Method for establishing equivalent model of fan tower drum base

Abstract

The invention relates to the technical field of wind power generation, and discloses a fan tower base equivalent model building method which comprises three main steps of fan tower base local model building, equivalent boundary condition calculation, boundary condition application and calculation result checking. By means of the method, the calculation cost is greatly reduced, the efficiency is improved, the boundary rigidity is set in the local model of the fan tower drum base to accurately represent the constraint condition, and the method has the advantages that the calculation efficiency is improved. Meanwhile, six-direction acting force is applied to a cross brace and an inclined brace which are connected with the tower drum base, the boundary constraint rigidity value is obtained by extracting the deformation amount through back calculation, overall structure calculation does not need to be carried out in the whole process, the calculation amount can be greatly reduced, calculation time is shortened, and the technical problems that in the prior art, overall model calculation loads are large, and the analysis period is long are effectively solved.

Description

Technical Field

[0001] This invention relates to the field of wind power generation, and in particular to a method for establishing an equivalent model of a wind turbine tower base. Background Technology

[0002] With the rapid development of wind power technology, the development and utilization of offshore wind energy resources has gradually become an important direction in the wind power field. Especially in open sea areas with water depths exceeding 50 meters, floating platforms have been widely used as key facilities supporting wind turbines. In the overall design of a wind turbine, the tower base, as the main load-bearing structure, directly affects the turbine's operating efficiency and safety stability due to its design rationality and performance optimization. In actual marine environments, the tower structure must continuously withstand the combined effects of various complex environmental loads such as wind loads and wave loads. These loads create a complex stress on the top of the base, including vertical forces, lateral forces, and overturning moments. This complex stress state presents a significant challenge to accurately analyzing the structural response of the wind turbine tower base.

[0003] Patent application CN202410601455 discloses a tower design method for a floating wind turbine model. Combining the characteristic properties of the actual floating wind turbine tower, and considering factors such as geometric similarity, sensor matching, and aluminum profile selection, the method conducts iterative design by adjusting the structural parameters of the tower model. Ultimately, the first-order natural frequency of the model tower is scaled down to the target value of the designer and reaches the preset requirement.

[0004] The existing technology suffers from high computational load and long processing time, which not only severely reduces design efficiency but also results in a significant waste of computing resources, hindering the efficient advancement of optimization work.

[0005] Therefore, a new technical solution is needed to solve the above-mentioned technical problems. Summary of the Invention

[0006] The purpose of this invention is to provide a method for establishing an equivalent model of a wind turbine tower base, so as to construct a more accurate and reliable wind turbine tower base model, thereby providing support for the accurate evaluation of the mechanical characteristics of floating wind turbine systems and further assisting in the efficient optimization of floating wind turbine design schemes.

[0007] The technical solution adopted in this invention is: A method for establishing an equivalent model of a wind turbine tower base, characterized by the following steps: Step 1: Partial model construction of wind turbine tower base: Based on the structure itself, build the outer shell, internal reinforcements including horizontal beams and longitudinal stiffeners, and deck; Step 2: Calculation and application of equivalent boundary conditions: The connection between the local model of the wind turbine tower base and the overall structure is simplified to boundary constraint stiffness using the method of equivalent boundary stiffness. Six constraint stiffness values ​​are set at the connection positions between the local structure and each external structural component, including linear stiffness in three directions and angular stiffness in three directions. Step 3: Verification of calculation results: Apply identical wind turbine loads, such as aerodynamic loads and unit self-weight, to the top of the equivalent model of the wind turbine tower base and the top of the overall wind turbine model. Then extract the structural response data of the key units corresponding to the two models. By quantifying and comparing the consistency of the response results, the accuracy of the base equivalent model is verified.

[0008] By adopting the above structure, a more accurate and reliable wind turbine tower base model can be constructed, thereby providing support for the precise evaluation of the mechanical characteristics of floating wind turbine systems and further assisting in the efficient optimization of floating wind turbine design schemes.

[0009] Preferably, in step 1, the structural components involved are all thin-walled structures, which require the use of curved surfaces and shell elements for geometric and mesh simplification.

