Wind turbine with damper with tilting mechanism and method of damping vibrations in wind turbine

Abstract

A tubular structure for forming at least a portion of a wind turbine tower (18) of a wind turbine (10) having a vibration damper (22) includes an elongate tubular body having a first end, a second end, and a tower wall (46) extending between the first end and the second end. The first end is configured to be connected to a nacelle (24) of a wind turbine (10), and the tower wall (46) defines a longitudinal axis (20) of the tubular body. A vibration damper (22) having a central axis (64) is coupled to the tubular structure. The tubular structure includes a tilt mechanism (88) operably coupled to the vibration damper (22) and configured to change an orientation of a central axis (64) of the vibration damper (22) relative to a longitudinal axis (20) of the tubular body. A method of damping vibrations in such a tubular structure is also disclosed.

Description

Technical Field

[0001] The present invention relates generally to wind turbines and, more particularly, to a wind turbine tower, a vibration damper and a method for damping vibrations in a wind turbine. Background Art

[0002] Wind turbines are used to generate electrical energy using renewable resources without burning fossil fuels. Typically, wind turbines convert kinetic energy from wind into electricity. A horizontal axis wind turbine includes a tower and an energy generation unit located on top of the tower. The energy generation unit typically includes a nacelle for accommodating mechanical and electrical components (such as a generator), and a rotor that is operably connected to components in the nacelle through a main shaft extending from the nacelle. The rotor includes a central hub and a plurality of blades that extend radially from the central hub and are configured to interact with the wind to cause the rotation of the rotor. The rotor is supported on the main shaft, which is directly or indirectly operably connected to a generator housed in the nacelle. Therefore, when the wind forces the blades to rotate, the generator generates electrical energy. Wind turbines can be constructed on land or at sea at locations with significant wind.

[0003] To be economical, wind turbines must be able to withstand the forces caused by continuous vibration for a long time. Vibration can be caused by internal or external forces and includes oscillations or repeated displacements in the lateral, longitudinal and / or torsional directions of almost any amplitude and frequency depending on the source of vibration. Typically, the source of vibration can include any single or combination of wind acting on the tower (i.e., vortex generation), blade rotation passing through the tower, rotor rotation, nacelle yaw motion, nacelle imbalance, and imbalance in the gearbox and / or generator, etc., just to name a few examples. Offshore and near-shore installations provide an additional source of vibration - water movement. Whether the wind turbine is floating or on a foundation structure (e.g., a monopile) that is directly fixed to the seabed, water movement is an additional source of vibration. To make the conditions more difficult, there is usually a significant inconsistency between wind and waves. This may cause large loads in the left-right direction on the tower, which is usually not present in onshore installations. Forces from any vibration can cause fatigue damage to the wind turbine, and substantial fatigue damage exceeding the expected in the design can lead to a reduction in the service life of one or more of the wind turbine tower and / or its components.

[0004] Vibration at a specific frequency can cause resonance of one or more parts of a wind turbine, particularly in a wind turbine tower. Resonance where the vibration matches the natural frequency of a wind turbine is a potentially catastrophic event because the forces caused by the vibration may exceed the structural integrity of the wind turbine. Therefore, wind turbine designers consider vibration and specifically know the resonant frequency during the design process. Designers can modify the wind turbine structural design to avoid resonance during wind turbine operation. As an example, the tower wall thickness can be changed to modify the natural frequency of the wind turbine tower. Designers can include devices specifically designed to damp vibrations, either alternatively or in combination with structural modifications. These devices, known as vibration dampers or dampers, are generally active, semi-active or passive in their vibration damping. Active dampers apply force to the structure in the opposite direction of the vibration through a control system. Passive dampers are tuned to react to vibrations and absorb wind turbine vibrations of specific frequencies, and semi-active dampers combine the features of active dampers and passive dampers.

[0005] While wind turbines are generally commercially successful, it is desirable to extend the useful life of wind turbines. Accordingly, wind turbine manufacturers and operators seek improved wind turbines, particularly to improve energy production while overcoming current design limitations, including addressing fatigue damage from vibrations, and stabilizing wind turbine towers during energy production. Summary of the invention

[0006] To address these and other shortcomings, and in a first aspect of the present invention, a tubular structure for forming at least a portion of a wind turbine tower of a wind turbine having a vibration damper is disclosed. The tubular structure includes an elongated tubular body having a first end, a second end, and a tower wall extending between the first end and the second end. The first end is configured to be connected to a nacelle of the wind turbine, and the tower wall defines a longitudinal axis of the tubular body. A vibration damper having a central axis is coupled to the tubular structure, such as to the tower wall inside the tubular body. The tubular structure includes a tilting mechanism that is operably coupled to the vibration damper and is configured to change the orientation of the central axis of the vibration damper relative to the longitudinal axis of the tubular body. The tilting mechanism may be particularly beneficial when the wind turbine tower is tilted so that its longitudinal axis is not vertically aligned with gravity.

[0007] In one embodiment, the tilt mechanism may include a lateral adjustment mechanism configured to rotate the vibration damper about an axis perpendicular to the longitudinal axis. For example, the longitudinal axis may define a radial plane that intersects the vibration damper, and the tilt mechanism may include a radial adjustment mechanism configured to rotate the vibration damper about an axis perpendicular to the radial plane.

[0008] In one embodiment, the support assembly may be rigidly connected to the tower wall, and the vibration damper may further include a frame assembly slidably supported on the support assembly. The tilt mechanism may be operably coupled to the frame assembly and the support assembly, whereby operation of the tilt mechanism moves the frame assembly relative to the support assembly. In one embodiment, the frame assembly is pivotally fixed to the support assembly. Further, in one embodiment, the frame assembly may pivot within a plane in which the tilt mechanism changes the orientation of the central axis. In another embodiment, the tilt mechanism may be between the frame assembly and the support assembly.

[0009] In one embodiment, the support assembly may define a sliding surface on which the frame assembly is slidably supported. For example, the sliding surface may include an inner sliding plane perpendicular to the longitudinal axis and a first outer sliding plane and a second outer sliding plane on opposite sides of the inner sliding plane. Each outer sliding plane may form an obtuse angle with respect to the inner sliding plane. In addition, the slotted flange is pivotally fixed to the frame assembly and slidably engaged with each of the inner sliding plane and the outer sliding plane.

[0010] In one embodiment, the tilt mechanism may include a pair of supports, wherein one support is coupled to the frame assembly, the other support is coupled to the support assembly, and a threaded rod rotatably couples the pair of supports together. In this embodiment, rotation of the threaded rod changes the distance between the pair of supports.

[0011] In a second aspect of the invention, a wind turbine comprising a tubular structure according to the first aspect is disclosed. In one embodiment, the tubular structure may be a wind turbine tower or a part thereof. For example, in one embodiment, the tubular structure may comprise a wind turbine tower segment that is connected to other wind turbine tower segments to form a wind turbine tower. The wind turbine tower segment having the vibration damper is typically the segment closest to the nacelle of the wind turbine.

[0012] In yet another aspect of the present invention, a method of damping vibrations in a tubular structure configured to form at least a portion of a wind turbine tower of a wind turbine is disclosed. The tubular structure includes: an elongated tubular body having a first end, a second end, and a tower wall extending between the first end and the second end, the tower wall defining a longitudinal axis of the tubular body; and a vibration damper having a central axis and connected to the tower wall within the tubular body adjacent to the first end. The method includes: erecting the tubular structure so as to be supported at the second end of the tubular body, the longitudinal axis of the erected tubular body having a first orientation; and adjusting the vibration damper relative to the tower wall so that the central axis of the vibration damper has a second orientation relative to the longitudinal axis of the tubular body that is different from the first orientation.

[0013] In one embodiment, adjusting the vibration damper may further include determining an orientation of the longitudinal axis of the tubular body relative to gravity, and rotating the central axis of the vibration damper toward the orientation of gravity. In this embodiment, rotating the central axis of the vibration damper may include rotating the central axis of the vibration damper about an axis perpendicular to the longitudinal axis. In one embodiment, the longitudinal axis of the tubular body may define a radial plane that intersects the vibration damper, and rotating the central axis of the vibration damper may further include rotating the vibration damper about an axis perpendicular to the radial plane.

[0014] In one embodiment, the tubular body may include a support assembly, and the vibration damper may include a frame assembly slidably supported on the support assembly, and rotating the central axis of the vibration damper may further include sliding the frame assembly relative to the support assembly. In one embodiment, a plurality of fasteners may connect the frame assembly to the support assembly during operation of the vibration damper, and before rotating the central axis of the vibration damper, the method may further include loosening the plurality of fasteners, and after sliding the frame assembly relative to the support assembly, tightening the plurality of fasteners.

