A method and device for evaluating the safety of a fan tower structure based on pile-soil coupling

Abstract

The application discloses a kind of based on pile soil coupling's fan tower structure safety evaluation method and equipment, belong to offshore fan operation technology field.The application of a kind of based on pile soil coupling's fan tower structure safety evaluation method, by constructing fan monitoring model, fan load simulation model, tower response calculation model, monitoring data are handled, obtain the load that fan bears;Again using soil spring algorithm and shell element simulation algorithm, simulate the response of tower under the action of the load that fan bears, so that simulation model is closer to real scene, effectively avoid the error caused by excessive simplification, improve simulation precision and evaluation result.Further, the application can analyze the source of fan load, and accurately calculate the fan load, so that the uneven distribution of load and stress on the local section of fan tower can be fully considered, so that the fan load can be accurately simulated, and the evaluation of offshore fan tower is more accurate.

Description

TECHNICAL FIELD

[0001] The present application relates to a pile-soil coupling-based safety evaluation method and device for a wind turbine tower structure, and belongs to the technical field of offshore wind turbine operation and maintenance. BACKGROUND

[0002] With the rapid development of the offshore wind power industry, the operation and maintenance of offshore wind farms has become particularly important. The stability, reliability, and long-term performance of offshore wind turbine towers, as one of the core structures of wind turbine generators, directly affect the power generation efficiency and economy of the entire wind farm. Due to the complexity of the offshore environment, the stress and fatigue of the wind turbine tower during operation need to be effectively monitored and evaluated.

[0003] Traditional offshore wind turbine tower operation and maintenance relies on periodic manual inspection and offshore inspection, which has many limitations, such as high inspection cost, inflexible time, and inability to monitor potential problems in real time. With the continuous development of technology, operation and maintenance methods based on digital simulation and intelligent monitoring systems have gradually become a research and application hotspot.

[0004] Chinese patent application (CN118862562A) discloses a fatigue calculation method for local structure time-domain full coupling of offshore wind power single pile foundation, which simplifies the tower and pile into a truss structure, and then performs pile-soil coupling calculation through the interaction of nonlinear soil springs and the truss. Then, the results of the truss calculation are extracted for fatigue calculation.

[0005] However, for the offshore wind turbine tower scenario, the structure is a complex shell structure, and direct simplification into a truss structure will result in a large difference between the simulation model and the real scene, affecting the simulation accuracy and evaluation results.

[0006] Further, Chinese patent (CN118586091B) discloses a fatigue analysis method and system for offshore wind power foundation based on pile-soil coupling simulation. Since it is mainly used for design scenarios, to quickly complete simulation analysis and accelerate iterative design, the simulation model of this scheme uses one-dimensional beam elements. Therefore, for the offshore wind turbine tower scenario, the complex shell structure is directly simplified into one-dimensional beam elements, which still results in a large difference between the simulation model and the real scene, affecting the simulation effect.

[0007] Furthermore, the above two schemes and existing schemes do not consider the uneven distribution of loads and stresses on the local cross-section of the wind turbine tower, which leads to inaccurate simulation of wind turbine loads, affecting the accuracy of offshore wind turbine tower evaluation, and further unable to accurately predict the failure risk of the wind turbine tower, resulting in low efficiency of offshore wind turbine tower operation and maintenance, and affecting the service life of the equipment.

[0008] The information disclosed in this background section is only for understanding the background of the inventive concept, and therefore may include information that does not constitute prior art. Summary of the Invention

[0009] To address the aforementioned problems or one of them, the present invention aims to provide a method and device for safety assessment of wind turbine tower structures based on pile-soil coupling. By constructing a wind turbine monitoring model, a wind turbine load simulation model, and a tower response calculation model, the monitoring data is processed to obtain the load borne by the wind turbine. Then, using the soil spring algorithm and shell element simulation algorithm, the response of the tower under the load borne by the wind turbine is simulated, thereby enabling an accurate assessment of the structural safety of the tower and improving simulation accuracy and operation and maintenance efficiency.

[0010] To address the aforementioned problems or one of the aforementioned problems, the second objective of this invention is to provide a method and device for safety assessment of wind turbine tower structures based on pile-soil coupling. By establishing a tower response calculation model, considering the pile-soil coupling effect of offshore wind turbines, and accurately simulating the offshore wind turbine tower structure through a shell element simulation algorithm, the simulation model becomes closer to the real-world scenario, effectively avoiding errors caused by oversimplification, and improving simulation accuracy and assessment results.

[0011] To address the aforementioned problems, or one of them, the third objective of this invention is to provide a method and device for safety assessment of wind turbine tower structures based on pile-soil coupling. This method can analyze the sources of wind turbine loads and accurately calculate them, thereby fully considering the uneven distribution of loads and stresses on local cross-sections of the wind turbine tower. This allows for accurate simulation of wind turbine loads, making the assessment of offshore wind turbine towers more accurate. Furthermore, by combining this method with soil spring stiffness calculations, the mechanical calculations under real-world conditions are more comprehensive, better simulating the tower's stress under actual working conditions, ensuring the accuracy of the calculation results, and obtaining the tower's true response. This comprehensively reflects the complex situations encountered in actual operation and maintenance, helping maintenance personnel identify potential weaknesses.

[0012] To achieve one of the above objectives, the first technical solution of the present invention is as follows:

[0013] A safety assessment method for wind turbine tower structures based on pile-soil coupling includes the following steps:

[0014] Step 1: Collect monitoring data of offshore wind turbines using the previously created wind turbine monitoring model;

[0015] Step 2: Using the previously created wind turbine load simulation model, process the monitoring data to obtain the wind turbine load, which includes wind load and wind turbine operating load.

[0016] Step 3: Using the previously created tower response calculation model, the pile-soil coupling effect of the offshore wind turbine is considered, and the response of the tower under the load of the wind turbine is simulated through the soil spring algorithm and shell element simulation algorithm to obtain the displacement and stress distribution of the tower.

[0017] Step four: Using the previously created tower evaluation model, assess the structural safety of the tower based on its displacement and stress distribution, and obtain the evaluation results.

[0018] This invention constructs a wind turbine monitoring model, a wind turbine load simulation model, and a tower response calculation model to process monitoring data and obtain the load borne by the wind turbine. Then, it uses the soil spring algorithm and shell element simulation algorithm to simulate the tower response under the load borne by the wind turbine, thereby enabling an accurate assessment of the structural safety of the tower and improving simulation accuracy and operation and maintenance efficiency.

