WO2023126038A1

WO2023126038A1 - Tower crane for partially erecting a wind turbine and method of using same

Info

Publication number: WO2023126038A1
Application number: PCT/DK2022/050263
Authority: WO
Inventors: Torben Ladegaard Baun; Peter NORDLYNG
Original assignee: Vestas Wind Systems A/S
Priority date: 2021-12-30
Filing date: 2022-12-06
Publication date: 2023-07-06

Abstract

A crane (38) for partially erecting a wind turbine (10) having a tower (12) formed from vertically segmented tower sections (22) and a nacelle (14). The crane (38) includes a central hub (40), a work platform (42) connected to the central hub (40), the work platform (42) having at least one lifting device (178) for assembling the wind turbine tower (12), and a plurality of telescopic legs (44) disposed about a periphery of the central hub (40). Each of the plurality of telescopic legs (44) includes a first end connected to the central hub (40) and a second end having a claw (80) configured to be connected to a wind turbine tower portion (82). Each of the plurality of telescopic legs (44) is movable between a retracted position and an extended position. A method of partially erecting a wind turbine (10) using the crane (38) is also disclosed.

Description

TOWER CRANE FOR PARTIALLY ERECTING A WIND TURBINE AND METHOD OF USING SAME

Technical Field

The invention relates generally to wind turbines, and more particularly to a tower crane for partially erecting a wind turbine, where the crane is configured to climb the tower as the tower is being assembled, and where the crane is at least partially formed from wind turbine components that ultimately form a part of the assembled wind turbine. The invention further relates to methods of using the tower crane to partially erect a wind turbine.

Background

Wind turbines are used to produce electrical energy using a renewable resource and without combusting a fossil fuel. Generally, a wind turbine converts kinetic energy from the wind into electrical power. A horizontal-axis wind turbine includes a tower, a nacelle located at the apex of the tower, and a rotor having a central hub and a plurality of blades coupled to the hub and extending outwardly therefrom. The rotor is supported on a shaft extending from the nacelle, which shaft is either directly or indirectly operatively coupled with a generator which is housed inside the nacelle. Consequently, as wind forces the blades to rotate, electrical energy is produced by the generator.

In conventional wind turbine construction, whether that be for an onshore or an offshore wind turbine, a foundation may be formed and a foundation flange secured to the foundation for connection to the lower end of the wind turbine tower. Modern wind turbine towers extend hundreds of meters into the air and thus are generally provided as a series of tower sections connected in an end-to-end fashion to form the tower. As can be appreciated from the sheer size of modern wind turbines, the parts of the wind turbine, including the tower sections, nacelle, and rotor blades, are transported to the wind turbine installation site as separate parts and assembled at the installation site to form the wind turbine. The tower is typically assembled first by connecting the wind turbine tower sections together and securing the tower to the foundation. Once the tower is constructed, the nacelle, which houses many wind turbine components including the drive train, generator, and other electrical equipment (e.g., transformer, converter, etc.), may be positioned at the top of the tower. Subsequently, the wind turbine blades may be connected to the rotor hub, which may already be connected to the nacelle and positioned at the top of the tower with the positioning of the nacelle. In order to lift the loads presented by the wind turbine components to the heights required for modern wind turbines, a large, high-capacity crane is typically transported to the installation site of the wind turbine. For onshore wind turbines, the installation sites are often in remote areas with rough terrain. Thus, it can be difficult, time consuming and expensive to transport the large crane to installation sites for assembly of the wind turbine. For offshore wind turbines, the large cranes are typically provided as jack-up vessels or other seafaring vessels which must travel out to sea for some distance to reach the wind turbine installation site. Thus, the transportation of the large cranes to wind turbine installation sites are time consuming and expensive. Moreover, in either scenario of installation sites, the large cranes are generally rented during the period of construction from a third-party provider. The rental cost of large, high-capacity cranes, however, is prohibitive and represents a major expense to the overall construction costs of wind turbines. Furthermore, the operation of the large cranes may take specialized personnel that further increases the overall construction costs.

Accordingly, wind turbine manufacturers and operators seek improved equipment and methods for erecting wind turbines that minimize or eliminate the need for a large, high- capacity crane to be rented, transported, and operated at the installation site to achieve the assembly of the wind turbine.

To address these and other drawbacks, and in a first aspect of the invention, a crane for partially erecting a wind turbine is disclosed. The wind turbine includes a tower formed from a plurality of vertically segmented tower sections and a nacelle. The crane includes a central hub having a first end, a second end, and at least one side wall that extends between the first and second ends, the central hub defining a central axis, a work platform connected to the first end of the central hub, wherein the work platform includes at least one lifting device for assembling the wind turbine tower, and a plurality of telescopic legs disposed about a periphery of the central hub. Each of the plurality of telescopic legs includes a first end connected to the at least one side wall of the central hub and a second end having a claw configured to be connected to a wind turbine tower portion. Moreover, each of the plurality of telescopic legs is movable between a retracted position and an extended position.

In one embodiment, each of the plurality of telescopic legs may include a mounting plate removably connected to the at least one side wall of the central hub, and the first end of each of the plurality of telescopic legs may be connected to the mounting plate. For example, the first end of each of the plurality of telescopic legs may include a pivot for pivotally connecting to the at least one side wall of the central hub. Each of the plurality of telescopic legs may further include at least one pivot actuator for controlling an angle of the respective telescopic leg relative to the central axis of the central hub.

In one embodiment, the claw of each of the plurality of telescopic legs may include a support and pair of clamp plates adjustably connected to the support for connecting the telescopic leg to the wind turbine tower portion. The claw of each of the plurality of telescopic legs may include a pivot for pivotally connecting the claw to the second end of the respective telescopic leg.

In one embodiment, in addition to the at least one lifting device, the work platform may further include control equipment for operating the crane, and more particularly the plurality of telescopic legs. In one embodiment, the at least one lifting device may include a lifting yoke configured to be connected to a tower segment and having at least one thruster. The at least one thruster is configured to allow the lifting device to exert control over the position of the load being lifted by the lifting device, such as a tower segment. In an alternative embodiment, the at least one lifting device may include magnetic rollers configured to be attached to the tower segment and further configured to be movably attached to the partially erected tower. In this embodiment, the partially erected tower may be used as a control guide for controlling the position of the tower segment as it is being raised by the at least one lifting device. The magnetic rollers maintain the tower segment in close proximity to the partially erected tower as the tower segment is being raised.

In one embodiment, the crane may further include a bearing assembly disposed between the central hub and the work platform. The bearing assembly is configured to allow the work platform, and the at least one lifting device more particularly, to rotate relative to the central hub about the central axis, and thereby access different portions of the tower as a tower section is being assembled.

In accordance with an embodiment of the invention, the crane may be formed from at least one wind turbine component. For example, in one embodiment, the central hub of the crane may be provided by a portion of the wind turbine tower. More particularly, the portion of the wind turbine tower may include a transition piece having a first portion with a circular cross-sectional profile and a second portion with a polygonal cross-sectional profile. In another embodiment, the work platform of the crane may be provided by at least a partially assembled nacelle of the wind turbine.

In this regard, the at least one lifting device may be provided by an onboard crane of the at least partially assembled nacelle of the wind turbine. Furthermore, the control equipment of the crane may be provided by control equipment in the at least partially assembled nacelle for operating wind turbine components contained in the nacelle. In yet another embodiment, the bearing assembly of the crane may be provided by a yaw assembly of the wind turbine.

In a second aspect of the invention, a partially assembled wind turbine is disclosed. The partially assembled wind turbine includes a foundation, a wind turbine tower portion connected to the foundation, and the crane according to the first aspect connected to the wind turbine tower portion. In one embodiment, the wind turbine tower portion may include a foundation flange on the foundation of the wind turbine. In another embodiment, the wind turbine tower portion may be an upper end of a previously assembled tower section.

In another aspect, a method of partially erecting a wind turbine is disclosed. The wind turbine includes a tower formed from a plurality of vertically segmented tower sections and a nacelle. The method includes providing a wind turbine tower portion connected to a foundation of the wind turbine; providing the crane according to the first aspect; connecting the crane to the wind turbine tower portion; arranging the crane in the extended position; and assembling a tower section from a plurality of tower segments using the at least one lifting device on the work platform. In this embodiment, each of the plurality of tower segments may be connected to the wind turbine tower portion and to at least one adjacent tower segment of the plurality of tower segments that forms the tower section. In accordance with the method, before the assembly of the tower section, the crane is substantially completely supported by the wind turbine tower portion; during the assembly of the tower section, the crane is partially supported by the wind turbine tower portion and partially supported by one or more of the plurality of tower segments; and after assembly of the tower section, the crane is connected to and substantially completely supported by the assembled tower section.

In one embodiment, the method may further include pivoting at least one of the plurality of telescopic legs to adjust an angle the respective telescopic leg forms relative to the central axis during assembly of the tower section. This allows the telescopic legs to accommodate different size tower sections and further allows the telescopic legs to be moved out of the way to provide space for connecting a tower segment to the wind turbine tower portion.

In one embodiment, assembling the tower section from a plurality of tower segments may further include: (i) disconnecting at least one of the plurality of telescopic legs from the wind turbine tower portion; (ii) connecting the at least one lifting device of the crane to one of the plurality of tower segments; (iii) positioning a lower end of the one of the plurality of tower segments adjacent to the wind turbine tower portion; (iv) connecting the lower end of the one of the plurality of tower segments to the wind turbine tower portion; and (v) connecting the claw of the at least one plurality of telescopic legs disconnected from the wind turbine tower portion to an upper end of the one of the plurality of tower segments. In one embodiment, subsequent to step (i) and prior to step (iii) the method may further include moving the at least one plurality of telescopic legs from the extended position to the retracted position. In one embodiment, step (v) may be performed prior to moving the at least one plurality of telescopic legs from the extended position to the retracted position. In yet another embodiment, the method may further include rotating the work platform relative to the central hub to reposition the at least one lifting device relative to the wind turbine tower portion. In another embodiment, the at least one lifting device may include a lifting yoke having the at least one thruster, the lifting yoke configured to connect to the one of the plurality of tower segments, and wherein step (iii) may further include using the at least one thruster on the lifting yoke to position the lower end of the one of the plurality of tower segments adjacent to the wind turbine tower portion. In another embodiment, the at least one lifting device may include magnetic rollers configured to be coupled to one of the plurality of tower segments and further configured to be coupled to the partially erected tower, and wherein step (iii) may further include using the magnetic rollers to position the lower end of the one of the plurality of tower segments adjacent to the wind turbine tower portion.

