Abstract
The invention relates to a wind turbine blade for a wind turbine, having a tip end area, a tip end and a root end area and a lightning protection system. The lightning protection system comprises at least one metal foil, wherein said metal foil extends continuously from a first end in the tip end area towards the root end area of the blade and wherein the metal foil is arranged in proximity to the outer surface of the blade, so that the metal foil is adapted to function as a receptor of a stroke of lightning and as a down conductor. The lightning protection system further comprises a first metallic lightning receptor being in direct electrical contact with the metal foil, wherein the first metallic lightning receptor is disposed in proximity to the outer surface of the blade and between the first end of the metal foil and the blade tip end.
Claims
1. A wind turbine blade for a wind turbine, having a tip end area, a root end area, a tip end, and a lightning protection system, wherein said tip end is disposed in the tip end area, and said lightning protection system comprising at least one metal foil, wherein a first end of the metal foil is disposed in the tip end area of the blade, wherein the metal foil extends from said first end towards the root end area of the blade, and wherein the metal foil is arranged in proximity to the outer surface of the blade, so that the metal foil is adapted to function as a receptor of a stroke of lightning and as a down conductor, said lightning protection system further comprising a first metallic lightning receptor, wherein the first metallic lightning receptor is disposed between the first end of the metal foil and the tip end of the blade, wherein the first metallic lightning receptor is in direct electrical contact with the metal foil, and wherein the first metallic lightning receptor is arranged in proximity to the outer surface of the blade.
2. The wind turbine blade according to claim 1, wherein the first metallic lightning receptor is flat-shaped or bar-shaped.
3. The wind turbine blade according to claim 1, wherein the first metallic lightning receptor comprises a metallic plate.
4. The wind turbine blade according to claim 1, wherein the first metallic lightning receptor tapers towards the tip end of the blade.
5. The wind turbine blade according to claim 1, wherein the first metallic lightning receptor extends over substantially the entire blade surface in the tip end area.
6. The wind turbine blade according to claim 1, wherein the first metallic lightning receptor comprises a solid metallic member
7. The wind turbine blade according to claim 1, wherein the first metallic lightning receptor extends continuously from the first end of the metal foil to the blade tip end.
8. The wind turbine blade according to claim 1, wherein part of the first metallic lightning receptor is arranged overlapping with the metal foil, so that an overlap section between the metal foil and the first metallic lightning receptor is formed.
9. The wind turbine blade according to claim 8, wherein the first metallic lightning receptor and the metal foil are clamped between two metal plates in the overlap section.
10. The wind turbine blade according to claim 1, wherein the first metallic lightning receptor and the metal foil are connected by means of clamping, caulking or by means of a bonding agent.
11. The wind turbine blade according to claim 1, wherein the lightning protection system comprises at least one disk receptor, said disk receptor being disposed in proximity to the first end of the metal foil.
12. The wind turbine blade according to claim 1, wherein the first metallic lightning receptor comprises copper.
13. The wind turbine blade according to claim 1, wherein the first metallic lightning receptor is covered only by a thin protective layer in the radial outer direction of the blade.
14. The wind turbine blade according to claim 1, wherein the lightning protection system comprises a second metallic lightning receptor, wherein said second metallic lightning receptor is disposed at the tip end of the blade, and wherein said second metallic lightning receptor is in direct electrical contact with the first metallic lightning receptor.
15. The wind turbine blade according to claim 14, wherein the second metallic lightning receptor comprises a rod receptor.
16. The wind turbine blade according to claim 15, wherein the rod receptor comprises a base plate, wherein said base plate is located inside the blade, and wherein at least one disk receptor is mounted on the base plate.
17. The wind turbine blade according to claim 14, wherein the second metallic lightning receptor comprises a solid metallic blade tip.
18. The wind turbine blade according to claim 17, wherein the solid metallic blade tip comprises connection means for connecting to the first metallic lightning receptor.
19. The wind turbine blade according to claim 14, wherein the first metallic lightning receptor is connected to the second metallic lightning receptor by means of clamping, caulking or by means of a bonding agent.
