WO2011127995A1

WO2011127995A1 - Fixation of a heating mat to a blade of a wind turbine

Info

Publication number: WO2011127995A1
Application number: PCT/EP2010/063590
Authority: WO
Inventors: Soeren Oemann Lind; Finn Daugaard Madsen; Karsten Schibsbye
Original assignee: Siemens Aktiengesellschaft
Priority date: 2010-04-12
Filing date: 2010-09-16
Publication date: 2011-10-20
Also published as: DK2526292T3; CN102822517B; CA2795982C; CA2795982A1; CN102822517A; EP2526292B1; US9341164B2; EP2526292B8; US20130195661A1; EP2526292A1

Abstract

The present invention describes a blade (100) for a wind turbine. The blade (100) comprises at least one heating mat (101) for generating heat, wherein the heating mat (101) is mounted at an outer surface (104) of the blade (100). The blade (100) further comprises at least one through-hole (102) running from an inner space (103) of the blade (100) to the outer surface (104) of the blade (100). The blade (100) further comprises at least one conductive element (105), wherein the conductive element (105) is electrically coupled to the heating mat (101). The conductive element (105) is inserted in the through-hole (102) for generating an electric connection between the inner space (103) and the outer surface (104).

Description

DESCRIPTION

Fixation of a heating mat to a blade of a wind turbine

Field of invention

The present invention relates to a blade for a wind turbine and to a method of manufacturing a blade with a heating sys- tern for a wind turbine.

Art Background Icing on any exposed part of a wind turbine can occur and cause decreased performance of the wind turbine. Furthermore e.g. when ice is accumulated on one or more of the rotor blades of a wind turbine, excess vibration problems from un^¬ even blade icing may occur. This in turn may generate exces- sive mechanical loads on the wind turbine components leading eventually to wind turbine shut-down or to wind turbine faults .

Hence, it is necessary to avoid ice or to remove ice located on wind turbine blades by a deicing system or by a heating system. In particular, it is known to use an electrical heating that is attached to an outer surfaces of the blade.

The heating is connected by electrical wiring to a power sup- ply and to a control unit. The wiring can be damaged by lightning strikes, because the conductors run along the outer surface of the blade to the location of the heating. In par^¬ ticular, there is a need to heat the tip ends of the blades, so that in conventional heating systems a conductor has to run from the tip end to the root end of the blade. In par^¬ ticular, in the region of the tip end of the blade, the risk is severe that the conductor running to the heating being hit by a lightning strike. Summary of the Invention The object of the present invention is to provide a heating for a blade of a wind turbine with a robust heating system and a proper electrical connection.

This object is solved by a blade for a wind turbine and by a method for manufacturing a blade with a heating system for a wind turbine according to the independent claims.

According to a first aspect of the invention, a blade for a wind turbine is presented. The blade comprises at least one heating mat for generating heat, wherein the heating mat is mounted to the blade, e.g. to an outer surface of the blade inside a laminate of the blade or to an inner space of the blade. Moreover, the blade comprises at least one through- hole running from an inner space of the blade to the outer surface of the blade. Moreover, the blade comprises at least one conductive element wherein the conductive element is electrically coupled to the heating mat. The conductive ele^¬ ment is inserted in the through-hole for generating an elec^¬ trical connection between the inner space and the outer sur- face of the blade.

According to a further aspect of the invention, a method of manufacturing a blade with a heating system for a wind turbine is presented. At an outer surface of the blade at least one heating mat for generating heat is mounted. At least one through-hole is formed into the blade, wherein the through- hole runs from an inner space of the blade to the outer sur^¬ face of the blade. At least one conductive element is in^¬ serted in the through-hole for generating an electrical con- nection between the inner space and the outer surface. The conductive element is electrically coupled to the heating mat . The conductive element which is inserted in a through-hole of the blade may comprise a bushing, a cable, a bolt or other conductive elements that connects the inner space of the blade to the outer surface of the blade.

