System and method for assembling tower sections of a wind turbine lattice tower structure

A system for assembling a tower section of a lattice tower structure for a wind turbine may generally include a tower assembly fixture having a plurality of radially extending fixture arms, wherein each fixture arm extends between a first end and a second end. In addition, the system may include a plurality of trolleys. Each trolley may include a base frame configured to be coupled to one of the fixture arms between its first and second ends and a leg mount pivotally coupled to the base frame. The leg mount may be configured to be coupled to a bottom end of a support leg of the tower section such that, when each of the support legs is coupled to its respective leg mount, the support legs are supported above the tower assembly fixture at a substantially vertical orientation.

FIELD OF THE INVENTION

The present subject matter relates generally to assembling wind turbine towers and, more particularly, to a system and method for assembling tower components to form a lattice or “space frame” tower structure for a wind turbine.

BACKGROUND OF THE INVENTION

Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, generator, gearbox, nacelle, and one or more rotor blades. The rotor blades capture kinetic energy of wind using known airfoil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy. A power converter typically regulates the flow of electrical power between the generator and a grid.

Wind turbine towers typically have a tubular pole or lattice structure configuration. Conventionally, the tubular pole configuration has been much easier to assemble than the lattice structure. However, tubular poles require the use of significantly more materials than lattice tower structures, thereby making the use of such towers quite expensive. Thus, it is often desirable to utilize lattice structures for supporting a wind turbine. Unfortunately, due to the number of components included within a lattice tower structure and the numerous joints that must be formed between the adjacent tower components, the assembly of a lattice tower structure is often quite complex and time consuming.

Accordingly, an improved system and method for assembling wind turbine tower components for use within an open, lattice tower structure would be welcomed in the technology.

BRIEF DESCRIPTION OF THE INVENTION

In one aspect, the present subject matter is directed to a system for assembling a tower section of a lattice tower structure for a wind turbine, wherein the tower section includes a plurality of support legs and at least one secondary support member coupled between each adjacent pair of support legs. The system may generally include a tower assembly fixture having a plurality of radially extending fixture arms, wherein each fixture arm extends between a first end and a second end. In addition, the system may include a plurality of trolleys. Each trolley may include a base frame configured to be coupled to a respective one of the fixture arms between its first and second ends and a leg mount pivotally coupled to the base frame. The leg mount may be configured to be coupled to a bottom end of a respective one of the support legs such that, when each of the support legs is coupled to its respective leg mount, the support legs are supported above the tower assembly fixture at a substantially vertical orientation.

In another aspect, the present subject matter is directed to a system for assembling a lattice tower structure for a wind turbine. The system may generally include a plurality of support legs and a plurality of secondary support members configured to be assembled together to form a tower section of the lattice tower structure. The system may also include a tower assembly fixture having a plurality of radially extending fixture arms, wherein each fixture arm extends between a first end and a second end. In addition, the system may include a plurality of trolleys. Each trolley may include a base frame configured to be coupled to a respective one of the fixture arms between its first and second ends and a leg mount configured to be coupled to a bottom end of a respective one of the support legs such that, when each of the support legs is coupled to its respective leg mount, the support legs are supported above the tower assembly fixture at a substantially vertical orientation so as to allow at least one secondary support member of the plurality of secondary support members to be installed between each adjacent part of support legs.

In a further aspect, the present subject matter is directed to a fixture trolley for use in assembling a tower section of a lattice tower structure for a wind turbine onto a tower assembly fixture. The trolley may generally include a base frame configured to be coupled to the tower assembly fixture and a leg mount pivotally coupled to the base frame. The leg mount may be configured to be coupled to a bottom end of a support leg of the tower section such that, when the support leg is coupled to the leg mount, the support leg is supported above the tower assembly fixture at a substantially vertical orientation.

DETAILED DESCRIPTION OF THE INVENTION

In general, the present subject matter is directed to an improved system and method for assembling tower sections of a lattice tower structure for a wind turbine. In several embodiments, the system may include a tower assembly fixture and a plurality of trolleys configured to be installed onto the fixture. As will be described below, the fixture may include a plurality of radially extending fixture arms, with each fixture arm being configured to have at least one trolley installed thereon. In a particular embodiment, each trolley may include a base frame configured to be coupled to its corresponding fixture arm and a leg mount configured to be coupled to a support leg of the tower section being assembled on the fixture. The various support legs of the tower section may be coupled to the leg mounts of the trolleys such that each support leg is supported above the fixture at a substantially vertical orientation so as to allow one or more secondary support members of the tower structure (e.g., circumferential spacers and/or cross-bracing members) to be installed between each pair of adjacent support legs in order to complete the assembly of the tower section.

As will be described below, in several embodiments, each trolley may be configured to be removably coupled to its respective fixture arm such that the trolley may be installed at a plurality of different radial locations along the fixture arm. Such adjustment of the radial position of each trolley may allow for tower sections having differing radial dimensions to be assembled on the tower assembly fixture. Moreover, in one embodiment, the leg mount of each trolley may be pivotally coupled to its corresponding base frame. Such a pivotal connection may allow the angular orientation of the leg mount to be adjusted, thereby providing a means for supporting the support legs at plurality of different substantially vertical orientations.

Referring now to the drawings,FIG. 1illustrates a perspective view of one embodiment of a wind turbine30. As shown, the wind turbine30generally includes a tower32extending from a tower support surface or foundation34(e.g., the ground, a concrete pad or any other suitable support surface). In addition, the wind turbine30may also include a nacelle36mounted on the tower32and a rotor38coupled to the nacelle36. The rotor38includes a rotatable hub40and at least one rotor blade42coupled to and extending outwardly from the hub40. For example, in the illustrated embodiment, the rotor38includes three rotor blades42. However, in an alternative embodiment, the rotor38may include more or less than three rotor blades42. Each rotor blade42may be spaced about the hub40to facilitate rotating the rotor38to enable kinetic energy to be transferred from the wind into usable mechanical energy, and subsequently, electrical energy. For instance, the hub40may be rotatably coupled to an electric generator (not shown) positioned within the nacelle36to permit electrical energy to be produced.

