Pre-staged wind turbine rotor blades for retrofitting with replacement blade tip segments

Abstract

A method for manufacturing a wind turbine blade (28) pre-staged for subsequent retrofitting with a replacement blade tip segment (30) comprises providing the wind turbine blade with a continuous spar structure (42) from a root end (19) to a tip end (17) of the wind turbine blade. At predetermined spanwise locations, one of the spanwise extending spar structure (40) or the spanwise extending receiver section (54) is configured with the spar structure (42).

Description

Technical Field

[0001] The present subject matter relates generally to wind turbine rotor blades, and more particularly to a method for field retrofitting an existing blade tip segment with a replacement blade tip segment. Background Art

[0002] Wind power is considered to be one of the cleanest and most environmentally friendly energy sources currently available, and wind turbines have attracted increasing attention in this regard. Modern wind turbines typically include a tower, a generator, a gearbox, a nacelle, and one or more rotor blades. The rotor blades obtain kinetic energy from the wind using the known airfoil principle, and the kinetic energy is transferred through rotational energy to rotate a shaft, which connects the rotor blades to a gearbox, or directly to a generator if a gearbox is not used. The generator then converts the mechanical energy into electrical energy that can be deployed to the utility grid.

[0003] Wind turbine rotor blades generally include a body shell formed from two shell halves of composite laminate material. The shell halves are generally manufactured using a molding process and then coupled together along corresponding ends of the rotor blade. Generally, the body shell is relatively lightweight and has structural properties (e.g., stiffness, bending resistance, and strength) that are not configured to withstand bending moments and other loads imposed on the rotor blade during operation.

[0004] In some cases, it may be desirable to modify a rotor blade on an operating, field wind turbine. For example, it may be desirable to change the physical characteristics of the blade for noise reduction benefits, or to change the power characteristics of the blade. Such a modification may require replacing an existing blade tip with a different blade tip segment. However, modification of an existing blade tip is a difficult and challenging process, particularly if the process is performed in the field (at the location of the wind turbine). In addition, the joint between the replacement blade tip segment and the existing blade root segment typically dictates the maximum load limit of the blade. Therefore, modified blade tip segments have been limited to relatively short lengths.

[0005] As the size of wind turbine rotor blades has increased significantly in recent years, difficulties have arisen in integrated manufacturing and the delivery and transportation of blades to location. In response, the industry is developing segmented wind turbine rotor blades, in which individual blade segments are manufactured and transported to the site to be assembled into complete blades ("connected" blades). In some configurations, the blade segments are connected together by a beam structure that extends from one blade segment to another blade segment in the span direction. For example, reference is made to U.S. Patent Publication No. 2015 / 0369211, which describes a first blade segment having a beam structure extending longitudinally that is structurally connected to a second blade segment at a receiver segment. The beam structure forms part of an internal spar structure for the blade and includes a shear web connected to a suction side spar cap and a pressure side spar cap. A plurality of bolted joints are provided on the beam structure for connection to a receiver segment in the second blade segment, and a plurality of bolted joints are located at chord-wise joints between the blade segments.

[0006] Similarly, U.S. Patent Publication No. 2011 / 0091326 describes a connected blade in which a first blade portion and a second blade portion extend from a joint in opposite directions. Each blade portion includes a spar section forming a structural member of the blade and extending longitudinally, wherein the first blade portion and the second blade portion are structurally connected by a spar bridge connecting the spar sections.

[0007] With conventional blade structures and retrofit processes, extensive and time-consuming processes are involved in modifying an existing blade to accommodate a replacement blade tip. The industry would benefit from a wind turbine rotor blade that is "pre-staged" for subsequent retrofit with a replacement blade tip, wherein such pre-staging involves the construction of a spar structure within the blade that may not be necessary with an existing spar structure and is specifically provided to reduce the steps, time, and complexity of retrofitting for a replacement blade tip. Summary of the invention

[0008] Aspects and advantages of the invention will be set forth in the following description, or may be obvious from the description, or may be learned through practice of the invention.

