Method for installing a service lift in a multi-part wind turbine tower

Abstract

A method of installing a service lift (22) in a wind turbine tower (12) is provided. The wind turbine tower (12) includes an upper tower portion (32) that is configured to be connected to a lower tower portion (30) to form the wind turbine tower (12). The method includes providing an upper tower stand (36) at a tower pre- assembly site (34) and providing the upper tower stand (36) with the service lift (22). The method includes connecting the upper tower portion (30) of the wind turbine tower (12) to the upper tower stand (36) so that the upper tower portion (30) is supported on the upper tower stand (36), and connecting the service lift (22) in the upper tower stand (36) to the upper tower portion (30) of the wind turbine tower (12) so that the service lift (22) is operational within the upper tower portion (30). The method further includes operating the service lift (22) within the upper tower portion (30) of the wind turbine tower (12) and securing the service lift (22) to the upper tower portion (30) at a location vertically spaced from the upper tower stand (36) for subsequent assembly of the wind turbine tower (12).

Description

[0001] METHOD FOR INSTALLING A SERVICE LIFT IN A MULTI-PART WIND TURBINE TOWER

[0002] Technical Field

[0003] This application relates generally to wind turbines, and more particularly to the installation of a service lift in a wind turbine tower that is assembled from one or more pre-assembled tower portions.

[0004] Background

[0005] 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 plurality of blades and supported in the nacelle by means of a shaft. The shaft couples the rotor either directly or indirectly with a generator, which is housed inside the nacelle. Consequently, as wind forces the blades to rotate, electrical energy is produced by the generator. To this end, wind turbines may be located either on a land mass (onshore) or within a body of water (offshore).

[0006] As the demand for electrical energy has increased in recent years, wind turbines have been developed in larger sizes to generate more electricity. In that regard, offshore wind turbines have gained popularity as they can harness stronger and more consistent wind speeds than onshore turbines, which makes them capable of producing even more electricity. However, the construction and installation of offshore wind turbines, in particular, present several challenges, including the transportation and assembly of large and heavy wind turbine components to a wind turbine site.

[0007] Offshore wind turbines are complex structures, and one of the critical components is the tower, which in some instances can be over 100 meters tall and weigh several hundred tons. Due to their large size and weight, these towers present challenges in terms of pre-assembly, transportation, and installation. Typically, the tower is fully assembled at a pre-assembly site and transported to the offshore site using a seafaring vessel. However, due to limitations such as the weight-bearing capacity of the temporary tower stands at the pre-assembly site, it has become unfeasible to assemble the largest wind turbine towers there. The assembly of towers at a location other than the pre-assembly site has resulted in several challenges. Specifically, the installation of certain tower components like the service lift has become more complicated. In addition, the overall costs of labor and transportation for wind turbine installation have increased. For example, one of the most labor-intensive installation tasks when installing a wind turbine tower is the installation of the tower service lift which is used to transport personnel and parts within the tower during installation, maintenance and service of the wind turbine. To this end, for the largest wind turbine towers described above, a significant portion of the service lift installation tasks may need to be performed at a location other than the pre-assembly site, such as at sea, which further increases installation costs.

[0008] To address the challenges of assembling wind turbine towers at a different location than the pre-assembly site, there is a need for a system and method that utilizes preassembled tower portions to reduce the labor and installation time associated with assembling the wind turbine tower at another location. In that regard, there is a need for preassembled tower portions that can significantly reduce the labor and installation time required to install a service lift within the wind turbine tower at the wind turbine site. By preassembling the tower portions at the pre-assembly site, the service lift installation task can be performed more efficiently at another location, thereby reducing the overall labor and installation time required to assemble the tower for operation. This can lead to cost savings and increased efficiency in wind turbine installation and maintenance.

[0009] Summary

[0010] According to a first aspect of the invention, a method of installing a service lift in a wind turbine tower is disclosed. The wind turbine tower includes an upper tower portion configured to be connected to a lower tower portion to form the wind turbine tower. The method includes providing an upper tower stand at a tower pre-assembly site, providing the upper tower stand with the service lift, positioning the upper tower portion of the wind turbine tower on the upper tower stand so that the upper tower portion is supported on the upper tower stand, and connecting the service lift in the upper tower stand to the upper tower portion of the wind turbine tower so that the service lift is operational within the upper tower portion. The method further includes operating the service lift within the upper tower portion of the wind turbine tower and securing the service lift to the upper tower portion at a location vertically spaced from the upper tower stand for subsequent assembly of the wind turbine tower. For example, operating the service lift within the upper tower portion of the wind turbine tower may include conducting one or more operational tests (e.g., certification testing) to verify proper operation of the service lift.

[0011] According to one embodiment of the invention, the upper tower portion includes a lift wire assembly having a first fixed end attached to the upper tower portion adjacent an upper end thereof and a second free end. In that regard, connecting the service lift in the upper tower portion so as to be operational may include connecting the free end of the lift wire assembly to the upper tower stand and connecting the lift wire assembly to the service lift so that the service lift is moveable along the lift wire assembly.

[0012] In one embodiment, the upper tower stand may include a temporary power supply. In that regard, the method may further include connecting the service lift to the temporary power supply in the upper tower stand so that the service lift is operational within the upper tower portion. For example, connecting the service lift to the temporary power supply may include providing a temporary power cable and connecting the temporary power cable between the temporary power supply and the service lift.

[0013] According to another embodiment of the invention, the upper tower portion of the wind turbine tower includes an upper power cable connected to the upper tower portion. The upper power cable may include a fixed cable portion and a traveling cable portion connected at a cable interface to form the upper power cable. In that regard, the fixed cable portion may include a free end adjacent a lower end of the upper tower portion. The traveling cable portion may include a free end adjacent the lower end of the upper tower portion. In this embodiment, the method may further include connecting the free end of the fixed cable portion to the temporary power supply and connecting the free end of the traveling cable portion to the service lift.

[0014] According to a further embodiment, the upper tower portion may further include a pulley guide wire having a fixed end connected to the upper tower portion and a free end connected to the upper tower stand and a pulley movably attached to the pulley guide wire. As such, connecting the free end of the traveling cable portion to the service lift may further include connecting the free end of the traveling cable portion to the service lift so as to engage the moveable pulley on the pulley guide wire.

[0015] According to one embodiment of the invention, subsequent to securing the service lift to the upper tower portion, the method may include disconnecting the service lift in the upper tower portion from the upper tower stand so that the service lift is non- operational within the upper tower portion. For example, disconnecting the service lift from the upper tower stand may include disconnecting the free end of the lift wire assembly from the upper tower stand.

[0016] In one embodiment, disconnecting the service lift from the upper tower stand may further include disconnecting the service lift from the temporary power supply.

[0017] In another embodiment, disconnecting the service lift from the upper tower stand may include disconnecting the free end of the fixed cable portion of the upper power cable from the temporary power supply.

[0018] In yet another embodiment, disconnecting the service lift from the upper tower stand may include disconnecting the free end of the pulley guide wire from the upper tower stand.

[0019] According to one embodiment, the upper tower portion may include a plurality of tower sections and securing the service lift to the upper tower portion may include securing the service lift to the upper tower portion at an interface between two adjacent tower sections of the plurality of tower sections.