In several embodiments, the tower32may include a plurality of structural members (e.g., vertical, horizontal and/or diagonally extending structural members) coupled to one another so as to form an open lattice tower structure50. Such lattice tower structures50are also referred to in the art as “space fame” towers. In addition, the tower32may also include a cladding material52installed onto the lattice tower structure50so as to completely or substantially completely cover the open structure. The cladding material52may generally correspond to any suitable material, including various metal materials and/or fabrics (e.g., PVC-coated fabrics and/or PTFE-coated fabrics). As is generally understood, the cladding material52may, in one embodiment, be formed in sheets, with each sheet being configured to be installed onto or over specific portions of the lattice structure50. For instance, when the cladding material52corresponds to a fabric, the sheet of cladding material52may be configured to be unrolled onto or over a portion of a specific vertical section of the lattice structure50.

Referring now toFIG. 2, a side view of the tower32shown inFIG. 1is illustrated in accordance with aspects of the present subject matter, particularly illustrating the lattice tower structure50with the cladding material52completely removed therefrom. As indicated above, the lattice tower structure50may include a plurality of structural members configured to be coupled to one another so as to form the open, “space frame” arrangement. For example, the lattice tower structure50may include a plurality of substantially vertically oriented support members54(hereinafter referred to as “support legs” or simply “legs”) coupled one on top of the other so as to form the overall vertical shape or profile of the tower structure50. In addition, the lattice tower structure50may include a plurality of secondary support members56,58coupled between the support legs54, such as a plurality of horizontally oriented support members56(e.g., circumferential spacers and/or cladding brackets) and/or a plurality of diagonally orientated support members58(e.g., cross-bracing members).

In several embodiments, the lattice tower structure50may be formed by stacking a plurality of vertical tower sections one on top of the other. For instance, in the illustrated embodiment, the lattice tower structure50includes twelve vertical tower sections, namely a first (or top) tower section60, a second tower section62, a third tower section64, a fourth tower section66, a fifth tower section68, a sixth tower section70, a seventh tower section72, an eighth tower section74, a ninth tower section76, a tenth tower section78, an eleventh tower section80and a twelfth (or bottom) tower section82, stacked one on top of the other. Each vertical tower section may include its own set of support legs54and corresponding secondary support members56,58coupled between the legs54, with the support legs54of each tower section being coupled end-to-end with the support legs54of adjacent tower sections. As will be described below, one or more of the tower sections may be assembled individually and/or in combination with one or more other tower sections (e.g., to form a vertical stack of tower sections) using a tower assembly fixture102(FIGS. 4 and 5) located separate from a final tower location44of the wind turbine tower32(i.e., the location of the tower foundation34). The individual tower section(s) (or the stacked tower sections) may then be moved to the final tower location44and stacked together to form the complete lattice tower structure50.

For instance, in a particular embodiment of the present subject matter, the tower sections (less the top and bottom tower sections60,82) may be assembled into separate vertical stacks, with each vertical stack including two adjacent tower sections. Specifically, as shown inFIG. 2, the tower sections may be assembled into five separate vertical stacks, namely a first vertical stack84including the tenth and eleventh tower sections78,80, a second vertical stack86including the eighth and the ninth tower sections74,76, a third vertical stack88including the sixth and seventh tower sections70,72, a fourth vertical stack90including the fourth and fifth tower sections66,68and a fifth vertical stack92including the second and third tower section62,64. In such an embodiment, the various vertical stacks may be assembled at a separate location and subsequently stacked or installed one on top of the other above the bottom tower section82in a sequential manner. Thereafter, the top tower section60may the installed on top of the fifth vertical stack92(e.g., on top of the second tower section72) to form the complete lattice tower structure50.

It should be appreciated that, although the lattice tower structure50is shown in the illustrated embodiment as including twelve tower sections, the lattice structure50may generally include any suitable number of tower sections. For instance, in alternative embodiments, the lattice structure50may include less than twelve tower sections or greater than twelve tower sections.

It should also be appreciated that, as described herein, the various support legs54included within each tower section may be configured to be assembled within the lattice tower stricture50so as to have a substantially vertical orientation. As used herein, the term “substantially vertical orientation” generally refers to a completely vertical orientation plus or minus an angular tolerance generally corresponding to the maximum taper angle of the lattice tower structure50being assembled. For instance, in one embodiment, the term “substantially vertical orientation” may correspond to a completely vertical orientation plus or minus an angular tolerance of less than about 20 degrees, such as an angular tolerance of less than about 15 degrees or less than about 10 degrees. For example, as shown in the illustrated embodiment, the support legs54included within the bottom, eleventh, tenth, ninth, eighth, seventh and sixth tower sections82,80,78,76,74,72,70are orientated relative to vertical at about a five degree angle so as to form the tapered lower section of the lattice tower structure50whereas the fifth, fourth, third and second tower sections68,66,64,62include support legs54oriented orientated relative to vertical at about a zero degree angle so as to form the non-tapered upper section of the lattice tower structure50. In addition, the support legs54included within the top tower section60are orientated relative to vertical at about a five degree angle so as to form the top tapered section of the lattice tower structure60. In such an embodiment, each of the support legs54shown inFIG. 2may be considered to have a substantially vertical orientation as assembled within the lattice tower structure50.

Referring now toFIG. 3, a perspective view of the bottom tower section82of the lattice tower structure50as installed at the final tower location44is illustrated in accordance with aspects of the present subject matter. As shown, the bottom tower section82may be configured to be assembled onto and/or installed directly within the tower foundation34. For instance, each support leg54of the bottom tower section82may be initially sunk down into or otherwise coupled to the tower foundation34so as to have a substantially vertical orientation, with one or more circumferential spacers (not shown) being coupled between adjacent support legs54to ensure proper spacing and/or orientation of the legs54relative to one another. Thereafter, any other suitable secondary support members of the bottom tower section82may be coupled between the support legs54. For instance, as shown inFIG. 3, a plurality of cross-bracing members58may be coupled between adjacent support legs54to provide increased stiffness and structural support to the bottom tower section82of the lattice tower structure50.

