A Similarity Scaling Method for the Dynamic Characteristics of a Jacket Offshore Wind Turbine Structure

Abstract

The present invention discloses a method for dynamic characteristic similarity scaling of a jacket offshore wind turbine structure, belonging to the field of scaled model design. The method includes: simplifying and modeling the prototype structure of the target jacket offshore wind turbine into a scaled model of a space truss structure; preliminarily determining the cross-sectional diameter scaling coefficient of the hollow beam element according to the consistent cross-sectional area scaling coefficients of four types of hollow beam elements; subsequently calculating the thickness scaling coefficient of the hollow beam element and further calculating the thickness of the hollow beam element to complete the scaling calculation of the hollow beam element; keeping the aspect ratio of the length, width and height of the nacelle unchanged and making the mass scaling coefficient of the nacelle equal to the scaling coefficient of the hollow beam element to scale the nacelle element. The present invention is used for the design of a scaled model of a jacket offshore wind turbine. The constructed scaled model can maintain the similarity of structural dynamic characteristics with the prototype and can be used to meet the research requirements of the wind turbine structure performance evaluation in the design stage and the wind turbine structure health monitoring method in the operation stage.

Description

Technical Field

[0001] The present invention belongs to the field of scaled model design, and specifically relates to the experimental research of jacket-type offshore wind turbines, that is, a method for dynamically similar scaling of jacket offshore wind turbine structures. Background Art

[0002] Structural health monitoring is crucial for ensuring the long-term stable operation of jacket-type offshore wind turbines. Conventional structural health monitoring methods usually process data based on vibration signals to extract effective structural fault characteristics. However, due to the large volume and remote installation location of the jacket wind turbine prototype, on-site modal testing and vibration signal acquisition will incur high costs. Therefore, there is an urgent need to develop a scaled model of the jacket wind turbine with the same structural dynamic characteristics for research on structural health monitoring methods under laboratory conditions.

[0003] The basic principle of conventional scaled model design methods is the dimensional analysis theory. Such methods usually construct dimensionless constants based on the expressions of the physical characteristics of the concerned structural system, and achieve the consistency of the model and the prototype in the concerned characteristics by controlling the dimensionless constants to remain unchanged during the scaling process. Corresponding implementation cases include the Chinese invention patent with the publication number CN112036032A and the invention name of a scaled model design method for a high-rise RC frame structure, and the Chinese invention patent with the publication number CN116542040A and the invention name of a similarity scaling determination method for the impact vibration response of a complex thin plate structure. Such scaling methods can maintain the similarity of structural dynamic characteristics, but have strict requirements for the consistency of the scaling coefficients of each dimension of the structural shape. Since the conduit unit of the jacket offshore wind turbine is a large-size thin-wall structure with a thickness usually less than 30 mm, the unit wall thickness of the 1:100 large-scale scaled model designed by the dimensional analysis method will be less than 0.3 mm, making it difficult for the model in both processing and manufacturing and experiments. Therefore, such methods are not applicable to the scaled model design of jacket offshore wind turbines. The Chinese invention patent with the publication number CN112112771B and the invention name of a large-scale floating wind turbine scaled tower satisfying stiffness and mass similarity and its working method, and the Chinese invention patent with the publication number CN111680361A and the invention name of a scaled model design method for airships based on similarity theory start from the vibration theory and perform scaling calculations based on the mass and stiffness matrices of the structural system, but neither of them considers the scaling of the rotational stiffness and moment of inertia of the beam element, and cannot fully guarantee the similarity of the structural dynamic characteristics between the scaled model and the prototype. Summary of the Invention

[0004] The object of the present invention is to overcome the defects in the prior art and provide a method for dynamically scaling the characteristics of a jacket offshore wind turbine structure. The method of the present invention can maintain the similarity of the structural dynamic characteristics between the designed scaled model and the prototype, that is, the natural frequencies of each order are scaled by the same ratio, and the normalized mode shapes of each order are consistent. This method derives the relationship between the scaling coefficients of the cross-sectional thickness and diameter of the beam elements of the jacket, and can adaptively adjust the thickness scaling coefficient of the structural elements according to actual needs, relaxing the requirements for the processing accuracy of the jacket scaled model and expanding the feasibility of experimental research on jacket wind turbines.

