Jacket offshore wind turbine structure dynamic characteristic similarity scaling method

Abstract

The invention discloses a similar scaling method for dynamic characteristics of a jacket offshore wind turbine structure, and belongs to the field of scaling model design. The method comprises the steps that a target jacket offshore wind turbine prototype structure is simplified and modeled into a scaling model of a space truss structure; according to the fact that the cross section area scaling coefficients of the four hollow beam units are kept consistent, the cross section diameter scaling coefficients of the hollow beam units are preliminarily determined; then calculating a thickness scaling coefficient of the hollow beam unit, further calculating the thickness of the hollow beam unit, and completing scaling calculation of the hollow beam unit; and keeping the length-width-height ratio of the cabin unchanged, and enabling the mass scaling factor of the cabin to be equal to the scaling factor of the hollow beam unit so as to scale the cabin unit. The method is used for designing the jacket offshore wind turbine scaling model, the constructed scaling model can keep structural dynamic characteristics similar to those of a prototype, and the method can be used for meeting research requirements of wind turbine structural performance evaluation in a design stage and a wind turbine structural health monitoring method in an 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 the structure of jacket offshore wind turbines. 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 size 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 the research of 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 are, for example, 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 method for determining the similarity scaling of 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 an airship 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 similar scaling of the jacket offshore wind turbine structure. The method of the present invention can maintain the structural dynamic similarity between the designed scaled model and the prototype, that is, the natural frequencies of each order are scaled in the same proportion, 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 jacket beam element, and can adaptively adjust the thickness scaling coefficient of the structural element according to actual needs, relaxing the requirement for the machining 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 similar scaling of the jacket offshore wind turbine structure, specifically 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 units 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 units, preliminarily determine the scaling coefficient of the cross-sectional diameter of the hollow beam unit; subsequently, calculate the thickness scaling coefficient of the hollow beam unit based on the scaling coefficient of the cross-sectional diameter, and further calculate the thickness of the hollow beam unit to complete the scaling calculation of the hollow beam unit;

[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 unit to scale the nacelle unit.

[0010] Preferably, in S1, the four hollow beam units are respectively a support, a main leg, a diagonal brace, and a tower barrel; several upper parts of the main legs are arranged obliquely inward, and the main legs are fixedly connected axially through several staggered supports; a vertical tower barrel is fixed to the top of all the main legs through diagonal braces, 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 unit are the same as those of the jacket offshore wind turbine prototype; the diagonal brace 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 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.

[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-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-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, with its denominator being 2 times the thickness-diameter ratio k and the numerator being the diameter scaling factor minus the square root of the difference between two terms. The first term is the square of the length scaling factor multiplied by (1 minus the square of 2 times the thickness-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 scaled model construction module for simplifying and modeling 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 units with uniform thickness;

[0019] A hollow beam unit scaling calculation module for initially determining the cross-sectional diameter scaling factor of the hollow beam unit in the scaled model according to the consistency of the cross-sectional area scaling factors of the four hollow beam units; subsequently, calculating the thickness scaling factor of the hollow beam unit based on the cross-sectional diameter scaling factor, and further calculating 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 aspect 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 dynamic 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 a relational expression for the relationship between the section 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 the Euler-Bernoulli beam element;

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

[0031] Figure 4For four kinds of hollow beam elements Relationship curve;

[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 dynamic characteristic similarity scaling method for 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 kinds of 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 to incline inwards, 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 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 kinds of hollow circular cylinder 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 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 by hollowing out the center.

