Submarine cable laying path planning method and system capable of avoiding risk in whole course

Abstract

The invention discloses a submarine cable laying path planning method and system capable of avoiding risks in the whole course, and the method comprises the steps: carrying out the rasterization of submarine elevation information, deleting a risk grid unit, and obtaining the grid unit data of a to-be-laid submarine cable region; determining a submarine cable laying starting point grating unit according to the submarine cable laying starting point coordinate, determining a submarine cable laying terminal point grating unit according to the submarine cable laying starting point coordinate, and representing a submarine cable laying path by a continuous grating unit sequence comprising the submarine cable laying starting point grating unit and the submarine cable laying terminal point grating unit; the submarine cable laying path is iteratively optimized by adopting a multi-objective optimization algorithm, and the optimized submarine cable laying path with low laying cost is obtained while the laying risk is controlled. According to the method, the comprehensive objective function considering the whole-course topographic relief and the local slope risk is combined, the whole-course risk and cost of the submarine cable laying path are subjected to multi-objective optimization, and the problem that the submarine cable laying cost is greatly increased or the whole-course reliability is reduced due to the fact that a local risk area is directly avoided is solved.

Description

Technical Field

[0001] The present invention belongs to the field of communication technologies, and more specifically, relates to a method and system for planning a submarine cable laying path with multiple risk avoidance. Background Art

[0002] Submarine cable laying refers to the process of laying submarine cables in an underwater environment, mainly used for transmitting electrical energy or communication signals. The main purpose of submarine cables is to connect power transmission between land and islands, islands and islands, offshore oil and gas exploitation, submarine observation and exploration, marine scientific research, offshore wind power and other marine fields, and plays an important role in offshore power transmission. Submarine cables have high requirements for technology and performance, and need to have good water-blocking performance, mechanical properties, anti-corrosion and anti-biting capabilities to adapt to the complex seabed environment.

[0003] The planning of a submarine cable laying path is a complex and crucial link in submarine cable laying, which involves comprehensive consideration of multiple factors such as seabed topography, geological conditions, marine environment, fishery activities and shipping routes. Through precise measurement and analysis, planners need to design a safe, stable and efficient optical cable laying path. This not only requires avoiding potential natural disaster risk areas, but also ensuring that the laying depth and protection measures of the optical cable are appropriate to resist the long-term erosion of the marine environment. A reasonable routing plan can maximize the transmission efficiency of the optical cable, reduce maintenance costs, and minimize the impact on the surrounding environment and human activities.

[0004] In the planning of a submarine cable laying path on the seabed, slope is one of the core considerations, which directly affects construction feasibility, submarine cable safety and long-term operation and maintenance stability. Areas with large slopes are usually accompanied by risks of geological disasters such as landslides and debris flows. For example, the risk assessment of the North Sea submarine cable project in Denmark pointed out that steep terrain may cause submarine cable fractures or point load wear, and risk mitigation is required through micro-trench technology or additional protection measures. In steep terrains such as Norwegian fjords, the submarine cable path needs to avoid slopes with a slope > 25° to reduce the length of the suspended section. Areas with a slope > 15° are classified as "medium-high risk areas", and the possibility of landslides needs to be evaluated in combination with geological exploration data.

[0005] However, the current consideration of slope risk is based on local consideration of the terrain, avoiding terrains with too large slopes. For a long-distance cross-sea submarine cable laying project, the avoidance of local terrain may cause a huge increase in costs. Therefore, it is necessary to more accurately consider the risks of submarine cable laying, and save costs as much as possible on the premise of ensuring the safety and reliability of submarine cable laying. Summary of the Invention

[0006] In view of the above defects or improvement requirements of the prior art, the present invention provides a method and system for planning a submarine cable laying path with full - process risk avoidance. The purpose is to use a comprehensive objective function that combines the overall terrain undulation and local slope risks to multi - object optimize the full - process risk and cost of the submarine cable laying path, thereby solving the technical problems of a significant increase in the cost of submarine cable laying or a reduction in overall reliability caused by directly bypassing local risk areas.

[0007] To achieve the above object, according to one aspect of the present invention, a method for planning a submarine cable laying path with full - process risk avoidance is provided, which is characterized by including the following steps:

[0008] (1) Obtain the laying conditions of the area where the submarine cable is to be laid, including the starting coordinates of the submarine cable laying, the ending coordinates of the submarine cable laying, and the seabed elevation information of the area where the submarine cable is to be laid;

[0009] (2) Grid - process the seabed elevation information and delete the risk grid cells to obtain the grid cell data of the area where the submarine cable is to be laid; determine the starting grid cell of the submarine cable laying according to the starting coordinates of the submarine cable laying, and determine the ending grid cell of the submarine cable laying according to the ending coordinates of the submarine cable laying. Represent the submarine cable laying path by a continuous grid cell sequence including the starting grid cell and the ending grid cell of the submarine cable laying;

[0010] (3) Use a multi - objective optimization algorithm to iteratively optimize the submarine cable laying path defined in step (2) to obtain an optimized submarine cable laying path with low laying cost while controlling the laying risk. Among them, the optimization objective of the optimization algorithm is: the minimum value of the comprehensive objective function;

[0011] The comprehensive objective function is specifically:

[0012] F = w1F tr + w2F s + w3F p + w4F c

[0013] Wherein, w1, w2, w3, and w4 are weight coefficients; F tr is the terrain risk, which is used to characterize the terrain undulation degree of the whole submarine cable laying path; F s is the slope risk, which is used to characterize the reliability risk caused by the bending of the submarine cable due to the slope in each local part of the submarine cable laying path; F p is the pipeline risk, which is used to characterize the reliability risk of the submarine cable caused by being close to other pipelines during the whole process of submarine cable laying; F c is the cost, which is used to characterize the cost of the whole submarine cable laying process.