[0015] In one embodiment, a tilt mechanism may be operated between the support assembly and the frame assembly, and rotating the central axis of the vibration damper may further include operating the tilt mechanism. In one embodiment, the tilt mechanism may include: a pair of supports, wherein one of the supports is coupled to the frame assembly and the other support is coupled to the support assembly; and a threaded rod rotatably coupled to the pair of supports, and sliding the frame assembly relative to the support assembly may further include rotating the threaded rod to change the distance between the pair of supports. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with the general description of the invention given above and the detailed description given below, serve to explain the invention.

[0017] Figure 1 is a perspective view of a wind turbine according to an embodiment of the present invention;

[0018] Figure 2 and Figure 2A They are respectively depicting a vibration damper according to an embodiment of the present invention. Figure 1 a partial cross-sectional perspective view and a cross-sectional elevation view of a portion of a wind turbine tower;

[0019] Figure 3 It is along Figure 2A The section line 3-3 is taken Figure 2 and Figure 2A Plan view of wind turbine tower and vibration damper;

[0020] Figure 4 yes Figure 2 A front view of the vibration damper is shown;

[0021] Figure 5 It is along Figure 4 The section line 5-5 in Figure 4 A cross-sectional view of a vibration damper;

[0022] Figure 6 is a left perspective view of a vibration damper according to an embodiment of the present invention;

[0023] Figure 7 and Figure 8 yes Figure 4 A bottom perspective view of a vibration damper is shown illustrating the installation of the vibration damper according to one aspect of the present invention;

[0024] Fig. 9 , Fig.10 and Fig.11 are a perspective view, a plan view, and a front view, respectively, showing a portion of a tilt mechanism according to an embodiment;

[0025] Fig. 12A , Fig. 12B and Fig. 12C is a schematic elevation view during adjustment of the orientation of a vibration damper relative to a tower according to one embodiment of the present invention;

[0026] Fig.13 is an exploded view of the vibration damper with the pendulum separated from the frame assembly;

[0027] Fig.13A and Fig. 13B is a schematic diagram of the oscillation of a vibration damper;

[0028] Fig.14 is an exploded view showing the separation of the pendulum and the end stop removed from the suspended pendulum;

[0029] Fig.15A and Fig. 15B It is a diagram of the amount of activity that the pendulum moves;

[0030] Fig.16 is a cross-sectional view of a pendulum showing an end stop according to an embodiment of the present invention;

[0031] Fig.17 is a cross-section of an end stop according to one embodiment of the present invention;

[0032] Fig.18is a graph of damping versus acceleration for a vibration damper without end stops and with end stops according to an embodiment of the present invention;

[0033] Fig.19 is a cross-sectional view of a pendulum showing an end stop and a locking mechanism according to an embodiment of the present invention;

[0034] Fig. 20 is a cross-sectional view of a pendulum showing a locking mechanism according to an embodiment of the present invention;

[0035] Fig.21A , Fig. 21B and Fig. 21C is a schematic cross-sectional view of the locking mechanism, wherein: Fig.21A Describes the unlocked position and Fig. 21B and Fig. 21C Depicts the locked position; and

[0036] Fig. 22 is a mathematical model of a vibration damper according to an embodiment of the present invention. DETAILED DESCRIPTION

[0037] Referring generally to the accompanying drawings, aspects of the present invention relate to a vibration damper having a simple, compact and robust design. Advantageously, embodiments of the present invention are installed in a wind turbine tower, but can be used to damp vibrations during all stages of transportation and installation of the tower in an upright orientation and during operation of the tower. As described in detail herein, the vibration damper is installed and operated within a confined space in the upper portion of the tower, while allowing maintenance personnel to access other equipment installed at higher locations in the tower (such as in the nacelle). It may not be necessary to disable or limit damper operation while service personnel are in the wind turbine. For more consistent and efficient operation, the exemplary vibration damper is adjustable to the orientation of the tower both at the time of installation and over the service life of the tower. The vibration damper also greatly simplifies the service and maintenance procedures of the damper itself. Other advantages and benefits of the exemplary vibration damper are described herein.

[0038] For these and other purposes and with reference to Figure 1 , an exemplary embodiment of the present invention includes a wind turbine 10 that can be installed in an offshore location, as shown. In this location, the wind turbine 10 includes a transition piece 12 that extends from a foundation pile (not shown) fixed in the seabed to a position above the ocean 14. Embodiments of the present invention are not limited to Figure 112 is shown. Other exemplary transition pieces may be used in the construction of wind turbine 10 in accordance with embodiments of the present invention. Another such exemplary transition piece may be referred to as an extended transition piece. Furthermore, although an offshore installation is shown, embodiments of the present invention may be applied to onshore and offshore installations that vary in the type of foundation to which wind turbine 10 is secured.

[0039] Continue to refer to Figure 1 , the energy generation unit 16 is raised above the transition piece 12 by a wind turbine tower 18. The exemplary tower 18 is modular and includes three tubular sections 18a, 18b and 18c, each having an elongated tubular structure having a wall defining a longitudinal axis. Each section has opposite ends (not labeled). When the three sections 18a-18c are assembled end to end, they together define a tower 18 having a tower longitudinal axis 20, and the energy generation unit 16 rotates around the tower longitudinal axis 20 via a yaw mechanism (not shown). Although a modular tower is shown, embodiments of the present invention are not limited to modular towers. During its installation, the wind turbine tower 18 is fixed to the transition piece 12 at one section 18a, and the energy generation unit 16 is installed at the opposite end of the wind turbine tower 18 on the section 18c.

[0040] The vibration damper 22 is mounted as high as possible within the wind turbine tower 18, such as in the uppermost portion of the section 18c. In this regard, the damper 22 is positioned as close as possible to the antinode of the first vibration mode in the tower 18. The antinode of the first vibration mode is at / near the highest level of the tower 18. If the damper 22 is used for damping the second vibration mode, the damper 22 or an additional damper may be placed as close as possible to the antinode of the second vibration mode. In one embodiment, the vibration damper 22 is located within ±15% of the height of the tower 18 or tower sections 18a-18c of the selected antinode. As a further example, the vibration damper 22 is located within ±10% of the height of the tower 18 or tower sections 18a-18c of the selected antinode, and preferably within ±5% of the height of the tower 18 or tower sections 18a-18c of the selected antinode. In one embodiment, the vibration damper 22 is installed within the upper 30% of the wind turbine tower 18 (e.g., in section 18c) to provide effective damping of tower vibrations. As a further example, the damper 22 can be coupled to the tower section 18c, preferably no more than about 15% from the upper end of the tower section 18c, and even more preferably no more than about 5% from the upper end of the tower section 18c. With respect to a tower section (such as tower section 18c), the damper 22 can be installed at a distance from the upper end that is no more than 50% of the height of the tower section 18c, preferably no more than about 40% of the height of the tower section 18c, and even more preferably no more than about 30% of the height of the tower section 18c. By placing the vibration damper 22 as high as possible in the wind turbine tower 18, the vibration can be more effectively damped using a smaller mass (e.g., a lower weight pendulum) in the vibration damper 22. The top of the tower is usually very crowded, and the vibration damper is therefore usually relocated to the lower part of the tower. This in turn requires a larger pendulum mass to achieve damping.

[0041] The energy generation unit 16 includes the components of the wind turbine 10 that convert the kinetic energy of the wind into electrical energy. In this regard, the energy generation unit 16 generally includes a housing or nacelle 24 and a rotor 26 having a plurality of blades 28 (e.g., three blades) mounted to a central hub 30 and extending radially therefrom, and a generator (not shown) for converting mechanical energy into electrical energy. The wind turbine blades 28 interact with the wind to rotate the rotor 26 and thereby rotate the generator. The energy generation unit 16 may also include a drive train (not shown) including a gear arrangement interconnecting the rotor 26 and the generator. The generator and the majority of the drive train may be positioned inside the nacelle 24 of the wind turbine 10. In addition to the generator, the nacelle 24 generally houses various electrical equipment and components required to convert wind energy into electrical energy and various components required to operate, control, and optimize the performance of the wind turbine 10. The generator in nacelle 24 , while producing electrical energy for commercial distribution, also provides power for operation of wind turbine 10 , including powering various components in nacelle 24 and at lower levels down tower 18 , including on platform 32 .

[0042] Although embodiments of the vibration damper 22 are shown as being installed in the tower 18 and described in conjunction with the operation of the wind turbine 10, the vibration dampers described herein may be utilized during storage and transportation of one or more tower segments 18a, 18b, 18c to a location for installation of the wind turbine 10 and during installation of the wind turbine 10 prior to installation of the nacelle 24 and rotor 26. This may be advantageous because there is a risk of eddy current induced vibrations on the tower 18 or on any individual of the segments 18a-18c prior to installation of the nacelle 24. Thus, after construction of the segments 18a-18c, the vibration damper 22 may be installed to absorb tower vibrations and reduce fatigue on the segments 18a-18c even prior to installation of the wind turbine 10. Thus, once erected, the vibration damper 22 of the present invention may also be installed and operated in one or more tower segments 18a-18c. For example, tower sections 18a-18c are typically erected separately prior to assembly of tower 18, such as during storage (e.g., erected quayside on supports awaiting transport) and / or during transport (e.g., erected on a transport vessel) and prior to installation. Vibration dampers 22 may optionally be disassembled after wind turbine 10 has been assembled and reused in another tower.

