HYBRID POLTRUSION PLATES FOR A CONDUCTIVE SPAR CAP OF A WIND TURBINE BLADE

Abstract

The present invention relates to a method of manufacturing a wind turbine blade shell component (38), the method comprising the steps of providing a plurality of abraded pultrusion plates (64) having abraded edges, arranging the abraded pultrusion plates (64) in layers on blade shell material (89) in a mould (77) for the blade shell component, the layers being separated by electrically conductive interlayers, and bonding the abraded pultrusion plates (64) with the blade shell material to form the blade shell component, wherein each pultrusion plate (64) is formed of a pultrusion fibre material comprising glass fibres and carbon fibres. The invention also relates to a reinforcing structure for a wind turbine blade, the reinforcing structure comprising a plurality of pultrusion plates according to the present invention.

Claims

1-34. (canceled)

35. A lightning protection system (102) for a wind turbine blade, the lightning protection system comprising a lightning conductor (104) disposed at least partially in the interior of the blade, one or more electrically conductive lightning receptors (106, 107, 108) disposed on one or more of the surfaces of the blade, wherein the one or more electrically conductive lightning receptors are electrically connected to a spar cap, wherein the spar cap comprises a plurality of abraded pultrusion plates (64) which have been obtained by abrading each of a first plurality of pultrusion plates, wherein each pultrusion plate (64) of the first plurality of pultrusion plates comprises a top surface (81), an opposing bottom surface (82), a first lateral surface (83) and an opposing second lateral surface (84), wherein the pultrusion plate is formed of a plurality of tows of carbon fibre material (68), and wherein adjoining tows of carbon fibre material are provided along the entire lateral surfaces (83, 84) of the pultrusion plate, and wherein the abrading of each of the first plurality of pultrusion plates to obtain the plurality of abraded pultrusion plates includes removing at least a part of each of the edges at which the top surface (81) meets the lateral surfaces (83, 84) and the edges at which the bottom surface (82) meets the lateral surfaces (83, 84), and wherein the abraded pultrusion plates are arranged into adjacent stacks of abraded pultrusion plates, wherein each pair of adjacent layers of abraded pultrusion plates in each stack are separated by an electrically conductive interlayer.

36. A lightning protection system according to claim 35, wherein each of the abraded pultrusion plates further comprises a plurality of tows of glass fibre material (70).

37. A lightning protection system according to claim 35, wherein removing at least a part of each of the edges includes steps of: abrading a first part of the top surface (81) within a first region of the top surface (81), the first region of the top surface (81) extending from the first lateral surface (83) towards the second lateral surface (84), abrading a second part of the top surface (81) within a second region of the top surface (81), the second region of the top surface (81) extending from the second lateral surface (84) towards the first lateral surface (83), abrading a first part of the bottom surface (82) within a first region of the bottom surface (82), the first region of the bottom surface (82) extending from the first lateral surface (83) towards the second lateral surface (84), abrading a second part of the bottom surface (82) within a second region of the bottom surface (82), the second region of the bottom surface (82) extending from the second lateral surface (84) towards the first lateral surface (83).

38. A method of manufacturing a wind turbine blade shell component (38), the method comprising the steps of: providing a plurality of abraded pultrusion plates (64a-64f) obtained from a first plurality of pultrusion plates (64), wherein each pultrusion plate (64) in the first plurality of pultrusion plates comprises a top surface (81), an opposing bottom surface (82), a first lateral surface (83) and an opposing second lateral surface (84), wherein obtaining the plurality of abraded pultrusion plates includes abrading each of the first plurality of pultrusion plates by removing at least a part of each of the edges at which the top surface (81) meets the lateral surfaces (83, 84) and the edges at which the bottom surface (82) meets the lateral surfaces (83, 84), arranging a first layer of abraded pultrusion plates (164a, 164c) on a blade shell material (89) in a mould (77), arranging a first electrically conductive interlayer (131) on the first layer of abraded pultrusion plates, arranging a second layer of abraded pultrusion plates (164b, 164d) on the first interlayer (131), bonding the first and second layers of abraded pultrusion plates (164a-164d) with the blade shell material to form the blade shell component, wherein each pultrusion plate (64) in the first plurality of pultrusion plates is formed of a pultrusion fibre material comprising a plurality of tows of carbon fibre material (68), and wherein adjoining tows of carbon fibre material are provided along the lateral surfaces (83, 84) of the pultrusion plate.

