Wind turbine rotor blade spars cap with equipotential bonding

Abstract

A wind turbine rotor blade spars cap has a length and includes: a stack comprising a plurality of conductive material layers and at least one intermediate layer, wherein each conductive material layer has a length along the length of the spars cap in a first direction, wherein the intermediate layer is disposed between adjacent conductive material layers, wherein the intermediate layer comprises a fibrous fabric material having: a first edge extending in the first direction; a conductive portion having conductive fibers oriented in the first direction; a first boundary portion between the first edge and the conductive portion having a plurality of non-conductive fibers oriented in the first direction but without conductive fibers oriented in the first direction; and cross fibers oriented to cross conductive and non-conductive fibers, and wherein the intermediate layer is bonded to and electrically connected to adjacent conductive material layers so as to be equipotentially bonded to adjacent conductive material layers via the conductive portion of the intermediate layer.

Description

Technical Field

[0001] This invention relates to a wind turbine rotor blade spar cap, a fiber fabric material for the wind turbine rotor blade spar cap, and a method for manufacturing the wind turbine rotor blade spar cap. Background Technology

[0002] Wind turbines convert the kinetic energy of wind into electrical energy. A generator converts the wind energy captured by a rotor with one or more rotor blades into electrical energy that is typically supplied to the public power grid. The generator, along with various components required to operate and optimize the performance of the wind turbine, is housed in a nacelle. The tower supports the loads provided by the nacelle and rotor. In a horizontal axis wind turbine (HAWT), the rotor blades extend radially outward from a central hub that rotates about a generally horizontally aligned longitudinal axis. In operation, the blades are configured to interact with the passing airflow to generate lift, which causes the rotor to rotate in a plane substantially perpendicular to the direction of the wind. Conventional rotor blades consist of a hull and one or more inner spars within a hollow space defined by the hull. The spars are used to transfer loads from the rotating blades to the hub of the wind turbine. These loads include tensile and compressive loads along the length of the blade caused by the circular motion of the blade, and loads caused by the wind along the thickness of the blade (i.e., from the windward side to the leeward side of the blade). The spar typically has a hollow tubular cross-section, such as a roughly rectangular hollow tubular cross-section, or a beam cross-section, such as an I-beam, C-beam, H-beam, Y-beam, X-beam, etc., wherein one or more shear webs extend between the spar caps. The spar caps can be integrated into or attached to the outer shell.

[0003] The spar cap may comprise pultruded fiber material strips. Pultrusion is a continuous method similar to extrusion molding, in which fibers are drawn through a liquid resin source and then heated in an open chamber where the resin cures. The resulting cured fiber material has a constant cross-section, but because the method is continuous, the material can be cut to arbitrary lengths once formed. WO2013 / 087078 describes a wind turbine blade with an elongated reinforcing structure comprising a stack of pultruded fiber composite strips. The pultruded fibers are carbon fibers and extend almost the entire length of the blade from root to tip.

[0004] Over the past few years, the general trend in the wind turbine industry has been to make wind turbine blades longer. The longer the blades, the larger the rotor and the more wind energy can be captured, thus improving the efficiency of a single wind turbine.

[0005] Wind turbines are susceptible to lightning strikes. Wind turbines typically include a lightning protection system that electrically connects the turbine components to the ground. Blades, especially the blade tips, are particularly vulnerable to lightning strikes. Therefore, blades typically include a metal foil or surface protective layer (SPL) bonded to the outer casing near the blade's outer surface. The metal foil may cover only a portion or substantially the entire outer surface of the blade. Alternatively, the lightning protection system may include one or more discrete lightning receivers. The lightning receivers on the metal foil and / or blades are electrically connected to the ground via a tower.

[0006] Although lightning strikes have a natural tendency to travel along the outer surface of structures (such as rotor blades) due to their high frequency, the presence of conductive fibers in the blade casing can cause undesirable discharges when a lightning strike occurs, potentially damaging the blade casing. This problem can be exacerbated when the conductive fibers extend along a considerable length of the rotor blade, especially for long blades.