[0020] According to another embodiment of the invention, a lower tower stand at the tower pre-assembly site may be provided. The method may further include positioning the lower tower portion of the wind turbine tower on the lower tower stand so that the lower tower portion is supported on the lower tower stand. The lower tower portion may include a lower power cable connected to the lower tower portion and having a fixed end adjacent a lower end of the lower tower portion for connection to a power supply box mounted to the lower tower portion and a free end adjacent an upper end of the lower tower portion for connection to the upper power cable. The tower preassembly site may be onshore, and preferably quayside.

[0021] A method of assembling a wind turbine tower is disclosed in accordance with a second aspect of the invention. The method includes installing a service lift in the wind turbine tower according the first aspect described above at the tower preassembly site. The method further includes moving the lower tower portion from the tower pre-assembly site to a tower assembly site, moving the upper tower portion from the tower pre-assembly site to the tower assembly site, and connecting the upper tower portion to the lower tower portion to form the wind turbine tower.

[0022] To this end, in one embodiment, the tower assembly site may be aboard a transport vessel, such as an offshore installation vessel.

[0023] According to a third aspect of the invention, a method of installing a wind turbine tower at an offshore wind turbine installation site is disclosed. The method includes assembling the wind turbine tower according to the second aspect described above. The method further includes connecting the wind turbine tower to an offshore foundation, connecting the first fixed end of the lower power cable to the power supply box in the lower tower portion of the wind turbine tower, which may be performed at the tower pre-assembly site, connecting the second free end of the lower power cable to the free end of the fixed cable portion of the upper power cable, connecting the free end of the lift wire assembly to the offshore foundation or the lower portion of the tower, connecting the free end of the pulley guide wire to the offshore foundation, and optionally connecting the free end of the traveling cable traveling portion to the service lift.

[0024] According to one embodiment, the method may further include releasing the service lift from the upper tower portion of the wind turbine tower so as to be operational within the wind turbine tower.

[0025] According to a fourth aspect of the invention, a storage system for a wind turbine tower that includes an upper tower portion and a lower tower portion and a service lift is disclosed. The storage system includes an upper tower stand that supports the upper tower portion of the wind turbine tower and a lower tower stand that supports the lower tower portion of the wind turbine tower. The upper tower portion further includes an upper power cable connected to the upper tower portion. The upper power cable includes a fixed cable portion and a traveling cable portion connected at a cable interface to form the upper power cable. The fixed cable portion includes a free end adjacent the upper tower stand. The upper tower portion further includes a lift wire assembly with a fixed end connected to the upper tower portion adjacent an upper end thereof and a free end adjacent the upper tower stand, and a pulley guide wire with a first end connected to the upper tower portion and a free end adjacent the upper tower stand. The service lift is connected to the upper tower portion at a location vertically spaced from the upper tower stand.

[0026] According to one embodiment of the invention, the lower tower portion may include a lower power cable with a fixed end adjacent the lower tower stand and a free end adjacent an upper end of the lower tower portion. The fixed end of the lower power cable may be connected to or configured to be connected to a power supply box mounted to the lower tower portion.

[0027] According to another embodiment, the upper tower stand may include a temporary power supply.

[0028] In yet another embodiment, the traveling cable portion of the upper power cable may include a free end connected to the service lift.

[0029] In one embodiment, the pulley guide wire may include a pulley movably connected thereto, and the traveling cable portion may be connected to the service lift so as to engage the pulley.

[0030] In another embodiment, the upper tower portion may include a plurality of tower sections, and the service lift may be secured to the upper tower portion at an interface between two adjacent tower sections of the plurality of tower sections. Brief Description of the Drawings

[0031] 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.

[0032] Fig. 1 is a perspective view of a wind turbine according to an embodiment of the invention.

[0033] Fig. 2 is a side view of a lower tower portion and an upper tower portion of a tower of the wind turbine of Fig. 1 arranged at a pre-assembly site.

[0034] Fig. 3 is a view similar to Fig. 2, illustrating a service lift operational within the upper tower portion.

[0035] Fig. 4 is a view similar to Figs. 2 and 3, illustrating the service lift moved to a stowed position within the upper tower portion and disconnected for transportation of the upper tower portion.

[0036] Fig 5 is a side view of the upper tower portion and the lower tower portion connected together at a tower assembly site to form an intermediate assembled tower.

[0037] Fig. 6 is a side view of the tower attached to an offshore foundation at a wind turbine site with the service lift assembled and operational.

[0038] Fig. 7 is a side view of a lower tower portion and an upper tower portion of a tower of the wind turbine of Fig. 1 arranged at a pre-assembly site in accordance with another embodiment of the invention.

[0039] Fig. 8 is a view similar to Fig. 7, illustrating a service lift operational within the upper tower portion. Fig. 9 is a view similar to Figs. 7 and 8, illustrating the service lift moved to a stowed position within the upper tower portion and disconnected for transportation of the upper tower portion.

[0040] Fig 10 is a side view of the upper tower portion and the lower tower portion connected together at a tower assembly site to form an intermediate assembled tower.

[0041] Fig. 11 is a view similar to Fig. 10, illustrating the upper tower portion and the lower tower portion connected together at the tower assembly site, with the service lift installed and operational within the tower.

[0042] Fig. 12 is a side view of the tower attached to an offshore foundation at a wind turbine site with the service lift assembled and operational.

[0043] Detailed Description

[0044] With reference to Figs. 1 through 12, embodiments of a wind turbine tower having a service lift are shown. In particular, the tower is a multi-part tower and a method for installing and operating the service lift in the multi-part wind turbine tower is shown in detail. In that regard, the wind turbine tower may be pre-assembled in two separate tower portions at one location, such as a pre-assembly site, and then assembled together at another location, such as a tower assembly site. The service lift is used to transport personnel and parts within the tower during installation, maintenance and service of the wind turbine. In that regard, when the tower is fully assembled, the service lift is configured to traverse a height of the tower that includes both tower portions. In order to simplify the installation of the service lift at the tower assembly site or the wind turbine site, the tower portions are assembled or staged beforehand at the pre-assembly site with all the necessary components required to operate the service lift at both the pre-assembly site and at the assembly site or the wind turbine site. That way, the service lift can be load tested at the pre-assembly site, for example. Further, this reduces the need for extensive assembly of the service lift at the assembly site or the wind turbine site. According to aspects of the invention, the service lift is installed in one tower portion at the pre-assembly site. In particular, the service lift is operational within the one of the tower portions such that one or more operational tests may be conducted at the pre-assembly site to verify proper operation of the service lift, for example. These and other benefits of the present invention will be described more fully below.

[0045] Turning with reference to Fig. 1 , a wind turbine 10 is shown which includes a multipart tower 12 assembled with a service lift 22 (e.g., Fig. 6) that is operational inside the tower 12 in accordance with embodiments of the invention. The wind turbine 10 further includes a nacelle 14 disposed at the apex of the tower 12, a rotor 16 operatively coupled to a generator (not shown) housed inside the nacelle 14, and a gearbox (not shown) also housed inside the nacelle 14. In addition to the generator and gearbox, 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, or external to the nacelle 14, and operates to elevate the nacelle 14 and the 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.

[0046] The rotor 16 may include a central 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 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.

[0047] The rotor 16 may be coupled to the gearbox directly or indirectly by a drive shaft (not shown) to form a rotor assembly. Either way, the gearbox transfers the rotation of the rotor 16 through a coupling (not shown) to the generator. Wind exceeding a minimum speed may activate the rotor 16, causing the rotor 16 to rotate in a direction substantially perpendicular to the wind, and applying torque to the input shaft of the generator. 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. In this way, the kinetic energy of the wind may be harnessed by the wind turbine 10 for power generation.