[0005] The specific technical solution adopted by the present invention is as follows:

[0006] The present invention provides a method for dynamically scaling the characteristics of a jacket offshore wind turbine structure, which is as follows:

[0007] S1: Simplify and model the prototype structure of the target jacket offshore wind turbine into a scaled model of a space truss structure; the space truss structure includes a nacelle unit and four hollow beam elements with uniform thickness;

[0008] S2: In the scaled model, based on the consistent scaling coefficients of the cross-sectional areas of the four hollow beam elements, initially determine the scaling coefficient of the cross-sectional diameter of the hollow beam elements; subsequently, calculate the thickness scaling coefficient of the hollow beam elements based on the scaling coefficient of the cross-sectional diameter, and further calculate the thickness of the hollow beam elements to complete the scaling calculation of the hollow beam elements;

[0009] S3: In the scaled model, keep the ratio of the length, width, and height of the nacelle unchanged, and make the mass scaling coefficient of the nacelle equal to the scaling coefficient of the hollow beam elements to scale the nacelle unit.

[0010] Preferably, in S1, the four hollow beam elements are respectively a support member, a main leg, a diagonal brace member, and a tower barrel; several upper parts of the main legs are inclined inwardly, and the main legs are fixedly connected axially through several staggered support members; a vertical tower barrel is fixed to the top of all the main legs through diagonal brace members, and a nacelle is fixed to the top of the tower barrel;

[0011] In the scaled model, the length, cross-sectional diameter, and thickness of each hollow beam element are the same as those of the jacket offshore wind turbine prototype; the diagonal brace member is obtained by equivalent simplification of mass and stiffness based on the wind turbine transition platform; the nacelle is simplified into a cuboid hollow mass block, and its mass is equal to the sum of the masses of the nacelle and the blades in the original jacket offshore wind turbine.

[0012] Preferably, in the scaled model, the four hollow beam elements are regarded as undamped three-dimensional Euler-Bernoulli beams, and each hollow beam element contains a total of 12 degrees of freedom from 2 nodes.

[0013] Preferably, the cross-sectional area scaling coefficient is calculated based on the diameter scaling factor and the thickness scaling factor ; assuming that the diameter scaling factor , the thickness scaling factor and the ratio k of the thickness to the diameter in the prototype are known, then is equivalent to multiplied by the square of the proportionality coefficient; where the denominator of the proportionality coefficient is the result of subtracting 1 from the square of (1 minus 2 times the thickness-to-diameter ratio k), and the denominator is the result of subtracting 1 from the square of (1 minus the ratio of 2 times the thickness-to-diameter ratio k to the ratio of the thickness scaling factor to the diameter scaling factor . Specifically, it is expressed as the following formula:

[0014]

[0015] Preferably, the thickness scaling factor is calculated through the structural dynamic characteristic similarity conditional formula; assuming that the diameter scaling factor , the length scaling factor and the ratio k of the thickness to the diameter in the prototype are known, then is expressed in the form of a fraction, whose denominator is 2 times the thickness-to-diameter ratio k, and the numerator is the diameter scaling factor minus the square root of the subtraction of two terms. The first term is the square of the length scaling factor multiplied by (1 minus the square of 2 times the thickness-to-diameter ratio k plus 1), and the second term is the square of the diameter scaling factor . Specifically, it is expressed as the following formula:

[0016]

[0017] In a second aspect, the present invention provides a dynamic characteristic similarity scaling system for a jacket offshore wind turbine structure, including:

[0018] A scaling model construction module, configured to simplify and model the prototype structure of the target jacket offshore wind turbine into a scaling model of a space truss structure; the space truss structure includes a nacelle unit and four hollow beam units with uniform thickness;

[0019] A hollow beam unit scaling calculation module, configured to preliminarily determine the cross-sectional diameter scaling factor of the hollow beam unit in the scaling model according to the consistency of the cross-sectional area scaling factors of the four hollow beam units; subsequently, calculate the thickness scaling factor of the hollow beam unit based on the cross-sectional diameter scaling factor, and further calculate the thickness of the hollow beam unit to complete the scaling calculation of the hollow beam unit;

[0020] The nacelle unit scaling module is used to keep the ratio of the length, width and height of the nacelle unchanged in the scaled model, and make the mass scaling factor of the nacelle equal to the scaling factor of the hollow beam element, so as to scale the nacelle unit.