[0043] refer to Figure 1 , at a location above the ocean 14, an exterior platform 32 provides access to the interior of the wind turbine tower 18 via a doorway 34. Once inside the wind turbine tower 18, reference is made to Figure 1 and Figure 2, maintenance personnel climb up the internal ladder 36 to access the interior of the nacelle 24. Between the nacelle 24 and the external platform 32, the tower 18 generally includes one or more internal platforms. For example, the ladder 36 leads to the internal platform 40, such as Figure 2 As shown. The internal platform 40 is at the uppermost end of the tower segment 18c. Specifically, the platform 40 is located near the nacelle 24, which is rotatably fixed to the flange 38, which defines the upper end of the tower 18 (and may be one end of the tower segment 18c). The internal platform 40 substantially covers the entire area within the cross-section of the tower segment 18c. Another ladder 42 extends from the platform 40 to another platform 44. In the embodiment shown, the interior of the nacelle 24 can be directly accessed from the platform 44. Therefore, the internal platform 40 is two horizontal planes below the nacelle 24. Devices for maintenance (such as a maintenance elevator (not labeled)) and operation of the wind turbine 10 can be located on the platform 40 and / or the platform 44 and can be accessed by maintenance personnel via the ladders 36 and 42.

[0044] like Figure 2 , Figure 2A and Figure 3 As shown, in an exemplary embodiment, the vibration damper 22 is accessible at the platform 40 and is located in the vertical space between the internal platforms 40 and 44. With respect to the horizontal direction, the vibration damper 22 is located between the tower longitudinal axis 20 and the outer tower wall 46 forming the tower section 18c. In this regard, the vibration damper 22 can be located at a sufficiently safe distance opposite to the ladders 36 and 42 with respect to the tower longitudinal axis 20. Then, the service personnel can climb onto the platform 40 to operate the device and access the ladder 42. When the vibration damper 22 is operable, access to the interior of the nacelle 24 is not prohibited.

[0045] Furthermore, the vibration damper 22 does not inhibit the wiring required for efficient operation of the wind turbine 10. For example, the openings 50, 52 in the platforms 40 and 44 are respectively aligned with the center of the tower longitudinal axis 20. The high voltage cables (not shown) of the electrical connectors to which the generator in the nacelle 24 is electrically coupled down the tower 18 extend through the openings 50, 52. Advantageously, the vibration damper 22 is mounted on one side of the openings 50, 52. Thus, the vibration damper 22 is completely contained on one side of the tower 18, so there is no need to rewire or change the location of the openings 50, 52 when the vibration damper 22 is used. By way of example only, the footprint of the vibration damper 22 on the platform 40 is half or less of the area of ​​the platform 40. With this arrangement, the exemplary vibration damper described herein can be used on the topmost floors of existing wind turbine towers in confined spaces and can be mounted between the centrally located existing high voltage cables and the tower wall. The exemplary vibration damper 22 may be attached to the tower wall 46 , the platform 40 , and / or the platform 44 , or to a combination of the tower wall 46 and one or both of the platforms 40 and 44 .

[0046] refer to Figure 3 , Figure 4 and Figure 5 In the exemplary embodiment, the vibration damper 22 includes a frame assembly 56 for movably suspending an upper mass 66 and a lower mass 74 in a spaced relationship with each other. The upper mass 66 forms a suspended pendulum and the lower mass 74 forms an upright pendulum, as described below. To achieve this arrangement, the frame assembly 56 includes an upper frame 60 and a lower frame 62 for movably suspending the masses 66 and 74, respectively. At the equilibrium position of the masses 66 and 74 in the frame assembly 56, the masses 66 and 74 define a central axis 64. Although described below, in the exemplary embodiment, the orientation of the frame assembly 56 can be adjusted relative to the tower 18 so that the orientation of the central axis 64 can be changed at any time during and after the installation of the vibration damper 22.

[0047] refer to Figure 5 , when the masses 66, 74 are in their balanced resting positions (i.e., not oscillating), the center of mass 66a of the upper mass 66 and the center of mass 74a of the lower mass 74 define the central axis 64 of the vibration damper 22. The central axis 64 is shown as being spaced apart from but substantially parallel to the longitudinal axis 20 of the tower 18. In other words, the central axis 64 is offset from the longitudinal axis 20 in a direction toward the wall 46. As shown in FIG. Figure 2 , Figure 2A , Figure 3 and Figure 5 4, the center axis 64 is radially spaced outward from the longitudinal axis 20. With this arrangement, the masses 66 and 74 are isolated to one side of the space available in the tower section 18c at the interior platform 40. That is, the masses 66 and 74 only occupy space on one side of the opening 50 between the opening 50 and the tower wall 46. As described below with respect to oscillations of the vibration damper 22, neither of the masses 66 and 74 is displaced (e.g., swung) into the space between the opening 50 and the opening 52, so that the high voltage cables extending between the opening 50 and the opening 52 are not disturbed by the vibration damper 22 when the vibration damper 22 damps tower vibrations.

[0048] In addition, if Figure 2 , Figure 3 and Figure 6 As shown, the shape of the masses 66, 74 facilitates a compact, space-saving design. Figure 3 In the exemplary embodiment shown, masses 66 and 74 are similarly shaped, wherein each mass has a bean shape when viewed along central axis 64. In other words, when viewed in cross-section, masses 66 and 74 may have an annular arc shape. This is generally due to Figure 354 is shown to trace the centerline of the annular arc shape of the masses 66 and 74. As an example, the arc 54 has an arc amount equal to or less than 180°, and as a further example, the arc 54 may have an arc amount of 60° to 145° or more specifically 90° to 150° or substantially 120°. In the exemplary embodiment shown, the arc 54 of each mass 66, 74 shares a common center with the tower longitudinal axis 20, and may be positioned so that the arc 54 equally divides the distance between the outer wall 46 and the opening 50. In other words, the masses 66 and 74 have similar curvatures in a plane perpendicular to the longitudinal axis 20 to the outer wall 46, and are each evenly spaced from the outer wall 46 and the opening 50 along their respective arc lengths. This arrangement maximizes the operating space for the masses 66 and 74 to move during the oscillation described below. Also, when viewed in a radial direction, such as from the longitudinal axis 20, the masses 66 and 74 are generally rectangular in shape. However, embodiments of the present invention are not limited to the cross-sectional and radial configurations shown. Specifically, masses 66 and 74 may each or one or the other may vary in their spacing between outer wall 46 and opening 50 relative to outer wall 46. This may occur if masses 66 and / or masses 74 have a non-annular cross-sectional configuration. Thus, while exemplary vibration damper 22 is shown as having annular arcuate masses 66 and 74 in a plane perpendicular to axis 20, embodiments of the present invention are not limited to this configuration. Other configurations contemplated include any regular volumetric shape that is symmetrical, such as a circular cross-sectional shape.

[0049] like Figure 4 , Figure 5 and Figure 6 As shown, frame assembly 56 movably secures masses 66 and 74 to tower 18. Frame assembly 56 movably couples upper mass 66 to upper frame 60. In an exemplary embodiment, a swing rod 70 having a universal joint 72 at each end thereof movably couples upper mass 66 to upper frame 60. When exposed to vibrations of tower 18, swing rod 70 and universal joint 72 define a generally arcuate path of travel for the swinging motion of upper mass 66. The orientation of upper mass 66 and swing rod 70 and universal joint 72 form a suspended pendulum and is described below.

[0050] In the exemplary embodiment, the frame assembly 56 movably couples the lower mass 74 to the lower frame 62. Similar to the upper mass 66, the lower mass 74 is movably coupled to the lower frame 62 via the rocker 70 and the universal joint 72. The rocker 70 and the universal joint 72 define a generally arcuate path of motion for the swinging motion of the lower mass 74. The orientation of the lower mass 74 and the rocker 70 and the universal joint 72 forms an upright pendulum, also referred to as an inverted pendulum, and is described below. As shown in the exemplary embodiment, the vibration damper 22 is a passively tuned double pendulum mass damper.