39. A method according to claim 38, wherein each of the pultrusion plates further comprise a plurality of tows of glass fibre material (70).

40. A method according to claim 38, wherein removing at least a part of each of the edges at which the top surface (81) meets the lateral surfaces (83, 84) reduces a width of the top surface by 6-30 mm, such as by 10-30 mm, such as by 10-20 mm; and/or wherein removing at least a part of each of the edges at which the bottom surface (82) meets the lateral surfaces (83, 84) reduces a width of the bottom surface by 6-30 mm, such as by 10-30 mm, such as by 10-20 mm.

41. A method according to claim 38, wherein a total longitudinal length of each of the abraded parts is in the range [L.sub.p-2000 mm, L.sub.p,], where L.sub.p is a longitudinal length of the abraded pultrusion plate.

42. A method according to claim 38, wherein the lateral surfaces of each pultrusion plate are free from glass fibres.

43. A method according to claim 42, wherein said lateral surfaces free from glass fibres are obtained by providing a continuous path of adjoining tows of carbon fibre material along the lateral edges of the pultrusion plate, the continuous path of adjoining tows of carbon fibre material extending from the top surface to the opposing bottom surface of the pultrusion plate, the continuous path of adjoining tows of carbon fibre material providing an electrically conductive path throughout the vertical direction of the pultrusion plate from the top surface to the bottom surface.

44. A method according to claim 38, wherein all tows of carbon fibre material within each abraded pultrusion plate are electrically coupled to one another.

45. A method according to claim 38, wherein the distance between adjoining tows of carbon fibre material is less than 50 ?m.

46. A method according to claim 38, wherein the plurality of tows of glass fibre material and the plurality of tows of carbon fibre material form a non-random pattern, preferably a symmetrical pattern, as seen in a vertical cross section view of the pultrusion plate.

47. A method according to claim 38, wherein the abraded pultrusion plates are arranged into adjacent stacks of abraded pultrusion plates, and wherein adjoining tows of carbon fibre material together with the interlayers arranged between layers of the stacks, such as between all layers of the stacks, provide a conductive path from the top surface of the uppermost abraded pultrusion plate of a first stack of the adjacent stacks of pultrusion plates to the bottom surface of the lowermost abraded pultrusion plate in the first stack.

48. A method according to claim 38, wherein adjoining tows of carbon fibre material are provided along the top surface (81) of each pultrusion plate and wherein adjoining tows of carbon fibre material are provided along the bottom surface (82) of each pultrusion plate.

49. An abraded pultrusion plate (164a-164f, 165a), the abraded pultrusion plate having been obtained by abrading a first pultrusion plate having a top surface (81), an opposing bottom surface (82), a first lateral surface (83) and an opposing second lateral surface (84), wherein the first pultrusion plate is formed of a pultrusion fibre material comprising a plurality of tows of carbon fibre material (68), and wherein adjoining tows of carbon fibre material are provided along the entire lateral surfaces (83, 84) of the first pultrusion plate, and wherein the abrading of the first pultrusion plate to obtain the abraded pultrusion plate includes removing at least a part of each of the edges at which the top surface (81) meets the lateral surfaces (83, 84) and the edges at which the bottom surface (82) meets the lateral surfaces (83, 84) in the first pultrusion plate.

50. An abraded pultrusion plate in accordance with claim 49, wherein the abraded pultrusion plate further comprises a plurality of tows of glass fibre material (70).

