Blade for a wind turbine and method for manufacturing a blade

Abstract

A blade for a wind turbine, comprising a heating device (21) connected to power cables (40, 41), a lightning protection system (30) comprising a down conductor (31), and a surge protection device (33). The heating device (21) comprises a first radiating element (22) and a second radiating element (26) arranged adjacent to each other around the leading edge (7) of the blade (1), the first radiating element (22) being connected to the power cables (30, 31) at respective connection points (C1, C2) via respective electrical connectors (34a, 34b), and the down conductor (31) being connected to each power cable (30, 31) at the connection points (C1, C2) via respective surge protection devices (33), the second radiating element (26) being connected to the first radiating element (22) such that the second radiating element (26) is powered only via the first radiating element (22). A method for manufacturing a blade.

Description

Technical Field

[0001] The present invention relates to a blade for a wind turbine and a method for manufacturing a blade, in particular to a blade comprising an anti-icing system and a lightning protection system. Background Art

[0002] Wind turbine blades equipped with anti-icing and lightning protection systems are known in the art. Given the high likelihood of lightning strikes on wind turbines, and in particular on the blades of such turbines, it is necessary to equip the blades with lightning protection systems to minimize the effects of lightning on the blades, in particular on the blades and / or electrical components included in the wind turbine.

[0003] On the other hand, blades are known which comprise electrically conductive metal sheets in the outer laminate of the blade, in particular in the leading edge region, for preventing the formation of ice which adversely affects the efficiency of the wind turbine.

[0004] The presence of an anti-icing system in a blade can also affect the efficiency of the lightning protection system. To avoid this problem, EP2857678A1 describes a protection system that disables the heating mode and activates the lightning protection mode whenever a lightning strike is detected. This protection system includes at least one surge protection device that directly connects the electrodes connected to the conductive sheets of the anti-icing system to the lightning protection system's downconductor cable.

[0005] WO 2018 / 095649A1 describes a blade including a lightning protection system having a downconductor cable for conducting a lightning current received by a receiver to a ground terminal, and a conductive layer arranged on the outer surface of the blade shell, the downconductor cable and the conductive layer being electrically connected by a connecting surge device so that their potentials are equalized. Summary of the Invention

[0006] It is an object of the present invention to provide a blade for a wind turbine and a method for manufacturing a blade as defined in the claims.

[0007] Aspects of the present invention relate to a blade for a wind turbine, comprising an anti-icing system, a lightning protection system, and a surge protection device connecting the anti-icing system to the lightning protection system to ensure equal potential between the two systems. The anti-icing system includes a heating device connected to a power supply cable, and the lightning protection system includes at least one lightning down conductor and is configured to conduct lightning that strikes the blade to ground via the lightning down conductor.

[0008] The heating device comprises at least one first radiating element and at least one second radiating element, arranged facing each other around the leading edge of the blade. The first radiating element is connected to a power supply cable at a corresponding connection point via a corresponding electrical connector. A lightning conductor is connected to each power supply cable at a connection point via a corresponding surge protection device. The second radiating element is electrically connected to the first radiating element, so that the second radiating element is powered only by the first radiating element. Thus, the anti-icing system and the lightning protection system are electrically equalized by the electrical connection between the first and second radiating elements. Once the first and second radiating elements are electrically connected, not only is the second radiating element powered, but the entire lightning protection system of the blade remains connected and equalized relative to the anti-icing system.

[0009] The result is a blade with two independent circuits, one for lightning protection and one for anti-icing. Each housing contains an independent circuit, and the two circuits are connected by connecting the second radiating element to the first. This minimizes and optimizes the electrical connections.

[0010] Another aspect of the present invention relates to a method for manufacturing a blade having the aforementioned characteristics. The method comprises the following steps:

[0011] - depositing in a first mold a plurality of fabric layers or sheets that will form the lower shell of the blade, at least one first radiating element in the region of the leading edge of the first mold, and at least one connecting element in contact with the cavity of the first mold and with one electrical terminal of the first radiating element, the connecting element being configured to define in the lower shell a contact surface situated above the first radiating element, in particular above the electrical terminal of the first radiating element,

[0012] - Moulding the lower housing,

[0013] - connecting the first electrical terminal of the first radiating element to the first power supply cable, connecting the second electrical terminal of the first radiating element to the second power supply cable, and connecting the lightning down conductor to each power supply cable via a respective surge protection device,

