels that takes into account the shielding effect, such as Figures 1-13 As shown, it includes a dense channel generation module 1, a risk parameter statistics module 2, a channel parameter extraction module 3, a lightning resistance performance analysis module 4, and a tripping risk level acquisition module 5.

[0030] The dense channel generation module 1 is used to search for and generate dense power transmission channels;

[0031] The risk parameter statistics module 2 is used to count the lightning risk source parameters of the dense power transmission channels generated by the dense channel generation module 1;

[0032] The channel parameter extraction module 3 is used to extract the tower structure parameters of the lines in the dense power transmission channels generated by the dense channel generation module 1;

[0033] The lightning resistance performance analysis module 4 is used to establish a lightning resistance performance analysis model for dense transmission channels that takes into account the shielding effect between lines.

[0034] The tripping risk level acquisition module 5 calculates the line lightning tripping rate within the dense transmission channels generated by the dense channel generation module 1, the lightning risk source parameters obtained by the risk parameter statistics module 2, the tower structure parameters generated by the channel parameter extraction module 3, and the line shielding coefficient extracted by the lightning resistance performance analysis module 4, and obtains the lightning damage risk level of each tower.

[0035] In the above technical solution, the specific implementation of the dense channel generation module 1 is as follows:

[0036] The transmission line corridor is defined as a line element buffer zone, that is, the axis L of the transmission line corridor is {P1,…,P}. N+1 The polygon B(L,R) is formed by translating the axis to both sides along the normal direction of the axis by a buffer distance R, and connecting the endpoints of the axis with semicircular arcs, and satisfies the following formula:

[0037] B(L,R)={T|{d(T,L i )|L i ∈L}≤R}

[0038] In the formula, B(L,R) represents the buffer zone of the line element L with a buffer distance of R, where L... i Let d(T,L) represent the i-th line segment on a given line feature, R represent the buffer distance, T represent any point within the buffer zone B(L,R), and d(T,L) represent the line segment on the given line feature. i ) represents the buffer distance R and the i-th shortest line segment L on the given line element. i The distance;

[0039] Using the "birdseye" approach, the overlapping portions of the line element buffer zones formed by multiple transmission line corridors in the dense transmission channel are identified, and then the relationship between transmission lines and transmission towers is matched in the overlapping portions.

[0040] In the above technical solution, the specific method for matching the relationship between the transmission line and the transmission tower in the overlapping part is as follows:

[0041] Step 11: Using the line element formed by a single transmission line corridor in the dense transmission channel as a reference, delineate the portion of the line element buffer that overlaps with other transmission line corridors.

[0042] Step 12: For each transmission line corridor in the dense transmission channel, perform step 11 to obtain the set of line segments that make up the dense transmission channel;

[0043] Step 13: For the set of line segments formed in Step 12, find the secondary composite channel formed by the convergence of two transmission line corridors to generate a candidate set of two-line composite channels. At this time, it includes a proper subset of higher-level channels formed by the convergence of more transmission line corridors. Then, find the tertiary composite channel formed by the convergence of three transmission line corridors to generate a candidate set of three-line composite channels. For the candidate set of three-line composite channels, find the overlapping secondary composite channels that contain the same transmission line corridor as the tertiary composite channels. Delete the overlapping secondary composite channels from the candidate set of two-line composite channels to obtain a set of two-line composite channels. Following this approach, find a higher-level multi-line composite channel set until no more are found.

[0044] The conditions for the convergence of transmission line corridors are not fixed and can be flexibly formulated according to the line voltage level, length, etc. According to the State Council General Office Letter

[2022] No. 50, if there are other lines (or some sections of them) within a 600m corridor radius of a line, it can be regarded as the convergence of two line corridors.

[0045] by Figure 3 Taking the left line as a reference, two sets of two-line channels (a,b) and (a,c) are generated. Using the middle line as a reference, three sets of two-line channels (a,b), (b,c), and (e,d) are generated. Finally, using the right line as a reference, three sets of two-line channels (a,c), (b,c), and (d,e) are generated. That is, there are four sets of two-line channels among these three lines: (a,b), (b,c), (a,c), and (d,e). Among these, the three sets (a,b), (b,c), and (a,c) are mutually two-line channels, so it can be determined that (a,b,c) can form a three-line channel. At this point, there are not enough three-line channels to form a four-line channel, and the search stops. Using a similar idea, the recursive search process stops when the channels formed by n lines no longer have lower-level channels to support them.

