An integrated design analysis method for an offshore wind turbine and its foundation

Abstract

The application provides an integrated design analysis method for offshore wind turbine and foundation, comprising the following steps: first, designing offshore wind foundation according to geological data and environmental load; second, simulating offshore wind foundation; third, verifying the standardization of offshore wind foundation design and optimizing; fourth, calculating the stiffness matrix of the pile foundation mud surface when the offshore wind foundation design meets the requirements; fifth, combining the offshore wind foundation design scheme with the wind turbine upper structure design scheme and performing static force analysis on the wind turbine upper structure; sixth, performing modal analysis on the whole machine structure; seventh, judging whether the whole machine structure meets the offshore wind turbine structure design specification, and if not, re-optimizing the design until a compliant design scheme is obtained; eighth, outputting the compliant design scheme. Compared with the prior art, the application breaks the situation of mutual separation of geotechnical and structural analysis, and achieves the integrated analysis target of offshore wind structure.

Description

Technical Field

[0001] This invention relates to the field of offshore wind power structure and offshore foundation design technology, specifically to an integrated design and analysis method for offshore wind turbine units and their foundations. Background Technology

[0002] In the field of offshore wind power structure and offshore foundation design technology, ensuring the stability of offshore wind turbines and their foundations is not only the lifeline for resisting harsh marine environments and ensuring the safe operation of the units, but also the core cornerstone that determines the investment return and success or failure of the project throughout its entire life cycle. However, complex and ever-changing marine conditions—including extreme wind loads caused by strong typhoons, the impact of irregular waves, the continuous scouring of ocean currents, and the impact of sea ice—often have a severe nonlinear effect on the dynamic response of the structure, seriously threatening the long-term stability of the structure. Therefore, it is particularly important to carry out precise and systematic structural design for offshore wind turbines and their foundations.

[0003] However, existing structural design methods for offshore wind turbines and their foundations have the following shortcomings. Specifically, these methods often rely on multiple independent specialized software programs for step-by-step analysis: on the one hand, specialized geotechnical software such as FLAC3D is needed to simulate the interaction between the foundation and the ground to obtain boundary conditions; on the other hand, general-purpose structural software such as SESAM and ANSYS must be used to analyze the superstructure of the offshore wind turbine and its foundation. This traditional approach leads to the isolation of geotechnical and structural analysis systems, creating high barriers to data exchange, thus making it difficult to accurately and conveniently design the structure of offshore wind turbines and their foundations. Summary of the Invention

[0004] The purpose of this invention is to provide an integrated design and analysis method for offshore wind turbines and their foundations. To achieve this purpose, this invention employs the following technical solutions:

[0005] An integrated design and analysis method for offshore wind turbine units and their foundations includes the following steps:

[0006] S1. Preliminary Design Scheme for Offshore Wind Power Foundation: Based on the geological drilling data, static penetration test results, and geotechnical laboratory test results obtained from the geological survey of the wind farm site, and considering the wind turbine load, wind load, wave current load, and sea ice load that the offshore wind power project also needs to bear, the most unfavorable load combination is determined according to the "Load Code for Offshore Wind Farm Engineering Buildings (Structures)" and related design codes. The horizontal load Fx', vertical load Fz', overturning moment Myy' about the Y-axis, and torque Mzz' about the Z-axis under the most unfavorable load combination are calculated. Based on this, the structure of the offshore wind power foundation is designed in conjunction with the actual needs of the project and relevant design codes.

[0007] S2. Numerical Simulation of Offshore Wind Power Foundation: Based on the preliminary design scheme of offshore wind power foundation obtained in step S1, a ground-foundation coupled numerical model is established using FLAC3D software to study the deformation response characteristics, internal force distribution law, settlement and lateral deformation behavior of the foundation soil, as well as the generation form, development process and spatial distribution range of the plastic zone in the foundation under normal operating conditions and extreme operating conditions, so as to comprehensively evaluate the mechanical performance and stability of the offshore wind power foundation.

[0008] S3. Verification and optimization of offshore wind power foundation design scheme: Based on the mechanical performance analysis results of the offshore wind power foundation in step S2, evaluate whether the design scheme meets the design specifications. If it does not meet the design specifications, return to step S1 to adjust the design scheme of the offshore wind power foundation. Then, in step S2, calculate its mechanical performance. In step S3, evaluate whether the design scheme meets the design specifications based on the mechanical performance. Repeat this process until the offshore wind power foundation design fully meets the specification requirements.