51. An abraded pultrusion plate according to claim 49, wherein the lateral surfaces of the pultrusion plate are free from glass fibres, preferably by providing a continuous path of adjoining tows of carbon fibre material along the lateral edges of the pultrusion plate, the continuous path of adjoining tows of carbon fibre material extending from the top surface to the opposing bottom surface of the pultrusion plate.

52. An abraded pultrusion plate according to claim 49, wherein the plurality of tows of glass fibre material and the plurality of tows of carbon fibre material form a non-random pattern, preferably a symmetrical pattern, as seen in a vertical cross section of the pultrusion plate.

53. A reinforcing structure for a wind turbine blade, the reinforcing structure comprising layers of abraded pultrusion plates (164a-164f, 165a) according to claim 49, wherein the abraded pultrusion plates are arranged into adjacent stacks of abraded pultrusion plates, each pair of layers of abraded pultrusion plates in each stack being separated by an electrically conductive interlayer (131, 132).

54. A wind turbine blade shell component comprising a reinforcing structure in accordance with claim 53.

Description

DESCRIPTION OF THE INVENTION

[0093] The invention is explained in detail below with reference to an embodiment shown in the drawings, in which

[0094] FIG. 1 shows a wind turbine,

[0095] FIG. 2 shows a schematic view of a wind turbine blade,

[0096] FIG. 3 shows a schematic view of a cross-section of a wind turbine blade,

[0097] FIG. 4 is a schematic top view of a shell half of a wind turbine blade according to the present invention,

[0098] FIG. 5 is a schematic vertical cross section through part of a shell half with a reinforcing structure of the present invention,

[0099] FIG. 6 illustrates a pultrusion process for manufacturing the pultrusion plates of the present invention,

[0100] FIGS. 7a-7f is a schematic vertical cross sectional view of different embodiments of the pultrusion plate of the present invention,

[0101] FIG. 8 is a vertical cross sectional view of a reinforcing structure of the present invention,

[0102] FIG. 9 is a schematic vertical cross sectional view of a pultrusion plate according to another aspect of the present invention,

[0103] FIG. 10 is a schematic vertical cross sectional view of additional embodiments of the pultrusion plate of the present invention,

[0104] FIG. 11 is a schematic illustration of a lightning protection system of the present invention,

[0105] FIGS. 12a-12e illustrate provision of an abraded pultrusion plate,

[0106] FIGS. 13a-13c illustrate provision of a spar cap structure from a plurality of abraded pultrusion plates,

[0107] FIGS. 14a-14c illustrate provision of a spar cap structure from a plurality of abraded pultrusion plates,

[0108] FIG. 15 illustrates a spar cap made from a plurality of abraded pultrusion plates,

[0109] FIG. 16 illustrates a spar cap made from a plurality of abraded pultrusion plates.

DETAILED DESCRIPTION OF THE FIGURES

[0110] FIG. 1 illustrates a conventional modern upwind wind turbine according to the so-called Danish concept with a tower 4, a nacelle 6 and a rotor with a substantially horizontal rotor shaft. The rotor includes a hub 8 and three blades 10 extending radially from the hub 8, each having a blade root 16 nearest the hub and a blade tip 14 farthest from the hub 8. The rotor has a radius denoted R.

[0111] FIG. 2 shows a schematic view of a wind turbine blade 10. The wind turbine blade 10 has the shape of a conventional wind turbine blade and comprises a root region 30 closest to the hub, a profiled or an airfoil region 34 farthest away from the hub and a transition region 32 between the root region 30 and the airfoil region 34. The blade 10 comprises a leading edge 18 facing the direction of rotation of the blade 10, when the blade is mounted on the hub, and a trailing edge 20 facing the opposite direction of the leading edge 18.

