Wind power blade static test simulation method

Abstract

The invention discloses a wind power blade static test simulation method, which comprises the following steps: S1, determining the loading point positions and the loading point number of a wind power blade, determining the position of a fixed pulley model, and applying a test acting force to the loading point positions corresponding to the wind power blade through the fixed pulley model; s2, wind power blade deformation is obtained through finite element calculation, the positions of all loading points after deformation and the moment arms of all preset sections in the verification area are calculated, and the positions of all the loading points and the equivalent loads of all the preset sections are calculated; s3, judging whether the equivalent load can envelop the target load or not, if not, adjusting the test acting force, and repeating the steps S2-S3; and if yes, outputting the current wind power blade deformation parameter and the current test scheme information. According to the invention, loading of the blade is simulated through the fixed pulley model, a loading condition which is completely consistent with a test is realized, and a more accurate analysis result is obtained; meanwhile, through continuous iteration, the test is fully verified, the target load is matched more accurately, and the design safety risk is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power, and in particular to a static test simulation method for a wind power blade. Background Art

[0002] In order to pursue power generation efficiency, the length of wind turbine blades is increasing. At the same time, in order to reduce costs, the thickness of blade plies is reduced, resulting in a decrease in flapping stiffness. These two factors make the deformation of blades under extreme loads larger and larger, and the geometric nonlinear deformation characteristics become more and more obvious. However, most existing simulation methods treat the loading process of blades as a linear problem analysis and do not consider the actual loading method. Figure 1 This is a schematic diagram of the load application method of the existing simulation method. It can be seen that the load direction remains unchanged during the loading process. When linear analysis is used, its z-direction displacement is obviously unreliable, resulting in a large deviation between the actual test load and the target load of the long flexible blade under large deformation, which in turn makes the degree of consistency between the simulation and test deformation and strain data poor, especially in the blade tip part with smaller stiffness, the deviation will be greater, resulting in insufficient test verification and posing risks to the safety of the blade structure.

[0003] At the same time, in the iterative process of determining the test loading position and loading force through numerical calculation, the existing technical solutions only focus on efficiency but do not pay attention to its accuracy, resulting in poor consistency of simulation tests.

[0004] Therefore, how to provide a static test simulation method for wind turbine blades that can take into account the dynamic loading process of the actual test, so as to more accurately match the target load, fully verify the test, reduce the design safety risk, improve the consistency of simulation, and greatly improve the prediction accuracy of various data such as displacement and strain compared with existing methods is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0005] The purpose of the present invention is to provide a wind turbine blade static test simulation method, which can take into account the actual test of the follow-up loading process, so as to more accurately match the target load, fully verify the test, reduce the design safety risk, improve the consistency of simulation test, and greatly improve the prediction accuracy of various data compared with the existing methods.

[0006] In order to solve the above technical problems, the present invention provides a wind turbine blade static test simulation method, comprising the following steps:

[0007] Step S1: determining the position and number of loading points on the wind turbine blade, determining the position of the fixed pulley model, and applying a test force to the corresponding loading point position on the wind turbine blade through the fixed pulley model;

[0008] Step S2: obtaining the deformation of the wind turbine blade by finite element calculation, calculating the force arm of each loading point position and each preset cross section in the verification area after deformation, and calculating the equivalent load of each loading point position and each preset cross section;

[0009] Step S3: determine whether each of the equivalent loads can envelop the corresponding target load; if not, adjust the test force and repeat steps S2-S3; if yes, output the deformation parameters of the current wind turbine blade and the current test scheme information.

[0010] The static test simulation method for wind turbine blades of the present invention changes the load application method in the prior art and simulates the loading process of the wind turbine blades through a fixed pulley model to ensure consistency with the actual test loading method; at the same time, the accuracy of the test scheme information is fully verified through a continuous iteration process to ensure that the actual load corresponding to the final iteration result reaches the target load, minimize the deviation between simulation and test, improve the consistency of simulation and test, and thus reduce the design safety risk.

[0011] Optionally, the equivalent load at each loading point position is the product of the force arm at each loading point position and the test force at each loading point position.