[0019] Furthermore, this invention establishes a tower response calculation model, considers the pile-soil coupling effect of the offshore wind turbine, and accurately simulates the offshore wind turbine tower structure through a shell element simulation algorithm. This makes the simulation model closer to the real-world scenario, effectively avoids errors caused by oversimplification, and improves simulation accuracy and evaluation results.

[0020] Furthermore, this invention establishes a wind turbine monitoring model and a wind turbine load simulation model to analyze the sources of wind turbine loads and accurately calculate them. This allows for full consideration of the uneven distribution of loads and stresses on local cross-sections of the wind turbine tower, thus enabling accurate simulation of wind turbine loads and making the assessment of offshore wind turbine towers more accurate. Combined with soil spring stiffness calculations, the mechanical calculations in a real-world environment are more comprehensive, better simulating the tower's stress under actual working conditions, ensuring the accuracy of the calculation results, and obtaining the tower's true response. This comprehensively reflects the complex situations encountered in actual operation and maintenance, helping maintenance personnel identify potential weaknesses. Simultaneously, by accessing real-time monitoring data from the wind turbine, a precise digital model is constructed, enabling real-time simulation of the tower's working state, predicting failure risks, thereby improving operation and maintenance efficiency, reducing the probability of failures, and extending equipment lifespan.

[0021] As a preferred technical measure:

[0022] Step one, the method for collecting monitoring data of offshore wind turbines using the previously created wind turbine monitoring model, is as follows:

[0023] Obtain scene information at the time to be monitored, including wind speed and wind direction;

[0024] Extract the actual measured information of the wind turbine by means of actual measurement or by querying recorded data, including the wind turbine operating power and wind turbine speed;

[0025] By summarizing the scene information and the actual measurement information of the wind turbine, the monitoring data of the offshore wind turbine is obtained.

[0026] As a preferred technical measure:

[0027] Step two: Using the previously created wind turbine load simulation model, the monitoring data is processed to obtain the method for determining the wind turbine's load capacity, as follows;

[0028] Acquire monitoring data, including wind speed, wind direction, fan operating power, and fan speed;

[0029] Based on the product specifications of the offshore wind turbine, the aerodynamic thrust coefficient, the swept area of ​​the turbine impeller blades, the blade length, and the cut-in and cut-out wind velocities were obtained.

[0030] Based on the fan power, fan speed and mechanical efficiency, calculate the fan operating load during the impeller operation process;

[0031] Based on the momentum blade element theory, as well as the aerodynamic thrust coefficient, air density, swept area, and fan operating power, the wind load at the top of the fan is calculated when it is operating at wind speed.

[0032] The leeward and windward sides of the tower are determined based on the positive and negative relationship between the wind direction angle and the cosine value of each node position.

[0033] Determine the direction of wind load application based on the leeward and windward sides.

[0034] The wind load and the wind turbine operating load are combined to obtain the load that the wind turbine bears.

[0035] As a preferred technical measure:

[0036] Step 3: Using the previously established tower response calculation model, considering the pile-soil coupling effect of the offshore wind turbine, and through the soil spring algorithm and shell element simulation algorithm, the tower response under the load of the wind turbine is simulated, and the displacement and stress distribution of the tower are obtained as follows:

[0037] Considering the pile-soil coupling effect of offshore wind turbines, a tower pile-soil coupling model is constructed based on the soil spring algorithm and shell element simulation algorithm.

[0038] The tower-pile-soil coupling model is used to simulate the interaction between the tower and the soil, reflecting the mechanical properties of the soil under different scour depths and displacement conditions.

[0039] The load borne by the wind turbine is input into the tower pile-soil coupling model, and static calculations are performed to obtain the soil spring position and soil spring stiffness variation curves with displacement.

[0040] Based on the soil spring position and the soil spring stiffness variation curve with displacement, the soil spring stiffness is updated and repeatedly calculated until convergence, thus obtaining the tower response data under the load of the wind turbine.

[0041] The displacement and stress distribution of the tower under the influence of soil scour depth were extracted from the response data.

[0042] As a preferred technical measure:

[0043] The method for constructing a tower pile-soil coupling model based on the soil spring algorithm is as follows:

[0044] Step 1: Based on the shell element simulation algorithm and according to the design data of the tower and pile pipe, a three-dimensional cylinder simulation object is established, and material properties are added to the three-dimensional cylinder simulation object; then, the three-dimensional cylinder simulation object is divided into shell elements to obtain tower shell elements and pile pipe shell elements with attribute information.

[0045] Step 2: Determine the spatial coordinates of the center of gravity and the total mass of the nacelle, hub, and blades, and set up the discrete units of the wind turbine at the spatial coordinates of the center of gravity;

[0046] Step 3: Based on the soil parameters in the geological survey report, the diameter and length of the pile pipe, and the soil scour depth in the wind farm pile foundation scour report, and based on the soil spring algorithm, calculate the anisotropic nonlinear stiffness curve and spatial coordinates of the soil spring; construct a discrete element of the soil spring at the spatial coordinates and set the initial spring stiffness.

[0047] Step 4: By using constraint equations, establish a synchronous constraint relationship between the discrete elements of the wind turbine and the tower shell elements, and at the same time establish a constraint relationship between the discrete elements of the soil spring and the pile shell elements, thereby obtaining the tower pile-soil coupling model.

[0048] As a preferred technical measure:

[0049] The method for obtaining tower shell elements and pile tube shell elements with attribute information is as follows:

[0050] Step 11, set up the shell element simulation algorithm, which includes the following:

[0051] For pile pipes, the actual scouring depth during operation and maintenance needs to be considered, and the pile pipes should be divided into the part above the mud surface and the part below the mud surface.

[0052] Since both the tower and the pile are thin-walled structures with diameters greater than their thicknesses, shell element meshes are used for modeling.

[0053] Meanwhile, to simplify the 3D cylinder simulation object, the flange connection between the tower and the pile pipe is ignored, and the tower and pile pipe meshes are connected using a common node method; the flange connection between different sections of the tower is also ignored, and the connection is also made using a common node method.

[0054] Since the length, diameter, and wall thickness of different sections of the tower and pile pipe will vary, the design data of the tower and pile pipe are used as input, with the length and diameter of each section of the tower or pile pipe as the input. On the Z-axis, with the origin as the initial point, the center point of each section of the tower is determined along the Z-axis according to the length of the tower. Then, a circle is drawn with each center point as the center and the pipe diameter as the diameter. Each circle is then laid out to form the tower model. Similarly, the center point of each section of the pile pipe is determined along the Z-axis, and after drawing a circle, it is laid out to obtain the pile pipe model.

