A Distributed Loading and Load Evaluation Method for Wind Turbine Blades

Abstract

The present invention discloses a method for distributed loading and load evaluation of a wind turbine blade. The method includes: determining the required number of loading points and the loading force of each loading point according to the requirement of the target bending moment; extracting the target strain and target deflection under the target bending moment; arranging a servo motor-driven loading module according to the determined number of loading points and the loading force of each loading point; adjusting the shear force of the blade section according to the target bending moment deviation control algorithm so that the loading bending moment deviation is controlled within a set range; applying a bending moment to the blade by controlling the servo motor-driven loading module and recording the corresponding strain and deflection; during the static load test of the blade, comparing the deviation between the measured strain and the target strain and the deviation between the measured deflection and the target deflection. The present invention can effectively solve the problem of excessive local loading force, enabling the static load test loading method to more realistically simulate the actual operating conditions of the wind turbine blade.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power, and particularly relates to a method for distributed loading and load evaluation of a wind turbine blade. Background Art

[0002] During the static test loading of traditional full-scale blades, in order to make the test bending moment borne by the blade envelope the loads under various operating conditions during the operation of the wind turbine, concentrated force loading is used to simulate the design load of the blade. The maximum single-point loading force needs to reach hundreds of kilonewtons. As shown in the traditional static load test loading Figure 1 During the implementation of the static load test, the transmission path of the loading force is as follows: Rotate through a high-power motor or a hydraulic-driven winch. The winch tightens the steel wire rope. The steel wire rope is connected to the blade fixture through a pulley on the fixed bracket, so that the loading force is applied to the blade. During the process of converting the driving force of the motor into the loading force on the blade, loading equipment must be designed and manufactured, such as: blade shell reinforcement and fixture, loading tooling and ground fixing device. The loading force of hundreds of kilonewtons needs to be satisfied on the load transmission path, and these tooling devices need special design and verification.

[0003] The problems existing in the prior art are to simulate the wind load during the actual operation of the wind turbine blade by using the concentrated force loading method. The concentrated force loading causes a large shear force on the local part of the blade, increasing the risk of local buckling or strength failure of the blade. It is necessary to locally strengthen the blade shell and web, which needs to be considered when making the sample blade, and a large amount of materials are consumed. The tested sample blade is locally strengthened, while the actual mass-produced blade is not strengthened. If the loading position is not selected properly, it often brings risks to the mass-produced blade. At the same bending moment level, the blade buckling calculated by using the concentrated force loading is more stringent than the blade buckling factor calculated by using the distributed force loading. The full-scale blade test conditions need to simulate the blade operating conditions, and using the distributed force loading is closer to the actual operating conditions of the blade. From the perspective of equipment and operation, the maximum single-point loading force needs to reach hundreds of kilonewtons. During the implementation of the static load test, loading equipment, blade shell fixtures, loading tooling and ground fixing devices need to be designed and manufactured. The blade shell fixture will locally strengthen the blade, making the cross-section of the blade not fully verified, resulting in risks in some cross-sections of the blade. The weight of the blade fixture is as high as dozens of tons. According to the data of the static load test, the weight of the loading test fixture even exceeds the weight of the blade itself, causing a great load on the blade in the gravity direction. It is quite difficult to flip the blade with the fixture, and the probability of problems increases. The blade fixture not only has a high cost, a long processing cycle, but also is very inconvenient to install. Summary of the Invention

[0004] To solve or partially solve the problems existing in the related art, the present invention provides a method for distributed loading and load evaluation of a wind turbine blade. During static load testing, the method uses distributed loading on the wind turbine blade, which can more realistically simulate the actual operating conditions of the wind turbine blade.