[0010] Preferably, in step 2, the connection structure with the local model of the wind turbine tower base includes horizontal bracing, diagonal bracing, and a vertical extension structure of the tower base.

[0011] Preferably, when establishing the model of the cross brace, one end of the member is fixed and constrained, and the other end is subjected to forces Fx, Fy, and Fz in three directions and moments Mx, My, and Mz in three directions. The applied load does not exceed the structural bearing capacity. The three linear stiffnesses and three angular stiffnesses are calculated by formula, where represents the deformation in the x, y, and z directions in the global coordinate system, and represents the angular changes around the three coordinate axes.

[0012] Preferably, the calculation formulas are as follows: .

[0013] Preferably, six stiffness values ​​are applied to the connection positions between the local model of the wind turbine tower base and the cross bracing members to obtain the constraint stiffness of all connection positions of the local model, thus completing the establishment of the equivalent model of the wind turbine tower base.

[0014] Preferably, in step 3, the accuracy of the calculation results of the wind turbine tower base equivalent model is verified by comparing the structural response of the local equivalent model and the overall model under the same working conditions.

[0015] By adopting the above structure, computational costs are significantly reduced and efficiency is improved: This method accurately characterizes constraints by setting boundary stiffness in the local model of the wind turbine tower base, while applying six-directional forces to the horizontal and diagonal braces connected to the tower base. The boundary constraint stiffness value is obtained by back-calculating the deformation. The entire process does not require overall structural calculations, which can significantly reduce the amount of computation and shorten the calculation time, effectively solving the technical pain points of large computational load and long analysis cycle of the overall model in the existing technology.

[0016] Compared with the prior art, the present invention has the following advantages: 1. The method of this invention is to construct a more accurate and reliable wind turbine tower base model, thereby providing support for the accurate evaluation of the mechanical characteristics of floating wind turbine systems and further assisting in the efficient optimization of floating wind turbine design schemes.

[0017] 2. The method of this invention significantly reduces computational costs and improves efficiency: This method sets boundary stiffness in the local model of the wind turbine tower base to accurately characterize the constraint conditions. At the same time, it applies six-directional forces to the horizontal and diagonal braces connected to the tower base. The boundary constraint stiffness value is obtained by extracting the deformation. The whole process does not require overall structural calculation, which can significantly reduce the amount of calculation and shorten the calculation time. It effectively solves the technical pain points of large overall model calculation load and long analysis cycle in the existing technology.

[0018] 3. The method of this invention ensures calculation accuracy and restores the real stress: By adopting the concept of equivalent model construction and performing equivalent boundary stiffness design on the local model, the actual stress state of the tower base in the overall wind turbine system can be accurately reproduced, significantly improving the accuracy of the calculation results. This design effectively overcomes the technical limitations of the prior art, which makes it difficult to accurately evaluate the stress characteristics of the overall structure when only based on local model analysis. Attached Figure Description

[0019] Figure 1 A flowchart for establishing the equivalent model of the wind turbine tower base of the present invention; Figure 2 This is a partial model of the wind turbine tower base and its connecting components to the overall structure of the present invention; Figure 3 This is an equivalent model of the wind turbine tower base of the present invention; Figure 4 This is a stress cloud diagram (unit: Pa) of the equivalent model of the wind turbine tower base under specific load conditions of the present invention. This figure should be shown in color. Figure 5 This is a stress cloud diagram (unit: Pa) of the wind turbine tower base in the overall wind turbine model under specific load conditions of the present invention. This figure needs to be illustrated in color.

[0020] The components are: 1. base; 2. cross brace; 3. extension section; 4. reinforcing material. Detailed Implementation

[0021] like Figure 1-5 As shown, a method for establishing an equivalent model of a wind turbine tower base includes three main steps: building a local model of the wind turbine tower base, calculating and applying equivalent boundary conditions, and verifying the calculation results. Detailed steps are as follows, and the flowchart is shown below. Figure 1 .