[0021] In a third aspect, the present invention provides a computer program product, including a computer program / instructions, which when executed by a processor, can implement the dynamic characteristic similarity scaling method of the jacket offshore wind turbine structure as described in any item of the first aspect.

[0022] In a fourth aspect, the present invention provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the dynamic characteristic similarity scaling method of the jacket offshore wind turbine structure as described in any item of the first aspect is implemented.

[0023] In a fifth aspect, the present invention provides a computer electronic device, including a memory and a processor;

[0024] The memory is used to store a computer program;

[0025] The processor is used to implement the dynamic characteristic similarity scaling method of the jacket offshore wind turbine structure as described in any item of the first aspect when executing the computer program.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention is used for the design of the scaled model of the jacket offshore wind turbine. The constructed scaled model can maintain the similarity of the structural dynamics characteristics with the prototype, that is, the natural frequencies of each order are scaled according to the same ratio, and the normalized mode shapes of each order are consistent. It can be used to meet the research needs of the wind turbine structure performance evaluation in the design stage and the wind turbine structure health monitoring method in the operation stage. Compared with other scaling methods, the present invention also provides an expression for the relationship between the cross-sectional thickness and diameter scaling factors of the jacket beam element, realizing the adaptive adjustment of the structural thickness scaling factor, effectively reducing the processing difficulty of the jacket dynamic characteristic similarity scaled model, and expanding the possibility of experimental research on the jacket wind turbine. Description of the Drawings

[0028] Figure 1 It is a schematic diagram of the simplified jacket offshore wind turbine structure (i.e., a space truss structure);

[0029] Figure 2 It is a schematic diagram of an Euler-Bernoulli beam element;

[0030] Figure 3 For the relationship curves of four kinds of hollow beam elements;

[0031] Figure 4For the four hollow beam elements Relationship curves;

[0032] In the figure, the reference numerals are: support member 1, main leg 2, diagonal brace 3, tower barrel 4, nacelle 5. Specific implementation manner

[0033] The present invention will be further described and illustrated below in conjunction with the accompanying drawings and specific implementation manners. The technical features of each implementation manner in the present invention can be combined correspondingly without conflict.

[0034] The present invention provides a method for dynamically scaling a jacket offshore wind turbine structure, and the method is as follows:

[0035] S1: Simplify and model the prototype structure of the target jacket offshore wind turbine into a scaled-down model of a space truss structure; wherein, the space truss structure includes a nacelle 5 unit and four hollow beam units with uniform thickness.

[0036] As a preferred embodiment of the present invention, as Figure 1 shown, the simplified space truss structure mainly includes a support member 1, a main leg 2, a diagonal brace 3, a tower barrel 4 and a nacelle 5. The upper parts of multiple main legs 2 are arranged obliquely inward, and the main legs 2 are fixedly connected along the axial direction by multiple support members 1 arranged in a staggered manner; a vertical tower barrel 4 is fixed to the top of all the main legs 2 through diagonal braces 3, and a nacelle 5 is fixed to the top of the tower barrel 4. The simplified prototype of the jacket offshore wind turbine in the figure includes four hollow circular cylindrical beam units with uniform thickness, namely a support member 1, a main leg 2, a diagonal brace 3 and a tower barrel 4. Among them, the diagonal brace 3 is obtained by equivalent simplification of mass and stiffness on the basis of the transition platform of the wind turbine. The length, cross-sectional diameter and thickness of each hollow beam unit are the same as those of the prototype of the jacket offshore wind turbine. Since the present invention mainly focuses on the support structure of the offshore wind turbine, the nacelle 5 is simplified into a cuboid mass block, and the inside is hollowed out so that the mass of the mass block is equal to the sum of the masses of the nacelle 5 and the blades in the original jacket offshore wind turbine.