[0055] Finally, the tower and pile pipe models are assembled to form a three-dimensional cylinder simulation object;

[0056] Step 12: By querying the design data of the tower structure and the pipe pile structure, determine the material properties of the tower and the pipe pile, including density, Young's modulus and Poisson's ratio; then add the material properties to the three-dimensional pipe simulation object to obtain a three-dimensional pipe simulation object with material properties.

[0057] Step 13: Based on the geometric characteristics of the tower and the pile pipe, perform mesh sensitivity analysis on the three-dimensional cylinder simulation object to obtain mesh density information;

[0058] Step 14: Based on the mesh density information, divide the three-dimensional cylinder simulation object into shell elements to obtain tower shell elements and pile shell elements with attribute information, and make the three-dimensional cylinder simulation object have different mesh densities.

[0059] As a preferred technical measure:

[0060] The method for constructing discrete elements for soil springs is as follows:

[0061] Step 21: Determine the soil stratification parameters by consulting the geological survey report of the wind field. The soil stratification parameters include soil elevation distribution, soil type, foundation reaction modulus, undrained shear strength, half-limit strength strain, internal friction angle, standard value of lateral limit friction, and pull-out coefficient.

[0062] Step 22: Based on the pile foundation scour report of the offshore wind farm, obtain the actual scour depth of the soil and correct the soil stratification parameters to obtain soil stratification information.

[0063] Step 23: Based on the soil layering information, each soil layer is equivalent to three types of soil springs in the lateral, axial and bending directions, and an end support soil spring capable of torsion and axial movement is added to the bottom of the pile pipe; then, according to the engineering specifications, the force position of each soil spring and the curve of soil spring stiffness changing with displacement are calculated.

[0064] The soil spring is located at the midpoint of each soil layer; the soil spring stiffness variation curve with displacement is constructed based on lateral force, foundation reaction modulus, soil spring depth, and soil layer lateral strength limit; the soil layer lateral strength limit is calculated based on undrained shear strength, buoyancy unit weight, and pile pipe outer diameter.

[0065] Step 24: Based on the position of the soil spring force and the curve of soil spring stiffness as a function of displacement, construct the discrete element of the soil spring.

[0066] As a preferred technical measure:

[0067] The wind turbine load is input into the tower pile-soil coupled model for static calculation. The soil spring stiffness is updated and the calculation is repeated until convergence, thus obtaining the tower response data under the wind turbine load.

[0068] Based on the soil spring position and the soil spring stiffness variation curve with displacement, the soil spring stiffness is updated and the calculation is repeated until convergence. The method for obtaining the tower response data under the load of the wind turbine is as follows:

[0069] Step 31: Perform static calculations based on the initial spring stiffness, extract the displacements of all soil springs, and calculate the new spring stiffness based on the curve of soil spring stiffness versus displacement.

[0070] Step 32: Apply the new soil spring stiffness value and combine it with the soil spring nodal force to perform static calculations and obtain the pile nodal displacement.

[0071] Step 33: Based on the piecewise linear force-displacement curves of each soil spring, check whether the tangential stiffness of the spring has changed under the current pile node displacement. If at least one spring has changed its tangential stiffness, update the pile tube stiffness matrix and re-solve the pile node displacement; otherwise, consider the calculation to be converged and proceed to step 34.

[0072] Step 34: Determine the tower's response data under the load of the wind turbine based on the pile node displacement.

[0073] As a preferred technical measure:

[0074] Step four: Using the previously created tower evaluation model, assess the structural safety of the tower based on its displacement and stress distribution. The method for obtaining the evaluation results is as follows:

[0075] Based on the displacement and stress distribution of the tower, draw displacement contour maps and stress contour maps;

[0076] Based on the displacement contour map, the maximum displacement of the tower is obtained;

[0077] Based on the stress cloud diagram, the maximum stress of the tower is obtained;

[0078] The maximum displacement of the tower is compared with the displacement limit value of the tower, and the comparison result is obtained as one.

[0079] The maximum stress of the tower is compared with the yield strength of the tower, resulting in comparison result two;

[0080] Based on comparison results one and two, the structural safety of the tower was assessed, and the assessment results were obtained, including the tower operating status as normal and the tower operating status as abnormal.

[0081] To achieve one of the above objectives, the second technical solution of the present invention is as follows:

[0082] A safety assessment device for wind turbine tower structures based on pile-soil coupling, comprising:

[0083] One or more processors;

[0084] Storage device for storing one or more programs;

[0085] When the one or more programs are executed by the one or more processors, the one or more processors implement the above-described method for safety assessment of wind turbine tower structures based on pile-soil coupling.

[0086] Compared with existing technical solutions, the present invention has the following beneficial effects:

[0087] This invention constructs a wind turbine monitoring model, a wind turbine load simulation model, and a tower response calculation model to process monitoring data and obtain the load borne by the wind turbine. Then, it uses the soil spring algorithm and shell element simulation algorithm to simulate the tower response under the load borne by the wind turbine, thereby enabling an accurate assessment of the structural safety of the tower and improving simulation accuracy and operation and maintenance efficiency.

[0088] Furthermore, this invention establishes a tower response calculation model, considers the pile-soil coupling effect of the offshore wind turbine, and accurately simulates the offshore wind turbine tower structure through a shell element simulation algorithm. This makes the simulation model closer to the real-world scenario, effectively avoids errors caused by oversimplification, and improves simulation accuracy and evaluation results.

[0089] Furthermore, this invention establishes a wind turbine monitoring model and a wind turbine load simulation model to analyze the sources of wind turbine loads and accurately calculate them. This allows for full consideration of the uneven distribution of loads and stresses on local cross-sections of the wind turbine tower, thus enabling accurate simulation of wind turbine loads and making the assessment of offshore wind turbine towers more accurate. Combined with soil spring stiffness calculations, the mechanical calculations in a real-world environment are more comprehensive, better simulating the tower's stress conditions under actual operating conditions, ensuring the accuracy of the calculation results, and obtaining the tower's true response. This comprehensively reflects the complex situations encountered in actual operation and maintenance, helping maintenance personnel identify potential weaknesses. Simultaneously, by accessing real-time monitoring data from the wind turbine, a precise digital model is constructed to simulate the tower's working state in real time, predicting failure risks, thereby improving operation and maintenance efficiency, reducing the probability of failures, and extending the equipment's service life. Attached Figure Description

[0090] Figure 1 This is a flowchart of a wind turbine tower structure safety assessment method according to the present invention;

[0091] Figure 2 This is another flowchart of the wind turbine tower structure safety assessment method of the present invention.

