vibration damping of a structure

Abstract

The invention relates to a partially assembled structure in the form of a structure comprising a wind turbine tower, a nacelle arranged on the wind turbine tower, and a vibration attenuator attached to the nacelle for attenuating vibrations of the combined wind turbine tower and nacelle in a selected frequency range, wherein the vibration attenuator is operatively connected to a main shaft of the nacelle or wherein the vibration attenuator is attached to the nacelle via a nacelle transportation interface. The invention further relates to a method of constructing a wind turbine and a method for attenuating eddy current induced vibrations of a combined wind turbine tower and nacelle in a selected frequency range.

Description

[0001] This application is a divisional application of the invention patent application filed on May 6, 2020, with application number 202080047944.8 (international application number: PCT / DK2020 / 050135) and entitled "Vibration Attenuation of Structure". Technical Field

[0002] This invention relates to a method for attenuating vibrations in a structure, including a wind turbine tower and a nacelle disposed on the wind turbine tower. In particular, this invention relates to a method for attenuating vibrations within a selected frequency range. Background Technology

[0003] During the construction phase of a wind turbine, steady winds can cause the wind turbine tower, on which the nacelle is mounted, to vibrate in a fundamental frequency mode due to eddy-induced vibrations. These eddy-induced vibrations are highly undesirable because they can damage and / or shorten the lifespan of the wind turbine tower and / or the nacelle mounted on it.

[0004] Therefore, there is a need for a damping device and associated method that can be used during periods when the construction of a wind turbine cannot be completed for some reason.

[0005] Therefore, the object of embodiments of the present invention is to provide a method for attenuating vibrations in a structure including a wind turbine tower and a nacelle disposed thereon. Summary of the Invention

[0006] The above-mentioned objective is achieved by providing a structure in the first aspect, the structure comprising a wind turbine tower, a nacelle disposed on the wind turbine tower, and a vibration damper attached to the nacelle for attenuating vibrations of the combined wind turbine tower and nacelle within a selected frequency range, wherein the vibration damper is operatively connected to the main shaft of the nacelle.

[0007] Therefore, in a first aspect, the present invention relates to a partially assembled wind turbine having a structure comprising a wind turbine tower and a nacelle disposed on the wind turbine tower. Furthermore, a vibration damper is provided for damping undesirable eddy current-induced vibrations in such a structure, since such eddy current-induced vibrations can potentially damage and thereby shorten the lifespan of the structure.

[0008] In embodiments of the present invention, the vibration attenuator may be selected from a pendulum attenuator, a friction attenuator, a magnetic attenuator, or a combination of vibration attenuators of the above types.

[0009] In embodiments of the invention, the vibration attenuator can be a passive attenuator. In this embodiment, the attenuator frequency can be substantially constant during use. The attenuator frequency can be adjusted before or shortly after installation.

[0010] In embodiments of the present invention, the vibration damper can be an actively adjustable passive damper.

[0011] The vibration damper frequency can be actively adjusted during operation based on feedback from acceleration sensors located within the damper or associated with the structure. This enables the vibration damper to operate autonomously to adapt to the frequency of a specific structure without user input.

[0012] Vibration dampers may not be considered permanent installations because they are only installed for a period of time when the wind turbine's construction cannot be completed for some reason. Therefore, the installation of vibration dampers can be considered temporary.

[0013] As described above, the vibration damper is operatively connected to the spindle of the nacelle. The term "operatively connected" should be understood to mean that the spindle directly or indirectly bears the weight of the vibration damper. As will become clear from the following discussion, this is advantageous for various reasons, including: the spindle has been sized to handle heavy loads and the operative connection of the vibration damper to the spindle is easily accessible to it.

[0014] Without a hub fixed to the main shaft of the engine nacelle, the vibration damper can be directly fixed to the main shaft. The term "directly" here should be understood to mean that the vibration damper can be fixed to the main shaft via an adapter and attachment devices on the vibration damper. With a hub fixed to the main shaft, the vibration damper can be fixed to the hub. For example, the vibration damper can be fixed to the blade bearing of the hub.

[0015] In the case of pitchable blades, the blade bearing can be a pitch bearing.