[0009] S4. Stiffness matrix analysis of offshore wind power foundation: Under the condition that the offshore wind power foundation meets the specification requirements, the horizontal load Fx', vertical load Fz', overturning moment Myy' about the Y-axis and torque Mzz' about the Z-axis are applied to the offshore wind power foundation to calculate the corresponding deformation at a specified elevation (generally, this elevation is the mud surface elevation), and then the flexibility matrix and stiffness matrix at the mud surface of the pile foundation are calculated. At the same time, the design scheme of wind turbine and other superstructures is output.

[0010] S5. Establishment of the whole machine coupled model and static analysis: Combine the offshore wind power foundation design scheme, including the calculation results of the mud surface stiffness matrix, with the wind turbine superstructure design scheme, establish the finite element model of the structure above the foundation in the SESAM structural analysis software and perform static analysis on it to evaluate its structural deformation and internal forces under the design load.

[0011] S6. Modal and dynamic characteristic analysis of the whole machine: Based on the same whole machine structural model, modal analysis calculations are carried out to obtain the natural frequency, corresponding mode shape distribution and other relevant dynamic characteristic parameters of the structure at different orders, thereby assessing whether the structure is at risk of harmful resonance under external environmental loads such as waves and wind, and providing a basis for structural safety design and optimization.

[0012] S7. Verification and Iterative Optimization of Overall Structure: Based on the static and dynamic analysis results of steps S5 and S6, comprehensively determine whether the overall structure meets all the requirements of the offshore wind turbine structural design specifications. If the overall structure meets all the specifications, integrate all design parameters and analysis reports to form the final offshore wind turbine design scheme. If the overall structure does not meet all the specifications, return to the optimization stage. If the optimization direction is the upper structure of the wind turbine (such as adjusting the tower size and wall thickness), return to step S4 for re-analysis. If the optimization direction is the basic design scheme, return to step S1 for re-analysis until a fully compliant design scheme is obtained.

[0013] S8. Design Scheme Output: Output the complete offshore wind turbine design that meets the specifications.

[0014] Preferably, in step S2, when using FLAC3D software to establish a coupled numerical model of the foundation and soil to analyze the mechanical properties of the offshore wind power foundation, considering the weakening of the mechanical properties of the actual contact surface between the soil and the pile and the possible slippage effect of the interface during the actual stress process, 0.75 times the shear strength parameter of the adjacent soil is taken as the calculation basis for the pile-soil interface.

[0015] Compared with existing technologies, this invention has the following advantages: By introducing foundation-foundation coupled modeling and an integrated analysis process for the entire wind turbine, this invention effectively breaks the traditional disconnect between geotechnical analysis and structural analysis software systems, achieving the goal of truly integrated coupled analysis of the entire offshore wind turbine structure. In terms of structural design, this new analysis method significantly improves analysis accuracy, providing more precise and reliable data support for the design optimization of offshore wind turbine structures, thereby improving the overall quality of structural design. In terms of safety assessment, this new analysis method can more accurately evaluate the safety performance of offshore wind turbine structures under different operating conditions, identify potential safety hazards in advance, and provide a solid guarantee for the safe and stable operation of offshore wind power projects. Furthermore, in terms of structural service performance prediction, this new analysis method can better simulate the performance change trends of offshore wind turbine structures under long-term marine environmental loads, providing a scientific basis for formulating reasonable maintenance strategies. Attached Figure Description

[0016] Figure 1 This is a flowchart of an integrated design and analysis method for offshore wind turbines and their foundations according to the present invention.

[0017] Figure 2 This is the analytical model of the offshore wind power foundation of the present invention;

[0018] Figure 3 This is a schematic diagram of the overall structure of the present invention;

[0019] Figure 4This is the overall structural vibration mode diagram of the present invention. Detailed Implementation

[0020] The following is in conjunction with the appendix Figure 1-4 The embodiments of the present invention will be described in further detail below.

[0021] like Figure 1 As shown, an integrated design and analysis method for offshore wind turbines and their foundations includes the following steps:

[0022] S1. Preliminary Design Scheme for Offshore Wind Power Foundation: Based on the geological drilling data, static penetration test results, and geotechnical laboratory test results obtained from the geological survey of the wind farm site, and considering the wind turbine load, wind load, wave current load, and sea ice load that the offshore wind power project also needs to bear, the most unfavorable load combination is determined according to the "Load Code for Offshore Wind Farm Engineering Buildings (Structures)" and related design codes. The horizontal load Fx', vertical load Fz', overturning moment Myy' about the Y-axis, and torque Mzz' about the Z-axis under the most unfavorable load combination are calculated. Based on this, the structure of the offshore wind power foundation is designed in conjunction with the actual needs of the project and relevant design codes.