The heating mat is generally formed as a flat stripe-shaped mat extending in a longitudinal direction. The longitudinal direction defines the direction between two end points of the heating mat (in particular the direction or distance between two end points parallel to a plane that is parallel to the blade surface) between which the length of the heating mat is defined. The height extends vertically (in particular paral^¬ lel to a normal of the (plane of the) outer blade surface) form the outer surface of the heating mat, and the width of the heating mat is the distance from side to side, measuring across the heating mat at right angles to the length. The width is shorter than the length of the heating mat. The width may be approximately 25 cm (centimeter) to 1,50 m (me^¬ ter) , preferably approximately 55 cm. The length of the heat- ing mat may be generally twice as much as the length of the blade. The heating mat may comprise a length of approximately 60 m to 200 m (meter) , preferably 90 m. Accordingly, the blade may have a length of approximately 30 m to 100 m (me^¬ ter) . The height of the heating mat may be approximately 0,5 mm (Millimeter) cm to 1 cm (centimeter) . Preferably, the heating mat comprises an area density of the fibers of ap^¬ proximately 400 g/m² to 800 g/m², in particular approximately 600 g/m² (grams per square meter) . On opposed ends along the longitudinal (extending) direction, the first end section and the second end section are formed. To the first end section and the second end section a power input and/or a power out^¬ put connection may be attached.

By the power terminals, a voltage of 100 V AC to 1000 V

(Volt) AC is applicable. In a static condition of the blades or the wind turbine, a voltage of 400 V AC the heating mat may generate a temperature of approximately 10° C (Celsius) and a voltage of 650 V AC to 750 V AC may generate a tempera- ture of approximately 20° C to 30° C. This may though vary in dependency of the chosen heating mat area density and heating mat area. In a working condition of the blades, it is desired to apply a voltage for generating a heat by the heating mat along the surface of the blade of approximately a temperature of 2° C to 4° C in order to have a proper de-icing effect.

By the present invention, the power supply for the heating mat is directed by the conductive element in the through-hole from the inside of the blade to the outside of the blade. Thus, long power connecting wires along the surface of the blade may be obsolete. The through-hole may be formed in the blade at a region, where the heating mat is located on the outer surface, so that the conductive element runs from the heating mat directly through the through-hole to an inner re^¬ gion of the blade without running along the outer surface of the blade.

This has the technical effect, that the risk of damages in the power supply may be reduced. In particular lightning strikes at the blade may cause damage to conductors running along the outer surface of the blade. By the present inven^¬ tion, the through-hole is formed inside the blade, so that the run of a connector along the outer surface of the blade is reduced and thus the risk that the conductor along the outer surface is getting hit by a lightning strike is reduced as well.

In order to provide the electrical coupling of the heating mat to a power supply, a plurality of through-holes with in^¬ serted conductive elements may be formed into the blade.

Thus, a plurality of electrical connections to the heating mat is generated. For example, in each through-hole separate power in and power out connections to the conducting elements or power cables are coupleable. Furthermore it is outlined, that as well more than on heating mats that are electrically coupled to a respective coupling element in a through-hole are mountable to the blade in an exemplary embodiment. According to a further exemplary embodiment, the heating mat comprises (electrical conducting) carbon fibres for generat^¬ ing heat. Carbon fibres are very robust, so that the risk of damage due to a lightning strike may be reduced. Moreover, the carbon fibres of the heating mat may be flexibly woven and thus adapted to the requirements of the blade to be heated. For instance, it may be beneficial to provide a higher density of the woven carbon fibres along the leading edge of the blade, so that more heat is produced in this leading edge area. Alternatively or additionally, the heating mat may also be made of other conductive materials, such as metal, e.g. copper fibres, or conductive synthetic material. According to a further exemplary embodiment, the blade further comprises a root end section with a fixing element for fixing the blade to a hub of the wind turbine. The through- hole is formed in the root end section. The fixing elements in the root end section are for instance fixing bolts for fixing a blade to a holder (hub) of the blades of the wind turbine. The root end section is located on the opposite side of the tip end of the blade with respect to a longitudinal direction of the blade. In particular, the root end section may describe the first half of the blade starting from the root end running along the longitudinal di^¬ rection of the blade. In particular, the root end section may define one third, one fourth, one fifth of the blade section starting from the root end of the blade in longitudinal di- rection to the tip end. In particular, the root end section may define the section on the blade that extends from the root end approximately 1 m, 2 m, 5 m, 10 m or 20 m in the longitudinal direction to the tip end of the blade for in^¬ stance .