[0092] Figure 3 This is a schematic diagram of a discrete unit at the top of the tower according to the present invention;

[0093] Figure 4 This is a schematic diagram of a discrete element for the soil spring of the present invention;

[0094] Figure 5 This is a schematic diagram illustrating the application of wind load according to the present invention;

[0095] Figure 6 This is a schematic diagram of a grid in a specific embodiment of the present invention;

[0096] Figure 7 This is a tower displacement cloud diagram in a specific embodiment of the present invention;

[0097] Figure 8 This is a stress cloud diagram of the tower in a specific embodiment of the present invention. Detailed Implementation

[0098] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0099] Conversely, this invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of the invention as defined in the claims. Furthermore, to provide a better understanding of the invention, certain specific details are described in detail below. However, those skilled in the art will fully understand the invention even without these detailed descriptions.

[0100] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention.

[0101] like Figure 1 As shown, this is the first specific embodiment of the safety assessment method for wind turbine tower structures based on pile-soil coupling of the present invention:

[0102] A safety assessment method for wind turbine tower structures based on pile-soil coupling includes the following steps:

[0103] Step 1: Collect monitoring data of offshore wind turbines using the previously created wind turbine monitoring model;

[0104] Step 2: Using the previously created wind turbine load simulation model, process the wind turbine monitoring data to obtain the wind turbine load, which includes wind load and wind turbine operating load.

[0105] Step 3: Using the previously created tower response calculation model, the pile-soil coupling effect of the offshore wind turbine is considered, and the response of the tower under the load of the wind turbine is simulated through the soil spring algorithm and shell element simulation algorithm to obtain the displacement and stress distribution of the tower.

[0106] Step four: Using the previously created tower evaluation model, assess the structural safety of the tower based on its displacement and stress distribution, and obtain the evaluation results.

[0107] like Figure 2 As shown, this is the second specific embodiment of the safety assessment method for wind turbine tower structures based on pile-soil coupling of the present invention:

[0108] A safety assessment method for wind turbine tower structures based on pile-soil coupling includes the following steps:

[0109] Step 1: Based on the design drawings of the tower and pile pipe, and according to the length and diameter of each tower and pile pipe segment, automatically draw the 3D simulation object of the pipe using the modeling script and divide it into shell element meshes. Set the shell element properties according to the thickness of each tower and pile pipe segment. Define different material properties and input the material properties of the tower and pile pipe respectively. At the same time, determine the spatial coordinates of the center of gravity and the total mass of the nacelle, hub, and blades, set the discrete elements of the wind turbine at these spatial coordinates, and input the lumped mass.

[0110] Step 2: Based on the soil parameters in the geological survey report, the diameter and length of the pile pipe, and the soil scour depth in the wind farm pile foundation scour report, calculate the anisotropic nonlinear stiffness curve and spatial coordinates of the soil spring. Set up a discrete element for the soil spring at that spatial coordinate in the model and set the initial spring stiffness.

[0111] Step 3: Through constraint equations, establish a synchronous constraint relationship between the discrete element at the top of the tower and the tower shell element at the same height, and at the same time establish a constraint relationship between the discrete element of the soil spring and the pile shell element at the same height; obtain real-time monitoring data of the wind turbine through the wind turbine monitoring model, and apply wind load to the entire tower and wind turbine operation load to the discrete element of the wind turbine using the wind turbine load simulation model.

[0112] Step 4: Using the tower response calculation model, first perform static calculations to obtain the displacement of each soil spring. Substitute the displacement into the nonlinear stiffness curve of the soil spring to obtain the new spring stiffness. Then, perform static calculations again based on the new spring stiffness until the displacement of each soil spring converges.

[0113] Step 5: After the calculation converges, extract information such as the displacement and stress of the tower, and use the tower evaluation model to evaluate the structural safety of the tower.

[0114] This invention proposes a structural safety assessment method for wind turbine towers that considers pile-soil coupling and real-time monitoring data, enabling rapid real-time analysis of offshore wind turbine towers. It also presents a universal modeling tool for offshore wind turbine pile foundations and towers, capable of accurately modeling the piles and towers of monopile or high-pile cap offshore wind turbines based on wind turbine design drawings and wind farm geological survey reports. Furthermore, this invention accurately simulates the interaction between the offshore wind turbine piles and towers, providing precise assessments of the tower's health status under multiple operating conditions. The proposed simulation method can integrate real-time monitoring data from offshore wind turbine units as boundary conditions for finite element analysis, realistically displaying tower mechanical simulation results and identifying weak points, which is of significant importance for health monitoring and fault diagnosis during operation and maintenance.

[0115] A specific embodiment of applying this invention to perform offshore wind turbine tower analysis in an offshore wind farm:

[0116] An offshore wind farm has an average east-west length of approximately 9 km and a north-south width of 2–17 km. The center of the wind farm is about 20 km from the shore. The seabed topography within the farm area is relatively stable, with water depths ranging from 8 to 12 meters. The project will install 74 wind turbines, including 72 4.0MW turbines, 1 6.2MW turbine, and 1 7.0MW turbine, for a total installed capacity of 301.2MW. The wind turbines are arranged in three parallel rows, and the turbine foundations utilize a high-pile, high-base, and monopile structure.

[0117] In this embodiment, a 4MW wind turbine from the wind farm is selected. Its foundation is a monopile structure. The total mass of the top blades, hub, and nacelle of the tower is 431.1 tons. The total height of the tower is 79.23 meters, divided into 31 sections, with a bottom diameter of 6 meters and a top diameter of 4 meters. The total length of the pile pipe is 77.83 meters, divided into 15 sections, with a top diameter of 6 meters and a bottom diameter of 7.5 meters. According to the preliminary geological survey report, the soil in the area can be divided into 5 layers, mainly clay and silt. As of August 2024, the scour depth of the wind turbine pile foundation relative to the design elevation reached 8.38 meters. The wind turbine is equipped with wind direction and speed sensors, and can also output operating data such as rotational speed, enabling real-time extraction of environmental and wind turbine operating information.

