Wind turbine blade with electric heating system

Abstract

A wind turbine blade includes: a suction side shell portion and a pressure side shell portion of an aerodynamic outer shell extending in a longitudinal direction between a root end and a tip end, and extending in a transverse direction between a leading edge and a trailing edge; and an electro-thermal system, the electro-thermal system comprising: a suction side heating layer and a pressure side heating layer, the suction side heating layer and the pressure side heating layer comprising electrically conductive fibers to mitigate icing on the wind turbine blade; the suction side metal lightning protection layer and the pressure side metal lightning protection layer are used for receiving lightning stroke, are arranged outside the heating layer and are overlapped with the heating layer; and a downlead electrically connected to the metal lightning protection layer so as to be able to conduct a lightning current from the metal lightning protection layer to the root of the wind turbine blade wherein the electric heating system comprises at least one equipotential bonding conductor electrically connecting the conductive fibers of the suction side heating layer and the conductive fibers of the pressure side heating layer, therefore, equipotential bonding is formed.

Description

Technical Field

[0001] The present invention relates to a wind turbine blade having an electrothermal system. Background Art

[0002] When a wind turbine operates in cold climates, ice that may accumulate on the wind turbine blades poses challenges to turbine performance. In a first aspect, any icing on the blade surface will disrupt the aerodynamic performance of the blade, which may lead to a reduction in turbine efficiency and / or an increase in the operating noise level. In another aspect, ice that breaks off from the blade surface can pose a falling hazard. In view of this, wind turbine blades in such locations are typically provided with systems for anti-icing and / or de-icing.

[0003] It is known to provide hot air electrothermal systems that operate on the principle of supplying heated air to the interior of the wind turbine blade to raise the surface temperature of the blade above the freezing point. Examples of such hot air electrothermal systems can be seen in U.S. Patent Application Publication No. US2013 / 0106108.

[0004] It is also known to utilize embedded electrical heating systems and mechanical electrothermal systems in the blade. However, including conductive materials in the blade comes with the risk of lightning strikes associated with these conductive materials, especially when the conductive materials are included near the tip of the blade, as this area of the blade is at high risk of lightning strikes. For electrical heating systems, lightning protection measures are required and surface disturbances are reduced to avoid reducing the annual power generation. Therefore, new solutions are needed. Summary of the Invention

[0005] Based on this background, the object of the present disclosure can be regarded as providing a wind turbine blade having an electrothermal system that overcomes or improves at least one of the disadvantages of the prior art or provides a useful alternative.

[0006] One or more of these objects can be achieved by the aspects of the present disclosure described below.

[0007] A first aspect of the present disclosure relates to a wind turbine blade that includes an aerodynamic outer shell forming the outer surface of the wind turbine blade and an electrothermal system for mitigating icing on the wind turbine blade. The aerodynamic outer shell extends in a longitudinal direction between a root end and a tip end and in a transverse direction between a leading edge and a trailing edge. The aerodynamic outer shell includes a suction side outer shell portion, a pressure side outer shell portion, and a longitudinally extending joint line between the suction side outer shell portion and the pressure side outer shell portion. The joint line preferably extends along the leading edge and / or the trailing edge of the aerodynamic outer shell. The electrothermal system includes: · A suction side heating layer forming part of the suction side outer shell portion of the aerodynamic outer shell, the suction side heating layer including conductive fibers disposed at least in a leading edge section of the suction side outer shell portion; · A pressure-side heating layer that forms part of the pressure-side housing portion of the aerodynamic housing, the pressure-side heating layer including conductive fibers disposed at least in the leading-edge section of the pressure-side housing portion; · Preferably, a cable configured to supply power to the suction-side heating layer and the pressure-side heating layer and configured to be connected to a power source, wherein the conductive fibers of the heating layer are preferably configured to provide resistive heating to the outer surface of the wind turbine blade when receiving power from the power source (e.g., via the cable), preferably so as to mitigate, such as melt or prevent, icing on the wind turbine blade; · A suction-side metallic lightning protection layer disposed outside and overlapping the suction-side heating layer and configured to conduct current from a lightning strike; · A pressure-side metallic lightning protection layer disposed outside and overlapping the pressure-side heating layer and configured to conduct current from a lightning strike; and · A down-conductor having a first end configured to be grounded and disposed at the root of the wind turbine blade, the down-conductor being electrically connected to the suction-side metallic lightning protection layer and the pressure-side metallic lightning protection layer, preferably so as to be able to conduct the lightning strike current from the suction-side metallic lightning protection layer and the pressure-side metallic lightning protection layer to the first end of the down-conductor; wherein the leading edge of the suction-side heating layer and the leading edge of the pressure-side heating layer are arranged adjacent to the joint line and separated by a distance transverse to the joint line, and wherein the electrothermal system includes at least one equipotential bonding conductor that electrically connects the conductive fibers of the suction-side heating layer and the pressure-side heating layer so as to form an equipotential bonding of the suction-side heating layer and the pressure-side heating layer.