[0112] The airfoil region 34 (also called the profiled region) has an ideal or almost ideal blade shape with respect to generating lift, whereas the root region 30 due to structural considerations has a substantially circular or elliptical cross-section, which for instance makes it easier and safer to mount the blade 10 to the hub. The diameter (or the chord) of the root region 30 may be constant along the entire root area 30. The transition region 32 has a transitional profile gradually changing from the circular or elliptical shape of the root region 30 to the airfoil profile of the airfoil region 34. The chord length of the transition region 32 typically increases with increasing distance rfrom the hub. The airfoil region 34 has an airfoil profile with a chord extending between the leading edge 18 and the trailing edge 20 of the blade 10. The width of the chord decreases with increasing distance r from the hub.

[0113] A shoulder 40 of the blade 10 is defined as the position, where the blade 10 has its largest chord length. The shoulder 40 is typically provided at the boundary between the transition region 32 and the airfoil region 34. FIG. 2 also illustrates the longitudinal extent L, length or longitudinal axis of the blade.

[0114] It should be noted that the chords of different sections of the blade normally do not lie in a common plane, since the blade may be twisted and/or curved (i.e. pre-bent), thus providing the chord plane with a correspondingly twisted and/or curved course, this being most often the case in order to compensate for the local velocity of the blade being dependent on the radius from the hub.

[0115] The blade is typically made from a pressure side shell part 36 and a suction side shell part 38 that are glued to each other along bond lines at the leading edge 18 and the trailing edge of the blade 20.

[0116] FIG. 3 shows a schematic view of a cross section of the blade along the line I-I shown in FIG. 2. As previously mentioned, the blade 10 comprises a pressure side shell part 36 and a suction side shell part 38. The pressure side shell part 36 comprises a spar cap 41, also called a main laminate, which constitutes a load bearing part of the pressure side shell part 36. The spar cap 41 comprises a plurality of fibre layers 42 mainly comprising unidirectional fibres aligned along the longitudinal direction of the blade in order to provide stiffness to the blade. The suction side shell part 38 also comprises a spar cap 45 comprising a plurality of fibre layers 46. The pressure side shell part 36 may also comprise a sandwich core material 43 typically made of balsawood or foamed polymer and sandwiched between a number of fibre-reinforced skin layers. The sandwich core material 43 is used to provide stiffness to the shell in order to ensure that the shell substantially maintains its aerodynamic profile during rotation of the blade. Similarly, the suction side shell part 38 may also comprise a sandwich core material 47.

[0117] The spar cap 41 of the pressure side shell part 36 and the spar cap 45 of the suction side shell part 38 are connected via a first shear web 50 and a second shear web 55. The shear webs 50, 55 are in the shown embodiment shaped as substantially I-shaped webs. The first shear web 50 comprises a shear web body and two web foot flanges.

[0118] The shear web body comprises a sandwich core material 51, such as balsawood or foamed polymer, covered by a number of skin layers 52 made of a number of fibre layers. The blade shells 36, 38 may comprise further fibre-reinforcement at the leading edge and the trailing edge. Typically, the shell parts 36, 38 are bonded to each other via glue flanges.

[0119] FIG. 4 is a schematic top view of a shell half 38 of a wind turbine blade according to the present invention, illustrating the location of a reinforcing structure 62 having a spanwise extent Se. In the illustrated embodiment, the reinforcing structure 62 comprises three adjacent stacks 66a, 66b, 66c of pultrusion plates. As seen in FIG. 4, the elongate reinforcing structure 62 extends in a substantially spanwise direction of the blade, with adjacent stacks 66a, 66b, 66c of pultrusion plates. The elongate reinforcing structure 62 has a tip end 74, closest to the tip end of the blade, and a root end 76, closest to the root end of the blade. The elongate reinforcing structure also comprises a spanwise extending front edge 78, which is closest to the leading edge 18 of the blade, and a spanwise extending rear edge 80, which is closest to the trailing edge 20 of the blade.

