WIND TURBINE BLADE AND A WIND TURBINE

Abstract

Provided is a wind turbine blade for a wind turbine, the wind turbine blade including a support element having first fibers being electrically conductive, and a fiber material having second fibers being electrically conductive, wherein the fiber material has a free portion and an overlapping portion which is at least partially attached and electrically connected to the support element, wherein an extension direction of the second fibers changes along an extension path of the second fibers, wherein a first angle is provided between the second fibers in the overlapping portion and the first fibers, wherein a second angle is provided between the second fibers in the free portion and the first fibers, and wherein the second angle is larger than the first angle.

Claims

1. A wind turbine blade for a wind turbine, the wind turbine blade comprising a support element having first fibers being electrically conductive, and a fiber material having second fibers being electrically conductive, wherein the fiber material has a free portion and an overlapping portion which is at least partially attached and electrically connected to the support element, wherein an extension direction of the second fibers changes along an extension path of the second fibers, wherein a first angle is provided between the second fibers in the overlapping portion and the first fibers, wherein a second angle is provided between the second fibers in the free portion and the first fibers, and wherein the second angle is larger than the first angle (1).

2. The wind turbine blade according to claim 1, wherein the first angle is between one of 0 and 50, 0 and 35, 0 and 20, 0 and 10, or 0.

3. The wind turbine blade according to claim 1, wherein the second angle between the first fibers and the second fibers is reduced continuously in the free portion towards the overlapping portion.

4. The wind turbine blade according to claim 1, wherein the second fibers are arc-shaped when looking perpendicularly on a broad side of the support element.

5. The wind turbine blade according to claim 1, wherein the fiber material comprises a weft thread extending wavelike along the extension direction of the second fibers for holding-together the second fibers.

6. The wind turbine blade according to claim 1, wherein at least one of the first fibers are unidirectional carbon fibers and the second fibers are unidirectional carbon fibers.

7. The wind turbine blade according to claim 1, wherein at least one of the support element is a spar cap comprising carbon fiber reinforced polymer material and the fiber material is a carbon fiber steered mat.

8. The wind turbine blade according to claim 1, further comprising an electrical conductor, wherein the fiber material has a further overlapping portion which is attached and electrically connected to the electrical conductor, wherein the second fibers extend from the further overlapping portion towards the overlapping portion.

9. The wind turbine blade according to claim 8, wherein the electrical conductor comprises an extension direction, and wherein an angle between the second fibers and the extension direction of the electrical conductor in the further overlapping portion is one of between 0 and 90, 30 and 90, 45 and 90, 60 and 90, 75 and 90, or 90.

10. The wind turbine blade according to claim 8, wherein the fiber material is warped or folded around the electrical conductor.

11. The wind turbine blade according to claim 8, further comprising a further electrical conductor and a further fiber material, wherein the further fiber material is attached and electrically connected to the support element and the further electrical conductor or the electrical conductor.

12. The wind turbine blade according to claim 11, wherein the electrical conductor and the fiber material are arranged at a blade root and wherein the further electrical conductor and the further fiber material are arranged at a blade tip.

13. The wind turbine blade according to claim 11, wherein the overlapping portion is sandwiched between the further fiber material and the support element.

14. The wind turbine blade according to claim 9, wherein at least one of the electrical conductor and the further electrical conductor is a metal cable.

15. A wind turbine comprising a wind turbine blade according to claim 1.

Description

BRIEF DESCRIPTION

[0047] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

[0048] FIG. 1 shows a perspective view of a wind turbine according to one embodiment;

[0049] FIG. 2 shows a perspective view of a wind turbine blade of the wind turbine according to FIG. 1;

[0050] FIG. 3 shows schematically a cross-sectional view from FIG. 2;

[0051] FIG. 4 shows schematically a perspective view of a fiber material;

[0052] FIG. 5 shows schematically a top view of a steered fiber material;

[0053] FIG. 6 shows schematically a top view of a connecting arrangement of the wind turbine blade according to FIG. 2;

[0054] FIG. 7 shows schematically a perspective view of a further embodiment of the connecting arrangement;

[0055] FIG. 8 shows schematically a cross-sectional view VIII-VIII from FIG. 7; and

[0056] FIG. 9 shows schematically a perspective view of a further embodiment of the connecting arrangement.