[0023] S2. Numerical simulation of offshore wind power foundation: Based on the preliminary design scheme of offshore wind power foundation obtained in step S1, a ground-foundation coupled numerical model is established using FLAC3D software to study the deformation response characteristics of offshore wind power foundation under normal operating conditions and extreme operating conditions.

[0024] S3. Verification and optimization of offshore wind power foundation design scheme: Based on the mechanical performance analysis results of the offshore wind power foundation in step S2, evaluate whether the design scheme meets the design specifications. If it does not meet the design specifications, return to step S1 to adjust the design scheme of the offshore wind power foundation. Then, in step S2, calculate its mechanical performance. In step S3, evaluate whether the design scheme meets the design specifications based on the mechanical performance. Repeat this process until the offshore wind power foundation design fully meets the specification requirements.

[0025] S4. Stiffness matrix analysis of offshore wind turbine foundation: Under the condition that the offshore wind turbine foundation meets the requirements of the specification, calculate the stiffness matrix at the mud surface of the pile foundation, and output the design scheme of wind turbine and other superstructures.

[0026] S5. Establishment of the whole machine coupled model and static analysis: Combine the offshore wind power foundation design scheme, including the calculation results of the mud surface stiffness matrix, with the wind turbine superstructure design scheme, establish the finite element model of the structure above the foundation in the SESAM structural analysis software and perform static analysis on it to evaluate its structural deformation and internal forces under the design load.

[0027] S6. Modal and dynamic characteristic analysis of the whole machine: Based on the same whole machine structural model, modal analysis calculations are carried out to obtain the natural frequency, corresponding mode shape distribution and other relevant dynamic characteristic parameters of the structure at different orders, thereby assessing whether the structure is at risk of harmful resonance under external environmental loads such as waves and wind, and providing a basis for structural safety design and optimization.

[0028] S7. Verification and Iterative Optimization of Overall Structure: Based on the static and dynamic analysis results of steps S5 and S6, comprehensively determine whether the overall structure meets all the requirements of the offshore wind turbine structural design specifications. If the overall structure meets all the specifications, integrate all design parameters and analysis reports to form the final offshore wind turbine design scheme. If the overall structure does not meet all the specifications, return to the optimization stage. If the optimization direction is the upper structure of the wind turbine (such as adjusting the tower size and wall thickness), return to step S4 for re-analysis. If the optimization direction is the basic design scheme, return to step S1 for re-analysis until a fully compliant design scheme is obtained.

[0029] S8. Design Scheme Output: Output the complete offshore wind turbine design that meets the specifications.

[0030] Example

[0031] Taking a certain offshore wind farm as an example, the center of the site is approximately 22.00 km from the shore, with water depths generally ranging from 14.00 m to 34.00 m. The initial plan is to install 100 wind turbines, each with a capacity of 12.0 MW, for a total installed capacity of 1200 MW. The wind power foundations are as follows... Figure 2 The following is the design process of a wind turbine structure and its four-bucket jacket foundation, as shown in the diagram:

[0032] Step 1: Based on the geological survey data of the wind farm site, the geological parameters at the turbine location are compiled, as shown in the table below:

[0033]

[0034] Based on the data provided by the wind turbine manufacturer, the wind turbine load is determined; based on long-term hydrological data, wave load is analyzed using the Morison equation or diffraction theory and considering dynamic response; based on ice condition parameters, ice load is analyzed using a compression failure model or a bending failure model; then, according to the "Load Code for Offshore Wind Farm Engineering Structures" and related design codes, the most unfavorable load combination is determined. The combined loads at the mud surface are detailed in the table below:

[0035]

[0036] Calculate the horizontal load Fx', vertical load Fz', overturning moment Myy' about the Y-axis, and torque Mzz' about the Z-axis based on the load at the mud surface under the most unfavorable load combination, where:

[0037] ;

[0038] ;

[0039] ;

[0040] ;

[0041] The results of calculating the horizontal load Fx', vertical load Fz', overturning moment Myy' about the Y-axis, and torque Mzz' about the Z-axis are shown in the table below:

[0042]

[0043] Based on the calculation results of horizontal load Fx', vertical load Fz', overturning moment Myy' about the Y-axis and torque Mzz' about the Z-axis, combined with the actual engineering requirements and relevant design specifications, the preliminary structure of the offshore wind power foundation is designed.