[0120] FIG. 5 is a schematic vertical cross section through part of a shell half with a reinforcing structure 62 of the present invention, as seen from the root end of the blade. The reinforcing structure 62, such as a spar cap, comprises a plurality of pultrusion plates 64 according to the present invention, arranged in adjacent stacks 66a-e, which are arranged on blade shell material 89 in mould 77 for the blade shell component, such as a shell half. The stacked pultrusion plates 64 are then bonded with the blade shell material 89 to form the blade shell component, such as the shell half with the spar cap. Core material 85 is arranged on either chordwise side of the reinforcing structure 62. A first shear web 50 and a second shear web 55 are placed on the spar cap 62 via respective bond lines 88. The stacks 66a-e may be covered by a carbon biax layer 86 or a carbon veil or a glass/carbon hybrid fabric or a glass/carbon hybrid veil extending towards current connection terminal 87 of a lightning protection system.

[0121] FIG. 6 illustrates a pultrusion process for manufacturing the pultrusion plates 64 of the present invention. The pultrusion process makes use of a pultrusion system 90 which comprises a portion for receiving a plurality of bobbins 92 each supplying a tow of glass fibre material 70 and a plurality of bobbins 93 each supplying a tow of carbon fibre material 68 from a creel 91. Additional reinforcement material 94 may be provided. The tows 68, 70 are pulled through guide plates 95, resin bath 96, and heated die 97 by a pulling mechanism 98. The pultrusion string 100 is cut into individual pultrusion plates 64 by cutter 99. The shaped impregnated fibres are cured and can optionally be wound onto a roll. The guide plates and/or the die may take the form of a spreader or inlet comprising multiple apertures, each aperture receiving a respective carbon fibre tow or glass fibre tow. The apertures can be spaced, and they are located so as to guide the fibre tows to form a desired pattern of glass fibre tows and carbon fibre tows in the pultrusion plates 64. The enlarged view of the pultrusion plate 64 in FIG. 6 also illustrates its longitudinal axis La and its length l. The height/thickness h and width w of the pultrusion plate are illustrated in FIG. 8, see plate 64f.

[0122] Various of the patterns of the present invention are illustrated in FIG. 7, which is a schematic vertical cross sectional view of different embodiments of the pultrusion plate 64 of the present invention, taken along the line a-a in FIG. 6. Each pultrusion plate 64 in the various embodiments illustrated in FIGS. 7a-f comprises a plurality of tows of glass fibre material 70, indicated as white elliptical shapes, and a plurality of tows of carbon fibre material 68, indicated as black elliptical shapes. As illustrated in FIG. 7a, the tows of glass fibre material 70 and the tows of carbon fibre material 68 are arranged in an array of rows 71 and columns 72 of tows, as seen in a vertical cross section of the pultrusion plate.

[0123] As illustrated in FIG. 7a, each pultrusion plate comprises a top surface 81, an opposing bottom surface 82 and two lateral surfaces 83, 84, wherein adjoining tows of carbon fibre material are provided along the lateral surfaces 83, 84. This provides respective continuous paths 67a, 67b of adjoining tows of carbon fibre material extending from the top surface 81 to the opposing bottom surface 82 of the pultrusion plate 64 along the lateral surfaces.

[0124] As seen in the various embodiments of FIG. 7, the plurality of tows of glass fibre material 70 and the plurality of tows of carbon fibre material 68 form a non-random pattern, preferably a symmetrical pattern, as seen in a vertical cross section of the pultrusion plate 64. FIG. 7a shows an embodiment where adjoining tows of carbon fibre material are only provided along the lateral surfaces 83, 84. In FIG. 7b, the carbon tows additionally extend along part of the upper and lower surfaces 81, 82, to some extent from the lateral surfaces 83, 84 towards the centre. In the embodiment of FIG. 7c, the carbon tows additionally extend along the upper and lower surfaces 81, 82 across the entire width of the pultrusion plate. The embodiment illustrated in FIG. 7d comprises several rows of adjoining carbon tows 68 along the lateral surfaces, as well as a continuous line of carbon tows extending between the lateral edges within the pultrusion plate. A similar configuration is shown in FIG. 7e, wherein the centre line is somewhat more scattered. Finally, FIG. 7f illustrates an embodiment in which several rows of adjoining carbon tows 68 are provided along the lateral surfaces, and in addition a checkerboard pattern is provided in a centre region of the pultrusion plate 64.