[0007] To reduce the possibility of high potentials between adjacent pultruded material strips, conductive interweaving can be provided between the pultruded material strips to achieve equipotential bonding. However, when the conductive interweaving is made of fabric, the conductive fibers may separate from the main body of the fabric during manufacturing, potentially creating undesirable electrical connections with nearby parts. Summary of the Invention

[0008] A first aspect of the invention provides a spar cap for a wind turbine rotor blade, the spar cap having a length and comprising: a stack including a plurality of conductive material layers and at least one intermediate layer, wherein each of the conductive material layers has a length along the length of the spar cap in a first direction, wherein the intermediate layer is disposed between adjacent conductive material layers, wherein the intermediate layer comprises a fibrous fabric material having: a first edge extending in the first direction; a conductive portion having conductive fibers oriented in the first direction; a first boundary portion between the first edge and the conductive portion having a plurality of non-conductive fibers oriented in the first direction but not conductive fibers oriented in the first direction; and cross fibers oriented to cross the conductive fibers and the non-conductive fibers, and wherein the intermediate layer is bonded to and electrically connected to the adjacent conductive material layer so as to be equipotentially bonded to the adjacent conductive material layer via the conductive portion of the intermediate layer.

[0009] In summary, fibrous fabric materials can be used to facilitate the infusion of resin matrix material between conductive material strips, thereby bonding the conductive material strips together. By providing conductive portions of the fibrous fabric material, adjacent conductive material layers can bond at the same potential, thus preventing unwanted discharges or arcing within the spar cap. The boundary portions provide a buffer, ensuring that if the fibers separate from the bulk material into loose fibers during resin infusion or layup of the blade material, the loose fibers are likely non-conductive, thus preventing undesirable electrical connections.

[0010] The first boundary portion may have a width perpendicular to the first direction, and the width of the first boundary portion is at least 5 millimeters.

[0011] Conductive fibers can be carbon fibers.

[0012] All conductive fibers in the fibrous fabric material can be oriented in the first direction.

[0013] Non-conductive fibers can be glass fibers. In other instances, they can be natural fibers.

[0014] The cross fibers can be non-conductive cross fibers, and optionally, the non-conductive cross fibers can be glass fibers or non-conductive natural fibers.

[0015] The cross fibers can be oriented perpendicular to the first direction. In another example, the cross fibers can be oriented at an angle to the first direction, for example, ±45 degrees.

[0016] The conductive material may include pultruded fiber composites, preferably carbon fiber reinforced plastics.

[0017] The spar cap of a wind turbine rotor blade may also include alternating layers of conductive material and an intermediate layer.

[0018] The fibrous fabric material may further include: a second edge oriented in a first direction, the second edge being opposite to the first edge; and a second boundary portion between the second edge and the conductive portion, the second boundary portion having a plurality of non-conductive fibers oriented in the first direction and no conductive fibers oriented in the first direction.

[0019] The second boundary portion may have a width perpendicular to the first direction, and the width of the second boundary portion may be at least 5 millimeters.

[0020] The fibrous fabric material can be woven or sewn.

[0021] According to a second aspect of the invention, a wind turbine rotor blade is provided, the wind turbine rotor blade including at least one wind turbine rotor blade spar cap according to the first aspect.

[0022] A third aspect of the invention provides a method for manufacturing a sparsity cap for a wind turbine rotor blade, the method comprising: providing a plurality of conductive material layers, each layer having a length along a length of the sparsity cap in a first direction; placing an intermediate layer between adjacent conductive material layers to form a stack, the intermediate layer comprising a fibrous fabric material having: a first edge extending in the first direction; a conductive portion having conductive fibers oriented in the first direction; a first boundary portion between the first edge and the conductive portion having a plurality of non-conductive fibers oriented in the first direction but not conductive fibers oriented in the first direction; and cross fibers oriented to cross the conductive fibers and the non-conductive fibers; electrically connecting the intermediate layer to the adjacent conductive material layer to bond the adjacent conductive material layer equipotentially via the conductive portion of the intermediate layer; and curing the stack to mechanically bond the intermediate layer to the adjacent conductive material layer.

[0023] The method may also include infusing the pile with resin prior to curing.