[0037] S2: In the scaled-down model, according to the fact that the cross-sectional area scaling coefficients of the four hollow beam units are kept consistent, initially determine the cross-sectional diameter scaling coefficient of the hollow beam unit; then calculate the thickness scaling coefficient of the hollow beam unit on the basis of the cross-sectional diameter scaling coefficient, and further calculate the thickness of the hollow beam unit to complete the scaling calculation of the hollow beam unit.

[0038] As a preferred embodiment of the present invention, the derivation process of this step is as follows:

[0039] S21: Regard the four hollow beam units as undamped three-dimensional Euler-Bernoulli beams, and each hollow beam unit contains a total of 12 degrees of freedom from 2 nodes, as Figure 2 shown. The displacement matrix expression of each degree of freedom of the node in the local coordinate system is:

[0040]

[0041] Among them, corresponds to the tensile-compressive degree of freedom in the axial direction, corresponds to the bending degree of freedom in the xoy plane, corresponds to the bending degree of freedom in the xoz plane, corresponds to the rotational degree of freedom about the axial direction; x, y, and z respectively refer to the displacement distances along the x-axis, y-axis, and z-axis, the superscripts 1 and 2 respectively refer to the two nodes in the hollow beam element, and the subscripts y and z respectively refer to the two rotational directions about the y-axis and x-axis;

[0042] The expression of the stiffness matrix of the hollow beam corresponding to this displacement matrix is:

[0043]

[0044] Among them,

[0045]

[0046] are respectively the stiffness matrices on the tensile-compressive, bending in the xoy plane, bending in the xoz plane, and torsional about the axis degrees of freedom of the hollow beam, and E, G, A, l, I, I p respectively represent the Young's modulus of the material of the hollow beam, the shear modulus, the cross-sectional area of the hollow beam element, the length, the moment of inertia of the cross-section, and the polar moment of inertia of the cross-section;

[0047] The expressions of the scaling coefficients of the elements in the stiffness matrix are:

[0048]

[0049] Among them is the scaling operation, representing the ratio of the magnitude of a certain physical quantity in the scaled model to its magnitude in the prototype, is the element in the tensile-compressive stiffness matrix, , and respectively represent three types of elements with different dimensions in the bending stiffness matrix, represents the element in the torsional stiffness matrix. Based on the structural vibration expression and the dimensional conservation relationship, the expressions of the scaling coefficients of the elements in the corresponding mass matrix can be obtained:

[0050]

[0051] Among them, represents the density of the material used, represents the moment of inertia about the axis of the hollow beam element, is the element in the tensile-compressive mass matrix, , and respectively represent three types of elements with different dimensions in the bending mass matrix, represents the element in the torsional mass matrix.

[0052] S22: By multiplying or dividing by the length l simultaneously, ensure that all elements in the mass matrix of each hollow beam element in the local coordinate system have consistent dimensions and all elements in the stiffness matrix have consistent dimensions. Let the dimension of the elements in the mass matrix be M, and the dimension of the elements in the stiffness matrix be MT -2 , then the expression of the element scaling factors for the two is further rewritten as:

[0053]

[0054] .

[0055] S23: According to the finite element method, during the assembly of each hollow beam element into the jacket offshore wind turbine, first transform the mass matrix and stiffness matrix of each hollow beam element in the local coordinate system to be represented in the global coordinate system through coordinate transformation. The global transformation expressions are:

[0056]

[0057] where and are the stiffness matrix and mass matrix of the hollow beam element in the global coordinates, and are the stiffness matrix and mass matrix of the hollow beam element in the local coordinate system, is the coordinate transformation matrix from the local coordinate system to the global coordinate system;

[0058] Subsequently, sum the mass matrix and stiffness matrix of each hollow beam element in the global coordinate system to obtain the mass matrix and stiffness matrix of the overall structure of the jacket offshore wind turbine. Specifically, the overall structure mass matrix and stiffness matrix of the jacket offshore wind turbine can be obtained by summing the mass matrix and stiffness matrix of each sub-element c:

[0059]

[0060] By ensuring the consistency of the element scaling factors within each row of the overall mass and stiffness matrices, i.e.:

[0061]

[0062] The dynamic characteristics similarity between the jacket offshore wind turbine prototype and the scaled model can be achieved.