[0046] In the above technical solution, the lightning risk source parameters obtained by the risk parameter statistics module 2 include ground flash density and lightning current amplitude;

[0047] The specific implementation method for the risk parameter statistics module 2 to obtain the ground flash density is as follows: the ground flash density distribution parameters are statistically analyzed using a grid method, such as... Figure 4As shown, the dense power transmission corridor generated by the dense channel generation module 1 is divided into a series of grids with approximately equal areas. The ground flash density in each grid is counted. The ground flash density in each grid is the ground flash density that makes up the dense channel corridor area. The ground flash density value of each area is obtained by using a weighted average calculation method to form a ground flash density distribution.

[0048] The area to be analyzed is divided into n grids of equal latitude and longitude, and the area of ​​each grid is denoted as S1, S2, ..., S... n Total grid area S a =S1+S2+…+S n The number of ground flashes in each grid is denoted as N1, N2, ..., N. n , N1+N2+…+N n =N a The average value N of the ground flash density g It can be represented as

[0049]

[0050] In the formula, N g The value is the average ground flash density, where n is the number of grid cells, i is the grid number, and N is the average ground flash density. gi S is the average ground flash density of the i-th grid. i Let N be the area of ​​the i-th grid. i S represents the number of ground flashes within the i-th grid. a N represents the total area of ​​the grid. a This represents the total number of ground flashes within the grid.

[0051] The specific implementation method of the risk parameter statistics module 2 to obtain the lightning current amplitude is as follows: Lightning flashes within the area where the dense transmission channel corridor generated by the dense channel generation module 1 is located are obtained, and the lightning current amplitudes are statistically analyzed at intervals of ΔI to obtain (0,ΔI], (ΔI,2ΔI], ..., (I...). m -ΔI,I m ]、(I m ,∞)(I m The number of ground flashes in each interval (preferably an integer multiple of ΔI) are N0, N1, ..., N n-1 N n Calculate the lightning current amplitude I, taking values ​​of 0, ΔI, ..., I. m –ΔI、I m The value of P(>I) represents the probability that the lightning current amplitude is greater than I, yielding discrete points (0, P(>0)), (ΔI, P(>ΔI))...(I). m –ΔI,P(>I m –ΔI)), (I m ,P(>I m )):

[0052]

[0053] In the formula, P(>I) is the probability that the lightning current amplitude is greater than I, k is the ratio of the lightning current amplitude to the statistical interval of the lightning current amplitude, ΔI is the statistical interval (step size) of the lightning current amplitude, I is the lightning current amplitude, j is the ground flash ordinal number, and N j N represents the total number of ground flashes. k The number of lightning flashes with a lightning current amplitude greater than I during lightning-to-ground flashes;

[0054] Using the recommended expression in IEEE Std 1234—1997 as a prototype, curve fitting is performed on the discrete points to obtain the fitted values ​​of parameters a and b, thus obtaining the fitted expression. The recommended expression is:

[0055]

[0056] In the formula, P(>I) is the probability that the lightning current amplitude is greater than I, I is the lightning current amplitude, a is the median lightning current, and b is the amplitude distribution concentration parameter. The fitting expression is the cumulative probability distribution of the lightning current amplitude in the dense channel corridor. Generally, I can be selected. m =400, ΔI=2.

[0057] In the above technical solution, the tower structure parameters extracted by the channel parameter extraction module 3 include ground tilt angle, tower structure, phase conductor height, phase conductor center distance, ground wire height, center distance, and insulator string dry arc distance.

[0058] In the above technical solution, the specific implementation of the channel parameter extraction module 3 is as follows:

[0059] Using technologies such as laser point cloud and intelligent image recognition, the transmission lines and their surrounding topography in the dense transmission channel generated by the dense channel generation module 1 are scanned, and the original data of important power facilities and their surrounding environment are collected to generate a three-dimensional model of each tower in the dense transmission channel generated by the dense channel generation module 1.

[0060] Using methods such as clustering and semantic segmentation, the key parameters of important power facilities are extracted from the coordinates of the conductors and ground wires in the three-dimensional space of the dense power transmission channel generated by the dense channel generation module 1, thereby achieving the separation of key parameters of the power facilities. The key parameters of the important power facilities include the phase conductor height, the phase conductor center distance, the ground wire height, the center distance, and the dry arc distance of the insulator string.

[0061] The ground tilt angle of each base tower in the dense power transmission channel generated by the dense channel generation module 1 is calculated in detail using the weighted average method.

