The subject matter described herein relates generally to wind turbines and, more particularly, to a support tower for use with a wind turbine.
At least some known wind turbines include a nacelle fixed atop a tower. The nacelle includes a rotor assembly coupled to a generator through a shaft. In known rotor assemblies, a plurality of blades extend from a rotor. The blades are oriented such that wind passing over the blades turns the rotor and rotates the shaft, thereby driving the generator to generate electricity.
At least some known wind turbines include lattice-type support towers that include a plurality of vertical support legs, cross beams, and joints that couple the cross beams to the vertical support legs. At least some known lattice-type support towers include open frame vertical support legs that are subject to large cyclic loading, which results in a large displacement of leg members and increased bending stresses and torsional stresses induced to the leg members due, in part, to a lack of cross-section hoop stiffness. At least some known lattice-type support towers have vertical support legs that include a cross-section having an increased material mass and stiffness to facilitate reducing bending and torsional stresses and displacement.
In one aspect, a lattice tower for use with a wind turbine is provided. The lattice tower includes at least one support extending from a supporting surface. At least one cross-support member is coupled to the support to form the lattice tower. A reinforcement assembly is coupled to the support to transfer at least a portion of a bending load and a torsional load induced to the support to the reinforcement assembly to facilitate reducing a local distortion of the support.
In another aspect, a wind turbine is provided. The wind turbine includes a nacelle, a rotor rotatably coupled to the nacelle, and a lattice tower coupled to the nacelle for supporting the nacelle a distance from a supporting surface. The lattice tower includes at least one support extending from a supporting surface. At least one cross-support member is coupled to the support to form the lattice tower. A reinforcement assembly is coupled to the support to transfer at least a portion of a bending load and a torsional load induced to the support to the reinforcement assembly.
In yet another aspect, a method of designing a tower for a wind turbine is provided. The method includes acquiring, from a data collection system, a first element data representative of a plurality of members that form the tower. A first baseline performance data based at least in part on the acquired first element data is calculated by a structural design system. At least one first member with a calculated baseline performance data less than a predefined performance data is identified. A second element data representative of a reinforcement member selectively coupled to the first member to facilitate improving baseline performance data is identified.
The embodiments described herein facilitate assembling a wind turbine support tower. More specifically, the embodiments described herein include a reinforcement assembly that facilitates reducing bending and torsional stresses induced to support legs of the wind turbine tower from environmental loads, and facilitates reducing horizontal displacement of the wind turbine tower. Additionally, the reinforcement assembly described herein facilitates reducing a local distortion of the support legs. As used herein, the term “local distortion” refers to variations in a structural cross-sectional shape of a structural member due to bending stresses.
Rotor blades 22 are spaced about hub 20 to facilitate rotating rotor 18 to enable kinetic energy to be transferred from the wind into usable mechanical energy, and subsequently, electrical energy. In the exemplary embodiment, rotor blades 22 have a length ranging from about 30 meters (m) (99 feet (ft)) to about 120 m (394 ft). Alternatively, rotor blades 22 may have any suitable length that enables wind turbine 10 to function as described herein. For example, other non-limiting examples of rotor blade lengths include 10 m or less, 20 m, 37 m, or a length that is greater than 120 m. As wind strikes rotor blades 22 from a direction 28, rotor 18 is rotated about an axis of rotation 30. As rotor blades 22 are rotated and subjected to centrifugal forces, rotor blades 22 are also subjected to various forces and moments. As such, rotor blades 22 may deflect and/or rotate from a neutral, or non-deflected, position to a deflected position. Moreover, a pitch angle or blade pitch of rotor blades 22, i.e., an angle that determines a perspective of rotor blades 22 with respect to direction 28 of the wind, may be changed by a pitch adjustment system 32 to control the load and power generated by wind turbine 10 by adjusting an angular position of at least one rotor blade 22 relative to wind vectors.
