Patent Application
20170058869
The present invention relates generally to the field of wind turbines, and more particularly to a conduit assembly for securing a lightning protection cable within a rotor blade of a wind turbine using thermoplastic welding.
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, a generator, a gearbox, a nacelle, and one or more rotor blades. The rotor blades capture kinetic energy from wind using known foil principles and transmit the kinetic energy through rotational energy 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 that may be deployed to a utility grid.
The rotor blades typically consist of a suction side shell and a pressure side shell that define an internal cavity when arranged together. Typically, an internal shear web extends between the pressure and suction side shell members and is bonded to opposing spar caps affixed to the inner surfaces of the shell members. In addition, wind turbines typically include a lightning protection system having one or more lightning receptors disposed on the exterior of the pressure and/or suction side shells of the rotor blade and a lightning protection cable electrically coupling the lightning receptor(s) to ground. Thus, the lightning protection cable typically extends through the internal cavity of the rotor blade from the blade tip to the blade root and down through the tower to a ground location. Accordingly, when lightning strikes the rotor blade, the electrical current may flow through the lightning receptor(s) and may be conducted through the lightning protection cable to the ground.
The lightning protection cable is typically attached directly within the rotor blade (e.g. to the shear web and/or to an internal surface of the body shell) using fiberglass laminates and bond paste. Thus, stresses and strains experienced by the rotor blade pass directly to the lightning protection cable. Such stresses and strains can cause damage and/or breakage to the lightning protection cable, thereby requiring immediate repair to ensure the lightning protection system remains operable. In addition, the process of attaching the lightning protection cable to the blade shell can be tedious and time-consuming.
Accordingly, there is a need for improved and effective systems and methods for securing the lightning protection cable of the lighting protection system to the rotor blade of the wind turbine.
Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
In one aspect, the present disclosure is directed to a conduit assembly for securing a lightning protection cable of a wind turbine lightning protection system within an internal cavity of a wind turbine rotor blade. The conduit assembly includes one or more conduit members arranged together to define an open passageway configured to receive at least a portion of the lightning protection cable along a length thereof. Further, the conduit member(s) include one or more weldable surfaces. Thus, the weldable surface(s) are configured for securement to at least one of a blade segment, opposing spar caps, a shear web of the rotor blade, or any other suitable blade component. More specifically, the one or more weldable surfaces are constructed, at least in part, of a thermoplastic material such that the conduit members can be easily welded to one or more of the blade components, e.g. also constructed at least in part of a thermoplastic material, as described herein.
For example, in one embodiment, the blade segment, the opposing spar caps, and/or the shear web of the rotor blade may be constructed, at least in part, of a thermoplastic material. In another embodiment, the weldable surface(s) may include one or more flanges. Thus, in certain embodiments, the weldable surface(s) of the conduit member(s) may be welded to the shear web. Alternatively, the weldable surfaces of the conduit member(s) may be welded to one or more blade segments. In still another embodiment, the weldable surface(s) of the conduit member(s) may be welded to the shear web and the one or more blade segments. In yet another embodiment, the weldable surfaces of the conduit member(s) may be welded to one or more of the opposing spar caps.
In additional embodiments, one or more of the conduit members may be reinforced with one or more fiber materials, including but not limited to glass fibers, carbon fibers, metal fibers, polymer fibers, ceramic fibers, nanofibers, or similar, or any combinations thereof.
In further embodiments, the conduit member(s) may be formed via at least one of pultrusion, vacuum infusion, resin transfer molding (RTM), light resin transfer molding (RTM), vacuum assisted resin transfer molding (VARTM), a belt-pressing process, a forming process, injection molding, extrusion, vacuum forming, thermoforming, blow molding, or any other suitable manufacturing process.
In yet another embodiment, the conduit member(s) may include any suitable cross-sectional shape so as to accommodate the lightning protection cable therein. For example, in certain embodiments, the cross-sectional shape may include at least one of the following cross-sectional profiles: omega-shaped, square, elliptical, U-shaped, C-shaped, L-shaped, triangular, rectangular, round, arcuate, or similar.