In one embodiment, the method may further include repeating steps (i)-(v) for each of the remaining plurality of tower segments that form the tower section.

In one embodiment, the method may further include assembling additional tower sections. In this regard, the method may include: (vi) moving the plurality of telescopic legs from the retracted position to the extended position; and (vii) assembling another tower section from a plurality of tower segments using the at least one lifting device on the work platform, wherein each of the plurality of tower segments is connected to the assembled tower section and to at least one adjacent tower segment of the plurality of tower segments that forms the another tower section. In this embodiment, steps (vi) and (vii) may be repeated a plurality of times to form the tower having multiple tower sections connected end-to-end.

Brief Description of the Drawings

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 a general description of the invention given above, and the detailed description given below, serve to explain the invention.

Fig. 1 is a front perspective view of a wind turbine having a segmented wind turbine tower assembled in accordance with an aspect of the invention;

Fig. 1A is a partial front plan view of an upper part of the wind turbine illustrated in Fig. 1;

Fig. 2 is a cross-sectional view of a segmented tower section in the wind turbine tower of Fig. 1 taken along line 2-2;

Fig. 3 illustrates a plurality of tower segments transported to a wind turbine installation site in a shipping container;

Fig. 4 illustrates a crane in accordance with an embodiment of the invention in a retracted position;

Fig. 5 illustrates the crane shown in Fig. 4 in an extended position;

Fig. 6 is a front perspective view of a central hub of the crane shown in Figs. 4 and 5 in accordance with one embodiment of the invention;

Fig. 7 is a cross sectional view of the central hub shown in Fig. 6;

Fig. 8 is a front perspective view of a telescopic leg of the crane shown in Figs. 4 and 5 in accordance with an embodiment of the invention; Fig. 9 is a front plan view of the telescopic leg shown in Fig. 8;

Fig. 10 is a front perspective view of a mounting plate of the telescopic leg shown in Figs. 8 and 9 in accordance with an embodiment of the invention;

Fig. 11 is a rear perspective view of a mounting plate of the telescopic leg shown in Figs. 8 and 9 in accordance with an embodiment of the invention;

Fig. 12 is a front perspective view of a claw of the telescopic leg shown in Figs. 8 and 9 in accordance with an embodiment of the invention;

Fig. 13 is a cross sectional view of the claw shown in Fig. 12;

Fig. 14 is a front plan view of the work platform of the crane shown in Figs. 4 and 5 in accordance with an embodiment of the invention;

Fig. 15 is a front plan view of the crane shown in Figs. 4 and 5 being assembled to a wind turbine tower portion in accordance with an embodiment of the invention;

Fig. 16 is a flowchart of a method for assembling the wind turbine tower from a plurality of tower sections in accordance with an embodiment of the invention;

Fig. 17 is a flowchart of a method for assembling a wind turbine tower section from a plurality of tower segments in accordance with an embodiment of the invention;

Fig. 18 illustrates a lifting yoke for the crane illustrated in Figs. 4 and 5 in accordance with an embodiment of the invention;

Fig. 19 is a schematic cross-sectional view illustrating an alternative method of lifting a tower segment using a lifting device for attachment to the wind turbine tower portion; and

Figs. 20A-20C illustrate a sequence of using the crane to assemble the wind turbine tower section from a plurality of tower segments in accordance with the method illustrated in Fig. 17. Detailed Description

With reference to Fig. 1, a wind turbine 10 includes a tower 12, a nacelle 14 disposed at the apex of the tower 12, and a rotor 16 operatively coupled to a generator (not shown) housed inside the nacelle 14. In addition to the generator, the nacelle 14 may house various components needed to convert wind energy into electrical energy and to operate and optimize the performance of the wind turbine 10. The tower 12 supports the load presented by the nacelle 14, rotor 16, and other wind turbine components housed inside the nacelle 14 and operates to elevate the nacelle 14 and rotor 16 to a height above ground level or sea level, as may be the case, at which air currents having lower turbulence and higher velocity are typically found.

The rotor 16 may include a central rotor hub 18 and a plurality of blades 20 attached to the central hub 18 at locations distributed about the circumference of the central hub 18. In the representative embodiment, the rotor 16 includes three blades 20, however the number may vary. The blades 20, which project radially outward from the central rotor hub 18, are configured to interact with passing air currents to produce rotational forces that cause the central hub 18 to spin about its longitudinal axis. The design, construction, and operation of the blades 20 are familiar to a person having ordinary skill in the art of wind turbine design and may include additional functional aspects to optimize performance. The rotor 16 may be coupled to the gearbox directly or indirectly via a main shaft extending between the rotor hub 18 and the gearbox. The main shaft rotates with the rotor 16 and is supported within the nacelle 14 by a main bearing support which supports the weight of the rotor 16 and transfers the loads on the rotor 16 to the tower 12. The gearbox transfers the rotation of the rotor 16 through a coupling to the generator. Wind exceeding a minimum level may activate the rotor 16, causing the rotor 16 to rotate in a direction substantially perpendicular to the wind, applying torque to the input shaft of the generator to produce electricity.

The wind turbine 10 may be included among a collection of similar wind turbines belonging to a wind farm or wind park that serves as a power generating plant connected by transmission lines with the power grid, such as a three-phase alternating current (AC) power grid. The electrical power produced by the generator may be supplied to a power grid (not shown) or an energy storage system (not shown) for later release to the grid as understood by a person having ordinary skill in the art. The power grid generally consists of a network of power stations, transmission circuits, and substations coupled by a network of transmission lines that transmit the power to loads in the form of end users and other customers of electrical utilities.

As illustrated in Fig. 1 , the wind turbine tower 12 may include a plurality of tower sections 12a stacked one on top of the other and connected at their horizontal ends to collectively form the tower 12. The figure illustrates eight tower sections 12a but the number may be more or less than this value depending on, for example, the height of the tower 12. To accommodate the large bending loads in the tower 12 and to facilitate transportation of the tower sections 12a to the wind turbine installation site, the tower sections 12a may have a segmented design. In this regard, each of the tower sections 12a may be formed by a plurality of tower segments 22 arranged one next to the other and connected at their vertical side edges to collectively form the tower section 12a. In an exemplary embodiment, and as illustrated in Fig. 1, the wind turbine tower 12 may be configured such that each of the tower sections 12a have a segmented design. However, aspects of the invention may prove beneficial to other types of towers, such as hybrid towers (not shown), where the lower tower sections have a segmented design and the upper tower sections have the more conventional tubular design. In any event, aspects of the present invention may be particularly suited to wind turbine towers having at least one segmented tower section, and preferably to wind turbine towers having many segmented tower sections.

Fig. 2 illustrates a cross-sectional view of one of the segmented tower sections 12a. As illustrated in this figure, in an exemplary embodiment, the tower section 12a may be formed from eight tower segments 22 that are joined along vertical side edges 24a, 24b to the vertical side edges 24b, 24a, respectively, of adjacent tower segments 22. While Fig. 2 illustrates the tower section 12a being formed from eight tower segments 22, it should be understood that the number of tower segments 22 in the tower section 12a may be more or less than this value in alternative embodiments. When the plurality of tower segments 22 are joined together along their respective vertical side edges 24a, 24b, the tower section 12a may have a polygonal cross-sectional profile. This is in contrast to traditional tower sections, which typically have circular cross-sectional profiles. By way of example and without limitation, in one embodiment (not shown), each tower segment 22 may be generally planar and configured such that each tower segment forms one side of the polygonal cross section. In another embodiment, however, each tower segment 22 may be generally non-planar and include two or more generally planar bent panels 26 formed about one or more generally vertical bend lines 28 in the tower segment 22. In one embodiment, each tower segment 22 may include four panels 26 formed about three bend lines 26. For example, in the embodiment shown in Fig. 2, the segmented tower section 12a has a twenty-four-sided polygonal cross-sectional profile. It should be recognized, however, that the number of bend lines 28 and panels 26 in a tower segment 22 may vary to provide a polygonal cross-sectional profile with the desired number of sides. Thus, the invention should not be limited to the particular embodiment shown and described herein.

As noted above, one of the benefits of a segmented tower section 12a is that the tower section may be transported to a wind turbine installation site 30 (see Fig. 1) as separate parts and then assembled on site to form the tower section 12a. In an exemplary embodiment, and as illustrated in Fig. 3, the length of the tower segments 22 may be selected such that the tower section 12a may be transported to the wind turbine installation site 30 in one or more shipping containers 32. In this regard, a plurality of tower segments 22 may be arranged in a vertical stack 34 (e.g., four or more high) and loaded into the one or more shipping containers 32 for transport to the installation site 30. By way of example and without limitation, the segmented tower section 12a may require two shipping containers 32, with each container 32 carrying a stack of four of the eight tower segments 22. Those of ordinary skill in the art will understand how to arrange the tower segments 22 in a stack 34, and how to load the stacks 34 into their respective shipping containers 32. Those of ordinary skill in the art will further understand how to remove the stacks 34 of tower segments 22 from the shipping containers 32 once they arrive at the wind turbine installation site 30. Accordingly, for sake of brevity a more detailed description of these steps will not be provided herein. It should be understood that the above is merely exemplary and that in other embodiments, the length of the tower segments 22 may be less than or greater than that of a shipping container 32 and transported to an installation site 30 by truck, rail, or other means known to those of ordinary skill in the art. Thus, aspects of the invention should not be limited to the transport of the tower segments 22 or other wind turbine components to the installation site 30 via shipping containers.