[0051] The lower mass 74 and the upper mass 66 are each capable of oscillating along their arcuate paths relative to the frame assembly 56. These arcuate paths are defined by the pendulum rods 70. In one embodiment, the pendulum rods 70 have the same length in a suspended pendulum and in an upright pendulum. The arcuate movements of the masses 66 and 74 are therefore mirror images of each other. That is, when the masses 66 and 74 swing outward from equilibrium, the upper arc path includes an upward displacement or directional component to the movement of the upper mass 66, and the lower arc path includes a downward displacement or directional component to the movement of the lower mass 74. Although the exemplary embodiment depicts three pendulum rods 70 and multiple universal joints 72, embodiments of the present invention are not limited to any particular configuration and / or a particular number of connections between the upper mass 66 and the frame assembly 56 or between the lower mass 74 and the frame assembly 56.

[0052] Continue to refer Figure 4 , Figure 5 and Figure 6 , frame assembly 56 has a C-shaped configuration. From each end of the "C", one of masses 66 and 74 is fixed. A gap 78 at an equilibrium position is maintained between upper mass 66 and lower mass 74. As described below, the arcuate movement of masses 66, 74 in response to tower vibration causes the separation between masses 66 and 74 to change from the equilibrium gap 78. That is, the separation increases as the vibration of tower 18 increases. With this relative movement capability, vibration damper 22 is able to damp the vibration of tower 18.

[0053] In the exemplary embodiment and with reference to Figure 4 , Figure 5 and Figure 6 , the frame assembly 56 also includes an interconnecting frame member 92 that extends from the upper frame 60 to the lower frame 62 and thus provides a rigid connection between the two opposing frames 60, 62 to form the C-shape of the assembly 56. In the exemplary embodiment, the interconnecting frame member 92 has an upper trident-shaped member 94 and a lower trident-shaped member 96 that engage a backbone member 98. This configuration distributes the extreme loads generated by the masses 66, 74 to maintain the gap 78 between the two masses 66, 74 during balance and oscillation.

[0054] refer to Figure 4 , Figure 5 and Figure 6 , the vibration damper 22 includes a pair of dampers. For example, a linear damper 100 may be pivotally coupled to the frame member 92 at one end. Thus, as the masses 66, 74 swing along their arcuate paths, they cause movement of the linear damper 100. The linear damper 100 resists the oscillating motion of the masses 66, 74 and damps the vibration.

[0055] Reference Figure 4 , Figure 5 , Figure 6 and Figure 7 , frame assembly 56 is movably secured to tower wall 46 via support assembly 75. Support assembly 75 includes support beams 76 and 80 that are immovable with respect to tower 18. Thus, support beams 76 and 80 transmit vibrations from tower wall 46 to vibration damper 22. Lower support beam 76 extends between and is secured to opposing flange pairs 82a, 82b and 84a, 84b attached to tower wall 46. As shown in FIG. Figure 4 As shown, the lower support beam 76 is spaced apart from the platform 40. In one embodiment, the vibration damper 22 may not rest directly on the platform 40. In another embodiment, the vibration damper 22 may be supported directly by the platform 40 and / or the platform 44, rather than being directly attached to the tower 18. Thus, the lower support beam 76 raises the mass 66, 74 in a direction toward the nacelle 24. The lower frame 62 is adjustably coupled to the lower support beam 76 at three locations, as described below. These positions allow the frame assembly 56 generally, and the lower frame 62 specifically, to move relative to the lower support beam 76.

[0056] At the other end of the frame assembly 56, i.e., at the upper frame 60, an upper support beam 80 is secured to the outer wall 46 by opposing flange pairs 86a, 86b and 90a, 90b. The upper support beam 80 extends between and is rigidly secured to the opposing flange pairs 86a, 86b and 90a, 90b, which are attached to the tower wall 46. The upper support beam 80 can support Figure 4 The platform 44 is shown. The upper frame 60 is movably coupled to the upper support beam 80 at three locations. These locations allow the frame assembly 56 generally and the upper frame 60 specifically to move relative to the upper support beam 80.

[0057] Advantageously, the central axis 64 of the vibration damper 22 is movable relative to the tower longitudinal axis 20. The longitudinal axis 20 of the tower 18 is rarely aligned completely vertically with respect to the earth's gravity when installed, and the tower 18 rarely remains in its installed position during the life of the wind turbine 10. That is, the orientation of the tower 18 may change over time. Embodiments of the present invention advantageously include a tilt mechanism 88 by which the central axis 64 of the vibration damper 22 can be moved relative to the longitudinal axis 20, such as during installation of the wind turbine 10 or after operation of the wind turbine 10. Thus, the vibration damper 22 can be redirected relative to the tower 18 when the wind turbine 10 is constructed or after an operating period. As an example, the tilt mechanism 88 is operable to redirect the central axis 64 in the direction of gravity and out of alignment with the longitudinal axis 20 of the tower 18 to compensate for movement of the tower 18 over time. With the central axis 64 aligned substantially parallel to gravity, the vibration damper 22 more effectively damps tower vibrations and reduces tower fatigue. The alignment of the central axis 64 with gravity also maximizes the symmetrical left-right displacement of the masses 66, 74 during oscillation, as described below. Although the exemplary embodiment of the tilt mechanism 88 is described with respect to the orientation of the tower 18, the tilt mechanism 88 is not limited to use with respect to the tower 18. For example, the vibration damper 22 can be installed in a tower section. The tower section can be erected and stored at the dockside to await loading onto a ship for transportation to the installation location. While at the dockside, the orientation of the tower section will likely be non-vertical due to gravity. The vibration damper 22 can be oriented in the section at the dockside with respect to gravity, and then redirected once the tower section is assembled with other sections to form the tower 18.

[0058] For this purpose, and with reference to Figure 6 , Figure 7 , Figure 8 , Fig. 9 , Fig.10 , Fig.11 , Fig. 12A , Fig. 12B and Fig. 12C The tilt mechanism 88 operably couples the frame assembly 56 to the support beams 76 and 80. In an exemplary embodiment, the tilt mechanism 88 includes a radial adjustment mechanism 104 and a lateral adjustment mechanism 106. Figures 9 to 11As shown, mechanisms 104 and 106 are located between support beam 76 and lower frame 62 and are coupled to both lower frame 62 and lower support beam 76. Exemplary mechanisms 104 and 106 include a pair of supports, one attached to each of frame 62 and beam 76. A threaded rod extends through both supports. Rotating the rod moves the supports further apart or closer together. Merely by way of example, mechanisms 104 and 106 may be ball screws or lead screws with end supports through which rotation of the threaded rod changes the distance between the end supports. In this manner, adjustment mechanisms 104 and 106 move frame assembly 56 individually or collectively relative to tower 18 and, in particular, relative to beams 76, 80.

[0059] Reference Figure 7 , Figure 8 , Fig. 9 , Fig.10 , Fig.11 and Fig. 12A , the radial adjustment mechanism 104 is configured to move the frame assembly 56 relative to the support beam 76 toward or away from the longitudinal axis 20 of the tower 18. In other words, the operating mechanism 104 pushes (or pulls) the lower frame 62 on the support beam 76 away from (or toward) the longitudinal axis 20. This is caused by Figure 8 , Fig. 9 and Fig.10 The arrow 124 in FIG. 1 shows that Fig. 12A The lateral mechanism 106 is configured to slide the frame assembly 56 in a direction parallel to the support beam 76. The operating mechanism 106 slides the frame assembly 56 laterally in a plane generally perpendicular to a radial plane including the longitudinal axis 20 of the tower 18. This movement is performed by Figure 8 , Fig. 9 , Fig.10 and Fig.11 As shown by arrow 126 in FIG. Fig. 12B and Fig. 12C Further description.

[0060] Through this general description, Figure 6 , Figure 7 , Fig. 9 and Fig.11 In the illustrated embodiment, the lower frame 62 is movably coupled to the lower support beam 76 at three load-bearing flanges, including a left flange 108, a center flange 110, and a right flange 112. Each flange 108, 110, and 112 is slotted and pivotally coupled to the lower frame 62 at a joint 116. Bolts couple the slotted flanges 108, 110, 112 to the beam 76. After the bolts are loosened, each of the slotted flanges 108, 110, 112 is capable of limited sliding movement relative to the lower support beam 76 in directions 124 and 126 via the slots.

[0061] In an exemplary embodiment, the lower support beam 76 defines a sliding surface 114 having three sliding planes 118, 120, and 122. Each of the inclined sliding planes 118 and 122 is angled with the middle sliding plane 120. For example, an obtuse angle is shown, wherein the exemplary angles between the planes 118 and 120 and between the planes 120 and 122 are 140° to 165°. The angles generally depend on the size of the damper 22, which may vary for different towers. In this regard, as a further example, the angles between the planes 118 and 120 and 122 and 120 are in a range greater than 0° but less than 180°. Alternatively, any two pairs of planes 118 and 120 and / or the planes 120 and 122 may be coplanar (i.e., at 180°) or oriented at 90° relative to each other. Although a symmetrical planar arrangement of the sliding planes 118, 120, and 122 relative to the central axis 64 is shown, other planar arrangements are possible, and embodiments of the present invention are not limited to the arrangements shown.

