Wind turbine alignment tools

Abstract

A tool (600; 600') for aligning a tubular structure of a wind turbine comprises: a support member for attaching the tool (600; 600') to an end region of a first tubular structure (200) so as to extend axially outwardly from the end region; and a guide member connected to the support member by a biasing member and adapted to engage an inner wall (301a) of a second tubular structure (301), wherein the biasing member is arranged to push the guide member to exert a radial force on the inner wall (301a) when the second tubular structure (301) moves axially towards the first tubular structure (200), thereby guiding the second tubular structure (301) into axial alignment with the first tubular structure (200).

Description

Technical Field

[0001] The present invention relates to a tool for aligning a tubular structure of a wind turbine, such as an offshore or onshore wind turbine. Background Art

[0002] A typical wind turbine consists of a tubular tower, a nacelle located on the tower and containing a generator connected to a drive hub via a shaft, and rotor blades attached to the drive hub. During on-site installation of a wind turbine, the tower is assembled and the nacelle is attached to the top of the tower, typically using a flange-to-flange connection secured with bolts. For a proper connection, the flanges need to be centrally aligned so that they are facing each other and further rotationally aligned so that the bolt holes of the flanges match.

[0003] A tower may consist of several segments that are placed one on top of the other to construct the tower. Each of these segments is a large and heavy structure, and so is the nacelle. Consequently, large cranes or other lifting equipment are required to lift the tower segments and nacelle. These operations are made more difficult because they are often performed under non-ideal conditions, such as at sea or on uneven terrain.

[0004] In particular, the structure is susceptible to disturbances from wind loads during its installation. In the case of offshore wind turbines, the tower is additionally subjected to forces from waves. Consequently, when the nacelle is lowered toward the tower by a crane for attachment, the nacelle and tower can move laterally relative to each other. Similarly, the upper and lower tower sections can move laterally relative to each other during tower construction. This lateral movement makes it difficult to centrally align the structures to achieve the required flange-to-flange connection. The present invention aims to alleviate this problem, at least to some extent. Summary of the Invention

[0005] According to one aspect of the present invention, a tool for aligning tubular structures of a wind turbine is provided, comprising: a support member for attaching the tool to an end region of a first tubular structure so as to extend axially outwardly therefrom; and a guide member connected to the support member by a biasing member and adapted to engage an inner wall of a second tubular structure, wherein the biasing member is arranged to push the guide member to exert a radial force on the inner wall when the second tubular structure moves axially toward the first tubular structure, thereby guiding the second tubular structure into axial alignment with the first tubular structure.

[0006] The biasing member functions to counteract side wind forces acting on a second tubular structure of a wind turbine (e.g., a nacelle or a tower segment) to axially align the second tubular structure with a first tubular structure (e.g., a tower or another tower segment). In other words, the biasing member is arranged to urge the second tubular structure into axial alignment with the first tubular structure. In other words, the biasing member provides a restoring force to center the second tubular structure relative to the first tubular structure.

[0007] In addition to the centering effect, the biasing member tends to damp lateral oscillations or vibrations of the second tubular structure caused by crosswinds. Due to the damping, the impact of any contact between the second tubular structure and the first tubular structure when the second tubular structure is positioned on the first tubular structure is reduced or eliminated.

[0008] Thus, the alignment tool provides for the second tubular structure to be gradually guided into axial alignment with the first tubular structure as the second tubular structure is moved axially towards the first tubular structure while providing for damping of oscillations or vibrations of the first and second tubular structures caused by crosswinds.

[0009] As used herein with respect to the relationship between the guide member, support member and biasing member, “connected” is interchangeable with “linked.” Connecting or linking the guide member to the support member via the biasing member may involve all or only a portion of the biasing member.

[0010] The biasing member may comprise a resilient element, preferably a spring, more preferably a coil spring.

[0011] The biasing member may comprise a hydraulic element, preferably a hydraulic cylinder.

[0012] The guide member may be adapted to be positioned radially outwardly of the support member relative to the longitudinal axis of the first tubular structure; and the biasing member may be arranged to urge the guide member to exert an outward radial force on said inner wall.

[0013] At least a portion of the biasing member may be located between the support member and the guide member.

[0014] The support component may comprise a plurality of support members configured for attachment to the end region of the first tubular structure so as to be spaced, preferably equidistantly spaced, around the end region of the first tubular structure.

[0015] Each of the support members may include: an attachment portion, which is used to attach to the end region of the first tubular structure so as to extend substantially perpendicularly relative to the longitudinal axis of the first tubular structure; a first upright portion, which extends substantially perpendicularly from the attachment portion and is used to be positioned at an outer radial position relative to the longitudinal axis of the first tubular structure; a second upright portion, which is laterally offset from the first upright portion and is used to be positioned at an inner radial position relative to the longitudinal axis of the first tubular structure; and an inclined portion, which connects the first upright portion and the second upright portion.

[0016] The attachment portion and the first upright portion of each of the support members can be configured such that when the support member is attached to the end region of the first tubular structure, the distance between the opposing pairs of upright portions of the support member will be substantially the same as the inner diameter of the second tubular structure, such as to provide a sliding fit between the upright portions and the inner wall of the second tubular structure.

[0017] The guide component may include a plurality of guide members, and the biasing component may include a plurality of biasing elements, each of the guide members being connected to the second upright portion of a respective one of the support members by a respective one of the biasing elements.

[0018] Each of the guide members may include an upright portion for positioning in a substantially parallel relationship with the second upright portion of a corresponding one of the support members, and an inclined portion extending from the upright portion and preferably for positioning in a substantially parallel relationship with the inclined portion of the corresponding one of the support members.

[0019] The tool may comprise a connector part connecting the inclined portions of the guide members together.Preferably, the connector part comprises a generally conical shape.

[0020] Each of the biasing elements may include a coil spring having a first end attached to the second upright portion of a corresponding one of the support members and a second end attached to the upright portion of a corresponding one of the guide members such that the axis of the spring is substantially perpendicular to the upright portion.

[0021] Each of the biasing elements may comprise a hydraulic cylinder, each of the hydraulic cylinders being arranged in fluid communication with another of the hydraulic cylinders.