Figs. 4 and 5 illustrate a crane 38 in accordance with an embodiment of the invention for partially assembling the wind turbine 10 shown, for example, in Fig. 1. The crane 38 is configured to have a collapsed or retracted position (Fig. 4) and an extended position (Fig. 5) and generally includes a central hub 40, a work platform 42 connected to the central hub 40, and a plurality of telescopic legs 44 connected to and disposed about the periphery of the central hub 40 in spaced-apart relation. The crane 38 is significantly different from the large, high-capacity cranes typically used to assemble wind turbines. In this regard, and as explained in more detail below, the crane 38 is configured to have a tower-crawling design so that the crane 38 can progressively move up the tower 12 as the tower 12 is being assembled from the multiple tower sections 12a. In other words, the crane 38 is not supported by the ground (onshore) or platform or deck of a ship (offshore) but is supported by the tower itself (e.g., at least a portion thereof) during the use of the crane 38. Such a tower-crawling crane 38 may provide a number of benefits to wind turbine assembly.

In this regard, the crane 38 may minimize or eliminate the need to have the large, high- capacity crane at the wind turbine installation site 30. For example, the crane 38 may be used to assemble only part of the wind turbine 10 while the large, high-capacity crane may still be required at the installation site 30 to assemble other parts of the wind turbine 10. In one embodiment, for example, the crane 38 may be used to assemble the tower 12, but the large crane used to assemble the nacelle 14 to the tower 12 and the wind turbine blades 20 to the rotor hub 18. In a second embodiment, the crane 38 may be used to assemble both the tower 12 and the nacelle 14, but the large crane used to assemble the wind turbine blades 20 to the rotor hub 18. In either embodiment, however, the amount of time the large crane is used at the installation site 30 may be significantly reduced, which reduces the rental and operating costs of the large crane. In some embodiments, the crane 38 may be used to assemble the tower 12 and the nacelle 14, and another blade lifting arrangement (not shown but generally known to those of ordinary skill in the art) may be used to assemble the wind turbine blades 20 to the rotor hub 18. Thus, in these embodiments, there is no requirement to have the large, high-capacity crane at the wind turbine installation site 30 at all. Accordingly, the costs associated with the transport, rental, and operation of the large crane may be completely avoided in the construction of the wind turbine 10.

The crane 38 may be significantly different from the large, high-capacity cranes typically used to assemble wind turbines in another way. In this regard, and as further explained below, one or more components of the crane 38 may be provided by one or more components of the wind turbine 10. In other words, certain wind turbine components that ultimately form a part of the wind turbine 10, such as a permanent part of the wind turbine 10, may have a dual role, in which those wind turbine components also operate as components of the crane 38 for its structure and/or function. By way of example, in one embodiment, the work platform 42 of the crane 38 may be provided by the nacelle 14 for the wind turbine 10. In a second embodiment, the central hub 40 of the crane 38 may be provided by a portion of the wind turbine tower 12 (e.g., such as a transition piece of the tower, as discussed below). The dual use of some wind turbine components as crane components may provide additional benefits. For example, the number of components that need to be transported to the wind turbine installation site for wind turbine construction is reduced. More particularly, as will be appreciated later, the number of components used for the crane 38 that do not also operate as a permanent part of the wind turbine 10 may be relatively few. Thus, by transporting the wind turbine components to the installation site 30, which is required to construct the wind turbine 10, a substantial portion of the crane 38 has also been transported to the installation site 30. Moreover, any remaining components of the crane 38 not already transported to the installation site 30 by transport of the wind turbine components, may be relatively compact. Thus, these remaining crane components may be transported to the installation site 30 easily and at relatively low cost.

Furthermore, and somewhat related to the above, using wind turbine components as crane components minimizes the need to have the large, high-capacity crane at the installation site. For example, in this embodiment, after the uppermost tower section 12a has been assembled to form the tower 12, the crane 38 is already positioned at the top of the tower 12 due to the tower-crawling configuration of the crane 38. Thus, the nacelle 14, operating as the work platform of the crane 38, and the transition piece of the tower 12, operating as the central hub 40 of the crane 38, are already positioned at the top of the tower 12 and may be connected to the top of the tower 12 in a straight-forward manner. Accordingly, there is no need for the large crane to position the nacelle 14 and the transition piece of the tower 12 at the top of the tower 12 because these components are already there from their use as part of the crane 38. Thus, the crane 38 can not only be used to assemble the tower 12 but may also locate the transition piece, nacelle 14, and other wind turbine components at the top of the tower 12. This will be made clear from the description below.

Turning now to the details of the crane 38, and as illustrated in Figs. 6 and 7, the central hub 40 may be generally tubular and include a first upper end 46, a second lower end 48, and at least one side wall 50 extending between the upper and lower ends 46, 48. The central hub 40 defines a central axis 52 and the at least one side wall 50 defines an inner surface 54 and an outer surface 56 of the central hub 40. The upper end 46 of the central hub 40 may include a connection flange 58 configured to connect the central hub 40 to the work platform 42 that forms part of the crane 38 and facilitates the crane's ability to assemble portions of the wind turbine 10. In one embodiment, the central hub 40 may include a hub platform 60 (shown in phantom in Fig. 7) attached to the inner surface 54 of the central hub 40 adjacent the upper end 46. The hub platform 60 may be configured to hold personnel (e.g., assembly or service technicians) for connecting the work platform 42 to the upper end 46 of the central hub 40 and for performing other assembly tasks. For example, assembly technicians may apply fasteners (e.g., nuts/bolts) to secure the work platform 42 to the upper end 46 of the central hub 40.

As illustrated in these figures, the plurality of telescopic legs 44 is releasably connected to the outer surface 56 of the central hub 40. In one embodiment, the telescopic legs 44 are uniformly spaced about the periphery of the central hub 40. The invention, however, is not limited to this arrangement and a non-uniform distribution of the telescopic legs 44 about the periphery of the central hub 40 may also be possible. In one embodiment, the location where each of the telescopic legs 44 connects to the outer surface 56 of the central hub 40 may be at the same position (e.g., vertical position) between the upper and lower ends 46, 48 of the central hub 40, such as illustrated in the figures. In a second embodiment (not shown), however, the location where each of the telescopic legs 44 connects to the outer surface 56 of the central hub 40 may be at different positions between the upper and lower ends 46, 48 of the central hub 40. Still further, in one embodiment, the location where each of the telescopic legs 44 connects to the outer surface 56 of the central hub 40 may be closer to the upper end 46 of the central hub 40 than to the lower end 48 of the central hub 40. More particularly, in an exemplary embodiment, the location where each of the telescopic legs 44 connects to the outer surface 56 of the central hub 40 may be closer to the upper end 46 of the central hub 56 than the hub platform 60 (i.e. , the hub platform 60 is positioned below where each of the telescopic legs 44 connects to the central hub 40). This will allow, for example, assembly technicians stationed on the hub platform 60 to facilitate the connection between the plurality of telescopic legs 44 and the central hub 40 using fasteners, such as nuts and bolts.

As noted above, in one embodiment, the central hub 40 of the crane 38 may be provided by a portion of the wind turbine tower 12. More particularly, the central hub 40 may be provided by a transition piece 68 of the wind turbine tower 12. With reference to Figs. 1 and 1A, the tower 12 is constructed from a plurality of tower sections 12a connected end- to-end where the tower sections 12a include a polygonal cross-sectional profile similar to that shown in Fig. 2 and described above. However, to allow the nacelle 14 to yaw relative to the tower 12, the lowermost portion of the nacelle 14 typically includes a yaw assembly 62 (shown schematically in Fig. 1A). As is readily understood by those of ordinary skill in the wind turbine industry, the yaw assembly 62 typically includes a yaw bearing, a gear, and a plurality of yaw motors. Activation of the yaw motors rotates the nacelle 14 relative to the tower 12. The yaw assembly 62 is generally circular in its cross- sectional profile. Accordingly, there is a mismatch in the geometry between the upper end of the tower 12 and the lower end of the nacelle 14. To cure this mismatch in geometry, the transition piece 68 may be disposed between the upper end of the uppermost tower section 12a and the lower end of the nacelle 14 having the yaw assembly 62.

As illustrated in Figs. 6 and 7, in an exemplary embodiment, the transition piece 68 includes an upper portion 70 having a circular cross-sectional profile and a lower portion 72 having a polygonal cross-sectional profile. The upper portion 70 of the transition piece 68 defines the upper end 46 of the central hub 40 which may be sized to match the size of the lower end of the nacelle 14. As noted above, the upper end 46 of the transition piece 68 may include the connection flange 58 for connecting to the work platform 42. As explained below, this same connection flange 58 may also be coupled to the lower end of the nacelle 14. The lower portion 72 of the transition piece 68 defines the lower end 48 of the central hub 40 which may be sized to match the size of the upper end of the uppermost tower section 12a. Thus, the transition piece 68 is configured to provide a shape and/or size transition between the upper end of the uppermost tower section 12a and the lower end of the nacelle 14 that allows the connection between the two wind turbine components. In an exemplary embodiment, the telescopic legs 44 may be connected to the transition piece 68 along the upper portion 70 having the circular cross- sectional profile. Locations along the lower portion 72, however, remain possible and within the scope of the present invention.

Figs. 8 and 9 illustrate one of the telescopic legs 44 in accordance with an embodiment of the invention. Each of the telescopic legs 44 has a similar construction and a description of one of the telescopic legs 44 is believed sufficient for an understanding of the invention. Each telescopic leg 44 includes an actuator 76 movable between a collapsed or retracted position (Fig. 4) and an extended position (Fig. 5), a mounting plate 78 for attaching the actuator 76 to the central hub 40, and a claw 80 for connecting the actuator 76 to a wind turbine tower portion 82. The mounting plate 78 may be omitted in some embodiments. As illustrated in Figs. 4 and 5, the plurality of telescopic legs 44 may be operated in unison to move the crane 38 between the retracted and extended positions. It should be noted, however, that the telescopic legs 44 may be moved independently of each other. The number of telescopic legs 44 of the crane 38 may vary depending on the particular application. In one embodiment, for example, the number of telescopic legs 44 of the crane 38 may be between about six and about twelve, however other values outside of this range may be possible. In one embodiment, the number of legs 44 may correspond to the number of tower segments 22 that form a tower section 12a of tower 12. Based on the above description of the tower section 12a, for example, the crane 38 may include eight telescopic legs 44. However, in other embodiments, the number of telescopic legs 44 may be greater than or less than the number of tower segments 22 that form the tower section 12a. For example, two telescopic legs 44 may be associated with each tower segment 22 that forms tower section 12a.