[0008] During a lightning strike, the lightning current has a very fast rise time, which typically causes a potential difference between the suction-side heating layer and the pressure-side heating layer. Since the heating layers are separated by the joint line, if the potential difference is too large, a flashover event may occur between the heating layers. Advantageously, by including at least one equipotential bonding conductor, this potential difference between the heating layers can be reduced.

[0009] This can provide several advantages. First, the risk of flashover between the heating layers at the leading edge can be reduced. Second, the distance between the heating layers at the leading edge can be narrowed, resulting in increased heat transfer at the leading edge and thus improved ice mitigation ability. Third, the extent of the heating layers can be increased towards the trailing edge to increase the ice mitigation area of the wind turbine blade.

[0010] Additionally or alternatively, a wind turbine blade may include a suction side spar cap and a pressure side spar cap. The spar caps may also be referred to as the main laminates. The spar caps may be integrally incorporated in the respective shell parts or may form part of a spar provided separately (such as a box spar). The spar caps may include conductive fibers or consist mainly of conductive fibers, such as carbon fiber composites, for example in the form of infused and cured carbon fiber sheets or carbon fiber pultrusions. The suction side heating layer may be arranged to at least partially overlap, optionally completely overlap, with the suction side spar cap, and / or the pressure side heating layer may be arranged to at least partially overlap, optionally completely overlap, with the pressure side spar cap. In this context, the overlap is considered perpendicular to the outer surface of the wind turbine blade. In other words, the suction side heating layer and / or the pressure side heating layer may extend between the distance from the bonding line at the leading edge to the respective spar cap and optionally extend beyond the respective spar cap towards the trailing edge. This overlap may increase the potential difference between the heating layers, for example during a lightning strike, but can be mitigated by adding at least one equipotential bonding conductor.

[0011] Therefore, at least one equipotential bonding conductor may form an electrical connection separate from the cable (including any conductors of the cable). Additionally or alternatively, at least one equipotential bonding conductor may be arranged at a distance from the connection between the cable and the root portions of the suction side heating layer and the pressure side heating layer and at a distance from the connection between the cable and the tip portions of the suction side heating layer and the pressure side heating layer.

[0012] Additionally or alternatively, at least one equipotential bonding conductor forms part of a plurality of equipotential bonding conductors distributed in the longitudinal direction between the root portions and the tip portions of the suction side heating layer and the pressure side heating layer.

[0013] Furthermore, the distance in the longitudinal direction between adjacent equipotential bonding conductors among the plurality of equipotential bonding conductors may be at most 20 meters, preferably at most 15 meters, more preferably at most 10 meters, and most preferably at most 5 meters.

[0014] Additionally or alternatively, at least one equipotential bonding conductor may include at least one trailing edge equipotential bonding conductor (or a plurality of trailing edge equipotential bonding conductors) arranged at the trailing edge (for example, in the trailing edge sections of the suction side shell part and the pressure side shell part). Such conductors are abbreviated as TE - EB conductors. For example, the rear part of the aerodynamic shell extends from the spar cap (or the maximum thickness line of the aerodynamic shell) to the trailing edge.

[0015] Additionally, the (one or more) TE-EB conductors may include a suction side conductor and a pressure side conductor. The suction side conductor may be electrically connected to the conductive fibers of the suction side heating layer and may be embedded in the suction side housing portion. The pressure side conductor layer may be electrically connected to the conductive fibers of the pressure side heating layer and may be embedded in the pressure side housing portion. Embedding the conductors may provide an advantageous manufacturing process, where the conductors may be incorporated in the lay-up of other layers of the respective housing portion. The suction side heating layer may be electrically connected to the front portion of the suction side conductor, and the pressure side heating layer may be electrically connected to the front portion of the pressure side conductor. This may be achieved, for example, by laminating a metallic conductive layer adjacent to the respective heating layer, which may provide good electrical contact for the respective heating layer. The conductor (including its front portion) may be spaced apart from the spar cap (and may thus not overlap). In other embodiments, one or both conductors (including their front portions) may at least partially overlap (optionally completely overlap) with the corresponding one or more spar caps. The front portion of the conductor may be the portion arranged closer to the leading edge of the wind turbine blade (but preferably spaced apart from the leading edge of the wind turbine blade), and the rear portion of the conductor may be the portion arranged closer to the trailing edge of the wind turbine blade.