[0022] 1. Construction of a partial model of the wind turbine tower base The wind turbine tower base typically refers to the structural area where the wind turbine tower connects to the floating body. To improve the efficiency of iterative calculation and optimization of the local structure, the local structural optimization calculation model is usually selected from the connection position with the wind turbine tower flange to the first deck. For the calculation and analysis of this local model, in terms of the structure itself, it is necessary to establish the outer shell, internal reinforcements (including horizontal beams and longitudinal stiffeners), and deck. Since all the structural components involved are thin-walled structures, curved surfaces and shell elements can be used for geometric and mesh simplification.

[0023] 2. Calculation of equivalent boundary conditions and application of boundary conditions For the established local model of the wind turbine tower base, in order to ensure the equivalence between the local model and the global model, the key is that the boundary conditions applied to the local model can restore its boundary constraint state in the global model.

[0024] This patent uses the equivalent boundary stiffness method to simplify the connection between the local model of the wind turbine tower base and the overall structure into boundary constraint stiffness. Six constraint stiffness values ​​are set at the connection positions between the local structure and each external structural component, including linear stiffness in three directions and angular stiffness in three directions.

[0025] The connection structure with the local model of the wind turbine tower base includes, but is not limited to, horizontal bracing, diagonal bracing, and vertical extension structure of the tower base. Six stiffness calculations are performed on these connection structural components respectively. Taking the horizontal bracing member as an example, one end of the member is fixed and constrained, and the other end is subjected to forces Fx, Fy, Fz in three directions and moments Mx, My, Mz in three directions respectively. The applied load should not exceed the structural bearing capacity. The three linear stiffnesses and three angular stiffnesses are calculated by the following formulas (1)~(2). in These represent the deformations in the x, y, and z directions in the global coordinate system, respectively. The angle changes around the three coordinate axes are represented by the following formulas:

[0026] Six stiffness values ​​are applied to the connection points between the local model of the wind turbine tower base and the cross bracing members. By analogy, the constraint stiffness of all connection points in the local model is obtained, thus completing the establishment of the equivalent model of the wind turbine tower base.

[0027] 3. Verification of calculation results To verify the accuracy of the calculation results of the equivalent model of the wind turbine tower base, it can be achieved by "comparing the structural response of the local equivalent model and the overall model under the same working conditions": apply the same wind turbine load (such as aerodynamic load, unit self-weight, etc.) to the top of the equivalent model of the wind turbine tower base and the top of the overall wind turbine model, respectively. Then extract the structural response data of the key position units of the two models, and verify the accuracy of the base equivalent model by quantifying and comparing the consistency of the response results.

[0028] The following example, using the establishment of an equivalent model for a wind turbine tower base, illustrates in detail the implementation of this invention. Figure 2 The image shows a partial model of a wind turbine tower base and its connecting components to the overall structure. The selected section of the base 1 extends from the flange connecting the wind turbine tower to the bottom structure to the first deck. The interior of the base is reinforced with stiffener 4. The external connecting components of the partial model of the base include cross braces 2 and the bottom extension section 3 of the tower base.

[0029] like Figure 3 The equivalent model of the wind turbine tower base is shown, with only the central tower base 1 retained. The cross brace 2 is replaced by the equivalent boundary stiffness 5, and the bottom extension section is replaced by the equivalent boundary stiffness 6. Three forces and three moments in the global coordinate system are applied to the three cross braces and the bottom extension section respectively. The equivalent constraint stiffness at the corresponding positions is calculated by extracting the corresponding values ​​of the cross braces and the bottom extension section and combining them with formulas (1) and (2). The calculation results and process data of the equivalent constraint stiffness are shown in Table 1.

[0030] The calculated linear stiffness and three angular stiffness were applied to the connection points of the local model of the wind turbine tower with the three cross braces and the bottom extension section.

[0031] To verify the accuracy of the calculation results of the equivalent model of the wind turbine tower base, identical wind turbine loads were applied to the top of both the equivalent model of the wind turbine tower base and the top of the overall wind turbine model, as shown in Table 2. .