[0014] - depositing in a second mould a plurality of fabric layers or sheets that will form the upper shell of the blade, comprising at least one second radiating element situated in the leading edge region of the second mould and at least one connecting element in contact with the cavity of the second mould and with the terminals of the second radiating element, said connecting element being configured to define in the upper shell a contact surface situated above the second radiating element, in particular above the electrical terminals of the second radiating element,

[0015] - closing the two molds against each other, wherein the connecting elements of the first mold and the connecting elements of the second mold face each other and sealing the upper shell and the lower shell to each other,

[0016] - removing the blade from the mould, and

[0017] - fixing the connection means to the contact surface of the lower housing and the contact surface of the upper housing so that the second radiating element is electrically connected to the first radiating element, thereby supplying power to the second radiating element only through the first radiating element.

[0018] The method according to the invention is more optimized since it allows integration of the radiating elements during the manufacturing process and integration of both the lightning protection system and the anti-icing system in a simple manner during blade manufacturing. A cost-reduced method is thus obtained.

[0019] These and other advantages and features of the present invention will become apparent from the accompanying drawings and detailed description of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A first embodiment of a blade according to the invention is shown in longitudinal section.

[0021] Figure 2 Shown Figure 1 Detail of the first radiating element of the blade shown in .

[0022] Figure 3 Shown Figure 1 Detail of the second radiating element of the blade shown in .

[0023] Figure 4 Shown Figure 1 The cross section of the blade along line II is shown in FIG.

[0024] Figure 5 A second embodiment of a blade according to the invention is shown in cross section.

[0025] Figure 6 A third embodiment of a blade according to the invention is shown in cross section.

[0026] Figure 7 Show Figure 1 Detail of the blade shown in.

[0027] Figure 8 A cross section of a first mould with a lower shell of a blade according to the invention is shown.

[0028] Figure 9 A cross section of a second mould with a top shell of a blade according to the invention is shown. DETAILED DESCRIPTION

[0029] Figure 1A blade 1 for a wind turbine according to the present invention is shown, comprising an anti-icing system 20 and a lightning protection system 30. Anti-icing system 20 includes a heating device 21 connected to power supply cables 40 and 41. Heating device 21 comprises at least a first radiating element 22 and at least a second radiating element 26, arranged adjacent to one another around leading edge 7 of blade 1 as shown. First radiating element 22 is connected to power supply cables 40 and 41 via respective electrical connectors 34a and 34b at respective connection points C1 and C2. In particular, first radiating element 22 is connected to first power supply cable 40 at first connection point C1 via first electrical connector 34a, and to second power supply cable 41 at second connection point C2 via second electrical connector 34b. Each power supply cable 40 and 41 extends lengthwise along blade 1 within lower shell 4 of blade 1.

[0030] The lightning protection system 30 includes at least one lightning down conductor 31, which is configured to conduct a lightning strike to the blade to the ground through the wind turbine's hub (not shown). The lightning down conductor 31 extends longitudinally from one end of the blade 1 to the blade 1. The lightning down conductor 31 is connected to each of the power supply cables 40 and 41 at connection points C1 and C2. The lightning protection system 30 also includes a lightning receptor 32 at the tip 9 of the blade 1. The lightning receptor 32 is connected to the lightning down conductor 31.

[0031] The blade 1 further comprises a surge protection device 33 (also referred to as an SPD) which connects the anti-icing system 20 with the lightning protection system 30, ensuring equal potential of the two systems 30 and 20 and avoiding arcing. The lightning down conductor 31 is arranged to be connected to each of the supply cables 40 and 41 at respective connection points C1 and C2 via respective surge protection devices 33. In particular, one surge protection device 33 is connected to the first supply cable 40 at a first connection point C1 and to the lightning down conductor 31 at a third connection point C3, and another surge protection device 33' is connected to the second supply cable 41 at a second connection point C2 and to the lightning down conductor 31 at a fourth connection point C4, as shown in FIG. Figure 2 As shown in .

[0032] The second radiating element 26 is not connected to any power supply cables 40 and 41. The second radiating element 26 is electrically connected to the first radiating element 22, so that the second radiating element 26 is powered only by the first radiating element 22.