In the exemplary embodiment, tower 12 is a lattice-type tower that includes two or more vertical support legs 40 and at least one cross-member 42 extending between vertical support legs 40 to form tower 12. Vertical support legs 40 extend between support surface 14 and nacelle 16 and define a vertical axis 43. Cross-member 42 is coupled to vertical support legs 40 at a cross-support region 44. In one embodiment, at least one cross-member 42 extends obliquely between a first vertical support leg 50 and a second vertical support leg 52. In the exemplary embodiment, tower 12 includes five vertical support legs 40. In an alternative embodiment, tower 12 includes more or less than five vertical support legs 40.
In the exemplary embodiment, at least one vertical support leg 40 includes a first or lower support member 54 and a second or upper support member 56. Lower support member 54 is coupled to a base 58 that is positioned at or near support surface 14. Lower support member 54 extends upward from base 58 towards upper support member 56. Upper support member 56 is coupled to and extends between lower support member 54 and nacelle 16 such that nacelle 16 is supported from tower 12 and is positioned a distance d1 above support surface 14.
In the exemplary embodiment, lower support member 54 extends obliquely from support surface 14 and is coupled to upper support member 56 at a transition region 60. Upper support member 56 extends substantially vertically from lower support member 54 towards nacelle 16.
Tower 12 further includes at least one reinforcement assembly 62 coupled to at least one vertical support leg 40 for facilitating reducing a bending loading and torsional loading induced to vertical support leg 40 from wind forces (represented by arrow 64) and to facilitate reducing a local distortion of vertical support leg 40. Reinforcement assembly 62 is further configured to facilitate reducing a horizontal displacement and/or rotational displacement of tower 12. In the exemplary embodiment, reinforcement assembly 62 is coupled to vertical support leg 40 at or near cross-support region 44 and/or transition region 60. Reinforcement assembly 62 is selectively positioned along a length of vertical support leg 40 between support surface 14 and nacelle 16. In one embodiment, reinforcement assembly 62 is coupled to vertical support leg 40 at any location along tower 12 to enable wind turbine 10 to operate as described herein. In an alternative embodiment, reinforcement assembly 62 is coupled to vertical support leg 40 along the full length of vertical support leg 62 extending from support surface 14 to nacelle 16.
During operation of wind turbine 10, wind acting on wind turbine 10 imparts wind forces 64 that are partly transformed into rotational energy and partly into a bending load (represented by arrow 66) tending to bend tower 12 in the direction of wind forces 64 and displace nacelle 16 a distance d2 from vertical axis 43. Bending load 66 tending to displace vertical support leg 40 in a horizontal direction and/or rotational direction is imparted to vertical support leg 40 from wind forces 64, such that bending and torsional stresses are induced to vertical support leg 40. Vertical support leg 40 transfers such bending and torsional stresses at least partly to reinforcement assembly 62, such that vertical support leg 40 is subjected to reduced bending and torsional loading during operation of wind turbine 10. Reinforcement assembly 62 is configured to facilitate increasing a stiffness strength in tower 12 to facilitate reducing a horizontal displacement and/or rotational displacement of tower 12 when subjected to wind forces 64.
In the exemplary embodiment, reinforcement assembly 100 includes a first reinforcement member 102 coupled to vertical support leg 40. First reinforcement member 102 includes a flange 104, a first flange extension 106, and an opposing second flange extension 108. Flange 104 is coupled to vertical support leg 40 such that an inner surface 110 of flange 104 extends between first arm 82 and second arm 84 and further defines cavity 88 between inner surface 110 and vertical support leg inner surface 86. First flange extension 106 extends outwardly from flange 104 substantially parallel to first wing wall 90. Second flange extension 108 extends outwardly from flange 104 substantially parallel with second wing wall 92. In the exemplary embodiment, at least one bolt 112 is inserted through a cooperating first opening 114 defined through first flange extension 106, first wing wall 90, and first cross-member 96 to fixedly couple first reinforcement member 102 to vertical support leg 40 and first cross-member 96. Similarly, at least one bolt 116 is inserted through a cooperating second opening 117 defined through second flange extension 108, second wing wall 92, and second cross-member 98 to fixedly couple first reinforcement member 102 to vertical support leg 40 and second cross-member 98. In an alternative embodiment, bolt 112 is inserted through cooperating first opening 114 defined through first flange extension 106 and first wing wall 90 to fixedly coupled first reinforcement member 102 to vertical support leg 40. Similarly, bolt 116 is inserted through cooperating second opening 117 defined through second flange extension 108 and second wing wall 92 to fixedly couple first reinforcement member 102 to vertical support leg 40. In a further alternative embodiment, first reinforcement member 102 is coupled to vertical support leg 40 using at least one of a weld, a fastener, a restraint clip, and any other suitable fastening member.