[0062] In the above technical solution, the specific implementation method of the channel parameter extraction module 3 for fine calculation of the tower ground tilt angle is as follows:

[0063] Given the latitude and longitude coordinates of each tower, the altitude of the tower location can be directly extracted from publicly available data. However, topographic parameters cannot be directly obtained. This paper, under the premise of meeting the requirements of full-span flashover risk assessment, performs a refined extraction of the ground inclination angle. The specific method is as follows: Select a transmission line from the dense transmission channels generated by the dense channel generation module 1. Take any point O on the ground at the center of the span of the selected transmission line. Draw a rectangular cross-section perpendicular to the direction of the selected transmission line through point O. The rectangular cross-section intersects the ground to form an intersection line. With point O as the center, take m points on each side of the intersection line, where the distance d between any two points is equal. Calculate the ground inclination angle θ of each point relative to the tower. j (j = 1, 2, ..., m), see Figure 5 and Figure 6 After obtaining the ground tilt angle value, analyze the sign of the ground tilt angle value; the sign of the ground tilt angle is defined as follows: Figure 7 As shown, h1 and h2 are both altitudes, and θ is the ground inclination angle of h2 relative to h1. Figure 7 a) shows the case where the ground tilt angle is positive. In this case, according to the EGM model, the ground shielding effect is weakened, and the probability of the channel section being hit by a backlash increases. Conversely, when the ground tilt angle is negative, the ground shielding effect is enhanced, and the probability of the channel section being hit by a backlash decreases. Therefore, it is necessary to consider both positive and negative values.

[0064] When using the Electrical Geometric Model (EGM model) for calculations, since only one value can be used to describe the influence of the ground tilt angle, the final formula for calculating the ground tilt angle θ is:

[0065]

[0066] In the formula, θ is the ground inclination angle, m is the number of points selected on both sides of the tower along a direction perpendicular to the line direction, j is the ordinal number of the ground inclination angle, and θ j Let j be the ground inclination angle;

[0067] The method for selecting a transmission line in the dense transmission channel generated by the dense channel generation module 1 is as follows: if the number of transmission lines in the dense transmission channel is ≥3, then the transmission line in the middle of the horizontal position is selected; if the number of transmission lines in the dense transmission channel is <3, then any transmission line is selected.

[0068] In the above technical solution, the specific implementation method of the lightning resistance performance analysis module 4 is as follows: establish a lightning resistance performance analysis model for dense transmission channels that takes into account the shielding effect between lines;

[0069] Determining the exposed arc projection length is a necessary step in calculating the tripping rate using EGM. Previously, only the exposed arc projection length of a single transmission line needed to be calculated. This patent requires calculating the exposed arc projection considering the shielding effect of adjacent lines, making conventional methods no longer applicable. Therefore, this patent optimizes the projection calculation method, automatically calculating the exposed arc projection, and is applicable to various complex operating conditions under both single-channel and multi-channel conditions. The specific implementation method for automatically calculating the exposed arc projection is as follows:

[0070] The concept of anchor point towers is introduced, and these anchor point towers are used as the origin of the coordinate axes of the overall model for subsequent transformations, such as... Figure 8 As shown, the tower on the left is the anchor tower. By inputting the distance and height difference parameters between subsequent towers and the anchor tower, the coordinate axis of each subsequent tower relative to the intersection of the anchor tower and the ground is transformed into a new coordinate axis relative to the intersection of the subsequent tower and the ground. Using the new coordinates, the conductor and ground wire striking distances of the subsequent towers are compared with the ground striking distance to obtain the final exposed arc projection result.

[0071] y′=-xsinθ+ycosθ+Ssinθ-hcosθ

[0072] In the formula, x is the abscissa of the subsequent tower in the original coordinate system, y is the ordinate of the subsequent tower in the original coordinate system, S is the distance between the subsequent tower and the anchor tower, h is the height difference between the subsequent tower and the anchor tower, θ is the ground inclination angle, and y' is the ordinate of the subsequent tower in the new coordinate system.

[0073] To reflect the impact of various factors in densely populated corridors on the tripping rate of each line, this invention introduces the concept of a shielding coefficient, which is calculated using the following formula:

[0074]

[0075] The value ranges from 0 to 1. The closer the result is to 1, the stronger the shielding effect. After calculation for a typical channel, it was found that the shielding factor is about 1 at the calculation result with a tower spacing of 250m, which is equivalent to complete shielding.

[0076] In the above technical solution, when calculating the lightning trip rate of transmission lines in the dense transmission channel, the trip risk level acquisition module 5 selects actual parameters from real transmission line projects for calculation, such as... Figure 12-13 As shown.