[0005] The present invention provides a method for distributed loading and load evaluation of a wind turbine blade. During static load testing, the method uses distributed loading on the wind turbine blade; the method includes:

[0006] According to the requirements of the target bending moment, determine the number of loading points required for the blade and the loading force at each loading point;

[0007] Extract the corresponding target strain and target deflection under the target bending moment;

[0008] Arrange the servo motor-driven loading module according to the determined number of loading points and the loading force at each loading point;

[0009] According to the target bending moment deviation control algorithm, for each blade section where the servo motor-driven loading module is arranged, adjust the shear force of the blade section so that the deviation between the loading bending moment and the target bending moment is controlled within the set range;

[0010] Apply a bending moment to the blade by controlling the loading force output by the servo motor-driven loading module, and record the corresponding strain and deflection;

[0011] During the static load testing of the blade, compare the deviation between the measured strain and the target strain and the deviation between the measured deflection and the target deflection of each blade section.

[0012] Optionally, it further includes:

[0013] Install the blade on the test platform, and keep the PS side of the blade facing up, the SS side facing down, and the chord direction of the blade parallel to the ground.

[0014] Optionally, the loading force of a single loading point is controlled within 10 kN, and the deviation of the loading force is controlled within 1%.

[0015] Optionally, the target strain is the target strain at the key position of the section; and / or the target deflection is the target deflection at the key position of the section.

[0016] Optionally, the arranging the servo motor-driven loading module according to the determined number of loading points and the loading force at each loading point specifically includes:

[0017] Project the blade onto the ground;

[0018] Arrange the servo motor-driven loading module along the projection direction of the blade on the ground according to the determined number of loading points and the loading force at each loading point.

[0019] Optionally, a servo motor driven loading module is arranged along the projection direction of the main beam of the blade on the ground, so that the loading force of the servo motor driven loading module is distributed on the axial position of the main beam of the blade.

[0020] Optionally, the bending moment is specifically adjusted by the following formula:

[0021]

[0022] W n = 0

[0023] In the formula, W i is the bending moment of section i, W i-1 is the bending moment of section i - 1, L i is the length of section i from the blade root, L i-1 is the length of section i - 1 from the blade root, n is the number of arrangements of the servo motor driven loading module, corresponding to n blade sections, W n is the bending moment of section n closest to the blade tip, F i-1 is the shear force of section i - 1, F n is the shear force of section n.

[0024] Optionally, by controlling the servo motor driven loading module to apply a bending moment to the blade and recording the corresponding strain and deflection, it specifically includes:

[0025] By controlling the servo motor driven loading module to apply a bending moment to the blade, the bending moment is loaded in multiple stages that increase progressively, and the corresponding strain and deflection are recorded.

[0026] Optionally, the servo motor driven loading module is connected to the ground cement pile through a T - shaped bolt or an expansion bolt; and / or the servo motor driven loading module is arranged on the ground through a counterweight.

[0027] Optionally, the method further includes:

[0028] Arranging a servo motor driven loading module in the chord direction of the blade to achieve chord - direction detection of the blade.

[0029] Optionally, the method further includes:

[0030] Identifying a faulty servo motor driven loading module, and by adjusting the loading force of the servo motor driven loading module adjacent to the faulty one, making the bending moment on the blade section originally loaded by the faulty servo motor driven loading module reach the target value.

[0031] The technical solution provided by the present invention may include the following beneficial effects:

[0032] (1) The use of distributed loading can more realistically simulate the concentrated force on the wind turbine blade. There is no need for local strengthening of the test blade itself. The test sample and the mass-produced blade adopt the same structural type, and the test blade can better represent the mass-produced blade;

[0033] (2) The use of distributed loading does not require local enhancement of the blade. The loading section can also be effectively verified. The loading points can be arranged closer to the tip point to cover the verification area of the critical section at the tip, achieving the purpose of full-scale blade verification;

[0034] (3) The use of distributed force loading can effectively avoid the buckling and strength damage to the blade caused by concentrated force loading. On the premise of reaching the envelope load, the risk of blade overload during the test is reduced;

[0035] (4) During the implementation of blade testing, there is no need to manufacture loading tooling such as blade test fixtures, avoiding adding dozens of tons of loading weight to the blade. It can effectively shorten the preparation cycle before blade testing and reduce the complexity of the test;

[0036] (5) By using the distributed loading technology, the bending moment level on the blade cross-section can be adjusted by dozens of loading points, increasing the degree of freedom of load matching and reducing the deviation between the test bending moment and the target bending moment.