[0014] Preferably, in the method for planning a submarine cable laying path with full - process risk avoidance, the grid cells of the area where the submarine cable is to be laid in step (2) form a connected area;

[0015] Specifically,

[0016] The submarine cable laying path P is denoted as: P = [(x1,y1),(x2,y2),…,(x n ,y n )], where P i (x i ,y i ), i = 1, 2, …, n represents the coordinates on the i-th grid cell on the submarine cable laying path P, and there is the following relationship between P i and P i+1 : |x i+1 -x i | ≤ d x and |y i+1 -y i | ≤ d y , |x i+1 -x i | > 0 or |y i+1 -y i | > 0, i = 1, 2, …, n - 1, d x is the number of pixels on the x-axis of the grid cell, d y is the number of pixels on the y-axis of the grid cell, and n is the number of horizontal grid cell rows or vertical grid cell columns between the starting grid cell and the ending grid cell of the submarine cable laying, preferably the larger one of them.

[0017] Preferably, for the submarine cable laying path planning method with full-process risk avoidance, the grid cells in the area where the submarine cable is to be laid have a slope less than a preset threshold.

[0018] Preferably, for the submarine cable laying path planning method with full-process risk avoidance, the grid cells in the area where the submarine cable is to be laid do not include pipeline risk grid cells, and the pipeline risk grid cells are determined as follows:

[0019] For each existing pipeline in the area where the submarine cable is to be laid:

[0020] Determine the pipeline risk distance threshold according to its pipeline type;

[0021] Regard the areas on both sides of the pipeline path with a distance less than its risk distance threshold from the pipeline as the pipeline risk areas;

[0022] Convert the pipeline risk areas through gridification to a set of risk grid cells.

[0023] The pipeline types include optical cables, submarine cables or oil and gas pipelines, and the pipeline risk distance thresholds for each type are determined according to the physical and chemical characteristics of that type of pipeline.

[0024] Preferably, for the submarine cable laying path planning method with full - process risk avoidance, the terrain risk \(F\) in step (3) tr is calculated as follows:

[0025]

[0026] where \(H\) i is the average height value of the pixels in the \(i\) - th grid cell, calculated according to the seabed elevation information of the \(i\) - th grid cell, is the arithmetic mean of the average height values of the grid cells included in the submarine cable laying path \(P\),

[0027] Preferably, for the submarine cable laying path planning method with full - process risk avoidance, the slope risk \(F\) in step (3) s is calculated as follows:

[0028]

[0029] where \(s\) i is the slope in the \(i\) - th grid cell, that is, the change rate of the terrain height, \(S\) is the slope reference value. When the slope in the grid cell is less than or equal to the slope reference value, it is considered that the bending degree of the submarine cable is small, and the laying risk caused by local bending can be ignored; \(u\) is a penalty index factor used to control the penalty intensity for too large slopes. When \(u>1\), the larger the slope value, the heavier the penalty; when \(u = 1\), the penalty is proportional to the slope value; when \(0<u<1\), the penalty intensity increases more slowly with the increase of the slope.

[0030] Preferably, for the submarine cable laying path planning method with full - process risk avoidance, the pipeline risk \(F\) in step (3) p is calculated as follows:

[0031]

[0032] where \(A\) i is the number of pixels overlapping with the pipeline buffer area in the \(i\) - th grid cell, \(A_0\) is the number of pixels in the grid cell, and the pipeline buffer area is the area outside the pipeline risk area and less than the buffer distance threshold from the pipeline.

[0033] Preferably, for the submarine cable laying path planning method with full - process risk avoidance, the cost \(F\) in step (3) c is calculated as follows:

[0034]

[0035] where \(d\) i is the coordinate \((x\) i ,y\) of each grid point on the optical cable pathi ) The distance (x i+1 , y i+1 ) between adjacent grid points, D i is the depth of the i-th grid cell, and c(D i ) is the unit construction cost of the area with depth D i , which is determined as follows:

[0036]

[0037] Among them, c is the construction cost, c deep is the cost of the submarine cable in the deep sea area, c shallow is the cost of the submarine cable in the shallow sea area, and D th is the water depth threshold.

[0038] Preferably, in the submarine cable laying path planning method for full-course risk avoidance, in step (3), an improved particle swarm algorithm is used to optimize the submarine cable laying path. The specific scheme is as follows: The position vector of each particle represents a potential submarine cable laying path P = [(x1, y1), (x2, y2), …, (x n , y n )], a new potential submarine cable laying path is generated by simulating the particle movement, a fitness function is constructed with the optimization objective, particles with high fitness are selected and iterated until convergence to obtain the optimized submarine cable laying path.

[0039] In a preferred solution, an elitist retention strategy is adopted to update the particle movement to generate a new potential submarine cable laying path.