[0033] Blade 1 includes a body 2 having an upper shell 3 and a lower shell 4, and a belly 5. Each radiating element 22 and 26 is arranged in body 2 around leading edge 7. Specifically, first radiating element 22 is arranged in lower shell 4, and second radiating element 26 is arranged in upper shell 3, such that both radiating elements 22 and 26 face each other around leading edge 7 of blade 1, but do not directly contact each other. Radiating elements 22 and 26 are arranged on lower shell 4 and upper shell 3, respectively. Specifically, radiating elements 22 and 26 are embedded in respective shells 3 and 4 and protected from external influences by an outer covering 11, which prevents any short circuits that might occur between the two radiating elements 22 and 26 arranged in close proximity. Power supply cables 40 and 41 are arranged inside lower shell 4.

[0034] Each radiating element 22 and 26 of the heating device 21 includes a resistive element 23 and 27 and electrical terminals 24a, 24b, 28a, and 28b at each end of each resistive element 23 and 27. Each electrical terminal 24a, 24b, 28a, and 28b is connected to a corresponding metal block 25 and 29, which facilitates electrical connection between the electrical terminal and the corresponding surge protection device 33 or the corresponding electrical connector 34a and 34b. In one embodiment, each metal block 25 and 29 is embedded in the corresponding housing 3 and 4. In other embodiments, each metal block 25 and 29 is fixed to the inner surface of the corresponding housing 3 and 4.

[0035] The blade 1 includes a conductive device 35, by which the second radiating element 26 is electrically connected to the first radiating element 22. In particular, at least the first terminal 24a of the first radiating element 22 and the first terminal 28a of the second radiating element 26 are arranged to be connected to each other via the conductive device 35. In an embodiment of the present invention, the second terminal 24b of the first radiating element 22 and the second terminal 28b of the second radiating element 26 are also arranged to be connected to each other via the conductive device 35. The conductive devices 35 are not embedded in the blade 1; they are fixed to the radiating elements 22 and 26 in the contact areas 12 and 13 in the upper shell 3 and the lower shell 4, where the radiating elements 22 and 26 are not covered by the outer cover 11.

[0036] In an embodiment of the invention, the conductive means 35 comprises flat conductors directly connected to the terminals 24a, 24b, 28a and 28b of the radiating elements 22 and 26 respectively. The flat conductors are preferably bonded to the contact areas 12 and 13 of the upper and lower housings 3 and 4.

[0037] In another embodiment of the invention, the conducting means 35 comprises a metal mesh directly attached to the terminals 24a, 24b, 28a and 28b of the radiating elements 22 and 26 respectively. The flat conductors are preferably to the contact areas 12 and 13 of the upper 3 and lower 4 housings.

[0038] In an embodiment, the blade 1 comprises: an additional surge protector device 33', which connects the lightning down conductor 31 with the second power supply cable 41, so that one end of the additional surge protector device 33' is connected to the third connection point C3; and another additional surge protector device 33', which connects the lightning down conductor 31 with the first power supply cable 40, so that one end of the additional surge protector device 33' is connected to the fourth connection point C4.

[0039] Each surge protection device 33 and 33' is called an SPD and operates as a switch that closes for the brief duration of a surge. That is, it operates as an open switch that prevents current flow when a specific voltage is not exceeded, and as a closed switch when a specific voltage is exceeded. When the specified voltage is exceeded, the overvoltage current can flow to the ground through the lightning down conductor 31 or to the power grid through the corresponding supply cables 40 and 41. This type of short circuit lasts only for the duration of the surge, typically a few microseconds. The surge protection device 33 can be based on spark gap technology. In other embodiments, the surge protection device is based on varistor technology and / or gas discharge tubes or other technology.

[0040] In an embodiment, the radiating elements 22 and 26 are resistive elements. Preferably, the radiating elements 22 and 26 comprise biaxial carbon fabric.

[0041] In an embodiment, the electrical terminals 24a, 24b, 28a and 28b of the radiating elements 22 and 26 are wire meshes, preferably made of copper, attached to the resistive elements 23 and 27.

[0042] In an embodiment, the blade 1 is made of carbon fiber and includes a carbon beam 8 extending longitudinally on the belly 5. In these blades 1 made of carbon fiber, one end of the surge protection device 33 is connected to the corresponding carbon beam 8. Similarly, one end of the auxiliary surge protection device 33' is connected to the corresponding carbon beam 8.