[0037] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present invention. Description of the Drawings

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0039] Figure 1 It is a schematic diagram of static load test loading in the prior art;

[0040] Figure 2 It is a schematic diagram of the structure of the servo motor-driven loading module in the embodiment of the present invention;

[0041] Figure 3 It is a schematic diagram of full-scale blade distributed loading in the embodiment of the present invention;

[0042] Figure 4 It is a flowchart of the distributed loading and load evaluation method for wind turbine blades in the embodiment of the present invention. Detailed Embodiments

[0043] Embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present invention will be more thorough and complete, and will fully convey the scope of the present invention to those skilled in the art.

[0044] The terms used in the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The singular forms "a", "the", and "said" used in the present invention and the appended claims are also intended to include the plural forms unless the context clearly dictates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0045] It should be understood that although the terms "first", "second", "third", etc. may be used in the present invention to describe various information, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present invention, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined.

[0046] An embodiment of the present invention provides a method for distributed loading and load evaluation of a wind turbine blade. This method uses distributed loading, which can effectively solve the problem of excessive local loading force, enabling the static load test loading method to more realistically simulate the actual operating conditions of the wind turbine blade.

[0047] Please refer to Figure 3 , this method realizes the distributed loading of the wind turbine blade through a plurality of servo motors driving the loading module 100. The servo motors driving the loading module 100 can be arranged in the tip region, so that the tip region can be fully verified, achieving the purpose of fully verifying the blade structure.

[0048] Since the loading force of a single loading point is only a few thousand Newtons, straps can be used to apply the loading force of each servo motor driving the loading module 100 to the blade. There is no need to strengthen the blade, nor is it necessary to design a special loading fixture for the blade and set aside separate time to install the blade fixture, shortening the test cycle and simplifying the operation of the loading method; since the tens of tons of fixtures on the blade are omitted, the installation process and evaluation process of the blade are made easier.

[0049] The technical solutions of the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0050] Please refer to Figure 4 , this embodiment provides a method for distributed loading and load evaluation of a wind turbine blade. When performing static load testing, this method uses distributed loading on the wind turbine blade, which can more realistically simulate the actual operating conditions of the wind turbine blade. This method generally includes the following steps:

[0051] S101. Determine the number of loading points required for the blade and the loading force at each loading point according to the requirements of the target bending moment;

[0052] Specifically, control the loading force at each loading point within 10 kN, and control the deviation of the blade loading force within 1%.

[0053] S102. Extract the target strain and target deflection under the target bending moment;

[0054] Extract the target strain and target deflection at the key positions of the blade cross-section under the target bending moment. The target strain and target deflection can be measured one-to-one according to the target bending moment. Among them, the key positions of the cross-section are pre-determined, generally referring to the positions on the blade where the strain is relatively large, prone to buckling, and prone to structural deformation.

[0055] S103. Arrange the servo motor-driven loading module 100 according to the determined number of loading points and the loading force at each loading point;

[0056] Please refer to Figure 3 , arrange dozens of servo motor-driven loading modules 100 along the axial direction of the blade in sequence.

[0057] It should be noted that the axial direction of the blade refers to the direction from the blade root to the blade tip, and the chord direction of the blade refers to the direction from the leading edge to the trailing edge.

[0058] Please refer to Figure 2 , each of the servo motor-driven loading modules 100 includes a servo motor 102, a speed reducer 103, and a winch 101. The speed reducer 103 is used to control the deceleration of the servo motor 102. The servo motor 102 is used to drive the winch 101 to rotate. The winch is connected to a steel wire rope. By tightening the steel wire rope, the loading force is applied to the blade. Among them, the steel wire rope is connected to the blade through a strap.

[0059] In this embodiment, the servo motor-driven loading module 100 may further include a movable pulley block, and the movable pulley block is arranged on the steel wire rope; the loading force of a single servo motor-driven loading module 100 can be changed through the movable pulley block.