[0044] Step 2: Based on the preliminary design scheme of the offshore wind turbine foundation, a coupled numerical model of the foundation and soil is established using FLAC3D software. The deformation response characteristics, internal force distribution law, settlement and lateral deformation behavior of the foundation soil, as well as the generation form, development process and spatial distribution range of the intermediate plastic zone are studied under normal and extreme operating conditions. Generally speaking, under normal operating conditions, the mud surface rotation angle is required to be controlled within 4.36‰; under extreme operating conditions, the numerical analysis is required to converge and the plastic zone of the soil around the pile is not continuous.

[0045] Step 3: Evaluate whether the design scheme of the offshore wind power foundation meets the design specifications. If it does not meet the design specifications, return to Step 1 to adjust the design scheme of the offshore wind power foundation. Then, in Step 2, calculate its mechanical properties and evaluate whether the design scheme meets the design specifications again. Repeat this process until the offshore wind power foundation fully meets the requirements of the specifications.

[0046] Step 4: Assuming the offshore wind turbine foundation design meets the specifications, apply each load component individually to the single pile foundation and analyze its deformation response characteristics. Specifically, analyze the response caused by the horizontal load component Fx', including the horizontal displacement uFx and the rotation angle around the X-axis. Fx; the response induced by the vertical load component Fz', including displacement uFz along the Z-axis; and the response induced by the bending moment component Myy' about the Y-axis, including horizontal displacement uMyy and rotation about the Y-axis. Myy; the response induced by the torque component Mzz' about the Z-axis, including the torsional angle about the Z-axis. Mzz; The deformation feature results are shown in the table below:

[0047]

[0048] Based on the deformation characteristics of a single pile foundation under various load components, the components required to calculate the flexibility matrix are: fh, fv, fhr, fhr², fr, and ft. Substituting these into the flexibility matrix Flex yields:

[0049]

[0050] in, ; ; ; ; ; The result of the flexibility matrix Flex calculation is as follows:

[0051]

[0052] Based on the compliance matrix, according to the formula Solve for the stiffness matrix. The calculation result is:

[0053]

[0054] The design schemes for the fan and other superstructures are also provided.

[0055] Step 5: Calculate the results As boundary conditions at the bottom of the jacket, the large-scale marine engineering analysis software SESAM was used to model and analyze the four-bucket jacket foundation and the superstructure of the wind turbine. In accordance with current specifications, detailed calculations of vertical bearing capacity, structural strength checks, and deformation performance assessments were performed to ensure the reliability and safety of the overall design. The calculation results are shown in the table below:

[0056]

[0057] The calculation results show that the reliability and safety of the four-barrel jacket foundation and the upper structure of the wind turbine meet the requirements.

[0058] Step 6: Using SESAM to analyze the wind turbine generator set and its foundation, as shown in the figure. Figure 3 Modal analysis was performed on the overall system shown. The overall system includes blades, hub, nacelle, tower, foundation, and ground. The calculation results show that the modal analysis calculation model of the four-bucket jacket foundation and the upper wind turbine is as follows: Figure 4As shown in the table below, the first five frequencies of the modal analysis results of the four-bucket jacket foundation and the upper wind turbine are listed:

[0059]

[0060] According to the wind turbine manufacturer's requirements, the system's natural frequency must avoid the blade rotation frequency range (greater than 1.1 or less than 0.90). The wind turbine manufacturer provides an allowable frequency range of 0.182~0.20Hz for the entire unit. The above calculation results show that the first-order natural frequency of the overall jacket foundation system is 0.193Hz, which meets the wind turbine manufacturer's requirement for the first-order frequency.

[0061] Step 7: Based on the static and dynamic analysis results of Steps 5 and 6, comprehensively determine whether the overall structure meets all the requirements of the offshore wind turbine structural design specifications. If the overall structure meets all the specifications, integrate all design parameters and analysis reports to form the final offshore wind turbine design scheme. If the overall structure does not meet all the specifications, return to the optimization stage. If the optimization direction is the upper structure of the wind turbine (such as adjusting the tower size and wall thickness), return to Step 4 for re-analysis. If the optimization direction is the basic design scheme, return to Step 1 for re-analysis until a fully compliant design scheme is obtained.