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User computer device 304 and structural design system 306 communicate with each other and/or network 302 using a wired network connection (e.g., Ethernet or an optical fiber), a wireless communication means, such as radio frequency (RF), an Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard (e.g., 802.11(g) or 802.11(n)), the Worldwide Interoperability for Microwave Access (WIMAX) standard, a cellular phone technology (e.g., the Global Standard for Mobile communication (GSM)), a satellite communication link, and/or any other suitable communication means. WIMAX is a registered trademark of WiMax Forum, of Beaverton, Oreg. IEEE is a registered trademark of Institute of Electrical and Electronics Engineers, Inc., of New York, N.Y.
Each of user computer device 304 and structural design system 306 includes a processor, as described herein with reference to
Processor 308 is operatively coupled to a communication interface 312 such that structural design system 306 is capable of communicating with a remote device, such as one or more user computer devices 304. Processor 308 may also be operatively coupled to data collection system 314. Data collection system 314 is any computer-operated hardware suitable for storing and/or retrieving data. In some embodiments, data collection system 314 is integrated in structural design system 306. For example, structural design system 306 may include one or more hard disk drives as data collection system 314. In other embodiments, data collection system 314 is external to structural design system 306 and may be accessed by a plurality of structural design systems 306. In one embodiment, data collection system 314 includes a database 316 for storing wind turbine data, including, without limitation, wind turbine tower attributes, wind turbine attributes, and/or wind turbine tower performance data.
In the exemplary embodiment, structural design system 306 is configured to store wind turbine element data in memory area 310 and/or data collection system 314. Wind turbine element data includes one or more element data that is representative of structural components of wind turbine 10, for example, such as tower 12, nacelle 16, and rotor 18. Wind turbine element data include wind turbine attributes, such as an identification attribute (e.g., a name), a dimensional attribute (e.g., a rotor disc area and/or a tower height), a component attribute (e.g., a set of included structural components), an environmental attribute (e.g. wind condition, such as wind direction and/or wind speed), a structural element attribute (e.g., weight of structural components, moment of inertia, width and length of component, modulus of elasticity of component, material properties of component), and/or a performance attribute (e.g. component loading, bending loading, bending stresses, torsional stresses, and/or and torsional loading).
In the exemplary embodiment, wind turbine element data includes shell elements representative of vertical support legs 40, cross-members 42, and/or reinforcement assembly 62. In an alternative embodiment, wind turbine element data includes three-dimensional data elements representative of vertical support legs 40, cross-members 42, and/or reinforcement assembly 62. In the exemplary embodiment, data collection system 314 is configured to receive wind turbine element data from user computing device 304.
User computer device 304 also includes at least one presentation device 324 for presenting information to user 326. Presentation device 324 is any component capable of conveying information to user 326. Presentation device 324 may include, without limitation, a display device (e.g., a liquid crystal display (LCD), organic light emitting diode (OLED) display, or “electronic ink” display) and/or an audio output device (e.g., a speaker or headphones). In some embodiments, presentation device 324 includes an output adapter, such as a video adapter and/or an audio adapter. An output adapter is operatively coupled to processor 320 and configured to be operatively coupled to an output device, such as a display device or an audio output device.
In some embodiments, user computer device 304 includes an input device 328 for receiving input from user 326. Input device 328 may include, for example, a keyboard, a pointing device, a mouse, a stylus, a touch sensitive panel (e.g., a touch pad or a touch screen), a gyroscope, an accelerometer, a position detector, and/or an audio input device. A single component, such as a touch screen, may function as both an output device of presentation device 324 and input device 328. User computer device 304 also includes a communication interface 330, which is configured to be coupled in communication with network 302 and/or structural design system 306.