[0024] The wind turbine rotor blade spar cap manufactured by the method of the third aspect of the present invention can be the wind turbine rotor blade spar cap of the first aspect of the present invention.

[0025] A fourth aspect of the invention provides a fibrous fabric material for a spar cap on a wind turbine blade, the fibrous fabric material having: a length in a first direction; a width perpendicular to the length, the width being shorter than the length; a first edge extending in the first direction; a conductive portion having conductive fibers oriented in the first direction; a first boundary portion between the first edge and the conductive portion having a plurality of non-conductive fibers oriented in the first direction but no conductive fibers oriented in the first direction; and cross fibers oriented to cross the conductive fibers and the non-conductive fibers.

[0026] The fourth aspect of the fibrous fabric material is particularly suitable for mechanically and equipotentially bonding adjacent conductive material strips, and can have the advantages described above with reference to the first aspect.

[0027] Alternatively, the fiber fabric material of the fourth aspect may have properties substantially similar to those optional properties described above for the fiber fabric material of the wind turbine rotor blade spars cap with reference to the first aspect. Attached Figure Description

[0028] Embodiments of the present invention will now be described with reference to the accompanying drawings, in which:

[0029] Figure 1 A wind turbine is shown;

[0030] Figure 2 A wind turbine blade is shown;

[0031] Figure 3 It shows along Figure 2 The cross-section of AA shows the shell and spar structure;

[0032] Figure 4 It shows Figure 3 Details of the outer shell, spar caps, and shear webs in section B;

[0033] Figure 5 A schematic cross-section of the layered stack forming the spar cap is shown;

[0034] Figure 6a A known fibrous fabric material is schematically shown prior to resin infusion;

[0035] Figure 6b A known fibrous fabric material is schematically shown after resin infusion;

[0036] Figure 7a The diagram schematically illustrates the fibrous fabric material prior to resin infusion; and

[0037] Figure 7b The diagram schematically illustrates the fibrous fabric material after resin infusion. Detailed Implementation

[0038] In this specification, terms such as “leading edge,” “trailing edge,” “pressure surface,” “suction surface,” “thickness,” and “chord” are used. While these terms are well known and understood by those skilled in the art, definitions are provided below to avoid ambiguity.

[0039] The term "leading edge" refers to the edge of a blade that is located at the front of the blade as it rotates in the normal direction of rotation of the wind turbine rotor.

[0040] The term "tail edge" refers to the edge of a wind turbine blade, which is located at the rear of the blade as the blade rotates in the normal direction of rotation of the wind turbine rotor.

[0041] The chord of a blade is the straight-line distance from the leading edge to the trailing edge in a given cross section perpendicular to the blade's span direction.

[0042] The pressure surface (or windward surface) of a wind turbine blade is the surface between the leading and trailing edges, which has a higher pressure than the suction surface of the blade during use.

[0043] The suction surface (or downwind surface) of a wind turbine blade is the surface between the leading and trailing edges. During use, the pressure acting on this surface will be lower than the pressure surface.

[0044] The thickness of a wind turbine blade is measured perpendicular to the blade chord and is the maximum distance between the pressure surface and the suction surface in a given cross section perpendicular to the blade span direction.

[0045] The term "wingspan direction" refers to the direction from the root end of a wind turbine blade to the tip end, and vice versa. When wind turbine blades are mounted on a wind turbine hub, the wingspan direction and radial direction will be substantially the same.

[0046] The term "fiber" as used in this specification refers to a bundle of filaments and may also refer to components also called yarn, roving, filament bundle, or ply.

[0047] The term "edge" is used in this specification to refer to a portion of the material. Note that the edge of the material is the physical limitation of fibers oriented along the edge direction. The fringe of the material (which may include fibers extending through and beyond the edge) may extend beyond the edge of the material. In other words, the edge of the material oriented along a first direction may be defined by the outermost fibers of the material oriented along the first direction.

[0048] Figure 1 A wind turbine 10 is shown, which includes a tower 12 mounted on a base and a nacelle 14 located at the apex of the tower 12. The wind turbine 10 shown here is an onshore wind turbine, in which case the base is buried in the ground; however, the wind turbine 10 could be an offshore facility, in which case the base would be provided by a suitable offshore platform.