[0077] The target line has a total of 811 towers, of which 564 have fewer than 3 parallel circuits. There are 151 towers with 3 parallel circuits, 54 with 4 parallel circuits, and 42 with 5 parallel circuits. Taking a specific tower from this line as an example, the calculation results are as follows... Figure 9 Considering shielding, except for the left-hand line of the leftmost tower which is unaffected by adjacent lines, all other lines are protected by nearby lightning protection wires, and the simulation results for their tripping rate due to lightning strikes remain at a very low value. Therefore, the parallel lines can be considered safe. Figure 10 and Figure 11 The data distribution shown primarily illustrates the tripping rate calculation results with and without considering the shielding effect of adjacent lines. The target line is an ±800kV line. According to regulations, its basic lightning tripping rate design requirement is 0.1 times / (100km·a), corresponding to 0.15 and 0.3 for transmission risk levels 3 and 4, respectively. Based on the above classification, the number of towers in the three categories without considering shielding is 210, 381, and 220 respectively. Considering the shielding effect of adjacent lines, the number of towers in the three categories is 34, 77, and 700 respectively. It can be seen that after considering the shielding effect of adjacent lines, the tripping rate of the transmission line decreases to a certain extent, and the number of high-risk towers decreases significantly, indicating that the shielding effect is indispensable for the lightning protection design level of dense transmission lines.

[0078] Based on the above analysis of results from actual engineering projects, the calculation method proposed in this invention can be applied to the calculation of power transmission line tripping rates in actual engineering projects, providing a reference for the study of lightning protection levels of power transmission lines.

[0079] A method for analyzing the lightning protection performance of dense power transmission channels considering shielding effects, characterized by comprising the following steps:

[0080] Step 1: Search for and generate dense power transmission channels;

[0081] Step 2: Statistically analyze the lightning strike risk source parameters of the dense power transmission channels generated in Step 1;

[0082] Step 3: Extract the tower structure parameters of the lines within the dense power transmission channel generated in Step 1;

[0083] Step 4: Establish a lightning withstand performance analysis model for dense transmission channels that takes into account the shielding effect between lines;

[0084] Step 5: Based on the dense power transmission channel generated in Step 1, the lightning risk source parameters obtained in Step 2, the tower structure parameters generated in Step 3, and the line shielding coefficient extracted in Step 4, calculate the line lightning trip rate in the dense power transmission channel to obtain the lightning damage risk level of each tower.

[0085] The contents not described in detail in this specification are prior art known to those skilled in the art. Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied 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.

[0086] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0087] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0088] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit its scope of protection. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading the present invention, they can still make various changes, modifications or equivalent substitutions to the specific implementation of the invention, but these changes, modifications or equivalent substitutions are all within the scope of protection of the pending claims of the invention.

Claims

1. A lightning protection performance analysis system for dense power transmission channels taking into account the shielding effect, characterized in that: include: The dense channel generation module is used to search for and generate dense power transmission channels; The risk parameter statistics module is used to statistically analyze the lightning risk source parameters of the dense transmission channels generated by the dense channel generation module; The channel parameter extraction module is used to extract the tower structure parameters of the lines in the dense transmission channels generated by the dense channel generation module; The lightning withstand performance analysis module is used to establish a lightning withstand performance analysis model for dense transmission channels that takes into account the shielding effect between lines, and to calculate the shielding coefficient between lines; The tripping risk level acquisition module calculates the line lightning tripping rate within the dense transmission channels generated by the dense channel generation module, the lightning risk source parameters obtained by the risk parameter statistics module, the tower structure parameters generated by the channel parameter extraction module, and the line shielding coefficient extracted by the lightning resistance performance analysis module, and obtains the lightning damage risk level of each tower. The specific implementation method of the channel parameter extraction module is as follows: The scanning module generates a 3D model of each tower in the dense power transmission channel generated by the dense channel generation module. The key parameters of important power facilities are extracted from the coordinates of the conductors and ground wires in the three-dimensional space of the dense power transmission channel generated by the dense channel generation module, so as to realize the separation of key parameters of the power facilities. The key parameters of important power facilities include phase conductor height, phase conductor center distance, ground wire height, center distance, and dry arc distance of insulator string. The ground tilt angle of each base tower in the dense power transmission channel generated by the dense channel generation module is calculated in detail.