[0063] S24: Based on the sufficient condition for the structural dynamic characteristics similarity to be satisfied during the assembly process in S23, since the matrix of the overall structure is assembled from the matrices of each element in the global coordinate system, to ensure that the scaling factors of each element in the same row of the overall matrix are consistent and equal to the expected value, let the global mass and stiffness matrices of each element participating in the same degree of freedom of the structure maintain the same scaling factor in this row, that is:

[0064]

[0065]

[0066] Where and respectively represent the scaling factors of the global stiffness matrices of any two elements c and c' participating in the global degree of freedom i in the i-th row, and respectively represent the scaling factors of the global mass matrices of the two elements in the i-th row, and respectively represent the scaling factors of the mass and stiffness matrices of the overall structure in the i-th row.

[0067] Since the support structure of the jacket offshore wind turbine is welded by four types of hollow beam elements, and there is a situation where the same nodes are shared among the elements, therefore, when the scaling factors of the elements in the same row of the global mass matrix and stiffness matrix of each type of hollow beam element are consistent, and this scaling factor also remains consistent among the four types of hollow beam elements, this sufficient condition is satisfied.

[0068] S25: Further, based on the sufficient condition for the structural dynamic characteristics similarity to be satisfied during the coordinate transformation process in S23, let the scaling factors of all elements in the dimension-uniformed mass matrix in the local coordinate system be consistent, and the scaling factors of all elements in the stiffness matrix are also consistent.

[0069] Let the rotation angles of the global coordinate system of the jacket offshore wind turbine relative to the local coordinate system of a certain hollow beam element be α, β, γ on the x, y, z axes respectively. Then the displacements x 1 , y 1 and z 1 of node 1 of the hollow beam element in the local coordinate system contribute to the displacement of this point in the x direction in the global coordinate system as , , ; In other words, during the coordinate transformation process, the three displacement degrees of freedom in the local coordinate system all contribute to the same degree of freedom in the global coordinate system. To meet the condition that the scaling coefficients of the same-row elements in the global mass matrix and stiffness matrix of the hollow beam element in S24 are consistent, the mass and stiffness scaling coefficients of the displacement degrees of freedom on the three axes in the local coordinate system are kept consistent. According to the expressions in S22, this process is equivalent to the scaling coefficients on the tension / compression and bending degrees of freedom of the beam element being consistent, that is:

[0070]

[0071]

[0072] The rotational degrees of freedom on the three axes in the local coordinate system also contribute to the same degree of freedom in the global coordinate system. Finally, the sufficient condition for dynamic characteristic similarity during the coordinate transformation process is obtained as:

[0073]

[0074] .

[0075] S26: In the hollow beam element, combining the expressions of the cross-sectional area, moment of inertia, polar moment of inertia, and rotational inertia of the element, the results obtained in S24 and S25 are further deduced and simplified to obtain the general expression for the cross-sectional diameter and thickness of the hollow beam during the scaling process. Subsequently, according to the general expression, the scaling calculation of the hollow beam element is completed. The specific steps are as follows:

[0076] S261: Simultaneously establish the element scaling coefficient expression in S22, the consistency condition between hollow beam elements in S24, and the scaling coefficient expression of the parameters of the cylindrical cross-section beam:

[0077]

[0078] where represents the outer diameter of the hollow cylindrical beam, represents the inner diameter of the hollow cylindrical beam, and the following simplified results are obtained:

[0079]

[0080]

[0081] When the length scaling coefficients of each hollow beam element in the jacket offshore wind turbine are consistent, that is , this result will be further simplified to:

[0082]