[0057] In the Figures, like reference numerals designate like or functionally equivalent elements, unless otherwise indicated.

DETAILED DESCRIPTION

[0058] FIG. 1 shows a wind turbine 1. The wind turbine 1 comprises a rotor 2 connected to a generator (not shown) arranged inside a nacelle 3. The nacelle 3 is arranged at an upper end of a tower 4 of the wind turbine 1.

[0059] The rotor 2 comprises three wind turbine blades 5. The wind turbine blades 5 are connected to a hub 6 of the wind turbine 1. Rotors 2 of this kind may have diameters ranging from, for example, 30 to 200 meters or even more. The wind turbine blades 5 are subjected to high wind loads. At the same time, the wind turbine blades 5 need to be lightweight. For these reasons, wind turbine blades 5 in modern wind turbines 1 are manufactured from fiber-reinforced composite materials. Oftentimes, glass or carbon fibers in the form of unidirectional fiber mats are used.

[0060] FIG. 2 shows a wind turbine blade 5. The wind turbine blade 5 comprises an aerodynamically designed portion 7 which is shaped for optimum exploitation of the wind energy and a blade root 8 for connecting the wind turbine blade 5 to the hub 6. Further, the wind turbine blade 5 comprises a blade tip 9, wherein the blade root 8 and the blade tip 9 face opposite sides. The wind turbine blade 5 extends in a longitudinal direction L. The blade 5 has a length M which, for example, may be between 15 to 125 m.

[0061] FIG. 3 shows schematically a cross-sectional view from FIG. 2. All elements shown in FIG. 3 are shown simplified. It is understood that intermediate elements, in particular further connecting elements, reinforcement elements and shells, may be provided.

[0062] The wind turbine blade 5 comprises an outer blade shell 10 comprising a first half-shell 11 and a second half-shell 12 which are connected together at one side 13 of the wind turbine blade 5, in particular at a trailing edge, and at the other side 14 of the wind turbine blade 5, in particular at a leading edge, to form the outer shell 10 of the wind turbine blade 5.

[0063] A chord line C intersects the trailing edge and the leading edge. The blade shell 10 may comprises composite fiber material. Further, the first half-shell 11 and the second half-shell 12 may be adhesively bonded together. Alternatively, the blade shell 10 may be provided as a one-piece element. The first half-shell 11 comprises an inner surface 15 and the second half-shell 12 comprises an inner surface 16 being opposite to each other, wherein an inner space 17 of the wind turbine blade 5 is defined by the inner surfaces 15, 16.

[0064] A web 18, in particular a shear web, is located inside the inner space 17 extending from the inner surface 15 of the first half-shell 11 to the inner surface 16 of the second half-shell 12. The wind turbine blade 5 further comprises a support element 19, in particular a first carbon fiber reinforced beam and/or spar cap, connected to the first half-shell 11 and a support element 20, in particular a second carbon beam and/or spar cap, connected to the second half-shell 12.

[0065] In particular, the support elements 19, 20 are electrically conductive and extend along the longitudinal direction L. The web 18 also extends along the longitudinal direction L.

[0066] The web 18 is located between the support element 19 and the support element 20, wherein the web 18 and the support elements 19, 20 are forming an I-shaped cross section. The web 18 and the support elements 19, 20 are forming a support structure preventing breaking or crippling of the wind turbine blade 5. Alternatively, or additionally, the support element 19, 20 may be provided near to the trailing edge or near to the leading edge of the wind turbine blade 5.

[0067] Further, a lightning conductor 21 is provided extending along the longitudinal direction L and being attached to the web 18. The lightning conductor 21 is arranged between the support elements 19, 20. The lightning conductor 21 is a down conductor. In particular, the lightning conductor 21 is a metal cable. Further, the lightning conductor 21 is grounded.