[0118] According to the wind turbine tower structure safety assessment method proposed in this invention, which considers pile-soil coupling and real-time monitoring data, the deformation and stress state of the tower under normal operating conditions are analyzed to evaluate the tower's operational safety; specifically, it includes the following steps:

[0119] Step 1: Based on the design drawings of the tower and pile pipe, and according to the length and diameter of each tower and pile pipe segment, automatically draw the 3D simulation object of the tower and pile pipe using the modeling script and divide it into shell element meshes. Set the shell element properties according to the thickness of each tower and pile pipe segment. Define different material properties and add material properties for the tower and pile pipe respectively. At the same time, determine the spatial coordinates of the center of gravity and the total mass of the nacelle, hub, and blades, set the discrete elements of the wind turbine at these spatial coordinates, and input the lumped mass.

[0120] Step 2: Based on the soil parameters in the geological survey report, the diameter and length of the pile pipe, and the soil scour depth in the wind farm pile foundation scour report, calculate the anisotropic nonlinear stiffness curve and spatial coordinates of the soil spring. Set up a discrete element for the soil spring at that spatial coordinate in the model and set the initial spring stiffness.

[0121] Step 3: By using constraint equations, establish a degree-of-freedom constraint relationship between the discrete element at the top of the tower and the tower shell element at its height, and at the same time establish a degree-of-freedom constraint relationship between the discrete element of the soil spring and the pile shell element at its height; based on the real-time monitoring data of the wind turbine, apply wind load to the entire tower and apply wind turbine operating load to the discrete element of the wind turbine.

[0122] Step 4: First, perform static calculations to obtain the displacement of each soil spring. Substitute the displacement into the nonlinear stiffness curve of the soil spring to obtain the new spring stiffness. Then, perform static calculations again based on the new spring stiffness until the displacement of each soil spring converges.

[0123] Step 5: After the calculation converges, extract information such as the tower's displacement and stress for the safety structural evaluation of the tower.

[0124] Step one of this embodiment specifically includes the following steps:

[0125] The first step is to create a 3D simulation object of the tower and pile pipe based on the design drawings. Considering that the length, diameter, and wall thickness of different sections of the tower and pile pipe may vary, each section of the tower and pile pipe is defined separately. For the pile pipe, the distribution of the pile pipe above and below the mud surface is considered. Since both the tower and pile pipe are thin-walled structures, shell element models are used. Because the flange components are relatively small compared to the entire tower itself, the flange connection between the tower and pile pipe is ignored, and the tower and pile pipe meshes are connected using a common node method. At the same time, to simplify the 3D simulation object of the tower, the flange connection between different sections of the tower is ignored, and the connection is also made using a common node method. In this embodiment, the wind turbine foundation is a monopile structure. The total mass of the top blades, hub, and nacelle of the tower is 431.1 tons, the blade length is 73 meters, the total height of the tower is 79.23 meters, divided into 31 sections, with a bottom diameter of 6 meters and a top diameter of 4 meters. The total length of the pile pipe is 77.83 meters, divided into 15 sections, with a top diameter of 6 meters and a bottom diameter of 7.5 meters.

[0126] Based on the above information, in this embodiment, the modeling program uses the length and diameter of each tower or pile pipe segment as input. On the Z-axis, starting from the origin, the center point of each tower segment is determined along the +Z direction based on the tower length. Then, circles are drawn with each center point as the center and the pipe diameter as the diameter. Each circle is then laid out to form the tower model. Similarly, dividing the center point positions of pile pipe segments along the Z-direction yields the pile pipe model. The two models are then assembled to obtain the overall model.

[0127] The second step involves determining the material properties of the tower and pile structures, including density, Young's modulus, and Poisson's ratio, by consulting the tower structure design drawings and the steel pipe pile structure design drawings. These properties are then input into different groups of the model according to the design drawings.

[0128] According to relevant reports, the material properties of the tower and steel pipe pile structures are shown in Table 1.

[0129] Table 1 Material Parameters for Tower and Pipe

[0130] Material Designation Young's Modulus (GPa) Poisson's Ratio DH36 210 0.3 DH36-Z25 210 0.3 Q355NC 206 0.31 Q355ND 206 0.31

[0131] Enter the corresponding material properties according to the tower and pile pipe drawings.

[0132] The third step is to divide the grid according to the geometric characteristics of the tower and the pile pipe. Since the pile pipe usually contains a short section, it is necessary to divide it into sub-grids to make the overall grid more uniform. At the same time, a grid sensitivity analysis is performed, that is, the three-dimensional cylinder simulation object is divided into different grid densities, and the same set of working conditions is used as input to perform calculations. When the calculation results converge, the grid with the fewest nodes is selected to achieve better calculation efficiency while ensuring calculation accuracy.

[0133] like Figure 6 As shown, the mesh model has 8800 nodes, 2219 one-dimensional line elements, and 8760 two-dimensional quadrilateral surface elements, and is meshed using first-order elements. Mesh sensitivity verification and trial calculations prove that the mesh meets the finite element simulation requirements proposed in this invention.

[0134] The fourth step is to consult the wind turbine product manual to determine the total mass and center of gravity of the nacelle, hub, and blades, which is approximately 1 meter directly above the top of the tower. Figure 3 As shown, first, a node is established at this location, then it is set as a discrete element, and mass information, such as hub torque, wind turbine thrust, and other wind turbine operating loads, can be applied to this discrete element.

[0135] Step two in this embodiment specifically includes the following steps:

[0136] The first step is to determine the soil stratification by consulting the geological survey report of the wind farm. Key parameters to determine include soil layer elevation, soil type, foundation reaction modulus, undrained shear strength, half-limit strength strain, internal friction angle, lateral ultimate friction standard value, and pull-out coefficient. Based on the scour depth report of the offshore wind farm, the soil scour depth is obtained. Each soil layer is equivalent to three types of soil springs in the lateral, axial, and bending directions, and end-supported soil springs capable of torsion and axial movement are added at the pile bottom.

[0137] According to the engineering geological survey report of the sea area, there are 5 layers of soil within the scope of the pile pipe, and some relevant parameters are shown in Table 2.

[0138] Table 2. Soil Parameters

[0139]

[0140] Then, the location of each soil spring force and the force-displacement curve are calculated according to the American Petroleum Institute (API) or National Geotechnical Institute (NGI) specifications.

[0141] The soil spring is located in the middle of each soil layer, and the impact of erosion needs to be considered at this location.