[0048] As briefly described above, aspects of the present invention are directed to the assembly and installation of the wind turbine service lift 22 within the wind turbine tower 12. The service lift 22 may be a temporary or permanent installation within the wind turbine tower 12. As will be described in further detail below, this involves assembling the service lift 22 within portions or sections of the wind turbine tower 12 at a pre-assembly site. The portions of the tower 12 can then be further assembled at another location, such as a tower assembly site or an installation site for the wind turbine 10, for example. In that regard, the tower 12 may be for an offshore wind turbine (left side of the wind turbine 10 of Fig. 1 ) or an onshore wind turbine (right side of the wind turbine 10 of Fig. 1 ). Specifically, the tower 12 may be attachable to an offshore foundation 24 or an onshore foundation 26, as shown. To install the tower 12 at an offshore foundation 24 of an offshore wind turbine site, an offshore installation vessel 28 or other type of watercraft may be used to transport the tower 12 to the offshore foundation 24 for installation. Although not shown, the offshore installation vessel 28 may feature a crane onboard. The crane may serve a dual purpose, allowing for the assembly of the tower 12 on the offshore installation vessel 28 and the unloading of the assembled tower 12 from the offshore installation vessel 28 onto the offshore foundation 24 where it can be properly attached. To install the tower 12 at the onshore foundation 26 of an onshore wind turbine site, a land vehicle may be employed to transport the tower 12 to the onshore foundation 26 for installation. A crane may be used to lift the tower 12 onto the foundation 26, for example. Although embodiments of the tower 12 and assembly of the service lift 22 within the tower 12 are shown and described in conjunction with a tower for use with an offshore wind turbine site, the tower 12 and methods for installing the service lift 22 within the tower 12 are not limited to this specific application. To this end, the drawings are not intended to be limiting.

[0049] Referring now to Figs. 2-6, a method of assembling the service lift 22 and the wind turbine tower 12 will be described according to a first embodiment of the invention. As shown in Fig. 2, the wind turbine tower 12 includes an upper tower portion 30 and a lower tower portion 32 arranged at a pre-assembly site 34. Thus, the tower 12 may be considered a two-part tower. The pre-assembly site 34 includes an upper tower stand 36 configured to receive and support the upper tower portion 30 and a lower tower stand 38 that is configured to receive and support the lower tower portion 32, particularly for certain pre-assembly or pre-installation activities, as will be described in further detail below. The pre-assembly site 34 defines a storage system 40 for portions of the wind turbine tower 12. Specifically, the pre-assembly site 34 may serve as a storage site where multiple tower portions 30, 32 and other tower components may be staged until they are ready to be assembled elsewhere. The pre-assembly site 34 may be located quayside to minimize transportation requirements and facilitate loading of the tower portions 30, 32 onto the service offshore installation vessel 28, for example. Therefore, the tower sections 30, 32 need only be transported a short distance and can be quickly loaded onto the offshore installation vessel 28 for shipment to the offshore wind turbine site, for example.

[0050] With continued reference to Fig. 2, the upper tower stand 36 is configured to support the upper tower portion 30 which includes a first upper tower section 42 and a second upper tower section 44 coupled together at an interface 46. The first and second upper tower sections 42, 44 are elongate, tubular structures that extend longitudinally between opposite open ends where a flange 48 is located. The flanges 48 may be used to couple the tower sections 42, 44 together at the interface 46 or to the tower stand 36, for example. As shown, the upper tower portion 30 includes two tower sections 42, 44 which may be similarly sized or different in size. However, in an alternative embodiment, the upper tower portion 30 may include fewer or more tower sections 42, 44, such as three, for example. The upper tower portion 30 may arrive at the pre-assembly site 34 as an assembled unit that is attachable or connectable to the upper tower stand 36. Alternatively, the upper tower portion 30 may be assembled at the pre-assembly site 34, such as by stacking the tower sections 42, 44 one on top of the other on the upper tower stand 36. As shown, each tower section 42, 44 may have one or more intermediate service platforms 50 arranged at different points along its length. The service platforms 50 serve as safe working areas for maintenance personnel and can be accessed via the service lift 22 or a ladder (not shown) within the upper tower portion 30, for example. With continued reference to Fig. 2, the upper tower portion 30 extends between an upper end 52 and a lower end 54 to define an interior 56 within which components of the service lift 22 are housed, for example. As shown, the first upper tower section 42 may define the upper end 52 of the upper tower portion 30 and the second upper tower section 44 may define the lower end 54 of the upper tower portion 30. As shown, the lower end 54 is configured to be positioned on the upper tower stand 36 such that the upper tower portion 30 is supported by the upper tower stand 36. The lower end 54 of the upper tower portion 30 may then be attached to the upper tower stand 36. The upper tower stand 36 may be affixed to the ground or other surface at the preassembly site 34 to support the upper tower portion 30 thereon. The upper tower stand 36 extends from a base 58 to an open end 60 that is open to an interior 62 of the upper tower stand 36. As shown, the open end 60 of the upper tower stand 36 is correspondingly sized to receive the lower end 54 of the upper tower portion 30. For example, the open end 60 of the upper tower stand 36 may include a flange configured to receive the flange 48 at the lower end 54 of the upper tower portion 30 for attachment. When the upper tower portion 30 is positioned on and secured to the open end 60 of the upper tower stand 36, the interior 56 of the upper tower portion 30 is placed in communication with the interior 62 of the upper tower stand 36.

[0051] As shown in Fig. 2, the upper tower stand 36 includes within its interior 62 a pedestal 64 configured to receive the service lift 22, particularly when the service lift 22 is not connected to the upper tower portion 30 and requires support. In that regard, the pedestal 64 is configured to support the service lift 22 and may further provide a working area for maintenance personnel to access the service lift 22 for installation and maintenance activities, as well as to perform operational tests on the service lift 22, for example. The upper tower stand 36 also includes a temporary power supply 66 configured to power at least the service lift 22, as will be described in further detail below. The temporary power supply 66 may be located on the pedestal 64, as shown, or located elsewhere within the upper tower stand 36.

[0052] Before the upper tower portion 30 is attached to the upper tower stand 36 at the preassembly site 34, the service lift 22 may first be arranged on the pedestal 64. When the service lift 22 is in position on the pedestal 64 within the upper tower stand 36, the upper tower portion 30 may then be attached to the upper tower stand 36, as illustrated in Fig. 2. This avoids the need for a large crane to lower the service lift 22 down through the upper tower portion 30 to the pedestal 64, for example. To this end, the service lift 22 is accessible from the interior 56 of the upper tower portion 30 once the upper tower portion 30 has been attached to the upper tower stand 36. It is noted that the size of the service lift 22 is exaggerated to better illustrate aspects of the invention. Thus, when arranged on the pedestal 64, the service lift 22 may be positioned either entirely within the interior 62 of the upper tower stand 36 or partially within the interior 56, 62 of both the upper tower portion 30 and the upper tower stand 36.