[0068] Further, an electrical conductor 22 extending in the longitudinal direction L is provided inside the inner space 17. The electrical conductor 22 is connected to the inner surface 15. In particular, a receptor 23 (lighting rod or air terminal) is arranged at an outer surface 24 of the blade 5. The receptor 23 is directly or indirectly electrically connected to the electrical conductor 22 and the lightning conductor 21 (connection not shown). The electrical conductor 22 is directly connected and/or connected by means of a further cable to the lighting conductor 21 (not shown).

[0069] A plurality of receptors 23 may be provided at the outer surface 24. The receptors 23 and the conductor 21 form a lightning protection system. Further, a fiber material 25 being electrically conductive is provided. The fiber material 25 is attached and, thus, directly electrically connected to the electrical conductor 22.

[0070] The electrical conductor 22 is a metal (e.g. copper or aluminum) cable. Furthermore, the fiber material 25 is attached and, thus, directly electrically connected to the support element 19.

[0071] FIG. 4 shows schematically a perspective view of the fiber material 25. The fiber material 25 comprises a plurality of fibers 27 (also referred as second fibers). In particular, the fibers 27 are unidirectional and, in particular, continuous carbon fibers. The fibers 27 are embedded in a matrix 28, for example plastic material, in particular resin. The fibers 27 extend parallel to a direction Z which is perpendicular to a direction X and a direction Y. Further, the fibers 27 run straight. Each fiber 27 may be a single fiber or a fiber bundle. A thickness T of the fiber material 25 extends in the direction Y. A width W of the fiber material 25 extends in the direction X.

[0072] An electrical conductivity matrix .sub.CFC of such a fiber material 25 is in particular:

[00001]${}_{\mathrm{CFC}}=\left(\begin{array}{ccc}88& 0& 0\\ 0& 15& 0\\ 0& 0& 24000\end{array}\right).Math..Math.S.Math.\text{/}.Math.m$

[0073] The electrical conductivity is indicated in Siemens (S) per Meter (m). As shown above the conductivity in the direction Z which is the extension direction of the carbon fibers 27 is many times larger than the conductivities in the direction X and the direction Y. This illustrates an anisotropy of the fiber material 25. The fibers 27 are the main reason for a sufficient electrical conductivity of the fiber material 25. The conductivity in the direction Z is between 20000 and 30000 S/m.

[0074] FIG. 5 shows schematically a top view of the fiber material 25 whichin this embodimentis provided as a steered fiber material. In particular, this means that the fibers 27 are curved having a curve radius R, in particular between 100 and 1000 mm.

[0075] The fibers 27 are, for example, warp threads. The fiber material 25 further comprises at least one weft thread 29 extending wavelike along the curved shape of the fibers 27 for holding-together or bundle the fibers 27. The weft threads 29 are threaded perpendicularly through the fibers 27. The at least one weft thread 29 comprises glass fibers or is a glass fiber bundle. Alternatively, the at least one weft thread 29 comprises carbon fibers or is a carbon fiber bundle. In particular, the weft thread 29 is electrically conductive.

[0076] The weft threads 29 are also provided in the fiber material shown in FIG. 4. Therefore, the electrical conductivity in the direction X is greater than in the direction Y (see FIG. 4). A plurality 30 of fibers 27 is arranged side by side forming a curved main extension direction V of the fiber material 25. By curving the plurality 30 of fibers 27, a curved path having sufficient electrical conductivity along the curved path can be provided. The fibers 27 are curved and are the main reason for a sufficient electrical conductivity. The conductivity in the direction V of the fiber material 25 is between 20000 and 30000 S/m.

[0077] FIG. 6 shows schematically a top view of a connecting arrangement 26 of the wind turbine blade 5 according to FIG. 2. The connecting arrangement 26 comprises the support element 19 having fibers 31 (also referred as first fibers) being electrically conductive, and the fiber material 25 having the fibers 27 being electrically conductive. The fiber material 25 is attached and electrically connected to the support element 19 forming an overlapping portion 32. The fibers 27 extend towards the support element 19 and the extension direction V of the fibers 27 is adjustedwhen looking from a top view and/or when looking perpendicularly on a broad side 33 of the support element 19such that an electrical conductivity discontinuity through the overlapping portion 32 is reduced.