According to a further exemplary embodiment, the conductive element comprises an outer section which protrude from the outer surface and an inner section which extends into the in- ner space. A conductor is fixable to the inner section for supplying power from a power supply unit to the conductive element, and wherein the heating mat is electrically con^¬ nected to the outer section.

The conductor element is for instance a cable or a strip con^¬ ductor attached to an inner surface of the blade. The conduc^¬ tor elements may be connected to a power supply that is at^¬ tached within the blade or within the housing of the wind turbine. Thus, by using for example a slip ring connection between the conductor element and the power supply a power connection between the rotating blade and the housing element may be achieved. By the present exemplary embodiment, the conductor runs in^¬ side an inner space of the blade to the through-hole and to the conductive element inserted in the through-hole, respec^¬ tively. Thus, the conductor for supplying power is located inside the blade, so that it is not necessary to provide a long run of a conductor at the outer surface of the blade.

Thus, the risk of being hit by a lightning strike is reduced.

According to a further exemplary embodiment, the conductive element comprises a conductive bolt. The conductive bolt is fixed to the through-hole in such a way that between a bolt head of the conductive bolt and the outer surface the heating mat is clamped for generating an electrically conductive clamping connection. The bolts may comprise a screw with a clamping nut. Moreover, the bolt may comprise an integrally formed bolt head or a washer for increasing the clamping area between e.g. the washer and the heating mat. Thus, by generating an electrically conductive clamping con^¬ nection between the conductive element and the heating mat, it is not necessary to provide e.g. connection holes within the heating mat. By the clamping connection, an easy connec- tion between the heating mat and the power supply is

achieved .

According to a further exemplary embodiment, the blade com- prises a conductive sheet. The conductive sheet is mounted to the outer surface by the conductive bolt and is electrically coupled to the heating mat. The conductive sheet may increase the contact area and the clamping area between the bolt and the heating mat. Thus, a proper electrical and mechanical connection is achieved.

According to a further exemplary embodiment, the blade further comprises a conductive bushing fixed inside the through- hole. The conductive bolt is fixed in the conductive bushing. Thus, a proper electrical connection with an improved effi^¬ ciency is achieved.

According to a further exemplary embodiment, the blade further comprises a conductive mesh that is interposed between the conductive element and the heating mat. By using the con^¬ ductive mesh, e.g. a metal mesh, a larger contact area be^¬ tween the heating mat and the conductive element is gener^¬ ated. By using the conductive mesh, the contact area is in^¬ creased, without causing a high weight. In particular, the conductive mesh may be wrapped around an end section of the heating mat and partially enveloping the heating mat. Thus, in particular when connecting the heating mat by a clamping connection, an improved electrical and mechanical connection is achievable.

The conductive mesh may comprise steel, aluminium, copper or carbon material.

According to a further exemplary embodiment, the blade fur- ther comprises an adhesive layer for generating a laminate out of the conductive element and the heating mat. Thus, by using e.g. resin as adhesive for forming the adhesive layer, a rigid and robust connection between the conductive element and the heating mat is achievable without negatively effect^¬ ing the electrical connection between the conductive element and the heating mat. According to a further exemplary embodiment, the blade further comprises a cover layer, wherein the cover layer covers the heating mat, the conductive element and the outer surface such that a homogeneous outer layer of the blade is formed. The cover layer leads to a homogeneous and smooth profile of the blade, so that the aerodynamic characteristics are not affected due to a fixation of the heating mat to the outer surface of the blade. Moreover, the cover layer may comprise protection characteristics, so that a robust blade is achiev- able. The cover layer may comprise for instance glass fibre material .