[0016] Furthermore, the above objective is achieved by providing a structure in the second aspect, which includes a wind turbine tower and a nacelle disposed on the wind turbine tower, and a vibration attenuator attached to the nacelle for attenuating vibrations of the combined wind turbine tower and nacelle within a selected frequency range, wherein the vibration attenuator is attached to the nacelle via a nacelle transport interface.

[0017] The cabin transport interface may include at least one hard point. The hard point may be configured to secure the cabin to various transport vessels or vehicles during transport. The at least one hard point may be part of the cabin structure and thus capable of transferring loads to the cabin structure. Vibration dampers and the cabin transport interface may include cooperative attachment devices.

[0018] As described above, the wind turbine tower with the nacelle mounted thereon can vibrate in a fundamental frequency mode due to vibrations caused by eddies. The fundamental frequency mode and the frequency range selected therefrom can be between 0.05 Hz and 0.50 Hz, such as between 0.05 Hz and 0.40 Hz, such as between 0.05 Hz and 0.30 Hz, such as between 0.05 Hz and 0.25 Hz.

[0019] Vibration attenuators may include multidirectional vibration attenuators configured to provide attenuation along multiple attenuation directions. If a vibration attenuator includes a multidirectional vibration attenuator, the vibration attenuator can operate as a stand-alone device, i.e., no additional equipment is required.

[0020] Alternatively, the vibration damper may include a unidirectional vibration damper configured to provide attenuation along a single attenuation direction. In cases where the vibration damper includes a unidirectional vibration damper, a means configured to rotate the nacelle may be further provided. This means rotates the nacelle to align the vibration of the structure with the single attenuation direction of the unidirectional vibration damper. The means configured to rotate the nacelle may include a drive unit and a controller configured to automatically align the vibration of the structure with the single attenuation direction of the unidirectional vibration damper in real time. The drive unit may include a controllable motor, and the controller may execute a suitable control algorithm that automatically aligns the attenuation direction of the vibration damper with the vibration direction of the wind turbine tower / nacelle structure. The control algorithm may apply various input parameters, such as inputs from accelerometers.

[0021] In a third aspect, the present invention relates to a method for attenuating vibrations in a selected frequency range of a structure, the structure including a wind turbine tower and a nacelle disposed on the wind turbine tower, the method comprising the step of temporarily attaching a vibration damper to the nacelle by operatively connecting the vibration damper to the main shaft of the nacelle.

[0022] Furthermore, the term "operationally connected" should be considered to refer to the spindle directly or indirectly bearing the weight of the vibration damper.

[0023] The steps of attaching the vibration damper to the nacelle may include the step of directly fixing the vibration damper to the spindle. The term "directly" here should be understood as being handled in accordance with the first aspect.

[0024] The structure may further include a hub fixed to the main shaft. In this case, the step of attaching the vibration damper to the nacelle may include the step of fixing the vibration damper to the hub.

[0025] In particular, the vibration damper can be mounted to the blade bearing of the hub. As already mentioned, it is advantageous to mount the vibration damper directly to the spindle or hub, as these are sized to handle heavy loads and are easily accessible.

[0026] The fundamental frequency mode to be attenuated and therefore the selected frequency range can be between 0.05Hz and 0.50Hz, such as between 0.05Hz and 0.40Hz, such as between 0.05Hz and 0.30Hz, such as between 0.05Hz and 0.25Hz.

[0027] In a fourth aspect, the present invention relates to a method for attenuating vibrations in a selected frequency range of a structure, the structure including a wind turbine tower and a nacelle disposed on the wind turbine tower, the method comprising the step of temporarily attaching a vibration attenuator to the nacelle via a nacelle transport interface.

[0028] As discussed with respect to the second aspect, the cabin transport interface may include at least one hard point. The at least one hard point may be configured to secure the cabin to various transport vessels or vehicles during transport. The at least one hard point may be part of the cabin structure and thus capable of transferring loads to the cabin structure. Vibration dampers and the cabin transport interface include cooperating attachment devices.

[0029] Vibration attenuators may include multidirectional vibration attenuators configured to provide attenuation along multiple attenuation directions, or vibration attenuators may include unidirectional vibration attenuators configured to provide attenuation along a single attenuation direction.