[0142] According to the American Petroleum Institute (API) specifications, taking lateral soil springs as an example, the formulas for calculating the relationship between lateral force and displacement in each soil layer are as follows:

[0143]

[0144] Where p represents the lateral force, A is a constant, which can be taken as 0.9, k is the initial reaction modulus, and Z is the depth of the soil spring. u Let y be the lateral strength limit of the current soil layer, and y be the displacement. The specific calculation formula is as follows:

[0145] p u =3s u +γ ' z+Js u / D

[0146] Among them, s u γ represents the undrained shear strength, z represents the depth, and γ represents the shear strength. ' Where is the buoyant unit weight, D is the outer diameter of the pile pipe, and J is a constant, which can be taken as 0.25.

[0147] According to the nonlinear soil spring algorithm, four soil springs can be applied in this embodiment, with Z-axis coordinates of -41.56, -59.17, -68.35, and -77.83, respectively.

[0148] The second step is to determine the location of the soil spring based on the information obtained in the first step, such as... Figure 4 As shown, discrete elements are added to the model in step one, and a group of shell element nodes at the same height as the soil spring discrete element is obtained.

[0149] Step three specifically includes the following steps:

[0150] The first step is to establish synchronous constraint relationships between the discrete element at the top of the tower and the degrees of freedom of the tower shell elements at the same height through constraint equations. Simultaneously, this discrete point is input into the mass matrix to account for the effects of gravity.

[0151] According to the product manual, the total mass of the blades, hub, and nacelle is 431.1 tons, and this data is entered into the discrete unit.

[0152] The second step involves setting the degree-of-freedom relationship between the newly added soil spring discrete element and the pile foundation shell element node group at the same height in the second step of step two, and at the same time initializing the pile tube stiffness matrix according to the zero displacement stiffness of each soil spring.

[0153] The third step is to set the wind load and wind turbine operating load based on the real-time monitoring information of the wind turbine, and apply them to the tower and the discrete unit at the top of the tower.

[0154] Typical wind turbine monitoring information includes wind direction and wind speed. Therefore, in this invention, the wind load value is calculated using relevant formulas in the load specification. For the location where the wind load is applied, the windward and leeward sides of the tower are first determined based on the positive and negative relationship between the wind direction angle and the cosine value of each node location. The wind load is only applied to the windward side.

[0155] Given the wind turbine monitoring data at a certain moment, the wind speed is 20 m / s, the wind direction is 180 degrees, the wind turbine power is 4 MW, and the impeller speed is 12 rad / min, at this time, the wind speed can be applied to the windward surface using the load specifications as follows.

[0156] like Figure 5 As shown, since the area force of the wind load is the same on each shell element, the area force can be decomposed into the X and Y directions and applied separately in the global coordinate system.

[0157] For wind turbine operating loads, information such as wind turbine operating power and speed can be extracted from measured data. Key information such as power curves and thrust coefficient curves, blade swept area, blade length, and cut-in / cut-out wind velocities can be obtained from the offshore wind turbine product manual. The wind turbine operating loads can then be calculated using appropriate formulas.

[0158] After consulting the product manual, the aerodynamic thrust coefficient at this time is 0.097. According to the momentum blade element theory, the formula for calculating the aerodynamic load thrust at the top of the fan when operating at wind speed is as follows:

[0159]

[0160] In the formula, C F ρ is the aerodynamic thrust coefficient, A is the air density, V is the swept area of ​​the fan impeller, and V is the fan operating speed.

[0161] When the wind speed exceeds the cut-out wind speed, the wind turbine blades stop rotating. At this time, the aerodynamic thrust formula at the top of the tower is:

[0162]

[0163] In the formula, V s Where A is the maximum wind speed, B is the number of impellers, and A is the maximum wind speed. b This represents the projected area of ​​a single impeller in the wind turbine.

[0164] During impeller operation, torque is generated, at which point the mechanical efficiency is 0.9, calculated using the following formula:

[0165] M x =9550Pη / n=3.438×10 9 N·m

[0166] In the formula, P is the fan power, n is the impeller speed, and η is the mechanical efficiency.

[0167] Step four specifically includes the following steps:

[0168] The first step is to perform static calculations based on the initial spring stiffness from step two, extract the displacements of all soil springs, calculate the new spring stiffness according to the soil spring stiffness curve, and then reapply the new soil spring stiffness values ​​for static calculations. The calculation formula is as follows:

[0169]

[0170] Among them, U p K represents the displacement of the pile node. p F represents the pile stiffness matrix. p This represents the nodal force of the soil spring.

[0171] The second step is to check whether the tangential stiffness of the springs has changed under the current pile node displacement based on the piecewise linear force-displacement curve of each soil spring. If at least one spring has changed its tangential stiffness, update the pile tube stiffness matrix and resolve the pile node displacement; otherwise, the calculation is considered to have converged.

[0172] In step five, the simulation calculation results such as displacement and stress are extracted, and the stress condition of the tower is evaluated based on the magnitude of the stress and the tower yield stress.

[0173] Furthermore, to further increase the accuracy of the safety assessment, the tower tilt angle can be calculated using the formula in section 7.2.4 of GB50135-2019, as follows:

[0174] i = tanα = Δd / h

[0175] Where i is the tower tilt angle, α is the tower tilt angle, h is the tower height, and Δd is the deviation between the upper and lower centers of the tower.

[0176] Then, the safety assessment of the inclination of the all-steel tower is carried out in accordance with the requirements of 5.3.4 in GB50007-2011.

[0177] Based on the above steps, the displacement contour map obtained from the simulation is as follows: Figure 7 As shown, the stress cloud diagram is attached. Figure 8 As shown, the maximum displacement is 32 cm, and the tower tilt tangent is 0.004. When the height of the all-steel tower of the wind turbine is greater than 50 meters and less than or equal to 100 meters, the allowable tilt tangent is less than 0.005. At this time, the maximum stress of the tower is 80 MPa, which is less than the tower yield strength of 355 MPa. Therefore, the tower is operating normally under this condition.

[0178] In summary, this invention proposes a safety assessment method for wind turbine tower structures that considers pile-soil coupling and real-time monitoring data. Firstly, it is a rapid modeling method. Users only need to input the key geometric information of the tower and pile foundation to achieve accurate modeling of the pile pipe and tower of a monopile or high-pile cap offshore wind turbine.

