Method for identifying and quantitatively analyzing all lightning activity area facing kilometer-level grid

Abstract

The application discloses a method for identifying and quantitatively analyzing a full lightning activity area in a kilometer grid, and relates to the technical field of lightning monitoring and early warning, comprising the following steps: matching discrete full lightning data in a kilometer grid; identifying a primary lightning cluster based on an eight-ray radial grid; obtaining a terminal lightning cluster based on an edge radial grid; and quantitatively evaluating an index of a lightning activity area. Through two-stage combined lightning, the method can effectively identify lightning clusters in mature, dying and starting stages, reduce the number of lightning clusters in the mature stage, identify lightning activity areas in thunderstorm processes under different scale requirements, quantitatively evaluate different lightning cluster activity area identification results by using lightning cluster area, lightning cluster area proportion, number of lightning clusters in a time interval and lightning event utilization rate as quantification indexes of the lightning activity area, solve the problem of quantitatively comparing different algorithm identification results, and provide technical support for lightning monitoring under different scales.

Description

Technical Field

[0001] This invention relates to the field of lightning monitoring and early warning technology, specifically to a method for identifying and quantifying all-lightning activity areas on a kilometer-scale grid. Background Technology

[0002] Lightning strikes are the leading cause of tripping in ultra-high voltage (UHV) and extra-high voltage (EHV) transmission lines. These lines stretch for hundreds of kilometers, and power facilities along the routes, including towers, substations, and converter stations, are highly susceptible to lightning strikes. Compared to the regional severe convective weather forecasting services provided by meteorological departments, the power system, comprised of lines, towers, and substations, requires lightning activity monitoring and prediction accurate to the span level of transmission lines. Kilometer-level regional lightning activity monitoring can provide dedicated early warning systems at the station level, protecting vulnerable power electronic equipment, reducing unplanned outages caused by lightning strikes, and improving the reliability of the power system.

[0003] Lightning cluster identification is the first step in monitoring lightning activity trajectories, and its results play a crucial role in the monitoring outcomes and the description of lightning activity characteristics. Existing methods for identifying lightning activity areas mainly suffer from the following problems: Traditional lightning cluster identification methods are mostly based on clustering with a fixed neighborhood radius, making it difficult to simultaneously and effectively identify lightning clusters at different life stages of a thunderstorm (initial stage, development stage, mature stage, and dissipation stage). Mature stage thunderstorms have a large area and high lightning density, making them prone to being over-segmented into multiple lightning clusters, resulting in redundant cluster counts. In contrast, the initial and dissipation stages have small thunderstorm areas and sparse lightning, making them prone to being missed or incorrectly merged. Existing methods mostly focus on identifying ground-to-ground lightning data, lacking comprehensive utilization of all lightning data (cloud-to-ground lightning and ground-to-ground lightning), making it difficult to fully reflect the evolutionary patterns of thunderstorm processes. Furthermore, the identification results of different lightning cluster identification algorithms lack unified quantitative evaluation indicators, making it difficult to objectively compare the identification effects of different algorithms and parameter settings. Summary of the Invention

[0004] The purpose of this invention is to provide a method for identifying and quantifying all lightning activity areas on a kilometer-scale grid, in order to solve the problem that existing lightning cluster identification methods are mostly based on clustering with a fixed neighborhood radius, which makes it difficult to simultaneously and effectively identify lightning clusters at different life stages of a thunderstorm (initial stage, development stage, mature stage, and dissipation stage). Mature stage thunderstorms have a large range and high lightning density, which can easily be over-segmented into multiple lightning clusters, resulting in redundant numbers of lightning clusters. In contrast, the initial and dissipation stages have small thunderstorm ranges and sparse lightning, which can easily be missed or incorrectly merged.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for identifying and quantifying all-lightning activity areas on a kilometer-scale grid, comprising the following steps:

[0006] S1: Kilometer-scale grid matching of discrete full-lightning data;

[0007] S2: Primary lightning cluster identification based on an eight-ray radial grid;

[0008] S3: Acquisition of final lightning clusters based on edge radial grid;

[0009] S4: Quantitative assessment index of lightning activity area.