According to a further exemplary embodiment, the heating mat comprises a first end section and a second end section. The second end section defines an opposite end section of the heating mat in a longitudinal direction of the heating mat with respect to the first end section. The blade further com^¬ prises a power transmitting section located on the outer surface. The power transmitting section comprises the through- hole and the conductive element for supplying power to the heating mat. The first end section and the second end section are located inside the power transmitting section and are electrically connected to the conductive element. The heating mat comprises a first section running from the first end sec- tion to a region outside of the power transmitting section. The heating mat comprises a second section running from the region outside of the power transmitting section to the second end section inside the power transmitting section. According to a further exemplary embodiment, the heating mat is mounted at an outer surface of the blade. The heating mat comprises a first section with a first end section and a sec^¬ ond section with a second end section. The first end section and the second end section are electrically connectable (e.g. by a cable) to a respective power terminal for supplying power to the heating mat. The second end section defines an opposite end section of the heating mat in the longitudinal direction of the heating mat with respect to a first end sec^¬ tion. The first section and the second section run along the surface of the blade in one or more loops from the first end section to the second end section. Moreover, the heating mat may comprise a transition section that connects the first section and the second section out^¬ side of the power transmitting section.

The heating mat comprises a run parallel to the plane of the blade surface with e.g. a half-loop shape within a plane that is in general parallel to the plane of the blade surface. The heating mat runs from one through-hole which provides a con^¬ nection to a power terminal to the outside of the power transmitting section and after a half loop (e.g. a curve with approximately 180 degrees) the heating mat runs back from outside of the power transmitting section inside to the power transmitting section, where the second end section of the heating mat is finally connected to the conductive element in a further through-hole for providing a connection to a fur- ther power terminal. The section of the heating mat that connects the first section and the second section outside of the power transmitting section is the transition section.

By the exemplary embodiment, a blade is presented that com- prises the heating mat that forms a half loop and/or a plu^¬ rality of loops, wherein in one common power transmitting section the first end section and the second end section are connected to a power supply via the power terminals. Thus, the electrical connection and thus the sole necessary elec- trical wiring have to be applied at the power transmitting section and not in another section of the blade, such as the tip end section. This has the technical effect, that no electrical connec^¬ tions, such as electrical wires, are needed to be mounted and connected along the blade surface except in the power trans^¬ mitting section, in which the through-holes and the end sec- tions of the heating mat are located. Thus, less risk of dam^¬ ages to the heating mat due to lightning strikes or other physical impacts are reduced.

According to a further exemplary embodiment of the method, the mounting comprises an adding of an adhesive to the heat^¬ ing mat and the outer surface for forming a laminate and a curing of the adhesive.

Thus, in the production and manufacturing process of the blade, the heating mat and the electrical connection are manufactured simultaneously. In particular, the heating mat may be attached to the outer surface of the blade and by a vacuum resin moulding or resin transfer moulding method, for example, the blade including the heating mats is easy to manufacture.

Summarizing, by the present invention the power is supplied from the inner space of the blade through the through-hole to the outer surface of the blade, where the heating mat is at- tached. In particular, by the above-described invention, a good electrical connection of the (carbon fibre) heating mat as well as the supplying of an electrical connection through the through-hole of the blade is achieved. According to the present invention one (or a plurality of) heating mats that comprises electrical connections e.g. at the root end section of the blade is e.g. mechanically con^¬ nected to a conductive element in a through-hole or is at^¬ tached to the conductive element by a vacuum pressed resin moulding method, for example.

By an exemplary embodiment of the present invention, for instance conductive meshes for increasing the clamping area be- tween the conductive element and the heating mat are applica^¬ ble, so that a proper electrical connection with a low resis^¬ tance is achieved. In this way, electrical power is saved during deicing of the blade, so that the heating is more ef- ficient.