Once the bottom tower section82is installed at the final tower location44, the remaining tower sections may then be stacked on top of the bottom tower section82to fully assemble the tower structure50. Specifically, as indicated above, the remaining tower sections may be assembled at a separate location (either individually or in combination with one or more other tower sections) and subsequently lifted into position on top of the bottom tower section82(e.g., via a crane). For instance, referring to the embodiment of the lattice tower structure50shown inFIG. 2, the tenth and eleventh tower sections78,80may be assembled one on top of the other at a separate location to form the first vertical stack84. As will be described below with reference toFIG. 22, such vertical stack84may then be lifted via a crane94and placed directly on top of the bottom tower section82to allow the bottom tower section82to be coupled directly to the eleventh tower section80.

In accordance with aspects of the present subject matter, various embodiments, components and features of a system100(and related methods) for assembling one or more tower sections of a lattice tower structure for a wind turbine will now be described with reference toFIGS. 4-24. Specifically, as will be described below, the system100(and related methods) may allow for vertical tower sections of a lattice tower structure50to be assembled onto a tower assembly fixture positioned at a location separate from the final tower location44and subsequently stacked one on top of the other at the final tower location44to form the tower structure50. It is believed that such a system100(and related methods) may allow for a lattice tower structure50to be erected in more safe, efficient and/or effective manner than is currently provided with conventional systems (and related methods) for assembling wind turbine tower components.

Referring specifically toFIGS. 4 and 5, differing views of one embodiment a tower assembly fixture102that may be utilized in connection with the disclosed system100for assembling tower sections of a lattice tower structure50are illustrated in accordance with aspects of the present subject matter. Specifically,FIG. 4illustrates a perspective view of the fixture102, with various components of the fixture102being exploded therefrom. In addition,FIG. 5illustrates another perspective view of the fixture102, with additional system components being installed thereon.

As shown, the tower assembly fixture102may generally include a plurality of fixture arms104extending radially outwardly from a central framed portion106. In general, each fixture arm104may be configured to extend radially between a first end108terminating at the central framed portion106and an opposite second end110positioned radially outwardly from the first end108. In several embodiments, the first end108of each fixture arm104may be configured to be coupled to the first ends108of adjacent fixture arms104so as to define the central framed portion106of the fixture102. For example, as shown inFIG. 4, each fixture arm104may include a circumferentially extending frame member112(e.g., a beam) positioned at its first end108. By coupling the frame members112of adjacent fixture arms104end-to-end, the assembled frame members112may form a frame-like structure that defines the central framed portion106of the fixture102. In one embodiment, the frame members112may be configured to be pivotally coupled to one another (e.g., via a pinned connection) to allow the circumferential spacing between the fixture arms104to be adjusted when coupling the arms104to one another.

Additionally, each fixture arm104may include one or more support beams114,116extending radially between its first and second ends108,110. For instance, as shown in the illustrated embodiment, each fixture arm104includes a first support beam114and a second support beam116extending directly between its first and second ends108,110, with the support beams114,116being coupled together via one or more cross beams118extending circumferentially therebetween. The support beams114,116may generally correspond to the primary structural components for the fixture102. For example, as will be described below, one or more fixture trolleys120may be mounted to and/or supported by the support beams114,116of each fixture arm104.

As particularly shown in the illustrated embodiment, the fixture102includes five fixture arms104, one for each support leg54configured to form part of each pentagonal-shaped vertical tower section of the disclosed lattice tower structure50. However, in other embodiments, the tower assembly fixture102may include any other suitable number of fixture arms104extending radially outwardly from the central framed portion106, such as less than five fixture arms or greater than five fixture arms, with such number corresponding to or differing from the number of support legs54configured to be installed within each tower section. As such, the disclosed fixture102may be configured to allow tower sections having any suitable shape (e.g., triangular, square, hexagonal, etc.) to be assembled thereon.

In several embodiments, prior to assembling the fixture arms104, a plurality of base or fixture pads122may be placed along the ground at the anticipated locations of the fixture arms104. Specifically, as shown inFIG. 4, fixture pads122may be installed on the ground at spaced apart locations along the anticipated radial footprint of each fixture arm104. Thereafter, the fixture arms104may be placed on top of the pads122and subsequently coupled to one another. Such fixture pads122may generally be configured to assist in preventing shifting or disruption of the underlying ground during assembly of the tower section(s) of the lattice tower structure50onto the tower assembly fixture102, thereby maintaining a level, planar surface for the fixture102.

Additionally, as shown inFIG. 4, circumferential spacers124may also be configured to be coupled between adjacent fixture arms104as the fixture arms104are being assembled to ensure proper circumferential positioning of the arms104relative to one another. In several embodiments, the circumferential spacers124may correspond to temporary components of the fixture102that are configured to be removed during final assembly thereof. For instance, in one embodiment, the circumferential spacers124may be configured to be maintained in place while suitable tensioning rods126are installed between the fixture arms104. Specifically, as shown inFIG. 4, one or more tensioning rods126may be installed between each pair of adjacent fixture arms104so as to provide a permanent means for maintaining the relative positioning of the fixture arms104. In such an embodiment, once the tensioning rods126are installed, the circumferential spacers124may be removed from the fixture102. Alternatively, the circumferential spacers124may be maintained between the fixture arms104following installation of the tensioning rods126(or may be used as an alternative to the tensioning rods126for maintaining proper spacing between the arms104).

Moreover, as shown inFIG. 5, the tower assembly fixture102may also include one or more radially extending platforms128configured to be installed along the side(s) of each fixture arm104. The platforms128may generally correspond to walking platforms for providing service personnel a stable walking area adjacent to each fixture arm104. As shown in the illustrated embodiment, one or more platforms128are installed along both sides of each fixture arm104. However, in other embodiments, a platform(s)128may only be installed along a single side of each fixture arm104.

Additionally, as shown inFIG. 5, one or more trolleys120may be configured to be installed onto each fixture arm104. As will be described below, each trolley102may be configured to be removably coupled to its corresponding fixture arm104at a plurality of different radial locations along the length of the fixture arm104. Such adjustable positioning of the trolleys120relative to the fixture arms104may allow the fixture102to be utilized when assembling tower sections having differing radial dimensions. As shown inFIG. 5, a single trolley120is installed onto each fixture arm104. However, as will be described below with reference toFIG. 17, two or more trolleys120may be installed onto each fixture arm104to allow two or more tower sections to be assembled on the fixture102simultaneously.