[0010] Furthermore, the kilometer-level grid matching of the discrete full lightning data in step S1 includes the following sub-steps:

[0011] S11: Within the rectangular area covered by the full-lightning positioning system, the geographical area of ​​the coverage area is gridded, and the grid size can be set as needed;

[0012] S12: Discrete total lightning data within the time interval Δt are assigned to a pre-defined grid according to geographic coordinates to obtain a total lightning density map.

[0013] Furthermore, the grid size can be set to a range of 0.01° to 0.05° as needed.

[0014] Furthermore, the time interval Δt ranges from 1 to 15 minutes.

[0015] Furthermore, the primary lightning cluster identification based on an eight-ray radial grid in step S2 includes the following sub-steps:

[0016] S21: The eight-ray radial grid refers to searching from a central grid containing all lightning data in eight directions: left, upper left, top, upper right, right, lower right, bottom, and lower left.

[0017] S22: If the eight-ray radial grid of the central grid described in S21 contains full lightning data, then use this grid as the new central grid and continue to search for the eight-ray radial grid of the new central grid until no new grid is found. All the grids found that contain full lightning data are classified into one category, namely, primary lightning clusters.

[0018] S23: The polygon fitting method is used to fit the primary lightning cluster to obtain the outline region of the primary lightning cluster.

[0019] Furthermore, the final lightning cluster acquisition based on the edge radial grid in step S3 includes the following sub-steps:

[0020] S31: Taking grid a in primary lightning cluster A as the center, find whether the grid containing full lightning data within the radial grid range (8, 24, 48, 80, 120, 168 neighborhoods) belongs to primary lightning cluster B;

[0021] S32: If it belongs to primary lightning cluster B, then the two primary lightning clusters merge to form a new final lightning cluster; otherwise, primary lightning cluster A directly forms a final lightning cluster.

[0022] S33: The polygon fitting method is used to fit the final lightning cluster to obtain the outline region of the final lightning cluster.

[0023] Furthermore, the quantitative evaluation index of lightning activity area in step S4 includes the following sub-steps:

[0024] S41: Use the area of ​​the polygon-fitted region as the area S of the lightning cluster. c :

[0025]

[0026] in, N represents the area of ​​a single grid cell, and N is the number of grid cells covered by the lightning cluster.

[0027] S42: The centroid of the lightning cluster is the centroid of the fitted polygon.

[0028]

[0029] in,( ( ) represents the coordinates of each vertex of the fitted polygon. The number of vertices;

[0030] S43: Number of final lightning clusters N, total lightning event utilization rate within time interval Δt The percentage of total lightning events that participate in the formation of a lightning cluster within a time interval Δt, out of the total lightning events within that time interval Δt:

[0031]

[0032] in, The utilization rate of all lightning events within the time interval. Let M be the number of lightning events contained in the i-th lightning cluster, and M be the total number of lightning clusters within that time interval. This represents the total number of total lightning events that occurred within this time interval;

[0033] S44: Percentage of lightning cluster area (PS)

[0034]

[0035] in, This represents the number of grids within a lightning cluster that actually contain all lightning data.

[0036] Furthermore, the merging threshold of the final lightning cluster in step S32, which merges to form a new final lightning cluster, is dynamically adjusted according to the life stage of the thunderstorm process. Specifically, this includes the following steps:

[0037] S321: Identify the morphological characteristics of primary lightning clusters within the current time interval, including the number of grids, geometric dimensions, and lightning density distribution of the lightning clusters;

[0038] S322: Determine the thunderstorm life stage based on the morphological characteristics of the primary lightning cluster, wherein the life stage includes the initial stage, development stage, maturity stage and extinction stage;

[0039] S323: Set different edge radial mesh merging thresholds according to different life stages:

[0040] For lightning clusters in the initial and development stages, 8 or 24 neighborhoods are used for merging.