In one embodiment, the actuator 76 includes an actuator body 84 defining a first upper end 86 and a second lower end 88 movable relative to each other between the retracted and extended positions. For example, the actuator body 84 may include a plurality of actuator sections 90 telescopically arranged and movable relative to each other to define the retracted and extended positions. The number of actuator sections 90 that form an actuator 76 may vary between, for example, about three and about ten actuator sections 90. In an exemplary embodiment, the actuator 76 may include five actuator sections 90. The actuator sections 90 include a root actuator section 90a that defines the upper end 86 of the actuator 76 and is configured to be connected to the central hub 40, and a tip actuator section 90b that defines the lower end 88 of the actuator 76 and is configured to be connected to the claw 80 (discussed below).

In the retracted position, the length of the telescopic legs 44 may be relatively small. For example, the telescopic legs 44 may have a length between about 2 meters (m) and about 6 m in the retracted position. More particularly, in an exemplary embodiment, the telescopic legs 44 may have a length of about 4 m in the retracted position. In the extended position, the length of the telescopic legs 44 may be greater and may be between about 10 m and about 30 m. More particularly, in an exemplary embodiment, the length of the telescopic legs 44 may be about 16 m in the extended position. These length ranges and values may vary depending on the particular application, and the invention should not be limited to those provided above. In one embodiment, each of the actuator sections 90 may have a square or rectangular cross-sectional profile. It should be appreciated, however, that the actuator sections 90 may have different cross-sectional profiles, such as circular, oval or other polygonal profiles. In some embodiments, the actuator 76 of the telescopic leg 44 may take the form of a pneumatic or electric actuator. In a preferred embodiment, however, the actuator 76 of the telescopic leg 44 may be configured as a hydraulic actuator, which is relatively simple in its construction and capable of lifting high loads.

As illustrated in the figures, the upper end 86 of the actuator 76 may be connected to the central hub 40 through the mounting plate 78. In one embodiment, and as illustrated in Figs. 10 and 11, the mounting plate 78 may include a generally rectangular base plate 94 and a pair of spaced-apart lugs 96 projecting from the base plate 94 and configured to receive the upper end 86 of the actuator 76 therebetween, as will be explained in more detail below. The base plate 94 includes an inner surface 98 configured to mate against the outer surface 56 of the central hub 40 and an outer surface 100 from which the lugs 96 project. The inner surface 98 may be generally arcuate and correspond to a generally arcuate shape of the outer surface 56 of the central hub 40, such as along the upper portion 70 of the transition piece 68. Moreover, the outer surface 100 between the lugs 96 may include a generally arcuate cut away region 102 configured to create a gap between the outer surface 100 of the base plate 94 and the actuator 76, such as the root actuator section 90a. The lugs 96 are generally parallel to each other and include generally aligned apertures 104 that facilitate a connection between the mounting plate 78 and the actuator 76, as explained below.

The base plate 94 may further include a plurality of fastening holes 106 for connecting the mounting plate 78 to the central hub 40 using suitable fasteners, such as nuts and bolts. In this regard, the fastening holes 106 are configured to be aligned with corresponding fastening holes in the at least one side wall 50 of the central hub 40 (shown in Figs. 6 and 7). Assembly technicians stationed on the hub platform 60 may then apply the fasteners to secure the mounting plate 78 to the outer surface 56 of the central hub 40. Additionally, the base plate 94 may further include one or more control line apertures 108 for routing various control lines to the actuator 76 for operation of the telescopic leg 44. By way of example and without limitation, power lines, hydraulic lines, and/or other control lines may be routed to the actuator 76 through the one or more control line apertures 108 in the mounting plate 78. In one embodiment, the fastening holes 106 and/or the controlline apertures 108 may be positioned within the cut away region 102 of the base plate 94. Other positions, however, may be possible and remain within the scope of the invention. As noted above, the lugs 96 of the mounting plate 78 are configured to receive the actuator 76 therebetween and couple the actuator 76 to the central hub 40 through the mounting plate 78. More particularly, as illustrated in Figs. 8 an 9, the upper end 86 of the actuator 76, which is provided by the root actuator section 90a, may be configured to be coupled to the lugs 96. In an exemplary embodiment, the upper end 86 of the actuator 76 is configured to be movably coupled to the lugs 86, and more specifically pivotally coupled to the lugs 96. In this regard, a pivot pin 110 may extend through the root actuator section 90a and be received within the apertures 104 in the lugs 96 such that the pivot pin 110 defines a pivot about which the actuator 76 may rotate. Thus, the actuator 76 (e.g., a longitudinal axis 112 defined by the actuator 76) may form different angles relative to the central axis 52 of the central hub 40 by rotation about the pivot. In one position (e.g., a zero-angle position), the actuator 76 may be contractable/extendable in a direction that is generally parallel to the central axis 52. In another position (a negative-angle position), the actuator 76 may be contractable/extendable in a direction that generally converges toward the central axis 52. In still another position (a positive-angle position), the actuator 76 may be contractable/extendable in a direction that generally diverges away from the central axis 52. By way of example, and without limitation, the actuators 76 may be able to pivot relative to the central axis 52 of the central hub 40 through an angle between about -30 degrees to about +60 degrees, but other angle ranges are also possible. The cut away region 102 in the base plate 94 of the mounting plate 78 facilitates the pivotal movement of the actuator 76 by providing sufficient space between the actuator 76 and the mounting plate 78. As is generally known, wind turbine towers often have a conical or tapered configuration (e.g., a decreasing diameter in a direction from the bottom of the tower toward the top of the tower). The ability of the telescopic legs 44 to rotate about the pivot allows the crane 38 to accommodate different sized tower sections 12a, i.e., large tower sections 12a near the bottom of the tower 12 and smaller tower sections 12a near the top of the tower 12. The ability of the telescopic legs 44 to rotate also allows the legs 44 to be moved out of the way during assembly of the tower sections 12a, as will be discussed below.

As illustrated in Figs. 8 and 9, to control the movement of the telescopic legs 44 relative to the central hub 40 (i.e., the angle the actuators 76 make relative to the central axis 52 of the central hub 40), each of the telescopic legs 44 may further include at least one control member connected between the central hub 40, and more preferably the mounting plate 78, and the actuator 76. In some embodiments, the control member may take the form of struts, springs, cables, or other elements capable of tension and/or compression for imposing a force on the actuator 76 to alter its position relative to the central axis 52. In one embodiment, for example, the control member may include a controllable pivot actuator 116, such as a pneumatic or electric pivot actuator. In a preferred embodiment, however, the control member may include a hydraulic pivot actuator 116 having a cylinder 118 pivotally connected to the mounting plate 78, and a piston rod 120 connected to a piston in the cylinder 118 and extending from the cylinder 118. The piston rod 120 may be pivotally connected to the actuator 76. In this regard, the mounting plate 78 may include a pair of connecting lugs 122 for pivotally connecting the cylinder 118 of the pivot actuator 116 to the mounting plate 78 and the root actuator section 90a may include a post 124 for pivotally connecting the piston rod 120 of the pivot actuator 116 to the actuator 76. While one pivot actuator 116 may be sufficient, in an exemplary embodiment, two pivot actuators 116 may be provided, one on each side of the actuator 76 for controlling the pivot angle of the telescopic legs 44 relative to the central axis 52 of the central hub 40. It should be appreciated that the control lines for operating the pivot actuators 116 (e.g., electric lines, hydraulic lines, etc.) may also be routed through the control line aperture 108 in the mounting plate 78.

As noted above, each of the telescopic legs 44 includes a claw 80 configured to connect the crane 38 to the wind turbine tower portion 82. As further noted above, the claw 80 may be located at the lower end 88 of the actuator 76 provided by the tip actuator section 90b. In an exemplary embodiment, and as illustrated in Figs. 12 and 13, the claw 80 includes a T-shaped support 128 and a pair of clamp plates 130 moveably connected to the support 128. The T-shaped support 128 includes a generally rectangular base plate 132 and a divider plate 134 fixed to and extending from a central region of a bottom surface of the base plate 132 in a generally perpendicular manner. A pair of spaced-apart lugs 138 project from an upper surface of the base plate 132 to provide a connection to the lower end 88 of the actuator 76. The lugs 138 are generally parallel to each other and include generally aligned apertures 142 that facilitate a connection between the claw 80 and the lower end 88 of the actuator 76. The divider plate 134 includes a plurality of fastening holes 144 for connecting the claw 80 to the wind turbine tower portion 82 or tower segments 22, as explained below.

Clamp plates 130 are positioned on opposing sides of the divider plate 134 to define a gap 146 between the divider plate 134 and each of the clamp plates 130. In one embodiment, the clamp plates 130 are movably connected to the base plate 132 such that the clamp plates 130 can move toward or away from the divider plate 134 and thereby adjust the size of the gap 146 therebetween. In this regard, an upper edge of each of the clamp plates 130 includes one or more threaded bores 150 and the base plate 132 includes a corresponding number of elongate slots 152 which extend in a direction of movement of the clamp plates 130 toward and away from the divider plate 134. A threaded connection pin 154 extends through the elongate slots 152 and into the threaded bores 150 in the clamp plates 130. This provides a secure connection between the clamp plates 130 and the base plate 132 but allows the position of the clamp plates 130 to be adjusted relative to the divider plate 134 to adjust the size of the gaps 146. Each of the clamp plates 130 includes a plurality of fastening holes 158 that are configured to align with the fastening holes 144 in the divider plate 134. In this way, a plurality of connection pins 160 may extend through each of the clamp plates 130 and the divider plate 134 to thereby secure the claw 80 to the wind turbine tower portion 82.