[0049] Rotor 16 is operatively coupled via a gearbox to a generator (not shown) housed within nacelle 14. Rotor 16 includes a central hub 18 and a plurality of rotor blades 20 projecting outward from the central hub 18. It should be noted that the wind turbine 10 is a conventional type of horizontal axis wind turbine (HAWT), such that rotor 16 is mounted at nacelle 12 to rotate about a substantially horizontal axis defined at the center of hub 18. Although Figure 1 The example shown has three blades, but those skilled in the art will recognize that other numbers of blades are also possible.

[0050] When wind blows towards the wind turbine 10, the blades 20 generate lift, which causes the rotor 16 to rotate, which in turn causes the generator in the nacelle 14 to generate electricity.

[0051] Figure 2A wind turbine blade 20 for such a wind turbine is shown. Each blade 20 has a root end 32 near the hub 18 and a tip end 30 away from the hub 18. The blades 20 are arranged to extend away from the hub 18 in the spanwise direction S. A leading edge 26 and a trailing edge 28 extend between the root end 32 and the tip end 30, and each blade 20 has a corresponding aerodynamic high-pressure surface 22 (i.e., pressure surface) and aerodynamic low-pressure surface (i.e., suction surface) 24 extending between the leading and trailing edges of the blade 20.

[0052] Each blade has a substantially circular cross-section near its root end 32, because the blade near the root must have sufficient structural strength to support the blades outside this cross-section and transfer the load to the hub 18. The blade 20 transitions from a circular profile to an airfoil profile that moves from the root end 32 toward the tip end 30. The blade may have a "shoulder," which is the widest part of the blade with its maximum chord. The blade 20 has an airfoil cross-section profile with a thickness that gradually decreases toward the tip end 30.

[0053] like Figure 3 As shown, Figure 3 This is a cross-sectional view of blade 20 taken along line AA. The wind turbine blade 20 includes an outer blade shell formed by an upper portion 42 and a lower portion 44, which together define a hollow internal space 34, wherein a shear web 40 extends internally between the upper portion 42 and the lower portion 44 of the blade shell. The blade shell portion may be two half-shells 42, 44, which are separately molded before being joined together (at the leading edge 26 and trailing edge 28) to form blade 20. It should be understood that the blade shells 42, 44 do not necessarily need to be formed as two half-shells subsequently joined together, but can be formed as an integral shell structure together with the shear web 40 in a "one-injection" single-shell process. The blade shell may include laminated composite materials, such as glass fiber and / or carbon fiber.

[0054] Figure 4 A detailed view of region B is shown, in which the shear web 40 meets the blade shell 44. The spar cap 100 can be integrated into the shell 44, as... Figure 4 As shown, it may be attached to the outer shell 44. The spar cap 100 is an elongated reinforcing structure and may extend substantially along the entire span of the blade 20 from the root end 32 to the tip end 30. The spar cap 100 comprises a conductive material, such as carbon fiber. For example, the spar cap may comprise a pultruded strip of fibrous material, such as a pultruded carbon fiber composite or other carbon fiber reinforced plastic material.

[0055] The spar cap 100 may include a stack of conductive material layers. A shear web 40 may be adhesively bonded to the inner surface of the spar cap 100. The outer surface of the spar cap 100 may be adjacent to the lightning conductor 46 in the outer surface of the blade shell 44. Figure 4 As shown, the lightning conductor can be in the form of a metal foil 46, which can be separated from the outer surface of the spar cap 100 by one or more layers of insulating material 48 (e.g., glass fiber reinforced plastic). Another layer or more of glass fiber reinforced plastic can be disposed on the outside of the metal foil 46. These layers together form the outer skin 48 of the blade shell 44. Another layer or more of glass fiber reinforced plastic provides the inner skin 45 of the blade shell 44, with a core material between the outer skin 48 and the inner skin 45. The core material can be a lightweight structural foam, although other core materials (such as wood, especially balsa wood, and honeycomb structures) can also be used alternatively to provide a lightweight core material. It is understood that almost identical connections can be formed between the shear web 40 and the other side of the blade shell 42.