[0043] exist Figure 4 、 Figure 5 、 Figure 8 and Figure 9 In the embodiment shown in FIG, the blade 1 is made of carbon fiber as described above. The lightning down conductor 31 and the power supply cables 40 and 41 extend along the core 5 and, in particular, are arranged in the lower shell 4. The blade 1 includes a surge protection device 33 in the lower shell 4, which is connected at one end to the first power supply cable 40 at a first connection point C1 and at the other end to the lightning down conductor 31 at a third connection point C3 and to the carbon beam 8 included in the lower shell 4.

[0044] Blade 1 includes another surge protection device 33 in lower housing 4, which is connected at one end to the second power supply cable 41 at a second connection point C2 and at the other end to the lightning down conductor 31 and to the carbon beam 8 included in lower housing 4 at a fourth connection point C4. Furthermore, blade 1 includes an auxiliary surge protection device 33' located in lower housing 4 and connected at one end to the second power supply cable 41 and at the other end to the carbon beam 8 and lightning down conductor 31 located in lower housing 4. Blade 1 also includes metal blocks 25 and 29, each fixed to a respective inner surface of lower housing 4 and upper housing 3, to which electrical connectors 34a and 34b of radiating elements 22 and 26 are fixed. A first power supply cable 40 is connected to the respective metal block 25 in lower housing 4, and surge protection device 33 is connected to the respective metal block 29 in upper housing 3.

[0045] Finally, the blade 1 comprises in the upper shell 3 a surge protection device 33 connected at one end to the second radiating element 26 and at the other end to the carbon beam 8 .

[0046] exist Figure 5 In another embodiment of the present invention shown in , the blade 1 is also made of carbon fiber, but includes a lightning down conductor 31 in each shell 3 and 4 of the main body 2, that is, it includes a lightning down conductor 31 in the lower shell 4 and another lightning down conductor 31 in the upper shell 3. The lightning down conductor 31 in the upper shell 3 is connected to the second radiating element 26 through another surge protection device 33, and the lightning protection system 30 is equalized in the two shells 3 and 4 through the electrical connection between the first radiating element 22 and the second radiating element 26. Preferably, both lightning down conductors 31 are embedded in the respective shells 3 and 4.

[0047] The electrical connections between the first radiating element 22, the power supply cables 40 and 41, and the lightning down conductor 31 housed in the lower housing 4 are as follows: Figure 4 The electrical connections are similar to those described in the previous embodiment shown in FIG.

[0048] In the upper shell 3 , one end of a surge protection device 33 is connected to a lightning down conductor 31 , which is also connected to the spar 8 .

[0049] exist Figure 6In another embodiment shown in FIG, the blade 1 is made of fiberglass and does not include a carbon beam. The blade 1 includes a lightning down conductor 31 and a surge protection device 33 in the lower housing 4. The surge protection device 33 is connected to the first power supply cable 40 at a first connection point C1 at one end and to the lightning down conductor 31 at the other end. The blade 1 also includes an auxiliary surge protection device 33' housed in the lower housing 4. The auxiliary surge protection device 33' is connected to the second power supply cable 41 at one end and to the lightning down conductor 31 at the other end.

[0050] Finally, the heating element 21 may include a plurality of first radiating elements 22 located in the lower housing 4 and a plurality of second radiating elements 26 located in the upper housing 3, both radiating elements 22 and 26 being arranged along the leading edge 7 of the blade 1 and facing each other. In the embodiment shown in the figures, the heating device 21 includes three first radiating elements 22 and three second radiating elements 26 arranged opposite each other.

[0051] Another aspect of the present invention is a method for manufacturing a blade having the aforementioned characteristics. The method comprises the following steps:

[0052] - depositing in a first mould 50 a plurality of fabric layers or sheets 10 that will form the lower shell 4 of the blade 1, at least one first radiating element 22 in the leading edge region 53 of the first mould 50, and at least one connecting element 55 in contact with the cavity 51 of the first mould 50 and with one of the electrical terminals 24a, 24b of the first radiating element 22, the connecting element 55 being configured to define in the lower shell 4 a contact surface 12 situated above the first radiating element 22, in particular above the electrical terminals 24a, 24b of the first radiating element 22;