[0012] Optionally, the verification area takes the blade root of the wind turbine blade as a starting point, and the length of the verification area is not less than 70% of the length of the wind turbine blade.

[0013] Optionally, with the preset cross section as the boundary, the equivalent load of each preset cross section is the sum of the bending moments generated by each test force on the tip side of the wind turbine blade at the preset cross section.

[0014] Optionally, judging whether each of the equivalent loads can envelop the corresponding target load specifically comprises the following steps:

[0015] Divide the equivalent load of each loading point position and each preset cross section by the corresponding design load to obtain a corresponding calculated overload coefficient, and determine whether the calculated overload coefficient is within a preset range. If so, each equivalent load can envelop the corresponding target load;

[0016] The preset range is the design overload factor×(1~1.01).

[0017] Optionally, the deformation parameters of the wind turbine blade include displacement and strain of the wind turbine blade.

[0018] Optionally, the current test scheme information includes the loading point position, the number of loading points, the position of the fixed pulley model and the test force at each loading point position.

[0019] Optionally, the step S1 further comprises establishing a finite element model of the wind turbine blade, and the finite element model of the wind turbine blade adopts a shell unit model or a beam unit model.

[0020] Optionally, the step S3 further includes: outputting a simulation value of a strength parameter of the current wind turbine blade;

[0021] The wind turbine blade static test simulation method further includes:

[0022] Step S4: comparing the simulation value of the strength parameter with the allowable value of the strength parameter. If the simulation value of the strength parameter is not greater than the allowable value of the strength parameter, the strength of the wind turbine blade meets the requirement.

[0023] The strength parameters include stress and / or strain.

[0024] Optionally, the step S3 further includes: outputting a characteristic value obtained by the linear buckling simulation analysis of the current wind turbine blade; and the wind turbine blade static test simulation method further includes:

[0025] Step S4: comparing the characteristic value with the standard value of the buckling safety factor. If the characteristic value is greater than the standard value of the buckling safety factor, the stability of the wind turbine blade meets the requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of load application method of existing simulation method;

[0027] Figure 2 This is a flow chart of the wind turbine blade static test simulation method of the present invention;

[0028] Figure 3 An initial state diagram of a simulation model established by the wind turbine blade static test simulation method of the present invention;

[0029] Figure 4 A state diagram of a simulation model established by the static test simulation method for a wind turbine blade of the present invention after deformation;

[0030] Figure 5 This is the state diagram of the wind turbine blade before and after deformation;

[0031] in, Figure 3-Figure 5 The reference numerals in the figures are described as follows:

[0032] 1- Wind turbine blade; 2- Fixed pulley model. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0034] The “plurality” mentioned herein generally means more than two; and when “plurality” is used to indicate the number of certain components, it does not indicate the relationship between the quantities of these components.

[0035] Please refer to Figure 2-Figure 4 , Figure 2 This is a flow chart of the wind turbine blade static test simulation method of the present invention; Figure 3 An initial state diagram of a simulation model established by the wind turbine blade static test simulation method of the present invention; Figure 4 This is a state diagram of the simulation model established by the wind turbine blade static test simulation method of the present invention after deformation.

[0036] The present invention provides a wind turbine blade static test simulation method, comprising the following steps:

[0037] Step S1: determining the position and number of loading points on the wind turbine blade 1, determining the position of the fixed pulley model 2, and applying a test force to the corresponding loading point position on the wind turbine blade 1 through the fixed pulley model 2;

[0038] Step S2: obtaining the deformation of the wind turbine blade 1 by finite element calculation, calculating the position of each loading point after deformation and the force arm of each preset cross section in the verification area, and calculating the equivalent load of each loading point position and each preset cross section;

[0039] Step S3: determine whether each equivalent load can envelop the corresponding target load. If not, adjust the test force and repeat steps S2-S3; if yes, output the deformation parameters of the current wind turbine blade 1 and the current test scheme information.