[0125] FIG. 8 is a schematic vertical cross sectional view of a reinforcing structure 62 of the present invention, such as a spar cap comprising three chordwise adjacent stacks 66a-c of four pultrusion plates 64 per stack. Several continuous paths of adjoining tows of carbon fibre material extend from the top surface of the reinforcing structure 62 to its bottom surface as illustrated at 67a by way of the adjoining carbon tows provided at the lateral edges of the individual plates 64. Ce is the chordwise extent of reinforcing structure.

[0126] FIG. 9 is a cross sectional view of a pultrusion plate 64 according to another aspect of the present invention. Here, adjoining tows of carbon fibre material 68 are provided along the top surface 81 and the bottom surface 82 of the pultrusion plate, whereas the lateral edges 83, 84 comprise both carbon fibre tows and glass fibre tows. Thus, a conductive path of adjoining carbon fibre tows is provided in a horizontal direction.

[0127] FIG. 10 is a schematic vertical cross sectional view of yet additional embodiments of the pultrusion plate of the present invention. Again, the plurality of tows of glass fibre material 70 and the plurality of tows of carbon fibre material 68 form a non-random pattern as seen in a vertical cross section of the pultrusion plate 64. In each of FIGS. 10a-d, adjoining tows of carbon fibre material are provided along the lateral surfaces 83, 84. Also, a continuous line of carbon tows extends through the centre, between the lateral edges of the pultrusion plate. Furthermore, one or more vertically extending columns of adjoining tows of carbon fibre material are provided closer to the middle of the pultrusion plate, some of which extend all the way from the top surface to the bottom surface, see FIGS. 10a, d, and some of which extend only to the top surface, but not to the bottom surface, see FIG. 10c. FIG. 10b shows an embodiment wherein a vertical column extends at the centre of the plate, however, without extending all the way to the top surface or to the bottom surface.

[0128] FIG. 11 is a schematic illustration of a lightning protection system of the present invention. The lightning protection system 102 comprises a lightning conductor 104, preferably a down conductor, disposed at least partially in the interior of the blade 10. A tip lightning receptor 106 and two side lightning receptors 107, 108 are disposed on or in one or more of the outer surfaces of the blade 10, wherein the electrically conductive lightning receptors 106, 107, 108 are electrically connected to a spar cap 62 of the present invention.

[0129] FIGS. 12a-12e illustrate obtaining an abraded pultrusion plate from an unabraded pultrusion plate. FIG. 12a illustrates a perspective view of a pultrusion plate 64 similar to the pultrusion plate 64 shown in FIG. 7d. For simplicity, the individual tows are not shown. FIG. 12b is the vertical cross section of the pultrusion plate in FIG. 12a, showing the carbon fibre material 68 in black and the glass fibre material 70 hatched.

[0130] The pultrusion plate shown in FIGS. 12a-12b is unabraded and has a rectangular vertical cross-section. The top surface 81 meets the lateral surfaces 83 and 84, forming two corresponding edges 121 and 122. Similarly, bottom surface 82 meets the lateral surfaces 83 and 84, forming two corresponding edges 123 and 124. The width W.sub.1 of the top surface 81 (and the bottom surface (82)) is illustrated in FIG. 12b.

[0131] FIG. 12c shows an abraded pultrusion plate 164a resulting from abrading the edges 121-124. In this example, the abrading results in rounded edges 121a-124a as shown in FIG. 12c. The removal of parts of the edges shortens the top surface 81 and the bottom surface 82 and the lateral surfaces 83, 84 as can be seen by comparing FIG. 12b with FIG. 12c.