[0179] Simultaneously, this invention utilizes nonlinear spring calculation formulas to determine the position and stiffness of the soil spring by incorporating scour depth and geological survey information, thus establishing the degree-of-freedom relationship between the soil spring and the pile-shell unit. This method improves calculation accuracy while effectively avoiding errors caused by oversimplification, resulting in a more realistic mechanical model.

[0180] Unlike traditional calculation methods, this invention employs an iterative method for soil spring stiffness, and in particular, conducts a detailed nonlinear analysis of the interaction between the soil and the pile tube. This method yields a more accurate soil spring stiffness, improves the adaptability and accuracy of the model, and thus more effectively reflects the interaction between the pile and the soil.

[0181] This invention also incorporates monitoring data such as wind turbine operating load, wind speed, and wind direction, combined with soil spring stiffness calculations, making the mechanical calculations in a real-world environment more comprehensive and better simulating the tower's stress conditions under actual operating conditions, thus ensuring the accuracy of the calculation results. This invention can better demonstrate the tower's actual response in detail, comprehensively reflect the complex situations encountered in actual operation and maintenance, and help maintenance personnel identify potential weaknesses.

[0182] An embodiment of a device applying the method of the present invention:

[0183] An electronic device comprising:

[0184] One or more processors;

[0185] Storage device for storing one or more programs;

[0186] When the one or more programs are executed by the one or more processors, the one or more processors implement the above-described method for safety assessment of wind turbine tower structures based on pile-soil coupling.

[0187] An embodiment of a computer medium applying the method of the present invention:

[0188] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-described method for safety assessment of wind turbine tower structures based on pile-soil coupling.

[0189] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application 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, optical storage, etc.) containing computer-usable program code.

[0190] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, as well as 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, create a machine for implementing the flowchart. Figure One One or more processes and / or boxes Figure One A device that provides the functions specified in one or more boxes.

[0191] 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 One One or more processes and / or boxes Figure One The function specified in one or more boxes.

[0192] 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 One One or more processes and / or boxes Figure One The steps of the function specified in one or more boxes.

[0193] The model in this application is an object that uses physical or virtual representation to objectively describe the form and structure. The object is not the same as a physical object, and is not limited to physical or virtual. It can be a data processing function, software program, processing mode, usage method, operation mode, workflow, application process, electronic hardware, circuit module, processing system, system imitation or simulation object.

[0194] 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 it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still modify or make equivalent substitutions to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A method for safety assessment of wind turbine tower structures based on pile-soil coupling, characterized in that: Includes the following steps: Step 1: Collect monitoring data of offshore wind turbines using the previously created wind turbine monitoring model; Step 2: Using the previously created wind turbine load simulation model, process the monitoring data to obtain the wind turbine load, which includes wind load and wind turbine operating load. Step 3: Using the previously created tower response calculation model, the pile-soil coupling effect of the offshore wind turbine is considered, and the response of the tower under the load of the wind turbine is simulated through the soil spring algorithm and shell element simulation algorithm to obtain the displacement and stress distribution of the tower. Step four: Using the previously created tower evaluation model, assess the structural safety of the tower based on its displacement and stress distribution, and obtain the evaluation results.

2. The method for safety assessment of wind turbine tower structures based on pile-soil coupling as described in claim 1, characterized in that: Step one, the method for collecting monitoring data of offshore wind turbines using the previously created wind turbine monitoring model, is as follows: Obtain scene information at the time to be monitored, including wind speed and wind direction; Extract the actual measured information of the wind turbine by means of actual measurement or by querying recorded data, including the wind turbine operating power and wind turbine speed; By summarizing the scene information and the actual measurement information of the wind turbine, the monitoring data of the offshore wind turbine is obtained.

3. The method for safety assessment of wind turbine tower structures based on pile-soil coupling as described in claim 1, characterized in that: Step two: Using the previously created wind turbine load simulation model, the monitoring data is processed to obtain the method for determining the wind turbine's load capacity, as follows; Acquire monitoring data, including wind speed, wind direction, fan operating power, and fan speed; Based on the product specifications of the offshore wind turbine, the aerodynamic thrust coefficient, the swept area of ​​the turbine impeller blades, the blade length, and the cut-in and cut-out wind velocities were obtained. Based on the fan power, fan speed and mechanical efficiency, calculate the fan operating load during the impeller operation process; Based on the momentum blade element theory, as well as the aerodynamic thrust coefficient, air density, swept area, and fan operating power, the wind load at the top of the fan is calculated when it is operating at wind speed. The leeward and windward sides of the tower are determined based on the positive and negative relationship between the wind direction angle and the cosine value of each node position. Determine the direction of wind load application based on the leeward and windward sides. The wind load and the wind turbine operating load are combined to obtain the load that the wind turbine bears.

4. The method for safety assessment of wind turbine tower structures based on pile-soil coupling as described in claim 1, characterized in that: Step 3: Using the previously established tower response calculation model, considering the pile-soil coupling effect of the offshore wind turbine, and through the soil spring algorithm and shell element simulation algorithm, the tower response under the load of the wind turbine is simulated, and the displacement and stress distribution of the tower are obtained as follows: Considering the pile-soil coupling effect of offshore wind turbines, a tower pile-soil coupling model is constructed based on the soil spring algorithm and shell element simulation algorithm. The tower-pile-soil coupling model is used to simulate the interaction between the tower and the soil, reflecting the mechanical properties of the soil under different scour depths and displacement conditions. The load borne by the wind turbine is input into the tower pile-soil coupling model, and static calculations are performed to obtain the soil spring position and soil spring stiffness variation curves with displacement. Based on the soil spring position and the soil spring stiffness variation curve with displacement, the soil spring stiffness is updated and repeatedly calculated until convergence, thus obtaining the tower response data under the load of the wind turbine. The displacement and stress distribution of the tower under the influence of soil scour depth were extracted from the response data.