In one embodiment, the claws 80 may be movably connected to the lower end 88 of the actuators 76 that form the telescopic legs 44. More particularly, in an exemplary embodiment, the claws 80 may be pivotally connected to the lower ends 88 of the actuators 76 that form the telescopic legs 44. In this regard, the lower end 88 of the actuator 76 may include a mount 162 having a base plate 164 and a pair of lugs 166 projecting from a lower surface of the base plate 164. The lugs 166 are generally parallel to each other and include generally aligned apertures 170 that facilitate a connection between the claw 80 and the mount 162. To this end, the lugs 138 of the claw 80 and the lugs 166 of the mount 162 may be arranged such that the respective apertures 142, 170 are generally aligned (e.g., a double clevis arrangement). A pivot pin 172 may then be received in the apertures 142, 170 such that the pivot pin 172 defines a pivot about which the claw 80 may rotate. The pivot pin 172 may be oriented such that the claw 80 may generally move toward and away from the central axis 52 of the central hub 54. In one embodiment, for example, the rotational axis defined by the pivot pin 172 may be substantially perpendicular to the longitudinal axis 112 defined by the actuator 76. Other orientations, however, may be possible in various alternative embodiments. Unlike the pivotal connection between the actuators 76 and the central hub 40, however, there may be no control member (e.g., pivot actuator or the like) that controls the pivotal movement of the claw 80. Instead, the claws 80 are free to rotate about the pivot pin 172 as needed to make a connection with the wind turbine tower portion 82 or tower segment 22. This allows assembly technicians, for example, to freely place the claws 80 for connection to the wind turbine tower portion 82 or tower segment 22, as will be explained in more detail below.

As illustrated in Fig. 14, and as discussed above, in an exemplary embodiment, the crane 38 further includes a work platform 42 that carries the equipment necessary to operate the crane 38 and assemble the wind turbine 10, including the wind turbine tower 12. The term work platform means any platform, framework, housing or other structural member that may be connected to the central hub 40, such as at the upper end 46 thereof, and carry equipment necessary to operate the crane 38 and assemble the wind turbine 10. By way of example and without limitation, the work platform 42 may be configured to carry at least one lifting device 178 capable of lifting wind turbine components, such as wind turbine tower segments 22, to assemble the wind turbine tower 12. In an exemplary embodiment, the work platform 42 may be configured to carry two lifting devices 178, but the number may vary. The at least one lifting device 178 may include various winch/cable systems or even small-capacity cranes (with rotatable booms, etc.) capable of lifting the wind turbine components. As can be appreciated, the at least one lifting device 178 may be much smaller than the large, high-capacity crane and have a much smaller lifting capacity. As can be further appreciated, the transport of the work platform 42 and the at least one lifting device 178 to the installation site 30 may be much easier and less costly than transporting the large, high-capacity crane to the installation site 30.

A lower end of the work platform 42 is configured to be connected to the upper end 46 of the central hub 40, such as via the connection flange 58, using suitable fasteners (e.g., nuts and bolts). In an exemplary embodiment, the work platform 42 may be configured to be movably connected to the central hub 40. For example, in one embodiment, the work platform 42 may be rotatably connected to the central hub 40 such that the work platform 42 may rotate about the central axis 52. As will be explained in more detail below, this allows the at least one lifting device 178 on the work platform 42 to access different peripheral regions of the wind turbine tower 12 during assembly. This may be particularly beneficial given the segmented nature of the wind turbine tower sections 12a. In this regard, the lower end of the work platform 42 may include a bearing assembly 182 that permits the relative rotation between the work platform 42 and the central hub 40. The work platform 42 may further include one or more motors (not shown) either part of the bearing assembly 182 or separate therefrom for controlling the rotational movements of the work platform 42 relative to the central hub 40. In one embodiment, the work platform 42 may further include control equipment 184 configured to be operatively coupled to the plurality of telescopic legs 44 for controlling the operation of the crane 38. By way of example and without limitation, the control equipment 184 on the work platform 42 may include various power sources 186, fluid reservoirs 188, pumps 190, and controllers 192. For example, the power sources 186 may include batteries or portable generators capable of providing the electrical energy necessary to operate the crane 38. The fluid reservoirs 188 may include a tank containing hydraulic fluid, and the pumps 190 may include pumps for moving and pressurizing the hydraulic fluid. It should be understood that other control equipment 184 may also be included with the work platform 42 that provides for operation of the crane 38. The control equipment 184 may be coupled to the telescopic legs 44 by routing control lines from the work platform 42, into the central hub 40, and to the telescopic legs 44 through the control line apertures 108 in the mounting plates 78.

As noted above, in an exemplary embodiment, the work platform 42 of the crane 38 may be provided by the nacelle 14 of the wind turbine 10. As readily understood, the nacelle 14 includes a housing 194 that contains many wind turbine components, including the rotor bearing housing, drive train (e.g., gearbox), generator, and electrical equipment (e.g., transformer, converter, etc.). In one embodiment, the nacelle housing 194 may be of a conventional design with a single housing having outer panels connected to an interior framework. In a second embodiment, however, the nacelle 14 may have a unitized architecture including a plurality of separable units 196 (e.g., containers) that are connected together to form the overall nacelle housing 194. No matter the particular configuration, the nacelle 14 may be configured to include the at least one lifting device 178. For example, in one embodiment, the at least one lifting device 178 may include an onboard crane that is a temporary or permanent part of the nacelle 14 of the wind turbine 10. Such onboard cranes are generally known in the wind turbine industry and thus a further description of such cranes will not be provided herein. In another embodiment, the at least one lifting device 178 may include winch/cable systems that are a temporary or permanent part of the nacelle 14 of the wind turbine 10. Thus, it should be appreciated that the lifting devices that typically accompany the nacelle 14 may operate as the lifting devices 178 for the crane 38.

Moreover, as noted above, the lower end of the work platform 42 may include the bearing assembly 182 that provides rotational movement of the work platform 42 relative to the central hub 40. In the embodiment where the nacelle 14 operates as the work platform 42 for the crane 38, the yaw assembly 62 at the lower end of the nacelle 14 may operate as the bearing assembly 182 and may be configured to be connected to the connection flange 58 at the upper end 46 of the central hub 40 during operation of the crane 38. As can be appreciated, the lower end of the nacelle 14 may also be configured to be connected to the upper end of the uppermost wind turbine tower section 12a. For example, in one embodiment, the lower end of the nacelle 14 may be connected to the upper end of the uppermost tower section 12a via the transition piece 68, which as described above, may operate as the central hub 40 of the crane 38. In any event, in this embodiment, it should be appreciated that the yaw assembly 62 of the nacelle 14 may operate as the bearing assembly 182 of the crane 38.

Furthermore, at least some of the control equipment 184 used to operate the crane 38, such as the telescopic legs 44, may be provided by the wind turbine components that are typically housed in the nacelle 14. For example, the nacelle 14 may include a hydraulic system (including a fluid reservoir and pumps) for operating the wind turbine components contained in the nacelle 14 (e.g., the gearbox of the drive train) during operation of the wind turbine 10. In accordance with an embodiment of the invention, that hydraulic system may also be used to operate the telescopic legs 44 during operation of the crane 38. Additionally, the nacelle 14 may include one or more backup generators that may be used as a power source to provide electrical power to the crane 38. The nacelle 14 may also include one or more controllers, etc. that control the operation of the wind turbine 10 during use. One or more of these controllers may operate as the controller 192 for operating the crane 38. Accordingly, in this embodiment, it should be appreciated that the control equipment for the wind turbine 10 may operate as the control equipment 184 for the crane 38.

In the exemplary embodiment, it should be clear that by transporting the wind turbine components to the installation site 30, a substantial portion of the crane 38 has also been transported to the installation site 30. More particularly, with the central hub 40 and the work platform 42 of the crane 38 being provided by the transition piece 68 of the wind turbine tower 12 and the nacelle 14 of the wind turbine 10, respectively, and with the yaw assembly 62 and various control equipment of the nacelle 14 also providing the bearing assembly 182 and control equipment 184 of the crane 38, the plurality of telescopic legs 44 may be nearly the only portion of the crane 38 that does not form a permanent part of the wind turbine 10 after assembly. The plurality of telescopic legs 44, however, may be easily transported to the installation site 30 and easily connected to the transition piece 68 of the wind turbine tower 12 to assemble the crane 38 and initiate assembly of the wind turbine 10, which will now be described.

As noted above, and as illustrated in Fig. 15, a foundation 200 may be formed at a wind turbine installation site 30 to support the wind turbine 10. The foundation 200 may be in the form of an anchor cage positioned in the ground for onshore wind turbines, for example, or a pile or other foundational element positioned in a body of water for offshore wind turbines. The forming of suitable foundations 200 are generally known in the wind turbine industry and a further discussion will be omitted for sake of brevity. The foundation 200 includes a surface or platform to which a foundation flange 202 may be connected. The foundation flange 202 is configured to secure the lowermost tower section 12a (and thus the tower 12 as a whole) to the foundation 200. In one embodiment, the crane 38 may be used to assemble the wind turbine tower 12 starting from the foundation flange 202. Thus, in this embodiment, the foundation flange 202 provides the wind turbine tower portion 82, as mentioned above, to which the crane 38 may be initially connected. As can be appreciated, however, the use of crane 38 to assemble the wind turbine 10 does not have to be initiated from the foundation flange 202. For example, in one embodiment, the tower 12 may include a transition piece (not shown) which is connected to the foundation 200 or foundation flange 202. Furthermore, in a second embodiment, the tower 12 may include the lowermost tower section 12a connected to the foundation 200 or foundation flange 202 before use of the crane 38 is initiated to assemble the wind turbine 10. For example, perhaps a small land or seabased crane is used to assemble the lowermost tower section 12a due to its close proximity to the ground, platform or deck. In any event, those tower portions to which the crane 38 is initially attached to assemble the wind turbine 10 may be referred to as the wind turbine tower portion 82. Thus, while the method of assembling the wind turbine 10 using the crane 38 will be described as starting from the foundation flange 202, it should be appreciated that the method may be initiated from other tower portions and remain within the scope of the present invention.