[0056] Blade material is laid in a wind turbine blade shell mold, and then resin is poured into them to bond the blade material together. As is known in the art, the blade material is covered with a sealed vacuum bag (which is then evacuated), and resin is then poured into the blade material. The resin is then cured, which can be done at high temperatures. This is known as the Vacuum Assisted Resin Transfer Molding (VARTM) process.

[0057] Figure 5 A cross-sectional view of the spar cap 100 before resin infusion is shown, the cross-section being cropped so that it is viewed along the wingspan. The spar cap 100 has alternating layers 102 of conductive material, which may be pultruded carbon fiber strips, sandwiched with an intermediate layer 104 of fibrous fabric material. The pultruded carbon fiber strips 102 provide structural strength to the spar cap 100. However, resin is difficult to infuse between the strips during the infusion process. The intermediate fibrous fabric layer 104 forms defined gaps between the strips 102, allowing resin to be infused between the strips. Therefore, the intermediate layer 104 acts as an infusion-promoting layer between the strips. The pultruded strips 102 are then bonded together so that the spar cap 100 can form an integral structural component. The intermediate layer 104 helps ensure proper adhesion between the pultruded strips during the infusion process.

[0058] The pultruded strips 102 can be stacked and arranged as follows: Figure 5 As shown, the spar cap can be formed by stacking two or more adjacent strips. This is advantageous when a curved spar cap is required.

[0059] The intermediate layer 104 can be wider than the pultruded carbon fiber strip 102 in the tangential direction. Therefore, when the intermediate layer 104 is laid, its edges can be spaced apart from the pultruded strip 102. This accommodates misalignment when the intermediate layer 104 is placed on the carbon fiber strip 102.

[0060] After the wing spar cap 100 is cured, a cured wing spar cap can be formed.

[0061] Due to the conductive properties of carbon fiber, potential differences between the pultruded carbon fiber strips 102 must be avoided. Potential differences can be detrimental, as they can cause arcing within the spar cap 100, potentially damaging it. Therefore, it is desirable for the interlayer 104 to be conductive throughout its thickness, allowing the pultruded carbon fiber strips 102 to bond at the same potential, thereby avoiding potential differences.

[0062] Figure 6a A schematic plan view of a known fibrous fabric material 200 prior to resin infusion is shown. The fibrous fabric material comprises carbon fiber strands 202 oriented in both a first direction S and an intersecting direction perpendicular to the first direction. When the fibrous fabric material is within the sparsity cap of a wind turbine blade, the first direction S can be the spanwise direction. Figure 6a As shown, the fibrous fabric material 200 can extend further in the spanwise direction S than in the vertical chordwise direction. Therefore, the length of the fibrous fabric material 200 in the first spanwise direction S can be longer than its width in the vertical chordwise direction.

[0063] The edge E of the fabric material 200 can be Figure 6a As seen in the image, the edge E is defined by the outermost fiber 202 oriented along the first direction S, and the spike formed by the ends of the intersecting fibers 202 protrudes further than the edge.

[0064] Figure 6b The diagram shows a fiber fabric material 200 after resin infusion, wherein an infused fiber fabric material 300 is formed. It should be understood that the infused fiber fabric material 300 can be within the spar cap of a wind turbine blade, therefore... Figure 6b This can be considered a cross-sectional view of the spar cap of a wind turbine blade.

[0065] The infused fiber fabric material 300 has a reference Figure 6a The carbon fiber 202 and matrix material 304, such as epoxy resin, can be applied to the fibrous fabric material via resin infusion. However, due to the nature of the fabric material, during the infusion process, fibers may slip off adjacent fibers and may become loose fibers 202a, such as... Figure 6bAs shown. This can be disadvantageous if the loose fiber 202a is conductive, as it can electrically connect the fibrous fabric material to adjacent structures, such as heating elements used for de-icing blades, or any other electrically sensitive components. Furthermore, even without forming electrical connections with adjacent components, the unpredictable nature of the loose fiber can allow an electric arc to occur through the matrix material, such that during a lightning strike, the loose fiber 202a can generate an arc to itself or to the body of the fibrous fabric material 300.