[0053] As briefly described above, the service lift 22 is configured to be installed in the upper tower portion 30 at the pre-assembly site 34 so as to be operational. That is, the service lift 22 is operational within the upper tower portion 30 such that one or more operational tests may be conducted at the pre-assembly site 34 to verify proper operation of the service lift 22, for example. After one or more operational tests are conducted, the service lift 22 may be disconnected and secured in place so that the upper tower portion 30 may be transported to a tower assembly site, for example. In that regard, the first upper tower section 42 and the second upper tower section 44 of the upper tower portion 30 each include components required to operate the service lift 12 within the upper tower portion 30 as well as in the tower 12 once fully assembled elsewhere. Specifically, the upper tower portion 30 includes a lift wire assembly 68, an upper power cable 70, and a pulley guide wire 72, as shown in Fig. 2. These components form part of a service lift system 74 (e.g., Fig. 6) that provides for vertical movement (i.e. , up and down) of the service lift 22 within the upper tower portion 30 at the pre-assembly site 34 as well as vertically within the assembled tower 12.

[0054] As will be understood by a person skilled in the art, the service lift system 74 includes the service lift 22 which is moved vertically (e.g., up and down) along a service lift 22 path that may extend for an entire length of the tower 12. In particular, the service lift 22 is movable along at least one traction wire of the lift wire assembly 68. The lift wire assembly 68 may further include one or more safety wires, for example. The upper power cable 70, otherwise referred to as a traveling power cable, supplies energy to the service lift 22. The upper power cable 70 may be guided by a pulley as the service lift 22 travels along the service lift 22 path. These and other components of the lift system 74 will be described in further detail below, when appropriate. In another embodiment, rather than being guided by the lift wire assembly 68 (e.g. taut lines or cables), the service lift 22 may be guided by a rail, a ladder or any other rigid guiding element. The rail or ladder may extend from the top to the bottom of the wind turbine tower 12, for example.

[0055] With continued reference to Fig. 2, the first upper tower section 42 includes the lift wire assembly 68 which may be suspended from a support member 76 located adjacent to the upper end 52 of the upper tower portion 30. The support member 76 may be a crossbeam configured to support the lift wire assembly 68 of the service lift 22, especially when tensioned, as well as withstand forces associated with movement of the service lift 22 within the tower 12. As shown, the lift wire assembly 68 includes a first, fixed end 78 attached or anchored to the support member 76 and a second, free end 80 suspended within the first upper tower section 42. As will be described in further detail below, the service lift 22 is configured to move vertically along the lift wire assembly 68 which keeps the service lift 22 stable and properly aligned during its movement within the assembled tower 12. To accommodate movement of the service lift 22 within the assembled tower 12, a length of the lift wire assembly 68 may be greater than a length of the first upper tower section 42. The extra length of the lift wire assembly 68 is managed by arranging the free end 80 of the lift wire assembly 68 into a coil, as shown. The coiled free end 80 of the lift wire assembly 68 may either be suspended within the first upper tower section 42 or secured to it, for example. In either case, the first upper tower section 42 may be transported to the pre-assembly site with the lift wire assembly 68 already installed and the free end 80 coiled, as shown. As will be understood by a person skilled in the art, the lift wire assembly 68 may comprise several wires and cables such as a traction wire or cable, a safety wire or cable, and one or more guide wires, for example.

[0056] With continued reference to Fig. 2, the second upper tower section 44 includes the upper power cable 70 which is connected to and supported from the flange 48 at the interface 46 between the first and second tower sections 42, 44. The upper power cable 70 is configured to power movement of the service lift 22 and includes a fixed cable portion 82 and a traveling cable portion 84 that are electrically connected at a cable interface 86 to form the upper power cable 70. The cable interface 86 may be located adjacent to the interface 46 between the tower sections 42, 44. As shown, a section of the power cable 70 where the cable interface 86 is located extends a length along the flange 48 to space the fixed cable portion 82 a distance from the traveling cable portion 84 about a circumference of the flange 48. The fixed cable portion 82 is attached to the flange 48 and extends to a free end 88 adjacent the lower end 54 of the upper tower portion 30 and the upper tower stand 36. For example, the fixed cable portion 82 may be routed in cable trays along a main access ladder within the tower 12. The traveling cable portion 84 is suspended from the flange 48 and extends to a free end 90 adjacent the lower end 54 of the upper tower portion 30 and the upper tower stand 36. To accommodate movement of the service lift 22 within the assembled tower 12, the length of the fixed cable portion 82 and the traveling cable portion 84 are greater than the length of at least the second upper tower section 44. The extra length of cable is managed by arranging the free end 88, 90 of the fixed cable portion 82 and the traveling cable portion 84, respectively, into a coil. The coiled free ends 88, 90 of the fixed cable portion 82 and the traveling cable portion 90 may either be suspended within the second upper tower section 44 or secured to it, for example. In either case, the second upper tower section 44 may be transported to the pre-assembly site 34 with the upper power cable 70 already installed and the respective free ends 88, 90 of the fixed cable portion 82 and the traveling cable portion 84, coiled, as shown.

[0057] As briefly described above, the second upper tower section 44 includes the pulley guide wire 72 which is connected to and supported from the flange 48 adjacent the interface 46. The pulley guide wire 72 is configured to receive a pulley 92 (e.g., Fig. 6) that is used to manage movement of the traveling power cable portion 84. Specifically, the pulley 92 is movably attached to the pulley guide wire 72 to receive the traveling power cable portion 84 to guide movement of the traveling power cable 84 as the service lift 22 traverses the lift wire assembly 68. The pulley guide wire 72 includes a fixed end 94 that is attached to and suspended from either or both of the flanges 48 at the interface 46 between the first and second upper tower sections 42, 44. For example, the fixed end 94 may be connected to the upper flange 48 of the second upper tower section 44. The pulley guide wire 72 extends from the fixed end 94 to a free end 96 adjacent the lower end 54 of the upper tower portion 30 and the upper tower stand 36. To accommodate movement of the service lift 22 within the assembled tower 12, the length of the pulley guide wire 72 is greater than the length of at least the second upper tower section 44. The extra length of cable is managed by arranging the free end 96 of the pulley guide wire 72 into a coil, as shown. The coiled free end 96 of the pulley guide wire 72 may either be suspended within the second upper tower section 44 or secured to it, for example. In either case, the second upper tower section 44 may be transported to the pre-assembly site with the pulley guide wire 72 already installed and the free end 96 coiled, as shown.

[0058] With continued reference to Fig. 2, details of the lower tower portion 32 will now be described. As shown, the lower tower portion 32 extends between an upper end 100 and a lower end 102 to define an interior 104 within which components of the service lift 22 are housed, for example. As shown, the lower end 104 is configured to be positioned on the lower tower stand 38 such that the lower tower portion 32 is supported by the lower tower stand 38. The lower end 104 of the lower tower portion 32 may then be attached to the lower tower stand 38. The lower tower portion 32 further includes a first lower tower section 106 and a second lower tower section 108 attached together at an interface 110. The first and second lower tower sections 106, 108 are elongate, tubular structures that extend longitudinally between open ends where a flange 112 is located. The flanges 112 may be used to couple the tower sections 106, 108 together at the interface 110 or to the lower tower stand 38, for example. As shown, the lower tower portion 32 includes two tower sections 106, 108 which may be similarly sized or different in size. In an alternative embodiment, the lower tower portion 32 may include fewer or more tower sections 106, 108, such as three, for example. The lower tower portion 32 may arrive at the pre-assembly site 34 as an assembled unit that is attached to the lower tower stand 38. Alternatively, the lower tower portion 32 may be assembled at the pre-assembly site 34, such as by stacking the tower sections 106, 108 one on top of the other on the lower tower stand 38. Each tower section 106, 108 may have one or more intermediate service platforms 50 installed at different points along its length, as necessitated by the tower design.