[0062] The tilt mechanism 88 may also include features at the upper frame 60. Figure 7 , slotted flanges 128 (left) and 132 (right) are pivotally coupled to the frame assembly 56 at joints 134. The left slotted flange 128 and the right slotted flange 132 are bolted to locations between the flange pairs 86a, 86b, 90a, 90b. The slotted flanges 128 and 132 pivot within a plane of the frame assembly 56 that is generally parallel to the center axis 64. The middle slotted flange 130 is pivotally coupled to the upper trident member 94 and can rotate in all directions. In an exemplary embodiment, the flange 130 defines an axis of rotation 105 about which the lower frame 62 can rotate. The middle flange 130 is bolted to the upper beam 80. The bolts on each flange 128, 130, and 132 are loosened prior to rotating the frame assembly 56, as described below with reference to the accompanying drawings. Fig. 12A , Fig. 12B and Fig. 12C described.

[0063] refer to Fig. 12A , Fig. 12B and Fig. 12C Movement according to mechanisms 104 and 106 is shown. The radial adjustment mechanism 104 is capable of rotating the central axis 64 clockwise or counterclockwise in a radial plane of the longitudinal axis 20. To produce the rotation, operation of the radial adjustment mechanism 104 causes the lower frame 62 on flanges 108, 110 and 112 to slide in a direction 124 toward or away from the longitudinal axis 20. This sliding movement causes the frame assembly 56 to rotate about an axis 105 defined at the upper frame 60. The movement associated with the radial adjustment mechanism 104 is Fig. 12A It is schematically shown in FIG.

[0064] like Fig. 12A As shown, in an orientation where the tower 18 is not vertically oriented with respect to the gravity 68, the longitudinal axis 20 of the tower 18 may form an angle β' with the direction of the gravity 68. In this figure, the non-vertical orientation of the tower 18 is exaggerated for illustrative purposes. Although not actually shown in the figure, β' may be substantially less than 2°. The central axis 64 of the vibration damper 22 may initially be at Fig. 12A The plane is parallel to the longitudinal axis 20, as shown in the figure. Fig. 12A The plane of is the radial plane in which the longitudinal axis 20 and the central axis 64 lie. The initial position of the vibration damper 22 is shown in dashed outline. The axis of rotation 105 projects to Fig. 12A , and is located at the upper frame 60 between the frame assembly 56 and the support beam 80. The center axis 64 is initially parallel to the longitudinal axis 20 and therefore forms an angle β' with the direction of gravity 68. With this initial arrangement, the radial adjustment mechanism 104 is adjusted to slide the lower frame 62 to the left (according to arrow 124) relative to the beam 76. This sliding movement rotates the center axis 64 marked "A" away from alignment with the longitudinal axis 20 (clockwise rotation is shown by arrow 124). The rotation allows the center axis 64 to be aligned parallel to gravity 68 at "B". Although not shown in the example, counterclockwise rotation is possible. The lateral adjustment mechanism 106 also produces rotation of the frame assembly 56.

[0065] In this regard and with reference Fig. 12B and Fig. 12C , the lateral mechanism 106 is shown rotating the central axis 64 into alignment with gravity 68. Fig. 12B , the central axis 64 of the vibration damper 22 may be aligned with the longitudinal axis 20 of the tower 18. As shown, the orientation of the tower 18 may shift over time such that neither the central axis 64 nor the longitudinal axis 20 are perpendicular. Fig. 12B In the plane of FIG. 6 , the axes 20, 64 may form an angle β′ with the direction of gravity 68. Note that the angle β′ ( Fig. 12A ) and β" may not be equal and are the angular orientations of the components of the direction of gravity 68 that reside in the plane of the corresponding drawing. Similarly, Fig. 12B and Fig. 12C In the figure, the non-vertical orientation of the tower 18 is exaggerated for illustrative purposes. Although not actually shown in the figure, β" can be substantially less than 2°.

[0066] With this initial arrangement, the lateral adjustment mechanism 106 is adjusted to slide the lower frame 62 to the right relative to the beam 76 (according to Fig. 12CThe sliding movement rotates the center axis 64 away from alignment with the longitudinal axis 20 (counterclockwise rotation is shown by arrow 126). The rotation allows the center axis 64 to be aligned parallel to the gravity 68, as shown in FIG. Fig. 12C Although not shown in the example, clockwise rotation is possible.

[0067] exist Fig. 12C 1, the central axis 64 rotates about an axis 107 that is generally perpendicular to the longitudinal axis 20. In conjunction with adjustment of the lateral mechanism 106, the relative orientation of the sliding planes 118, 120, and 122 and the slotted flanges 110, 112 produces rotation of the frame assembly 56. By way of example only, and with reference to the accompanying Fig.11 and Fig. 12C , the mechanism 106 is operated to move the lower frame 62 to the right (indicated by arrow 126) so that the left slotted flange 108 slides to a lower position on the left angled plane 118, while the right slotted flange 112 slides to a higher position on the right angled plane 122. The middle flange 110 slides along the middle plane 120. This sliding motion, guided by the planes 118, 120 and 120 relative to the flanges 108, 110 and 112, respectively, raises the lower frame 62 on the right side (at the flange 112) and lowers the frame 62 on the left side (at the flange 108) relative to the support beam 76. In this manner, the frame assembly 56 rotates about the axis 107 ( Fig. 12C ). In this example, the central axis 64 is rotated counterclockwise toward the orientation of the gravity 68. After the rotation, the central axis 64 may be aligned with the gravity 68. By way of example and not limitation, the rotation / tilt range of both the radial adjustment mechanism 104 and the lateral adjustment mechanism 106 is ±2°.

[0068] At the upper frame 60, adjustment of the lateral mechanism 106 causes the upper frame 60 to move in accordance with the movement of the lower frame 62. For example, if the lower frame 62 is tilted upward on the right side (e.g., Fig. 12C The upper frame 60 is also tilted upward on the right side. Fig. 12B and Fig. 12C This rotation may result in some relative sliding movement between the left and right slotted flanges 128, 130 and the support beam 80 at the upper frame 60. The middle flange 130 rotates to allow the upper frame 60 to Fig. 12C Rotational motion in the plane of .

[0069] As can be appreciated, the process for aligning the central axis 64 with the direction of gravity 68 may require iteration between adjustments of the radial adjustment mechanism 104 and the lateral mechanism 106 to solve for the angles β′ and β″. The angles β′ and β″ may be components of the angle β (see Fig. 22 ).

[0070] Reference now Fig.13 and Fig.14 In an exemplary embodiment, each of the upper mass 66 and the lower mass 74 is assembled from a plurality of plates 136. The plates 136 include a main upper plate 140 for the upper mass 66 and a main lower plate 142 for the lower mass 74. Additional individual plates 136 may then be coupled to the main upper plate 140 and / or the main lower plate 142. The masses 66 and 74 may thus be tuned to the frequencies required for damping the wind turbine 10. In this regard, the individual plates 136 are selected and attached to the main plates 140, 142 to bring the total mass within a predetermined range for the wind turbine 10. As shown, the individual plates 136 may vary in thickness and / or outer dimensions, but may be stacked on and coupled to the main upper plate 140 or the main lower plate 142. The individual plates 136 determine the location of the center of mass 66a of the upper mass 66 and the center of mass 74a of the lower mass 74 (e.g., Figure 5 As shown in FIG. 1 , the position of the center of mass 66 a, 74 a of the mass blocks 66, 74 may also be modified.

[0071] In addition, masses 66 and 74 define a center of gravity 150 ( Figure 5 ).like Figure 5 As shown, since in the exemplary embodiment, the upper mass 66 is larger and heavier, the center of gravity 150 is shown in the upper mass 66. The center of gravity 150 can be moved by adding / removing plates 136 and / or changing their positions. The center of gravity 150 can be on the central axis 64.

[0072] The individual plates 136 can each have a shape and / or size that contributes to the bean-shape of the upper mass 66 or the lower mass 74. In an exemplary embodiment, the plates 136 define the bean-shape of the upper mass 66 and the lower mass 74 described above. Although the masses 66 and 74 are shown as an assembly of individual plates 136, embodiments of the present invention are not limited to an assembly of masses that form the bob portion of a pendulum. In particular, either or both of the masses 66 and 74 can be a single body. By way of example and not limitation, when the vibration damper 22 is positioned with its center of gravity 150 within 20 m of the flange 38 (e.g., Figure 2 As shown), the total mass of mass blocks 66 and 74 can be less than 39 metric tons, less than 28 metric tons, or less than 14 metric tons. As a further example, the upper mass block 66 can be 8,000 kg to 15,000 kg, and the lower mass block 74 can be 4,000 kg to 9,000 kg.