[0022] The body of each of the hydraulic cylinders can be attached to the second upright portion of a corresponding one of the support members; and the rod of the piston of the hydraulic cylinder can be movable relative to the body and can be attached to the upright portion of a corresponding one of the guide members so that the axis of the hydraulic cylinder is substantially perpendicular to the upright portion.

[0023] When the tool is attached to said end region, the entire tool may be contained within a protrusion of the edge of the end region of the first tubular structure.

[0024] According to another aspect of the present invention, there is provided a wind turbine generator at least partially installed and comprising a tool as described above.

[0025] According to another aspect of the present invention, a method for installing a wind turbine generator is provided, which comprises: attaching a support component of an alignment tool to an end region of a first tubular structure of the wind turbine generator so as to extend axially outward from the first tubular structure, the alignment tool comprising a guide component connected to the support component by a biasing component and adapted to engage an inner wall of a second tubular structure of the wind turbine generator; and axially moving the second tubular structure toward the first tubular structure so as to engage the inner wall with the guide component of the alignment tool, thereby enabling the biasing component to push the guide component to exert a radial force on the inner wall so as to guide the second tubular structure to be substantially axially aligned with the first tubular structure.

[0026] The biasing component of the alignment tool may include a plurality of hydraulic cylinders, each of the hydraulic cylinders being arranged to be fluidically connected to another of the hydraulic cylinders; and the method may include controlling the hydraulic cylinders to push the guide component to exert a constant said radial force on the inner wall so as to guide the second tubular structure substantially into axial alignment with the first tubular structure.

[0027] According to another aspect of the present invention, there is provided the use of a tool as described above in the above method. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Embodiments will now be described by way of example with reference to the accompanying drawings, in which:

[0029] Figure 1 A wind turbine comprising a nacelle mounted on a tower is shown;

[0030] Figures 2 to 4 An alignment tool according to a first example of the invention is shown, the tool being attached to a tower for aligning a nacelle with the tower;

[0031] Figure 5 An alignment tool according to a second example of the present invention is shown; and

[0032] Figure 6 Shown Figure 5 A variant of the alignment tool. DETAILED DESCRIPTION

[0033] Reference Figure 1, the exemplary offshore wind turbine 100 includes a tower 200 (having a mass of approximately 200-500 tons), a nacelle 300 (approximately 300-500 tons), a rotor hub 400, and a plurality of rotor blades 500a-500c.

[0034] The tower 200 comprises a tubular (eg cylindrical) structure having a longitudinal or vertical axis Zt. The lower end (not shown) of the tower 200 is fixed in the seabed. The nacelle 300 is mounted to the tower 200. Although not shown in FIG. Figure 1 1 , but a tubular (e.g., cylindrical) structure 301 of the nacelle 300 having a longitudinal or vertical axis Zn extends downwardly from the lower surface of the nacelle 300. The tubular structure 301 of the nacelle 300 includes a flange portion 303 that is bolted to a complementary flange portion 201 (not shown) at the upper end of the tower 200, as will be described later. The nacelle 300 also includes a housing 301 that houses a generator (not shown). A rotor hub 400 extends from the nacelle 300 and is connected to the generator via a horizontally arranged shaft (not shown) having an axis Xs that is substantially perpendicular to the longitudinal axis Zt of the tower 200. Rotor blades 500a-500c are attached to the rotor hub 400. During use of the wind turbine 100, wind forces acting on the rotor blades 500a-500c cause the rotor blades 500a-500c to rotate about the horizontal axis Xs, thereby driving the generator via the shaft to generate electrical energy.

[0035] The mounting of the nacelle 300 on the tower 200 is performed with the aid of an alignment tool which will now be described.

[0036] Reference Figure 2 and Figure 3 The first exemplary alignment tool 600 includes a support component and a guide component connected together by a biasing component. In this first example, the support component includes a first support member 601a and a second support member 601b. In this first example, the guide component includes a first guide member 603a and a second guide member 603b. In this first example, the biasing component includes a first biasing member and a second biasing member. In this first example, each of the first and second biasing members includes a coil spring 605a, 605b.

[0037] In this first example, each of the first support member 601a and the second support member 601b comprises steel. In this first example, each of the first support member 601a and the second support member 601b comprises a plate-like construction including a plurality of bends defining a plurality of portions of the support members 601a, 601b. In this regard, the attachment portion extends horizontally (i.e., substantially perpendicular to the longitudinal axis Zt of the tower 200) along the lower surface of the flange portion 201 of the tower 200. The attachment portion includes through holes for receiving bolts to secure the support members 601a, 601b to the flange portion 201 of the tower 200. As shown in Figure 3 As can be seen in FIG, for this purpose, the flange portion 201 is provided with dedicated, radially inner rows of through holes 203. (For the sake of clarity, only the support members 601a, 601b of the alignment tool 600 are shown.) Figure 3 ) The flange portion 201 may be wider than conventional to accommodate the radially inner rows of through-holes 203 inside the conventional flange bolt holes 205. Each of the first and second support members 601a, 601b is secured to the flange portion 201 of the tower 200 by bolts (not shown) that pass through through-holes in the attachment portions of the support members 601a, 601b and through-holes in the flange portion 201 and are fastened at their ends using nuts.

[0038] The radially outer upright portions of the support members 601a, 601b extend vertically upward from the attachment portion, such as substantially parallel to the longitudinal axis Zt of the tower 200. The inclined portions of the support members 601a, 601b extend upward and inward 200 from the radially outer upright portions toward the longitudinal axis Zt, so as to be inclined relative to the radially outer upright portions and the longitudinal axis Zt. The radially inner upright portion extends vertically upward from the inclined portion, such as substantially parallel to the radially outer upright portion and the longitudinal axis Zt of the tower 200. Thus, the inclined portion is also inclined relative to the radially inner upright portion.