[0059] As shown, the first lower tower section 106 may define the upper end 100 of the lower tower portion 32 and the second lower tower section 108 may define the lower end 102 of the upper tower portion 32. The lower end 102 of the lower tower portion 32 is configured to be attached to the lower tower stand 38 via the flange 112, for example. In that regard, the lower tower stand 38 may be affixed to the ground or other surface at the pre-assembly site 34 to support the lower tower portion 32 thereon. In particular, the lower tower stand 38 extends from a base 114 to an open end 116 that is open to an interior 118 of the lower tower stand 38. As shown, the open end 116 of the lower tower stand 38 is correspondingly sized to receive the lower end 102 of the lower tower portion 32. For example, the open end 116 of the lower tower stand 38 may include a flange configured to receive the flange 112 at the lower end 102 of the lower tower portion 32 for attachment. When the lower tower portion 32 is secured to the open end 116 of the lower tower stand 38, the interior 104 of the lower tower portion 32 is placed in communication with the interior 118 of the lower tower stand 38. To this end, the interior 104 of the lower tower portion 32 may be accessed from the interior 118 of the lower tower stand 38 to access certain components of the service lift 22, as will be described in further detail below.

[0060] With continued reference to Fig. 2, the lower tower portion 32 includes certain other components of the service lift 22 required to operate the service lift 22 within the tower 12 once it has been assembled. In that regard, the lower tower portion 32 includes a lower power cable 120 connected to a power supply box 122. When the tower 12 is fully assembled, the lower power cable 120 is configured to be attached to the upper power cable 70 of the upper tower portion 30 to provide power to the service lift 22. The power supply box 122 is mounted to the second lower tower section 108 adjacent to the lower end 102 of the lower tower portion 32. The lower power cable 120 includes a fixed end 124 configured to be electrically connected to the power supply box 122. The lower power cable 120 extends from the fixed end 124 to a free end 126 that is located adjacent to the upper end 100 of the lower tower portion 32. For instance, the lower power cable 120 may be arranged in a cable tray that extends along a tower wall of the lower tower portion 32. The length of the lower power cable 120 may need to be greater than the length of the lower tower portion 32, for example, to reach the upper tower portion 30 for connection to the upper power cable 70. The extra length of the lower power cable 120 is managed by arranging the free end 126 of the lower power cable 120 into a coil. The coiled free end 126 of the lower power cable 120 may be secured to the lower tower portion 32, such as to the flange 112 at the upper end 100 of the lower tower portion 32, for example. The lower tower portion 32 may be transported to the pre-assembly site 34 with the lower power cable 120 already installed and the free end 126 coiled, as shown. The fixed end 124 of the lower power cable 120 may be connected to the power supply box 122 at the pre-assembly site 34, for example.

[0061] Having now described certain details of the upper and lower tower portions 30, 32, a method of assembling the tower 12, including installing and testing of the service lift 22, will now be described with reference to Figs. 1-6 in accordance with one embodiment of the invention. In that regard, the upper and lower tower portions 30, 32 are received at the pre-assembly site 34 as described above. Specifically, the upper and lower tower portions 30, 32 are arranged on respective upper and lower tower stands 36, 38, as shown in Fig. 2. With respect to the lower tower portion 32, the fixed end 124 of the lower power cable 120 may be connected to the power supply box 122 if not already connected. Similarly, the free end 126 of the lower power cable 120 may be arranged at the upper end 100 of the lower tower portion 32 where it may be coiled and secured. At this point, the lower tower portion 32 is pre-assembled and ready to be transported from the pre-assembly site 34 elsewhere.

[0062] With respect to the upper tower portion 30, and in particular the service lift 22, once the upper tower portion 30 has been secured to the upper tower stand 36 to be supported, as shown in Fig. 2, the service lift 22 may be temporarily assembled so as to be operational within the upper tower portion 30 to conduct one or more operational tests to verify proper operation of the service lift 22. In that regard, the free end 80 of the lift wire assembly 68 may be uncoiled and connected to the pedestal 64 of the upper tower stand 36, as shown in Fig. 3. Moreover, the service lift 22 is operatively connected to the lift wire assembly 68, which may include a traction wire or cable, a safety wire or cable, and one or more guide wires, for example, so as to be movable along the lift wire assembly 68. In that regard, the service lift 22 may include a motor configured to drive movement of the service lift 22 along the lift wire assembly 68. To this end, once the lift wire assembly 68 has been connected to the service lift 22 and the pedestal 64, the lift wire assembly 68, and in particular the traction wire(s), guide wire(s), and safety wire(s) may be tensioned appropriately so that the service lift 22 may be commissioned and load tested within the upper tower portion 30, for example.

[0063] With continued reference to Fig. 3, a temporary power cable 128 is connected between the temporary power supply 66 and the service lift 22 to power movement of the service lift 22 vertically along the lift wire assembly 68. Once the lift wire assembly 68 and the temporary power cable 128 have been installed, the service lift 22 may be considered operational for purposes of conducting one or more operational tests, for example. Once testing and commissioning operations are complete, the service lift 22 is further operated to move the service lift 22 upwardly from the pedestal 64 and the upper tower stand 36 to the interface 46 between the first and second upper tower sections 42, 44 where the service lift 22 may be secured in place to the upper tower portion 30. In that regard, Fig. 4 illustrates the service lift 22 moved to a stowed position where the service lift 22 is secured to the upper tower portion 30 approximate the interface 46. When in the stowed position, the service lift 22 is at a location that is vertically spaced from the upper tower stand 36. In the embodiment shown, the service lift 22 is secured to the upper tower portion 30 with one or more connectors 130.

[0064] In one embodiment, the service lift 22 is secured to one of the tower flanges 48 at the interface 46 with one or more connectors 130 in the form of magnetic brackets which may be attached to one or more of the tower flanges 48. In another embodiment, the service lift 22 is secured to one of the tower flanges 48 at the interface 46 with one or more connectors 130 in the form of bolts. However, other securing means for securing the service lift 22 to the upper tower portion 30 in the stowed position are possible, such as clips, screw clamps, clamp brackets, screw-in brackets, tension brackets, or other suitable fastening hardware.

[0065] With continued reference to Fig. 4, once the service lift 22 has been moved to the stowed position and secured to the upper tower portion 30 at the interface 46, components of the service lift 22 may be disconnected so that the upper tower portion 30 may be transported to the tower assembly site, for example. In that regard, the tension on the lift wire assembly 68 is released and the free end 80 of the lift wire assembly 68 is disconnected from the pedestal 64 of the upper tower stand 36. The lift wire assembly 68 may remain connected to the service lift 22 and the free end 80 of the lift wire assembly 68 may be arranged back into a coil for storage. To this end, the coiled free end 80 of the lift wire assembly 68 may be located or stored adjacent to the lower end 54 of the upper tower portion 30. In addition, the temporary power cable 128 is disconnected from the service lift 22 and stored so as not to interfere with removal of the upper tower portion 30 from the upper tower stand 36. Fig. 4 illustrates the upper tower portion 30 and the lower tower portion 32 preassembled and ready to be moved to a tower assembly site where the tower portions 30, 32 may be further assembled. In that regard, the upper tower portion 30 and the lower tower portion 32 may disconnected and removed from the upper tower stand 36 and the lower tower stand 38, respectively, with a crane for example. The upper and lower tower portions 30, 32 may be transported to a tower assembly site 132 with an appropriate transport vehicle such as a crane, a large truck, a train, or a vessel, for example. As shown in Fig. 5, once at the tower assembly site 132, the upper tower portion 30 is arranged vertically on top of the lower tower portion 32 to form an intermediate assembled wind turbine tower 12a. The tower assembly site 132 may be onshore, such as quayside, on the offshore installation vessel 28 that carries the tower 12a to the offshore foundation 24, or offshore, such as at the offshore foundation 24, for example. In either case, the lower end 54 of the upper tower portion 30 is attached to the upper end 100 of the lower tower portion 32 at a tower portion interface 134 at the tower assembly site 132 to form the intermediate assembled tower 12a, as shown in Fig. 5. The upper end 52 of the upper tower portion 30 may form the apex of the tower 12, 12a. The lower end 54 of the lower tower portion 32 may form the base of the tower 12, 12a which includes an entrance platform 136. The lower end 54 of the lower tower portion 32 may also include an access door 137, as shown. The tower 12a is considered to be intermediate assembled because the components of the service lift 22, such as the lift wire assembly 68, power cables 70, 120, and the pulley guide wire 72, for example, remain disconnected while the intermediate assembled tower 12a is at the tower assembly site 132. In another embodiment, some or all of the components of the service lift 22 may be assembled at the tower assembly site 132. For example, the free end 126 of the lower power cable 120 may be connected to the free end 88 of the fixed cable portion 82 of the upper power cable 70.