[0078] In particular, the extension direction V of the fibers 27 changes such that an angle 1 (also referred as first angle) between the fibers 31 in the overlapping portion 32 and the fibers 27 is reduced. For example, the angle 1 in the overlapping portion 32 is between 0 and 50, 0 and 35, 0 and 20 or 0 and 10, in particular 0. This means that the angle 1 between the fibers 31 and the fibers 27 is reduced along an extension path 52 of the fibers 27 towards the support element 19. The angle 1 decreases, in particular continuously, along the extension direction V towards an end 34 of the fiber material 25 which overlaps with the support element 19. Alternatively, the fibers 27 may be kinked having a distinct kink (not shown).

[0079] Further, the fiber material 25 has a free portion 53 which is directly connected to the overlapping portion 32. The extension direction V of the second fibers 27 changes along the extension path 52 of the second fibers 27. An angle 2 (also referred as second angle is provided between the second fibers 27 in the free portion 53 and the first fibers 31. The angle 2 is larger than the angle 1.

[0080] The arrangement 26 further comprises an electrical conductor 35, wherein the fiber material 25 is attached and electrically connected to the electrical conductor 35 forming a further overlapping portion 36 which is directly connected to the free portion 53. The free portion 36, the overlapping portion 32 and the further overlapping portion 36 are one-piece. The fibers 27 extend from the further overlapping portion 36 to the overlapping portion 32.

[0081] For example, the electrical conductor 35 may be the electrical conductor 22 from FIG. 3. The fibers 27 extend from the further overlapping portion 36 towards the overlapping portion 32. As shown in FIG. 6, the overlapping portion 32 overlaps with the support element 19 and the further overlapping portion 36 overlaps with the electrical conductor 35. In particular, the electrical conductor 35 is a metal cable. For example, the angle 2 is reduced continuously from the further overlapping portion 36 towards the overlapping portion 32.

[0082] In particular, the second fibers 27 and the fiber material 25 are arc-shaped when looking perpendicularly on the broad side 33 of the support element 19. The fibers 27 are single-curved. The electrical conductor 35 comprises an extension direction E. An angle between the fibers 27 and the extension direction E of the electrical conductor 35 in the further overlapping portion 36 is between 0 and 90, 30 and 90, 45 and 90, 60 and 90, or 75 and 90, in particular 90. In particular, the fibers 31 are unidirectional carbon fibers and the fibers 27 are unidirectional carbon fibers.

[0083] The fibers 31 and the fibers 27 are of an identical type having the same electrical conductivity. This has the advantage that the impedance of the support element 19 and the fiber material 25 is in the same range and thus current is transferred homogenous, i.e. not mainly at the edges of the connection, from the fiber material 25 to the carbon element 19. The fiber material 25 and the support element 19 are made from the same material.

[0084] FIG. 7 shows schematically a perspective view of a further embodiment of the connecting arrangement 26. The support element 19 is a spar cap comprising carbon fiber reinforced polymer material (CFRP).

[0085] In contrast to FIG. 6 the arrangement 26 comprises an electrical conductor 37 (also referred as further electrical conductor) and a fiber material 38 (also referred as further fiber material), wherein the fiber material 38 is attached and electrically connected to the support element 19 and the electrical conductor 37. The electrical conductor 35 and the fiber material 25 are arranged near to the blade root 8 (see FIG. 2) and the electrical conductor 37 and the fiber material 38 are arranged near to the blade tip 9 (see FIG. 2).

[0086] The fiber material 38 is mirror symmetrically arranged regarding fiber material 25. An end portion 40 of the support element 19 is wedge-shaped. The overlapping portion 32 is provided at the end portion 40. In particular, another end portion 41 of the support element 19 is also wedge-shaped. The fiber material 38 is connected to the other end portion 41.