In particular, by locating the through-holes for providing the electrical connections in the root end part of the blade, the risk of damage of the electrical connection due to light- ning strikes is reduced.

It has to be noted that embodiments of the invention have been described with reference to different subject matters. In particular, some embodiments have been described with ref- erence to apparatus type claims whereas other embodiments have been described with reference to method type claims. However, a person skilled in the art will gather from the above and the following description that, unless other noti^¬ fied, in addition to any combination of features belonging to one type of subject matter also any combination between features relating to different subject matters, in particular between features of the apparatus type claims and features of the method type claims is considered as to be disclosed with this application.

Brief Description of the Drawings

The aspects defined above and further aspects of the present invention are apparent from the examples of embodiment to be described hereinafter and are explained with reference to the examples of embodiment. The invention will be described in more detail hereinafter with reference to examples of embodi^¬ ment but to which the invention is not limited.

Fig. 1 shows a schematical view of an exemplary embodiment of the present invention; Fig. 2 shows schematically a conductor for the conductive element according to an exemplary embodiment of the present invention ; Fig. 3 shows schematically a clamping connection between the heating mat and the conductive element according to an exem^¬ plary embodiment of the present invention; and

Fig. 4 illustrates a schematical view of a run of a heating mat in a half loop according to an exemplary embodiment of the present invention.

Detailed Description

The illustrations in the drawings are schematical. It is noted that in different figures, similar or identical ele^¬ ments are provided with the same reference signs. Fig. 1 shows a blade 100 for a wind turbine. The blade 100 comprises a heating mat 101 for generating heat, wherein the heating mat 101 is mounted to an outer surface 104 of the blade 100. Moreover, a through-hole 102 is shown, wherein the through-hole 102 runs from an inner space 103 of the blade 100 to the outer surface 104 of the blade 100. Moreover, the blade 100 comprises a conductive element 105, wherein the conductive element 105 is electrically coupled to the heating mat 101. The conductive element 105 is inserted in the through-hole 100 for generating an electric connection be- tween the inner space 103 and the outer surface 104.

As shown in Fig. 1, the conductive element 105 comprises a bushing and/or a bolt, wherein both, the bushing and/or the bolt are electrically conductive.

In the inner space 103 of the plate 100 a conductor 106, such as a conductor cable, may be guided inside of the blade 100 to a power supply. The power supply may be located in a hub or in a housing of the wind turbine, wherein by a slip ring connection a power connection between the conductor 106 and the power supply may be generated. On the outer surface 104 of the blade 103 the conductive element 105, such as the bolt, is connected to a power connection of the heating mat 101. The through-hole 102 is located close to the power con^¬ nection of the heating mat 101, so that a conductor running along the outer surface 104 from the conductive element 105 to the heating mat 101 is obsolete or the lengths of the run of the conductor at the outer surface is very short.

Fig. 2 illustrates schematically a further exemplary embodi^¬ ment, wherein to the blade 103 a through-hole 102 connecting the inner space 103 and the outer surface 104 is drilled. A conductor 105, such as a cable, directly connects the heating mat 101 with a power supply.

The through-hole 102 may comprise a distance along the outer surface 104 to the heating mat 101 for example of approxi- mately 10 cm, 50 cm, 1 m or 2 m (meter) .

Fig. 3 shows the heating mat 101 that is clamped by a clamp^¬ ing connection to the conductive element 105. The conductive element 105 is for example a conductive bolt that comprises a bolt head 303. Between the bolt head 303 and the heating mat 101 an electrical conductive block of a material and/or a conductive sheet 304 may be interposed in order to improve the clamping connection by increasing the clamping area between the heating mat 101 and the conductive sheet 304. Addi- tionally, by increasing the clamping area, the electrical conductivity between the conductive element 105 and the heat^¬ ing mat 101 is improved as well. From the outer surface 104 an outer section 301 of the conductive element 105 protrudes. At the outer section 301 of the conductive element 105 the clamping means, such as the conductive sheet 304 or the con^¬ ductive mesh 305, are attached. The conductive element 105 protrudes also to the inner space 103, wherein the protruding section of the conductive element 105 forms an inner section 302. To the inner section 302 a washer or a further conductive sheet may be attached. A conductor 106 is clamped to the inner section 302 of the conductive element 105. The conduc^¬ tor 106 runs to a power supply.