[0039] Therefore, each of the first support member 601a and the second support member 601b is attached to the flange portion 201 of the upper end of the tower 200 so as to extend upward in the axial direction from the upper end of the tower 200. The central longitudinal axis or vertical axis Za of the alignment tool 600 is defined equidistantly between the fixed first support member 601a and the second support member 601b. Figure 3As best seen in FIG, each portion of each of the first and second support members 601a, 601b includes an inner surface, i.e., on the side of the support members 601a, 601b closest to the longitudinal axis Za of the alignment tool 600, and an outer surface, i.e., on the side of the support members 601a, 601b farthest from the longitudinal axis Za of the alignment tool 600. In this first example, the outer surface of the radially outer upstanding portion of each of the first and second support members 601a, 601b is curved so as to conform to the curved inner wall 301a of the tubular structure 301 of the nacelle 300. In this first example, the horizontal distance between the curved outer surfaces of the radially outer upstanding portions of the first and second support members 601a, 601b is approximately equal to the inner diameter of the tubular structure 301 of the nacelle 300.

[0040] In this first example, each of the first and second coil springs 605a, 605b comprises steel. A first end of each coil spring 605a, 605b is attached to the outer surface of the radially inner upright portion of a corresponding one of the first and second guide members 603a, 603b. Each coil spring 605a, 605b extends radially outward such that the axis of the coil spring 605a, 605b is substantially perpendicular to the longitudinal axes Za, Zt of the alignment tool 600 and tower 200. In other words, each coil spring 605a, 605b is arranged horizontally. Furthermore, each coil spring 605a, 605b connects one of the first and second guide members 603a, 603b to one of the first and second support members 601a, 601b. Furthermore, each coil spring 605a, 605b is positioned between the corresponding one of the support members 601a, 601b and the corresponding one of the guide members 603a, 603b.

[0041] In this first example, each of the first and second guide members 603a, 603b comprises steel. In this first example, each of the first and second guide members 603a, 603b comprises a plate-like construction including a curved portion defining two portions of the guide members 603a, 603b. An upright guide portion is connected to the second end of a respective one of the coil springs 605a, 605b and extends vertically upward, such as substantially parallel to the longitudinal axis Za of the alignment tool 600 and the longitudinal axis Zt of the tower 200. An inclined guide portion of the guide members 603a, 603b extends upward and inward from the upright guide portion toward the longitudinal axis Za of the alignment tool 600 and the longitudinal axis Zt of the tower 200, such as being inclined relative to the upright guide portion and the longitudinal axes Za, Zt.

[0042] Each portion of each of the first and second guide members 603a, 603b includes an inner surface, i.e., the side of the guide members 603a, 603b closest to the longitudinal axis Za of the alignment tool 600 and the longitudinal axis Zt of the tower 200, and an outer surface, i.e., the side of the guide members 603a, 603b furthest from the longitudinal axes Za, Zt. In this first example, the intersection between the outer surfaces of the upright and inclined guide portions of each of the first and second guide members 603a, 603b is rounded or curved. In this first example, the outer surface of the upright portion of each of the first and second guide members 603a, 603b is curved to conform to the curved inner wall 301a of the tubular structure 301 of the nacelle 300. In this first example, when the coil springs 605a, 605b are in a neutral position (i.e., neither extended nor compressed), the horizontal distance between the curved outer surfaces of the upright guide portions of the first and second guide members 603a, 603b is approximately equal to the inner diameter of the tubular structure 301 of the nacelle 300. Consequently, the horizontal distance between the curved outer surfaces of the upright guide portions of the first and second guide members 603a, 603b is also approximately equal to the horizontal distance between the curved outer surfaces of the radially outer upright portions of the first and second support members 601a, 601b.

[0043] Therefore, the inner surface of the upright guide portion of each of the first guide member 603a and the second guide member 603b is opposite to the outer surface of the radially inner upright portion of the corresponding support member 601a, 601b, and the inner surface of the upright guide portion is connected to the outer surface of the radially inner upright portion via the corresponding one of the coil springs 605a, 605b. Therefore, the inner surface of the upright guide portion, the outer surface of the radially inner upright portion, and the corresponding one of the coil springs 605a, 605b are located in the same plane, that is, in the same horizontal plane.

[0044] In this first example, respective portions of the connector element 607 extend upwardly and inwardly 200° from the angled guide portions of the first and second guide members 603a, 603b, such as at an angle relative to the longitudinal axis Za of the alignment tool 600 and the longitudinal axis Zt of the tower 200. The distal ends of the portions of the connector element 607 coincide to form an apex of the connector element 607 at the top or uppermost portion of the alignment tool 600. In this first example, the apex coincides with the longitudinal axes Za, Zt of the alignment tool 600 and the tower 200. In this first example, the connector element 607 is rigid to form a rigid connection between the first and second guide members 603a, 603b.

[0045] As in Figure 2 As can be seen in the figure, no portion or part of the alignment tool 600 extends laterally from the upper end of the tower 200. That is, the entirety of the alignment tool 600 is contained within a circle projected from the circumferential edge of the upper end of the tower 200. Furthermore, each of the first and second guide members 603a, 603b, the coil springs 605a, 605b, and the connector element 607 is positioned axially spaced from the extreme end or tip of the tower 200, along with the main portions of the first and second support members 601a, 601b, with only the lowest portions of the first and second support members 601a, 601b located within the volume of the tubular tower 200. Furthermore, the alignment tool 600 is functionally symmetrical about the longitudinal axes Za, Zt of the alignment tool 600 and the tower 200.

[0046] The use of the alignment tool 600 for mounting the nacelle 300 on the tower 200 will now be described.

[0047] Refer again Figure 2 The alignment tool 600 is shown attached to the flange portion 201 of the upper end of the tower 200, as described above. Thus, the longitudinal axis Za of the alignment tool 600 coincides with, or lies along, the longitudinal axis Zt of the tower 200. Initially, the tool is in a static state, with the coil springs 605a, 605b in a neutral position, neither extended nor compressed. Consequently, the first and second guide members 603a, 603b are equidistant from the longitudinal axis Za of the alignment tool 600 and also from the longitudinal axis Zt of the tower 200.

[0048] The nacelle 300 is initially positioned above the tower 200, for example using a crane, so that the tower 200 and the tubular structure 301 of the nacelle 300 are approximately vertically aligned. The nacelle 300 is then lowered toward the tower 200. Due to the disturbing forces exerted on the nacelle 300 by the crosswind, the nacelle 300 may move horizontally (i.e., left and right) as well as vertically (i.e., downward). As a result, the longitudinal axis Zn of the tubular structure 301 of the nacelle 300 is displaced laterally toward the longitudinal axis Zt of the tower 200, for example, in Figure 2 In the sense of , the lateral displacement is shifted to the right of the longitudinal axis Zt of the tower 200. Depending on the strength of the side wind, the lateral displacement can be up to about 2 meters.