[0083] That is, the cross-sectional area scaling factors of the four beam elements that make up the jacket offshore wind turbine structure are kept consistent, among which Scaling factor by diameter , thickness scaling factor and the ratio of thickness to diameter in the prototype express:

[0084] ;

[0085] S262: Combining the scaling factor expression in S22, the sufficient condition obtained in S25, and the hollow beam unit section parameter expression, the following simplified result is obtained:

[0086]

[0087]

[0088] When the jacket offshore wind turbine scale model and prototype are made of the same material, the result will be further simplified to:

[0089]

[0090] Replace the inner diameter in this expression Replace with Thickness Thickness-diameter ratio in the prototype ,get:

[0091]

[0092] Finally, the thickness scaling factor is simplified to The expression is:

[0093] .

[0094] S3: In the scaled model, the length, width and height ratio of the cabin 5 is kept unchanged, and the mass scaling factor of the cabin 5 is made equal to the scaling factor of the hollow beam unit to scale the cabin 5 unit.

[0095] Based on the above discussion results, during the design process of the jacket-type offshore wind turbine scaled model, it is necessary to first ensure that each hollow beam element has a consistent length scaling factor and uses the same material as the prototype. Next, determine the cross-sectional area scaling factor for each hollow beam element according to the simplified formula in S261, and then preliminarily determine the cross-sectional diameter scaling factor of the hollow beam element. The diameter scaling factor value obtained at this stage is usually slightly larger than the length scaling factor value. Then, calculate the thickness scaling factor of the hollow beam element based on the diameter scaling factor according to the simplified formula in S262, and further calculate the thickness of the hollow beam element in the scaled model to complete the scaling calculation of the hollow beam element. Finally, scale the nacelle 5 unit in the model. During this process, the ratio of the length, width, and height of the nacelle 5 should be kept unchanged, and the mass scaling factor of the nacelle 5 should be made equal to the scaling factor of the hollow beam element.

[0096] The jacket-type offshore wind turbine scaled model obtained by the above method will have similar structural dynamic characteristics to the prototype, that is, the normalized modal shapes of each order are consistent, and the natural frequencies of each order are scaled according to the same ratio. The scaling factor is inversely proportional to the length scaling factor, that is:

[0097] 。

[0098] The method and effect of the present invention will be specifically described below through embodiments.

[0099] Embodiment

[0100] According to an offshore wind power project, construct a simplified prototype of a jacket-type offshore wind turbine as shown in Figure 1 . The basic parameters of the four types of beam elements in the prototype are shown in Table 1.

[0101] Table 1 Cross-sectional parameters and materials of the prototype beam elements

[0102]

[0103] Scale this prototype at a length scaling ratio of 1:100. According to the expression in S261, plot the relationship curves of the diameters and cross-sectional area scaling factors of the four types of hollow beam elements. The results are as shown in . Let Figure 3 , and the diameter scaling factors of the four types of beam elements are obtained respectively as: , , , , .

[0104] According to the simplified formula in S262, plot the relationship curves of the diameters and thickness scaling factors of the four types of hollow beam elements. The results are as shown in . Among them, when Figure 4 is 100, is is also 100, which indicates that when the scaling factor of the cross-sectional dimension is the same as that of the beam element length, the dynamic characteristic similarity condition in S25 can be satisfied. However, such scaling makes the wall thickness of the element in the scaled model too small to ensure the manufacturing accuracy through conventional processing means.

[0105] As decreases, the value of will rapidly decline at a greater slope, which indicates that by fine-tuning the value of the thickness scaling factor the scaling requirement for the cross-sectional thickness

[0106] can be significantly relaxed. Based on the calculation results of the diameter scaling factor the thickness scaling factors

[0107] of the four hollow beam elements are calculated according to the simplified formula in S262, and the diameters and thicknesses of each hollow beam element in the scaled model are further calculated. The results are shown in Table 2.

[0108]

[0109] The nacelle in the scaled model is a solid cuboid mass block made of structural steel, which is the same as the prototype. Its mass scaling factor is the same as that of the beam element, that is: On this basis, its external dimension scaling factor is calculated as: .

