A method for suppressing tower vibration

Abstract

The present invention relates to the technical field of wind turbines, and proposes a method for suppressing tower vibration based on a pitch change strategy, comprising the following steps: pitching the blades of the wind turbine so that the direction of the flapping vibration generated by the blades is not perpendicular to the direction of the tower vibration of the wind turbine; and configuring the frequency of the flapping vibration of the blades to be close to the frequency of the tower vibration.

Description

Technical Field

[0001] The present invention generally relates to the technical field of wind turbines. In particular, the present invention relates to a method for suppressing tower vibration. Background Art

[0002] In recent years, with the improvement of environmental protection awareness and the policy support of various countries, the field of clean energy has shown a rapid development trend. As a new type of energy, clean energy has the advantages of wide distribution, renewable, and less environmental pollution compared with traditional fossil fuels. As a representative of clean energy, the application of wind turbines is growing day by day.

[0003] Wind turbines (or "wind turbines" for short) will generate vortex-induced loads on the tower surface under strong winds, inducing vortex-induced vibration (VIV) of the tower. If the amplitude of the tower vibration is too large, it may affect the safety of the wind turbine. Therefore, tower vibration reduction of wind turbines is a very important part of wind turbine design. Traditionally, additional dampers are usually used, such as water tanks or mechanical dampers to reduce tower vibration, which has the problem of high cost. In addition, the structure of the additional damper is usually more complicated, which will increase the maintenance cost of the wind turbine. In addition, the additional damper also has the potential risk of failure, such as water tank leakage and other problems that affect the normal operation of the wind turbine. Summary of the invention

[0004] In order to solve the above problems in the prior art, the present invention proposes a method for suppressing tower vibration, the method comprising:

[0005] Pitching the blades of the wind turbine generator so that the direction of flapping vibration generated by the blades is not perpendicular to the direction of tower vibration of the wind turbine generator; and

[0006] The frequency of the flapping vibration of the blade is configured to be close to the frequency of the vibration of the tower. In the present invention, the term "close" means that the absolute value of the difference between A and B is less than 30%, especially 20%, more preferably 10%, and most preferably 5% of the absolute value of the smaller absolute value of A and B. The term "non-perpendicular" means that the angle between the two is different from 90°, and the angle is especially 0° to 89°, preferably 0° to 60°, particularly preferably 0° to 45°, and most preferably 0° to 30°.

[0007] In one embodiment of the present invention, it is provided that the vibration includes first-order vibration and second-order vibration.

[0008] In one embodiment of the present invention, it is provided that a modal analysis is performed on the blade and the tower to determine the frequency of the flapping vibration of the blade and the frequency of the vibration of the tower.

[0009] In one embodiment of the present invention, it is provided that the blade angle of the wind turbine is configured so that the blade generates a flapping vibration response in the direction of the tower vibration.

[0010] In one embodiment of the present invention, it is provided that when the amplitude of the flapping vibration of the blade in the vibration direction of the tower is less than a first value, the pitch angle of the blade is increased or the number of the blades to be pitched is increased; and

[0011] When the amplitude of the flapping vibration of the blade in the tower vibration direction is greater than a second value, the pitch angle of the blade is reduced or the number of the blades with pitch changes is increased.

[0012] In one embodiment of the present invention, it is provided that the aerodynamic torque and damping in the torsional direction of the wind rotor of the wind turbine are checked to ensure that the rotation speed of the wind rotor is controllable, for example, within a predetermined range, such as a safe rotation speed range.

[0013] In one embodiment of the present invention, it is provided that the limit load of the wind turbine is checked.

[0014] The present invention also provides a wind turbine generator, comprising:

[0015] a pitch device configured to pitch the blades; and

[0016] A controller configured to perform the following actions:

[0017] Sending a first pitch changing signal to the pitch changing device to change the pitch of the blades so that the direction of the flapping vibration generated by the blades is not perpendicular to the direction of the tower vibration of the wind turbine;

[0018] as well as

[0019] A second pitch changing signal is sent to the pitch changing device to change the pitch of the blades, so that the vibration of the tower can be suppressed by generating aerodynamic damping through the flapping vibration.