[0073] As mentioned above, and continue to refer to Fig.13 and Fig.14Each of the upper mass 66 and the lower mass 74 is movably coupled to the frame assembly 56 by a pendulum rod 70 and a universal joint 72. The upper mass 66 and the corresponding rod 70 and the universal joint 72 form a suspended pendulum 144, and the lower mass 74 and the corresponding rod 70 and the universal joint 72 form an upright pendulum 146. The pendulums 144, 146 are Figure 6 is marked.

[0074] The pendulums 144, 146 each swing along an arcuate path defined by the rod 70 and the universal joint 72. In an exemplary embodiment, although these paths are spaced apart and separated, the pendulums 144, 146 are coupled together so that the motion of the two pendulums 144 and 146 is synchronized in the left-right motion. That is, the pendulums 144, 146 each follow their independent arc paths, but their relative horizontal positions to equilibrium are the same. However, their relative vertical positions change. Therefore, during oscillation, the upper mass 66 and lower mass 74 of the pendulums 144 and 146, respectively, trace paths where their horizontal positions to equilibrium are the same but their separation in the vertical direction increases. The vertical component of the arc traced by the upper mass 66 is positive in the sense that the upper mass 66 swings in the upward direction as it is displaced from the equilibrium horizontal. The lower mass 74 traces an equal but negative vertical position because it swings in the downward direction as it is displaced from equilibrium along the same horizontal path as the upper mass 66. By swinging the pendulum 144 upward and the upright pendulum 146 downward, the separation of the masses 66, 74 increases with the horizontal displacement. This is shown by comparing Fig.13A and Fig. 13B Shown schematically.

[0075] With the coordinated arc paths of pendulums 144, 146, the gap between masses 66 and 74 expands from a minimum distance between masses 66, 74 at equilibrium (i.e., gap 78) to a maximum value when masses 66, 74 are at maximum horizontal displacement from equilibrium. With maximum vertical and horizontal displacements, during oscillation, pendulums 144, 146 track Fig.15A When viewed along a plane cut through the maximum horizontal displacement, the masses 66 and / or 74 track Fig. 15B 144, 146 in all directions and may correspond to the maximum damping capacity of the vibration damper 22 on the tower 18. In the illustrated embodiment, the active volume 152 has a partial annular configuration that generally fills the annular space between the longitudinal axis 20 and the outer wall 46. The active volume 152 does not intersect the longitudinal axis 20, and therefore the vibration damper 22 does not enter the space between the openings 50, 52 ( Figure 2 ). Fig. 15B. The maximum displacement indicated by the perimeter 158 is between the tower wall 46 and the longitudinal axis 20, and more specifically, between the tower wall 46 and the opening 50. The annular arcuate perimeter 158 includes an arc 168 along the radial centerline of the perimeter. The centerline is half the distance between the outer arc and the inner arc of the perimeter 158, and extends from the rounded end 165 to the rounded end 167. The radius of the arc 168 can be equal to or less than half the radius of the tower wall 46 at the height of the annular arcuate perimeter 158. The annular arcuate perimeter has an arc amount less than 180°.

[0076] For this purpose, and with reference to Fig.14 , pendulums 144 and 146 are coupled together to allow mass blocks 66, 74 to separate vertically in the direction of central axis 64, but to minimize or eliminate changes in relative horizontal movement of mass blocks 66, 74 during their oscillations. In an exemplary embodiment, pendulums 144 and 146 are coupled together at three locations, but embodiments are not limited to three locations. More or fewer connections between pendulums 144 and 146 can be envisioned.

[0077] like Fig.14 and Fig.16 As shown, the coupling mechanism 154 provides a sliding vertically oriented connection between the pendulum 144 and the inverted pendulum 146. In particular, the coupling mechanism 154 movably connects the upper mass 66 to the lower mass 74 and defines a vertical axis of motion 156 by which the gap 78 can be increased and decreased, but by which relative left-right displacement of the masses 66 and 74 is prohibited. In an exemplary embodiment, the vertical axis of motion 156 and the central axis 64 coincide with the center of gravity 150 residing on the vertical axis of motion 156, while the masses 66, 74 are in balance. The coupling mechanism 154 prevents, for example, the pendulum 144 from swinging in one direction, and simultaneously prevents the inverted pendulum 146 from swinging in the opposite direction.

[0078] In the illustrated embodiment, the coupling mechanism 154 includes a guide beam 160 fixed to the lower mass 74 on the main plate 142. On the upper mass 66, a guide assembly 162 is suspended from the upper main plate 140. The guide assembly 162 may include a depending tube that defines an opening at one end thereof that is configured to receive the guide beam 160 in, for example, a telescopic manner. The tube may include one or more low-friction contact pads along the inner surface of the tube to define the opening. The contact pads facilitate movement of the guide beam 160 and the guide assembly 162 relative to each other. The through hole 164 ( Fig.14) together with an opening in a guide assembly 162 receives a guide beam 160 in the direction of the central axis 64. With the guide assembly 162 engaged with the guide beam 160, the movement of the upper mass 66 relative to the lower mass 74 is constrained to move along the vertical motion axis 156. That is, the masses 66 and 74 can separate from and approach each other vertically along the axis 156, but cannot be displaced left-right (i.e., perpendicular to the axis 156) relative to each other. With this configuration, during oscillation, the masses 66 and 74 are constrained to the same left-right position, but can be separated from each other along the vertical motion axis 156.

[0079] In an exemplary embodiment, the pendulums 144, 146 interact at two additional locations spaced apart from the coupling mechanism 154. Fig.14 , Fig.16 and Fig.17 In the embodiment of the present invention, a pair of end stops 170 extend between the pendulum 144 and the inverted pendulum 146. The stop 170 is coupled to the pendulum 144 or the pendulum 146. In an exemplary embodiment, the stop 170 is coupled to the pendulum 144. In an exemplary embodiment, each end stop 170 is configured to limit the maximum displacement of the pendulums 144 and 146, and thus can at least partially define the active volume 152 (see Fig.15A ).

[0080] To this end, the end stop 170 limits the vertical separation between the upper mass 66 and the lower mass 74 along the vertical axis of motion 156. That is, the end stop 170 determines a predetermined maximum gap between the masses 66, 74 during oscillation of the pendulums 144 and 146. When the pendulums 144 and 146 are in their equilibrium positions, the predetermined maximum gap is greater than the gap 78. However, if the pendulums 144 and 146 are not restricted (e.g., without the end stop 170) and are therefore allowed to swing to the maximum amplitude allowed by the rod 70 and the universal joint 72, the predetermined maximum gap may be less than the vertical separation distance between the upper mass 66 and the lower mass 74 along the axis 156. At the predetermined maximum gap, the end stop 170 prevents the masses 66, 74 from moving further away from each other along the vertical axis of motion 156. Due to the restriction of movement on the vertical axis of motion 156, the end stop 170 also limits the left-right displacement of the masses 66, 74 from equilibrium. End stops 170 may prevent masses 66 and 74 from reaching their maximum amplitude as defined by the maximum arc that rod 70 and gimbal 72 may trace.

[0081] In addition to limiting the maximum vertical separation between the upper mass 66 and the lower mass 74, the end stop 170 also reduces the velocity of the masses 66 and 74 during oscillation. As the pendulums 144 and 146 oscillate, the masses 66 and 74 move horizontally and vertically along their respective arcs. Along these arcs, the end stop 170 is engaged to slow the vertical separation rate of the masses 66, 74 when approaching a predetermined maximum gap. And, at the predetermined maximum gap, the end stop 170 slows the impact of the masses 66, 74. In each aspect, the end stop 170 absorbs and dissipates the kinetic energy of the masses 66, 74 along at least a portion of the arc path of the masses 66, 74. Advantageously, this reduces mechanical fatigue on the vibration damper 22 and the tower 18.

[0082] refer to Fig.14 , Fig.16 and Fig.17 In an exemplary embodiment, the end stop 170 is carried by the upper mass 66. Fig.14 As shown, the end stop 170 is received in a through hole 172 in the plate 136 of the upper mass 66 and in a blind hole 174 in one or more plates 136 in the lower mass 74. The end stop 170 is a tubular body in which a housing 176 slidably receives a guide sleeve 178 along a stop axis 180. When the end stop 170 is activated during the oscillation of the pendulums 144 and 146, the housing 176 and the guide sleeve 178 slide relative to each other in an interlocking manner along the axis 180. The axis 180 is generally parallel to the vertical axis of motion 156 of the masses 66, 74. Along the axis 180, an end cap 182 on the housing 176 is opposite to an end cap 184 of the guide sleeve 178. The end caps 182, 184, the housing 176 and the guide sleeve 178 define an operating volume of the end stop 170. When the end stop 170 is activated during oscillation, the distance between the end caps 182 and 184 and therefore the operating volume of the end stop 170 changes.