2. The lightning protection performance analysis system for dense power transmission channels taking into account the shielding effect as described in claim 1, characterized in that: The specific implementation method of the dense channel generation module is as follows: The transmission line corridor is defined as a line element buffer zone. The axis L={P1,…,PN+1} of the transmission line corridor is translated to both sides along the normal direction of the axis by a buffer distance R. The polygon B(L, R) formed by connecting the endpoints of the axis with semicircular arcs satisfies the following formula: In the formula, B(L, R) represents the buffer zone of line element L with buffer distance R, Li represents the i-th line segment on the given line element, R represents the buffer distance, T represents any point within the buffer zone B(L, R), and d(T, Li) represents the distance between the buffer distance R and the i-th short line segment Li on the given line element. Using the shotgun approach, the overlapping portions of the line element buffer zones formed by multiple transmission line corridors in the dense transmission channel are identified, and then the relationship between transmission lines and transmission towers is matched in the overlapping portions.

3. The lightning protection performance analysis system for dense power transmission channels taking into account the shielding effect as described in claim 2, characterized in that: The specific method for matching the relationship between transmission lines and transmission towers in the overlapping portion is as follows: Step 11: Using the line element formed by a single transmission line corridor in the dense transmission channel as a reference, delineate the portion of the line element buffer that overlaps with other transmission line corridors. Step 12: For each transmission line corridor in the dense transmission channel, perform step 11 to obtain the set of line segments that make up the dense transmission channel; Step 13: For the set of line segments formed in Step 12, generate a candidate set of two-line composite channels. At this time, it includes a proper subset of higher-level channels formed by the convergence of more transmission line corridors. Then, find a tertiary composite channel formed by the convergence of three transmission line corridors to generate a candidate set of three-line composite channels. For the candidate set of three-line composite channels, find overlapping secondary composite channels that contain the same transmission line corridors as the tertiary composite channels. Delete the overlapping secondary composite channels from the candidate set of two-line composite channels to obtain a set of two-line composite channels. Following this approach, search for a higher-level multi-line composite channel set until no more are found.

4. The lightning protection performance analysis system for dense power transmission channels taking into account the shielding effect as described in claim 1, characterized in that: The lightning risk source parameters obtained by the risk parameter statistics module include ground flash density and lightning current amplitude. The specific implementation method of the risk parameter statistics module to obtain the ground flash density is as follows: the ground flash density distribution parameters are statistically analyzed using the grid method. The dense transmission channel corridor generated by the dense channel generation module is divided into a series of grids with approximately equal areas. The ground flash density in each grid is statistically analyzed. The ground flash density in each grid is the ground flash density that makes up the dense transmission channel corridor area. The ground flash density value of each area is obtained by using the weighted average calculation method to form the ground flash density distribution. The area to be statistically analyzed is divided into n grids of equal latitude and longitude. The area of ​​each grid is denoted as S1, S2, ..., Sn, and the total area of ​​the grid is Sa = S1 + S2 + ... + Sn. The number of lightning strikes in each grid is denoted as N1, N2, ..., Nn, respectively, where N1 + N2 + ... + Nn = Na. Then, the average lightning strike density Ng can be expressed as... In the formula, Ng is the average ground flash density, n is the number of grids, i is the grid number, Ngi is the average ground flash density of the i-th grid, Si is the area of ​​the i-th grid, Ni is the number of ground flashes in the i-th grid, Sa is the total area of ​​the grid, and Na is the total number of ground flashes in the grid. The specific implementation method of the risk parameter statistics module to obtain the lightning current amplitude is as follows: Lightning flashes within the area where the dense transmission channel corridor generated by the dense channel generation module is located are obtained. The lightning current amplitude is statistically analyzed at intervals of ΔI, and the number of flashes in each interval (0, ΔI], (ΔI, 2ΔI]…, (Im-ΔI, Im], (Im, ∞) is obtained as N0, N1…, Nn-1, Nn. The value of P(>I) when the lightning current amplitude I takes the values ​​of 0, ΔI…, Im-ΔI, Im is the probability that the lightning current amplitude is greater than I, resulting in discrete points (0, P(>0)), (ΔI, P(>ΔI))…(Im-ΔI, P(>Im-ΔI)), (Im, P(>Im)). In the formula, P(>I) is the probability that the lightning current amplitude is greater than I, k is the ratio of the lightning current amplitude to the statistical interval of the lightning current amplitude, ΔI is the statistical interval of the lightning current amplitude, I is the lightning current amplitude, j is the ground flash ordinal number, Nj is the total number of ground flashes, and Nk is the number of ground flashes with a lightning current amplitude > I. Using the recommended expression in IEEE Std 1234-1997 as a prototype, curve fitting is performed on the discrete points to obtain the fitted values ​​of parameters a and b, thus obtaining the fitted expression. The recommended expression is: In the formula, P(>I) is the probability that the lightning current amplitude is greater than I, I is the lightning current amplitude, a is the median of the lightning current, and b is the parameter of the concentration of amplitude distribution. The fitting expression is the cumulative probability distribution of the lightning current amplitude in the dense transmission channel corridor.