[0016] The suction side conductor and / or the pressure side conductor may be a conductor layer and may be made of a metallic or plastic material. For example, a metal mesh, such as a copper mesh, an aluminum mesh, a steel mesh, or a bronze mesh, or a conductive plastic, for example having inherent conductivity or including carbon black, and may be in the form of strips. Preferably, the suction side conductor and the pressure side conductor are strips of copper mesh.

[0017] Additionally or alternatively, the TE-EB conductor includes a suction side connector portion and a pressure side connector portion arranged to be in electrical contact with the respective conductor (for example, the rear portion of the respective conductor). The connector portions may each include a solid conductive portion, which may be in the form of a relatively thin element, such as a plate or a disc, and may include threaded elements, such as nuts. The solid conductive portion may be embedded within the respective housing portion, for example, on the outer side of the respective conductor. The solid conductive portion may include or be mainly composed of a metal (such as bronze or copper).

[0018] (One or more) TE-EB conductors may further include a bridging device which preferably electrically connects a rear portion of the suction-side conductor and a rear portion of the pressure-side conductor via respective solid connector portions. The bridging device may include a bridging conductor (e.g., a cable) extending from the suction-side connector portion to the pressure-side connector portion. The bridging conductor may be arranged with slack which allows the relatively flexible suction-side and pressure-side of the aerodynamic outer housing to flex in the thickness direction near the trailing edge due to changing air pressure without impairing the function of (one or more) TE-EB conductors. The bridging conductor may be encapsulated in a cavity (e.g., a hole) of a block arranged between the inner sides of the suction-side housing portion and the pressure-side housing portion. The block may advantageously be made of a resilient material, e.g., made of a foam polymer, preferably configured to allow the suction-side and pressure-side of the aerodynamic outer housing to flex in the thickness direction at the trailing edge due to changing air pressure. Additionally or alternatively, the bridging conductor may be connected to respective external solid connector portions. Furthermore, the braid of the cable may be spread over the solid connector portions at both ends of the bridging device to ensure good electrical contact.

[0019] Alternatively, the bridging device may be a bolt. In this case, the rear portions of the suction-side conductor and the pressure-side conductor may extend to a position adjacent to the trailing edge which has a thickness of at most 20 cm, preferably at most 15 cm, more preferably at most 10 cm. The bolt head may be arranged to be in electrical contact with one of the rear portions of the suction-side conductor and the pressure-side conductor, preferably in electrical contact with the connector portion of the rear portion of the respective conductor. The end arranged opposite to the bolt head may be arranged to be in electrical contact with the other of the rear portions of the suction-side conductor and the pressure-side conductor, preferably the connector portion of the rear portion of the respective conductor, which preferably includes a nut for engaging with the end of the bolt and establishing electrical contact.

[0020] Additionally or alternatively, the rear portions of the suction-side conductor and the pressure-side conductor of the (one or more) TE-EP conductors may extend completely to the trailing edge. The connector portion of the suction-side conductor may define the trailing edge of the suction-side conductor. The connector portion of the pressure-side conductor may define the trailing edge of the pressure-side conductor. The connector portion may be of solid conductive material, such as a solid metal plate. The spacer of the bridging device may be clamped between the trailing edge of the suction-side conductor and the trailing edge of the pressure-side conductor. The spacer may be a metal spacer and may thus define the bridging conductor of the bridging device. Additionally or alternatively to the spacer being metal, the bridging conductor of the bridging device may include one or more conductive tabs extending through the suction-side conductor (such as the connector portion of the suction-side conductor), the spacer, and the pressure-side conductor (such as the connector portion of the pressure-side conductor). The suction-side conductor may be embedded in the suction-side housing portion, and the pressure-side conductor may be embedded in the pressure-side housing portion. During the closing of the suction-side housing portion and the pressure-side housing portion, the spacer may be arranged between the suction-side conductor and the pressure-side conductor. Optionally, one or more conductive tabs may be inserted through one or more corresponding holes extending through the suction-side conductor and the pressure-side conductor and optionally through the bridging conductor. These holes may be pre-drilled before the closing of the housing portions, or may be drilled after the closing of the suction-side housing portion and the pressure-side housing portion. In some embodiments, the spacer may be omitted to achieve a thinner trailing edge of the wind turbine blade.