[0030] In cases where the vibration damper includes a unidirectional vibration damper, the method may further include the step of rotating the nacelle to align the vibration of the structure with a single damping direction of the unidirectional vibration damper. The step of rotating the nacelle to align the vibration of the structure with a single damping direction of the unidirectional vibration damper can be performed automatically and in real time. A suitable control algorithm for performing this alignment can apply different input parameters, such as inputs from accelerometers.

[0031] In a fifth aspect, the present invention relates to a method for constructing a wind turbine, the wind turbine including a wind turbine tower and a nacelle disposed on the wind turbine tower. The nacelle includes a main shaft, a hub fixed to the main shaft, and a set of rotor blades fixed to the hub. The method includes the following steps: partially assembling the wind turbine including the wind turbine tower and the nacelle disposed on the wind turbine tower and assembling the main shaft to the nacelle; installing a vibration damper on the nacelle during a period when the construction of the wind turbine cannot be completed for some reason; removing the vibration damper; and completing the construction of the wind turbine.

[0032] In one embodiment, the vibration damper is temporarily fixed to the hub, or to the main shaft of the nacelle, or to the nacelle transport interface.

[0033] In general, various aspects of the present invention can be combined and coupled in any possible manner within the scope of the invention. These and other aspects, features, and / or advantages of the invention will become apparent and elucidated with reference to the embodiments described below. Attached Figure Description

[0034] The invention will now be explained in more detail with reference to the accompanying drawings, in which: Figure 1 The assembled wind turbine is shown. Figure 2 The image shows a wind turbine tower and a nacelle mounted on the wind turbine tower. Figure 3 A vibration damper for a blade bearing fixed to a hub is shown. Figure 4 A vibration damper fixed to the spindle is shown, and Figure 5 A vibration damper is shown attached to the cabin via the cabin transport interface.

[0035] While the invention is susceptible to various modifications and alternatives, specific embodiments have been illustrated by way of example in the accompanying drawings and will be described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. Detailed Implementation

[0036] In a general sense, the present invention relates to a method for attenuating eddy current-induced vibrations in a structure comprising a wind turbine tower and a nacelle disposed on the wind turbine tower. More specifically, a method is provided for attenuating eddy current-induced vibrations in such a structure within a selected frequency range. The selected frequency range includes at least the fundamental frequency mode of the structure, which is typically in the range of 0.05 Hz to 0.25 Hz.

[0037] To counteract unwanted vibrations caused by eddy currents, vibration dampers are attached to the nacelle. Vibration dampers can be operatively connected to the nacelle via its main shaft or attached to the nacelle via a transport interface.

[0038] Vibration dampers can be operationally connected to the nacelle by temporarily fixing them directly to the main shaft or by temporarily fixing them to the hub (such as blade bearings fixed to the hub).

[0039] Alternatively, the attenuator can be temporarily attached to the cabin via a cooperating attachment device through at least one hard point in the cabin transport interface.

[0040] Now for reference Figure 1 The image depicts a wind turbine 100 comprising a wind turbine tower 101 and a nacelle 102 disposed on the wind turbine tower. Furthermore, a set of rotor blades 103 are fixed to a hub 104, which is fixed to the main shaft (not shown) of the nacelle 102. The main shaft is operatively connected to a generator (not shown) that converts mechanical energy into electrical energy.

[0041] If already addressed, steady winds may cause wind turbine towers with nacelles to vibrate at their fundamental frequency due to eddy-induced vibrations. The fundamental frequency is typically in the range of 0.05 Hz to 0.25 Hz. As will be discussed in further detail below, during periods when the construction of a wind turbine cannot be completed for some reason, the effects of eddy-induced vibrations can be counteracted by temporarily installing vibration dampers (possibly in combination with automatic yaw devices).

[0042] Figure 2A partially assembled wind turbine 200 is shown, comprising a wind turbine tower 201 and a nacelle 202 disposed on the wind turbine tower. Furthermore, a hub 203 is fixed to the main shaft (not shown) of the nacelle 202. However, the rotor blades are not yet fixed to the hub 203. As indicated by curve 205 and arrow 206, and as described above, the structure comprising the wind turbine tower 201 and the nacelle 202 disposed on the wind turbine tower tends to vibrate in a fundamental frequency mode between 0.05 Hz and 0.25 Hz due to eddy current-induced vibrations. Eddy current-induced vibrations may cause the structure comprising the wind turbine tower 201 and the nacelle 202 to move significantly away from baseline 204.