[0087] Moreover, an electrical conductor 39 and a fiber material 42 are provided. The fiber material 42 is attached and electrically connected to the support element 19 and the electrical conductor 39. The electrical conductor 39 and the fiber material 42 are provided as mid connection arranged between the fiber material 25 and the fiber material 38. The electrical conductor 35, the electrical conductor 37 and the electrical conductor 39 may be provided as a one-piece conductor, in particular a LPS-cable and/or the conductor 22 (see FIG. 3). Alternatively, the conductors 35, 37, 39 may be provided as separate conductors, in particular LPS-cables.

[0088] The fiber materials 38, 42 may be connected to the support element 19 as described for fiber material 25. The broad side 33 may be provided as broadest side of the support element 19. The support element 19 further comprises a narrow side 43, wherein the broad side 33 is several times larger than the narrow side. Thus, the support element 19 is provided as a flat element. The support element 19 has a rectangular cross-sectional shape.

[0089] Optionally, a core insert 44 may be provided which is attached to the narrow side 43. The electrical conductor 39 is arranged in a plane P which is provided parallel and offset to the broad side 33. In particular, the core insert 44 provides a rounded transition between broad side 33 and the plane P.

[0090] The core insert 44 is provided over the complete length of the support element 19. The electrical conductors 37, 39 are connected to the fiber materials 38, 42 as described for the electrical conductor 35 and the fiber material 25. In particular, the support element 19 has a conductivity between 20000 and 30000 S/m, in particular 24000 S/m, in longitudinal direction L.

[0091] FIG. 8 shows schematically cross-sectional view VIII-VIII from FIG. 7 which shows a connection 45 between the electrical conductor 39 and the fiber material 42, in particular the further overlapping portion 36. The fiber material 42 is warped or folded around the electrical conductor 39. The fiber material 42 encompasses the electrical conductor 39, wherein an end portion 46 of the fiber material 42 overlaps with an intermediate portion 47 of the fiber material 42 which extend towards the electrical conductor 39.

[0092] Alternatively, the fiber material 42 may be warped around the electrical conductor 39 without forming an overlapping portion.

[0093] FIG. 9 shows schematically a further embodiment of the connecting arrangement 26. In contrast to FIG. 7, the electrical conductor 35 is electrically connected to the support element 19 by means of two fiber materials 25, 48 having different radii R. Therefore, a redundant connection between the electrical conductor 35 and the support element 19, in particular the end portion 40 may be provided.

[0094] The fiber material 48 comprises fibers 49 which are provided as described for fibers 27. The fiber material 48 is attached and electrically connected to the overlapping portion 32 by means of an overlapping portion 50 which overlaps with the overlapping portion 32. In particular, the fiber material 48 is also attached to the support element 19.

[0095] Further, the fiber material 48 is attached and electrically connected to the electrical conductor 35 forming an overlapping portion 51. The overlapping portion 32 is sandwiched between the support element 19, in particular the end portion 40, and the fiber material 48, in particular the overlapping portion 50. The overlapping portion 51 is provided as described for overlapping portion 36. The overlapping portions 36, 51 are provided side by side along the direction E.

[0096] For example, every fiber material 25, 38, 27 shown in FIG. 7 may be substituted by two fiber materials 25, 48 as shown in FIG. 9. Alternatively, all fiber materials 25, 38, 27 shown in FIG. 7 may be substituted by merely two fiber materials 25, 48 as shown in FIG. 9.

[0097] The fiber materials 25, 38, 42, 48 may be provided as described regarding FIGS. 5, 6 and/or 9. The connection portions 36, 51 between the conductors 35, 37, 39 and the fiber materials 25, 38, 42, 48 may be provided as described regarding FIG. 8. The electrical conductivities explained with regard to FIG. 4 apply mutatis mutandis to all fiber materials 25, 38, 42, 48.

[0098] Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

[0099] For the sake of clarity, it is to be understood that the use of a or an throughout this application does not exclude a plurality, and comprising does not exclude other steps or elements.