[0009] In one aspect, the present invention includes a method for manufacturing a wind turbine blade that is pre-staged for subsequent retrofitting with a replacement blade tip segment. An embodiment of the method includes providing a wind turbine blade with a continuous spar structure from a root segment to a tip segment of the blade. The spar structure may include, for example, opposing shear webs and opposing spar caps that define a box-beam spar structure. At a predefined spanwise position, a spanwise extending beam structure or one of the spanwise extending receiver segments is joined to the spar structure by securing the root end of the receiver segment or spar structure to the spar structure. The tip end of the receiver segment or beam structure is disengaged (not secured to) the spar structure. The beam structure has dimensions for insertion into a mating receiver segment in a replacement blade tip segment at a subsequent time. Likewise, the receiver segment is sized to receive a mating beam structure extending from a replacement blade tip segment. In embodiments where the spar structure includes opposing shear webs, the root end of the receiver segment or beam structure may be secured between the shear webs, for example, using an adhesive.

[0010] The method may further include, after manufacturing the wind turbine blade, retrofitting the wind turbine blade with a replacement blade tip segment by cutting the existing blade tip segment from the wind turbine blade at the chord-wise joint line, such that the tip end of the beam structure extends from the remaining blade root segment in the span direction beyond the chord-wise joint line, or the receiver segment is exposed at the chord-wise joint line. The spar structure in the blade root segment extending along the tip end of the receiver segment or the beam structure may also be removed, such that only the beam structure extends from the blade root segment, or the receiver segment is exposed at the chord-wise joint line. The replacement blade tip segment is then aligned and connected with the blade root segment in the span direction, such that the beam structure moves into the receiver segment of the replacement blade tip segment, or the beam structure extending from the replacement blade tip segment slides into the receiver segment. The blade shell components of the blade root segment and the replacement blade tip segment may then be provided with a finishing surface at the joint line.

[0011] As discussed above, the spar structure may include opposing shear webs, wherein the root end of the receiver section or the spar structure is between and secured to the shear webs, and wherein the process of removing the spar structure includes cutting away the shear web along the tip end of the spar structure or the tip end of the receiver section.

[0012] The wind turbine blade is operable on a wind turbine at a field location, wherein the method comprises removing and lowering the wind turbine blade from a rotor hub of the wind turbine, and performing the retrofitting procedure with the wind turbine blade in a down-tower position relative to the rotor hub.

[0013] The method may further include creating and maintaining an inventory of replacement blade tip segments, wherein for the retrofit process, one of the replacement blade tip segments is selected from the inventory and transported to the on-site location.

[0014] The present invention also includes various embodiments of a wind turbine blade that is pre-staged for subsequent retrofitting with a replacement blade tip segment, wherein the blade includes a pressure side shell and a suction side shell, the suction side shell being connected to the pressure side shell along a leading edge and a trailing edge so that an internal cavity is defined between the pressure side shell and the suction side shell. A continuous spar structure is constructed within the internal cavity from the root end to the tip end of the wind turbine blade. At a predefined spanwise position, a spanwise extending beam structure or one of the spanwise extending receiver sections is constructed with a spar structure. The spanwise extending beam structure is configured for insertion into a mating receiver section in a replacement blade tip segment, or the receiver section is configured for receiving a mating beam structure extending from a replacement blade tip segment.

[0015] In a particular embodiment of the wind turbine blade, the beam structure comprises a root end fixed to the spar structure and a tip end adjacent to the spar structure and not fixed to the spar structure, wherein when the wind turbine blade is retrofitted with a replacement blade tip segment, the spar structure can be removed from the tip end of the spar structure. Alternatively, the segment comprises a root end fixed to the spar structure such that the receiver segment extends at least to the position of the chord-wise joint line, at which position the replacement blade tip segment is to be retrofitted.

[0016] The spar structure may comprise opposed shear webs, wherein a root end of the spar structure or a root end of a spanwise extending receiver section is configured between the shear webs.