[0062] Step 8: Output the final compliant offshore wind turbine design scheme.

[0063] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the concept of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An integrated design and analysis method for offshore wind turbine units and their foundations, characterized in that, Includes the following steps: S1. Preliminary Design Scheme for Offshore Wind Power Foundation: Based on the geological drilling data, static penetration test results, and geotechnical laboratory test results obtained from the geological survey of the wind farm site, and considering the wind turbine load, wind load, wave current load, and sea ice load that the offshore wind power project also needs to bear, the most unfavorable load combination is determined according to the "Load Code for Offshore Wind Farm Engineering Buildings (Structures)" and related design codes. The horizontal load Fx', vertical load Fz', overturning moment Myy' about the Y-axis, and torque Mzz' about the Z-axis under the most unfavorable load combination are calculated. Based on this, the structure of the offshore wind power foundation is designed in conjunction with the actual needs of the project and relevant design codes. S2. Numerical Simulation of Offshore Wind Power Foundation: Based on the preliminary design scheme of offshore wind power foundation obtained in step S1, a ground-foundation coupled numerical model is established using FLAC3D software to study the deformation response characteristics, internal force distribution law, settlement and lateral deformation behavior of the foundation soil, as well as the generation form, development process and spatial distribution range of the plastic zone in the foundation under normal operating conditions and extreme operating conditions, so as to comprehensively evaluate the mechanical performance and stability of the offshore wind power foundation. S3. Verification and optimization of offshore wind power foundation design scheme: Based on the mechanical performance analysis results of the offshore wind power foundation in step S2, evaluate whether the design scheme meets the design specifications. If it does not meet the design specifications, return to step S1 to adjust the design scheme of the offshore wind power foundation. Then, in step S2, calculate its mechanical performance. In step S3, evaluate whether the design scheme meets the design specifications based on the mechanical performance. Repeat this process until the offshore wind power foundation design fully meets the specification requirements. S4. Stiffness matrix analysis of offshore wind power foundation: Under the condition that the offshore wind power foundation meets the specification requirements, the horizontal load Fx', vertical load Fz', overturning moment Myy' about the Y-axis and torque Mzz' about the Z-axis are applied to the offshore wind power foundation to calculate the corresponding deformation at a specified elevation (generally, this elevation is the mud surface elevation), and then the flexibility matrix and stiffness matrix at the mud surface of the pile foundation are calculated. At the same time, the design scheme of wind turbine and other superstructures is output. S5. Establishment of the whole machine coupled model and static analysis: Combine the offshore wind power foundation design scheme, including the calculation results of the mud surface stiffness matrix, with the wind turbine superstructure design scheme, establish the finite element model of the structure above the foundation in the SESAM structural analysis software and perform static analysis on it to evaluate its structural deformation and internal forces under the design load. S6. Modal and dynamic characteristic analysis of the whole machine: Based on the same whole machine structural model, modal analysis calculations are carried out to obtain the natural frequency, corresponding mode shape distribution and other relevant dynamic characteristic parameters of the structure at different orders, thereby assessing whether the structure is at risk of harmful resonance under external environmental loads such as waves and wind, and providing a basis for structural safety design and optimization. S7. Verification and Iterative Optimization of Overall Structure: Based on the static and dynamic analysis results of steps S5 and S6, comprehensively determine whether the overall structure meets all the requirements of the offshore wind turbine structural design specifications. If the overall structure meets all the specifications, integrate all design parameters and analysis reports to form the final offshore wind turbine design scheme. If the overall structure does not meet all the specifications, return to the optimization stage. If the optimization direction is the upper structure of the wind turbine (such as adjusting the tower size and wall thickness), return to step S4 for re-analysis. If the optimization direction is the basic design scheme, return to step S1 for re-analysis until a fully compliant design scheme is obtained. S8. Design Scheme Output: Output the complete offshore wind turbine design that meets the specifications.

2. The integrated design and analysis method for offshore wind turbine units and their foundations according to claim 1, characterized in that: In step S2, when using FLAC3D software to establish a coupled numerical model of the foundation and soil to analyze the mechanical properties of the offshore wind power foundation, considering the weakening of the mechanical properties of the actual contact surface between the soil and the pile and the possible slippage effect of the interface during the actual stress process, 0.75 times the shear strength parameter of the adjacent soil is taken as the calculation basis for the pile-soil interface.

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