Fig. 16 illustrates a flow chart providing a method 210 of assembling the wind turbine 10 in accordance with an exemplary embodiment of the invention. In a first step 212, the crane 38 may be transported to the wind turbine installation site 30 and assembled there for use to assemble the wind turbine 10. To this end, most, if not all, of the components of the crane 38, whether in the form of wind turbine components of not, may be transported to the installation site 30 in its various parts. For example, many of the crane components may be transported to the installation site 30 in one or more shipping containers, similar to the container(s) 32 described above for transporting the tower segments 22. Once on site, the crane components may be assembled to form the crane 38. For example, the telescopic legs 44 may be attached to the outer surface 56 of the central hub 40, such as by assembly technicians on the hub platform 60. Moreover, the work platform 42 may be coupled to the upper end 46 of the central hub 40, such as via the connection flange 58. The assembly technicians on the hub platform 60 may also make this connection. The telescopic legs 44 of the crane 38 may initially be in their retracted positions. The assembly technicians may further operatively couple the control equipment 184 on the work platform 42 to the telescopic legs 44 so that the crane 38 is operational.

In a next step 214, the crane 38 may be connected to the wind turbine tower portion 82, which is initially provided in this embodiment by the foundation flange 202. In this step, for example, the claws 80 at the second ends 88 of the telescopic legs 44 may be connected to the foundation flange 202 using connection pins 160, or other suitable fasteners. In regard to steps 212 and 214, and in one embodiment, the assembly of the crane 38 may occur on an assembly stand (not shown) adjacent the foundation 200, such as on the ground or the deck of a ship, and the assembled crane 38 hoisted atop the foundation 200 by a relatively small land or sea-based crane (i.e., significantly smaller than the large, high-capacity cranes) so that the claws 80 of the telescopic legs 44 may be connected to the foundation flange 202. In a second embodiment, however, the central hub 40 and the telescopic legs 44 may be assembled on an assembly stand (not shown) adjacent the foundation 200, that subassembly hoisted atop the foundation 200 by a relatively small land or sea-based crane so that the claws 80 may be connected to the foundation flange 202, and then the work platform 42 connected to the upper end 46 of the central hub 40 to further the assembly of the crane 38. Thus, it should be appreciated that the order of the method steps as described herein may be varied but remain within the scope of the present invention. In any event, subsequent to this connection step, the (assembled) crane 38 now sits atop the foundation flange 202 in the retracted position and the entire weight of the crane 38 is being substantially completely supported by the foundation flange 202.

In a next step 216, the crane 38 may be arranged in the extended position. In this step, for example, the actuators 76 of the telescopic legs 44 may be activated using the control equipment 184 on the work platform 42 so as to move the plurality of telescopic legs 44 from their retracted positions to their extended positions. Since the claws 80 are secured to the foundation flange 202, this results in the work platform 42 being raised up so as to be positioned vertically above and spaced from the foundation flange 202 by an amount corresponding to the length of the telescopic legs 44 in their extended position.

In a next step 218, the crane 38 may be used to assemble a wind turbine tower section 12a, such as the lowermost tower section 12a, from a plurality of tower segments 22. Each of the tower segments 22 includes an upper end 226, a lower end 228, and side edges 24. In one embodiment, for example, the tower segments 22 may be assembled to the foundation flange 202 one at a time until the tower section 12a is fully assembled. In a second embodiment, more than one tower segment 22, such as two tower segments 22, may be assembled to the foundation flange 202 at a time (e.g., such as by having multiple lifting devices 178 on the work platform 42). In any event, the lower end 228 of each tower segment 22 may be connected to the foundation flange 202 and the vertical side edges 24 connected to adjacent tower segments 22 to form the tower section 12a. As is generally known to those of ordinary skill in the art in wind turbines, various splice plates may be used to form the horizontal connections and/or vertical connections of tower segments 22 and a further discussion of such splice plates will not be provided herein.

As can be appreciated, during the assembly of the tower section 12a, at least one telescopic leg 44 of the crane 38 (but less than all the legs 44 of the crane 38) has to be disconnected from the foundation flange 202 and moved out of the way so that at least one tower segment 22 may be positioned and secured to the foundation flange 202. Once the at least one tower segment 22 has been attached to the foundation flange 202, then the at least one telescopic leg 44 that had been disconnected may be reattached to the upper end 226 of the at least one tower segment 22 now attached to the foundation flange 202. Thus, during assembly of the tower section 12a, the weight of the crane 38 may be partially supported by the foundation flange 202, through the telescopic legs 44 that remain connected thereto, and partially supported by the assembled at least one tower segment 22, through the at least one telescopic leg 44 that has been connected to the upper end 226 thereof. In a serial manner, such as by ones or twos, the remaining tower segments 22 may be connected to the foundation flange 202 and to adjacent tower segments 22 to complete the assembly of the tower section 12a. After the tower section 12a has been fully assembled, the crane 38 is positioned atop the now assembled tower section 12a in the retracted position and the weight of the crane 38 is being substantially completely supported by the tower section 12a.

Fig. 17 illustrates a flow chart providing a method 300 of assembling the wind turbine tower section 12a in furtherance of step 218 above and in accordance with an exemplary embodiment of the invention. In a first step 302, at least one of the telescopic legs 44 may be disconnected from the wind turbine tower portion 82. In this regard, one or two of the telescopic legs 44, but not all the telescopic legs 44, may be disconnected from the wind turbine tower portion 82 by disconnecting the claws 80 of the at least one telescopic leg 44 from the wind turbine tower portion 82. The number of telescopic legs 44 disconnected in this step may be limited to the number of remaining connected legs 44 being sufficient to adequately support the crane 38 on the tower 12 (i.e. , the crane 38 is stable even under adverse conditions and without all the telescopic legs 44 supporting the crane 38). In one embodiment, the at least one disconnected leg 44 may be moved to the retracted position adjacent the work platform 42. In a second embodiment, however, the at least one disconnected leg 44 may just be positioned adjacent the wind turbine tower portion 82 from which it was disconnected (for reasons clarified below).

In a next step 304, the at least one lifting device 178 on the work platform 42 may be connected to respective tower segments 22. For example, if the tower segments 22 are being assembled one at a time, then only one lifting device 178 on the work platform 42 may be connected to a tower segment 22. Alternatively, if two tower segments 22 are being assembled at a time, then two lifting devices 178 on the work platform 42 may be connected to respective tower segments 22. Upon transport to the installation site 30, the tower segments 22 may be removed from their containers 32 and positioned on the ground, platform, or deck of a ship, such as in a stacked arrangement 34. In one embodiment, upending equipment, including small cranes or the like, may be provided for orienting the tower segments 22 from a generally horizontal position (such as when removed from the shipping container 32) to a generally vertical position. The at least one lifting device 178 on the work platform 42 may include a lifting yoke 250 configured to connect to the tower segment 22 and maintain or position the tower segment in the generally vertical position. By way of example, the lifting yoke 250 may include a gripper (not shown) for gripping the tower segment 22 (e.g., about the side edges 24 of the tower segment 22). Alternatively, the lifting yoke 250 may include one or more magnetic devices, shown schematically at 252, for making a magnetic connection between the tower segment 22 and the lifting yoke 250. Other forms of releasable connections between the tower segment 22 and lifting yoke 250 may also be possible and should not be limited to that shown and described herein.

In a next step 306, the at least one lifting device 178 may be operated so as to position the lower end 228 of the at least one tower segment 22 adjacent to the wind turbine tower portion 82. In order to position the lower end 228 of the at least one tower segment 22 adjacent to the wind turbine tower portion 82, the at least one lifting device 178 on the work platform 42 has to maintain some ability to control the position of the tower segment 22. In this regard, when hoisting the at least one tower segment 22 using the at least one lifting device 178, one or more tag lines may be used to aid in controlling the at least one tower segment 22. Moreover, if the at least one lifting device 178 on the work platform 42 is provided by a small crane, then the crane will have some ability to control the position of the at least one tower segment 22 through the movement of the crane (e.g., its crane boom). However, the at least one lifting device 178 of the work platform 42 may not have the ability to manipulate the position of the at least one tower segment 22. For example, various winch/cable systems, which may constitute the at least one lifting device 178, typically only have the ability to raise the load being carried by the system in a vertical direction and movements in a non-vertical direction are limited or generally not possible. For this type of lifting device 178, and as illustrated in Fig. 18, the lifting yoke 250 may be augmented with one or more thrusters 254 that allow the load being carried by the lifting device 178 (e.g., the at least one tower segment 22) to move in a non-vertical direction, which improves the ability of the lifting device 178 to more precisely locate the lower end 228 of the at least one tower segment 22. The one or more thrusters 254 may be provided in the form of one or more blowers such as propellers or turbines. Alternatively, the one or more thrusters 254 may include one or more rocket motors. The lifting yoke 250 may include a control system 256 including various orientation and position sensors, as well as a thruster control unit, that allows the position of the one or more tower segments 22 being hoisted by the lifting device 178 to be controlled. Such lifting yokes 250 are more fully disclosed in WO 2019/219151, which is owned by the owner of the present disclosure, and thus a more complete description of the lifting yoke 250 will not be provided herein.

In another embodiment, control over the at least one tower segment 22 being hoisted by the at least one lifting device 178 may be achieved in a different manner. For example, in this embodiment, the portion of the tower 12 that is already assembled may be used as a control guide during the hoisting of a tower segment 22 by the at least one lifting device 178. More particularly, the at least one lifting device 178 may include a lifting yoke 250 configured to connect to the tower segment 22 and maintain or position the tower segment 22 in the generally vertical position, similar to that above. However, in this embodiment, and as illustrated in Fig. 19, the at least one lifting device 178 (or the lifting yoke 250) may further include one or more rollers 260 attachable to the tower segment 22 that permit controlled movement along the portion of the tower 12 that has already been assembled. In one embodiment, the one or more rollers 260 may be magnetic rollers that are attracted to the partially assembled tower 12 through magnetism. In one embodiment, the rollers 260 may be separate from the lifting yoke 250 and attachable to the tower segment 22. In an alternative embodiment, however, the rollers 260 may form part of the lifting yoke 250 such that when the lifting yoke 250 is attached to the tower segment 22, the rollers 260 are positioned relative to the tower segment 22 so as to magnetically couple to the partially assembled tower 12. In any event, the at least one lifting device 178 may be configured to position the tower segment 22 near the partially assembled tower 12 such that the rollers 260 may attach or stick to the tower 12, even under windy conditions. In this way, as the tower segment 22 is being hoisted by the at least one lifting device 178 control over the at least one tower segment 22 may be maintained via the rollers 260 and optionally one or more tag lines (not shown), and its lower end 228 may be positioned adjacent the wind turbine tower portion 82, similar to that above. It should be appreciated that this embodiment may be implemented after at least the lowermost tower section 12a has been assembled and connected to the foundation flange 202. The use of the partially assembled tower 12 as a control guide during the hoisting of a tower segment 22 may be more apparently understood for the assembly of the upper tower sections 12a of the tower 12, in which the tower segments 22 are being hoisted significant distances.