[0017] 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 present invention and together with the description serve to explain the principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] A full and open disclosure of the invention, including its best mode for one of ordinary skill in the art, is set forth in the specification with reference to the accompanying drawings, in which:

[0019] Figure 1 A perspective view showing one embodiment of a wind turbine that may utilize retrofitted blades according to the present disclosure;

[0020] Figure 2 is a view of a pre-staged wind turbine blade cap that has been retrofitted with a replacement blade tip segment;

[0021] Figure 3 are views of various embodiments of pre-staged wind turbine blade caps that have been retrofitted with replacement blade tip segments;

[0022] Figures 4a to 4c is a sequential conceptual view of an embodiment for subsequent retrofitting of a pre-staged wind turbine blade according to aspects of the present disclosure;

[0023] Figure 5a to Figure 5c is a sequential conceptual view of an alternative embodiment for subsequent retrofitting of a pre-staged wind turbine blade according to aspects of the present disclosure; and

[0024] Figures 6a to 6e is a sequential conceptual view of an embodiment of a refitting process according to aspects of the present disclosure. DETAILED DESCRIPTION

[0025] Reference will now be made in detail to embodiments of the present invention, one or more examples of which are shown in the accompanying drawings. Each example is provided by way of explanation of the present invention without limiting the present invention. In fact, it will be clear to those skilled in the art that various modifications and variations may be made in the present invention without departing from the scope or spirit of the present invention. For example, a feature shown or described as a part of an embodiment may be used in conjunction with another embodiment to produce a further embodiment. Therefore, it is expected that the present invention covers such modifications and variations as fall within the scope of the appended claims and their equivalents.

[0026] Generally, the present subject matter relates to methods for manufacturing wind turbine rotor blades (and resulting blades) that are pre-staged for subsequent retrofitting with replacement blade tip segments.

[0027] Now referring to the accompanying drawings, Figure 1 1 is a side view of an exemplary wind turbine 10 having a plurality of rotor blades 28 that may be retrofitted according to aspects of the present disclosure. The wind turbine 10 shown is a horizontal axis wind turbine. Alternatively, the wind turbine 10 may be a vertical axis wind turbine. The wind turbine 10 includes a tower 12 extending from a support surface 14, a nacelle 16 mounted on the tower 12, a generator 18 located within the nacelle 16, a gearbox 20 coupled to the generator 18, and a rotor 22 rotationally coupled to the gearbox 20 using a rotor shaft 24. The rotor 22 includes a rotatable hub 26, wherein rotor blades 28 are coupled to the rotatable hub 26 and extend outwardly from the rotatable hub. Each rotor blade 28 includes a blade tip 17 and a blade root 19, as well as corresponding root end blade segments 32 and tip end blade segments 29.

[0028] Figure 2 is a view of a modified wind turbine blade 70, which is formed by modifying Figure 4a-4cThe pre-staged blade 28 is made such that the root end blade segment 32 of the pre-staged rotor blade 28 is retrofitted with a replacement blade tip segment 30, the replacement blade tip segment extending from a chord-wise joint 34 in opposite span-wise directions. Each blade segment 30, 32 includes a pressure side shell member 31 and a suction side shell member 33. As described in more detail below, the blade segments 30, 32 are connected by an internal joint structure 36 extending into the two blade segments 30, 32 to facilitate the joining of the blade segments 30, 32. The blade 70 includes a leading edge 74 and a trailing edge 76, as well as a root portion 19 and a tip portion 17, wherein the upper and lower shell members 31, 33 are joined together at the leading edge 74 and the trailing edge 76. The pre-staged blade 28 and the retrofitted blade 70 include an internal cavity in which various structural components, such as a spar cap 46 and a shear web 44, are constructed. The construction and function of the internal structural components of blade 70 are well known to those skilled in the art and need not be described in detail herein in order to understand and appreciate the present invention.

[0029] Still reference Figure 2 and Figure 4a-4c As with any number of conventional wind turbine blade designs, the pre-staged wind turbine blade 28 is provided with a continuous spar structure 42 from the root section 19 to the tip section 17. The spar structure 42 may include, for example, opposing shear webs 44 and opposing spar caps 46 that define a box-beam spar structure 42. The span-wise extending beam structure 40 is joined to the spar structure 42 during manufacture of the pre-staged blade 28 by securing the root end 41 of the beam structure 40 to the spar structure 42 and attaching substantially the entire tip end 43 of the beam structure 40 to the spar structure 42 at a pre-defined span-wise position. Figure 2 As will be appreciated, the beam structure 40 is sized for insertion into the mating receiver section 54 within the replacement blade tip segment 30 during the retrofit process.