[0021] Additionally or alternatively, at least one equipotential bonding conductor may include at least one leading-edge equipotential bonding conductor (or a plurality of such conductors) arranged at the leading edge (e.g., in the leading-edge sections of the suction housing portion and the pressure housing portion). Such conductors are abbreviated as LE-EB conductors. The LE-EB conductor may be in the form of a strip and may include or consist mainly of conductive material. The conductor material may be a flexible material, such as conductive fibers (e.g., carbon fibers) or a mesh (such as a copper mesh, an aluminum mesh, or a bronze mesh).

[0022] Additionally or alternatively, the electrothermal system may include a first electrically insulating film and an optional second electrically insulating film extending in the longitudinal direction. The first electrically insulating film may be arranged to electrically insulate the leading edge of one of the suction-side heating layer and the pressure-side heating layer. The optional second electrically insulating film may be arranged to electrically insulate the leading edge of the other of the suction-side heating layer and the pressure-side heating layer.

[0023] The first electrically insulating film and the optional second electrically insulating film may include an outer portion, an inner portion, and an intermediate portion connecting the outer portion and the inner portion.

[0024] The outer part may be arranged on the outer side of the corresponding heating layer, the inner part may be arranged on the inner side of the corresponding heating layer, and the intermediate part may be arranged adjacent to the leading edge of the corresponding heating layer. The outer part and / or the inner part may extend a predetermined distance from the leading edge of the corresponding heating layer, for example, a predetermined distance of at least 30 mm, preferably at least 50 mm, more preferably at least 70 mm.

[0025] Preferably, the first electrical insulation film and the optional second electrical insulation film may extend longitudinally to electrically insulate the entire leading edge of the corresponding heating layer from its root end to its tip end.

[0026] The first electrical insulation film and / or the optional second electrical insulation film may comprise an electrically insulating polymer film (such as a PET film) or consist essentially of an electrically insulating polymer film, optionally reinforced with electrically insulating fibers (such as glass fibers).

[0027] In some embodiments, the addition of the first electrical insulation film and / or the optional second electrical insulation film may provide sufficient electrical insulation to reduce the risk of flashover between the heating layers, allowing the omission of equipotential bonding connections of the heating layers.

[0028] Additionally or alternatively, the leading edges of the suction-side heating layer and the pressure-side heating layer may extend substantially in the longitudinal direction. The distance between the leading edges of the suction-side heating layer and the pressure-side heating layer may be substantially constant in the longitudinal direction. The constant distance may simplify the layup of the heating layers. In other embodiments, the distance between the leading edges of the suction-side heating layer and the pressure-side heating layer may vary. Varying the distance may allow the potential difference to be customized for specific positions along the longitudinal length. For example, the distance may vary from a first distance at the root portion of the heating layer to a second distance at the tip portion of the heating layer, and the first distance may be greater than the second distance. The greater separation of the leading edges at the first distance may effectively provide additional insulation to allow a greater potential difference to be generated before a flashover event occurs. Additionally, the distance may vary linearly (e.g., decrease) from the first distance to the second distance in the longitudinal direction.

[0029] Additionally or alternatively, the suction-side heating layer (preferably the conductive fibers of the suction-side heating layer) and / or the suction-side metal lightning protection layer may be embedded in and co-potted with the suction-side housing portion. The pressure-side heating layer (preferably the conductive fibers of the pressure-side heating layer) and / or the pressure-side metal lightning protection layer may be embedded in and co-potted with the pressure-side housing portion.

[0030] Embedding the suction side heating layer and the pressure side heating layer, as well as the suction side metal lightning protection layer and the pressure side metal lightning protection layer into the corresponding housing parts of the aerodynamic housing and co-curing them can provide a smoother outer surface to improve aerodynamic performance, especially when compared to an arrangement where the heating layer and / or the metal lightning protection layer is laminated onto the aerodynamic housing. Additionally, arranging the suction side metal lightning protection layer and the pressure side metal lightning protection layer externally and overlapping them with the suction side heating layer and the pressure side heating layer can reduce the risk of lightning striking the heating layer.

[0031] Additionally or alternatively, the suction side metal lightning protection layer and the pressure side metal lightning protection layer can be configured to function as lightning receivers and / or for potential equalization.

[0032] Additionally or alternatively, the suction side metal lightning protection layer and the pressure side metal lightning protection layer can be a metal mesh, preferably a copper mesh, such as an expanded copper mesh or a perforated copper mesh.