[0040] In a preferred solution, an inertia weight dynamic adjustment strategy is adopted to update the particles to generate a new potential submarine cable laying path, so that the particle inertia weight coefficient in the early stage of iterative optimization is greater than that in the later stage of iterative optimization to improve the global search ability in the early stage and the local search ability in the later stage.

[0041] According to another aspect of the present invention, a submarine cable laying path planning system for full-course risk avoidance is provided. The system is an electronic device or a non-transitory computer-readable storage medium;

[0042] The electronic device includes a memory, a processor, and a computer program stored on the memory and executable on the processor. It is characterized in that when the processor executes the program, the steps of the submarine cable laying path planning method provided by the present invention are implemented.

[0043] The non-transitory computer-readable storage medium stores a computer program. It is characterized in that when the computer program is executed by the processor, the steps of the submarine cable laying path planning method provided by the present invention are implemented.

[0044] Generally speaking, compared with the prior art, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0045] The submarine cable laying path planning and system with full - process risk avoidance provided by the present invention takes into account the undulations of the entire submarine cable laying path and the influence of local slopes, fully considers the risk factors caused by the terrain, effectively provides reliability, and at the same time avoids the reduction of reliability caused by the terrain risk of the entire laying path due to directly bypassing local high - risk areas or the substantial increase in cost caused by an overly long submarine cable laying path.

[0046] The preferred solution combines the improved particle swarm algorithm to optimize the submarine cable laying path, which can effectively search for the optimal submarine cable laying path globally, reduce the omission of considering the risk of local slopes and thus reducing the overall terrain risk or cost due to a small number of iterations. Moreover, the elite retention strategy is adopted to update the particle movement, effectively reducing the number of iterations required. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is a schematic flow chart of the method for planning the submarine cable laying path with full - process risk avoidance provided by the embodiment of the present invention;

[0048] Figure 2 is a schematic diagram of the pipeline risk area and the pipeline buffer area in the embodiment of the present invention.

[0049] In all the drawings, the same reference numerals are used to represent the same elements or structures, where: 1 is the pipeline risk area, and 2 is the pipeline buffer area. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0050] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0051] The method for planning the submarine cable laying path with full - process risk avoidance provided by the present invention includes the following steps:

[0052] (1) Obtain the laying conditions of the area where the submarine cable is to be laid, including the starting coordinates of the submarine cable laying, the ending coordinates of the submarine cable laying, and the seabed elevation information of the area where the submarine cable is to be laid;

[0053] (2)Rasterize the seabed elevation information and delete the risk grid cells to obtain the grid cell data of the area where the submarine cable is to be laid; determine the grid cell at the starting point of the submarine cable laying according to the starting point coordinates of the submarine cable laying, and determine the grid cell at the ending point of the submarine cable laying according to the starting point coordinates of the submarine cable laying, and represent the submarine cable laying path by a continuous grid cell sequence including the grid cell at the starting point of the submarine cable laying and the grid cell at the ending point of the submarine cable laying; specifically,

[0054] The submarine cable laying path P is denoted as: P = [(x1, y1), (x2, y2), …, (x n , y n )], where P i (x i , y i ), i = 1, 2, …, n represents the coordinates on the i-th grid cell on the submarine cable laying path P, and there is the following relationship between P i and P i+1 : |x i+1 - x i | ≤ d x and |y i+1 - y i | ≤ d u , |x i+1 - x i | > 0 or |y i+1 - y i | > 0, i = 1, 2, …, n - 1, d x is the number of pixels on the x-axis of the grid cell, d y is the number of pixels on the y-axis of the grid cell, and n is the number of horizontal grid cell rows or vertical grid cell columns between the grid cell at the starting point of the submarine cable laying and the grid cell at the ending point of the submarine cable laying, preferably the larger one.

[0055] The risk grid cell is a grid cell in a high-risk area, and the high-risk area includes geological risk areas such as seismic zones and submarine landslide areas; human activity areas such as fishing-intensive areas, waterways and anchorages; environmentally sensitive areas such as coral reefs and ecological protection areas; and engineering difficulty areas such as hard rock geology.

[0056] Preferably, for the grid cells in the area where the submarine cable is to be laid, the slope is less than a preset threshold.

[0057] Preferably, the grid cells in the area where the submarine cable is to be laid do not include pipeline risk grid cells, and the pipeline risk grid cells are determined according to the following method:

[0058] For each existing pipeline in the area where the submarine cable is to be laid:

[0059] Determine the pipeline risk distance threshold according to its pipeline type;

[0060] Regard the areas on both sides of the pipeline path with a distance less than its risk distance threshold from the pipeline as the pipeline risk areas;

[0061] Perform rasterization on the pipeline risk areas to convert them into a set of risk raster cells.

[0062] The pipeline types include optical cables, submarine cables or oil and gas pipelines, and the risk distance thresholds for each type of pipeline are determined according to the physical and chemical characteristics of that type of pipeline.

[0063] The grid cells in the area where the submarine cable is to be laid form a connected area.