By the exemplary embodiment of Fig. 3, an end section of the heating mat 101, that is located preferably in the root end section of the blade 100, is clamped together with a copper block (conductive sheet 304) and the copper grid or mesh 305 by one or more conductive elements 105, such as bolts. The conductive element 105 (e.g. the bolts) runs through the through-hole 102 of the blade 100 from the inner space 103 to the outer surface 104. The heating mat 101 may be for example a carbon fibre heating mat. The heating mat 101 is for example pressed together with the conductive mesh 305 and the conductive element 105. A setting material or an adhesive, e.g. an epoxy or a polyester resin, is applied to the heating mat 101, the conductive mesh 305 and the conductive element 105 on the blade 101. Next, all components are pressed together. The setting material is removed by a vacuum. After curing, the heating mat and the other components are firmly attached to the blade 101. Thus, a laminate is produced.

Fig . 4 shows a strip-like shaped heating mat 101 that runs with a half loop run. The heating mat 101 comprises a first end section 401 and a second end section 402. The first end section 401 and the second end section 402 of the heating mat 101 are located inside a power transmitting section 403 that is formed close to the root end of the blade 101. In the root end fixing elements 408 for fixing the blade to a hub of a wind turbine are installed. In order to gener- ate an electrical connection to the first end section 401 and the second end section 402 of the heating mat 101, the first end sections 401 is connected to the conductive element 105 and the second conductive element 402 is connected to a fur- ther conductive element 105. Each of the plurality of conduc^¬ tive elements 105 is installed in a respective one of the plurality of through-holes 102 in the power transmitting sec^¬ tion 403 of the blade 101. The conductive elements 105 are for example screws that run through the through-holes 102 and further connect and fix the heating mat 101 to the blade 100. The screws are electrically conductive and generate an elec^¬ trical connection to the heating mat 101. The screws may be screwed into the conductive sheet 304 in order to fix the heating mat 101 to the blade 100.

Between the first section 404 and the second section 405 of the heating mat 101 a distance 407 is kept, so that no short circuit is generated. A glass fibre material used as insula- tion material may be interposed within the distance 407.

In a transition section 406, the first section 404 crosses over into the second section 405. Therefore, the heating mat 101 may be folded in order to achieve a change in the run of the heating mat 101. In a further exemplary embodiment, the shape of the heating mat 101 is curved in order to achieve a change in the run of the heating mat 101.

The end sections 401, 402 are located in the power transmit- ting section 403, where the through-holes 102 for providing a power connection are located. Thus, there is no need for electrical wiring along the outer surface 104 of the blade 101. There is only a need to connect the end sections 401, 402 in the region of the root end. In this way, there is less risk of damages of the heating mats 101 due to lightning strikes on the blade.

It should be noted that the term "comprising" does not ex^¬ clude other elements or steps and "a" or "an" does not ex- elude a plurality. Also elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims should not be con^¬ strued as limiting the scope of the claims. List of reference signs:

100 blade

101 heating mat

102 through-hole

103 inner space

104 outer surface

105 conductive element

106 conductor

301 outer section

302 inner section

303 bolt head

304 conductive sheet

305 conductive mesh

401 first end section

402 second end section

403 power transmitting section

404 first section

405 second section

406 transition section

407 distance between first and second section

408 fixing element

Claims

CLAIMS :

1. Blade (100) for a wind turbine, the blade (100) compris^¬ ing

at least one heating mat (101) for generating heat, wherein the heating mat (101) is mounted at an outer surface (104) of the blade (100) ,

at least one through-hole (102) running from an inner space (103) of the blade (100) to the outer surface (104) of the blade (100) , and

at least one conductive element (105), wherein the con^¬ ductive element (105) is electrically coupled to the heating mat (101),

wherein the conductive element (105) is inserted in the through-hole (102) for generating an electric connection between the inner space (103) and the outer surface (104) .