Referring now toFIG. 6, a side view of one of the fixture arms104described above with reference toFIGS. 4 and 5is illustrated in accordance with aspects of the present subject matter, particularly illustrating a trolley120installed on the fixture arm104as well as the various radial locations that the trolley120may be moved along the length of the fixture arm104. As shown, the trolley120may generally include a base frame130configured to be removably coupled to the fixture arm104and a leg mount132pivotally coupled to the base frame130that is configured to be secured to one of the support legs54included within the tower section being assembled onto the fixture102.

In general, the base frame130of the trolley120may be configured to be removably coupled to the support beam(s)116,118of the fixture arm104using any suitable attachment means known in the art. For instance, as shown in the illustrated embodiment, mechanical fasteners134(e.g., bolts, pins and/or the like) may be utilized to couple each corner of the base frame130(only two corners being shown inFIG. 6) to the support beams116,118(only one of which is shown). Alternatively, any other suitable attachment means may be utilized to removably couple the base frame130to the support beams116,118, such as clamps, brackets, fixture devices and/or any other suitable attachment devices.

As indicated above, by configuring the base frame130to be removably coupled to the support beams116,118, the trolley120may be moved radially along the length of the fixture arm104to allow tower sections having differing radial dimensions to be assembled on the fixture102. For instance, as shown in the illustrated embodiment, the trolley120may be installed at seven different radial locations defined along the length of the fixture arm104between its first and second ends108,110, namely a first radial location136, a second radial location138, a third radial location140, a fourth radial location142, a fifth radial location144, a sixth radial location146and a seventh radial location148. Thus, depending on the radial dimension of the particular tower section that is being assembled on the fixture104, the trolleys120may be positioned at the appropriate radial location on the fixture arms104for assembling such tower section. For example, referring to the embodiment of the lattice tower structure50shown inFIG. 2, the trolleys120may be positioned at the seventh radial location148to allow the eleventh tower section80to be assembled on the fixture102. Similarly, the trolleys120may be positioned at the sixth, fifth, fourth, third and second radial locations146,144,142,140,138to allow the tenth, ninth, eighth, seventh and sixth tower sections78,76,74,72,70, respectively, to be assembled on the fixture102. Moreover, given that the top, second, third, fourth and fifth tower sections60,62,64,66,68all define the same radial dimension at their bottom ends, the trolleys120may be positioned at the first vertical location136to assemble such tower sections onto the fixture102.

It should be appreciated that, in alternative embodiments, the trolleys120may be configured to be positioned at any other suitable number of radial locations along the length of each fixture arm104. Such number may, in several embodiments, generally depend on the number of tower sections desired to be assembled on the fixture102that have differing radial dimensions.

Moreover, as indicated above, the leg mount132for each trolley120may be configured to be pivotally coupled to its corresponding base frame130. Such a pivotal connection may allow for the angle of orientation of the leg mount132to be adjusted, as needed, to accommodate the differing vertical orientations of the legs54used across the various tower sections. For instance, in one embodiment, to assemble the top, sixth, seventh, eighth, ninth, tenth and eleventh tower sections60,70,72,74,76,78,80, the leg mount132may be required to be oriented at a first angle relative to vertical (e.g., about five degrees) whereas, to assemble the second, third, fourth and fifth tower sections62,64,66,68, the leg mount132may be required to be oriented at a different, second angle relative to vertical (e.g., about zero degrees).

Referring now toFIGS. 7 and 8, perspective views showing differing stages of a vertical tower section being assembled on the disclosed fixture102are illustrated in accordance with aspects of the present subject matter. Specifically,FIGS. 7 and 8illustrate the eleventh tower section80being assembled onto the fixture102, withFIG. 7showing various tower components of such tower section80being exploded away from the fixture102.

As shown, to assemble the eleventh tower section80, the trolleys120may be initially positioned at the appropriate radial location along the fixture arms104so as to accommodate the specific radial dimension of the tower section80. For instance, each tower section may define a radial dimension150(FIG. 7) as measured between the center of the tower section and a bottom end96of each support leg54. As shown, in the illustrated embodiment, the eleventh tower section80generally defines a radial dimension that requires the trolleys120to be positioned at the radially outermost location along the fixture arms104(e.g., at the seventh radial location148). In addition, the angular orientation of the leg mounts132may be adjusted, as necessary, to ensure that each leg mount132is positioned at the proper orientation associated with the eleventh tower section80(e.g., about 5 degrees).

Thereafter, as shown inFIG. 7, the bottom end96of each support leg54of the tower section80may then be mounted to one of the trolleys120, with circumferential spacers56being installed between adjacent legs54(e.g., at the top ends98of the legs54) to ensure proper circumferential positioning. Once all of the support legs54have been installed onto the fixture102, suitable cross-bracing members58may be coupled between each pair of adjacent legs544. For instance, as shown inFIG. 8, four cross-bracing members58(e.g., forming two “X-shapes”) may be installed between each pair of adjacent support legs504. Thereafter, the circumferential spacers56may, in one embodiment, be removed from the assembled tower section80.

Alternatively, the circumferential spacers56and/or the cross-bracing members58may be pre-installed between adjacent pairs of support legs54. In such an embodiment, each support leg54of the assembled pair of support legs54may then be mounted onto the trolleys120at the same time.

It should be appreciated that the various other vertical tower sections may be similarly assembled onto the fixture102. For example, to assemble each of the tenth, ninth, eighth, seventh and sixth tower sections78,76,74,72,70, the trolleys120may be initially moved to the appropriate radial location associated with the tower section being assembled. Thereafter, the support legs54for the tower section may be mounted to the trolleys120, with circumferential spacers56being installed between each pair of adjacent legs54. The cross-bracing members58may then be installed between the support legs54to complete the assembly.