[0033] Additionally or alternatively, the conductive fibers can be carbon fibers. The conductive fibers can be arranged in one or more fiber layers, preferably biaxially. The fiber layers can be non-woven and / or can be arranged at + / - 45 degrees relative to the longitudinal direction.

[0034] Additionally or alternatively, the cable can include a first electrical conductor connected to the root portions of the suction side heating layer and the pressure side heating layer, and a second electrical conductor connected to the tip portions of the suction side heating layer and the pressure side heating layer. The root portions can be arranged towards the root of the wind turbine blade, and the tip portions can be arranged towards the tip of the wind turbine blade.

[0035] In the context of the present disclosure, when two parts are "co-cured", it is to be understood that the two parts are simultaneously cured with resin in the same process. Thus, co-curing two fiber-reinforced parts (such as the suction side heating layer and the pressure side heating layer in the corresponding housing parts of the aerodynamic housing of a wind turbine blade) involves arranging the dry fibers of the two fiber-reinforced parts in a mold, simultaneously injecting resin into them in the same process, and causing or allowing the resin to cure. This is in contrast to the process of joining two separately manufactured parts or laminating one part onto another part.

[0036] Additionally or alternatively, the electrothermal system can include an electrical insulation layer between each of the suction side metal lightning protection layer and the pressure side metal lightning protection layer and the corresponding heating layer. The electrical insulation layer can be configured to prevent lightning from striking the suction side heating layer and the pressure side heating layer, and preferably can be made of polyethylene terephthalate (PET), such as a PET film. The electrical insulation layer can be embedded in the corresponding housing parts of the aerodynamic housing and co-cured with it.

[0037] Interposing an electrically insulating layer between the heating layer and the corresponding metal lightning protection layer reduces the risk of damage to the heating layer during a lightning strike event and also reduces the risk of a short circuit between the heating layer and the corresponding metal lightning protection layer during operation of the electrothermal system.

[0038] The electrically insulating layer can be configured to prevent lightning from flashing to the heating layer by selecting the material of the electrically insulating layer and the positioning of the electrically insulating layer relative to the corresponding heating layer and the corresponding metal lightning protection layer, such that the flashover voltage required for the flash to cross from the end of the metal lightning protection layer to the corresponding end of the heating layer is greater than the breakdown voltage required for the lightning strike to break down the electrically insulating layer. The flashover voltage and the breakdown voltage can be obtained through experiments, for example.

[0039] Additionally, the electrically insulating layer can include a laminated structure that includes a polymer film (such as a PET film) sandwiched between two fiber layers (preferably glass fiber layers). The laminated structure can be prefabricated before casting and curing the suction side heating layer and the pressure side heating layer, the suction side metal lightning protection layer and the pressure side metal lightning protection layer, and optionally the suction side electrically insulating layer and the pressure side electrically insulating layer. The laminated structure can include an adhesive that adhesively bonds the polymer film to the fiber layers. The adhesive is preferably different from the resin used to cure the suction side heating layer and the pressure side heating layer, the suction side metal lightning protection layer and the pressure side metal lightning protection layer, and optionally the suction side electrically insulating layer and the pressure side electrically insulating layer.

[0040] Furthermore, in embodiments where at least one or both of the heating layers extend near the corresponding spar caps (where there is a risk of flashover and / or breakdown between the heating layer and the spar caps), the electrothermal system can advantageously include additional electrically insulating layer(s) between the corresponding spar cap(s) and the heating layer(s). The additional electrically insulating layer(s) can be provided from the same material as the above-described electrically insulating layer and using the same lay-up process.

[0041] Additionally or alternatively, the suction side heating layer and the pressure side heating layer can include a root edge and a tip edge. The suction side metal lightning protection layer and the pressure side metal lightning protection layer can include a root edge and a tip edge. The tip edges of the suction side metal lightning protection layer and the pressure side metal lightning protection layer can be positioned beyond the tip edges of the suction side heating layer and the pressure side heating layer towards the tip of the wind turbine blade and can be arranged to have a longitudinal gap from the tip edges of the corresponding heating layers.

[0042] This can provide the advantage of further reducing the risk of lightning flashing to the suction side heating layer and the pressure side heating layer rather than the corresponding metal lightning protection layers near the tip of the wind turbine blade.

[0043] Additionally or alternatively, the electrical insulation layer may include a root edge, a tip edge, a leading edge, and a trailing edge. The suction side trailing edge and the pressure side trailing edge of the electrical insulation layer may extend beyond the trailing edges of both the suction side heating layer and the pressure side heating layer, for example, further towards the trailing edge.

