Patent Application
20100024311
The field of this disclosure relates generally to wind turbine assemblies, and more particularly to a mount for mounting the tower of such a wind turbine assembly on a foundation.
Wind turbines are increasingly used for the generation of electrical energy. A wind turbine typically comprises a rotor-driven turbine generator mounted atop a tower constructed of multiple tower sections that are stacked and secured together. These sections may be cylindrical, frusto-conical or other suitable shape, and may be generally solid, tubular, or lattice-type sections. For example, one conventional wind turbine assembly includes a tower in which the tower sections each comprise a single-piece cylindrical or frusto-conical wrought steel section. These sections are joined together to reach above ground a height sufficient to provide clearance for the turbine blades and to support the generator at an altitude where there are sufficient wind velocities for adequate power generation.
The lowermost tower section (often referred to as a base section) of the wind turbine assembly tower is secured to the foundation (e.g., a concrete slab or other suitable foundation). The diameter of each tower section, and in particular the base section must be large enough in cross-section (e.g., diameter) to withstand the aerodynamic loads produced by wind forces and gravitational loads that are imposed by the mass of the heavy turbine generator and the drive sections of the turbine. As wind turbine towers have become increasingly taller, the cross-sectional dimensions of the tower base section has created difficulties in the ground transportation (e.g., by truck or rail) of these base sections due to size limitations or roadways, bridges and tunnels through which these sections must pass in route to their assembly destination.
Wind turbine tower manufacturers have had to use other means, such as increasing the shell thicknesses of the sections or using guy wires, to hold smaller cross-sectioned towers in place and support the tower against the aerodynamic and structural loads encountered by the tower. While these measures have been helpful, they have their limits and have not sufficiently met the need for a wind turbine tower base section of a larger transverse cross-section that is also capable of ground transport.
In one aspect, a wind turbine assembly is provided that is configured for standing on a foundation. The wind turbine assembly includes a wind turbine generator, and a tower having an upper end and a lower end. The tower is configured to support the wind turbine generator generally adjacent the upper end of the tower. The wind turbine assembly also includes a tower mount for supporting the tower. The tower mount has an upper end and a lower end. The upper end of the tower mount is connectable with the lower end of the tower and the lower end of the tower mount is mountable on the foundation to secure the wind turbine assembly on the foundation. The tower mount is tubular and has a height and an outer transverse cross-sectional dimension that is substantially greater than the height of the tower mount. The tower mount includes a plurality of circumferential segments that are connectable in generally end-to-end relationship to form the tubular tower mount.
In another aspect, a tower mount is provided for mounting a wind turbine assembly on a foundation. The tower mount includes a plurality of circumferentially extending segments connectable in generally end-to-end relationship with each other so that the tower mount is generally tubular upon assembly thereof The tower mount has an upper end and a lower end and the upper end of the tower mount is connectable with the wind turbine assembly to support the wind turbine assembly on the tower mount. The lower end of the tower mount is mountable on the foundation to secure the wind turbine assembly and tower mount on the foundation. The tower mount is configured to withstand overturning moments.
In another aspect, a method of assembling a wind turbine is provided. The method includes providing a tower having a top end and a bottom end, and providing a nacelle and blades associated with the tower. The method also includes providing a segmented base ring to support the tower at a base of the tower.
Referring now to the drawings and in particular to
Tower 102 is suitably tubular, and in the illustrated embodiment it is annular and has an internal cavity (not shown) extending longitudinally within tower 102 from foundation 104 up to nacelle 106. Tower 102 generally comprises a plurality of individual tower sections 124 that are connectable to each other in a stacked, end-to-end (e.g., one on top of the other) relationship to form tower 102. Tower sections 124 may each be of generally constant transverse cross-sectional dimension (e.g., a constant diameter in the illustrated embodiment in which tower sections 124 are each generally annular), or one or more of tower sections 124 may be frusto-conical, and/or the transverse cross-sectional dimension of one or more of tower sections 124 may be constant but different from that of one or more of the other tower sections—such as in a stepped configuration in which the transverse cross-sectional dimension of each tower section 124 decreases as the sections are stacked toward to the top of tower 102.
As illustrated in
As seen in
As an example,
Upper end 128 of tower mount 127 is suitably configured for connecting (i.e., securing) tower 102 to tower mount 127. As an example, in the illustrated embodiment upper end 128 comprises a flange member 134 extending transversely inward relative to circumferential sidewall 132 and having a plurality of openings 165 for receiving suitable threaded fasteners (not shown) therethrough. A lower end of lowest section 124 of tower 102 has a corresponding plurality of openings (not shown) for alignment with openings in flange member 134 to permit securement of tower 102 to flange member 134 by the threaded fasteners (not shown) and corresponding nuts (not shown). It is contemplated that tower 102 may be connected to upper end 128 of tower mount 127 other than by threaded fasteners, such as by welding or other suitable connection, without departing from the scope of this invention. It is also understood that upper end 128 may be configured such that flange member 134 extends transversely outward from sidewall 132, or it may be configured (together with sidewall 132) as a T-flange similar to lower end 130 of tower mount 127.
With reference back to
At or adjacent circumferential ends 141 of each tower mount segment 135 an external connecting flange 137 is secured to and is more suitably formed integral (e.g., by casting) with the outer surface of sidewall 132 of tower mount 127. In the illustrated embodiment each connecting flange 137 is generally rectangular and extends at least in part, and in the illustrated embodiment entirely, vertically along sidewall 132. It is understood, however, that connecting flange 137 may be other than rectangular without departing from the scope of this invention. Illustrated connecting flange 137 also suitably extends along sidewall 132 substantially the entire height of sidewall 132 from upper end to lower end of tower mount 127. In an alternative embodiment, connecting flange 137 extends less than the entire height of tower mount 127.
Openings 139 are disposed in each connecting flange 137 in spaced relationship along the length of the flange. Connecting flanges 137 and openings 139 arc located and sized substantially the same for each circumferential segment 135 of tower mount 127. As such, upon placement of segments 135 in circumferential end-to-end relationship to form tower mount 127, openings 139 of adjacent connecting flanges 137 are aligned with each other to receive suitable threaded fasteners therethrough as illustrated in
To sufficiently handle shear stress on connecting flanges 137, fillets (not shown) of suitable radii are formed where connecting flanges 137 join sidewall 132. In one suitable embodiment, the fillet radii are suitably in the range of about 10 mm to about 30 mm, and more suitably about 25 mm. It is understood, however, that the fillet radii may be other than as set forth above, depending on necessary stresses to be withstood (with reduced stress generally accompanying larger fillet radii), and remain within the scope of this invention.
Tower mount 127 in one embodiment is suitably constructed of steel. For example, tower mount 127 may suitably comprise ASTM A36 steel and derivatives thereof Other suitable materials may be used to make tower mount 127, however, without departing from the scope of this invention. More suitably, tower mount segments 135 (i.e., upper end 128, lower end 130, sidewall 132, and connecting flanges 137 including fillets joining sidewall 132 with connecting flanges 137) are each formed integrally and even more suitably are formed by casting. Casting in this manner provides both cost and design advantages over other fabrication techniques. It is understood, though, that other suitable fabrication techniques and methods may be used to make tower mount segments 135 without departing from the scope of this invention.
With reference now to
When introducing elements of the present invention or preferred embodiments thereof, the articles “a”, “an”, “the”, and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including”, and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
As various changes could be made in the above constructions and methods without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