Stored in memory area 322 are, for example, computer readable instructions for providing a user interface to user 326 via presentation device 324 and, optionally, receiving and processing input from input device 328. A user interface may include, among other possibilities, a web browser and/or a client application. Web browsers and client applications enable users, such as user 326, to display and interact with media and other information from a remote device, such as structural design system 306.
In the exemplary embodiment, data collection system 314 is configured to receive wind turbine element data from user computing device 304. Structural design system 306 is configured to acquire first wind turbine element data that is representative of a plurality of structural members of wind turbine 10 that includes tower 12 including vertical support leg 40 and/or cross-member 42, nacelle 16, rotor 18, and/or rotor blades 22. In the exemplary embodiment, structural design system 306 is configured to calculate a baseline performance data for each structural member. In one embodiment, structural design system 306 is configured to calculate the baseline performance data using finite element analysis. Structural design system 306 is further configured to calculate a deflection, a deformation, a bending stress, and/or a torsional stress of each structural member of tower 12. In one embodiment, baseline performance data is calculated using a maximum loading scenario that includes applying a maximum probable wind force 64 to tower 12 along direction 28. In an alternative embodiment, baseline performance data is calculated using a fatigue loading scenario that includes selectively applying a wind force to tower 12 over a predefined period of time. In another alternative embodiment, baseline performance data is calculated using a rotational loading scenario that includes selectively applying a wind force at a plurality of directions about an outer perimeter of tower 12.
In the exemplary embodiment, structural design system 306 is configured to compare the baseline performance of each structural member with a predefined baseline performance. Structural design system 306 is further configured to identify a structural member with a baseline performance that is less than the predefined performance. In one embodiment, structural design system 306 is configured to identity second wind turbine element data that is representative of a reinforcement assembly 62 that improves the baseline performance of the structural member when reinforcement assembly 62 is coupled to the structural member. Structural design system 306 is further configured to calculate a second baseline performance data based on the first element data and the second element data and verify the second baseline performance is equal to or greater than the predefined baseline performance. If the second baseline performance is less than the predefined baseline performance, structural design system 306 is configured to identify a third wind turbine element data that is representative of an alternative embodiment of reinforcement assembly 62, calculate a third baseline performance data based on the first element data and the third element data and verify the third baseline performance is equal to or greater than the predefined baseline performance.
An exemplary technical effect of the methods and system described herein includes at least one of: (a) acquiring, by a structural design system, a first element data representative of a plurality of members that represent a first tower; (b) calculating, by a structural design system, a first baseline performance data based at least in part on the acquired element data; (c) identifying at least one first member with a calculated baseline performance data that is less than a predefined performance data; (d) identifying a second element data representative of a first reinforcement assembly coupled to the identified member to facilitate improving baseline performance data.
The above-described systems and methods facilitate assembling a support tower that facilitates reducing a displacement of a wind turbine during operation. More specifically the support tower described herein includes a reinforcement assembly that is coupled to a tower support member to facilitate reducing stress induced to support tower members from wind loads. In addition, by providing a reinforcement assembly, a support tower may be assembled using support members that include a reduced cross-sectional thickness and material stiffness, thereby reducing the overall costs of manufacturing the support tower. As such, the cost of assembling a wind turbine is significantly reduced.
Exemplary embodiments of a support tower for use with a wind turbine and a system for designing the support tower are described above in detail. The systems and methods are not limited to the specific embodiments described herein, but rather, components of the systems and/or steps of the methods may be utilized independently and separately from other components and/or steps described herein. For example, the methods may also be used in combination with wind turbine support systems, and are not limited to practice with only the support towers as described herein. Rather, the exemplary embodiment can be implemented and utilized in connection with many other wind turbine support systems.
Although specific features of various embodiments of the invention may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the invention, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.
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 language of the claims.