[0132] The abrading may alternatively result in flattened edges, in a sense creating an additional facet or additional surface 121b-124b at each edge, as shown on the abraded pultrusion 165a in FIG. 12d. As above, the width of the top surface 81 and the bottom surface 82 is shortened by the removal of parts of the edges.

[0133] Flattened edges can be simpler to produce since they can be made by cutting using for instance a rotating blade travelling along each of the edges. It is also possible to abrade for instance by grinding, planing, or sanding.

[0134] Abrading the edges makes it easier for instance to arrange the pultrusion plates in adjacent stacks, especially when the surface is sloped, in which case the edges of the adjacent pultrusion plates may come into contact with one another.

[0135] FIG. 12e illustrates an upper part of the abraded pultrusion plate 165a and shows the width W.sub.1 of the top surface 81 and bottom surface 82 before abrading and the width W.sub.2 of the top surface 81 and bottom surface 82 after abrading. Typically, the abrading reduces the width by 10-20 mm, that is, W.sub.1-W.sub.2 is in the range 10-20 mm. Typically, the reduction is distributed evenly between the two edges 121, 122 (see FIG. 12b), i.e. 5-10 mm is removed from each edge. The same applies to the bottom surface.

[0136] Removing parts of each of the edges is typically performed separately and may have been performed through the steps of: [0137] abrading a first part of the top surface 81 within a first region of the top surface 81, the first region of the top surface 81 extending from the first lateral surface (83 towards the second lateral surface 84, [0138] abrading a second part of the top surface 81 within a second region of the top surface 81, the second region of the top surface 81 extending from the second lateral surface 84 towards the first lateral surface 83, [0139] abrading a first part of the bottom surface 82 within a first region of the bottom surface 82, the first region of the bottom surface 82 extending from the first lateral surface 83 towards the second lateral surface 84, [0140] abrading a second part of the bottom surface 82 within a second region of the bottom surface 82, the second region of the bottom surface 82 extending from the second lateral surface 84 towards the first lateral surface 83.

[0141] In some embodiments, the abrading has a total longitudinal length or extent of at least half a length of the pultrusion plate. In some embodiments, the edges have been abraded along the entire length of the pultrusion plate. In some embodiments, abrading is not performed from an end of the pultrusion plate up to a distance in the range 100-1000 mm from said end, in particular in case the pultrusion plate is or will be chamfered at the end or ends. Abrading the end might compromise the strength of the chamfered end.

[0142] FIGS. 13a-13c illustrate a method for laying up abraded pultrusion plates for a wind turbine blade shell component, such as a spar cap. First, as shown in FIG. 13a, a first layer of one or more abraded pultrusion plates is arranged on a surface, such as on blade shell material arranged in a mould. In this case, the first layer contains a single abraded pultrusion plate 164a. An electrically conductive interlayer 131 is then placed on the first layer, as shown in FIG. 13b. Next, a second layer of one or more abraded pultrusion plates is place on the interlayer 131, in this case a single abraded pultrusion plate 164b. Subsequently, additional material may be arranged, as needed, and the layers are then bonded together with the surface, thereby forming the wind turbine blade shell component.

[0143] The interlayer 131 separates the two layers but provides electrical contact between the abraded pultrusion plates 164a and 164b by being in electrical contact with carbon fibre material in both abraded pultrusion plates.

[0144] The spar cap may include further abraded pultrusion plates, as shown in FIGS. 14a-14c. FIG. 14a illustrates arranging two abraded pultrusion plates 164a and 164c adjacent one another in a first layer. An electrically conductive interlayer 131 is arranged on top of the first layer of abraded pultrusion plates, as shown in FIG. 14b. Next, a second layer of abraded pultrusion plates 164b and 164d are arranged on the interlayer 131, forming a second layer.

[0145] The interlayer 131 in FIG. 14c separates the two layers but provides electrical contact between all the abraded pultrusion plates 164a-164d by being in electrical contact with carbon fibre material in the abraded pultrusion plates.