[0044] The edges of the suction side heating layer and the pressure side heating layer, the suction side metal lightning protection layer and the pressure side metal lightning protection layer, and the electrical insulation layer may be identified as follows. The root edge may be positioned closest to the root, and the tip edge may be positioned closest to the tip. The trailing edge and the trailing edge may extend substantially in the longitudinal direction. The trailing edge may be located in the suction side housing portion and the trailing edge may be located in the pressure side housing portion. Additionally, the suction side trailing edge and the pressure side trailing edge are the outermost longitudinal edges, for example, closest to the trailing edge.

[0045] Additionally, the trailing edge of the suction side electrical insulation layer may extend beyond the line or plane that intersects the trailing edges of the suction side heating layer and the suction side metal lightning protection layer. The trailing edge of the pressure side electrical insulation layer may extend beyond the line or plane that intersects the trailing edges of the pressure side heating layer and the pressure side metal lightning protection layer.

[0046] Additionally or alternatively, the electrothermal system may include a leading edge insulation layer made of an electrically insulating polymeric material (preferably a PET film). The leading edge insulation layer may extend along and overlap with the bonding line at the leading edge. The leading edge insulation layer may extend laterally from the bonding line and overlap with the suction side metal lightning protection layer and the pressure side metal lightning protection layer along the circumference of the suction side housing portion and the pressure side housing portion.

[0047] By including the leading edge insulation layer, the risk of lightning strike breakdown at the bonding line to the end of the heating layer portion near the bonding line is reduced.

[0048] Additionally or alternatively, the suction side heating layer and the pressure side heating layer may include at least two carbon fiber pads adjacent to the bonding line. This can ensure sufficient heat supply at the bonding line to mitigate icing.

[0049] Additionally or alternatively, the aerodynamic housing may include a leading edge protection cap that overlaps with the bonding line and preferably overlaps with the leading edge insulation layer. The leading edge protection cap may have an outer side exposed to the outside of the wind turbine blade and may be configured to provide erosion resistance for the leading edge of the wind turbine blade. The leading edge protection cap may preferably include polyurethane (PUR) or consist mainly of polyurethane (PUR).

[0050] Additionally or alternatively, the electrothermal system may include a first outer layer covering the suction side metal lightning protection layer and the pressure side metal lightning protection layer. The first outer layer may have an inner side covering the suction side metal lightning protection layer and the pressure side metal lightning protection layer. The first outer layer may preferably include a coating, such as a polyurethane (PUR) coating, and / or a covering, such as a polyester-based covering. The first outer layer may preferably be at most 0.8 mm thick, more preferably in the range of 0.1 to 0.4 mm, and even more preferably in the range of 0.2 to 0.3 mm.

[0051] By covering the suction side metal lightning protection layer and the pressure side metal lightning protection layer with the first outer layer, erosion of the suction side metal lightning protection layer and the pressure side metal lightning protection layer can be reduced. Additionally, providing a first outer layer that is thin enough can reduce the risk of lightning striking the surface of the first outer layer rather than passing through the first outer layer to reach the suction side metal lightning protection layer and the pressure side metal lightning protection layer.

[0052] Additionally or alternatively, the first outer layer may have an outer side exposed to the exterior of the wind turbine blade. Optionally, the aerodynamic housing may include a second outer layer disposed on the first outer layer. The second outer layer may have an outer side exposed to the exterior of the wind turbine blade. The second outer layer may be substantially flush with the first outer layer and may be different from the first outer layer. The second outer layer may preferably be a gel coat, preferably a polyester-based gel coat.

[0053] Additionally or alternatively, the second outer layer may not cover at least the suction side metal lightning protection layer and the pressure side metal lightning protection layer, and / or the rest of the aerodynamic housing.

[0054] Additionally or alternatively, the electrothermal system may include a plurality of cable clamping devices, which at least include a first cable clamping device. The plurality of cable clamping devices may electrically connect the cable and the downlead to form an equipotential bonding connection at different longitudinal positions along the longitudinal direction between the root and the tip of the blade.

[0055] The cable clamp can advantageously provide an equipotential bonding connection between the cable and the lightning cable to reduce or avoid any flashover in the case of lightning striking the blade, and thus reduce or even avoid blade damage.

[0056] Additionally or alternatively, the cable includes a shielding layer, and the plurality of cable clamping devices are electrically connected to the shielding layer of the cable.