[0020] The present invention has at least the following beneficial effects: the present invention designs a pitch strategy based on the vibration coupling characteristics of the tower and blades of a wind turbine, and makes full use of the aerodynamic damping of the blades themselves to suppress the vibration of the tower. Compared with the traditional technical solution of installing additional dampers, the cost of the wind turbine is significantly reduced; the parameter design process of the pitch strategy of the present invention is simple, and based on the target wind turbine model, the optimal pitch strategy parameters can be identified quickly; after the pitch strategy parameters of the present invention are designed, they can be embedded in the wind turbine control logic, and the pitch strategy can be automatically triggered in the target scenario to avoid excessive tower vibration; the pitch strategy deployment and upgrade process adopted by the present invention is simple, and compared with the traditional technical solution of installing additional dampers, there is no operation and maintenance requirement, and it will not interfere with other components of the wind turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] To further illustrate the advantages and features of various embodiments of the present invention, a more detailed description of various embodiments of the present invention will be presented with reference to the accompanying drawings. It will be understood that these drawings only depict typical embodiments of the present invention and are therefore not to be considered as limiting the scope thereof. In the accompanying drawings, for clarity, identical or corresponding parts will be represented by identical or similar reference numerals.

[0022] Figure 1A The schematic diagram of the state of a wind turbine generator in the prior art in a shutdown state is shown.

[0023] Figure 1B A schematic diagram of a wind turbine generator in a shutdown state that uses the method of the present invention to suppress tower vibration in one embodiment of the present invention is shown.

[0024] Figure 2 A schematic diagram showing the difference between blade states in the prior art and in the method of the present invention for suppressing tower vibration.

[0025] Figure 3 A schematic diagram showing the principle of a method for suppressing tower vibration in one embodiment of the present invention is shown.

[0026] Figure 4 A schematic flow chart of a method for suppressing tower vibration in one embodiment of the present invention is shown. DETAILED DESCRIPTION

[0027] It should be noted that the components in the figures may be shown exaggeratedly for the sake of illustration and are not necessarily true to scale. In the figures, identical or functionally identical components are provided with the same reference numerals.

[0028] In the present invention, unless otherwise specified, "arranged on", "arranged above" and "arranged above" do not exclude the presence of an intermediate between the two. In addition, "arranged on or above" merely indicates the relative positional relationship between two components, and in certain circumstances, such as after reversing the product direction, it can also be converted to "arranged below or below", and vice versa.

[0029] In the present invention, each embodiment is only intended to illustrate the aspects of the present invention and should not be construed as limiting.

[0030] In the present invention, unless otherwise specified, the quantifiers "a" and "an" do not exclude the presence of multiple elements.

[0031] It should also be noted that in the embodiments of the present invention, for the sake of clarity and simplicity, only a portion of the parts or components may be shown, but those of ordinary skill in the art will understand that under the teachings of the present invention, the required parts or components may be added according to the needs of the specific scenario. In addition, unless otherwise specified, the features in different embodiments of the present invention may be combined with each other. For example, a feature in the second embodiment may be used to replace a corresponding or functionally identical or similar feature in the first embodiment, and the resulting embodiment also falls within the disclosure scope or recorded scope of the present application.

[0032] It should also be noted that within the scope of the present invention, the terms "same", "equal", "equal to" and the like do not mean that the values ​​of the two are absolutely equal, but allow a certain reasonable error, that is, the terms also cover "substantially the same", "substantially equal", "substantially equal to". By analogy, in the present invention, the terms "perpendicular to", "parallel to", etc., which indicate directions, also cover the meanings of "substantially perpendicular to" and "substantially parallel to".

[0033] In the present invention, the term "temperature characteristic" refers to the deviation of an analog module of a semiconductor device caused by a change in external temperature.

[0034] In addition, the numbering of the steps of the methods of the present invention does not limit the execution order of the method steps. Unless otherwise specified, the method steps can be executed in different orders.

[0035] In the present invention, the controller can be implemented by software, hardware or firmware or a combination thereof. The controller can exist independently or be a part of a certain component.

[0036] The present invention will be further described below in conjunction with specific embodiments with reference to the accompanying drawings.