2. Blade (100) according to claim 1,

wherein the heating mat (101) comprises carbon fibres for generating heat.

3. Blade (100) according to claim 1 or 2, further comprising

a root end section with a fixing element for fixing the blade (100) to a hub of the wind turbine,

wherein the through-hole (102) is formed in the root end section .

4. Blade (100) according to one of the claims 1 to 3,

wherein the conductive element (105) comprises an outer section (301), which protrude from the outer surface (104), and an inner section (302), which extends into the inner space (103) ,

wherein a conductor (106) is fixable to the inner sec- tion (302) for supplying power from a power supply unit to the conductive element (105) and wherein the heating mat (101) is electrically connected to the outer section (301).

5. Blade (100) according to one of the claims 1 to 4, wherein the conductive element (105) comprises a conduc^¬ tive bolt,

wherein the conductive bolt is fixed into the through- hole (102) in such a way, that between a bolt head (303) of the conductive bolt and the outer surface (104) the heating mat (101) is clamped for generating an electrically conduc^¬ tive clamping connection.

6. Blade (100) according to claim 5, further comprising

a conductive sheet (304),

wherein the conductive sheet (304) is mounted to the outer surface (104) by the conductive bolt, and

wherein the conductive sheet (304) is electrically cou- pled to the heating mat (101) .

7. Blade (100) according to claim 5 or 6, further comprising

a conductive bushing fixed inside the through-hole

(102),

wherein the conductive bolt is fixed in the conductive bushing .

8. Blade (100) according to one of the claims 1 to 7, fur- ther comprising

a conductive mesh (305) that is interposed between the conductive element (105) and the heating mat (101) .

9. Blade (100) according to one of the claims 1 to 8, fur- ther comprising

an adhesive layer for generating a laminate out of the conductive element (105) and the heating mat (101) .

10. Blade (100) according to one of the claims 1 to 9, fur ther comprising

a cover layer, wherein the cover layer covers the heating mat (101), the conductive element (105) and the outer surface (104) such that a homogeneous outer layer of the blade (100) is formed.

11. Blade (100) according to one of the claims 1 to 10,

wherein the heating mat (101) comprises a first end sec^¬ tion (401) and a second end section (402), wherein the second end section (402) defines an opposite end section of the heating mat (101) in a longitudinal direction of the heating mat (101) with respect to the first end section (401),

wherein the blade (100) further comprises

a power transmitting section (403) located on the outer surface (104) ,

wherein the power transmitting section (403) comprises the through-hole (102) and the conductive element (105) for supplying power to the heating mat (101), wherein the first end section (401) and the second end section (402) are lo^¬ cated inside the power transmitting section (403) and are electrically connected to the conductive element (105),

wherein the heating mat (101) comprises a first section

(404) running from the first end section (401) to a region outside of the power transmitting section (403) and wherein the heating mat (101) comprises a second section (405) run^¬ ning from the region outside of the power transmitting sec- tion (403) to the second end section (402) inside the power transmitting section (403) .

12. Method of manufacturing a blade (100) with a heating system for a wind turbine, the method comprising

mounting at an outer surface (104) of the blade (100) at least one heating mat (101) for generating heat,

forming at least one through-hole (102) into the blade (100), wherein the through-hole (102) runs from an inner space (103) of the blade (100) to the outer surface (104) of the blade (100) ,

inserting at least one conductive element (105) in the through-hole (102) for generating an electric connection between the inner space (103) and the outer surface (104), and electrically coupling the conductive element (105) to the heating mat (101) .

13. Method according to claim 12,

wherein the mounting comprises

adding an adhesive to the heating mat (101) and the outer surface (104) for forming a laminate, and

curing the adhesive.