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

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

[0039] S21: Regard the four kinds of hollow beam units as undamped three-dimensional Euler-Bernoulli beams, and each kind of 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 and compressive degrees of freedom in the axial direction, corresponds to the bending degrees of freedom in the xoy plane, corresponds to the bending degrees of freedom in the xoz plane, corresponds to the rotational degrees of freedom about the axis; 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 rotation 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 and 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, shear modulus, cross-sectional area of the hollow beam element, length, moment of inertia of the cross-section, and 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 an element in the tensile and compressive stiffness matrix, , and respectively represent three types of elements with different dimensions in the bending stiffness matrix, represents an 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 an element in the tensile and 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 element in the mass matrix be M and the dimension of the element in the stiffness matrix be MT -2 , then the expression of the element scaling factor for both 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 the global coordinate system through coordinate transformation. The global transformation expression is:

[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 - unit 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 are cases 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 the three axes at 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 satisfy 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 conditions for dynamic characteristic similarity during the coordinate transformation process are obtained as follows:

[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 derived 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 solve 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 hollow beam elements in the jacket offshore wind turbine have a consistent length scaling coefficient, that is , this result will be further simplified to:

[0082]

[0083] That is, the cross-sectional area scaling coefficients 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 cross-sectional parameter expression of the hollow beam unit, 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 offshore wind turbine scaled model, it is necessary to first ensure that each hollow beam element has a consistent length scaling coefficient and uses the same material as the prototype. Next, according to the simplified formula in S261, determine the cross-sectional area scaling coefficient of each hollow beam element, and then preliminarily determine the cross-sectional diameter scaling coefficient of the hollow beam element. The diameter scaling coefficient value obtained at this stage is usually slightly larger than the length scaling coefficient value. Then, calculate the thickness scaling coefficient of the hollow beam element based on the diameter scaling coefficient 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 aspect ratio of the length, width, and height of the nacelle 5 should be kept unchanged, and the mass scaling coefficient of the nacelle 5 should be made equal to the scaling coefficient of the hollow beam element.

[0096] The jacket 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 the same, and the natural frequencies of each order are scaled according to the same ratio. The scaling coefficient is inversely proportional to the length scaling coefficient, 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 the jacket 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 the 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 coefficients of the four types of hollow beam elements, and the results are as shown in . Let Figure 3 , and the diameter scaling coefficients 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 coefficients of the four types of hollow beam elements, and the results are as shown in . Among them, when Figure 4 is 100, when 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 elements in the scaled model too small to ensure the manufacturing accuracy by conventional processing means.

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

[0106] Based on the calculation results of the diameter scaling factor , according to the simplification formula in S262, the thickness scaling factors of the four hollow beam elements are calculated, and the diameters and thickness values of each hollow beam element in the scaled model are further calculated. The results are shown in Table 2.

[0107] Table 2 Cross-sectional parameters of each element in the scaled model

[0108]

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

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

[0111] Modal analysis is carried out on the simulation models of the two, and their first 10 natural frequencies and normalized modal vibration modes are calculated respectively. The scaling 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 scaling 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 mode 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] The similarity of the normalized modal shapes of the prototype and the scaled - down model is calculated, and the results are shown in Table 4.

[0118] Table 4 MAC values on the first 10 modal orders

[0119]

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

[0121] The present invention proposes a design method for the scaled - down model of a jacket - type wind turbine, with the emphasis on ensuring the similarity of the structural dynamic characteristics between the scaled - down model and the prototype, so that the scaled - down model and the prototype have proportionally scaled natural frequencies and consistent normalized modal shapes, solving the problem of the mismatch of dynamic characteristics between the model and the prototype brought about 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 - type 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 sufficiently consider the dynamic characteristics of the structure, restricting the similarity between the scaled - down 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 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 - down 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 - thickness structure, traditional scaling methods based on dimensional analysis will result in too small a wall thickness of the model, making it difficult to manufacture by conventional processing means and greatly reducing the feasibility. The present invention combines the cross - section parameter expression of the beam element to deduce the relationship between the cross - section of the beam element and the scaling coefficient of the diameter, so that the design process is no longer restricted by the strict requirements for the thickness ratio in traditional methods, thus effectively reducing the difficulty and complexity of processing and improving the application flexibility and wide applicability of this method.