[0037] Figure 1A FIG. 1 shows a schematic diagram of a wind turbine generator in a shutdown state in the prior art. Figure 1A As shown, the wind turbine 100 may include a tower 101, a nacelle hub 102, and a plurality of blades 103, wherein the tower 101 supports the nacelle hub 102, and a plurality of blades 103 are arranged on the nacelle hub 102. In the prior art, the blades 103 are in a feathered state in a shutdown state, that is, the direction of the fore-aft vibration (fore-aft) generated by the tower 101 is consistent with the direction of the edgewise vibration (edgewise) generated by the blades 103, and is perpendicular to the direction of the flapwise vibration (flap wise) generated by the blades.

[0038] Figure 1BFIG. 1 is a schematic diagram showing a state of a wind turbine generator in a shutdown state that uses the method of the present invention to suppress tower vibration in an embodiment of the present invention. Figure 1B As shown, the angle between the direction of the flapping vibration of the blades 103 of the wind turbine 100 using the method of the present invention and the direction of the front-to-back vibration of the tower 101 is not perpendicular.

[0039] Figure 2 A schematic diagram showing the difference in blade states between the prior art and the method of the present invention for suppressing tower vibration is shown, wherein changes in tower and blade states caused by blade swing 201 in the prior art and blade flapping vibration 202 based on the pitch strategy can be seen.

[0040] The wind receiving area of ​​the blade 103 in the direction of flapping vibration is much larger than the wind receiving area in the swinging direction. Therefore, the aerodynamic damping generated by the blade 103 when flapping vibration occurs is large, while the aerodynamic damping generated when swinging vibration occurs is small.

[0041] for Figure 1A In the wind turbine 100 shown in the prior art that does not adopt the method of the present invention, the swing direction of the blades 103 is consistent with the direction of the front-to-back vibration of the tower 101. When the tower 101 vibrates in the front-to-back direction, since the amplitude of the swing direction of the blades 103 is small, the aerodynamic damping is weak and the front-to-back vibration of the tower 101 cannot be effectively suppressed.

[0042] And for Figure 1B In the wind turbine 100 shown in the figure that adopts the method of the present invention, the angle between the direction of the flapping vibration of the blade 103 and the direction of the front-to-back vibration of the tower 101 is not perpendicular but relatively close. When the tower 101 vibrates in the front-to-back direction, the amplitude of the flapping vibration of the blade 103 is large and generates strong aerodynamic damping, so the front-to-back vibration of the tower 101 can be effectively suppressed.

[0043] It should be noted that the tower vibration of a wind turbine generally includes first-order vibration and second-order vibration. The embodiments of the present invention can effectively suppress the second-order vibration and can also be applied to suppress the first-order vibration.

[0044] Figure 4 FIG. 1 is a flow chart showing a method for suppressing tower vibration in one embodiment of the present invention. Figure 4 As shown, the method may include:

[0045] Step 401, pitching the blades 103 so that the direction of the flapping vibration generated by the blades 103 is not perpendicular to the direction of the vibration of the tower 101; and

[0046] Step 402 : configuring the frequency of the flapping vibration of the blade 103 to be close to the frequency of the vibration of the tower 101 .

[0047] Figure 3 The schematic diagram of the principle of a method for suppressing tower vibration in an embodiment of the present invention is shown, wherein when the tower 101 vibrates, if the vibration frequency of the blade 103 is close to the vibration frequency of the tower 101, the blade 103 will vibrate with a large amplitude, thereby generating more aerodynamic damping to suppress the vibration of the tower 101. However, since the aerodynamic damping generated by the swing of the blade 103 is very small, when the pitch change strategy is not adopted, the vibration reduction effect of the blade 103 on the tower 101 is very small. In the present invention, based on the pitch change strategy, the direction of the flapping vibration of the blade 103 is close to the direction of the front-to-back vibration of the tower 101, and combined with modal analysis, the flapping vibration frequency of the blade close to the vibration frequency of the tower 101 is found. At this time, the front-to-back vibration of the tower 101 will induce a large-amplitude flapping vibration of the blade 103 in the same direction, thereby generating a large aerodynamic damping, effectively suppressing the vibration of the tower 101.