It should also be appreciated that, as an alternative to assembling each tower section on the fixture102individually, the tower sections may be assembled one on top of the other on the fixture102to form a stack of two or more tower sections. Specifically, as indicated above, it may be desirable to assemble pairs of tower sections together on the fixture102, with the resulting vertical tower stack then being transferred over to the final tower location44for final assembly within the lattice tower structure50. For example,FIG. 9illustrates a perspective view of the eleventh and tenth tower sections80,78assembled together on the fixture102to form the first vertical stack84. In such an embodiment, the eleventh tower section80may be initially assembled on the fixture102as described above with reference toFIGS. 7 and 8. Thereafter, the tenth tower section78may be assembled on top of the eleventh tower section80by coupling the bottom ends96of its support legs54to the top ends98of the support legs54of the eleventh tower section80, with suitable circumferential spacers56being installed between the adjacent legs54of the tenth tower section78to maintain proper positioning. The cross-bracing members58may then be installed, as desired, between the adjacent legs54of the tenth tower section78.

By assembling a vertical stack of two or more tower sections on the fixture102, the stack may then be transferred as a whole to the final tower location44of the lattice tower structure50for final assembly. For example,FIG. 22illustrates a perspective view of the vertical stack84shown inFIG. 9being lowered down onto the bottom tower section82of the lattice tower structure50shown inFIG. 3. Specifically, a crane94or other suitable lifting device may be used to lift the vertical stack84from the fixture102and transport the stack84to the final tower location44. The stack84may then be lowered into place to allow the adjacent tower sections to be coupled to one another. For instance in the illustrated embodiment, the bottom ends96of the support legs54of the eleventh tower section80may be coupled to the top ends98of the support legs54of the bottom tower section82.

It should be appreciated that, similar to the vertical stack84shown inFIG. 9, various other tower sections may be assembled together to form a vertical stack that may then be lifted up and installed at the final tower location. For instance, as indicated above with reference toFIG. 2, a second vertical stack86may be formed by stacking the eighth and ninth tower sections74,76on the fixture102and a third vertical stack88may be formed by stacking the sixth and seventh tower sections70,72on the fixture102. Similarly, a fourth vertical stack90may be formed by stacking the fourth and fifth tower sections66,68on the fixture102while a fifth vertical stack92may be formed by stacking the second and third tower section62,64on the fixture102.

It should also be appreciated that, in several embodiments, some or all of the circumferential spacers56utilized during the assembly process to ensure proper circumferential spacing of the legs54may also function as cladding brackets. In such embodiments, the cladding brackets may be maintained on the tower section(s) to allow the cladding material52to be coupled to the resulting lattice tower structure50. For instance, in one embodiment, circumferential spacers56doubling as cladding brackets may be installed between the adjacent legs54of every other tower section (e.g., the even-numbers tower sections) to allow the cladding material52to be coupled thereto. Thus, in the embodiment shown inFIG. 9, the circumferential spacers56shown at the top of the tenth tower section78may, for example, correspond to suitable cladding brackets for the latter tower structure50.

Referring now toFIG. 10, another perspective view showing a tower section being assembled on the disclosed tower assembly fixture102is illustrated in accordance with aspects of the present subject matter. Specifically,FIG. 10illustrates the fifth tower section68being assembled onto the fixture102, with various tower components of such tower section68being exploded away from the fixture10.

As shown, to assemble the fifth tower section68, the trolleys120may be initially positioned at the appropriate radial location along the fixture arms104so as to accommodate the specific radial dimension of the tower section68. For instance, as shown inFIG. 10, the fifth tower section68generally defines a radial dimension that requires the trolleys120to be positioned at the radially innermost location along the fixture arms104(e.g., at the first radial location136). In addition, the angular orientation of the leg mounts132may be adjusted, as necessary, to ensure that each leg mount132is positioned at the proper orientation associated with the fifth tower section68(e.g., about zero degrees).

Thereafter, as shown inFIG. 10, the support legs54of the tower section68may then be mounted to each trolley120, with circumferential spacers56being installed between adjacent legs54to ensure proper circumferential positioning. Once all of the support legs54have been installed onto the fixture102, suitable cross-bracing members58may be coupled between each pair of adjacent legs54. For instance, as shown inFIG. 10, eight cross-bracing members58(e.g., forming four “X-shapes”) may be installed between each pair of adjacent support legs54. Thereafter, the circumferential spacers56may, in one embodiment, be removed from the assembled tower section.

As indicated above, in several embodiments, the fourth, third and second tower sections66,64,62may all define the same or substantially the same radial dimension as the fifth tower section68with respect to the position of the bottom ends96of each of their support legs54relative to the center of each tower section. As a result, such tower sections may be similarly assembled onto the fixture102without having to adjust the radial positioning of the trolleys120along the fixture arms104. For example, to assemble each of the fourth, third, and second tower sections66,64,62, the support legs54for each tower section may be mounted to the trolleys102, with circumferential spacers56being installed between each pair of adjacent legs54. The cross-bracing members58may then be installed between the support legs54to complete the assembly.

Additionally, as indicated above, the tower sections may be configured to be assembled one on top of the other on the fixture102to form a stack of two or more tower sections. For example,FIG. 11illustrates a perspective view of the fifth and fourth tower sections68,66assembled together on the fixture to form the fourth vertical stack90. In such an embodiment, the fifth tower section68may be initially assembled on the fixture102in the manner described above with reference toFIG. 10. Thereafter, the fourth tower section66may be assembled on top of the fifth tower section68by coupling the bottom ends96of its support legs54to the top ends98of the support legs54of the fifth tower section68, with suitable circumferential spacers56being installed between the adjacent legs54of the fourth tower section66to maintain proper positioning. The cross-bracing members58may then be installed, as desired, between the adjacent legs54of the fourth tower section66. The resulting vertical stack90may then be lifted off of the fixture102via a crane and transported to the final tower location44for assembly on top of the previously installed tower section(s). For instance, referring to the embodiment shown inFIG. 2, the fourth vertical stack80formed by the fourth and fifth tower sections66,68may be installed at the final tower location44by coupling the bottom ends96of the support legs54of the fifth tower section68to the top ends98of the support legs54of the previously installed sixth tower section70.

Referring now toFIG. 12, another perspective view showing a tower section assembled on the disclosed tower assembly fixture102is illustrated in accordance with aspects of the present subject matter. Specifically,FIG. 12illustrates the top tower section60as assembled onto the fixture102.