In another aspect, the present disclosure is directed to a rotor blade assembly for a wind turbine. The rotor blade assembly includes a blade root, a blade tip, and at least one blade segment arranged between the blade root and the blade tip. Further, the blade segment includes a pressure side and a suction side arranged together to define an internal cavity. The rotor blade assembly also includes opposing spar caps configured on opposing internal surfaces of the pressure and suction sides and at least one shear web configured between the opposing spar caps. In addition, at least one of the blade segment, one or more of the spar caps, and/or the shear web may be constructed, at least in part, of a thermoplastic material. The rotor blade assembly further includes a lightning protection cable configured at least partially within the internal cavity. The lightning protection cable is configured to electrically couple a plurality of lightning receptors so as to form a conductive circuit. Further, the rotor blade assembly includes a conduit assembly configured to receive at least a portion of the lightning protection cable along a length thereof. The conduit assembly is constructed, at least in part, of a thermoplastic material. As such, the conduit assembly may be welded to the blade segment, one or more of the spar caps, the shear web, and/or any other suitable blade component within the internal cavity. It should be understood that the conduit assembly may be further configured according to any of the embodiments as described herein.
In yet another aspect, the present disclosure is directed to a method for securing a lightning protection cable within an internal cavity of a rotor blade of wind turbine. The method includes placing the lightning protection cable at least partially within a passageway of a conduit assembly. The conduit assembly may be constructed, at least in part, of a thermoplastic material. Thus, the method also includes welding the conduit assembly within the internal cavity of the rotor blade to at least one of an inner surface of a blade segment, one or more spar caps, and/or a shear web of the rotor blade so as to secure the lightning protection cable therein. Further, the blade segment(s), the one or more spar caps, and/or the shear web may be constructed, at least in part, of a thermoplastic material. Accordingly, the thermoplastic conduit assembly can be easily welded to one or more of the various internal blade components of the rotor blade. In addition, it should be understood that the method steps as described herein may be performed in any suitable order and are not limited to the order described herein. For example, in one embodiment, the method may include welding the conduit assembly within the internal cavity of the rotor blade and then placing the lightning protection cable at least partially within a passageway of the conduit assembly.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art is set forth in the specification, which makes reference to the appended figures, in which:
Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention include such modifications and variations as come within the scope of the appended claims and their equivalents.
Generally, the present disclosure is directed to improved assemblies and method for securing a lightning protection cable within a rotor blade of a wind turbine. More specifically, the rotor blade may include one or more blade segments arranged together to form the outer blade shell of the rotor blade and one or more structural components, e.g. opposing spar caps having at least one shear web arranged therebetween, configured within an internal cavity of the rotor blade. In addition, in certain embodiments, the blade segments, the spar caps, and/or the shear web may be constructed, at least in part, of a thermoplastic material. Further, the wind turbine may include a lightning protection system having a lightning protection cable that electrically couples a plurality of lightning receptors configured with the rotor blade so as to form a conductive circuit. Thus, the rotor blade also includes a thermoplastic conduit assembly that is configured to receive at least a portion of the lightning protection cable along a length thereof. Accordingly, due to the similar materials, the conduit assembly can be easily secured within the internal cavity of the rotor blade (e.g. to the shear web and/or the inner surface of the blade segments) via welding so as to maintain a location of the lightning protection cable.
Accordingly, the present disclosure provides many advantages not present in the prior art. For example, the thermoplastic conduit assembly can be quickly and easily installed within the internal cavity of the rotor blade via welding, thereby improving cycle time, costs, and complexity. Further, the present disclosure is configured to reduce deflection and/or strain transfer between the rotor blade and the lightning protection cable since the lightning protection cable is not directly secured to the rotor blade. Thus, the stresses and strains experienced by the rotor blade will not pass to the lightning protection cable. Accordingly, the life of the cable is increased under fatigue loading. In addition, the conduit assembly allows the lightning protection cable to be placed with better precision than prior art methods that included infusing the cable to the shear web.
Referring to the drawings,
Referring now to
In several embodiments, the body shell 21 of the rotor blade 16 may be formed as a single, unitary component. Alternatively, the body shell 21 may be formed from a plurality of shell components. For example, the body shell 21 may be manufactured from a first shell half generally defining the pressure side 34 of the rotor blade 16 and a second shell half generally defining the suction side 36 of the rotor blade 16, with such shell halves being secured to one another at the leading and trailing edges 26, 28 of the blade 16. In addition, as shown in
It should be understood that the body shell 21 may generally be formed using any suitable material, including but not limited to a thermoset material, a thermoplastic material, one or more fiber materials, and/or combinations thereof. For instance, in one embodiment, the body shell 21 may be formed entirely from a laminate composite material, such as a carbon fiber reinforced laminate composite or a glass fiber reinforced laminate composite. Alternatively, one or more portions of the body shell 21 may be configured as a layered construction and may include a core material, formed from a lightweight material such as wood (e.g., balsa), foam (e.g., extruded polystyrene foam) or a combination of such materials, disposed between layers of laminate composite material. In alternative embodiments, the body shell 21 may be formed, at least in part, from a fiber-reinforced thermoplastic material.