[0048] In a preferred use example of the present invention, the pitch change strategy includes:

[0049] Step 1: Perform modal analysis on the tower 101 and the blade 103 , and identify the proximity between the flapping vibration frequency of the blade 103 and the vibration frequency of the tower 101 based on the modal analysis results of the tower 101 and the blade 103 .

[0050] Step 2: Setting the blade angle so that the flapping vibration mode of the blade 103 in the modal analysis result has a significant vibration response in the front-rear vibration direction of the tower 101 to meet the requirements for aerodynamic damping.

[0051] Step 3: Based on step 1 and step 2, when the amplitude of the flapping vibration of the blade in the front-to-back vibration direction of the tower 101 is small, it is necessary to increase the pitch angle of the blade 103 or increase the number of the blades 103 using the pitch scheme; when the amplitude of the flapping vibration of the blade 103 in the front-to-back vibration direction of the tower 101 is large, the pitch angle of the blade 103 may be appropriately reduced or the number of the blades 103 using the pitch scheme may be reduced. For example, when the amplitude of the flapping vibration of the blade 103 in the front-to-back vibration direction of the tower 101 is less than a first value, the pitch angle of the blade 103 may be increased or the number of the blades 103 using the pitch scheme may be increased; and when the amplitude of the flapping vibration of the blade 103 in the front-to-back vibration direction of the tower 101 is greater than a second value, the pitch angle of the blade 103 may be reduced or the number of the blades 103 using the pitch scheme may be increased. The first value and the second value may be determined based on the vibration amplitude requirement of the fatigue index in the tower design.

[0052] Step 4: After determining the blade angle setting, check the aerodynamic torque and damping in the torsional direction of the wind rotor to ensure that the speed of the wind rotor is controllable.

[0053] Step 5: Based on the design working conditions of the wind turbine, check the ultimate load of the wind turbine under the variable pitch strategy, and screen the variable pitch parameter results that meet the requirements.

[0054] Although various embodiments of the present invention are described above, it should be understood that they are presented as examples only and not as limitations. It is obvious to those skilled in the relevant art that various combinations, modifications and changes can be made thereto without departing from the spirit and scope of the present invention. Therefore, the breadth and scope of the present invention disclosed herein should not be limited by the exemplary embodiments disclosed above, but should only be defined according to the attached claims and their equivalents.

Claims

1. A method for suppressing tower vibration, characterized in that: The method comprises: Pitching the blades of the wind turbine generator so that the direction of flapping vibration generated by the blades is not perpendicular to the direction of tower vibration of the wind turbine generator; and The frequency of the flapping vibration of the blade is configured to be close to the frequency of vibration of the tower, wherein close means that the absolute value of the difference between the frequency of the flapping vibration of the blade and the frequency of vibration of the tower is less than 30% of the absolute value of the smaller one of the frequency of the flapping vibration of the blade and the frequency of vibration of the tower.

2. The method according to claim 1, characterized in that The vibration includes first-order vibration and second-order vibration.

3. The method for suppressing tower vibration according to claim 1, characterized in that: Modal analysis is performed on the blade and the tower to determine the frequency of flapping vibration of the blade and the frequency of vibration of the tower.

4. The method for suppressing tower vibration according to claim 2, characterized in that: The blade angle of the wind turbine is configured so that the blade generates a flapping vibration response in the direction of the tower vibration.

5. The method for suppressing tower vibration according to claim 3, characterized in that: When the amplitude of the flapping vibration of the blade in the tower vibration direction is less than a first value, increasing the pitch angle of the blade or increasing the number of the blades for pitch change; as well as When the amplitude of the flapping vibration of the blade in the tower vibration direction is greater than a second value, the pitch angle of the blade is reduced or the number of the blades with pitch is increased, wherein the second value is greater than the first value.

6. The method for suppressing tower vibration according to claim 4, characterized in that: The aerodynamic torque and damping of the wind rotor of the wind turbine generator in the torsional direction are checked so that the rotation speed of the wind rotor can be controlled.

7. The method for suppressing tower vibration according to claim 5, characterized in that: The ultimate load of the wind turbine is checked.

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