5. The lightning protection performance analysis system for dense power transmission channels taking into account the shielding effect as described in claim 1, characterized in that: The tower structure parameters extracted by the channel parameter extraction module include ground tilt angle, tower structure, phase conductor height, phase conductor center distance, ground wire height, center distance, and insulator string dry arc distance.

6. The lightning protection performance analysis system for dense power transmission channels taking into account the shielding effect as described in claim 1, characterized in that: The specific implementation method of the channel parameter extraction module for fine calculation of the tower ground tilt angle is as follows: In the dense transmission channel generated by the dense channel generation module, select a transmission line. Take any point O on the ground at the center of the span of the selected transmission line. Draw a rectangular cross-section perpendicular to the direction of the selected transmission line through point O. This rectangular cross-section intersects the ground to form an intersection line. Using point O as the center, take m points on each side of this intersection line, where the distance d between any two points is equal. Calculate the ground inclination angle θ of each point relative to the tower. j , j=1,2, ……, m; After obtaining the ground tilt angle value, analyze the positive and negative signs of the ground tilt angle value; The formula for calculating the ground tilt angle θ is: In the formula, θ is the ground inclination angle, m is the number of points selected on both sides of the tower along the direction perpendicular to the line, j is the ordinal number of the ground inclination angle, and θj is the j-th ground inclination angle; The method for selecting a transmission line in the dense transmission channel generated by the dense channel generation module is as follows: if the number of transmission lines in the dense transmission channel is ≥3, then the transmission line in the middle of the horizontal position is selected; if the number of transmission lines in the dense transmission channel is <3, then any transmission line is selected.

7. The lightning protection performance analysis system for dense power transmission channels considering shielding effects according to claim 1, characterized in that: The specific implementation method of the lightning resistance performance analysis module is as follows: establish a lightning resistance performance analysis model for dense transmission channels that takes into account the shielding effect between lines; The specific implementation method for automatically calculating the projection of the exposure arc is as follows: The concept of anchor towers is introduced, and subsequent transformations are performed using the anchor towers as the origin of the coordinate axes of the overall model. By inputting the distance and height difference parameters between subsequent towers and the anchor towers, the coordinate axes of each subsequent tower relative to the intersection of the anchor tower and the ground are transformed into new coordinate axes relative to the intersection of the subsequent tower and the ground. These new coordinates are then used to compare the conductor and ground wire striking distances of the subsequent towers with the ground striking distance, resulting in the final exposed arc projection result. In the formula, x is the abscissa of the subsequent tower in the original coordinate system, y is the ordinate of the subsequent tower in the original coordinate system, S is the distance between the subsequent tower and the anchor tower, h is the height difference between the subsequent tower and the anchor tower, θ is the ground inclination angle, and y' is the ordinate of the subsequent tower in the new coordinate system. The concept of a shielding coefficient is introduced, and the formula for calculating the shielding coefficient is as follows: 。 8. The lightning protection performance analysis system for dense power transmission channels considering shielding effects according to claim 1, characterized in that: When calculating the lightning trip rate of transmission lines in the dense transmission channel, the trip risk level acquisition module selects actual parameters from real transmission line projects for calculation.

9. A method for analyzing the lightning protection performance of dense power transmission channels considering the shielding effect using the system described in claim 1, characterized in that, It includes the following steps: Step 1: Search for and generate dense power transmission channels; Step 2: Statistically analyze the lightning strike risk source parameters of the dense power transmission channels generated in Step 1; Step 3: Extract the tower structure parameters of the lines within the dense power transmission channel generated in Step 1; Step 4: Establish a lightning withstand performance analysis model for dense transmission channels that takes into account the shielding effect between lines, and calculate the shielding coefficient between lines; Step 5: Based on the dense power transmission channel generated in Step 1, the lightning risk source parameters obtained in Step 2, the tower structure parameters generated in Step 3, and the line shielding coefficient extracted in Step 4, calculate the line lightning trip rate in the dense power transmission channel to obtain the lightning damage risk level of each tower.

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