[0064] (3) Use a multi-objective optimization algorithm to iteratively optimize the submarine cable laying path defined in step (2) to obtain an optimized submarine cable laying path with low laying cost while controlling the laying risk. Among them, the optimization objective of the optimization algorithm is: the minimum value of the comprehensive objective function;

[0065] The comprehensive objective function is specifically:

[0066] F = w1F tr + w2F s + w3F p + w4F c

[0067] Among them, w1, w2, w3 and w4 are weight coefficients; F tr is the terrain risk, which is used to characterize the terrain undulation degree of the entire submarine cable laying path; F s is the slope risk, which is used to characterize the reliability risk caused by the bending of the submarine cable due to the slope in each part of the submarine cable laying path; F p is the pipeline risk, which is used to characterize the reliability risk of the submarine cable caused by being close to other pipelines during the entire submarine cable laying process; F c is the cost, which is used to characterize the cost of the entire submarine cable laying process. Specifically:

[0068] The terrain risk F tr , is calculated according to the following method:

[0069]

[0070] Among them, H i is the average height value of the pixels in the i-th grid cell, which is calculated according to the seabed elevation information of the i-th grid cell, is the arithmetic mean of the average height values of the grid cells included in the submarine cable laying path P,

[0071] The slope risk F s , is calculated according to the following method:

[0072]

[0073] Among them, s i is the slope within the i-th grid cell, that is, the change rate of the terrain height. S is the slope reference value. When the slope within the grid cell is less than or equal to the slope reference value, it is considered that the bending degree of the submarine cable is small, and the laying risk caused by local bending can be ignored; u is a penalty exponent factor used to control the penalty intensity for excessive slopes. When u > 1, the larger the slope value, the heavier the penalty; when u = 1, the penalty is proportional to the slope value; when 0 < u < 1, the penalty intensity increases more slowly with the increase of the slope.

[0074] The slope risk can reflect the risk of local stress caused by bending. The slope risk and the terrain risk cooperate with each other to more accurately evaluate the cumulative risk of the reduction of the reliability of the optical cable laying caused by the terrain throughout the submarine cable laying path. And appropriately incorporating the grid cells with larger local slopes into the submarine cable laying path range avoids the situation of a significant increase in the path or a reduction in the overall reliability of the submarine cable laying path caused by directly bypassing local terrain using the threshold method.

[0075] Pipeline risk F p , is calculated according to the following method:

[0076]

[0077] Among them, A i is the number of pixels overlapping with the pipeline buffer zone within the i-th grid cell, A0 is the number of pixels in the grid cell, and the pipeline buffer area is the area outside the pipeline risk area with a distance less than the buffer distance threshold from the pipeline.

[0078] Cost F c , is calculated according to the following method:

[0079]

[0080] Among them, d i is the distance between the coordinates (x i , y i ) of each grid point on the optical cable path and the adjacent grid point (x i+1 , y i+1 ), D i is the depth of the i-th grid cell, c(D i ) is the unit cost of the area with a depth of D i , and is determined according to the following method:

[0081]

[0082] Among them, c is the construction cost, c deep is the submarine cable cost in the deep sea area, c shallow is the submarine cable cost in the shallow sea area, Dth is the water depth threshold.

[0083] Preferably, an improved particle swarm algorithm is used to optimize the submarine cable laying path. The specific scheme is as follows: The position vector of each particle represents a potential submarine cable laying path P = [(x1, y1), (x2, y2), …, (x n , y n )], simulate the particle movement to generate new potential submarine cable laying paths, construct a fitness function with the optimization objective, screen the particles with high fitness and iterate until convergence to obtain the optimized submarine cable laying path.

[0084] In a preferred scheme, an elite retention strategy is adopted to update the particle movement and generate new potential submarine cable laying paths.

[0085] In a preferred scheme, an inertia weight dynamic adjustment strategy is adopted to update the particles to generate new potential submarine cable laying paths, so that the particle inertia weight coefficient in the early stage of iterative optimization is greater than that in the later stage of iterative optimization, in order to improve the global search ability in the early stage and the local search ability in the later stage.

[0086] The following are examples:

[0087] The submarine cable laying path planning method for full-process risk avoidance provided in this embodiment, as Figure 1 shown, includes the following steps:

[0088] (1) Obtain the laying conditions of the area where the submarine cable is to be laid, including the starting coordinates of the submarine cable laying, the ending coordinates of the submarine cable laying, and the seabed elevation information of the area where the submarine cable is to be laid; specifically:

[0089] In a geographic information system (GIS) software, import the map of the submarine optical cable routing area as the base map, and this base map contains a vector layer or raster layer with information such as the coastline, islands, land, and ocean boundaries.

[0090] Collect and organize the longitude and latitude coordinate data of risk areas (such as submarine landslides, fishing activity areas, submarine cable intersection areas, etc.) and existing pipelines (including other submarine optical cables, oil and gas pipelines, etc.).

[0091] Create a new point layer or line layer in the GIS and import this coordinate data into the corresponding layer.

[0092] According to the coordinate data, the GIS software automatically generates distribution maps of risk areas and existing pipelines, and these layers will be displayed on the base map in the form of points or lines.

[0093] Obtain the digital elevation model (DEM) data of the area from the Global Multi-Resolution Topography (GMRT) database.

[0094] (2) Rasterize the seabed elevation information and delete the risk raster cells to obtain the grid cell data of the area where the submarine cable is to be laid; specifically as follows:

[0095] The size of the raster cell is less than 200m * 200m;

[0096] Import the DEM data into GIS as a raster layer, and use the slope analysis tool of the GIS software to calculate the slope based on the DEM raster data, so as to obtain the slope raster layer and elevation layer of this sea area. The slope is the rate of change in height between two adjacent raster cells, usually expressed as a percentage or degrees.