[0049] Once the flange portion 303 of the tubular structure 301 of the nacelle 300 (i.e., the lowest portion of the nacelle 300) is below the level of the apex of the connector element 607 of the alignment tool 600, i.e., the uppermost portion of the alignment tool 600, lateral displacement of the nacelle 300 will be limited by the presence of the alignment tool 600. That is, as the nacelle 300 is lowered, lateral movement of the nacelle 300 may cause a portion of the circular flange portion 303 to contact one of the inclined portions of the connector element 607, i.e., in this example, the left portion of the connector element 607. In this way, lateral movement of the nacelle 300 is limited by the inclined portion of the connector element 607. For example, at this stage, lateral movement of the nacelle 300 may be limited to approximately 0.5 meters.

[0050] As the nacelle 300 travels further downward, said portion of the flange portion 303 will be guided along the surface of the inclined portion of the connector element 607 (i.e., under the weight of the nacelle 300), so that the longitudinal axis Zn of the tubular structure 301 of the nacelle 300 will move laterally, to the left, towards the longitudinal axis Za of the alignment tool 600 and thereby also towards the longitudinal axis Zt of the tower 200. Thus, even when the nacelle 300 is still subject to lateral movement due to side winds, the inclined portion of the connector element 607 acts to generally guide the nacelle 300 towards axial alignment with the tower 200.

[0051] As the nacelle 300 is lowered still further towards the tower 200, said portion of the flange portion 303 of the tubular structure 301 will be guided on the inclined guide portion of the associated guide member 603a, 603b, i.e. the left guide member 603a in this example, until said portion of the flange portion 303 reaches the intersection with the upright guide portion of that guide member 603a. Substantially simultaneously, the opposing portion of the flange portion 303 will contact the intersection between the upright guide portion and the inclined guide portion of the other guide member 603a, 603b, i.e. the right guide member 603b in this example. The curved intersection helps to guide the nacelle 300 further downwards, so that the horizontally opposing portions of the inner wall 301a of the tubular structure 301 of the nacelle 300 both come into sliding contact with the curved outer surface of the upright guide portion of one of the guide members 603a, 603b. This is Figure 2 In this case, the tubular structure 301 of the nacelle 300 is substantially axially aligned with the tower 200. That is, the longitudinal axis Zn of the tubular structure 301 is at least substantially axially aligned with the longitudinal axis Zt of the tower 200.

[0052] In this position, the nacelle 300 is still subject to lateral displacement due to the disturbing forces exerted by the crosswind on the nacelle 300. However, the wind forces are counteracted by the coil springs 605a, 605b, as described below. For example, a crosswind may exert a force on the nacelle 300 that causes the nacelle 300 to move in a lateral direction. Figure 2 , meaning it will shift leftward. Wind forces will be transmitted via the inner wall 301a of the tubular structure 301 of the nacelle 300 to the upright portion of the right guide member 603b. As a result, the right guide member 603b will move laterally toward the longitudinal axis Za, Zt of the alignment tool 600 and the tower 200, i.e., in this example, to the left, thereby compressing the coil spring 605b of the right guide member 603b. Because the first and second guide members 603a, 603b are rigidly connected together via the connector element 607, the left guide member 603a will simultaneously move laterally away from the axis Za, Zt of the alignment tool 600 and the tower 200, i.e., in this example, to the left, thereby extending the coil spring 605a of the left guide member 603a.

[0053] It will be appreciated that the magnitude of the resistance of the coil springs 605a, 605b (i.e., the resistance of the coil springs 605a, 605b to displacement from their neutral position) will increase linearly as the coil springs 605a, 605b are compressed / expanded due to the lateral movement of the nacelle 300. Of course, the nacelle 300 will only move laterally when the magnitude of the wind force exerted on the nacelle 300 exceeds the resistance of the coil springs 605a, 605b.

[0054] It will be appreciated that the lateral displacement of the left guide member 603a will be equal to the lateral displacement of the right guide member 603b. For example, the lateral displacement may be approximately 5 millimeters. It will be further appreciated that, due to the lateral displacement, the first and second guide members 603a, 603b will no longer be equidistant from the longitudinal axes Za, Zt of the alignment tool 600 and tower 200, but will instead be at different horizontal distances, with the right guide member 603b being closer to the longitudinal axes Za, Zt and the left guide member 603a being further away from the longitudinal axes Za, Zt in this example. However, due to the rigid connection between the first and second guide members 603a, 603b, the horizontal distance between the first and second guide members 603a, 603b remains substantially unchanged despite the lateral displacement.

[0055] As the instantaneous crosswind force applied to the nacelle 300 decreases or is removed, the energy stored in the coil springs 605a, 605b causes the lateral displacement of the nacelle 300 to reverse. That is, in this example, when the right coil spring 605b extends and the left coil spring 605a retracts, the nacelle 300 will move laterally to the right. As the coil springs 605a, 605b reach their intermediate state—neither compressed nor extended—the first and second guide members 603a, 603b return to their original positions relative to the longitudinal axes Za, Zt of the alignment tool 600 and tower 200. Because the upright portions of the first and second guide members 603a, 603b remain in contact with the inner wall 301a of the tubular structure 301 of the nacelle 300, the nacelle 300 similarly returns to its original position relative to the longitudinal axes Za, Zt. That is, the tubular structure 301 of the nacelle 300 is once again at least approximately axially aligned with the tower 200.

[0056] Thus, the coil springs 605a, 605b act to counteract the crosswind, bringing the nacelle 300 back into axial alignment with the tower 200. That is, the coil springs 605a, 605b tend to bias the nacelle 300 into axial alignment with the tower 200. In other words, the coil springs 605a, 605b act to center the tubular structure 301 of the nacelle 300 relative to the tower. Furthermore, the coil springs 605a, 605b provide a restoring force.