5. The method for safety assessment of wind turbine tower structures based on pile-soil coupling as described in claim 4, characterized in that: The method for constructing a tower pile-soil coupling model based on the soil spring algorithm is as follows: Step 1: Based on the shell element simulation algorithm and according to the design data of the tower and pile pipe, a three-dimensional cylinder simulation object is established, and material properties are added to the three-dimensional cylinder simulation object; then, the three-dimensional cylinder simulation object is divided into shell elements to obtain tower shell elements and pile pipe shell elements with attribute information. Step 2: Determine the spatial coordinates of the center of gravity and the total mass of the nacelle, hub, and blades, and set up the discrete units of the wind turbine at the spatial coordinates of the center of gravity; Step 3: Based on the soil parameters in the geological survey report, the diameter and length of the pile pipe, and the soil scour depth in the wind farm pile foundation scour report, and based on the soil spring algorithm, calculate the anisotropic nonlinear stiffness curve and spatial coordinates of the soil spring; construct a discrete element of the soil spring at the spatial coordinates and set the initial spring stiffness. Step 4: By using constraint equations, establish a synchronous constraint relationship between the discrete elements of the wind turbine and the tower shell elements, and at the same time establish a constraint relationship between the discrete elements of the soil spring and the pile shell elements, thereby obtaining the tower pile-soil coupling model.

6. The method for safety assessment of wind turbine tower structures based on pile-soil coupling as described in claim 5, characterized in that: The method for obtaining tower shell elements and pile tube shell elements with attribute information is as follows: Step 11, set up the shell element simulation algorithm, which includes the following: For pile pipes, the actual scouring depth during operation and maintenance needs to be considered, and the pile pipes should be divided into the part above the mud surface and the part below the mud surface. Since both the tower and the pile are thin-walled structures with diameters greater than their thicknesses, shell element meshes are used for modeling. Meanwhile, to simplify the 3D cylinder simulation object, the flange connection between the tower and the pile pipe is ignored, and the tower and pile pipe meshes are connected using a common node method; the flange connection between different sections of the tower is also ignored, and the connection is also made using a common node method. Since the length, diameter, and wall thickness of different sections of the tower and pile pipe will vary, the design data of the tower and pile pipe are used as input, with the length and diameter of each section of the tower or pile pipe as the input. On the Z-axis, with the origin as the initial point, the center point of each section of the tower is determined along the Z-axis according to the length of the tower. Then, a circle is drawn with each center point as the center and the pipe diameter as the diameter. Each circle is then laid out to form the tower model. Similarly, the center point of each section of the pile pipe is determined along the Z-axis, and after drawing a circle, it is laid out to obtain the pile pipe model. Finally, the tower and pile pipe models are assembled to form a three-dimensional cylinder simulation object; Step 12: By querying the design data of the tower structure and the pipe pile structure, determine the material properties of the tower and the pipe pile, including density, Young's modulus and Poisson's ratio; then add the material properties to the three-dimensional pipe simulation object to obtain a three-dimensional pipe simulation object with material properties. Step 13: Based on the geometric characteristics of the tower and the pile pipe, perform mesh sensitivity analysis on the three-dimensional cylinder simulation object to obtain mesh density information; Step 14: Based on the mesh density information, divide the three-dimensional cylinder simulation object into shell elements to obtain tower shell elements and pile shell elements with attribute information, and make the three-dimensional cylinder simulation object have different mesh densities.

7. The method for safety assessment of wind turbine tower structures based on pile-soil coupling as described in claim 5, characterized in that: The method for constructing discrete elements for soil springs is as follows: Step 21: Determine the soil stratification parameters by consulting the geological survey report of the wind field. The soil stratification parameters include soil elevation distribution, soil type, foundation reaction modulus, undrained shear strength, half-limit strength strain, internal friction angle, standard value of lateral limit friction, and pull-out coefficient. Step 22: Based on the pile foundation scour report of the offshore wind farm, obtain the actual scour depth of the soil and correct the soil stratification parameters to obtain soil stratification information. Step 23: Based on the soil layering information, each soil layer is equivalent to three types of soil springs in the lateral, axial and bending directions, and an end support soil spring capable of torsion and axial movement is added to the bottom of the pile pipe; then, according to the engineering specifications, the force position of each soil spring and the curve of soil spring stiffness changing with displacement are calculated. The soil spring is located at the midpoint of each soil layer; the soil spring stiffness variation curve with displacement is constructed based on lateral force, foundation reaction modulus, soil spring depth, and soil layer lateral strength limit; the soil layer lateral strength limit is calculated based on undrained shear strength, buoyancy unit weight, and pile pipe outer diameter. Step 24: Based on the position of the soil spring force and the curve of soil spring stiffness as a function of displacement, construct the discrete element of the soil spring.

8. The method for safety assessment of wind turbine tower structures based on pile-soil coupling as described in claim 4, characterized in that: The load borne by the wind turbine is input into the tower pile-soil coupling model, static calculation is performed, the soil spring stiffness is updated and the calculation is repeated until convergence, and the response data of the tower under the load borne by the wind turbine is obtained. Based on the soil spring position and the soil spring stiffness variation curve with displacement, the soil spring stiffness is updated and the calculation is repeated until convergence. The method for obtaining the tower response data under the load of the wind turbine is as follows: Step 31: Perform static calculations based on the initial spring stiffness, extract the displacements of all soil springs, and calculate the new spring stiffness based on the curve of soil spring stiffness versus displacement. Step 32: Apply the new soil spring stiffness value and combine it with the soil spring nodal force to perform static calculations and obtain the pile nodal displacement. Step 33: Based on the piecewise linear force-displacement curves of each soil spring, check whether the tangential stiffness of the spring has changed under the current pile node displacement. If at least one spring has changed its tangential stiffness, update the pile tube stiffness matrix and re-solve the pile node displacement; otherwise, consider the calculation to be converged and proceed to step 34. Step 34: Determine the tower's response data under the load of the wind turbine based on the pile node displacement.

9. The method for safety assessment of wind turbine tower structures based on pile-soil coupling as described in claim 1, characterized in that: Step four: Using the previously created tower evaluation model, assess the structural safety of the tower based on its displacement and stress distribution. The method for obtaining the evaluation results is as follows: Based on the displacement and stress distribution of the tower, draw displacement contour maps and stress contour maps; Based on the displacement contour map, the maximum displacement of the tower is obtained; Based on the stress cloud diagram, the maximum stress of the tower is obtained; The maximum displacement of the tower is compared with the displacement limit value of the tower, and the comparison result is obtained as one. The maximum stress of the tower is compared with the yield strength of the tower, resulting in comparison result two; Based on comparison results one and two, the structural safety of the tower was assessed, and the assessment results were obtained, including the tower operating status as normal and the tower operating status as abnormal.

10. A safety assessment device for wind turbine tower structures based on pile-soil coupling, characterized in that: It includes: One or more processors; Storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement a method for safety assessment of wind turbine tower structures based on pile-soil coupling as described in any one of claims 1-9.

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