In a further step 308, assembly technicians adjacent the wind turbine tower portion 82 (e.g., on the foundation or on a platform of a previously assembled tower section 12a) may use suitable fasteners to connect the lower end 228 of the at least one tower segment 22 to the wind turbine tower portion 82. For example, the lower end 228 of the one or more tower segments 22 and/or the wind turbine tower portion 82 may include splice plates or the like for making a connection between the at least one tower segment 22 and the wind turbine tower portion 82 using suitable fasteners, such as nuts and bolts.

In one embodiment, once the at least one tower segment 22 has been connected to the wind turbine tower portion 82, and in a further step 310, the claw 80 at the lower end 88 of the at least one telescopic leg 44 previously disconnected from the wind turbine tower portion 82 may be reconnected to the upper end 226 of the at least one tower segment 22 that had just been connected to the wind turbine tower portion 82. In this regard, for example, assembly technicians adjacent the wind turbine tower portion 82 may use a portable lift or the like (not shown) to raise one or more assembly technicians adjacent to the work platform 42, and connect the claw 80 (e.g., with the associated telescopic leg 44 in the retracted position) to the upper end 226 of the at least one tower segment 22. In a second embodiment, instead of the assembly technicians being lifted up from the wind turbine tower portion 82, assembly technicians may be lowered from the work platform 42 to connect the claw 80 to the upper end 226 of the at least one tower segment 22. The upper end 226 of the at least one tower segment 22 may include one or more splice plates to which the claw 80 of the at least one retracted telescopic leg 44 may be connected, such as by nuts and bolts. As can be appreciated, the splice plates may be attached to the upper end 226 of the at least one tower segment 22 prior to the tower segment 22 being hoisted by the at least one lifting device 178 (e.g., such as on the ground, platform, deck, or in the factory prior to transporting the tower segments 22 to the installation site 30). In any event, as noted above, during this intermediate assembly of the tower section 12a, the crane 38 is being partially supported by the wind turbine tower portion 82 and partially supported by the one or more tower segments 22 that form the tower section 12a being assembled.

As noted above, in regard to step 302, the at least one telescopic leg 44 disconnected from the wind turbine tower portion 82 may be immediately moved to the retracted position adjacent to the work platform 42 to move the telescopic leg 44 out of the way and create sufficient space for the attachment of the at least one tower segment 22 to the wind turbine tower portion 82. In a second embodiment, however, after disconnecting the claw 80 of the at least one telescopic leg 44 from the wind turbine tower portion 82, the disconnected telescopic leg 44 may remain in the vicinity of the wind turbine tower portion 82. According to this embodiment, the method 300 may further include operating the at least one lifting device 178 on the work platform 42 to position the upper end 226 of the at least one tower segment 22 adjacent the wind turbine tower portion 82. The assembly technicians at the wind turbine tower portion 82 may then connect the claw 80 of the at least one disconnected telescopic leg 44 to the upper end 226 of the at least one tower segment 22 while positioned near the wind turbine tower portion 82. This avoids the assembly technicians from having to be lifted from the wind turbine tower portion 82 or lowered from the work platform 42 to make the connection between the claw 80 and the upper end 226 of the at least one tower segment 22. Additionally, the disconnected telescopic leg 44 may partially aid in the raising of the one or more tower segments 22 in order to locate the lower end 228 of the at least one tower segment 22 adjacent the wind turbine tower portion 82. Furthermore, the at least one telescopic leg 44 connected to the upper end 226 of the at least one tower segment 22 may facilitate additional control over the tower segment 22 during the positioning step 306. Similar to the above, it should be appreciated that this embodiment may be implemented after at least the lowermost tower section 12a has been assembled and connected to the foundation flange 202.

After steps 308 and 310, method 300 may include a decision block 312 to determine if all the tower segments 22 that form the tower section 12a have been assembled to the wind turbine tower portion 82 and to adjacent tower segments 22. If all the tower segments 22 that form the tower section 12a have not been assembled (the N branch), then the method 300 may repeat steps 302-310 until all the tower segments 22 in the tower section 12a have been assembled. Before repeating those steps, however, the method 300 may include the further step 314 of repositioning the work platform 42 relative to the wind turbine tower portion 82 (and relative to the central hub 40 and plurality of legs 44 which are attached thereto). More particularly, to allow the at least one lifting device 178 on the work platform 42 to access other portions of the wind turbine tower 12 for connecting tower segments 22 to the wind turbine tower portion 82, the work platform 42 may be rotated relative to the central hub 40 about the central axis 54 to facilitate that access. In this regard, the bearing assembly 182 at the lower end of the work platform 42 provides for such rotation.

If all the tower segments 22 that form the tower section 12a have been assembled (the Y branch), then the tower section 12a has been assembled using the crane 38 and securely connected to the wind turbine tower portion 82 at the lower end of the tower section 12a. As noted above, upon assembly of the tower section 12a, the crane 38 is positioned atop the assembled tower section 12a, i.e. , the claws 80 of the plurality of telescopic legs 44 are connected to the upper end of the tower section 12a and are in the retracted position. In this position, the weight of the crane 38 is being substantially completely supported by the now assembled tower section 12a. In other words, there is no direct connection between the crane 38 and the wind turbine tower portion 82 to which the crane 38 was previously connected. The description provided above makes clear how the crane 38 "climbs" the tower 12 during assembly of the tower 12. Now that the assembly of a tower section 12a has been described in connection with Fig. 17, the method 210 described in Fig. 16 may now be more fully described. In this regard, in decision block 220, it may be determined if all the tower sections 12a that form the tower 12 have been assembled by the crane 38. If all the tower sections 12a that form the tower 12 have not been assembled (the N branch), then the method 210 may include repeating steps 216 and 218 to assemble any number of wind turbine tower sections 12a on top of the previously assembled tower section 12a. For each additional tower section 12a, the method 300 provided in Fig. 17 may be used to assemble the additional tower section 12a. However, it should be appreciated that the wind turbine tower portion 82 referenced in method 300 is now provided by the upper end of the previously assembled tower section 12a. In other words, the additional tower section 12a is connected to the upper end of the previous tower section 12a in an end-to-end fashion, as is understood in the wind turbine industry. If all the tower sections 12a that form the tower 12 have been assembled (the Y branch), then the tower 12 has been assembled and the crane 38 is positioned atop and connected to the uppermost tower section 12a of the tower 12.

Figs. 20A-20C illustrate a sequence of using the crane 38 to assemble tower segments 22 to form a tower section 12a in accordance with the method outlined above and illustrated in Fig. 17.

As discussed above, in one embodiment, the crane 38 may be used to only assemble the tower sections 12a together to form the tower 12. In accordance with that embodiment, after the tower 12 has been assembled, the crane 38 may be removed from the top of the tower 12. In this regard, the large, high-capacity crane may be used to remove the crane 38, including the work platform 42, central hub 40, and plurality of legs 44, from the top of the tower 12. The large crane may then be used to connect the nacelle 14 to the top of the tower 12 (e.g., with the transition piece 68). The large crane may also be used to attach the wind turbine blades 20 to the rotor hub 18. In this embodiment, while the large crane is still required for assembly of the wind turbine 10, the amount of time the large crane must be at the installation site 30 is reduced due to the assembly of tower 12 with crane 38. Thus, the use of crane 38 in the assembly of the wind turbine 10 remains beneficial in reducing the overall costs of wind turbine assembly.

However, as also discussed above, in a preferred embodiment, several of the wind turbine components that ultimately form a permanent part of the wind turbine 10 may also be used as components of the crane 38 during assembly of the wind turbine 10. As noted above, the transition piece 68 of the tower 12 may operate as the central hub 40 of the crane 38. Perhaps more importantly, however, the nacelle 14 of the wind turbine 10 may operate as the work platform 42 of the crane 38. Moreover, in this embodiment, components typically provided in the nacelle 14 for operation of the wind turbine 10 may further operate as components of the crane 38. For example, the nacelle 14 may include one or more onboard cranes that operate as the at least one lifting device 178 of the work platform 42. The nacelle 14 may also include various equipment and systems, such as power sources, fluid reservoirs, pumps, and controllers, that operate as the control equipment 184 for operating the crane 38. Furthermore, the yaw assembly 62 attached to the nacelle 14 may operate as the bearing assembly 182 of the crane 38. In these embodiments, the method may further include connecting the nacelle 14 to the upper end of the uppermost tower section 12a of the tower 12. More specifically, in an exemplary embodiment, the lower end 48 of the transition piece 68 (which has the nacelle 14 connected to its upper end 46 as the work platform 42) may be connected to the upper end of the uppermost tower section 12a to thereby connect the nacelle 14 to the tower 12.

This may be achieved by slightly modifying the method 300 described above as it pertains to the assembly of the uppermost tower section 12a. More particularly, for the tower segments 22 that form the uppermost tower section 12a, instead of connecting the upper end 226 of the at least one tower segment 22 being positioned by the at least one lifting device 178 to the claw 80 of the disconnected at least one telescopic leg 44, as provided in step 310 described above, the upper end 226 of the at least one tower segment 22 may be connected to the lower end 48 of the transition piece 68, which is operating as the central hub 40 of the crane 38, using splice plates or the like. After all the tower segments 22 that form the uppermost tower section 12a have been assembled, the transition piece 68 and nacelle 14 are connected to and supported by the tower 12. Thus, in this embodiment, it should be appreciated that the crane 38 may be used to assemble both the tower 12 and the nacelle 14 of the wind turbine 10.