[0041] For lightning clusters in the mature stage, a 48 or 80-neighborhood is used for merging;

[0042] For lightning clusters in the decay phase, a 120 or 168 neighborhood is used for merging.

[0043] S324: Based on the dynamically adjusted merging threshold, primary lightning clusters are merged to obtain final lightning clusters.

[0044] Compared with existing technologies, this invention, through two-stage lightning merging, can effectively identify lightning clusters in the mature, decay, and initial stages simultaneously, and reduce the number of lightning clusters in the mature stage. It enables the identification of lightning activity areas during thunderstorms under different scale requirements, providing technical support for lightning monitoring at the power system scale. By proposing to use lightning cluster area, lightning cluster area ratio, number of lightning clusters within a time interval, and lightning event utilization rate as quantitative indicators of lightning activity areas, it can quantitatively evaluate the identification results of different lightning cluster activity areas, solve the problem of quantitative comparison of identification results of different algorithms, and provide technical support for lightning monitoring at different scales.

[0045] This method classifies and identifies all lightning data (cloud-to-cloud and ground-to-ground lightning) collected by a total lightning location system, divides lightning cluster regions, merges primary lightning clusters into final lightning clusters, and quantifies the identification results. It uses a geographic grid to geographically divide lightning activity areas. First, primary lightning clusters are obtained by using an eight-ray radial grid of adjacent clusters. Then, primary lightning clusters are merged using radial grids of 24, 48, 80, or 120 radii to obtain final lightning clusters. A polygon fitting method is used to determine the lightning cluster regions and describe their characteristics. Finally, the identification results are quantified and evaluated. This method can effectively identify lightning clusters in the mature, dissipating, and initial stages simultaneously, reduce the number of mature lightning clusters, and achieve lightning activity area identification during thunderstorms at different scales. It also allows for quantitative comparison of identification results from different algorithms. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0047] Figure 1 Flowchart of a method for identifying and quantifying all-lightning activity areas in a kilometer-scale grid;

[0048] Figure 2 A schematic diagram of a method for identifying all-lightning activity areas in a kilometer-scale grid.

[0049] Figure 3 A flowchart outlining the specific scheme for identifying and quantifying all-lightning activity areas using a kilometer-scale grid. Detailed Implementation

[0050] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0051] As attached Figure 1 To be continued Figure 3 As shown:

[0052] Example:

[0053] This invention provides a method for identifying and quantifying all-lightning activity areas on a kilometer-scale grid, comprising the following steps:

[0054] S1: Kilometer-scale grid matching of discrete full-lightning data;

[0055] S2: Primary lightning cluster identification based on an eight-ray radial grid;

[0056] S3: Acquisition of final lightning clusters based on edge radial grid;

[0057] S4: Quantitative assessment index of lightning activity area.

[0058] The kilometer-level grid matching of discrete full lightning data in step S1 includes the following sub-steps:

[0059] S11: Within the rectangular area covered by the full-lightning positioning system, the geographical area of ​​the coverage area is gridded, and the grid size can be set as needed;

[0060] S12: Discrete total lightning data within the time interval Δt are assigned to a pre-defined grid according to geographic coordinates to obtain a total lightning density map.

[0061] Furthermore, the grid size can be set to a range of 0.01° to 0.05° as needed, and the time interval Δt can be set to a range of 1 to 15 minutes.

[0062] Furthermore, the primary lightning cluster identification based on an eight-ray radial grid in step S2 includes the following sub-steps:

[0063] S21: The eight-ray radial grid refers to searching from a central grid containing all lightning data in eight directions: left, upper left, top, upper right, right, lower right, bottom, and lower left.

[0064] S22: If the eight-ray radial grid of the central grid described in S21 contains full lightning data, then use this grid as the new central grid and continue to search for the eight-ray radial grid of the new central grid until no new grid is found. All the grids found that contain full lightning data are classified into one category, namely, primary lightning clusters.

[0065] S23: The polygon fitting method is used to fit the primary lightning cluster to obtain the outline region of the primary lightning cluster.