[0110] The simulation models of the prototype and the scaled model are constructed in the finite element simulation software. The hollow beam elements in the structure are modeled using Beam elements, and the nacelle is modeled using Solid elements. The mesh elements of the prototype and the model are set to 50mm and 0.5mm respectively, and the four main legs are simply supported on the ground.

[0111] The modal analysis is performed on the simulation models of the two, and their first 10 natural frequencies and normalized modal vibration modes are calculated respectively. The scaled frequency of the model is obtained by calculating the product of the frequency of the scaled model and the length scaling factor, and the frequency scaling error between the model and the prototype is calculated through the scaled frequency. The results are shown in Table 3.

[0112] Table 3 Frequency scaling results obtained from modal analysis

[0113]

[0114] The frequency scaling error values of each order of modal in the above table are all below 3%, indicating that the frequency test results in the scaled model can accurately reflect the natural frequency characteristics of the prototype.

[0115] Through the Modal Assurance Criterion (MAC) formula:

[0116]

[0117] Calculate the similarity of the normalized modal vibration modes of the prototype and the scaled model, and the results are shown in Table 4.

[0118] Table 4 MAC values for the first 10 modes

[0119]

[0120] The MAC values of each mode in the above table are all above 0.98, further verifying the similarity of the structural dynamic characteristics between the jacket offshore wind turbine prototype and the scaled model.

[0121] The present invention proposes a design method for a scaled model of a jacket wind turbine, with the focus on ensuring the similarity of the structural dynamic characteristics between the scaled model and the prototype, so that the scaled model and the prototype have proportionally scaled natural frequencies and consistent normalized modal vibration modes, solving the problem of dynamic characteristic mismatch between the model and the prototype caused by traditional scaling methods. The model designed by the method of the present invention can accurately reflect the structural vibration characteristics of the prototype, thus providing a reliable experimental solution for the research on the structural health monitoring of jacket offshore wind turbines.

[0122] Traditional scaling methods for truss structures only calculate the tensile, compressive and bending degrees of freedom of two-dimensional unit structures, and do not consider the dynamic characteristics of the structure sufficiently, restricting the similarity between the scaled model and the prototype. In the similarity calculation process of the present invention, the jacket beam element is regarded as a three-dimensional Euler-Bernoulli beam, considering 12 degrees of freedom including tensile, compressive, bending and torsion at its two nodes. The processing method of the present invention fully considers the common vibration modes of the jacket hollow beam element, thereby improving the performance of the scaled model in reflecting the structural dynamic characteristics of the prototype.

[0123] Since the jacket beam element of the offshore wind turbine is a large-size thin-wall structure, traditional scaling methods based on dimensional analysis will result in too small wall thickness of the model, making it difficult to manufacture by conventional processing means, and the feasibility is greatly reduced. The present invention combines the beam element cross-section parameter expression to deduce the relationship between the beam element cross-section and the diameter scaling coefficient, so that the design process is no longer restricted by the strict requirements for the thickness ratio in traditional methods, thus effectively reducing the processing difficulty and complexity, and improving the application flexibility and wide applicability of this method.

[0124] The above-described embodiments are only a preferred solution of the present invention, but they are not intended to limit the present invention. Those of ordinary skill in the relevant technical field can still make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all technical solutions obtained by means of equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A method for dynamic characteristic similarity scaling of a jacket offshore wind turbine structure, characterized in that, The details are as follows: S1: Simplify and model the prototype structure of the target jacket offshore wind turbine into a scaled-down model of a space truss structure; the space truss structure includes a nacelle (5) unit and four hollow beam units with uniform thickness; there is a situation where the four hollow beam units share the same node, and the scaling coefficients of the same-row elements in the global mass matrix and stiffness matrix of each hollow beam unit are the same, and this scaling coefficient also remains the same among the four hollow beam units; S2: In the scaled-down model, based on the fact that the cross-sectional area scaling coefficients of the four hollow beam units are the same, preliminarily determine the cross-sectional diameter scaling coefficient of the hollow beam unit; then calculate the thickness scaling coefficient of the hollow beam unit based on the cross-sectional diameter scaling coefficient, and further calculate the thickness of the hollow beam unit to complete the scaling calculation of the hollow beam unit; S3: In the scaled-down model, keep the ratio of the length, width and height of the nacelle (5) unchanged, and make the mass scaling coefficient of the nacelle (5) equal to the scaling coefficient of the hollow beam unit to scale the nacelle (5) unit.