[0043] To mitigate the effects of vibrations caused by eddies, vibration dampers are installed during periods when the construction of the wind turbine cannot be completed for various reasons. In terms of implementation, the basic idea of ​​this invention is to temporarily fix the vibration damper to the hub 203 or the main shaft of the nacelle 202 before the hub 203 is fixed to the nacelle 202 or the nacelle transport interface, referring to... Figure 5 .

[0044] Vibration dampers can be attached to the hub before or after the hub is fixed to the main shaft. Typically, the hub is fixed to the main shaft after the nacelle has been installed on top of the wind turbine tower. Similarly, vibration dampers can be fixed to the main shaft before or after the nacelle has been installed on top of the wind turbine tower.

[0045] A vibration damper can be a multidirectional vibration damper capable of providing attenuation in multiple directions. Alternatively, a vibration damper can be a unidirectional vibration damper capable of providing attenuation in a single direction. The attenuation mechanism of a vibration damper can rely on a variety of attenuation mechanisms, including magnetic attenuation, frictional attenuation, and conventional mass / spring systems.

[0046] When the vibration attenuator is a multi-directional vibration attenuator, it can operate as a standalone device, i.e., no additional equipment is required. When the vibration attenuator is a unidirectional vibration attenuator, an automatic yaw device can be applied to yaw the nacelle, automatically aligning the attenuation axis of the attenuator with the vibration axis of the structure including the wind turbine tower and nacelle. A suitable control algorithm for automatically aligning the attenuation axis of the vibration attenuator with the vibration axis of the wind turbine tower / nacelle structure can be based on various input parameters, such as input from accelerometers.

[0047] Now for reference Figure 3 This illustrates a vibration damper 306 fixed to a wheel hub 303 via suitable adapters 305 and 307. (See diagram for reference.) Figure 3As shown, adapters 305 and 307 are fixed to one of the three blade bearings of hub 303. These blade bearings, each with an associated through opening 304, are each sized to handle the load of the rotor blades fastened to them.

[0048] The hub 303 is fixed to the main shaft (not shown) of the nacelle 302, which is mounted on top of the wind turbine tower 301. Figure 3 As shown, the hub 303 is positioned at a corner, such that the vibration damper 306 is at least symmetrically aligned with the width of the nacelle 302. The vibration damper 306 can be of the type disclosed above, i.e., a multi-directional vibration damper or a unidirectional vibration damper.

[0049] When the vibration attenuator 306 is a unidirectional vibration attenuator, an automatic yaw device can be used to yaw the nacelle 302 so that the attenuation axis of the vibration attenuator 306 is aligned with the vibration axis of the wind turbine tower / nacelle structure.

[0050] Now go to Figure 4 The diagram depicts a vibration damper 403 fixed to the main shaft 404 of a nacelle 402. The nacelle 402 is positioned on top of a wind turbine tower 401. Again, the vibration damper 403 can be of the type disclosed above, and in the case where the vibration damper 403 is a unidirectional vibration damper, an automatic yaw device can be applied to yaw the nacelle 402 so that the damping axis of the vibration damper 403 is aligned with the vibration axis of the wind turbine tower / nacelle structure.

[0051] Now for reference Figure 5 The vibration damper 505 is fixed to the cabin 502 via the cabin transport interface 504. For example... Figure 5 As shown, the nacelle 502 is arranged on top of the wind turbine tower 501. The hub 503 may optionally be fixed to the main shaft (not shown) of the nacelle 502. The vibration damper 505 may be of the type disclosed above, and in the case where the vibration damper 505 is a unidirectional vibration damper, an automatic yaw device may be applied to yaw the nacelle 502 so that the damping axis of the vibration damper 505 is aligned with the vibration axis of the wind turbine tower / nacelle structure. Figure 5 In this configuration, the vibration damper 505 is fixed to the cabin transport interface 504 located near the front end of the cabin 502. Alternatively, and as... Figure 5 As shown by the dashed line, the vibration damper 507 can be fixed to the cabin transport interface 506 located near the rear end of the cabin 502.