[0057] In addition to the centering effect, the coil springs 605a, 605b tend to damp lateral oscillations or vibrations of the nacelle 300 caused by side winds. As a result of the damping, the impact of any contact between the nacelle 300 and the tower 200 is reduced or eliminated as the nacelle 300 is lowered onto the tower 200.

[0058] As described above, as the nacelle 300 is lowered toward the tower 200, the rate of descent of the nacelle 300 may cause the flange portion 303 of the tubular structure 301 to reach the inclined portions of the support members 601a, 601b before the coil springs 605a, 605b have returned to their neutral positions. That is, in this example, the flange portion 303 may contact the outer surface of the inclined portion of the right support member 601b, while the tubular structure 301 of the nacelle 301 is still not aligned with the tower 200, i.e., in this example, the longitudinal axis Zn is still to the left of the longitudinal axis Zt of the tower 200. In this situation, the flange portion 303 of the tubular structure 301 will be guided rightward along the inclined portion of the support member 601b (i.e., under the weight of the nacelle 300). Therefore, the inclined portion of the support member 601b may assist the spring force in returning the tubular structure 301 of the nacelle 300 to substantial axial alignment with the tower 200.

[0059] Now also refer to Figure 4 Nacelle 300 is lowered further until opposing portions of the inner wall of flange portion 303 of tubular structure 301 each come into sliding contact with the curved outer surface of a corresponding radially outer upright portion of support members 601a, 601b. At this stage, further lateral movement of nacelle 300 is prevented by the radially outer upright portions of support members 601a, 601b, which are in fixed relation to tower 200. As nacelle 300 descends further, the end of flange portion 303 contacts flange portion 201 at the upper end of tower 200, thereby causing nacelle 300 to rest on top of tower 200. In this resting position, opposing portions of the inner wall of flange portion 303 of tubular structure 301 abut against the curved outer surface of the radially outer upright portions of support members 601a, 601b, resulting in substantially perfect axial alignment of tubular structure 301 of nacelle 300 with tower 200.

[0060] Thus, as the nacelle 200 is lowered towards the tower 200 , the alignment tool 600 provides for the tubular structure 301 of the nacelle 300 to be gradually guided into axial alignment with the tower 200 , while providing for damping of oscillations or vibrations of the nacelle 300 and tower 200 structures caused by crosswinds.

[0061] With the nacelle 300 resting on the tower 200, if necessary, the nacelle 300 can be yawed, i.e., rotated about the longitudinal axes Zn, Zt of the nacelle 300 and the tower 200, in order to align the bolt holes of the flange portion 303 of the tubular structure 301 of the nacelle 300 with the bolt holes of the flange portion 201 at the upper end of the tower 200. In this regard, the flange portion 303 of the tubular structure 301 can be described as a yaw interface between the nacelle 300 and the tower 200. Once the bolt holes are aligned, bolts can be installed in the bolt holes to securely attach the nacelle 300 to the tower 200.

[0062] The alignment tool 600 is preferably then removed to improve access to the structure by personnel and to allow the alignment tool 600 to be reused with another wind turbine. To remove the alignment tool 600, the nuts are loosened and the bolts are withdrawn from the through holes in the flange portion 201 of the tower 200 and the attached portions of the support members 601a, 601b.

[0063] While the alignment tool includes a connector element that rigidly connects the first and second guide members in the first example described above, in another example, the connector element is omitted. In such an example, the first and second guide members can move independently because compression of one of the coil springs (i.e., due to lateral movement of the nacelle) does not cause extension of the other coil spring. Consequently, the horizontal distance between the first and second guide members 603a, 603b can vary in the event of lateral displacement of the nacelle 300 relative to the longitudinal axes Za, Zt of the alignment tool 600 and tower 200.

[0064] In the first example described above, when the coil springs are in a neutral position (i.e., neither compressed nor tensioned), the horizontal distance between the curved outer surfaces of the upright guide portions of the first and second guide members is approximately equal to the inner diameter of the tubular structure of the nacelle. In another example, when the coil springs are in a neutral position (i.e., neither compressed nor tensioned), the horizontal distance between the curved outer surfaces of the upright guide portions of the first and second guide members is greater than the inner diameter of the tubular structure of the nacelle. In such an example, lowering the nacelle onto the upright guide portions causes the coil springs to compress, i.e., preloads the first and second guide members such that the first and second guide members will tend to exert an outward radial force on the inner wall of the tubular structure of the nacelle. In this example, the preloaded position of the coil springs can be considered their neutral position.

[0065] While in the first example described above, the biasing member of the alignment tool comprises a coil spring, different types of springs or other resilient elements may be used instead. All of these are within the scope of the claimed invention, provided they function to provide a restoring force to center the tubular structure of the nacelle relative to the tower.

[0066] Now refer to Figure 5 A second exemplary alignment tool 600' is described. The second example is generally similar to the first example, except that in the second example, the biasing member includes first and second hydraulic cylinders 609a, 609b, rather than first and second coil springs.

[0067] In this second example, each of the first and second hydraulic cylinders 609a, 609b is attached to a radially inner upright portion of a respective one of the support members 601a, 601b so as to be in fixed relation thereto. Each of the first and second hydraulic cylinders 609a, 609b contains a hydraulic fluid, such as oil, and includes a movable, horizontally arranged piston 609a1, 609b1 having a rod portion connected to an upright guide portion of a respective one of the first and second guide members 603a, 603b. Thus, each of the first and second hydraulic cylinders 609a, 609b connects one of the first and second guide members 603a, 603b to one of the first and second support members 601a, 601b. Furthermore, each of the first and second hydraulic cylinders 609a, 609b is positioned between a respective one of the support members 601a, 601b and a respective one of the guide members 603a, 603b.

[0068] like Figure 5 As shown, each piston 609a1, 609b1 is in an intermediate position, with the head of the piston 609a1, 609b1 midway between the ends of the respective hydraulic cylinders 609a, 609b. The first hydraulic cylinder 609a and the second hydraulic cylinder 609b are fluidically connected via a hydraulic circuit comprising first and second hydraulic lines 611a, 611b and first and second valves 613a, 613b. A control unit (not shown) is connected to the first and second valves 613a, 613b and is arranged to control the pressure of the hydraulic fluid in the first and second hydraulic cylinders 609a, 609b. Also in this second example, the connector element 607 is preferably omitted from the first and second guide members 603a, 603b.