[0146] FIG. 15 illustrates the structure in FIG. 14c with an additional interlayer 132 placed on the second layer of abraded pultrusion plates and a third layer of abraded pultrusion plates 164e and 164f arranged on the second interlayer 132, resulting in two stacks of three abraded pultrusion plates.

[0147] The interlayers 131 and 132 provide electrical connection between all abraded pultrusion plates in the spar cap structure by electrically connecting the bottom surfaces of pultrusions in one layer, such as 164b and 164d, with the top surface of pultrusions in the layer below, such as 163a and 164c. Furthermore, electrical connection between the layers is established by the interlayers 131, 132. This is illustrated by the arrows going through carbon fibre material comprised in pultrusions 164c, 164b, 164d, 164e, 164f through the interlayers 131 and 132.

[0148] FIG. 16 illustrates a structure with four stacks of three abraded pultrusion plates, with an additional electrically conductive interlayer 133 separating the third and the fourth layer as counted from the layup surface.

[0149] The invention is not limited to the embodiments described herein and may be modified or adapted without departing from the scope of the present invention.

LIST OF REFERENCE NUMERALS

[0150] 4 tower [0151] 6 nacelle [0152] 8 hub [0153] 10 blades [0154] 14 blade tip [0155] 16 blade root [0156] 18 leading edge [0157] 20 trailing edge [0158] 30 root region [0159] 32 transition region [0160] 34 airfoil region [0161] 36 pressure side shell part [0162] 38 suction side shell part [0163] 40 shoulder [0164] 41 spar cap [0165] 42 fibre layers [0166] 43 sandwich core material [0167] 45 spar cap [0168] 46 fibre layers [0169] 47 sandwich core material [0170] 50 first shear web [0171] 51 core member [0172] 52 skin layers [0173] 55 second shear web [0174] 56 sandwich core material of second shear web [0175] 57 skin layers of second shear web [0176] 60 filler ropes [0177] 62 reinforcing structure [0178] 64 pultrusion plate [0179] 66 stack of pultrusion plates [0180] 67 path [0181] 68 tow of carbon fibre material [0182] 70 tow of glass fibre material [0183] 71 row of tows [0184] 72 column of tows [0185] 74 tip end of reinforcing structure [0186] 76 root end of reinforcing structure [0187] 77 mould [0188] 78 front edge of reinforcing structure [0189] 80 rear edge of reinforcing structure [0190] 81 top surface of pultrusion plate [0191] 82 bottom surface of pultrusion plate [0192] 83 first lateral surface of pultrusion plate [0193] 84 second lateral surface of pultrusion plate [0194] 85 core material [0195] 86 carbon biax layer [0196] 87 current connection terminal [0197] 88 bond line [0198] 89 shell material [0199] 90 pultrusion system [0200] 91 creel [0201] 92 bobbin with tow of glass fibre material [0202] 93 bobbin with tow of carbon fibre material [0203] 94 additional reinforcement material [0204] 95 guide plate [0205] 96 resin bath [0206] 97 heated die [0207] 98 pulling mechanism [0208] 99 cutter [0209] 100 pultrusion string [0210] 102 lightning protection system [0211] 104 down conductor [0212] 106 tip receptor [0213] 107 side receptor [0214] 108 side receptor [0215] 121-124: pultrusion plate edges [0216] 121a-124a: rounded edges from abrading [0217] 121b-124b: flattened edges/additional surfaces from abrading [0218] 131-132: electrically conductive interlayers [0219] 164a-164f: abraded pultrusion plates [0220] 165a: abraded pultrusion plate with flattened edges/additional surfaces [0221] L length [0222] l length of pultrusion plate [0223] w width of pultrusion plate [0224] h height of pultrusion plate [0225] La longitudinal axis of pultrusion plate [0226] r distance from hub [0227] R rotor radius [0228] Se spanwise extent of reinforcing structure [0229] Ce chordwise extent of reinforcing structure