[0066] In a non-illustrated embodiment, the foundation 24 includes what is known to the skilled person as an extended transition piece. An extended transition piece is a tubular structure similar to a smaller tower section that is attached to the foundation 24 and extends above said foundation 24. The extended transition piece at its upper end interfaces to the lower end 54 of the lower tower portion 32. The access door 137 in this embodiment is in the extended transition piece. The lower end 54 of the lower tower portion 32 is free of an access door 137.

[0067] Referring now to Figs. 5 and 6, the intermediate assembled tower 12a is next transported from the tower assembly site 132 to a wind turbine site 138. In the embodiment shown, the tower assembly site 132 is on the offshore installation vessel 28. In that regard, the offshore installation vessel 28 moves the intermediate assembled tower 12a to the wind turbine site 138 where the offshore foundation 24 is located. As described above, the offshore installation vessel 28 may feature a crane onboard that is used to unload the intermediate assembled tower 12a from the offshore installation vessel 28 onto the offshore foundation 24 where it can be properly attached. In particular, the base of the tower 12a is attached to the offshore foundation 24 to secure the tower 12a thereto such that the tower 12a is supported on the offshore foundation 24, as shown in Fig. 6. When so positioned, the service lift 22 may be assembled within the tower 12a as described in further detail below.

[0068] With continued reference to Figs. 5, the service lift 22 is assembled within the tower 12a by connecting the free end 80 of the lift wire assembly 68 and the free end 96 of the pulley guide wire 72 to the offshore foundation 24 or the entrance platform 136 at the base of the tower 12a. The lift wire assembly 68 and the pulley guide wire 72 may then be tensioned appropriately. If not already connected, the fixed end 124 of the lower power cable 120 may be connected to the power supply box 122 in the lower tower portion 32 of the wind turbine tower 12a. The free end 126 of the lower power cable 120 may be connected to the free end 88 of the fixed cable portion 82 of the upper power cable 70 at a cable interface 140. When connected, the upper power cable 82 and the lower power cable 120 are configured to supply electricity to power the service lift 22. In that regard, the free end 90 of the traveling cable portion 84 of the upper power cable 70 may be routed through the pulley 92 of the pulley guide wire 72 and connected to the service lift 22, as shown. Once the service lift 22 is electrically connected to the power supply box 122 via the upper and lower power cables 70, 120, the service lift 22 may be operational.

[0069] Before the service lift 22 can be operated, it first needs to be released from the upper tower portion 30. This is done by disconnecting or deactivating the one or more connectors 130, which allows the service lift 22 to be moved from its stowed position. Once released, the service lift 22 may be operated to traverse the lift wire assembly 68 and thus a height of the tower 12. The height of the tower 12 may be defined by a distance between the upper end 52 of the upper tower portion 30 (i.e. , the apex of the tower 12) and the lower end 54 of the lower tower portion 32 (i.e., the base of the tower 12). As shown, the lift wire assembly 68 extends for substantially the full height of the tower 12. That way, the service lift 22 is moveable along the lift wire assembly 68 for substantially the full height of the tower 12. To this end, the tower 12 shown in Fig. 6 may be considered fully assembled to receive other parts of the wind turbine 10, such as the nacelle 14, for example.

[0070] To ensure smooth, organized movement of the traveling cable portion 84 of the upper power cable 70 when the service lift 22 travels along the lift wire assembly 68, the pulley 92 is used. In that regard, the pulley 92 is configured to receive the traveling cable portion 84 and move along the pulley guide wire 72 with movement of the service lift 22. In particular, as the service lift 22 moves up or down along the lift wire assembly 68, the pulley 92 moves along the pulley guide wire 72 accordingly. To this end, the slack in the traveling cable portion 84 of the power cable 70 may increase when the service lift 22 is closer to the apex 52 of the tower 12, as compared to when it is nearer to the base 136 of the tower 12. As shown in Fig. 6, the pulley guide wire 72 is positioned in close proximity to the sidewalls of the upper and lower tower portions 30, 32 rather than at the axial center of the tower 12. By routing the traveling cable portion 84 through the movable pulley 92 that is attached to the pulley guide wire 72, the traveling cable portion 84 of the upper power cable 70 is also kept away from the axial center of the tower 12. This prevents the traveling cable portion 84 from colliding with other wind turbine components that may be positioned or moved through the axial center of the tower 12.

[0071] Referring now to Figs. 7-12, a method of assembling the tower 12, including installing and testing of the service lift 22, will now be described in accordance with another embodiment of the invention. In that regard, like reference numerals represent like features compared to the embodiment described above with respect to Figs. 1-6. The primary difference between the method of this embodiment and the method of the previously described embodiment is that the upper power cable 70, and in particular the traveling cable portion 84 of the upper power cable 70, is connected to the service lift 22 to power the service lift 22 at the pre-assembly site 34. Thus, the upper power cable 70 is used to supply power to the service lift 22 at the pre-assembly site 34 instead of using the previously described temporary power cable 128, for example.

[0072] With reference to Fig. 7, the upper and lower tower portions 30, 32 are received at the pre-assembly site 34 as described above. Specifically, the upper and lower tower portions 30, 32 are arranged on respective upper and lower tower stands 36, 38, as shown. With respect to the lower tower portion 32, the fixed end 124 of the lower power cable 120 may be connected to the power supply box 122, if not already connected. Similarly, the free end 126 of the lower power cable 120 may be arranged at the upper end 100 of the lower tower section 32 where it may be coiled and secured. At this point, the lower tower section 32 is pre-assembled and is ready to be transported from the pre-assembly site 34 to the tower assembly site 132.

[0073] Once the upper tower portion 30 has been secured to the upper tower stand 36, the service lift 22 may be temporarily assembled so as to be operational within the upper tower portion 30 to conduct one or more operational tests to verify proper operation of the service lift 22. In that regard, the free end 80 of the lift wire assembly 68, which may include at least a traction wire or cable, a safety wire or cable, and one or more guide wires, for example, may be uncoiled and connected to the pedestal 64 of the upper tower stand 36, as shown in Fig. 8. Furthermore, the service lift 22 is operatively connected to the lift wire assembly 68, such as to the traction wire, so as to be movable along the lift wire assembly 68, as described above. The free end 96 of the pulley guide wire 72 is also uncoiled and connected to the pedestal 64 of the upper tower stand 36. The lift wire assembly 68 and the pulley guide wire 72 may be appropriately tensioned so that one or more operational tests may be performed to commission the service lift 22, for example.