2. A dynamic characteristic similarity scaling method for a jacket offshore wind turbine structure according to claim 1, characterized in that In the above S1, the four hollow beam units are respectively the support member (1), the main leg (2), the diagonal brace (3) and the tower barrel (4); several upper parts of the main legs (2) are arranged inclined inward, and the main legs (2) are fixedly connected along the axial direction by several staggered support members (1); the top of all the main legs (2) is fixedly provided with a vertical tower barrel (4) through the diagonal brace (3), and the nacelle (5) is fixedly arranged at the top of the tower barrel (4); In the scaled-down model, the length, cross-sectional diameter and thickness of each hollow beam unit are the same as those of the prototype of the jacket offshore wind turbine; the diagonal brace (3) is obtained by equivalent simplification of mass and stiffness on the basis of the wind turbine transition platform; the nacelle (5) is simplified into a cuboid hollow mass block, and its mass is equal to the sum of the masses of the nacelle (5) and the blades in the original jacket offshore wind turbine.

3. A dynamic characteristic similarity scaling method for a jacket offshore wind turbine structure according to claim 1, characterized in that In the scaled-down model, the four hollow beam units are regarded as undamped three-dimensional Euler-Bernoulli beams, and each hollow beam unit contains a total of 12 degrees of freedom from 2 nodes.

4. A dynamic characteristic similarity scaling method for a jacket offshore wind turbine structure according to claim 1, characterized in that The cross-sectional area scaling factor has the following calculation formula: ; where is the diameter scaling factor, is the thickness scaling factor, is the ratio of the thickness to the diameter in the prototype.

5. A method for dynamic characteristic similarity scaling of a jacket offshore wind turbine structure according to claim 1, characterized in that The thickness scaling factor has the following calculation formula: ; where is the diameter scaling factor, is the length scaling factor, is the ratio of the thickness to the diameter in the prototype.

6. A dynamic characteristic similarity scaling system for a jacket-type offshore wind turbine structure, characterized in that, Including: A scaled-down model construction module, used to simplify and model the prototype structure of the target jacket offshore wind turbine into a scaled-down model of a space truss structure; the space truss structure includes a nacelle (5) unit and four hollow beam units with uniform thickness; there is a situation where the four hollow beam units share the same node, and the scaling coefficients of the same-row elements in the global mass matrix and stiffness matrix of each hollow beam unit are the same, and this scaling coefficient also remains the same among the four hollow beam units; A hollow beam unit scaling calculation module, used to preliminarily determine the cross-sectional diameter scaling coefficient of the hollow beam unit in the scaled-down model based on the fact that the cross-sectional area scaling coefficients of the four hollow beam units are the same; then calculate the thickness scaling coefficient of the hollow beam unit based on the cross-sectional diameter scaling coefficient, and further calculate the thickness of the hollow beam unit to complete the scaling calculation of the hollow beam unit; A nacelle (5) unit scaling module, used to keep the ratio of the length, width and height of the nacelle (5) unchanged in the scaled-down model, and make the mass scaling coefficient of the nacelle (5) equal to the scaling coefficient of the hollow beam unit to scale the nacelle (5) unit.

7. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by a processor, it can implement the dynamic characteristic similarity scaling method for the jacket offshore wind turbine structure as described in any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that, A computer program is stored on the storage medium, and when the computer program is executed by a processor, it implements the dynamic characteristic similarity scaling method for the jacket offshore wind turbine structure as described in any one of claims 1 to 5.

9. A computer electronic device, characterized in that, It includes a memory and a processor; The memory is used for storing a computer program; The processor is used for implementing the dynamic characteristic similarity scaling method for the jacket offshore wind turbine structure as described in any one of claims 1 to 5 when executing the computer program.

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