[0097] Overlay the risk area and pipeline layer with the base map, and conduct analysis and processing in a two-dimensional plane, dividing the continuous space into a series of discrete raster cells. At the same time, in the GIS software, ensure the alignment of the raster data by setting environmental variables. Specify the digital elevation raster layer as the benchmark for alignment. Other layers are rasterized, and their raster points will be automatically aligned to the raster points of the reference raster.

[0098] Define a two-dimensional coordinate system in GIS. The raster point is the center point of the raster cell and has a unique coordinate (x, y). The coordinate system is consistent with the base map and the imported data. If the coordinate systems used for data such as the base map, risk area, and existing pipelines are inconsistent, perform projection conversion to ensure that all layers can be correctly aligned and overlaid in GIS. Among them, for the raster point coordinates of the risk area and pipeline boundary, the nearest raster center coordinates are used for processing.

[0099] Extract the height (or depth) information of the seabed terrain from the DEM data, and at the same time assign the processed slope attribute to each raster point.

[0100] Finally, a raster image containing various attribute information is obtained, and each raster point contains the height (or depth), slope, and coordinate information of the seabed terrain.

[0101] In the above raster image, the following raster cells are excluded:

[0102] 1. The risk raster cells are the raster cells in high-risk areas. High-risk areas include geological risk areas such as seismic zones and submarine landslide areas; human activity areas such as fishing-intensive areas, waterways, and anchorages; environmentally sensitive areas such as coral reefs and ecological protection areas; and engineering difficulty areas such as hard rock geology.

[0103] 2. The raster cells with a slope greater than 30°. Usually, in order to ensure the reliability of submarine cable laying, raster cells with a slope greater than 20° need to be bypassed. Through the constraint of the whole-process terrain risk in the present invention, the tolerance for local slopes is improved, and the slope threshold of the raster cells is increased to 30°.

[0104] 3. Pipeline risk grid cells, which are determined by the following method:

[0105] For each existing pipeline in the area where the submarine cable is to be laid:

[0106] Determine the pipeline risk distance threshold according to its pipeline type;

[0107] Regard the area on both sides of the pipeline path with a distance less than its risk distance threshold from the pipeline as the pipeline risk area;

[0108] Convert the pipeline risk area through grid processing into a set of risk grid cells.

[0109] The pipeline types include optical cables, submarine cables or oil and gas pipelines, and the pipeline risk distance thresholds for each type are determined according to the physical and chemical characteristics of that type of pipeline.

[0110] Obtain the grid cell data of the area where the submarine cable is to be laid. It should be noted that the grid cells of the area where the submarine cable is to be laid form a connected area. Otherwise, it is necessary to consider adjusting the pipeline risk distance threshold, slope threshold and risk grid cells in turn to ensure that the grid cells of the area where the submarine cable is to be laid form a connected area.

[0111] Determine the grid cell at the starting point of the submarine cable laying according to the starting point coordinates of the submarine cable laying. According to the starting point coordinates of the submarine cable laying, determine the grid cell at the ending point of the submarine cable laying, and represent the submarine cable laying path by a continuous grid cell sequence including the grid cell at the starting point of the submarine cable laying and the grid cell at the ending point of the submarine cable laying; specifically,

[0112] The submarine cable laying path P is denoted as: P = [(x1, y1), (x2, y2), …, (x n , y n )], where P i (x i , y i ), i = 1, 2, …, n represents the coordinates on the i-th grid cell on the submarine cable laying path P, and there is the following relationship between P i and P i+1 : |x i+1 - x i | ≤ d x and |y i+1 - y i | ≤ d y , |x i+1 - x i | > 0 or |y i+1 - y i | > 0, i = 1, 2, …, n - 1, d x is the number of pixels on the x-axis of the grid cell, d yis the number of pixels on the y-axis of the grid cell, and n is the number of horizontal grid cell rows or vertical grid cell columns between the grid cell at the starting point of submarine cable laying and the grid cell at the ending point of submarine cable laying, preferably the larger one.

[0113] (3) Use a multi-objective optimization algorithm to iteratively optimize the submarine cable laying path defined in step (2), and obtain an optimized submarine cable laying path with low laying cost while controlling the laying risk. Among them, the optimization objective of the optimization algorithm is: the minimum value of the comprehensive objective function;

[0114] The comprehensive objective function is specifically:

[0115] F = w1F tr + w2F s + w3F p + w4F c

[0116] Among them, w1, w2, w3, and w4 are weight coefficients; F tr is the terrain risk, which is used to characterize the terrain undulation degree of the whole submarine cable laying path; F s is the slope risk, which is used to characterize the reliability risk caused by the bending of the submarine cable due to the slope at each local part of the submarine cable laying path; F p is the pipeline risk, which is used to characterize the reliability risk of the submarine cable caused by being close to other pipelines during the whole submarine cable laying; F c is the cost, which is used to characterize the cost of the whole submarine cable laying. Specifically:

[0117] The terrain risk F tr , is calculated according to the following method:

[0118]

[0119] Among them, H i is the average height value of the pixels in the i-th grid cell, calculated according to the seabed elevation information of the i-th grid cell, is the arithmetic mean of the average height values of the grid cells included in the submarine cable laying path P,

[0120] The slope risk F s , is calculated according to the following method:

[0121]

[0122] Among them, s iis the slope within the \(i\)-th grid cell, i.e., the rate of change of the terrain height. \(S\) is the slope reference value. When the slope within the grid cell is less than or equal to the slope reference value, it is considered that the bending degree of the submarine cable is small, and the laying risk caused by local bending can be ignored. \(u\) is a penalty index factor used to control the penalty intensity for excessive slopes. When \(u > 1\), the greater the slope value, the heavier the penalty. When \(u = 1\), the penalty is proportional to the slope value. When \(0 < u < 1\), the penalty intensity increases more slowly with the increase of the slope.