[0066] Furthermore, step S3, the acquisition of the final lightning cluster based on the edge radial grid, includes the following sub-steps:

[0067] S31: Taking grid a in primary lightning cluster A as the center, find whether the grid containing full lightning data within the radial grid range (8, 24, 48, 80, 120, 168 neighborhoods) belongs to primary lightning cluster B;

[0068] S32: If it belongs to primary lightning cluster B, then the two primary lightning clusters merge to form a new final lightning cluster; otherwise, primary lightning cluster A directly forms a final lightning cluster.

[0069] S33: The polygon fitting method is used to fit the final lightning cluster to obtain the outline region of the final lightning cluster.

[0070] It should be noted that the quantitative evaluation index of lightning activity area in step S4 includes the following sub-steps:

[0071] S41: Use the area of ​​the polygon-fitted region as the area S of the lightning cluster. c :

[0072]

[0073] in, N represents the area of ​​a single grid cell, and N is the number of grid cells covered by the lightning cluster.

[0074] S42: The centroid of the lightning cluster is the centroid of the fitted polygon.

[0075]

[0076] in,( ( ) represents the coordinates of each vertex of the fitted polygon. The number of vertices;

[0077] S43: Number of final lightning clusters N, total lightning event utilization rate within time interval Δt, percentage of total lightning events participating in the formation of lightning clusters within time interval Δt.

[0078]

[0079] in, The utilization rate of all lightning events within the time interval. Let M be the number of lightning events contained in the i-th lightning cluster, and M be the total number of lightning clusters within that time interval. This represents the total number of total lightning events that occurred within this time interval;

[0080] S44: Percentage of lightning cluster area (PS)

[0081]

[0082] in, This represents the number of grids within a lightning cluster that actually contain all lightning data.

[0083] Specifically, the merging threshold of the final lightning cluster in step S32, which merges to form a new final lightning cluster, is dynamically adjusted according to the life stage of the thunderstorm process. This includes the following steps:

[0084] S321: Identify the morphological characteristics of primary lightning clusters within the current time interval, including the number of grids, geometric dimensions, and lightning density distribution of the lightning clusters;

[0085] S322: Determine the thunderstorm life stage based on the morphological characteristics of the primary lightning cluster, wherein the life stage includes the initial stage, development stage, maturity stage and extinction stage;

[0086] S323: Set different edge radial mesh merging thresholds according to different life stages:

[0087] For lightning clusters in the initial and development stages, 8 or 24 neighborhoods are used for merging.

[0088] For lightning clusters in the mature stage, a 48 or 80-neighborhood is used for merging;

[0089] For lightning clusters in the decay phase, a 120 or 168 neighborhood is used for merging.

[0090] S324: Based on the dynamically adjusted merging threshold, primary lightning clusters are merged to obtain final lightning clusters.

[0091] Work process: such as Figure 1 A method for identifying and quantifying total lightning activity areas using a kilometer-scale grid is proposed. This method uses a geographic grid to geographically divide lightning activity areas, obtains primary lightning clusters by using adjacent eight-ray radial grids, and then merges these primary lightning clusters using radial grids of 24, 48, 80, or 120 radii to obtain final lightning clusters. A polygon fitting method is used to determine the lightning cluster regions and describe their characteristics. Finally, the identification results are quantitatively evaluated. A schematic diagram of the kilometer-scale grid-based total lightning activity area identification method is shown below. Figure 2 The flowchart for the method of identifying all-lightning activity areas in a kilometer-scale grid is shown below. Figure 3 ;

[0092] Kilometer-scale grid matching of discrete all-lightning data: collecting all-lightning data acquired by the all-lightning location system, see... Figure 2 (a); Within the rectangular area covered by the all-lightning positioning system, the geographic region of the coverage area is gridded, see... Figure 2 (b); The grid size can be set to 0.01°~0.05° as needed;

[0093] Discrete total lightning data within a time interval Δt are distributed into a predefined grid according to geographic coordinates. The time interval can be set to 1–15 minutes to obtain a total lightning density map. (See...) Figure 2 (c).