[0083] In this regard, the housing 176 is secured to the upper mass 66 at a flange 186 on the top surface of the upper mass 66 proximate a seal 188 between the housing 176 and the guide sleeve 178. As shown, the end cap 182 of the housing 176 is located in the blind hole 174 in the lower mass 74. The end cap 182 may not contact the lower mass 74 in the blind hole 174. The end cap 184 of the guide sleeve 178 is coupled to an opposing yoke or crossbar 192 by a pair of tie rods 194 by a yoke or crossbar 190. As shown, the tie rods 194 extend through each of the masses 66 and 74, wherein the opposing crossbar 192 is positioned near the lower surface of the lower mass 74. The lower mass 74 moves relative to the opposing crossbar 192 so that the lower surface of the lower mass 74 can contact the crossbar 192 during oscillation. The contact at the crossbar 192 activates the end stop 170. This occurs when the upper mass 66 and the lower mass 74 separate vertically. When activated, the end caps 182 and 184 move toward each other along the axis 180 and the operating volume is reduced.

[0084] refer to Fig.16 and Fig.17 , within the operating volume, particularly within the housing 176, there is a gap 198 between the guide sleeve 178 and the end cap 182. When the end stop 170 engages during the oscillation of the pendulums 144 and 146, the gap 198 narrows. The exemplary end stop 170 houses a piston 196 that extends from the end cap 182 and is partially housed in a piston sleeve 200 that extends from an opposing end cap 184. There is a gap 206 between the end of the piston 196 and the end cap 184. Similar to the gap 198, the gap 206 narrows when the end stop 170 engages during the oscillation. A coil spring 202 is housed between the piston 196 and the piston sleeve 200 and may be attached to the end cap 184. A bumper 204 surrounds the piston 196 at the end cap 182 and is positioned to engage the spring 202. The bumper 204 may be a layered stack of an elastomeric material such as rubber. As shown, spring 202 and bumper 204 together extend the entire height of the operating volume from end cap 182 to end cap 184. In an unactivated state, as shown, neither spring 202 nor bumper 204 is compressed. Damping fluid 210 fills a portion of the operating volume. Fluid 210 is typically a high viscosity fluid.

[0085] During the oscillation of pendulums 144 and 146, as masses 66 and 74 move along their arcuate paths, the vertical separation between them increases. The vertical separation is along a vertical motion axis 156 according to coupling mechanism 154. The initial separation of masses 66 and 74 from the equilibrium position may not activate end stop 170. That is, there may be a portion of the pendulum motion that does not contact end stop 170. Fig.17The end stop 170 shown in FIG. 1 has no mechanical engagement, and in particular, the lower mass 74 does not contact the crossbar 192 .

[0086] Once the vertical separation reaches a predetermined distance, the lower mass 74 contacts the crossbar 192 at 212. Fig.17 In the illustrated embodiment, the mass 74 contacts the crossbar 192 at the spacer 214. It should be noted that the distance between the spacer 214 and the lower surface of the mass 74 can be adjusted with a screw 216. Reducing the distance between the spacer 214 and the lower mass 74 causes the end stop 170 to be activated more quickly in the oscillation of the pendulums 144 and 146 (i.e., at smaller left-right displacements of the masses 66 and 74 and at smaller deviations from the gap 78 at equilibrium). Adjustment can include activating the end stop 170 at equilibrium. Thus, a full range of adjustment can be from inactive at equilibrium to active at equilibrium (i.e., the coil spring is always at least partially compressed). In addition, the spacer 214 can be removed during operation in the tower 18, but it can be used to tune the vibration damper 22 for use with the tower section when the tower section is at dockside or on a ship.

[0087] Adjustment of the end stop 170 is advantageous because the vibration damper 22 can be tuned to the structure and / or surrounding vibration environment in which it is installed. For example, when the vibration damper 22 is installed in a structure such as section 18c ( Figure 1 ), before the vibration damper 22 is assembled with the other sections 18a, 18b, the vibration damper 22 can be tuned to absorb vibrations of section 18c only. Such vibrations can be significantly different from the vibrations of the tower 18. Before the section 18c is installed, the section 18c can be located at the quayside. In this environment, the end stop 170 can be adjusted to damp the vibrations of the tower section 18c while at the quayside. Once the section 18c is loaded onto the ship, the end stop 170 can be adjusted again to damp the vibrations of the tower section 18c on the ship. Thus, the end stop 170 can be tuned to the specific frequency response desired for the structure and / or location at each stage from the manufacture of the tower section to the installation of the tower section (e.g., at an offshore location and then during operation of the wind turbine).

[0088] During oscillation, after the lower mass 74 contacts the spacer 214, the end stop 170 is activated. As the masses 66 and 74 further separate, i.e., when the vertical separation between the upper mass 66 and the lower mass 74 is Fig.17As the pressure increases in the direction of arrow 220 in FIG. 1 , the housing 176 and the guide sleeve 178 slide relative to each other, and each of the gaps 198 and 206 decreases. As the distance between the end caps 182 and 184 decreases, the coil spring 202 is compressed. In this way, the force of the coil spring 202 resists further separation of the masses 66, 74. As the end caps 182 and 184 approach each other and the operating volume decreases, the fluid 210 also resists further separation.

[0089] With additional separation of the masses 66 and 74 along the vertical motion axis 156, the coil spring 202 may become fully compressed along the axis 180 and the buffer 204 may be engaged. In this configuration, the fully compressed coil spring 202 and the buffer 204 mechanically couple each of the end caps 182 and 184, thereby forming a column of material that is more rigid than the uncompressed coil spring 202. The buffer 204 and the column of fully compressed springs 202 may only be elastically compressed, as determined by the buffer 204. This limits further vertical separation of the masses 66, 74, wherein the only remaining mechanical elasticity in the end stop 170 is the elasticity of the buffer 204. The buffer 204 is configured to absorb kinetic energy to stop the masses 66 and 74 when they reach a predetermined maximum clearance allowed by the end stop 170. Fig. 20 The performance of a vibration damper 22 with an exemplary end stop according to an embodiment of the present invention is depicted. From the graph, it is believed that the exemplary embodiment of the end stop has improved damping at larger accelerations of the tower. For example, at "a_th" of the "DAMPER WITH END STOP", the end stop is activated, wherein the spring is compressed and the damping fluid is displaced. By comparing the "DAMPERWITH END STOP" graph with the "DAMPER WITHOUT END STOP" graph, it is noted that the former provides greater damping levels than the latter at almost all acceleration levels of the tower. Higher damping at all levels indicates improved damping performance.

[0090] According to one aspect of the present invention, as with any complex machine, maintenance and / or repair is sometimes required. For safety purposes, the vibration damper 22 must be stationary or nearly stationary despite ongoing tower vibrations during maintenance and / or repair of the vibration damper 22 or other equipment near the vibration damper 22. To this end, reference is now made to Figure 2 , Fig.19 , Fig. 20 , Fig.21A and Fig. 21BIn an exemplary embodiment, the locking mechanism 222 is operable to limit or inhibit oscillation of the vibration damper 22. Generally, the locking mechanism 222 is movable relative to the masses 66, 74 in a direction parallel to the vertical axis of motion 156 between an unlocked position for normal operation of the vibration damper 22 and a locked position for maintenance / repair. In the locked position, the locking mechanism 222 limits or inhibits separation of the masses 66 and 74 in the vertical direction. By limiting / inhibiting vertical separation, the locking mechanism 222 also reduces or dampens the side-to-side oscillation of the pendulums 144, 146.

[0091] In an exemplary embodiment, the actuator rod 224 is moved from the active volume 152 ( Fig.15A and Fig. 15B ), such as from platform 44 on a level above vibration damper 22. Service personnel may reach through an entrance (not shown) in platform 44 to activate locking mechanism 222 by rotating rod 224 as pendulums 144 and 146 oscillate. Rod 224 is rotatably coupled by cap 226 to a threaded shaft 228 received in guide beam 160 of coupling mechanism 154.

[0092] As referenced above Fig.14 , Fig. 20 and Fig.21A As shown and described, the guide beam 160 (and cap 226) are fixed to the main lower plate 142 of the lower mass 74. The threaded shaft 228 is held in a fixed rotatable position about the guide beam 160 by the cap 230 at the lower end of the guide tube 232. The guide tube 232 is fixed to the upper mass 66 by the bracket 234. The guide tube 232 slidably receives the stop element 236 on the threaded shaft 228. Fig. 21C In one embodiment, the stop element 236 has a tubular body with opposing guide pins 250 that extend outwardly to be received in corresponding slots 252 of the guide tube 232.