As shown, the top tower section60may be assembled onto the tower assembly fixture102in a manner similar to that described above with reference toFIG. 10for the fifth tower section68. Specifically, the trolleys120may be initially positioned at the radially innermost location along the fixture arms104(e.g., at the first radial location136) and the angular orientation of the leg mounts132may be adjusted, as necessary, to ensure that each leg mount132is positioned at the proper orientation associated with the support legs54of the top tower section60(e.g., about five degrees). Thereafter, the support legs54of the tower section60may be mounted to each trolley120, with circumferential spacers56being installed, as necessary, between adjacent legs54to ensure proper circumferential positioning. Once the support legs54have been installed onto the fixture102, suitable cross-bracing members58may be coupled between each pair of adjacent legs54. For instance, as shown inFIG. 12, ten cross-bracing members58(e.g., forming five “X-shapes”) may be installed between each pair of adjacent support legs54. Additionally, as shown inFIG. 12, an uptower support assembly152may also be installed on top of the support legs54of the top tower section60. As is generally understood, the uptower support assembly152may be configured to support the various uptower components of the wind turbine40shown inFIG. 1. For instance, the nacelle36(FIG. 1) may be mounted directly on top of the uptower support assembly152.

Referring now toFIGS. 13-16, several different views of one of the fixture trolleys120described above are illustrated in accordance with aspects of the present subject matter. Specifically,FIG. 13illustrates a perspective view of the trolley120andFIGS. 14 and 15illustrate side views of the trolley120, particularly illustrating the leg mount132of the trolley120at different angular orientations relative to its base frame130. Additionally,FIG. 16illustrates a partial perspective view of a top portion of the trolley120shown inFIG. 13, with the bottom end96of a support leg54being coupled to the leg mount132of the trolley120.

As particularly shown inFIG. 13, the base frame130may generally include a first sidewall154, a second sidewall156spaced apart from the first sidewall154and a bottom wall158extending between the first and second sidewalls154,156. In several embodiments, each sidewall154,156may include a pair of mounting brackets160extending outwardly therefrom for receiving suitable attachment devices for coupling the trolley120to its corresponding fixture arm104. For instance, as indicated above, mechanical fasteners134, such as bolts, pins and/or the like, may be utilized to couple the trolley120to its fixture arm104. In such an embodiment, a fastener134may be inserted through each mounting bracket160and coupled to one of the support beams114,116of the adjacent fixture arm104(e.g., via a nut) to allow the trolley120to be coupled to the fixture arm104.

Additionally, as shown inFIGS. 13-15, the leg mount132may be configured to be coupled between the opposed sidewalls154,156of the base frame130such that a portion of leg mount132extends vertically within a cavity defined between the first and second sidewalls154,156. As indicated above, in several embodiments, the leg mount132may be configured to be pivotally coupled to the base frame130. For instance, as shown inFIGS. 13-15, an opening162may be defined in each sidewall154,156that is configured to receive a corresponding projection164extending outwardly from each side of the leg mount132. Such a pinned or pivotal connection may provide a means for pivoting or rotating the leg mount132about a pivot axis166(FIG. 13) extending through the center of the openings162defined in the sidewalls154,156, thereby allowing for the angular orientation of the leg mount132to be adjusted relative to the base frame130. It should be appreciated that, in other embodiments, the pivotal connection provided between the leg mount132and the base frame130may be achieved using any other suitable means and/or configuration that allows for the angular orientation of the leg mount132to be adjusted relative to the base frame130.

Moreover, as shown in the illustrated embodiment, the trolley120may also include an angle adjustment device168coupled between the base frame130and the leg mount132for adjusting the angular orientation of the leg mount130. Specifically, as shown inFIGS. 13-15, the angle adjustment device168corresponds to a screw jack including a jack portion170coupled the base frame130and a screw portion172coupled to a bottom end of the leg mount132. In such an embodiment, by linearly actuating the screw portion172(e.g., by turning a wheel174associated with the jack portion170), the angular orientation of the leg mount132relative to the base frame130may be adjusted. For instance, as shown inFIG. 14, by linearly actuating the screw portion172in a first direction (as indicated by arrow174), the leg mount132may be rotated relative to the base frame130about the rotational axis in a first rotational direction (as indicated by arrow178). Similarly, as shown inFIG. 15, by linearly actuating the screw portion172in a second, opposite direction (as indicated by arrow180), the leg mount132may be rotated relative to the base frame130about the rotational axis in a second, opposite rotational direction (as indicated by arrow182).

As shown inFIGS. 14 and 15, in one embodiment, the base frame132may include pivot stops184,186positioned both forward and aft of the leg mount132that serve to limit the movement of the leg mount132relative to the base frame130. Specifically as shown inFIG. 14, the screw portion172may be linearly actuated in the first direction176until the leg mount132contacts a first pivot stop184positioned aft of the leg mount132. Additionally, as shown inFIG. 15, the screw portion172may be linearly actuated in the second direction180until the leg mount132contacts a second pivot stop186positioned forward of the leg mount132. As a result, the first and second pivot stops184,186may generally define an angular range of travel188across which the leg132mount may be pivoted relative to the base frame130.

Additionally, in several embodiments, the trolley120may also include an angle indicator for providing an indication of the angular orientation of the leg mount132relative to the base frame130. Specifically, as shown inFIGS. 13-15, in one embodiment, an angle marker190may be coupled to one of the projections164extending through the openings162defined in the sidewalls154,156such that the angle marker190is positioned along an exterior surface of the base frame130. Additionally, as shown in the illustrated embodiment, an angle reference guide191may be provided on the exterior surface of the base frame130adjacent to the angle marker190. The angle reference guide191may, for example, include markings, numbers and/or any other suitable feature(s) that provide an indication of the angular orientation of the leg mount132. As such, when the leg mount132is pivoted relative to the base frame130, the orientation of the angle marker190relative to the angle reference guide191may be referenced to allow a service worker to quickly and easily determine the current angular orientation of the leg mount132.

As indicated above, the leg mount132may be configured to be coupled to the bottom end96of one of the support legs54of the tower section being assembled onto the tower assembly fixture102. As such, the leg mount132may be configured to and/or may include any suitable components and/or features configured to accommodate securing the bottom end96of a support leg54thereto. For instance, as shown inFIG. 16, in one embodiment, each support leg54may correspond to a substantially “U-shaped” support beam having first and second sidewalls192,193and an outer wall194extending between the sidewalls192,193. In such an embodiment, a widthwise dimension of a top portion195of the leg mount132may be designed to be less than a corresponding width of the gap defined between the sidewalls192,193at the bottom end96of the support leg54such that the top portion195of the leg mount132may be received within the “U-shaped” channel defined by the support leg64.