[0124] The embodiments described above 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 similar scaling method for the dynamic characteristics 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 model of a space truss structure; the space truss structure includes a nacelle (5) unit and four types of hollow beam units with uniform thickness; S2: In the scaled model, the cross-sectional area scaling coefficients of the four hollow beam units are kept consistent, and the cross-sectional diameter scaling coefficient of the hollow beam unit is preliminarily determined; then the hollow beam unit thickness scaling coefficient is calculated based on the cross-sectional diameter scaling coefficient, and the thickness of the hollow beam unit is further calculated to complete the scaling calculation of the hollow beam unit; 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.

2. A similar scaling method for the dynamic characteristics of a jacket offshore wind turbine structure according to claim 1, characterized in that: In the S1, the four hollow beam units are support members (1), main legs (2), diagonal bracing members (3) and towers (4); the upper parts of the plurality of main legs (2) are arranged inwardly inclined, and the main legs (2) are fixedly connected along the axial direction by a plurality of staggered support members (1); a vertical tower (4) is fixed to the top of all the main legs (2) by diagonal bracing members (3), and a cabin (5) is fixed to the top of the tower (4); In the scaled model, the length, cross-sectional diameter and thickness of each hollow beam unit are consistent with those of the jacket offshore wind turbine prototype; 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 to a rectangular hollow mass block, the mass of which is equal to the sum of the mass of the nacelle (5) and the blades in the original jacket offshore wind turbine.

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

4. The method for similarity scaling of the dynamic characteristics of a jacket offshore wind turbine structure according to claim 1, characterized in that: The cross-sectional area scaling factor is the diameter scaling factor and thickness scaling factor Calculated based on; assuming the diameter scaling factor , thickness scaling factor And the ratio k of thickness to diameter in the prototype is known, then Equivalent to The square of the proportional coefficient is multiplied by the ratio of thickness to diameter k; the denominator of the proportional coefficient is 1 minus 2 multiplied by the thickness-to-diameter ratio k and then squared minus 1, and the denominator is 1 minus 2 multiplied by the thickness-to-diameter ratio k and the thickness reduction coefficient Diameter reduction factor The square of the ratio minus 1.

5. The method for similarity scaling of the dynamic characteristics of a jacket offshore wind turbine structure according to claim 1, characterized in that: The thickness scaling factor is calculated by the similarity condition of structural dynamic characteristics; assuming that the diameter scaling factor , length scaling factor And the ratio k of thickness to diameter in the prototype is known, then Expressed as a fraction, the denominator is 2 times the thickness-to-diameter ratio k, and the numerator is the diameter scaling factor Subtract the two terms under the square root, the first term is the length scaling factor The square of the thickness-to-diameter ratio k multiplied by 1 minus 2 multiplied by the square of the thickness-to-diameter ratio k plus 1. The second term is the diameter scaling factor. The square of .

6. A similar scaling system for the dynamic characteristics of offshore wind turbine structures on jackets, characterized in that: include: A scaled model building module is used to 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 cabin (5) unit and four types of hollow beam units with uniform thickness; The hollow beam unit scaling calculation module is used to preliminarily determine the cross-sectional diameter scaling factor of the hollow beam unit in the scaled model according to the consistency of the cross-sectional area scaling factors of the four hollow beam units; then calculate the hollow beam unit thickness scaling factor 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; The cabin (5) unit scaling module is used to keep the length, width and height ratio of the cabin (5) unchanged in the scaled model, and to make the mass scaling factor of the cabin (5) equal to the scaling factor of the hollow beam unit, so as to scale the cabin (5) unit.

7. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instruction is executed by a processor, the method for similarity scaling of dynamic characteristics of a jacket offshore wind turbine structure as claimed in any one of claims 1 to 5 can be implemented.

8. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, and when the computer program is executed by the processor, the method for similarity scaling of dynamic characteristics of a jacket offshore wind turbine structure according to any one of claims 1 to 5 is implemented.

9. A computer electronic device, characterized in that: including memory and processor; The memory is used to store computer programs; The processor is used to implement the similarity scaling method of the dynamic characteristics of 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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