20. The wind turbine blade according to claim 14, wherein the second metallic lightning receptor comprises copper.
Description
BRIEF DESCRIPTION OF DRAWINGS
[0044] The invention will be described below with reference to the following figures which show in schematic representation
[0045] FIG. 1 is a top view of a section of a wind turbine blade with a lightning protection system;
[0046] FIG. 2 is a cross sectional view of the section of the blade of FIG. 1 in its tip end area;
[0047] FIG. 3 is a longitudinal sectional view of the section of the blade of FIG. 1 in its tip end area;
[0048] FIG. 4 is a longitudinal sectional view of the section of the blade of FIG. 1 along the cutting line A-A;
[0049] FIG. 5 is a top view of a section of a wind turbine blade with a lightning protection system;
[0050] FIG. 6 is a cross sectional view of the section of the blade of FIG. 5 in its tip end area;
[0051] FIG. 7 is a longitudinal sectional view of the section of the blade of FIG. 5 in its tip end area;
[0052] FIG. 8 is a longitudinal sectional view of the section of the blade of FIG. 5 along the cutting line A-A;
[0053] FIG. 9 is a top view of a section of a wind turbine blade with a lightning protection system;
[0054] FIG. 10 is a cross sectional view of the section of the blade of FIG. 9 in its tip end area;
[0055] FIG. 11 is a longitudinal sectional view of the section of the blade of FIG. 9 in its tip end area;
[0056] FIG. 12 is a longitudinal sectional view of the section of the blade of FIG. 9 along the cutting line A-A;
[0057] FIG. 13 is a top view of a section of a wind turbine blade with a lightning protection system;
[0058] FIG. 14 is a cross sectional view of the section of the blade of FIG. 13 in its tip end area;
[0059] FIG. 15 is a longitudinal sectional view of the section of the blade of FIG. 13 in its tip end area;
[0060] FIG. 16 is a longitudinal sectional view of the section of the blade of FIG. 13 along the cutting line A-A;
[0061] FIG. 17 is a top view of a section of a wind turbine blade with a lightning protection system;
[0062] FIG. 18 is a cross sectional view of the section of the blade of FIG. 17 in its tip end area;
[0063] FIG. 19 is a longitudinal sectional view of the section of the blade of FIG. 17 in its tip end area; and
[0064] FIG. 20 is a longitudinal sectional view of the section of the blade of FIG. 17 along the cutting line A-A.
DESCRIPTION OF EMBODIMENTS
[0065] FIG. 1 shows a top view of a section of a wind turbine blade 10 comprising a tip end area 11 and a tip end 12, wherein the tip end 12 is disposed in the tip end area 11. The wind turbine blade 10 further has a lightning protection system comprising two metal foils 13, 14 formed as strips out of copper which both have a first end 13a, 14a disposed in the tip end area 11 of the blade 10. The metal foils 13, 14 extend from their first ends 13a, 14a along the longitudinal direction of the blade 10 towards its root end.
[0066] The blade 10 further comprises an outer blade layer 25 (see FIGS. 2 and 3) of which in FIG. 1 only the outline is shown. The metal foils 13, 14 are arranged in radial direction behind spar caps 26a, 26b which are located underneath the outer blade layer 25. Since the spar caps 26a, 26b are disposed underneath the outer blade layer and the metal foils 13, 14, the spar caps 26a, 26b are shown by broken lines. The spar caps 26a, 26b extend from the root end of the blade 10 towards the tip end 12 of the blade along a substantial part of the length of the blade. However, the spar caps 26a, 26b are not disposed at the tip end area 11 of the blade 10.
[0067] The metal foils 13, 14 are arranged substantially parallel to the longitudinal direction of the blade 10. For the section of the blade 10 shown in FIG. 1 the metal foils 13, 14 overlap with each other. When extending towards the root end of the blade 10 the metal foils increasingly diverge from each other until they are not arranged overlapping anymore for the substantial part of the length of the blade 10.
[0068] The lightning protection system further comprises a first metallic lightning receptor 17. The first metallic lightning receptor 17 being a metallic plate out of copper is disposed between the first ends 13a, 14a of the metal foils 13, 14 and the tip end 12 of the blade 10. The first metallic lightning receptor 17 extends continuously from a first end 17a to the blade tip end 12 of the blade 10. The first end 17a of the first metallic lightning receptor 17 is arranged towards the root end of the blade 10 as seen from the first ends 13a, 14a of the metal foils 13, 14. The first metallic lightning receptor 17 extends over the entire blade surface in the tip end area 11 of the blade 10.