Referring particularly to
It should also be understood that the spar caps 20, 22 and/or the shear web(s) 24 may generally be formed from any suitable material, including but not limited to a thermoset material, a thermoplastic material, and/or combinations thereof. For instance, in one embodiment, the spar caps 20, 22 and/or the shear web(s) 24 may be formed entirely from a laminate composite material, such as a carbon fiber reinforced laminate composite or a glass fiber reinforced laminate composite. Alternatively, the spar caps 20, 22 and/or the shear web(s) 24 may be formed, at least in part, from a thermoplastic material.
The thermoplastic materials as described herein generally encompass a plastic material or polymer that is reversible in nature. For example, thermoplastic materials typically become pliable or moldable when heated to a certain temperature and returns to a more rigid state upon cooling. Further, thermoplastic materials may include amorphous thermoplastic materials and/or semi-crystalline thermoplastic materials. For example, some amorphous thermoplastic materials may generally include, but are not limited to, styrenes, vinyls, cellulosics, polyesters, acrylics, polysulphones, and/or imides. More specifically, exemplary amorphous thermoplastic materials may include polystyrene, acrylonitrile butadiene styrene (ABS), polymethyl methacrylate (PMMA), glycolised polyethylene terephthalate (PET-G), polycarbonate, polyvinyl acetate, amorphous polyamide, polyvinyl chlorides (PVC), polyvinylidene chloride, polyurethane, or any other suitable amorphous thermoplastic material. In addition, exemplary semi-crystalline thermoplastic materials may generally include, but are not limited to polyolefins, polyamides, fluropolymer, ethyl-methyl acrylate, polyesters, polycarbonates, and/or acetals. More specifically, exemplary semi-crystalline thermoplastic materials may include polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polypropylene, polyphenyl sulfide, polyethylene, polyamide (nylon), polyetherketone, or any other suitable semi-crystalline thermoplastic material. Further, the thermoset materials as described herein generally encompass a plastic material or polymer that is non-reversible in nature. For example, thermoset materials, once cured, cannot be easily remolded or returned to a liquid state. As such, after initial forming, thermoset materials are generally resistant to heat, corrosion, and/or creep. Example thermoset materials may generally include, but are not limited to, some polyesters, some polyurethanes, esters, epoxies, or any other suitable thermoset material.
Referring now to
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Still referring to
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In addition, the conduit assembly 54 is constructed, at least in part, of a thermoplastic material. Thus, at least a portion of the thermoplastic conduit assembly 54 can be easily welded to the shear web 24, the spar caps 20, 22, the blade segments 29, and/or any other suitable rotor blade component, which will be described in more detail below.
More specifically, as shown in
As shown generally in the figures, the conduit members 55 may include any suitable cross-sectional profile so as to receive the lightning protection cable 41 therein, including, but not limited to any of the following cross-sectional profiles: omega-shaped, square, elliptical, U-shaped, C-shaped, L-shaped, triangular, rectangular, round, or similar or any combinations thereof. For example, as shown in
In addition, as shown in
It should be understood that the conduit member(s) 55 may be formed using any suitable means. For example, in certain embodiments, the conduit member(s) 55 of the conduit assembly may be formed via at least one of pultrusion, vacuum infusion, resin transfer molding (RTM), light resin transfer molding (RTM), vacuum assisted resin transfer molding (VARTM), a belt-pressing process, a forming process, injection molding, extrusion, vacuum forming, thermoforming, blow molding, or any other suitable manufacturing process. As used herein, the terms “pultrusion” generally encompasses processes that utilize reinforced materials (e.g. fibers or woven or braided strands) that are impregnated with a resin and pulled through a stationary die such that the resin cures or undergoes polymerization. As such, the pultrusion process is typically characterized by a continuous process of composite materials that produces composite parts having a constant cross-section. Thus, the conduit member(s) 55 may include pultrusions constructed of reinforced thermoplastic materials. Further, the conduit member(s) 55 may be formed of the same pre-cured composites or different pre-cured composites. In addition, the conduit member(s) 55 may be reinforced with one or more fiber materials, including but not limited to glass fibers, carbon fibers, metal fibers, polymer fibers, ceramic fibers, nanofibers, or similar, or any combinations thereof.
Referring generally to
For example, as shown in
Referring now to
In addition, it should be understood that the method steps as described herein may be performed in any suitable order and are not limited to the order described herein. For example, in an alternative embodiment, the method may include welding the conduit assembly 54 within the internal cavity 38 of the rotor blade 16 and then placing the lightning protection cable 41 at least partially within a passageway 56 of the conduit assembly 54.
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 include 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.