[0123] The slope risk can reflect the risk of local stress caused by bending. The slope risk and the terrain risk cooperate with each other to more accurately evaluate the cumulative risk of the reduction of the reliability of the optical cable laying caused by the terrain throughout the submarine cable laying path. Appropriately including the grid cells with larger local slopes in the submarine cable laying path range avoids the situation of a significant increase in the path or a reduction in the overall reliability of the submarine cable laying path caused by directly bypassing the local terrain using the threshold method.

[0124] Pipeline risk \(F\) p , is calculated as follows:

[0125]

[0126] where \(A\) i is the number of pixels overlapping with the pipeline buffer zone within the \(i\)-th grid cell, \(A_0\) is the number of pixels in the grid cell, and the pipeline buffer area is the area outside the pipeline risk area and less than the buffer distance threshold from the pipeline. As shown in Figure 2 , the pipeline risk area is the area shown by the solid line, and the pipeline buffer area is the area between the dotted line and the solid line.

[0127] Cost \(F\) c , is calculated as follows:

[0128]

[0129] where \(d\) i is the distance between the coordinates \((x\) i , \(y\) i ) of each grid point on the optical cable path and the adjacent grid point \((x\) i+1 , \(y\) i+1 ), \(D\) i is the depth of the \(i\)-th grid cell, and \(c(D\) i ) is the unit cost of the area with a depth of \(D\) i , which is determined as follows:

[0130]

[0131] where \(c\) is the construction cost, \(c\) deep is the submarine cable cost in the deep sea area, \(c\)shallow is the submarine cable cost in the shallow sea area, D th is the water depth threshold.

[0132] In this embodiment, D th = 1000m, that is, in the deep sea area (the average depth of the grid unit is greater than or equal to 1000m), the laying method of the optical cable is laying, and light armored or non-armored submarine optical cables are used. The submarine cable cost is c deep , in the shallow sea area and the landing part (the average depth of the grid unit is less than 1000m), the laying method of the optical cable is burying, and armored submarine optical cables or special protection type optical cables are used. The submarine cable cost is c shallow .

[0133] In this embodiment, an improved particle swarm algorithm is used to optimize the submarine cable laying path. The specific scheme is as follows: The position vector of each particle represents a potential submarine cable laying path P = [(x1, y1), (x2, y2), …, (x n , y n )], simulate the particle movement to generate a new potential submarine cable laying path, construct a fitness function with the optimization target, screen the particles with high fitness and iterate until convergence to obtain the optimized submarine cable laying path.

[0134] In this embodiment, an elite retention strategy is used to update the particle movement and generate a new potential submarine cable laying path. Specifically as follows:

[0135] S1. Initialize the particle swarm, set the number of particles N, the position P and velocity V of the particles. Randomly generate a group of particles, and each particle has a random position and velocity.

[0136] Particle position: The submarine cable laying path P is denoted as: P = [(x1, y1), (x2, y2), …, (x n , y n )], where P i (x i , y i ), i = 1, 2, …, n represents the coordinates on the i-th grid unit of the submarine cable laying path P.

[0137] S2. Fitness evaluation, take the reciprocal of the comprehensive objective function as the fitness function, then calculate the fitness value of the particles, and select the particles with high fitness values.

[0138] Preferred solution, adopt an inertia weight dynamic adjustment strategy to update the particles to generate a new potential submarine cable laying path, so that the particle inertia weight coefficient in the early stage of iterative optimization is greater than that in the later stage of iterative optimization, in order to improve the global search ability in the early stage and the local search ability in the later stage.

[0139] S3. Update the individual best position, global best position, and elite average position

[0140] The individual best position is the path position of the particle with the highest fitness among the particles generated in this iteration; written as:

[0141]

[0142] The global best position gbest is the path position of the particle with the highest fitness in the entire particle swarm. After each iteration, compare the fitness of the particle at the newly iterated individual best position and the particle at the currently stored global best position. If the fitness of the particle at the newly iterated individual best position is higher than that of the particle at the currently stored global best position, then use the newly iterated individual best position as the global best position for global best position update; written as:

[0143]

[0144] In the submarine cable route planning, the global best position represents the optimal solution among all current potential paths and is an embodiment of the global search ability of the algorithm.

[0145] The elite average position ebest is the combined mean vector of elite individual positions; written as:

[0146]

[0147] where E is the set of elite individuals.

[0148] S4. Update particle individuals

[0149] In each iteration, the position of the particle is updated according to its preset speed and acceleration to generate a new submarine cable laying path. The updated cable route is still composed of continuous grid points.