[0094] Primary lightning cluster identification based on an eight-ray radial grid: The eight-ray radial grid refers to starting from a central grid containing all lightning data and searching in eight directions: left, upper left, top, upper right, right, lower right, bottom, and lower left.

[0095] If the eight-ray radial grid of the central grid described in S21 contains full lightning data, then this grid is used as the new central grid, and the search continues to find the eight-ray radial grid of the new central grid until no new grid is found. All the grids found that contain full lightning data are classified into one category, namely, primary lightning clusters.

[0096] The primary lightning cluster was fitted using a polygon fitting method to obtain its contour region, as shown in [reference needed]. Figure 2 (d);

[0097] Final lightning cluster acquisition based on edge radial grid: Taking grid a in primary lightning cluster A as the center, find whether the grid containing full lightning data within its edge radial grid (neighborhood of 8, 24, 48, 80, 120, 168) belongs to primary lightning cluster B;

[0098] If it belongs to primary lightning cluster B, the two primary lightning clusters will merge to form a new final lightning cluster; otherwise, primary lightning cluster A will directly form a final lightning cluster.

[0099] The final lightning cluster was fitted using a polygon fitting method to obtain its contour region, as shown in [reference needed]. Figure 2 (d);

[0100] Quantitative assessment indicators for lightning activity areas

[0101] The area of ​​the polygon-fitted region is taken as the area S of the lightning cluster. c :

[0102]

[0103] in, N represents the area of ​​a single grid cell, and N is the number of grid cells covered by the lightning cluster.

[0104] The centroid of the lightning cluster is the centroid of the fitted polygon.

[0105]

[0106] in,( ( ) represents the coordinates of each vertex of the fitted polygon. The number of vertices;

[0107] Number of final lightning clusters N, total lightning event utilization rate within time interval Δt, and percentage of total lightning events participating in the formation of lightning clusters within time interval Δt.

[0108]

[0109] in, The utilization rate of all lightning events within the time interval. Let M be the number of lightning events contained in the i-th lightning cluster, and M be the total number of lightning clusters within that time interval. This represents the total number of total lightning events that occurred within this time interval;

[0110] Lightning cluster area percentage (PS):

[0111]

[0112] in, This represents the number of grids within a lightning cluster that actually contain all lightning data.

[0113] During this process, the merging threshold of the final lightning clusters formed by merging is dynamically adjusted according to the life stage of the thunderstorm process.

[0114] Identify the morphological characteristics of primary lightning clusters within the current time interval, including the number of grids, geometric dimensions, and lightning density distribution of the lightning clusters;

[0115] The morphological characteristics of primary lightning clusters determine their thunderstorm life stage, which includes the initial stage, development stage, maturity stage, and extinction stage.

[0116] Set different edge radial mesh merging thresholds according to different life stages:

[0117] For lightning clusters in the initial and development stages, 8 or 24 neighborhoods are used for merging.

[0118] For lightning clusters in the mature stage, a 48 or 80-neighborhood is used for merging;

[0119] For lightning clusters in the decay phase, a 120 or 168 neighborhood is used for merging.

[0120] Based on the dynamically adjusted merging threshold, primary lightning clusters are merged to obtain final lightning clusters.

[0121] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for identifying and quantifying all-lightning activity areas on a kilometer-scale grid, characterized in that, Includes the following steps, S1: Kilometer-scale grid matching of discrete full-lightning data; S2: Primary lightning cluster identification based on an eight-ray radial grid; S3: Acquisition of final lightning clusters based on edge radial grid; S4: Quantitative assessment index of lightning activity area.

2. The method for identifying and quantifying all-lightning activity areas in a kilometer-scale grid according to claim 1, characterized in that, The kilometer-level grid matching of the discrete all-lightning data in step S1 includes the following sub-steps: S11: Within the rectangular area covered by the full-lightning positioning system, the geographical area of ​​the coverage area is gridded, and the grid size can be set as needed; S12: Discrete total lightning data within the time interval Δt are assigned to a pre-defined grid according to geographic coordinates to obtain a total lightning density map.