Additionally, the leg mount132may also include one or more mounting plates196,197,198for coupling the leg mount to the bottom end of the support leg. For instance, as shown in the illustrated embodiment, the leg mount132includes an outer mounting plate196and first and second side mounting plates197,198extending substantially vertically from the top portion195of the leg mount132, with each mounting plate196,197,198including a plurality of mounting holes199(FIG. 13) for receiving suitable mechanical fasteners. In such an embodiment, when the top portion195of the leg mount132is received within the “U-shaped” channel defined by the support leg54, the first and second mounting plates197,198may be configured to extend adjacent to the inner surfaces of the first and second sidewalls192,193, respectively, of the support leg54while the outer mounting plate196may be configured to extend adjacent to the inner surface of the outer wall194. Mechanical fasteners may then be inserted through both the mounting holes199defined in the mounting plates196,197,198and corresponding openings (not shown) defined in the walls of the support leg54to allow the leg54to be coupled to the leg mount132.

Referring now toFIG. 17, a perspective view of an embodiment in which nested tower sections have been assembled onto the disclosed tower assembly fixture102is illustrated in accordance with aspects of the present subject matter. As shown inFIG. 17, as opposed to only installing a single trolley120onto each fixture arm104of the tower assembly fixture102, multiple trolleys120A,120B,120C may be installed onto the fixture arms104at different radial locations along the length of each arm104. As a result, tower sections having differing radial dimensions may be assembled simultaneously onto the fixture102in a nesting configuration, thereby further increasing the efficiency at which the lattice tower structure50may be installed at a wind turbine location.

In the illustrated embodiment, three trolleys have been installed onto each fixture arm104, namely a first trolley120A, a second trolley120B and a third trolley120C, with the trolleys120A,120B,120C being disposed at different radial locations along the length of each fixture arm104. Specifically, as shown inFIG. 17, each first trolley120A is installed onto its respective fixture arm104at the seventh radial location148defined on each fixture arm104, which may correspond to the radial location for assembling the eleventh tower section80onto the tower assembly fixture102. Similarly, each second trolley120B is installed onto its respective fixture arm104at the fifth radial location144, which may correspond to the radial location for assembling the ninth tower section76onto the fixture102. Moreover, each third trolley120C is installed onto its respective fixture arm104at the third radial location140, which may correspond to the radial location for assembling the seventh tower section72onto the fixture102.

As indicated above, by installing multiple trolleys120A,120B,120C onto each fixture arm104, the tower sections may be assembled onto the tower assembly fixture102in a nesting configuration. For example, as shown inFIG. 17, the seventh tower section72has been assembled onto the fixture102using the plurality of third trolleys120C. Additionally, although not shown, by assembling the seventh tower section72onto the fixture102, the sixth tower section70may then be assembled directly on top of the seventh tower section72to form the third vertical stack88. Moreover, as shown inFIG. 17, the ninth tower section76has been assembled onto the fixture102using the plurality of second trolleys120B so as to be positioned radially outwardly from the seventh tower section72, with the eighth tower section74being stacked on top thereof to form the second vertical stack86. Similarly, although not shown, the eleventh tower section80(and, optionally, the tenth tower section80stacked thereon) may also be assembled onto the fixture102using the plurality of first trolleys120B so as to be positioned radially outwardly from the ninth and eighth tower sections76,76. The nested tower sections (or nested vertical stacks) may then be removed individually from the fixture102for subsequent installation at the final tower location44.

Referring now toFIG. 18, a perspective view of one embodiment of a upend device200configured to facilitate upending the vertical legs54from a horizontal position on and/or adjacent to the ground for subsequent installation onto the tower assembly fixture102is illustrated in accordance with aspects of the present subject matter. As will be described below, the upend device200may allow a support leg54to be upended without damaging any components of the support leg54, such as any splice plates coupled to the bottom end96of the support leg54.

As shown, the upend device200may generally include a pivot tube202configured to provide a pivot point for rotating or pivoting a support leg54relative to the ground as it is being upended. Specifically, as will be described below, the pivot tube202may be configured to directly contact the ground so as to provide a means for allowing the bottom end96of each support leg54to be pivoted relative to the ground as the top end96of such support leg54is being lifted therefrom in order to upend the leg54. Additionally, as shown inFIG. 18, the upend device200may also include first and second pivot arms204,206extending outwardly from the pivot tube202so as to define a channel208between the pivot arms204,206for receiving the bottom end96of the support leg54. Specifically, in several embodiments, a portion of the outer wall194extending from the bottom end96of each support leg54may be configured to be inserted between the first and second pivot arms204,206such that the first pivot arm204is received within the “U-shaped” channel defined by the support leg54and extends adjacent to and/or contacts the inner surface of the outer wall194.

Moreover, the second pivot arm206may include a raised portion210configured to act as a mechanical stop for the bottom end96of each support leg54. Specifically, as will be described below, when a support leg54is received between the first and second pivot arms204,206, the bottom end96of the support leg54may abut against or otherwise contact the raised portion210of the second pivot arm206. In addition, the second pivot arm206may also include a roller212positioned outwardly from the raised portion210such that the roller212extends adjacent to and/or contacts the outer surface of the outer wall194of the support leg54when the bottom end96is engaged against the raised portion210.

Additionally, as shown inFIG. 18, the upend device200may also include a pivot stop arm214extending outwardly from the pivot tube202in a direction generally perpendicular to the first and second pivot arms204,206. The pivot stop arm214may generally be configured to stop the upend device200and the support leg54from being over rotated as the support leg54is being pivoted relative to the ground. Specifically, the pivot stop arm214may be configured to contact the ground once the support leg54has been rotated to a substantially vertical position, thereby preventing further rotation of the support leg54relative to the ground.