[0040] The wind turbine blade static test simulation method of the present invention changes the load application method in the prior art, and simulates the loading process of the wind turbine blade 1 through the fixed pulley model 2 to be consistent with the actual test loading method; at the same time, the accuracy of the test scheme information is fully verified through a continuous iteration process to ensure that the actual load corresponding to the final iteration result reaches the target load, minimize the deviation between simulation and test, improve the consistency of simulation and test, and thus reduce the design safety risk.

[0041] Table 1 shows the comparison of the simulated deformation results of the prior art solution and the present invention, and Table 2 shows the comparison of the simulated strain results of the prior art solution and the present invention. It can be seen from Table 1 that the calculated deformation and the tested deformation in the blade tip area of ​​the prior art solution have a large deviation, and the fixed pulley model simulation method proposed in the present invention can eliminate this deviation. Similarly, it can be seen from Table 2 that the calculated strain and the tested strain of the main beam outer skin after 50m of the prior art solution have a large deviation, and the method proposed in the present invention can greatly improve this problem.

[0042] Table 1 Comparison of deformation results

[0043]

[0044] Table 2 Comparison of strain results

[0045]

[0046]

[0047] In step S1 , the positions and number of loading points on the wind turbine blade 1 are usually determined by technicians through experience based on parameters such as target load and size of the wind turbine blade 1 .

[0048] Among them, in step S1, determining the position of the fixed pulley model 2 includes determining the position of the fixed pulley model 2 in the X direction, the Y direction and the Z direction. Since the position of the loading point is equivalent to the position of the fixture in the actual test, the position of the fixed pulley model 2 is equivalent to the position of the winch in the actual test. Therefore, the position of the fixed pulley model 2 needs to consider factors such as actual test conditions.

[0049] Specifically, the X direction, Y direction and Z direction are as follows Figure 5 As shown, the X direction is the direction perpendicular to the axial direction of the wind turbine blade 1 in the horizontal plane; the Y direction is the direction perpendicular to the wind turbine blade 1 in the vertical plane; the Z direction is the extension direction of the wind turbine blade 1 in the horizontal plane; the position of the fixed pulley model 2 in the Z direction is determined based on the loading point position, the fixed pulley model 2 is offset to the side close to the blade root of the wind turbine blade 1 relative to the corresponding loading point position, and the connection line between the fixed pulley model 2 and the loading point position has a preset angle with the X direction, so as to ensure that in the actual test, after the wind turbine blade 1 is deformed, the fixture can still be stably in the initial position and will not fall off the wind turbine blade 1; the position of the fixed pulley model 2 in the X direction is determined based on the scale of the blade test bench, that is, the equipment used to fix the blade root of the wind turbine blade 1 in the actual test; the position of the fixed pulley model 2 in the Y direction must ensure that after the wind turbine blade 1 is deformed, the fixture position and the position of the fixed pulley model 2 are in the same horizontal plane.

[0050] Among them, in step S1, the initial value of the test force is determined by the static test simulation method of the wind turbine blade in the prior art, that is, the loading force that meets the target load determined by the static test simulation method in the prior art is the initial value of the test force applied in the simulation method of the present invention. It can be understood that since the simulation method of the existing technology cannot obtain the accurate deformation after loading, the equivalent load obtained by the loading force determined by it does not match the actual target load. On this basis, the present invention performs iterative analysis and finally obtains the equivalent load that can envelop the target load, which can shorten the analysis time and improve the simulation efficiency.

[0051] It can be seen from the above that the method for determining the initial value of the test force is an existing technology well known to those skilled in the art and will not be described in detail here.

[0052] Among them, in step S2, the equivalent load at each loading point position is the product of the force arm at each loading point position and the test force at each loading point position. To calculate the force arm at each loading point position after deformation, specifically, the coordinates at the blade root after deformation and the coordinates at each loading point position can be obtained, and the force arm at each loading point position after deformation can be calculated by a corresponding post-processing program. The calculation process is well known to those skilled in the art and will not be repeated here.

[0053] At the same time, when verifying whether the equivalent load reaches the target load, it is not only necessary to verify the loading point position, because the equivalent load at the loading point position does not mean that all verification areas have reached it. It is also necessary to select more sections in the verification area and verify the equivalent load at each section. In practice, a preset section is usually selected every two meters in the verification area for verification to ensure that the equivalent load of all verification areas reaches the target load.