[0052] The cabin transport interfaces 504 and 506 may each include at least one hard point. The hard point is configured to secure the cabin 502 to various transport vessels or vehicles during transport. The at least one hard point may be part of the cabin structure and thus capable of transferring loads to the cabin structure. The vibration damper 505 and the cabin transport interface 504 may include cooperatively operating attachment devices.

Claims

1. A structure comprising a partially assembled wind turbine, said partially assembled wind turbine taking the form of a structure including a wind turbine tower, a nacelle disposed on said wind turbine tower, and a vibration damper attached to said nacelle, said vibration damper being used to attenuate vibrations of the combined wind turbine tower and nacelle within a selected frequency range, wherein, The vibration damper is operatively connected to the main shaft of the nacelle, or the vibration damper is attached to the nacelle via a nacelle transport interface.

2. The structure according to claim 1, wherein, The vibration damper is directly fixed to the spindle.

3. The structure according to claim 1, further comprising a hub fixed to the main shaft, and wherein, The vibration damper is fixed to the wheel hub.

4. The structure according to claim 3, wherein, The vibration damper is fixed to the blade bearing of the hub.

5. The structure according to any one of claims 1 to 4, wherein, The selected frequency range is between 0.05 Hz and 0.50 Hz, such as between 0.05 Hz and 0.40 Hz, such as between 0.05 Hz and 0.30 Hz, such as between 0.05 Hz and 0.25 Hz.

6. The structure according to any one of claims 1 to 5, wherein, The vibration damper includes a multidirectional vibration damper configured to provide damping along multiple damping directions.

7. The structure according to any one of claims 1 to 6, wherein, The vibration damper includes a unidirectional vibration damper configured to provide attenuation along a single attenuation direction.

8. The structure of claim 7, further comprising means configured to rotate the nacelle so as to align the vibration of the structure with the single attenuation direction of the unidirectional vibration attenuator.

9. The structure according to claim 8, wherein, The device configured to rotate the cabin includes a drive unit and a controller, the controller being configured to automatically align the vibrations of the structure with the single attenuation direction of the unidirectional vibration attenuator in real time.

10. A method for constructing a wind turbine, the wind turbine comprising a wind turbine tower, a nacelle disposed on the wind turbine tower, the nacelle comprising a main shaft, a hub fixed to the main shaft, and a set of rotor blades fixed to the hub, the method comprising the following steps: - Partially assemble the wind turbine, including the wind turbine tower and the nacelle arranged on the wind turbine tower, and assemble the main shaft to the nacelle. - During the period when the construction of the wind turbine cannot be completed for some reason, a vibration damper will be installed on the nacelle. - Remove the vibration damper, and - Complete the construction of the wind turbine.

11. The method according to claim 10, wherein, The vibration damper is temporarily fixed to the hub, or to the main shaft of the cabin, or to the cabin transport interface.

12. A method for attenuating vibrations in a selected frequency range of a structure, said structure including a wind turbine tower and a nacelle disposed on said wind turbine tower, the method comprising the steps of: The vibration damper is temporarily attached to the nacelle by operatively connecting it to the main shaft of the nacelle, or by temporarily attaching it to the nacelle via a nacelle transport interface.

13. The method according to claim 12, wherein, The step of attaching the vibration damper to the nacelle includes the step of directly fixing the vibration damper to the spindle.

14. The method according to claim 12, wherein, The structure also includes a hub fixed to the main shaft, and the step of attaching the vibration damper to the nacelle includes attaching the vibration damper to the hub.

15. The method according to claim 14, wherein, The hub includes a blade bearing, and the step of attaching the vibration damper to the nacelle includes attaching the vibration damper to the blade bearing of the hub.

16. The method according to any one of claims 12 to 15, wherein, The vibration damper includes a unidirectional vibration damper configured to provide attenuation along a single attenuation direction, and the method further includes the step of rotating the nacelle to align the vibration of the structure with the single attenuation direction of the unidirectional vibration damper.

17. The method according to claim 16, wherein, The step of rotating the nacelle to align the vibration of the structure with the single attenuation direction of the unidirectional vibration attenuator is performed automatically and in real time.

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