[0069] As already described above, when the nacelle 300 is lowered towards the tower 200, there comes a stage where the horizontally opposite portions of the inner wall 301a of the tubular structure 301 of the nacelle 300 both come into contact with the curved outer surface of the upright guide portion of one of the guide members 603a, 603b. Figure 5 in (and in Figure 2 conditions shown in ).

[0070] As described above, in this case, the tubular structure 301 of the nacelle 300 is generally axially aligned with the tower 200. That is, the longitudinal axis Zn of the tubular structure 301 is at least generally axially aligned with the longitudinal axis Zt of the tower 200. Also in this case, the nacelle 300 experiences lateral displacement due to the forces exerted on it by the crosswind. However, in this second example, the wind forces are counteracted by the first and second hydraulic cylinders 609a, 609b, as described below.

[0071] For example, in the manner already described above, a crosswind may exert a force on the nacelle 300 that causes the nacelle 300 to Figure 5 The wind force will be transferred to the upright portion of the right guide member 603b via the inner wall 301a of the tubular structure 301 of the nacelle 300. As a result, the right guide member 603b will move laterally toward the longitudinal axis Za, Zt of the alignment tool 600 and the tower 200, i.e., to the left in this example, thereby also moving the piston 609b1 of the right hydraulic cylinder 609b toward the longitudinal axis Za, Zt.

[0072] The movement of piston 609b1 causes hydraulic fluid to shift from the cylinder volume in front of piston 609b1 of right hydraulic cylinder 609b to the cylinder volume behind piston 609a1 of left hydraulic cylinder 609a via second hydraulic line 611b and second valve 613b. Consequently, fluid pressure is applied to piston 609a1 of left hydraulic cylinder 609a, causing piston 609a1 to move laterally, away from the longitudinal axes Za, Zt of alignment tool 600 and tower 200, i.e., to the left in this example. The movement of piston 609b1 causes hydraulic fluid to shift from the cylinder volume in front of piston 609a1 of left hydraulic cylinder 609a to the cylinder volume behind piston 609b1 of right hydraulic cylinder 609b via first hydraulic line 611a and first valve 613a.

[0073] During the lateral displacement of the pistons 609a1, 609b1 of the first and second hydraulic cylinders 609a, 609b (to the left in this example), the first and second hydraulic cylinders 609a, 609b exert an opposing force or resistance (to the right in this example) to resist the lateral movement of the nacelle 300 (to the left). The pressure of the hydraulic fluid in the first and second hydraulic cylinders 609a, 609b is controlled by a control unit so that the resistance maintains a constant magnitude. That is, unlike the coil springs 605a, 605b of the first example, in the second example, the resistance of the first and second hydraulic cylinders 609a, 609b does not increase as the nacelle 300 moves laterally, but rather remains constant. Of course, the nacelle 300 will only move laterally if the magnitude of the wind force exerted on the nacelle 300 exceeds the resistance of the first and second hydraulic cylinders 609a, 609b.

[0074] It will be appreciated that the lateral displacement of the left guide member 603a will be equal to the lateral displacement of the right guide member 603b. For example, the lateral displacement may be approximately 5 millimeters. It will be further appreciated that, due to the lateral displacement, the first and second guide members 603a, 603b will no longer be equidistant from the longitudinal axes Za, Zt of the alignment tool 600 and tower 200, but will instead be at different horizontal distances, with the right guide member 603b being closer to the longitudinal axes Za, Zt and the left guide member 603a being further away from the longitudinal axes Za, Zt in this example. However, due to the equal lateral displacement of the pistons 609a1, 609b1 and the flow of hydraulic fluid between the first and second hydraulic cylinders 609a, 609b, the horizontal distance between the first and second guide members 603a, 603b remains substantially unchanged despite the lateral displacement of the nacelle 300.

[0075] When the momentary crosswind force exerted on nacelle 300 decreases or is removed, the constant opposing force or resistance exerted by hydraulic cylinders 609a, 609b causes the lateral displacement of nacelle 300 to reverse. That is, piston 609a1 of left hydraulic cylinder 609a moves toward longitudinal axis Za, Zt of alignment tool 600 and tower 200, i.e., to the right in this example. The movement of piston 609a1 causes hydraulic fluid to shift from the cylinder volume in front of piston 609a1 of left hydraulic cylinder 609a to the cylinder volume behind piston 609b1 of right hydraulic cylinder 609b via second hydraulic line 611b and second valve 613b. Consequently, fluid pressure is applied to piston 609b1 of right hydraulic cylinder 609b, causing piston 609b1 to move laterally away from longitudinal axis Za, Zt of alignment tool 600 and tower 200, i.e., to the right in this example. The movement of the piston 609b1 causes the hydraulic fluid to be displaced from the cylinder volume in front of the piston 609b1 of the right hydraulic cylinder 609b to the cylinder volume behind the piston 609a1 of the left hydraulic cylinder 609a via the first hydraulic line 611a and the first valve 613a.

[0076] As a result, the nacelle 300 will move laterally to the right under constant resistance due to the rightward movement of the pistons 609a1, 609b1. When the pistons 609a1, 609b1 reach their intermediate positions (i.e., the heads of the pistons 609a1, 609b1 are at the centers of their respective hydraulic cylinders 609a, 609b), the first and second guide members 603a, 603b return to their original positions relative to the longitudinal axes Za, Zt of the alignment tool 600 and the tower 200. Because the upright portions of the first and second guide members 603a, 603b remain in contact with the inner wall 301a of the tubular structure 301 of the nacelle 300, the nacelle 300 likewise returns to its original position relative to the longitudinal axes Za, Zt. That is, the tubular structure 301 of the nacelle 300 is at least approximately axially aligned with the tower 200.

[0077] Thus, hydraulic cylinders 609a, 609b act to counteract the crosswind force in order to axially align nacelle 300 with tower 200. In other words, hydraulic cylinders 609a, 609b provide a restoring force. In other words, hydraulic cylinders 609a, 609b tend to bias nacelle 300 into axial alignment with tower 200. In other words, hydraulic cylinders 609a, 609b serve to center tubular structure 301 of nacelle 300 relative to the tower.