[0054] The verification area starts from the root of the wind turbine blade 1 , and its length should be no less than 70% of the length of the wind turbine blade 1 .

[0055] The equivalent load of each preset cross section is calculated as follows: with the preset cross section as the boundary, the equivalent load of each preset cross section is the sum of the bending moments generated by each test force on the blade tip side close to the wind turbine blade 1 at the preset cross section.

[0056] The bending moment generated by the test force on the blade tip side close to the wind turbine blade 1 at the preset cross section is the product of the test force and the vertical distance from the test force to the preset cross section.

[0057] Further, in step S3, it is determined whether each equivalent load can envelop the corresponding target load, which specifically includes the following steps:

[0058] Divide the equivalent load of each loading point and each preset cross section by the corresponding design load to obtain the corresponding calculated overload coefficient, and determine whether the calculated overload coefficient is within the preset range. If so, each equivalent load can envelop the corresponding target load;

[0059] The preset range is the design overload factor×(1~1.01).

[0060] In practice, the equivalent load should not only envelop the target load (with a lower limit), but also should not exceed the target load too much (there are also requirements for the upper limit). For example, if the preset overload factor is 1.1, the calculated overload factors of each loading point and each preset section must be greater than 1.1 and not exceed 1% (1.1*1.01).

[0061] Among them, the design overload coefficient can be selected as needed. For example, 1.1 is generally selected for the front static test, 1.0 can be selected for the rear static test, and for the research overload test to explore the bearing limit of the wind turbine blade, any value greater than 1.10 can be selected, such as 1.3, 1.4, etc.

[0062] Further, in step S3, when the equivalent load can envelope the corresponding target load, the current test scheme is the final test scheme and can be used for actual testing. The current test scheme information usually includes the loading point position, the number of loading points, the position of the fixed pulley model 2 and the test force at each loading point position. In the actual test, the loading point position is the installation position of the fixture on the wind turbine blade 1, and the position of the fixed pulley model 2 is the position of the winch. After determining the above information, the actual test can be carried out to obtain the deformation parameters of the wind turbine blade 1 in the actual test. By comparing the deformation parameters of the wind turbine blade 1 in the actual test with the output deformation parameters of the wind turbine blade 1, it can be determined whether the simulation results are reliable.

[0063] It can be understood that in the actual simulation operation process, step S1 also includes establishing a finite element model of the wind turbine blade 1. The finite element model of the wind turbine blade 1 can be simulated using a shell unit model or a beam unit model. Of course, using a beam unit model for simulation can effectively speed up the iteration efficiency and is a more preferred technical solution.

[0064] In addition, since the simulation method for static testing of wind turbine blades based on the fixed pulley model of the present invention has better simulation consistency and the prediction accuracy of various data such as displacement and strain is greatly improved, its calculation results can also be applied to static test verification, such as strength verification and stability verification, by applying the corresponding working conditions.

[0065] When applied to strength verification, step S3 also includes: outputting a simulation value of a strength parameter of the current wind turbine blade 1;

[0066] The wind turbine blade static test simulation method further includes:

[0067] Step S4: comparing the simulation value of the strength parameter with the allowable value of the strength parameter. If the simulation value of the strength parameter is not greater than the allowable value of the strength parameter, the strength of the wind turbine blade 1 meets the requirement.

[0068] Strength parameters include stress and / or strain.

[0069] In this way, the stress and / or strain of the wind turbine blade 1 can be extracted in the simulation software. The extracted stress is the simulation value of the stress, and the extracted strain is the simulation value of the strain. By comparing the simulation value of the stress with the allowable stress, and comparing the simulation value of the strain with the allowable strain, it is possible to determine whether the strength of the wind turbine blade 1 meets the requirements and complete the strength verification.

[0070] It can be understood that, under the premise that the structure of the wind turbine blade 1 is determined, its allowable stress and allowable strain are also determined values.