One embodiment of a method for using the upend device200to upend a support leg54will now be described below with referenceFIGS. 19-21. As shown inFIG. 19, the support leg54may be initially supported above the ground on first and second support stands216,218. The upend device200may then be installed onto the bottom end96of the support leg54. For instance, as shown inFIG. 19, the upend device200may be lifted (e.g., via a crane cable220) into position adjacent to the bottom end96of the support leg54and then moved lengthwise (e.g., as indicated arrow222) relative to the support leg54such that the bottom end96is received between the first and second pivot arms204,206. Specifically, as shown inFIG. 21, the upend device200may be moved relative to the support leg54until the bottom end96of the support leg54contacts the raised portion210of the second pivot arm206.

Thereafter, both the bottom end96of the support leg54and the upend device200may be lifted slightly (e.g., via the crane cable220) to allow the support stand adjacent to the bottom end96(e.g., the first support stand216) to be removed. The support leg54may then be supported relative to the ground via the upend device200and the remaining support stand (e.g., the second support stand218) as the crane cable220is removed from the upend device200and attached to the top end98of the support leg54. The top end98of the support leg54may then be lifted slightly using the crane cable220to allow the remaining support stand (e.g., the second support stand218) to be removed from the support leg54.

As shown inFIG. 20, after removal of the remaining support stand, the top end98of the support leg54may be lifted upward via the crane cable220as the bottom end96of the support leg54pivots relative to ground about the pivot tube202. The top end98of the support leg54may then continue to be lifted upward until the support leg54has been pivoted to a substantially vertical position and the pivot stop arm214is contacting the ground. The support leg54may then be lifted out of the upend device200and transported via the crane cable220to the location of the tower assembly fixture102for subsequent attachment to one of the trolleys120.

Referring now toFIGS. 23 and 24, a flow diagram of one embodiment of a method300for assembling a tower section of a lattice tower structure for a wind turbine is illustrated in accordance with aspects of the present subject matter. In general, the method300will be described herein with reference to the system100and related system components described above with reference toFIGS. 4-22. However, it should be appreciated by those of ordinary skill in the art that the disclosed method300may be implemented in accordance with any other suitable embodiment of system for assembling a tower section of a lattice tower structure. In addition, althoughFIGS. 23 and 24depict steps performed in a particular order for purposes of illustration and discussion, the methods discussed herein are not limited to any particular order or arrangement. One skilled in the art, using the disclosures provided herein, will appreciate that various steps of the methods disclosed herein can be omitted, rearranged, combined, and/or adapted in various ways without deviating from the scope of the present disclosure.

As shown inFIG. 23, at (302), the method300may include positioning at fixture pad(s) at each anticipated installation location of the fixture arms. Specifically, as described above with reference toFIG. 4, fixture pads122may be installed on the ground at spaced apart locations along the anticipated radial footprint of each fixture arm104. Thereafter, at (304), the method300may include positioning each fixture arm on top of the fixture pad(s) disposed at its anticipated installation location.

Additionally, at (306), the method300may include coupling each of the fixture arms together to form a tower assembly fixture. Specifically, as described above, the frame member112disposed at the first end108of each fixture arm104may be configured to be coupled to the frame members112of adjacent fixture arms104to assemble the arms104together. As such, the resulting tower assembly fixture102may include a central framed portion106and a plurality of fixture arms104extending radially outwardly from the central framed portion106.

Moreover, at (308), the method300may include coupling a circumferential spacer and/or a tensioning rod between each pair of adjacent fixture arms. For instance, as described above, in one embodiment, circumferential spacers124may be temporarily installed between adjacent fixture arms104to ensure proper circumferential positioning of the arms104relative to one another while suitable tensioning rods126are being installed between the fixture arms104. In such an embodiment, once the tensioning rods126have been installed, the circumferential spacers124may be removed from the fixture102.

Additionally, as shown inFIG. 23, at (310), the method300may include positioning a radially extending platform(s) along a side(s) of one or more of the fixture arms. As indicated above, such platform(s) may provide a walking surface for service personnel working on and/or around the tower assembly fixture102.

Referring particularly now toFIG. 24, at (312), the method300may include installing a trolley onto each fixture arm of the tower assembly fixture. For instance, as indicated above, the base frame130of each trolley120may be configured to be coupled to the support beam(s)114,116forming each radially extending fixture arm104.

Additionally, when installing the trolleys120onto the fixture arms102, the radial positioning of each trolley102and/or the angular orientation of the leg mount132of each trolley120may be considered in light of the specific tower section being assembled onto the tower assembly fixture102. Specifically, at (314), the method300may include adjusting, as necessary, the radial position of each trolley120along the radial length of its respective fixture arm104. For instance, as indicated above, each trolley120may be configured to be coupled to its respective fixture arm104at a plurality of different radial locations so as to accommodate tower sections having differing radial dimensions. Additionally, at (316), the method300may include adjusting, as necessary, an angular orientation of the leg mount132of each trolley120. For example, as described above, each trolley120may include an angle adjustment device168that allows the angular orientation of the leg mount132to be adjusted relative to the corresponding base frame130of the trolley120so as to match the angular orientation of the leg mount132to the desired substantially vertical orientation for the support legs54of the specific tower section being assembled.

Moreover, at (318), the method300may include securing the bottom end of each support leg to one of the trolleys. For example, as indicated above, the bottom end96of each support leg54may be configured to be coupled to the leg mount132of one of the trolleys120, thereby allowing the support leg54to be supported above the tower assembly fixture102at its desired substantially vertical orientation. Thereafter, one or more secondary support members may be configured to be coupled between each pair of adjacent support legs54. For instance, as shown inFIG. 24, at (320), the method300may include installing a circumferential spacer(s) between each pair of adjacent support legs. Moreover, at (322), the method300may include installing a cross-bracing member(s) between each pair of adjacent support legs.

In addition to the various method elements shown inFIGS. 23 and 24, the disclosed method300may also include any other suitable method elements consistent with disclosure provided herein. For instance, upon assembling a given tower section onto the tower assembly fixture102, another tower section may be assembled directly on top of the previously assembled section to form a vertical tower stack. In addition, two or more trolleys120may be installed onto each fixture arm104to allow two or more nested tower sections to be assembled onto the tower assembly fixture102. Moreover, once a given tower section (or vertical stack) has been assembled onto the tower assembly fixture102, the tower section (or vertical stack) may then be removed from the fixture102and transported to the final tower location44for subsequent assembly within the lattice tower structure50.