In this embodiment, once the nacelle 14 has been connected to the tower 12, the crane 38 may be disassembled. Because some crane components are provided by wind turbine components that do not require removal, dismantling the crane 38 may be relatively easy and take relatively little time. More particularly, since the central hub 40 and the work platform 42 of the crane 38 form a part of the wind turbine 10, dismantling the crane 38 may include removing the plurality of telescopic legs 44 from the transition piece 68 of the assembled wind turbine 10. More particularly, technicians may access the hub platform 60 from the nacelle 14 and remove the fasteners that connect the telescopic legs 44 to the transition piece 68. The onboard crane of the nacelle 14 or a temporary winch system located in the nacelle 14 may then be used to lower the telescopic legs 44 to the ground, platform, deck, etc. The telescopic legs 44 may then be stored in the container they were initially brought in, and subsequently transported to another installation site for use in assembling another wind turbine. It should be appreciated that in a second embodiment, during the assembly of the uppermost tower section 12a, the telescopic legs 44 that are disconnected from the wind turbine tower portion 82 in order to assemble the at least one tower segment 22 may be disassembled immediately after their disconnection in order to create sufficient space for attaching the at least one tower segment 22 at the lower end 228 (i.e. , to the wind turbine tower portion 82) and at the upper end 226 (i.e., to the lower end 48 of the transition piece 68).

Should a large, high-capacity crane be required for further assembly of the wind turbine 10, it may be transported to the installation site 30 for connecting the wind turbine blades 20 to the rotor hub 18. In this embodiment, while the large crane is still required for assembly of the wind turbine 10, the amount of time the large crane must be at the installation site 30 may be significantly reduced due to the assembly of the tower 12 and nacelle 14 with the crane 38. Thus, the use of crane 38 in the assembly of the wind turbine 10 may still prove beneficial in reducing the overall costs of wind turbine assembly.

Lastly, in some embodiments, the wind turbine blades 20 may be connected to the rotor hub 18 without the use of the large, high-capacity crane. For example, the onboard crane of the nacelle 14 and various temporary cranes/lifting devices may be used to connect the wind turbine blades 20 to the rotor hub 18. In this embodiment, the need to have the large crane at the installation site 30 may be completely avoided. Thus, the transportation, rental, and operating costs associated with the large crane may be avoided, thereby reducing the overall costs of wind turbine assembly.

While the present invention has been illustrated by a description of various preferred embodiments and while 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 such detail. Additional advantages and modifications will readily appear to those skilled in the art. Thus, the various features of the invention may be used alone or in any combination depending on the needs and preferences of the user.

Claims

1. A crane (38) for partially erecting a wind turbine (10), the wind turbine (10) including a tower (12) formed from a plurality of vertically segmented tower sections (12a) and a nacelle (14), the crane (38) comprising: a central hub (40) having a first end, a second end, and at least one side wall that extends between the first and second ends, the central hub (40) defining a central axis (52); a work platform (42) connected to the first end of the central hub (40), wherein the work platform (42) includes at least one lifting device (178) for assembling the wind turbine tower (12); and a plurality of telescopic legs (44) disposed about a periphery of the central hub (40), each of the plurality of telescopic legs (44) including a first end connected to the at least one side wall of the central hub (40) and a second end having a claw (80) configured to be connected to a wind turbine tower portion (82), and each of the plurality of telescopic legs (44) being movable between a retracted position and an extended position.

2. The crane (38) of claim 1 , wherein each of the plurality of telescopic legs (44) further comprises a mounting plate (78) removably connected to the at least one side wall of the central hub (40), and wherein the first end of each of the plurality of telescopic legs (44) is connected to the mounting plate (78).

3. The crane (38) of claim 1 or 2, wherein the first end of each of the plurality of telescopic legs (44) includes a pivot for pivotally connecting to the at least one side wall of the central hub (40).

4. The crane (38) of claim 3, wherein each of the plurality of legs (44) further comprises at least one pivot actuator (116) for controlling an angle of the respective telescopic leg (44) relative to the central axis (52) of the central hub (40).

5. The crane (38) of any of the preceding claims, wherein the claw (80) of each of the plurality of telescopic legs (44) includes a pivot for pivotally connecting the claw (80) to the second end of the respective telescopic leg (44).

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6. The crane (38) of any of the preceding claims, wherein the claw (80) of each of the plurality of telescopic legs (44) includes a support (128) and pair of clamp plates (130) adjustably connected to the support (128).

7. The crane (38) of any of the preceding claims, wherein the work platform (42) further includes control equipment (184) for operating the plurality of telescopic legs (44).

8. The crane (38) according to any of the preceding claims, wherein the at least one lifting device (178) includes a lifting yoke (250) configured to be connected to a tower segment (22) and having at least one thruster (254) for controlling a position of the tower segment (22), or wherein the at least one lifting device (178) includes magnetic rollers (260) configured to be movably attached to the tower segment (22) and further configured to be movably attached to the tower (12) for controlling a position of the tower segment (22).

9. The crane (38) of any of the preceding claims, further comprising a bearing assembly (182) disposed between the central hub (40) and the work platform (42), the bearing assembly (182) allowing the work platform (42) to rotate relative to the central hub (40) about the central axis (52).

10. The crane (38) of any of the preceding claims, wherein the crane (38) is formed from at least one wind turbine component.

11. The crane (38) of claim 10, wherein the central hub (40) of the crane (38) is provided by a portion of the wind turbine tower (12).

12. The crane (38) of claim 11 , wherein the portion of the wind turbine tower (12) includes a transition piece (68) having a first portion with a circular cross-sectional profile and a second portion with a polygonal cross-sectional profile.

13. The crane (38) of any of claims 10-12, wherein the work platform (42) of the crane (38) is provided by at least a partially assembled nacelle (14) of the wind turbine (10).

14. The crane (38) of claim 13, wherein the at least one lifting device (178) is provided by an onboard crane of the at least partially assembled nacelle (14) of the wind turbine (10).

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15. The crane (38) of claim 13 or 14, when dependent from claim 7, wherein the control equipment (184) of the crane (38) is provided by control equipment in the at least partially assembled nacelle (14) for operating wind turbine components contained in the nacelle (14).

16. The crane (38) of any of claims 10-15, when dependent from claim 9, wherein the bearing assembly (182) of the crane (38) is provided by a yaw assembly (62) of the wind turbine (10).

17. A partially assembled wind turbine (10), comprising: a foundation (200); a wind turbine tower portion (82) connected to the foundation (200); and the crane (38) according to any of claims 1-16 connected to the wind turbine tower portion (82).

18. The partially assembled wind turbine (10) of claim 17, wherein the wind turbine tower portion (82) includes one of a foundation flange (202) or a tower section (12a).

19. A method of partially erecting a wind turbine (10), the wind turbine (10) including a tower (12) formed from a plurality of vertically segmented tower sections (12a) and a nacelle (14), the method comprising: providing a wind turbine tower portion (82) connected to a foundation (200) of the wind turbine (10); providing the crane (38) according to any of claims 1-16; connecting the crane (38) to the wind turbine tower portion (82); arranging the crane (38) in the extended position; and assembling a tower section (12a) from a plurality of tower segments (22) using the at least one lifting device (178) on the work platform (42), wherein each of the plurality of tower segments (22) is connected to the wind turbine tower portion (82) and to at least one adjacent tower segment (22) of the plurality of tower segments (22) that forms the tower section (12a), wherein before the assembly of the tower section (12a), the crane (38) is substantially completely supported by the wind turbine tower portion (82), wherein during the assembly of the tower section (12a), the crane (38) is partially supported by the wind turbine tower portion (82) and partially supported by one or more of the plurality of tower segments (22), and wherein after assembly of the tower section (12a), the crane (38) is connected to and substantially completely supported by the assembled tower section (12a).

20. The method of claim 19, further comprising pivoting at least one of the plurality of telescopic legs (44) to adjust an angle the respective telescopic leg (44) forms relative to the central axis (52) during assembly of the tower section (12a).

21. The method of claim 19 or 20, wherein assembling the tower section (12a) from a plurality of tower segments (22) further comprises:

(i) disconnecting at least one of the plurality of telescopic legs (44) from the wind turbine tower portion (82);

(ii) connecting the at least one lifting device (178) of the crane (38) to one of the plurality of tower segments (22);

(iii) positioning a lower end of the one of the plurality of tower segments (22) adjacent to the wind turbine tower portion (82);

(iv) connecting the lower end of the one of the plurality of tower segments (22) to the wind turbine tower portion (82); and

(v) connecting the claw (80) of the at least one plurality of telescopic legs (44) disconnected from the wind turbine tower portion (82) to an upper end of the one of the plurality of tower segments (22).

22. The method of claim 21 , wherein subsequent to step (i) and prior to step (iii) the method further comprises moving the at least one plurality of telescopic legs (44) from the extended position to the retracted position.

23. The method of claim 22, wherein step (v) is performed prior to moving the at least one plurality of telescopic legs (44) from the extended position to the retracted position.

24. The method of any of claims 21-23, further comprising rotating the work platform (42) relative to the central hub (40) to reposition the at least one lifting device (178) relative to the wind turbine tower portion (82).

25. The method of any of claims 21-24, wherein the at least one lifting device (178) includes the lifting yoke (250) having the at least one thruster (254), the lifting yoke (250) configured to connect to the one of the plurality of tower segments (22), and wherein step (iii) further comprises using the at least one thruster (254) on the lifting yoke (250) to position the lower end of the one of the plurality of tower segments (22) adjacent to the wind turbine tower portion (82).

26. The method of any of claims 21-25, further comprising repeating steps (i)-(v) for each of the remaining plurality of tower segments (22) that form the tower section (12a).

27. The method of claim 26, further comprising:

(vi) moving the plurality of telescopic legs (44) from the retracted position to the extended position; and

(vii) assembling another tower section (12a) from a plurality of tower segments (22) using the at least one lifting device (178) on the work platform (42), wherein each of the plurality of tower segments (22) is connected to the assembled tower section (12a) and to at least one adjacent tower segment of the plurality of tower segments (22) that forms the another tower section (12a).

28. The method of claim 27, further comprising repeating steps (vi) and (vii) a plurality of times to form the tower (12) comprising multiple tower sections (12a) connected end-to- end.

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