[0066] Typically, when loose fibers such as loose fibers 202a are identified, the fibers must be removed by cutting out a portion of the matrix material containing the loose fibers, and the blades may need to be repaired.

[0067] To mitigate the problems caused by loose fibers, the inventors provide a novel intermediate layer 104 in the form of a fiber fabric material 400, such as... Figure 7a As shown. The fiber fabric material 400 has conductive fibers 402 oriented along a first direction S. The conductive fibers 402 can be carbon fibers. When the fiber fabric material 400 is laid inside the spar cap of a wind turbine blade, the first direction S can be the wingspan direction. The conductive fibers 402 are arranged adjacent to each other on the conductive portion C of the material 400. The material 400 also has a boundary portion B adjacent to the edge of the fiber fabric material 400. The boundary portion B is arranged between the conductive fibers 402 oriented along the first direction S and the edge E of the material 400. The boundary portion B contains non-conductive fibers 404 oriented along the first direction S (as shown by the dashed line), and the boundary portion does not contain conductive fibers.

[0068] Edge E has no conductive fibers. As described above, edge E, oriented along the first direction S, is defined by the outermost fiber oriented along the first direction S, said outermost fiber being a non-conductive fiber 404. The tuft formed by the interlaced fibers 406 can protrude beyond edge E.

[0069] The fibrous fabric material 400 also has cross fibers 406 oriented perpendicular to the first direction S. The cross fibers 406 can be non-conductive fibers, such as glass fibers, and the non-conductive nature of the cross fibers 406 also means that when the cross fibers 406 are pulled out to become loose fibers, the loose fibers are not conductive fibers and therefore should not form undesirable electrical connections.

[0070] The fibrous fabric material 400 can be woven or sewn. Sewn materials can be advantageous because they can be laid flatter than woven materials, thereby improving the structure of the layers within the wing cap 100. However, woven materials may be advantageous because the textile properties of the conductive fibers 402 can improve conductivity through the thickness of the fibrous fabric material 400.

[0071] Figure 7b The illustration shows an infused fibrous fabric material 500, through which a matrix material 504 has been infused. The resin infusion process can be substantially similar to the one described above. Figure 6b The process is described. In this case, loose wires 404a are formed during resin infusion. However, since the loose wires 404a are non-conductive, the possibility of forming unwanted electrical connections is reduced.

[0072] The width of the first boundary portion B (which is the boundary portion at the two edges of the material oriented along the wingspan direction, having a width in the chord direction perpendicular to the wingspan direction) can be at least 5 mm. This is advantageous where multiple loose lines can be formed from one side of the material. For this purpose, each boundary portion can include multiple non-conductive fibers oriented along the first direction, optionally including at least 5 non-conductive fibers oriented in the first direction. By providing a wider boundary portion with a larger number of non-conductive lines, the possibility of undesirable electrical connections formed by loose lines is further reduced.

[0073] By having non-conductive boundary portions adjacent to the two edges E, the fabric material 500 can be laid without knowing its orientation and can avoid unwanted electrical connections from either edge.

[0074] The fibrous fabric material 500 may have at least 10 (optionally at least 30) conductive fibers oriented in a first direction within the conductive portion C. This can provide a high level of conductivity across the entire material thickness to ensure equipotential bonding between adjacent pultruded carbon fiber strips. Therefore, the conductive fibers may extend over a width of at least 10 mm (preferably at least 130 mm).

[0075] Although the invention has been described above with reference to one or more preferred embodiments, it should be understood that various changes or modifications may be made without departing from the scope of the invention as defined by the appended claims.