[0032] The structural response stress cloud diagrams of the key location elements corresponding to the two types of models are shown below. Figure 4 , Figure 5The maximum stress in the equivalent model of the wind turbine tower base is 161.13 MPa, and the maximum stress in the wind turbine tower base part of the overall model is 162.61 MPa. The calculation error is only 0.9%, which shows that the equivalent model of the wind turbine tower base established based on this method can accurately restore its boundary constraint state in the overall wind turbine structure.

[0033] Compared with existing technologies, the method for establishing an equivalent model of a wind turbine tower base provided by this invention significantly reduces computational costs and improves efficiency. This method accurately characterizes constraints by setting boundary stiffness in a local model of the wind turbine tower base, while simultaneously applying six-directional forces to the horizontal and diagonal braces connected to the tower base. The boundary constraint stiffness value is obtained by back-calculating the deformation. The entire process eliminates the need for overall structural calculations, significantly reducing computational load and time, effectively solving the technical pain points of high computational load and long analysis cycles in existing technologies. It also ensures computational accuracy and restores the true stress: This invention adopts an equivalent model construction approach, accurately reproducing the actual stress state of the tower base in the overall wind turbine system through equivalent boundary stiffness design of the local model, significantly improving the accuracy of the calculation results. This design effectively overcomes the technical limitations of existing technologies that struggle to accurately assess the overall structural stress characteristics when analyzing only local models.

[0034] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should be included within the scope of protection defined by the claims of the present invention.

Claims

1. A method for establishing an equivalent model of a wind turbine tower base, characterized in that: Includes the following steps: Step 1: Partial model construction of wind turbine tower base: Based on the structure itself, build the outer shell, internal reinforcements including horizontal beams and longitudinal stiffeners, and deck; Step 2: Calculation and application of equivalent boundary conditions: The connection between the local model of the wind turbine tower base and the overall structure is simplified to boundary constraint stiffness using the method of equivalent boundary stiffness. Six constraint stiffness values ​​are set at the connection positions between the local structure and each external structural component, including linear stiffness in three directions and angular stiffness in three directions. Step 3: Verification of calculation results: Apply identical wind turbine loads, such as aerodynamic loads and unit self-weight, to the top of the equivalent model of the wind turbine tower base and the top of the overall wind turbine model. Then extract the structural response data of the key units corresponding to the two models. By quantifying and comparing the consistency of the response results, the accuracy of the base equivalent model is verified.

2. The method for establishing an equivalent model of a wind turbine tower base according to claim 1, characterized in that: In step 1, the structural components involved are all thin-walled structures, which require the use of curved surfaces and shell elements for geometric and mesh simplification.

3. The method for establishing an equivalent model of a wind turbine tower base according to claim 1, characterized in that: In step 2, the connection structure with the local model of the wind turbine tower base includes horizontal bracing, diagonal bracing, and vertical extension structure of the tower base.

4. The method for establishing an equivalent model of a wind turbine tower base according to claim 3, characterized in that: When establishing the model of the cross brace, one end of the member is fixed and constrained, and forces Fx, Fy, and Fz in three directions and moments Mx, My, and Mz in three directions are applied to the other end. The applied load does not exceed the structural bearing capacity. The three linear stiffnesses and three angular stiffnesses are calculated using formulas. These represent the deformations in the x, y, and z directions in the global coordinate system, respectively. These represent the angular changes around the three coordinate axes.

5. The method for establishing an equivalent model of a wind turbine tower base according to claim 4, characterized in that: The calculation formulas are as follows: 。 6. The method for establishing an equivalent model of a wind turbine tower base according to claim 5, characterized in that: The six stiffness values ​​are applied to the connection positions between the local model of the wind turbine tower base and the cross bracing members to obtain the constraint stiffness of all connection positions of the local model, thus completing the establishment of the equivalent model of the wind turbine tower base.

7. The method for establishing an equivalent model of a wind turbine tower base according to claim 1, characterized in that: In step 3, the accuracy of the calculation results of the wind turbine tower base equivalent model is verified by comparing the structural response of the local equivalent model and the overall model under the same working conditions.

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