[0069] The lightning protection system further comprises two disk receptor pairs of which two disk receptors 18, 19 are shown in FIG. 1. The disk receptors 18, 19 are disposed in proximity to the first ends 13a, 14a of the metal foils 13, 14. The disk receptors 18, 19 comprise a base plate 21a which is disposed in outer radial direction behind the first metallic lightning receptor 17. The disk receptors 18, 19 are embedded inside the blade 10 and are mounted on the base plate 21a. The disk receptors 18, 19 protrude out of the outer blade layer 25 to the outside of the blade 10. The metal foils 13, 14 have approximately the same width as the base plate 21a.
[0070] FIG. 2 shows a cross sectional view of the section of the blade of FIG. 1 in its tip end area 11. The outer blade layer 25 representing the outermost layer of the blade 10 is shown by a thick line. The outer blade layer 25 covering the first metallic lightning receptor is only a thin protective layer. The first metallic lightning receptor 17 extends over the entire blade surface in the blade tip end area 11 adapting to the shape of the blade surface. The first metallic lightning receptor 17 is arranged adjoining the inside of the outer blade layer 25 in the blade tip end area 11 except for overlap sections 23a, 23b (see FIG. 4) with the metal foils 13, 14. Since only the outer blade layer 25 separates the first metallic lightning receptor 17 from the outside of the blade 10 in radial outer direction, the receptive properties of the first metallic lightning receptor 17 are only slightly decreased and the first metallic lightning receptor 17 can function as a direct lightning receptor.
[0071] The adjoining arrangement can also be seen in FIG. 3 which shows a longitudinal sectional view of the section of the blade 10 of FIG. 1 in its tip end 12. The first metallic lightning receptor 17 extends all the way to the tip end 12 of the blade 10.
[0072] FIG. 4 shows a longitudinal sectional view of the section of the blade 10 of FIG. 1 along the cutting line A-A. On the other side of the blade 10 which is not shown in FIG. 1 two more metal foils 15, 16 are arranged so that the entire blade 10 comprises two metal foils on each side and therefore four metal foils 13, 14, 15, 16 are shown by broken lines in FIG. 4. Furthermore, the blade 10 comprises four spar caps of which two spar caps 26a, 26c, one on each side of the blade 10, are shown in FIG. 4. On both sides the metal foils 13, 14, 15, 16 extend from their first ends 13a, 14a, 15a, 16a disposed in the tip end area 11 of the blade 10 towards the root end area of the blade 10. For the length of the spar caps 26a, 26c the metal foils 13, 14, 15, 16 are disposed in radial direction behind the spar caps 26a, 26c and therefore between the spar caps 26a, 26c and the radial outer blade layer 25 which can only be a thin protective layer.
[0073] In FIG. 4 two disk receptors 18, 20 of the two disk receptor pairs are shown which are mounted on a base plate 21a, 21b respectively. The disk receptors 18, 20 being disposed on opposite sides of the blade 10 are connected by a bolt 22 serving as an attachment as well as an electrical connection. The two metal foils of each side 13, 14 and 15, 16 are arranged at the inside of one of the base plate 21a, 21b respectively. Therefore, the metal foils 13, 14 are arranged overlapping with the base plate 21a, and the metal foils 15, 16 are arranged overlapping with base plate 21b.
[0074] The first metallic lightning receptor 17 extending over the entire surface of the blade 10 in its tip end area 11 has a first end 17a at each side of the blade 10. At the one side of the blade 10, the first metallic lightning receptor 17 is arranged at the inside of the metal foils 13, 14 whereas at the opposing side the first metallic lightning receptor 17 is arranged at the inside of the metal foils 15, 16. Even though between the metal foil 13, 16 and the first metallic lightning receptor 17 another metal foil 14, 15 is disposed, the first metallic lightning receptor and the metal foils 14, 15 are nonetheless considered to be in direct electrical contact. In this way, overlap sections 23a, 23b between the first metallic lightning receptor 17 and at least one of the metal foils 13, 14, 15, 16 are created. This results in a very large direct electrical contact area between the first metallic lightning receptor 17 and at least one of the metal foils 13, 14, 15, 16 on each side. For connection purposes there is another metal plate 24a, 24b on each side of the blade 10 which clamps the first metallic lightning receptor 17 and the metal foils 13, 14, 15, 16 in their overlap section 23a, 23b. Therefore, the first metallic lightning receptor 17 is arranged between the base plates 21a, 21b and the metal plates 24a, 24b in the overlap section 23a, 23b. Outside of the overlap section 23a, 23b the first metallic lightning receptor 17 is disposed at the inside of the outer blade layer 25. The metal plates 23a, 23b, the base plates 21a, 21b, the metal foils 13, 14, 15, 16 and the first metallic lightning receptor 17 are made out of copper.