[0053] - Molded lower housing 4;

[0054] - connecting the first electrical terminal 24a of the first radiating element 22 to the first power supply cable 40, connecting the second electrical terminal 24b of the first radiating element 22 to the second power supply cable 41, and connecting the lightning down conductor 31 to each power supply cable 40 and 41 through a corresponding surge protection device 33;

[0055] - depositing in a second mould 60 a plurality of fabric layers or sheets 10 that will form the upper shell 3 of the blade 1, comprising at least one second radiating element 26 situated in the leading edge region 63 of the second mould 60, and at least one connecting element 65 in contact with the cavity 61 of the second mould 60 and with the terminals 28a and 28b of the second radiating element 26, the connecting element 65 being configured to define in the upper shell 3 a contact surface 64 situated above the second radiating element 26, in particular above the electrical terminals 28a and 28b of the second radiating element 26;

[0056] - closing the two molds 50 and 60 relative to each other, wherein the connecting elements 12 of the first mold 50 and the connecting elements 13 of the second mold 60 face each other and sealing the upper shell 3 and the lower shell 4 to each other;

[0057] - removing the blade 1 from the moulds 50 and 60; and

[0058] fixing the conductive means 35 to the contact surface 55 of the lower housing 4 and to the contact surface 65 of the upper housing 3 such that the second radiating element 26 is electrically connected to the first radiating element 22 , so that the second radiating element 26 is powered only via the first radiating element 22 .

[0059] The leading edge regions 53 and 63 of the first and second moulds 50 , 60 form the leading edge 7 of the blade 1 .

[0060] Each connecting element 55 and 65 is arranged in a specific area of ​​the corresponding leading edge region 53 and 63, creating a corresponding contact surface 12 and 13 on the blade 1. The contact surfaces 12 and 13 face each other. In each mold 50 and 60, the connecting elements 55 and 65 are arranged to contact the cavity-delimiting surfaces 52 and 62 of the corresponding cavity 51 and 61, and to contact the radiating elements 22 and 26.

[0061] In the contact surfaces 12 and 13, the first radiating element 22 and the second radiating element 26 are not covered by the outer coating 11 or any other fiber or fabric, i.e., they are exposed and visible. In particular, these contact areas 12 and 13 are formed at least on the first terminal 24a of the first radiating element 22 and the first terminal 28a of the second radiating element 26.

[0062] The lower housing 4 and the upper housing 3 are molded using a vacuum injection process. Once the plurality of fabric layers or sheets 10, the first radiating element 22, and the corresponding connecting elements 55 are deposited in the cavities 51 and 61, a vacuum is applied and resin is injected into the corresponding mold cavities 51 and 61. After curing, the lower housing 4 and the upper housing 3 are obtained, respectively.

[0063] In one embodiment, the metal blocks 25 and 29 are fixed to the respective housings 3 and 4 after curing, and the respective radiating elements 22 and 26 are connected to said metal blocks 25 and 29. In another embodiment, each metal block 25 and 29 is arranged between a plurality of layers 10, embedded therebetween.

[0064] exist Figure 5In the embodiment shown in FIG, one lightning down conductor 31 is arranged in each mold 50 and 60. The second radiating element 26 is connected to another lightning conductor 31 via another surge protection device 33 housed in the upper housing 3, and the lightning protection system 30 is connected to the same potential in both housings 3 and 4 via the conductive device 35. In this embodiment, both lightning down conductors 31 are embedded in the respective housings 3 and 4. The respective lightning down conductors 31 are connected to the respective spar 8 before the vacuum is applied.

[0065] Once the lower housing 4 is molded, the belly 5 is fixed to the lower housing 4. Subsequently, the power supply cables 40 and 41 are arranged to be guided along the core 5. The first radiating element 22 is connected to the corresponding metal block 25. Thereafter, the electrical connections between the corresponding electrical connectors 34a and 34b, the first power supply cable 40, the second power supply cable 41, the surge protection devices 33 and 33', and the lightning down conductor 31 are made as previously described in the specification.

[0066] Before closing the two molds 50 and 60, the corresponding electrical connections between the first radiating element 22, the power supply cables 40 and 41, the lightning down conductor 31 and the corresponding surge protection devices 33 and 33' are made in the first mold 50 as described above. The electrical connections of the elements housed / included in the upper housing 3 and the elements housed / included in the lower housing 4 are connected independently of each other.