[0074] With continued reference to Fig. 8, the upper power cable 70 is connected to the temporary power supply 66 and the service lift 22 to power movement of the service lift 22 vertically along the lift wire assembly 68 within the upper tower portion 30. In that regard, the free end 90 of the traveling cable portion 84 is uncoiled and routed through the pulley 92 of the pulley guide wire 72 and connected to the service lift 22. To accommodate movement of the service lift 22 within the assembled tower 12, the length of the traveling cable portion 84 may be greater than that required to move the service lift 22 within the upper tower portion 30. The extra length of the traveling cable portion 84 may be managed by arranging a section or length of the traveling cable portion 84 into a coil 142, as shown. Once the lift wire assembly 68, upper power cable 70, and pulley guide wire 72 have been installed, the service lift 22 may be considered operational for purposes of conducting one or more operational tests at the preassembly site 34, for example.

[0075] With reference to Figs. 8 and 9, once testing and commissioning operations are complete, the service lift 22 is further operated to move the service lift 22 upwardly from the pedestal 64 and the upper tower stand 36 to the interface 46 between the first and second upper tower sections 42, 44 where the service lift 22 may be secured to the upper tower portion 30. In particular, the service lift 22 is secured to the upper tower portion 30 at a location that is vertically spaced from the upper tower stand 36. In that regard, Fig. 9 illustrates the service lift 22 moved to a stowed position where the service lift 22 is secured to the upper tower portion 30 at the interface 46. Like the embodiment described above, the service lift 22 is secured to the upper tower portion 30 with one or more connectors 130. Once the service lift 22 has been moved to the stowed position where the service lift 22 is secured to the upper tower portion 30, components of the service lift 22 may be disconnected so that the upper tower portion 30 may be transported to the tower assembly site 132, for example, as described in further detail below.

[0076] Fig. 9 illustrates the service lift 22 disconnected and so that the upper tower portion 30 may be moved to the tower assembly site 132. Specifically, the tension on the lift wire assembly 68 is released and the free end 80 of the lift wire assembly 68 is disconnected from the pedestal 64 of the upper tower stand 36 and arranged into a coil. Similarly, the tension on the pulley guide wire 72 is released and the free end 96 of the pulley guide wire 72 is disconnected from the pedestal 64 of the upper tower stand 36 and arranged into a coil. The free end 88 of the fixed cable portion 72 of the upper power cable 70 is disconnected from the temporary power source 66 and arranged into a coil. It is important to note that the free end 90 of the traveling cable portion 84 of the upper power cable 70 remains connected to the service lift 22, and the traveling cable portion 84 remains connected to the pulley 92 of the pulley guide wire 72. This eliminates the need to establish these connections at the tower assembly site 132, for example, resulting in time and cost savings during installation.

[0077] Fig. 9 illustrates the upper tower portion 30 and the lower tower portion 32 preassembled and ready to be moved to the tower assembly site 132 where the tower portions 30, 32 may be assembled to form the wind turbine tower 12. In that regard, Fig. 10 shows the upper tower portion 30 arranged vertically on top of the lower tower portion 32 at the tower assembly site 132 to form an intermediate assembled wind turbine tower 12b. Like the previously described embodiment, the tower 12b is considered to be intermediate assembled because the components of the service lift 22, such as the lift wire assembly 68, power cables 70, 120, and the pulley guide wire 72, for example, remain disconnected, or are only partially connected, for a period of time while the intermediate assembled tower 12b is at the tower assembly site 132. In the embodiment shown, the tower assembly site 132 is on the offshore installation vessel 28, however, the tower assembly site 132 may be quayside, for example.

[0078] With reference to Figs. 10 and 11 , the service lift 22 may be assembled within the tower 12b at the tower assembly site 132. In that regard, the free end 80 of the lift wire assembly 68 and the free end 96 of the pulley guide wire 72 are connected to the entrance platform 136 at the base of the tower 12b. The lift wire assembly 68 and the pulley guide wire 72 may then be tensioned appropriately. If not already connected, the fixed end 124 of the lower power cable 120 may be connected to the power supply box 122 in the lower tower portion 32 of the wind turbine tower 12b. The free end 126 of the lower power cable 120 may be connected to the free end 88 of the fixed cable portion 82 of the upper power cable 70 at the cable interface 140. When connected, the upper power cable 70 and the lower power cable 120 are configured to supply electricity to power the service lift 22. At this point, the service lift 22 may be released from the upper tower portion 30 and moved to a rest position near the base 136 of the tower, as shown in Fig. 11 . This is performed by disconnecting or deactivating the one or more connectors 130, allowing the service lift 22 to be moved from its stowed position. Once released, the service lift 22 will be fully operational and may be operated to travel downwardly along the lift wire assembly 68 toward the base 136 of the assembled tower 12. In another embodiment, the service lift 22 may remain in the stowed position, secured to the upper tower portion 30, until the tower 12 is installed to the offshore foundation 24 at the wind turbine site 138.

[0079] Referring now to Fig 12, the assembled tower 12 is next transported to the wind turbine site 138 for installation. In that regard, the offshore installation vessel 28 transports the tower 12 to the wind turbine site 138 where the offshore foundation 24 is located. As described above, the offshore installation vessel 28 may feature a crane onboard that is used to unload the tower 12 from the offshore installation vessel 28 onto the offshore foundation 24 where it can be properly attached. In particular, the base of the tower 12 is connected or attached to the offshore foundation 24 to secure the tower 12 thereto such that the tower 12 is supported on the offshore foundation 24, as shown, with the service lift 22 being operational within the tower 12.

[0080] 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

Claims1 . A method of installing a service lift (22) in a wind turbine tower (12), the wind turbine tower (12) including an upper tower portion (30) and a lower tower portion (32), wherein the upper tower portion (30) is configured to be connected to the lower tower portion (32) to form the wind turbine tower (12), the method comprising: providing an upper tower stand (36) at a tower pre-assembly site (34); providing the upper tower stand (36) with the service lift (22); positioning the upper tower portion (30) of the wind turbine tower (12) on the upper tower stand (36) so that the upper tower portion (30) is supported on the upper tower stand (36); connecting the service lift (22) in the upper tower stand (36) to the upper tower portion (30) of the wind turbine tower (12) so that the service lift (22) is operational within the upper tower portion (30); operating the service lift (22) within the upper tower portion (30) of the wind turbine tower (12); and securing the service lift (22) to the upper tower portion (30) at a location vertically spaced from the upper tower stand (36) for subsequent assembly of the wind turbine tower (12).

2. The method of claim 1 , wherein the upper tower portion (30) includes a lift wire assembly (68) having a first fixed end (78) attached to the upper tower portion (30) adjacent an upper end (52) thereof and a second free end (80), and wherein connecting the service lift (22) in the upper tower portion (30) so as to be operational comprises: connecting the free end (80) of the lift wire assembly (68) to the upper tower stand (36); and connecting the lift wire assembly (68) to the service lift (22) so that the service lift (22) is moveable along the lift wire assembly (68).

3. The method of claim 1 or 2, wherein the upper tower stand (36) further includes a temporary power supply (66), and wherein the method further comprises: connecting the service lift (22) to the temporary power supply (66) in the upper tower stand (36) so that the service lift (22) is operational within the upper tower portion (30).