[0075] FIG. 5 shows a top view of a section of another wind turbine blade 10 with a tip end 12, a tip end area 11 and a lightning protection system. The metal foils 13, 14, the outer blade layer 25 and the spar caps 26a, 26b are arranged in the same way as in FIG. 1.
[0076] The first metallic lightning receptor 17 in FIG. 5 is a metallic plate being disposed between the first ends 13a, 14a of the metal foils 13, 14 and the tip end 12 of the blade 10 and extending continuously from a first end 17a to the blade tip 12 of the blade 10. Furthermore, the first metallic lightning receptor 17 extends over the entire blade surface in the tip end area 11. The first end 17a of the first metallic lightning receptor 17 is arranged between the first end 13a, 14a of the metal foils 13, 14 and the root end of the blade 10 but in proximity to the first ends 13a, 14a of the metal foils 13, 14.
[0077] In FIG. 6 a cross sectional view of the section of the blade of FIG. 5 in its tip end area 11 is shown. The first metallic lightning receptor 17 and the outer blade layer 25 are arranged in the same way as in FIG. 2.
[0078] FIG. 7 shows a longitudinal sectional view of the section of the blade 10 of FIG. 5 in its tip end area 11. The first metallic lightning receptor 17 and the outer blade layer 25 are arranged in the same way as in FIG. 3.
[0079] FIG. 8 shows a longitudinal sectional view of the section of the blade 10 of FIG. 5 along the cutting line A-A. The arrangement of the outer blade layer 25 and the spar caps 26a, 26b is the same as in FIG. 4. The metal foils 13, 14, 15, 16 are disposed at the inside of the outer blade layer 25 along their complete length. The first metallic lightning receptor 17 extends from the blade tip 12 beyond the first ends 13a, 14a, 15a, 16a of the metal foils 13, 14, 15, 16 towards the root end of the blade 10 until its first end 17a. The first metallic lightning receptor 17 is arranged at the inside of the outer blade layer 25 at the tip end area 11 of the blade except for overlap sections 23a, 23b at which the first metallic lightning receptor 17 is arranged adjoining the inside of at least one of the metal foils 13, 14, 15, 16 on each blade side. The first metallic lightning receptor 17 and the metal foils 13, 14, 15, 16 are connected by means of a bonding agent.
[0080] FIG. 9 shows a top view of a section of another wind turbine blade 10 with a tip end 12, a tip end area 11 and a lightning protection system. The first metallic lightning receptor 17, metal foils 13, 14, the outer blade layer 25 and the spar caps 26a, 26b are arranged in the same way as in FIG. 5. The only difference is that in FIG. 9 the first metallic lightning receptor 17 is a solid metallic member out of copper. Since the first metallic lightning receptor 17 is solid the entire volume inside of the blade 10 in its tip end area 11 is occupied with the first metallic lightning receptor 17.
[0081] In FIG. 10 a cross sectional view of the section of the blade of FIG. 9 in its tip end area 11 is shown. The first metallic lightning receptor 17 adapts to the shape of the blade surface being arranged adjoining the inside of the outer blade layer 25 in the tip end area 11 of the blade 10 except for overlap sections 23a, 23b with the metal foils 13, 14, 15, 16 (see FIG. 12).
[0082] FIG. 11 shows a longitudinal sectional view of the section of the blade 10 of FIG. 9 in its tip end area 11. The first metallic lightning receptor 17 extends to the tip end 12 of the blade 10 occupying the entire volume inside of the blade 10 in its tip end area 11.
[0083] FIG. 12 shows a longitudinal sectional view of the section of the blade 10 of FIG. 9 along the cutting line A-A. The arrangement of the outer blade layer 25 and the spar caps 26a, 26b is the same as in FIG. 4. The metal foils 13, 14, 15, 16 are disposed at the inside of the outer blade layer 25 along their complete length. The first metallic lightning receptor 17 extends from the blade tip 12 beyond the first ends 13a, 14a, 15a, 16a of the metal foils 13, 14, 15, 16 towards the root end of the blade 10 until its first end 17a. The first metallic lightning receptor 17 is arranged at the inside of the outer blade layer 25 at the tip end area 11 of the blade except for overlap sections 23a, 23b at which the first metallic lightning receptor 17 is arranged adjoining the inside of at least one of the metal foils 13, 14, 15, 16 on each blade side. The first metallic lightning receptor 17 and the metal foils 13, 14, 15, 16 are connected by means of a bonding agent.