[0030] exist Figure 4a-4c In an embodiment in which the spar structure 42 includes opposing shear webs 44, the root end 41 of the spar structure 40 may be fixed between the shear webs 44, for example, by adhesive, mechanical means or any other suitable means. Figure 4b and Figure 4c , the tip 43 of the beam structure 40 may be adjacent to the shear web 44, but not attached to the shear web 44, so that the shear web 44 may be easily cut away from the tip 43 for subsequent retrofitting with a replacement blade tip segment 30. To this end, as discussed above, the shell members 31, 33 of the blade tip segment 29 (pre-staged blade 28) are cut away at the chord-wise joint line 34, so that the tip 43 of the beam structure extends beyond the chord-wise joint line 34 from the remaining blade root segment 32 in the span direction. Figure 4cAs shown in FIG. 1 , the spar structure 42 in the blade root segment 32 extending along the tip end 43 of the beam structure 40 can be removed at the same time or after the blade shell components 31 , 33 are cut away, so that only the beam structure 40 extends from the blade root segment 32. Then, the replacement blade tip segment 30 can be aligned and connected with the blade root segment 32 during the refitting process, wherein the tip end 43 of the beam structure 40 is slid into the mating receiver section 54 of the replacement blade tip segment 30, as shown in FIG. Figure 2 As seen in.

[0031] Figure 3 and Figure 5a-5c The embodiment of the present invention provides a pre-staged wind turbine blade 28 with a pre-staged receiver section 54 having a root end 55 fixed to the spar structure 42. The opposite end of the receiver section 54 extends at least to the chord-wise joint line 34 and can be fixed to the web 44 along the entire length of the receiver section 54. Figure 5b and Figure 5c As shown in FIG. 1 , when the tip segment 29 is cut from the pre-staged blade 28, the spar structure including the web 44 (and / or) is subsequently cut back to the joint line 34. If the receiver section 54 extends beyond the joint line 34 (such as Figure 5b As shown in FIG. 3 ), the length of the receiving section 54 can also be trimmed to the joint line 34 so that the open end of the receiving section 54 is at the joint line ( Figure 5c ) is exposed for receiving a beam structure 40 extending from a replacement blade tip segment 30.

[0032] Figures 6a to 6e An embodiment of the present method for retrofitting a pre-staged wind turbine rotor blade 28 in the field is depicted sequentially, wherein the blade 28 is still attached to the rotor hub in an up-tower position. Alternatively, the pre-staged wind turbine blade 28 may be removed and lowered from the hub 26 using any suitable process, and the retrofitting process may be performed with the wind turbine blade 28 in a down-tower position relative to the rotor hub 26.

[0033] Figure 6a A pre-staged rotor blade 28 is depicted on the rotor hub 26 at the six o'clock position, the blade 28 comprising a root blade segment 32 and an integral blade tip segment 29 .

[0034] Figure 6b A chord-wise cut is depicted in the blade 28 at a location defining a chord-wise joint line 34. In this embodiment, the cut may be made completely through the blade 28, wherein the existing blade tip segment 29 is removed, such as Figure 6c The remaining spar structure 42 is drawn in the blade root segment 32 ( Figure 6cIn an alternative embodiment where the pre-staged blade 28 includes a pre-staged spar structure 40, the cut at the chord-wise joint line 34 will be made through the blade shell members 31, 33, leaving the spar structure 42 (e.g., web 44 and spar cap 46) substantially intact (as described above with respect to Figure 5b as drawn and discussed).

[0035] Figure 6c The blade root segment 32 is depicted, wherein the receiver section 54 is exposed at the joint line 34 .

[0036] Figure 6d The drawing depicts the selection of one of the pre-formed replacement blade tip segments 30 from the inventory 60 and the spanwise connection of the segment 30 to the blade root segment 32. Specifically, as the replacement blade tip segment 30 is moved in the spanwise direction, the beam structure 40 slides into a pre-staged receiver segment 54 within the blade root segment 32. To secure the beam structure 40 to the receiver segment 54, an end pin 52 on the root end 43 of the beam structure 40 extends through a slot ( Figure 3 ), and the chord-wise oriented slots in the receiver section 54 are aligned with corresponding slots in the beam structure 40. Figure 3 As particularly seen in FIG. 1 , the chordal pin 53 is then inserted through the aligned slots.