[0067] Once the blade 1 has been demoulded, the respective connecting elements 55 and 65 are removed from the respective contact surfaces 12 and 13 on which the conductive means 35 were fixed.

[0068] In the embodiment, each connecting element 55 and 65 has a rectangular geometry, resulting in a substantially rectangular contact surface 12 and 13 .

[0069] In a preferred embodiment, the conductive device 35 is bonded to the contact surface 12 of the lower shell 4 and the contact surface 13 of the upper shell 3. After the blade 1 is demolded, the conductive device 35 is secured to the contact surfaces 12 and 13 by curing the adhesive. Specifically, each connecting element 55 and 65 is an adhesive tape, preferably made of plastic, placed in each mold 50 and 60 to define the contact surfaces 12 and 13. Once the blade 1 is removed from the molds 50 and 60, the adhesive tape is removed. Once the adhesive tape is removed, the conductive device 35 is bonded to the adhesive-impregnated contact surfaces 12 and 13. In both cases, pressure can be applied to the conductive device 35 to enhance the securing process.

[0070] In other embodiments, the conductive device 35 may be secured to the contact surfaces 12 and 13 by any other known means.

[0071] In an embodiment, the layer 10 may be a carbon layer or sheet, and the first and second molds 50 and 60 contain the carbon beams 8 such that the carbon beams 8 are embedded in the blade 1. The carbon beams 8 included in the first mold 50 and the second mold 60 are electrically connected to the corresponding surge protection devices 33 and 33' and / or the lightning down conductor 31, as previously described in the specification.

[0072] In other embodiments where the blade 1 comprises a plurality of first radiating elements 22 and a plurality of second radiating elements 26, each mould 50 and 60 will comprise at least one connecting element 55 and 65 for each first radiating element 22 and for each second radiating element 26, said connecting elements 55 and 65 being arranged facing each other.

[0073] What is described for the blade in any embodiment and / or configuration thereof is also valid for embodiments and / or configurations of the method for manufacturing the blade.

Claims

1. A blade for a wind turbine, comprising an anti-icing system (20), a lightning protection system (30), and a surge protection device (33) connecting the anti-icing system (20) and the lightning protection system (30) to ensure equipotentiality of the two systems (30, 20), the anti-icing system comprising a heating device (21) connected to power supply cables (40, 41), the lightning protection system comprising at least one lightning down conductor (31) and being configured to conduct lightning striking the blade (1) to the ground through the lightning down conductor (31), characterized in that The heating device (21) comprises at least one first radiating element (22) and at least one second radiating element (26), which are arranged facing each other around the leading edge (7) of the blade (1), wherein the first radiating element (22) is connected to the power supply cables (40, 41) at respective connection points (C1, C2) via respective connectors (34a, 34b), and the lightning down conductor (31) is connected to each power supply cable (40, 41) at the connection points (C1, C2) via respective surge protection devices (33), and the second radiating element (26) is electrically connected to the first radiating element (22) so that the second radiating element (26) is powered only via the first radiating element (22).

2. The blade according to claim 1, wherein The first radiation element (22) is arranged on the lower shell (4) of the blade (1), and the second radiation element (26) is arranged on the upper shell (3) of the blade (1).

3. The blade according to claim 2, wherein: The lightning protection system (30) comprises another lightning down conductor (31) located in the upper housing (3) and connected to the second radiating element (26) via another surge protection device (33); the lightning protection system (30) is at equal potential in the two housings (3, 4) through the electrical connection between the first radiating element (22) and the second radiating element (26).

4. The blade according to any one of claims 1 to 3, comprising conducting means (35) configured to electrically connect the second radiating element (26) with the first radiating element (22).

5. The blade according to claim 4, wherein: The first radiating element (22) and the second radiating element (26) respectively include a first terminal (24a, 28a) and a second terminal (24b, 28b), wherein the first two terminals (24a, 28a) of the radiating elements (22, 26) and / or the second two terminals (24b, 28b) of the radiating elements (22, 26) are connected to each other by the conductive means (35) attached to the corresponding terminals (24a, 24b, 28a, 28b).

6. The blade according to claim 5, wherein: The conductive means (35) comprises a flat conductor or a metal mesh directly attached to the respective terminals (24a, 24b, 28a, 28b).