[0150] This embodiment introduces an elite retention strategy for particle individual update, specifically as follows:

[0151] According to the magnitude of the fitness value, select the K particles with small fitness values in the current iteration as a group of elite solutions and save them in the elite archive. These elite solutions will be used as references in subsequent iterations to guide other particles to move towards better solutions.

[0152] The elite solutions in the elite archive (Elite Archive) will be used as additional reference points to update the speed and position of the particles. There are K elite solutions in the elite archive, and the average position of these solutions is used as an additional guiding term. The particle speed and position update formulas are as follows:

[0153]

[0154] where ω is the inertia weight; are the velocity components in the x and y directions at position i at time t; ε1, ε2, and ε2 are the individual learning factor, social learning factor, and elite learning factor respectively; γ1, γ2, and γ3 are the individual random factor, social random factor, and elite random factor respectively, and are random numbers taken between 0 and 1; and are the abscissa of the i-th grid cell of the individual optimal particle pbest, the global optimal particle gbest, and the mean abscissa of the i-th grid cell of the elite individual set respectively; and are the ordinate of the i-th grid cell of the individual optimal particle pbest, the global optimal particle gbest, and the mean ordinate of the i-th grid cell of the elite individual set respectively.

[0155] In the routing planning of submarine optical cables, during the optimization process of the original particle swarm optimization algorithm, the particles are constantly moving and updating. On the one hand, it will increase the search time. On the other hand, for the solutions with high fitness values during the search process, they may gradually deviate from the optimal solution due to randomness and update rules.

[0156] The elite retention strategy avoids the loss of these excellent solutions in subsequent iterations by retaining them in the elite archive, thus ensuring the effectiveness of the algorithm during the search process. The algorithm can conduct further search and optimization based on the known excellent solutions in the next iteration, greatly reducing the scope of ineffective search and enabling the algorithm to approach the global optimal solution faster.

[0157] In this embodiment, the inertia weight is improved, and the inertia weight coefficient ω is dynamically adjusted as:

[0158]

[0159] where ω min is the minimum value of the preset inertia weight coefficient, ω max is the maximum value of the preset inertia weight coefficient, t is the current iteration number, T is the maximum iteration number, and k is a self-adjustable positive integer used to control the amplitude of ω decreasing with the iteration number.

[0160] By dynamically adjusting the inertia weight coefficient ω, in the early stage of the particle swarm algorithm search, the value of ω will be close to ω max , which helps the algorithm maintain a high search range and find the possible region of the global optimal solution, and helps avoid the algorithm converging to the local optimal solution prematurely; in the later stage of exploration, ω is close to ω max , and the particles conduct a detailed search in the possible optimal solution region in the search space.

[0161] In addition, the following update scheme can also be adopted. In the early and late stages of the iterative process of the particle swarm optimization algorithm, the global search ability is increased in the early stage, the local search ability is increased in the late stage, and the local optimum is jumped out. A perturbation strategy is introduced, and a part of the particles are randomly selected for perturbation, and the positions and velocities of the randomly perturbed particles are adjusted.

[0162]

[0163] Among them, λ is the perturbation factor. A larger value is given to λ in the early stage of the algorithm search, so that the particles have a larger velocity and the global search ability is improved. In the late stage of the algorithm search, the perturbation term is increased to ensure that the particles have a certain velocity, the local search ability is increased, and the possibility for the particles to jump out of the local optimum is provided.

[0164] In the submarine cable laying path planning method based on multi-objective optimization and full-process risk aversion of the present invention, it is possible to select a submarine cable laying path with a shorter local high slope but smaller overall risk and cost, replacing the path with large undulations throughout by directly avoiding it. The problems that in the existing submarine cable laying path planning method, the local high slope area is directly avoided, resulting in a reduction in the overall reliability of the submarine cable or a long route with high cost, are effectively avoided.

[0165] It is easy for those skilled in the art to understand that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for planning a submarine cable laying path with full risk avoidance, characterized in that: The following steps are involved: (1) Obtaining the laying conditions of the area where the submarine cable is to be laid, including the coordinates of the starting point of the submarine cable laying, the coordinates of the end point of the submarine cable laying, and the seabed elevation information of the area where the submarine cable is to be laid; (2) rasterizing the seabed elevation information and deleting risky grid cells to obtain grid cell data of the area where the submarine cable is to be laid; Determine the starting grid unit of the submarine cable laying according to the starting coordinates of the submarine cable laying, determine the ending grid unit of the submarine cable laying according to the starting coordinates of the submarine cable laying, and represent the submarine cable laying path with a continuous grid unit sequence including the starting grid unit of the submarine cable laying and the ending grid unit of the submarine cable laying; (3) using a multi-objective optimization algorithm to iteratively optimize the submarine cable laying path defined in step (2), and obtaining an optimized submarine cable laying path with low laying cost while controlling the laying risk, wherein the optimization goal of the optimization algorithm is: minimizing the value of the comprehensive objective function; The comprehensive objective function is specifically: F=w1F tr +w2F s +w3F p +w4F c Among them, w1, w2, w3 and w4 are weight coefficients; F tr F is the terrain risk, which is used to characterize the terrain undulation along the entire cable laying path; s F is the slope risk, which is used to characterize the reliability risk caused by the bending of the submarine cable due to the slope in each part of the submarine cable laying path; p F is the pipeline risk, which is used to characterize the reliability risk of the submarine cable caused by the proximity of the submarine cable to other pipelines during the entire process of laying; c It is the construction cost, used to characterize the entire cost of laying submarine cables.