[0093] refer to Fig.21A , rotating the actuating rod 224 rotates the threaded shaft 228 and raises the stop element 236 from the unlocked position toward the locked position. The cap 226 is fixed to the lower mass 74 via the guide beam 160, and the stop element 236 is fixed to the upper mass 66 via the guide tube 232 and the bracket 234. Fig.21A Raising the stop element 236 (attached to the upper mass 66) sufficiently close to the cap 226 (attached to the lower mass 74) reduces the available vertical movement of the masses 66, 74 along the vertical axis of motion 156, as shown by the vertical arrow 238 in FIG. Fig. 21C In the embodiment shown in FIG. 2 , the pin 250 slides as the stop element 236 moves relative to the guide tube 232 in the slot 252 between the locked position and the unlocked position.

[0094] like Fig. 21B As shown, the locked position is reached when the stop element 236 abuts the cap 226. The vertical separation of the upper mass 66 and the lower mass 74 is significantly reduced in the locked position. In the absence of available vertical space, horizontal movement away from the equilibrium position is significantly reduced to a threshold level that is safe for maintenance personnel to approach the vibration damper 22. In the locked position, the horizontal movement of the masses 66 and 74 is limited to less than ±120 mm from equilibrium.

[0095] To substantially eliminate any residual movement of the pendulums 144 and 146 after the locking mechanism 222 is engaged, maintenance personnel may attach and tension a soft link (e.g., Figure 6 The chain 240 in the cap 230 or similar to the lower mass 74 is used to prevent any residual movement of the masses 66 and 74 and to support the locking mechanism 222 against tower vibration while maintenance personnel complete maintenance and / or repairs. The process is reversed by removing the soft link 240 and moving the stop element 236 away from the cap 230, which moves the locking mechanism 222 from the locked position ( Fig. 21B ) moves to the unlock position ( Fig.21A ), in which unlocked position the pendulums 144 and 146 oscillate freely.

[0096] refer to Fig. 22 , showing Figure 1 A mathematical model of the wind turbine 10 is provided. In the model, m is the generalized mass of the wind turbine 10, k is the generalized stiffness of the wind turbine 10, d is the generalized damping coefficient of the wind turbine 10, F is the modal excitation force, g is the acceleration due to gravity, β is the angle of the effective gravity direction (g) and includes the static tilt and dynamic tilt of the tower 18, q is the displacement of the wind turbine 10, IP is the pendulum length of the pendulum rod 70, m1 is the mass of the upper mass block 66, m2 is the mass of the lower mass block 74, and q rel is the relative displacement of the upper mass block 66 and the lower mass block 74 from equilibrium, and z is the relative displacement of the upper mass block 66 and the lower mass block 74 at q rel The vertical displacement at k t is the adjustment of the coil spring 202 of the end stop 170, k c is the horizontal stiffness of the connecting mechanism 154, k end is the vertical stiffness and damping of the end stop 170, d1 is the generalized damping coefficient of the linear damper, and d2 is the generalized damping coefficient of the linear damper. In this model, nonlinear effects due to large deflections of the tower 18 and masses 66, 74 hitting the end stop 170 are taken into account.

[0097] Although the present invention has been illustrated by the description of various preferred embodiments, and although these embodiments have been described in some detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to these details. Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the various features of the present invention may be used alone or in any combination, depending on the needs and preferences of the user.

Claims

1. A tubular structure for forming at least a portion of a wind turbine tower (18) of a wind turbine (10), the tubular structure comprising: an elongated tubular body having a first end, a second end, and a tower wall (46) extending between the first end and the second end, wherein the first end is configured to be connected to a nacelle (24) of the wind turbine (10), and wherein the tower wall (46) defines a longitudinal axis (20) of the tubular body; a vibration damper (22) having a central axis (64) and coupled to the tubular body; and A tilt mechanism (88) is operably coupled to the vibration damper (22) and is configured to change the orientation of the central axis (64) of the vibration damper (22) relative to the longitudinal axis (20) of the tubular body.

2. The tubular structure according to claim 1, wherein: The tilt mechanism (88) includes a lateral adjustment mechanism (106) configured to rotate the vibration damper (22) about an axis (107) perpendicular to the longitudinal axis (20).

3. A tubular structure according to claim 1 or claim 2, wherein: The longitudinal axis (20) defines a radial plane that intersects the vibration damper (22), and wherein the tilting mechanism (88) includes a radial adjustment mechanism (104) configured to rotate the vibration damper (22) about an axis (105) perpendicular to the radial plane.

4. A tubular structure according to any preceding claim, wherein: A support assembly (57) is rigidly connected to the tubular structure, and wherein the vibration damper (22) further comprises: A frame assembly (56) is slidably supported on the support assembly (57), wherein the tilt mechanism (88) is operably connected to the frame assembly (56) and the support assembly (57), whereby operation of the tilt mechanism (88) causes the frame assembly (56) to move relative to the support assembly (57).

5. The tubular structure according to claim 4, wherein: The frame assembly (56) is pivotally secured to the support assembly (57).

6. The tubular structure according to claim 5, wherein: The frame assembly (56) is pivotable within a plane in which the tilt mechanism (88) changes the orientation of the central axis (64).

7. A tubular structure according to any one of claims 4 to 6, wherein: The tilt mechanism (88) is located between the frame assembly (56) and the support assembly (57).

8. A tubular structure according to any one of claims 4 to 7, wherein: The support assembly (57) defines a sliding surface, and the frame assembly (56) is slidably supported on the sliding surface, and the sliding surface (114) includes an inner sliding plane (120) perpendicular to the longitudinal axis (20) and a first outer sliding plane (118) and a second outer sliding plane (122) on opposite sides of the inner sliding plane (120), each of the outer sliding planes (118, 122) forming an obtuse angle with respect to the inner sliding plane (120), and wherein the slotted flange (108, 110, 112) is pivotally fixed to the frame assembly (56) and is slidably engaged with each of the inner sliding plane and the outer sliding plane (118, 120, 122).

9. A tubular structure according to any one of claims 4 to 8, wherein: The tilting mechanism (88) comprises: a pair of supports, one of which is coupled to the frame assembly (56) and the other of which is coupled to the support assembly (57), and A threaded rod rotatably couples the pair of supports together, whereby rotation of the threaded rod changes the distance between the pair of supports.

10. A wind turbine (10) comprising a tubular structure according to any preceding claim.

11. A method of damping vibrations in a tubular structure, the tubular structure being configured to form at least a portion of a wind turbine tower (18) of a wind turbine (10), the tubular structure having an elongated tubular body having a first end, a second end, and a tower wall (46) extending between the first end and the second end, the tower wall (46) defining a longitudinal axis (20) of the tubular body, the vibration damper (22) having a central axis (64) and connected to the tubular structure adjacent the first end, the method comprising: erecting the tubular structure so as to be supported at the second end of the tubular body, the longitudinal axis (20) of the erected tubular body having a first orientation; as well as The vibration damper (22) is adjusted relative to the tower wall (46) such that the central axis (64) of the vibration damper (22) has a second orientation relative to the longitudinal axis (20) of the tubular body that is different from the first orientation.

12. The method according to claim 11, wherein: Adjusting the vibration damper (22) further comprises: determining an orientation of the longitudinal axis (20) of the tubular body relative to gravity (68); and The central axis (64) of the vibration damper (22) is rotated toward the orientation of the gravity force (68).

13. The method according to claim 12, wherein: Rotating the central axis (64) of the vibration damper (22) further comprises rotating the central axis (64) of the vibration damper (22) about an axis (107) that is perpendicular to the longitudinal axis (20).

14. The method according to claim 12 or claim 13, wherein: The longitudinal axis (20) defines a radial plane that intersects the vibration damper (22), and wherein rotating the central axis (64) of the vibration damper (22) further comprises rotating the vibration damper (22) about an axis (105) perpendicular to the radial plane.

15. The method according to any one of claims 12 to 14, wherein: The tubular body includes a support assembly (57), and the vibration damper (22) includes a frame assembly (56), the frame assembly (56) being slidably supported on the support assembly (57), and wherein rotating the central axis (64) of the vibration damper (22) also includes sliding the frame assembly (56) relative to the support assembly (57).

16. The method according to claim 15, wherein: During operation of the vibration damper (22) and prior to rotating the central axis (64) of the vibration damper (22), a plurality of fasteners connect the frame assembly (56) to the support assembly (57), the method further comprising: loosening the plurality of fasteners; and After sliding the frame assembly (56) relative to the support assembly (57), the plurality of fasteners are tightened.

17. The method according to claim 15 or claim 16, wherein: A tilt mechanism (88) is operable between the support assembly (57) and the frame assembly (56), and wherein rotating the central axis (64) of the vibration damper (22) further comprises operating the tilt mechanism (88).

18. The method according to claim 17, wherein: The tilting mechanism (88) comprises: a pair of supports, wherein one of the supports is coupled to the frame assembly (56) and the other of the supports is coupled to the support assembly (57); and a threaded rod rotatably coupled to the pair of supports, and Wherein, sliding the frame assembly (56) relative to the support assembly (57) further comprises rotating the threaded rod to change the distance between the pair of support members.

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