[0060] Step S103 specifically includes: project the blade onto the ground; arrange the servo motor-driven loading module 10 according to the determined number of loading points and the loading force at each loading point along the axial direction of the projection of the blade on the ground.

[0061] It should be noted that the arrangement of the servo motor drive loading module 100 in this embodiment is not specifically limited, and only the Figure 3 shown arrangement is used for exemplary illustration; specifically, in this embodiment, the servo motor drive loading module 100 is arranged along the axial direction of the blade on the ground. In other embodiments, the servo motor drive loading module 100 can also be arranged above the blade through a corresponding hoisting structure, as long as it can apply a loading force to the blade.

[0062] S104. According to the target bending moment deviation control algorithm, for each blade section where the servo motor drive loading module 100 is arranged, adjust the shear force of the blade section so that the deviation between the loading bending moment and the target bending moment is controlled within a set range;

[0063] When the section bending moment deviation is too high, adjust the shear force of the blade section through the target bending moment deviation control algorithm so that the loading bending moment deviation is controlled within 1%;

[0064] In this embodiment, the blade section refers to any section of the blade that is perpendicular to the blade axis, that is, the blade chord plane.

[0065] S105. Apply a bending moment to the blade by controlling the loading force output by the servo motor drive loading module 100, and record the strain and deflection corresponding to this bending moment;

[0066] By controlling the loading force output by the servo motor drive loading module 100, different bending moments are applied to the blade. In this embodiment, the target bending moment is loaded in five stages in sequence, namely 20%, 40%, 60%, 80% and 100% of the target bending moment, and the strain and deflection corresponding to each different bending moment are recorded.

[0067] S106. During the static load test of the blade, compare the deviation between the measured strain and the target strain and the deviation between the measured deflection and the target deflection of each blade section.

[0068] In this embodiment, it also includes:

[0069] Install the blade on the test platform, and keep the PS side (leeward side) of the blade facing up and the SS side (windward side) facing down, and the blade chord direction is parallel to the ground.

[0070] In this embodiment, a plurality of servo motor drive loading modules 100 are arranged along the axial direction of the main beam of the blade on the ground, so that the loading forces of the servo motor drive loading modules 100 are distributed at the axial positions of the blade main beam.

[0071] In this embodiment, the bending moment applied by the servo motor drive loading module 100 to the blade is specifically adjusted by the following formula:

[0072]

[0073] W n = 0

[0074] In the formula, W i is the bending moment of section i, and W i-1 is the bending moment of section i - 1, L i is the length of section i from the blade root, and L i-1 is the length of section i - 1 from the blade root. n is the number of arrangements of the servo - motor - driven loading module 100, corresponding to n blade sections. W n is the bending moment of section n, the section closest to the blade tip, and F i-1 is the shear force of section i - 1, and F n is the shear force of section n.

[0075] In this embodiment, by controlling the loading force output by the servo - motor - driven loading module 100, a bending moment is applied to the blade, and the corresponding strain and deflection are recorded. Specifically, it includes:

[0076] In this embodiment, the servo - motor - driven loading module 100 is connected to the ground cement pile through T - shaped bolts or expansion bolts; and / or the servo - motor - driven loading module 100 is arranged on the ground through counterweights.

[0077] In this embodiment, the method further includes:

[0078] A plurality of servo - motor - driven loading modules 100 are arranged along the chord direction of the blade to realize the detection in the chord direction of the blade. According to the requirements of the test scheme, loading modules are arranged in the chord - length direction of the blade to verify the bending moment on the blade section. This embodiment can simultaneously perform detection and verification in the axial and chord directions of the blade. Compared with only detecting and verifying in the axial direction of the blade, its evaluation result of the blade is more accurate.

[0079] In this embodiment, the method further includes:

[0080] Identifying the faulty servo - motor - driven loading module 100, and by adjusting the loading force of the servo - motor - driven loading module 100 adjacent to the faulty servo - motor - driven loading module 100, the bending moment on the blade section originally loaded by the faulty servo - motor - driven loading module 100 is made to reach the target value.