7. The blade according to any one of claims 1 to 3, wherein: The first radiating element (22) is connected to a first power supply cable (40) at a first connection point (C1), and the blade (1) comprises an additional surge protection device (33') which connects the lightning down conductor (31) to a second power supply cable (41) at the first connection point (C1).

8. A blade according to any one of claims 1 to 3, comprising longitudinally extending spar wings (8), each surge protector device (33, 33') being connected to a respective spar wing (8).

9. The blade according to any one of claims 1 to 3, wherein: The heating device (21) comprises a plurality of first radiation elements (22) and a plurality of second radiation elements (26) arranged around the leading edge (7) of the blade (1).

10. The blade according to claim 3, wherein The lightning down conductor (31) located in the lower shell (4) and the lightning down conductor (31) located in the upper shell (3) are embedded in the corresponding upper shell (3) and lower shell (4).

11. A method for manufacturing a blade for a wind turbine according to any one of the preceding claims 1 to 10, comprising the following stages: - depositing in a first mould (50) a sheet of fabric (10) that will form the lower shell (4) of the blade (1), at least one first radiating element (22) in the leading edge region (53) of the first mould (50), and at least one connecting element (55) in contact with the cavity (51) of the first mould (50) and one of the electrical terminals (24a, 24b) of the first radiating element (22), the connecting element (55) being configured to define in the lower shell (4) a contact surface (12) above the electrical terminals (24a, 24b) of the first radiating element (22), - Moulding of the lower housing (4), - connecting the first electrical terminal (24a) of the first radiating element (22) to the first power supply cable (40), connecting the second electrical terminal (24b) of the first radiating element (22) to the second power supply cable (41), and connecting the lightning down conductor (31) to each of the first power supply cable (40) and the second power supply cable (41) via a corresponding surge protection device (33), - depositing in a second mould (60) a plurality of fabric sheets (10) that will form the upper shell (3) of the blade (1), comprising at least one second radiating element (26) located in the leading edge region (63) of the second mould (60) and at least one connecting element (65) in contact with the cavity (61) of the second mould (60) and one of the electrical terminals (28a, 28b) of the second radiating element (26), the connecting element (65) being configured to define in the upper shell (3) a contact surface (13) located above the electrical terminals (28a, 28b) of the second radiating element (26), - Moulding the upper housing (3), - closing the two moulds (50, 60) against each other, with the connecting element (55) of the first mould (50) and the connecting element (65) of the second mould (60) facing each other, and sealing the two shells (3, 4), thereby forming the blade (1), - demoulding the blade (1) from the mold (50, 60), removing the connecting elements (55, 65), and - fixing the conducting means (35) to the contact surface (12, 13) created by removing the connecting element (55, 65), so that the second radiating element (26) is supplied with power only through the first radiating element (22).

12. The manufacturing method according to claim 11, wherein: A metal block (25) is at least fixed to the lower housing (4) or at least embedded in the lower housing (4), and the first radiation element (22) and the first power supply cable (40) are connected to the metal block (25).

13. The manufacturing method according to claim 11 or 12, wherein: Once the upper housing (3) is formed and before closing the two moulds (50, 60), the second radiating element (26) is connected to another lightning down conductor (31) via another surge protection device (33) housed in the upper housing (3), the lightning protection system (30) being at equal potential in the two housings (3, 4) via the conductive device (35).

14. The manufacturing method according to claim 11 or 12, wherein: In each mold (50, 60), the connecting element (55, 65) is arranged in contact with the surface of the corresponding cavity (51, 61) and in contact with the radiating element (22, 26).

15. The manufacturing method according to claim 11 or 12, wherein: The conductive means (35) is bonded to the contact surfaces (12, 13).

16. The manufacturing method according to claim 11 or 12, wherein: The connecting element (55, 65) is an adhesive tape which is placed in each mould (50, 60) to define the contact surface (12, 13), and once the blade (1) is demoulded, the connecting element (55, 65) is removed and the conductive device (35) is bonded to the adhesive-impregnated contact surface (12, 13).

17. The manufacturing method according to claim 15, wherein: The conductive means (35) is bonded to the contact surface by a curing adhesive.

18. The manufacturing method according to claim 16, wherein: The connecting elements (55, 65) are made of plastic.

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