3. The method for identifying and quantifying all-lightning activity areas in a kilometer-scale grid according to claim 2, characterized in that, The grid size can be set to a range of 0.01° to 0.05° as needed.

4. The method for identifying and quantifying all-lightning activity areas in a kilometer-scale grid according to claim 3, characterized in that, The time interval Δt ranges from 1 to 15 minutes.

5. The method for identifying and quantifying all-lightning activity areas in a kilometer-scale grid according to claim 2 or 4, characterized in that, The primary lightning cluster identification based on an eight-ray radial grid in step S2 includes the following sub-steps: S21: The eight-ray radial grid refers to searching from a central grid containing all lightning data in eight directions: left, upper left, top, upper right, right, lower right, bottom, and lower left. S22: If the eight-ray radial grid of the central grid described in S21 contains full lightning data, then use this grid as the new central grid and continue to search for the eight-ray radial grid of the new central grid until no new grid is found. All the grids found that contain full lightning data are classified into one category, namely, primary lightning clusters. S23: The polygon fitting method is used to fit the primary lightning cluster to obtain the outline region of the primary lightning cluster.

6. The method for identifying and quantifying all-lightning activity areas in a kilometer-scale grid according to claim 5, characterized in that, Step S3, the acquisition of the final lightning cluster based on the edge radial grid, includes the following sub-steps: S31: Taking grid a in primary lightning cluster A as the center, find whether the grid containing full lightning data within the radial grid range (neighborhood of 8, 24, 48, 80, 120, 168) belongs to primary lightning cluster B; S32: If it belongs to primary lightning cluster B, then the two primary lightning clusters merge to form a new final lightning cluster; otherwise, primary lightning cluster A directly forms a final lightning cluster. S33: The polygon fitting method is used to fit the final lightning cluster to obtain the outline region of the final lightning cluster.

7. The method for identifying and quantifying all-lightning activity areas in a kilometer-scale grid according to claim 6, characterized in that, The quantitative evaluation index of lightning activity area in step S4 includes the following sub-steps: S41: The area of ​​the polygon fitting region is taken as the area S of the lightning cluster. c : in, N represents the area of ​​a single grid cell, and N is the number of grid cells covered by the lightning cluster. S42: The centroid of the lightning cluster is the centroid of the fitted polygon. in,( ( ) represents the coordinates of each vertex of the fitted polygon. The number of vertices; S43: Number of final lightning clusters N, total lightning event utilization rate within time interval Δt, percentage of total lightning events participating in the formation of lightning clusters within time interval Δt. in, The utilization rate of all lightning events within the time interval. Let M be the number of lightning events contained in the i-th lightning cluster, and M be the total number of lightning clusters within that time interval. This represents the total number of total lightning events that occurred within this time interval; S44: Lightning cluster area percentage PS: in, This represents the number of grids within a lightning cluster that actually contain all lightning data.

8. The method for identifying and quantifying all-lightning activity areas in a kilometer-scale grid according to claim 7, characterized in that, The merging threshold of the final lightning clusters in step S32, which merges the lightning clusters to form new final lightning clusters, is dynamically adjusted according to the life stage of the thunderstorm process. Specifically, it includes the following steps: S321: Identify the morphological characteristics of primary lightning clusters within the current time interval, including the number of grids, geometric dimensions, and lightning density distribution of the lightning clusters; S322: Determine the thunderstorm life stage based on the morphological characteristics of the primary lightning cluster, wherein the life stage includes the initial stage, development stage, maturity stage and extinction stage; S323: Set different edge radial mesh merging thresholds according to different life stages: For lightning clusters in the initial and development stages, 8 or 24 neighborhoods are used for merging. For lightning clusters in the mature stage, a 48 or 80-neighborhood is used for merging; For lightning clusters in the decay phase, a 120 or 168 neighborhood is used for merging. S324: Based on the dynamically adjusted merging threshold, primary lightning clusters are merged to obtain final lightning clusters.

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