[0078] In addition to the centering effect, the hydraulic cylinders 609a, 609b tend to dampen lateral oscillations or vibrations of the nacelle 300 caused by crosswinds. As a result of this damping, the impact of any contact between the nacelle 300 and the tower 200 as the nacelle 300 is lowered onto the tower 200 is reduced or eliminated. Furthermore, the first and second valves 613a, 613b can be adjusted to vary the degree of resistance and damping provided by the first and second hydraulic cylinders 609a, 609b.

[0079] It should be appreciated that the second exemplary alignment tool 600 is similar to the first exemplary alignment tool 600 with respect to further lowering of the nacelle 300 and final alignment of the nacelle 300 with the tower 200. Therefore, these operations will not be described herein with respect to the second exemplary alignment tool 600.

[0080] A variation of the second exemplary alignment tool 600' is Figure 6 This variation differs from the installation of the first hydraulic cylinder 609a and the second hydraulic cylinder 609. In this variation, the support members 601a, 601b are simplified compared to the second example because they include a single upright portion.

[0081] As in the second example, each of the first and second hydraulic cylinders 609a and 609 is attached to a corresponding one of the support members 601a and 601b, such as in a fixed relationship thereto. However, unlike the second example, in a variation, the main body of each of the first and second hydraulic cylinders 609a and 609 is located radially inward of the corresponding one of the support members 601a and 601b. Similar to the second example, in a variation, the rod portion of the piston 609a1 and 609b1 of each of the first and second hydraulic cylinders 609a and 609b is connected to a corresponding one of the first and second guide members 603a and 603b. However, in this variation, the rod portion of the piston 609a1 and 609b1 extends through the corresponding support member 601a and 601b to the corresponding guide member 603a and 603b. In this manner, each of the first and second guide members 603a, 603b is connected to a corresponding one of the support members 601a, 601b through a corresponding one of the first and second hydraulic cylinders 609a, 609b.

[0082] Aside from the structural differences noted above, this variation is functionally similar to the second exemplary alignment tool 600' with respect to the operation of the first and second hydraulic cylinders 609a, 609. Therefore, the operation will not be described herein with respect to this variation.

[0083] While the support assembly includes two opposing support members in the above examples, in other examples, the support assembly includes more than two support members. In such examples, essentially any number of support members can be attached to the upper end of the tower, with the support members spaced circumferentially from one another, preferably equally spaced. In one such example, three support members are spaced circumferentially 120 degrees apart. In another such example, four support members are spaced circumferentially 90 degrees apart. In another such example, six support members are spaced circumferentially 60 degrees apart. In another such example, eight support members are spaced circumferentially 45 degrees apart. In these examples, each of the support members can be connected to a guide member via a biasing member in the manner described above. Also in these examples, the guide members can all be connected together via a single connector element, such as a conical or inverted bowl or cap, for guiding the nacelle as it is lowered toward the tower. Furthermore, in another example, the support assembly and / or corresponding guide assembly include only a single support / guide member. In one such example, the support member is generally circular, such as extending around the entire circumference of the upper end of the tower. In this example, the guide member can be in the form of a conical or inverted bowl or cap. Also in this example, the guide member is connected to the support member by one or more biasing components.

[0084] In the above example, the horizontal distance between the curved outer surfaces of the radially outer upright portions of the first and second support members is approximately equal to the inner diameter of the tubular structure of the nacelle. Therefore, when the nacelle is resting on the tower, the inner wall of the tubular structure of the nacelle abuts the curved outer surfaces of the radially outer upright portions, preventing the nacelle from lateral movement relative to the tower when subjected to crosswinds. In another example, the horizontal distance between the curved outer surfaces of the radially outer upright portions of the first and second support members is less than the inner diameter of the tubular structure of the nacelle. In such an example, the support components further include positioning members, which can be attached to a flange portion of the tower in a similar manner to the support members, such as by being circumferentially spaced between the support members. The positioning members each include an upright portion having a curved outer surface configured to conform to the curved inner wall of the tubular structure of the nacelle. When the positioning members are attached to the flange of the tower, the horizontal distance between the curved outer surfaces of the upright portions of the opposing positioning members is approximately equal to the inner diameter of the tubular structure of the nacelle. Thus, when the nacelle is lowered onto the tower, the inner wall of the nacelle's tubular structure abuts the curved outer surface of the upright portion of the positioning member. Consequently, when subjected to crosswinds, the nacelle is prevented from lateral movement relative to the tower. Thus, the positioning member provides an alternative means of restraining lateral movement of the nacelle when in its resting position on the tower.

[0085] In the above example, the flange portion of the tower is provided with dedicated, radially inner rows of bolt holes for the purpose of attaching the support member of the alignment tool. As already explained, this can be achieved by providing a wider-than-conventional flange portion of the tower. In another example, it can be adapted for use with a conventional, i.e., non-widened, flange portion, omitting the radially inner rows of bolt holes. Instead, threaded bolts are used to secure the attachment portion of the support member to threaded holes (optionally, blindly threaded holes) provided in the flange portion. Alternatively, the holes provided in the flange portion are unthreaded, and expansion bolts are used to secure the attachment portion of the support member in the unthreaded holes.

[0086] While the alignment tool has been described in the above examples with respect to axial alignment of tubular towers and tubular portions of a nacelle, it should be understood that the alignment tool is equally applicable to axial alignment of other tubular structures of a wind turbine (e.g., tubular segments or sections of a wind turbine tower). It should also be understood that the alignment tool is also applicable to non-cylindrical tubular structures, such as oval, elliptical, or rectangular tubular structures of a wind turbine.

[0087] It will be understood that the present invention has been described with respect to its preferred embodiments and that it can be modified in many different ways without departing from the scope of the present invention as defined by the appended claims.

Claims

1. A tool (600; 600') for aligning a tubular structure of a wind turbine, comprising: a support member for attaching the tool (600; 600') to an end region of the first tubular structure (200) so as to extend axially outwardly from the end region; as well as a guide member connected to the support member by a biasing member and adapted to engage an inner wall (301a) of the second tubular structure (301), wherein the biasing member is arranged to push the guiding member to exert a radial force on the inner wall (301a) when the second tubular structure (301) moves axially toward the first tubular structure (200), thereby guiding the second tubular structure (301) to axially align with the first tubular structure (200), The tool is configured such that, in use, the guide member and the biasing member are located outside the endmost portion of the first tubular structure (200) and are axially spaced apart from the endmost portion of the first tubular structure (200).