2. The method for planning a submarine cable laying path with full risk avoidance as claimed in claim 1, characterized in that: Step (2) the grid units in the area where the submarine cable is to be laid form a connected area; Specifically, The submarine cable laying path P is recorded as: P = [(x1, y1), (x2, y2), ..., (x n ,y n )], where P i (x i ,y i ), i = 1, 2, ..., n represents the coordinates of the i-th grid cell on the submarine cable laying path P, P i With P i+1 The following relationship exists: |x i+1 ―x i |≤d x And|y i+1 ―y i |≤d y ,|x i+1 ―x i |>0 or |y i+1 ―y i |>0,i=1,2,…,n―1,d x is the number of pixels on the x-axis of the grid cell, d y is the number of pixels on the y-axis of the grid unit, and n is the number of horizontal grid unit rows or vertical grid unit columns between the grid unit at the starting point of submarine cable laying and the grid unit at the end point of submarine cable laying, and the larger one is preferred.

3. The method for planning a submarine cable laying path with full risk avoidance as claimed in claim 1, characterized in that: The slope of the grid unit in the area where the submarine cable is to be laid is less than a preset threshold.

4. The method for planning a submarine cable laying path with full risk avoidance as claimed in claim 1, characterized in that: The grid unit of the area where the submarine cable is to be laid does not include the pipeline risk grid unit, and the pipeline risk grid unit is determined according to the following method: For each existing pipeline in the area where the submarine cable is to be laid: Determine pipeline risk distance threshold according to pipeline type; The areas on both sides of the pipeline path that are less than the risk distance threshold are regarded as pipeline risk areas; The pipeline risk area is converted into a set of risk grid cells through rasterization. The pipeline types include optical cables, submarine cables or oil and gas pipelines, and the risk distance threshold of each type of pipeline is determined according to the physical and chemical characteristics of the type of pipeline.

5. The method for planning a submarine cable laying path with full risk avoidance as claimed in claim 1, characterized in that: Step (3) The terrain risk F tr , calculated as follows: Among them, H i is the average height value of the pixels in the ith grid cell, calculated based on the seafloor elevation information of the ith grid cell. is the arithmetic mean of the average height values ​​of the grid cells included in the submarine cable laying path P, 6. The method for planning a submarine cable laying path with full risk avoidance as claimed in claim 1, characterized in that: Step (3) Slope risk F s , calculated as follows: where s i is the slope within the i-th grid cell, i.e., the rate of change of the terrain height, S is the slope reference value. When the slope within the grid cell is less than or equal to the slope reference value, it is considered that the bending degree of the submarine cable is small, and the laying risk caused by local bending can be ignored; u is a penalty exponent factor used to control the penalty intensity for too large slopes. When u > 1, the larger the slope value, the heavier the penalty; when u = 1, the penalty is proportional to the slope value; when 0 < u < 1, the rate of increase of the penalty intensity with the increase of the slope is slower.

7. The method for planning a submarine cable laying path with full risk avoidance as claimed in claim 1, characterized in that: Step (3) Pipeline risk F p , calculated as follows: Among them, A i is the number of pixels in the i-th grid unit that overlap with the pipeline buffer, A0 is the number of pixels in the grid unit, and the pipeline buffer area is the area outside the pipeline risk area whose distance from the pipeline is less than the buffer distance threshold.

8. The method for planning a submarine cable laying path with full risk avoidance as claimed in claim 1, characterized in that: The cost F in step (3) c , calculated as follows: Among them, d i is the coordinates of each grid point on the optical cable path (x i ,y i ) and the distance between adjacent grid points (x i+1 ,y i+1 ), D i is the depth of the i-th grid cell, c(D i ) is the depth D i The regional unit cost is determined as follows: Among them, c is the construction cost, c deep is the cost of submarine cables in deep sea areas, c shallow is the cost of submarine cables in shallow waters, D th is the water depth threshold.

9. The method for planning a submarine cable laying path with full risk avoidance as claimed in claim 1, characterized in that: The step (3) uses an improved particle swarm algorithm to optimize the cable laying path. The specific scheme is as follows: the position vector of each particle represents a potential cable laying path P = [(x1, y1), (x2, y2), ..., (x n ,y n )], simulate particle motion to generate new potential submarine cable laying paths, construct fitness function to optimize the target, select particles with high fitness and iterate until convergence to obtain the optimized submarine cable laying path. The optimal solution is selected, and the elite retention strategy is adopted to update the particle motion and generate new potential submarine cable laying paths. The optimal solution adopts the inertia weight dynamic adjustment strategy to update particles to generate new potential submarine cable laying paths, so that the particle inertia weight coefficient in the early stage of iterative optimization is greater than that in the later stage of iterative optimization, so as to improve the early global search capability and the later local search capability.

10. A submarine cable laying path planning system with full risk avoidance, the system being an electronic device or a non-transitory computer-readable storage medium; The electronic device comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the steps of the submarine cable laying path planning method with full risk avoidance as described in any one of claims 1 to 9 are implemented. The non-transitory computer-readable storage medium stores a computer program thereon, wherein the computer program, when executed by a processor, implements the steps of the method for planning a submarine cable laying path with full risk avoidance as claimed in any one of claims 1 to 9.

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