[0057] Additionally or alternatively, each of the plurality of cable clamping devices may include a housing and a metal clamping portion. Each metal clamping portion may receive and clamp the downlead and the cable, preferably the shielding layer of the cable, to form an equipotential bonding connection. The housing may surround the metal clamping portion so as to electrically insulate the metal clamping portion and the equipotential bonding connection. The housing may include a through hole for accommodating the downlead and the cable. The housing may preferably be made of a polymer such as polyurethane (PUR).

[0058] Additionally or alternatively, the electrothermal system may include several surge protection devices, including one or more first surge protection devices and / or one or more second surge protection devices and / or one or more third surge protection devices. The first surge protection device may be connected to the suction side heating layer, the pressure side heating layer, and the downlead. The second surge protection device may be connected to the suction side heating layer, the pressure side heating layer, the suction side metal lightning protection layer, and the pressure side metal lightning protection layer. The third surge protection device may be connected to the downlead and the cable.

[0059] Additionally or alternatively, the electrothermal system may include several temperature sensors, including at least one external temperature sensor configured to sense the external temperature of the wind turbine blade and / or at least one internal temperature sensor configured to sense the internal temperature of the wind turbine blade.

[0060] Additionally or alternatively, several temperature sensors may be configured to provide temperature signals to a control device that may be arranged in the hub of the wind turbine. The control device may control the power supply to the suction side heating layer and the pressure side heating layer based on the temperature signals from the several temperature sensors in order to mitigate icing on the wind turbine blade. The type of the temperature sensor may be fiber optic.

[0061] Additionally or alternatively, the electrothermal system may include a tip receiver that is arranged at the tip of the wind turbine blade and is configured to conduct current from a lightning strike, and the tip receiver is electrically connected to the downlead.

[0062] A second aspect of the present disclosure relates to a method of manufacturing an aerodynamic outer shell for a wind turbine blade, preferably according to the first aspect of the present disclosure. The method includes the steps of: laying a heating layer including conductive fibers, a metal lightning protection layer, and an electrical insulation layer together with one or more outer shell layers of the aerodynamic outer shell as a dry layer (i.e., a non-cured layer, such as only fibers without resin), and then co-injecting and curing the layers in a single vacuum-assisted resin transfer molding process in order to embed the heating layer, the metal lightning protection layer, and the electrical insulation layer into the aerodynamic outer shell. Preferably, the heating layer, the metal lightning protection layer, and the electrical insulation layer are thus embedded into one of the suction side outer shell portion and the pressure side outer shell portion of the aerodynamic outer shell, and the method is repeated to separately provide the other of the suction side outer shell portion and the pressure side outer shell portion of the aerodynamic outer shell. Then, the suction side outer shell portion and the pressure side outer shell portion may be closed and attached via a joint line that separates the suction side outer shell portion and the pressure side outer shell portion, optionally closed and attached adhesively.

[0063] A third aspect of the present disclosure relates to a method of manufacturing a wind turbine blade, preferably according to the first aspect of the present disclosure. The method includes the following steps: · Providing: o A suction-side housing portion, which includes a suction-side heating layer and a suction-side metal lightning protection layer. The suction-side heating layer has conductive fibers disposed at least in a leading-edge section of the suction-side housing portion. The suction-side metal lightning protection layer is disposed outside and overlaps with the suction-side heating layer, and is configured to conduct current from a lightning strike, and o A pressure-side housing portion, which includes a pressure-side heating layer and a pressure-side metal lightning protection layer. The pressure-side heating layer has conductive fibers disposed at least in a leading-edge section of the pressure-side housing portion. The pressure-side metal lightning protection layer is disposed outside and overlaps with the pressure-side heating layer, and is configured to conduct current from a lightning strike; · Connect a cable to the suction-side heating layer and the pressure-side heating layer. The cable is configured to be connected to a power source. The conductive fibers of the heating layer are configured to provide resistive heating to the outer surface of the wind turbine blade when receiving power from the cable, so as to mitigate, such as melting or preventing, icing on the wind turbine blade; · Connect a down-conductor to the suction-side metal lightning protection layer and the pressure-side metal lightning protection layer, so as to be able to conduct the lightning strike current from the suction-side metal lightning protection layer and the pressure-side metal lightning protection layer to the first end of the down-conductor disposed at the root of the wind turbine blade; · Close the suction-side housing portion and the pressure-side housing portion along a joint line, thereby forming an aerodynamic housing body. The leading edge of the suction-side heating layer and the leading edge of the pressure-side heating layer are arranged adjacent to the joint line and are separated by a distance transversely to the joint line; and · Electrically connect the conductive fibers of the suction-side heating layer and the conductive fibers of the pressure-side heating layer via at least one equipotential bonding conductor, so as to form an equipotential bonding of the suction-side heating layer and the pressure-side heating layer.