2. The tool (600) according to claim 1, wherein The biasing member includes a resilient element.

3. The tool (600') according to claim 1, wherein The biasing member includes a hydraulic element.

4. The tool (600; 600') according to any one of claims 1 to 3, wherein: The guide member is configured to be positioned radially outside the support member relative to a longitudinal axis (Zt) of the first tubular structure (200); as well as The biasing member is arranged to urge the guide member to exert an outward radial force on the inner wall (301a).

5. The tool (600; 600') according to claim 4, wherein At least a portion of the biasing member is located between the supporting member and the guiding member.

6. The tool (600; 600') according to claim 5, wherein The support component includes a plurality of support members (601a, 601b) configured to be attached to the end region of the first tubular structure (200) so as to be spaced around the end region of the first tubular structure (200).

7. The tool (600; 600') according to claim 6, wherein Each of the support members (601a, 601b) comprises: an attachment portion for attachment to the end region of the first tubular structure (200) so as to extend substantially perpendicularly relative to the longitudinal axis (Zt) of the first tubular structure (200); a first upstanding portion extending substantially perpendicularly from the attachment portion and adapted to be positioned at an outer radial position relative to the longitudinal axis (Zt) of the first tubular structure (200); a second upstanding portion laterally offset from the first upstanding portion and adapted to be positioned at an inner radial position relative to the longitudinal axis (Zt) of the first tubular structure (200); and An inclined portion connects the first upright portion and the second upright portion.

8. The tool (600; 600') according to claim 7, wherein The attachment portion of each of the support members (601a, 601b) and the first upright portion are configured such that, when the support members (601a, 601b) are attached to the end region of the first tubular structure (200), the distance between the opposing pairs of upright portions of the support members (601a, 601b) is substantially the same as the inner diameter of the second tubular structure (301) so as to provide a tight fit between the upright portions and the inner wall (301a) of the second tubular structure (301).

9. The tool (600; 600') according to claim 7, wherein The guide component comprises a plurality of guide members (603a, 603b), and the biasing component comprises a plurality of biasing elements, each of the guide members (603a, 603b) being connected to the second upright portion of a respective one of the support members (601a, 601b) via a respective one of the biasing elements.

10. The tool (600; 600') according to claim 9, wherein Each of the guide members (603a, 603b) comprises: an upstanding portion for positioning in a substantially parallel relationship with the second upstanding portion of a corresponding one of the support members (601a, 601b); and An inclined portion extends from the upright portion.

11. The tool (600; 600') according to claim 10, comprising a connector part (607) connecting the inclined portions of the guide members (603a, 603b) together.

12. The tool (600) according to claim 10, wherein Each of the biasing elements comprises a coil spring (605a, 605b), a first end of the coil spring (605a, 605b) being attached to the second upright portion of the respective one of the support members (601a, 601b), and a second end of the coil spring (605a, 605b) being attached to the upright portion of the respective one of the guide members (603a, 603b), such that an axis of the coil spring (605a, 605b) is substantially perpendicular to the upright portion.

13. The tool (600') according to claim 10, wherein Each of the biasing elements comprises a hydraulic cylinder (609a, 609b), each of the hydraulic cylinders (609a, 609b) being arranged in fluid communication with the other of the hydraulic cylinders (609a, 609b).

14. The tool (600') according to claim 13, wherein; The body of each of the hydraulic cylinders (609a, 609b) is attached to the second upright portion of the respective one of the support members (601a, 601b); and The rod of the piston of the hydraulic cylinder (609a, 609b) is movable relative to the body and is attached to the upright portion of the respective one of the guide members (603a, 603b) such that the axis of the hydraulic cylinder (609a, 609b) is substantially perpendicular to the upright portion.

15. The tool (600) of claim 1, wherein The biasing member is a spring.

16. The tool (600) of claim 1, wherein The biasing member is a coil spring.

17. The tool (600') according to claim 1, wherein The biasing member is a hydraulic cylinder.

18. The tool (600; 600') according to claim 6, wherein The plurality of support members (601a, 601b) are configured to be equally spaced around the end region of the first tubular structure (200).

19. The tool (600; 600') according to claim 10, wherein The inclined portions of the guide members (603a, 603b) are positioned in a substantially parallel relationship with the inclined portions of the corresponding ones of the support members (601a, 601b).

20. The tool (600; 600') according to claim 11, wherein The connector component (607) comprises a generally conical shape.

21. A wind turbine generator at least partially installed and comprising a tool according to any one of claims 1 to 20.

22. A method of installing a wind turbine generator, comprising: attaching a support member of an alignment tool (600; 600') to an end region of a first tubular structure (200) of the wind turbine generator so as to extend axially outwardly from said end region, said alignment tool (600; 600') comprising a guide member connected to said support member by a biasing member and adapted to engage an inner wall (301a) of a second tubular structure (301) of the wind turbine generator, wherein said guide member and said biasing member are located outside of and axially spaced apart from an endmost portion of said first tubular structure (200); and The second tubular structure (301) is moved axially toward the first tubular structure (200) so that the inner wall (301a) engages the guide member of the alignment tool (600; 600'), thereby enabling the biasing member to push the guide member to exert a radial force on the inner wall (301a) so as to guide the second tubular structure (301) into substantial axial alignment with the first tubular structure (200).

23. The method of installing a wind turbine generator according to claim 22, wherein: The biasing member of the alignment tool (600; 600') comprises a plurality of hydraulic cylinders (609a, 609b), each of the hydraulic cylinders (609a, 609b) being arranged in fluid communication with another of the hydraulic cylinders (609a, 609b); and The method includes controlling the hydraulic cylinders (609a, 609b) to push the guide member to exert the constant radial force on the inner wall (301a) so as to guide the second tubular structure (301) into substantial axial alignment with the first tubular structure (200).

24. Use of a tool according to any one of claims 1 to 20 in a method according to claim 22 or 23.

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