[0084] In FIG. 13 a top view of a section of another wind turbine blade 10 with a tip end 12, a tip end area 11 and a lightning protection system is shown. The metal foils 13, 14, the outer blade layer 25 and the spar caps 26a, 26b are arranged in the same way as in FIG. 1. The first metallic lightning receptor 17 in FIG. 13 is a metallic plate out of copper being disposed between the first ends 13a, 14a of the metal foils 13, 14 and the tip end 12 of the blade 10.
[0085] The lightning protection system further comprises a second metallic lightning receptor 27 at the tip end 12 of the blade 10. The second metallic lightning receptor 27 comprises a rod receptor 28 which is mounted on a base plate 29 inside of the blade 10 (see FIGS. 14, 15 and 16). The first metallic lightning receptor 17 extends continuously from a first end 17a (see FIG. 16) to the second metallic lightning receptor 27. Starting from its first end 17a towards the second metallic lightning receptor 27 the width of the first metallic lightning receptor 17 tapers so that its width 17b at the second metallic lightning receptor 27 is smaller than its width 17c at its first end 17a.
[0086] The second metallic lightning receptor 27 further comprises two disk receptors 30, 31 being mounted on the base plate 29 of the rod receptor 28 of which one disk receptor 30 protruding through the first metallic lightning receptor 17 and the outer blade layer 25 can be seen in FIG. 13. The first metallic lightning receptor 17 extends beyond the base plate 29 (see FIGS. 14, 15 and 16) of the second metallic lightning receptor 27 but does not extend all the way to the tip end 12 of the blade 10.
[0087] In FIG. 14 a cross sectional view of the section of the blade 10 of FIG. 13 in its tip end area 11 is shown. Apart from the rod receptor 28 the two disk receptors 30, 31 are mounted on the base plate 29 of the rod receptor 28. The first metallic lightning receptor 17 adapts to the shape of the blade surface. The first metallic lightning receptor 17 is in direct electrical contact with the disk receptors 30, 31 and therefore in direct electrical contact with the second metallic lightning receptor 27.
[0088] FIG. 15 shows a longitudinal sectional view of the section of the blade 10 of FIG. 13 in its tip end area 11. The first metallic lightning receptor 17 extends beyond the base plate 29 of the rod receptor 28 but not all the way to the tip end 12 of the blade 10. The rod receptor 28 protrudes through the outer blade layer 25 at the tip end 12 of the blade 10.
[0089] FIG. 16 shows a longitudinal sectional view of the section of the blade 10 of FIG. 13 along the cutting line A-A. The arrangement of the first metallic lightning receptor 17, the metal foils 13, 14, 15, 16, the spar caps 26a, 26b and the outer blade layer 25 is the same as in FIG. 4.
[0090] FIG. 17 shows a top view of a section of another wind turbine blade 10 with a tip end 12, a tip end area 11 and a lightning protection system. The metal foils 13, 14 and the spar caps 26a, 26b are arranged in the same way as in FIG. 1.
[0091] The first metallic lightning receptor 17 in the form of a metallic plate extends continuously and in a tapering way from its first end 17a to a second metallic lightning receptor 27. The width 17b of the first metallic lightning receptor 17 at the second metallic lightning receptor 27 is smaller than its width 17b at its first end 17a. The second metallic lightning receptor 27 comprises a solid metal blade tip 32. At the radial outside of the solid metal blade tip 32, there may be an outer blade layer 25 in form of a protective coating or no outer blade layer at all.
[0092] In FIG. 18 a cross sectional view of the section of the blade of FIG. 17 in its tip end area 11 is shown. The first metallic lightning receptor 17 adapts to the shape of the blade surface and is arranged at the inside of the outer blade layer 25 along its complete width.
[0093] In FIG. 19 a longitudinal sectional view of the section of the blade 10 of FIG. 17 in its tip end area 11 is shown. The first metallic lightning receptor 17 is in direct electrical contact to the second metallic lightning receptor 27 in the form of the solid metallic blade tip 32 by means of connections means in the form of connection webs 33a, 33b.
[0094] FIG. 20 shows a longitudinal sectional view of the section of the blade 10 of FIG. 17 along the cutting line A-A. The arrangement of the first metallic lightning receptor 17, the metal foils 13, 14, 15, 16, the spar caps 26a, 26b and the outer blade layer 25 is the same as in FIG. 4.