[0081] As described above, it is only the embodiment of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and scope of the present invention are all included in the protection scope of the present invention.

Claims

1. A distributed loading and load evaluation method for a fan blade, characterized in that During the static load test, this method uses distributed loading on the wind turbine blade. This method includes: According to the requirements of the target bending moment, determine the number of loading points required for the blade and the loading force at each loading point. The loading force of a single loading point is controlled within 10 kN, and the deviation of the loading force is controlled within 1%. Extract the corresponding target strain and target deflection under the target bending moment. Arrange the servo motor-driven loading module according to the determined number of loading points and the loading force at each loading point. The servo motor-driven loading module is used to apply the loading force to the blade. According to the target bending moment deviation control algorithm, for the n blade sections with n servo motor-driven loading modules arranged, adjust the shear force magnitude of the blade section to control the deviation between the loading bending moment and the target bending moment within the set range. The loading bending moment of section i is obtained based on the cumulative sum of the shear forces of each section from section i - 1 to section n, the spacing between section i and section i - 1, and the loading bending moment of section i - 1. Section n is the section closest to the blade tip and the loading bending moment is 0. Apply a bending moment to the blade by controlling the loading force output by the servo motor-driven loading module, and record the corresponding strain and deflection. During the static load test of the blade, compare the deviation between the measured strain and the target strain and the deviation between the measured deflection and the target deflection of each blade section.

2. The distributed loading and load evaluation method for a fan blade according to claim 1, characterized in that It also includes: Install the blade on the test platform, and keep the PS side of the blade facing up and the SS side facing down, with the blade chord parallel to the ground.

3. The distributed loading and load evaluation method for a fan blade according to claim 1, characterized in that The target strain is the target strain at the key position of the section; and / or the target deflection is the target deflection at the key position of the section.

4. The distributed loading and load evaluation method for a fan blade according to claim 1, characterized in that, The arranging the servo motor-driven loading module according to the determined number of loading points and the loading force at each loading point specifically includes: Project the blade onto the ground. Arrange the servo motor-driven loading module along the projection direction of the blade on the ground according to the determined number of loading points and the loading force at each loading point.

5. The distributed loading and load evaluation method for a fan blade according to claim 4, wherein Arrange the servo motor-driven loading module along the projection direction of the main beam of the blade on the ground, so that the loading force of the servo motor-driven loading module is distributed in the axial position of the blade main beam.

6. The distributed loading and load evaluation method for a fan blade according to claim 1, characterized in that, The bending moment is specifically adjusted by the following formula: W n ＝0 Where, W i is the bending moment of section i, W i-1 is the bending moment of section i - 1, L i is the length of section i from the blade root, L i-1 is the length of section i - 1 from the blade root, n is the number of servo motor driven loading modules arranged, corresponding to n blade sections, W n is the bending moment of section n closest to the blade tip, F i-1 is the shear force of section i - 1, F n is the shear force of section n.

7. The distributed loading and load evaluation method for a fan blade according to claim 1, characterized in that, The applying a bending moment to the blade by controlling the servo motor-driven loading module and recording the corresponding strain and deflection specifically includes: Apply a bending moment to the blade by controlling the servo motor-driven loading module. The bending moment is loaded in multiple stages in sequence, and the corresponding strain and deflection are recorded.

8. The distributed loading and load evaluation method for a fan blade according to claim 1, characterized in that The servo motor-driven loading module is connected to the ground cement pile through a T-bolt or expansion bolt; and / or the servo motor-driven loading module is arranged on the ground through a counterweight.

9. The method for distributed loading and load evaluation of a wind turbine blade as claimed in claim 1, wherein this method further includes: Arrange the servo motor-driven loading module in the chord direction of the blade to achieve the detection in the chord direction of the blade.

10. The method for distributed loading and load evaluation of a wind turbine blade as claimed in claim 1, wherein this method further includes: Identify the faulty servo motor drive loading module, and by adjusting the loading force of the servo motor drive loading module adjacent to the faulty servo motor drive loading module, make the bending moment on the blade cross-section originally loading the faulty servo motor drive loading module reach the target value.

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