[0037] Figure 6e A replacement blade tip segment 30 and a blade shell member secured to a blade root segment 32 are depicted, the blade shell member being provided with a finish at a joint line 34, such as a fiberglass, epoxy, or other repair type finish that provides a relatively smooth and aerodynamic surface at the joint line 34 between the replacement blade tip segment 30 and the shell member of the root end blade segment 32. The finish may include a sealing tape 68 wrapped around the blade shell members 31, 33 at the joint line 34. Thus, Figure 6e The leaves in the Figure 3 The complete modified blade 70 is depicted in FIG.

[0038] 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 that are insubstantially different from the literal language of the claims.

Claims

1. A method for manufacturing and retrofitting a wind turbine blade (28) pre-staged for subsequent retrofitting with a replacement blade tip segment (30), the method comprising: Providing the wind turbine blade (28) with a continuous and non-segmental spar structure (42) from a root end (19) to a tip end (17) of the wind turbine blade; as well as A spanwise extending beam structure (40) is joined to the continuous and non-segmented spar structure at a predefined spanwise position; wherein the beam structure (40) is joined to the spar structure (42) by securing the root end (41) of the beam structure to the spar structure by adhesive or mechanical means and disengaging the tip end (43) of the beam structure from the spar structure, the beam structure being sized for insertion into a mating receiver section (54) within the replacement blade tip segment.

2. The method according to claim 1, characterized in that The spar structure (42) includes opposing shear webs (44), and further includes fixing the root end (41) of the beam structure (40) between the shear webs.

3. The method according to claim 1 or claim 2, characterized in that: The method further comprises retrofitting the wind turbine blade (28) at a time after manufacturing the wind turbine blade by: cutting an existing blade tip segment (29) from the wind turbine blade at a chord-wise joint line (34) such that a tip end (43) of the beam structure (40) extends spanwise from a remaining blade root segment (32) beyond the chord-wise joint line; removing the spar structure (42) from a tip end of the spar structure; aligning and connecting the replacement blade tip segment (30) with the blade root segment in the spanwise direction such that the beam structure moves into a mating receiver section of the replacement blade tip segment; as well as The blade shell components (31, 33) of the blade root segment and the replacement blade tip segment are provided with a finished surface at the joint line.

4. The method according to claim 3, characterized in that The spar structure (42) includes opposing shear webs (44), and the root end (41) of the beam structure (40) is between and secured to the shear webs, and wherein removal of the spar structure includes cutting away the shear webs along the tip end (43) of the beam structure (40).

5. The method according to claim 3, characterized in that: The wind turbine blade (28) is operating on a wind turbine (10) at a field location, the method comprising performing a retrofit procedure with the wind turbine blade in an on-tower position on a rotor hub (26) of the wind turbine.

6. The method according to claim 3, characterized in that The wind turbine blade (28) is operated on a wind turbine (10) at a field location, the method comprising removing and lowering the wind turbine blade from a rotor hub (26) of the wind turbine and performing a refitting procedure with the wind turbine blade in a down-tower position relative to the rotor hub.

7. The method according to claim 3, characterized in that The method further includes creating and maintaining an inventory (60) of the replacement blade tip segments (30), wherein for the retrofit process, one of the replacement blade tip segments is selected from the inventory and transported to an on-site location.

8. A wind turbine blade (28) pre-staged for subsequent retrofitting with a replacement blade tip segment (30), comprising: A pressure side shell (31); a suction side shell (33) joined to the pressure side shell along a leading edge (74) and a trailing edge (76) such that an interior cavity is defined between the pressure side shell and the suction side shell; a continuous and non-segmental spar structure (42) within the internal cavity from the root end (19) to the tip end (17) of the wind turbine blade; as well as A span-wise extending beam structure (40) is configured with the continuous and non-segmental spar structure at a predefined span-wise position; wherein the span-wise extending beam structure (40) is configured for insertion into a mating receiver section (54) in a replacement blade tip segment (30); The beam structure (40) comprises a root end (41) fixed to the spar structure (42) by adhesive or mechanical means and a tip end (43) adjacent to the spar structure and not fixed to the spar structure, wherein the spar structure can be removed from the tip end of the beam structure when the wind turbine blade is retrofitted with the replacement blade tip segment (30).

9. The wind turbine blade (28) according to claim 8, characterized in that The spar structure (42) includes opposed shear webs (44) including a root end (41) of the spar structure (40) fixedly constructed between the shear webs.

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