4. The method of claim 3, wherein connecting the service lift (22) to the temporary power supply (66) further comprises: providing a temporary power cable (128); and connecting the temporary power cable (128) between the temporary power supply (66) and the service lift (22).

5. The method of claim 3, wherein the upper tower portion (30) of the wind turbine tower (12) comprises: an upper power cable (70) connected to the upper tower portion (30), the upper power cable (70) including a fixed cable portion (82) and a traveling cable portion (84) connected at a cable interface (86) to form the upper power cable (70), wherein the fixed cable portion (82) includes a free end (88) adjacent a lower end (54) of the upper tower portion (30), wherein the traveling cable portion (84) includes a free end (90) adjacent the lower end (54) of the upper tower portion (54), and wherein the method further comprises: connecting the free end (88) of the fixed cable portion (82) to the temporary power supply (66); and connecting the free end (90) of the traveling cable portion (84) to the service lift (22).

6. The method of claim 5, wherein the upper tower portion (30) further comprises: a pulley guide wire (72) having a fixed end (94) connected to the upper tower portion (30) and a free end (96) connected to the upper tower stand (36); and a pulley (92) movably attached to the pulley guide wire (72), and wherein connecting the free end (90) of the traveling cable portion (84) to the service lift (22) further comprises:connecting the free end (90) of the traveling cable portion (84) to the service lift (22) so as to engage the moveable pulley (92) on the pulley guide wire (72).

7. The method of any of the preceding claims, wherein subsequent to securing the service lift (22) to the upper tower portion (30), the method further comprises disconnecting the service lift (22) in the upper tower portion (30) from the upper tower stand (36) so that the service lift (22) is non-operational within the upper tower portion (30).

8. The method of claim 7, when dependent from claim 2, wherein disconnecting the service lift (22) from the upper tower stand (36) includes disconnecting the free end (80) of the lift wire assembly (68) from the upper tower stand (68).

9. The method of any of claims 7 or 8, when dependent from claim 3, wherein disconnecting the service lift (22) from the upper tower stand (36) includes disconnecting the service lift (22) from the temporary power supply (66).

10. The method of claim 9, when dependent from claim 5, wherein disconnecting the service lift (22) from the upper tower stand (36) includes disconnecting the free end (88) of the fixed cable portion (82) of the upper power cable (70) from the temporary power supply (66).11 . The method of any of claims 7-10, when dependent from claim 6, wherein disconnecting the service lift (22) from the upper tower stand (36) includes disconnecting the free end (96) of the pulley guide wire (72) from the upper tower stand (36).

12. The method of any of the preceding claims, wherein operating the service lift (22) within the upper tower portion (30) of the wind turbine tower (12) includes conducting one or more operational tests to verify proper operation of the service lift13. The method of any of the preceding claims, wherein the upper tower portion (30) includes a plurality of tower sections, and wherein securing the service lift (22) to the upper tower portion (30) includes securing the service lift (22) to the upper tower portion (30) at an interface (46) between two adjacent tower sections (42, 44) of the plurality of tower sections.

14. The method of any of the preceding claims, further comprising: providing a lower tower stand (38) at the tower pre-assembly site (34); and positioning the lower tower portion (32) of the wind turbine tower (12) on the lower tower stand (38) so that the lower tower portion (32) is supported on the lower tower stand (38), wherein the lower tower portion (32) includes a lower power cable (120) connected to the lower tower portion (32) and having a fixed end (124) adjacent a lower end (102) of the lower tower portion (32) for connection to a power supply box (122) mounted to the lower tower portion (32) and a free end (126) adjacent an upper end (100) of the lower tower portion (32) for connection to the upper power cable (120).

15. The method of any of the preceding claims, wherein the tower pre-assembly site (34) is onshore, and preferably quayside.

16. A method of assembling a wind turbine tower (12), comprising: installing a service lift (22) in the wind turbine tower (12) according to claim 14 or 15 at the tower pre-assembly site (34); moving the lower tower portion (32) from the tower pre-assembly site (34) to a tower assembly site (132); moving the upper tower portion (30) from the tower pre-assembly site (34) to the tower assembly site (132); and connecting the upper tower portion (30) to the lower tower portion (32) to form the wind turbine tower (12).

17. The method of claim 16, wherein the tower assembly site (132) is aboard an offshore installation vessel (28).

18. A method of installing a wind turbine tower (12) at an offshore wind turbine installation site (138), comprising: assembling the wind turbine tower (12) according to claim 16 or 17; connecting the wind turbine tower (12) to an offshore foundation (24); connecting the first fixed end (124) of the lower power cable (120) to the power supply box (122) in the lower tower portion (32) of the wind turbine tower (12); connecting the second free end (126) of the lower power cable (120) to the free end (88) of the fixed cable portion (82) of the upper power cable (70); connecting the free end (80) of the lift wire assembly (68) to an entrance platform (136) of the wind turbine tower (12); connecting the free end (96) of the pulley guide wire (72) to the entrance platform (136) of the wind turbine tower (12); and optionally connecting the free end (90) of the traveling cable portion (84) to the service lift (22).

19. The method of claim 18, further comprising releasing the service lift (22) from the upper tower portion (30) of the wind turbine tower (12) so as to be operational within the wind turbine tower (12).

20. A storage system (40) for a wind turbine tower (12) having a service lift (22), the wind turbine tower (12) including an upper tower portion (30) and a lower tower portion (32), the storage system (40) comprising: an upper tower stand (36) supporting the upper tower portion (30) of the wind turbine tower (12); a lower tower stand (38) supporting the lower tower portion (32) of the wind turbine tower (12), wherein the upper tower portion (30) comprises: an upper power cable (70) connected to the upper tower portion (30), the upper power cable (70) including a fixed cable portion (82) and a traveling cable portion (84) connected at a cable interface (86) to form the upper power cable (86), and the fixed cable portion (82) having a free end (88) adjacent the upper tower stand (36),a lift wire assembly (68) having a fixed end (78) connected to the upper tower portion (30) adjacent an upper end (52) thereof and a free end (80) adjacent the upper tower stand (36); a pulley guide wire (72) having a first end (94) connected to the upper tower portion (30) and a free end (96) adjacent the upper tower stand (36), wherein the service lift (22) is connected to the upper tower portion (30) at a location vertically spaced from the upper tower stand (36).21 . The storage system (40) of claim 20, wherein the lower tower portion (32) comprises: a lower power cable (120) having a fixed end (124) adjacent the lower tower stand (38) and a free end (126) adjacent an upper end (100) of the lower tower portion (32), wherein the fixed end (124) of the lower power cable (120) is connected to or configured to be connected to a power supply box (122) mounted to the lower tower portion (32).

22. The storage system (40) of claim 20 or 21 , wherein the upper tower stand (36) includes a temporary power supply (66).

23. The storage system (40) of any of claims 20-22, wherein the traveling cable portion (84) of the upper power cable (70) includes a free end (90) connected to the service lift (22).

24. The storage system (40) of claim 23, wherein the pulley guide wire (72) includes a pulley (92) movably connected thereto, and wherein the traveling cable portion (84) is connected to the service lift (22) so as to engage the pulley (92).

25. The storage system (40) of any of claims 20-24, wherein the upper tower portion (30) includes a plurality of tower sections, and wherein the service lift (22) is secured to the upper tower portion (30) at an interface (46) between two adjacent tower sections (42, 44) of the plurality of tower sections.

Images