Claims

1. A wind turbine rotor blade spars cap (100), the spars cap having a length and comprising: A stack comprising multiple conductive material layers (102) and at least one intermediate layer (104), Each of the conductive material layers (102) has a length along the length of the spar cap (100) in a first direction. The intermediate layer (104) is arranged between adjacent conductive material layers (102). The intermediate layer (104) includes a fiber fabric material (400) having: A first edge (E) extends in the first direction; A conductive portion (C) having conductive fibers (402) oriented in the first direction. A first boundary portion (B) between the first edge (E) and the conductive portion (C) has a plurality of non-conductive fibers (404) oriented in the first direction and no conductive fibers oriented in the first direction; and Cross-fiber (406), which is oriented to cross the conductive fiber (402) and the non-conductive fiber (404), and The intermediate layer (104) is bonded to and electrically connected to the adjacent conductive material layer (102) so that the adjacent conductive material layer is bonded at the same potential via the conductive portion (C) of the intermediate layer.

2. The wind turbine rotor blade spars cap according to claim 1, wherein, The first boundary portion has a width perpendicular to the first direction, and the width of the first boundary portion is at least 5 millimeters.

3. The wind turbine rotor blade spars cap according to claim 1 or 2, wherein, The conductive fiber is carbon fiber.

4. The wind turbine rotor blade spars cap according to claim 1 or 2, wherein, All the conductive fibers of the fiber fabric material are oriented in the first direction.

5. The wind turbine rotor blade spars cap according to claim 1 or 2, wherein, The non-conductive fiber is glass fiber.

6. The wind turbine rotor blade spars cap according to claim 1 or 2, wherein, The cross fibers are non-conductive cross fibers.

7. The wind turbine rotor blade spars cap according to claim 1 or 2, wherein, The cross fibers are oriented perpendicular to the first direction.

8. The wind turbine rotor blade spars cap according to claim 1 or 2, wherein, The conductive material includes pultruded fiber composite materials.

9. The wind turbine rotor blade spars cap according to claim 1 or 2, wherein, The wind turbine rotor blade spar cap also includes alternating layers of conductive material and the intermediate layer.

10. The wind turbine rotor blade spars cap according to claim 1 or 2, wherein, The fibrous fabric material further includes: a second edge oriented in the first direction, the second edge being opposite to the first edge; and a second boundary portion between the second edge and the conductive portion, the second boundary portion having a plurality of non-conductive fibers oriented in the first direction and no conductive fibers oriented in the first direction.

11. The wind turbine rotor blade spars cap according to claim 10, wherein, The second boundary portion has a width perpendicular to the first direction, and the width of the second boundary portion is at least 5 millimeters.

12. The wind turbine rotor blade spars cap according to claim 1 or 2, wherein, The fibrous fabric material is woven or sewn.

13. The wind turbine rotor blade spars cap according to claim 8, wherein, The fiber composite material is carbon fiber reinforced plastic.

14. The wind turbine rotor blade spars cap according to claim 6, wherein, The non-conductive cross-fibers are glass fibers.

15. A wind turbine rotor blade comprising at least one wind turbine rotor blade spar cap according to any one of the preceding claims.

16. A method for manufacturing a sparsity cap for a wind turbine rotor blade, the method comprising: Multiple conductive material layers are provided, each layer having a length along the length of the spar cap in a first direction; An intermediate layer is placed between adjacent conductive material layers to form a stack, the intermediate layer comprising a fibrous fabric material having: A first edge, which extends in the first direction; A conductive portion having conductive fibers oriented in the first direction; In the first boundary portion between the first edge and the conductive portion, the first boundary portion has a plurality of non-conductive fibers oriented in the first direction and no conductive fibers oriented in the first direction; as well as Crossed fibers, which are oriented to cross the conductive fibers and the non-conductive fibers; The intermediate layer is electrically connected to the adjacent conductive material layer so that the adjacent conductive material layer is equipotentially bonded via the conductive portion of the intermediate layer. as well as The stack is solidified to mechanically bond the intermediate layer to the adjacent conductive material layer.

17. A fiber fabric material for a spar cap on a wind turbine blade, the fiber fabric material having: Length in the first direction; A width perpendicular to the length, which is shorter than the length; A first edge, which extends in the first direction; A conductive portion having conductive fibers oriented in the first direction; In the first boundary portion between the first edge and the conductive portion, the first boundary portion has a plurality of non-conductive fibers oriented in the first direction and no conductive fibers oriented in the first direction; as well as Crossed fibers, which are oriented to cross the conductive fibers and the non-conductive fibers.

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