[0071] When applied to stability verification, step S3 also includes: outputting the characteristic value obtained by the linear buckling simulation analysis of the current wind turbine blade 1; the wind turbine blade static test simulation method also includes:

[0072] Step S4: comparing the characteristic value obtained by the simulation analysis with the standard value of the buckling safety factor. If the characteristic value obtained by the simulation analysis is greater than the standard value of the buckling safety factor, the stability of the wind turbine blade 1 meets the requirements.

[0073] In this way, the buckling characteristic value of the wind turbine blade 1 can be extracted in the simulation software, and compared with the standard value of the buckling safety factor given in the specification, it can be determined whether the stability of the wind turbine blade 1 meets the requirements, thereby completing the stability check.

[0074] In actual operation, simulation analysis can be performed through simulation software such as Abaqus.

[0075] The above is a detailed introduction to a wind turbine blade static test simulation method provided by the present invention. This article uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core ideas of the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A wind turbine blade static test simulation method, characterized in that: The steps include: Step S1: determining the position and number of loading points on the wind turbine blade, determining the position of the fixed pulley model, and applying a test force to the corresponding loading point position on the wind turbine blade through the fixed pulley model; Step S2: obtaining the deformation of the wind turbine blade by finite element calculation, calculating the force arm of each loading point position and each preset cross section in the verification area after deformation, and calculating the equivalent load of each loading point position and each preset cross section; Step S3: determine whether each of the equivalent loads can envelop the corresponding target load; if not, adjust the test force and repeat steps S2-S3; if yes, output the deformation parameters of the current wind turbine blade and the current test scheme information.

2. The wind turbine blade static test simulation method according to claim 1, characterized in that: The equivalent load at each loading point position is the product of the force arm at each loading point position and the test force at each loading point position.

3. The wind turbine blade static test simulation method according to claim 1, characterized in that: The verification area takes the blade root of the wind turbine blade as a starting point, and the length of the verification area is not less than 70% of the length of the wind turbine blade.

4. The wind turbine blade static test simulation method according to claim 1, characterized in that: With the preset cross section as the boundary, the equivalent load of each preset cross section is the sum of the bending moments generated at the preset cross section by each test force on the blade tip side close to the wind turbine blade.

5. The wind turbine blade static test simulation method according to claim 1, characterized in that: Determining whether each of the equivalent loads can envelop the corresponding target load specifically includes the following steps: Divide the equivalent load of each loading point position and each preset cross section by the corresponding design load to obtain a corresponding calculated overload coefficient, and determine whether the calculated overload coefficient is within a preset range. If so, each equivalent load can envelop the corresponding target load; The preset range is the design overload factor×(1~1.01).

6. The wind turbine blade static test simulation method according to claim 1, characterized in that: The deformation parameters of the wind turbine blade include the displacement and strain of the wind turbine blade.

7. The wind turbine blade static test simulation method according to claim 1, characterized in that: The current test scheme information includes the loading point position, the number of loading points, the position of the fixed pulley model and the test force at each loading point position.

8. The wind turbine blade static test simulation method according to claim 1, characterized in that: The step S1 also includes establishing a finite element model of the wind turbine blade, wherein the finite element model of the wind turbine blade adopts a shell unit model or a beam unit model.

9. The wind turbine blade static test simulation method according to claim 1, characterized in that: The step S3 also includes: outputting a simulation value of a strength parameter of the current wind turbine blade; The wind turbine blade static test simulation method further includes: Step S4: comparing the simulation value of the strength parameter with the allowable value of the strength parameter. If the simulation value of the strength parameter is not greater than the allowable value of the strength parameter, the strength of the wind turbine blade meets the requirement. The strength parameters include stress and / or strain.

10. The wind turbine blade static test simulation method according to claim 1, characterized in that: The step S3 also includes: outputting the characteristic value obtained by the linear buckling simulation analysis of the current wind turbine blade; the wind turbine blade static test simulation method also includes: Step S4: comparing the characteristic value with the standard value of the buckling safety factor. If the characteristic value is greater than the standard value of the buckling safety factor, the stability of the wind turbine blade meets the requirements.

Images