[0064] In addition, the suction-side housing portion and the pressure-side housing portion can be provided by the method according to the second aspect of the present disclosure.

[0065] Additionally or alternatively, at least one of the equipotential bonding conductors may include at least one trailing-edge equipotential bonding (TE-EB) conductor, which includes a suction-side conductor electrically connected to the conductive fibers of the suction-side heating layer and a pressure-side conductor electrically connected to the conductive fibers of the pressure-side heating layer. The step of electrically connecting the conductive fibers of the suction-side heating layer and the conductive fibers of the pressure-side heating layer may include: · Preferably, for example, by drilling a hole from the outside of the wind turbine blade, forming a hole (148) passing through the suction-side connector portion (144) of the suction-side conductor and the pressure-side connector portion (144') of the pressure-side conductor; and / or · Preferably, arranging a bridging device (145) (e.g., a bridging conductor of the bridging device) in the hole; and / or · Preferably, the bridging device is electrically connected to the suction - side connector part and the pressure - side connector part (e.g., by applying a conductive paste) so as to establish an equipotential bond between the conductive fibers of the suction - side heating layer and the conductive fibers of the pressure - side heating layer.

[0066] Additionally or alternatively, at least one equipotential bonding conductor may include at least one leading - edge equipotential bond (LE - EB) conductor. The step of electrically connecting the conductive fibers of the suction - side heating layer to the conductive fibers of the pressure - side heating layer may include: · Preferably, at least one recess is formed at the leading edge of the aerodynamic housing, which recess may extend between the leading - edge section of the suction - side housing part and the leading - edge section of the pressure - side housing part; and / or · Preferably, the leading - edge equipotential bond conductor is arranged in at least one recess; and / or · Preferably, the suction - side part of the leading - edge equipotential bond conductor is electrically connected (e.g., by applying a conductive paste) to the conductive fibers of the suction - side heating layer; and / or · Preferably, the pressure - side part of the leading - edge equipotential bond conductor is electrically connected (e.g., by applying a conductive paste) to the conductive fibers of the pressure - side heating layer; and / or · Preferably, the outer surface of the aerodynamic housing is re - established (e.g., by covering the LE - EB conductor with a layer such as a gel coat).

[0067] Throughout the present disclosure, components of a wind turbine blade may be described as having an "edge" or a "part" with relative positioning terms such as "leading edge", "trailing edge", "root", and "tip". It should be understood that the "root edge" of such a component is arranged towards the root end of the wind turbine blade, but not necessarily at the root end of the wind turbine blade. For example, the "trailing edge" of the suction - side heating layer is arranged closer to the trailing edge of the wind turbine blade than the "leading edge" of the suction - side heating layer, but does not necessarily intersect or coincide with the trailing edge of the wind turbine blade.

[0068] Those skilled in the art will recognize that any one or more of the above aspects of the present disclosure and its embodiments may be combined with any one or more of the other aspects of the present disclosure and its embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. The drawings illustrate one way of implementing the invention and should not be construed as limiting other possible embodiments that fall within the scope of the appended claims.

[0070] Figure 1 is a schematic perspective view of a wind turbine.

[0071] Figure 2is a schematic perspective view of a wind turbine blade having a longitudinal leading edge section for a wind turbine as shown in Figure 1 .

[0072] Figure 3 is a schematic longitudinal view of an electrothermal system incorporated in a longitudinal section of a wind turbine blade as shown in Figure 2 .

[0073] Figure 4A is Figure 3 a schematic perspective view of a trailing edge equipotential bonding conductor of the electrothermal system, wherein the outer layer is omitted for visualization purposes.

[0074] Figure 4B is Figure 4A a schematic perspective view of a suction side connector of the trailing edge equipotential bonding conductor of . Additionally, the metallic lightning protection layer and the electrical insulation layer are omitted for visualization purposes.

[0075] Figure 5A is Figure 4A a schematic cross-sectional view of the trailing edge equipotential bonding conductor of .

[0076] Figure 5B is Figure 5A a schematic detailed view of a bridging device of the trailing edge equipotential bonding conductor at the dashed circle labeled "A" in .

[0077] Figures 6A - 6B is a schematic view of another embodiment of the trailing edge equipotential bonding conductor. Only the suction side conductor and the pressure side conductor are shown, while the remaining layers of the wind turbine blade are omitted for visualization purposes.

[0078] Figure 7 is Figure 3 a schematic perspective view of a plurality of leading edge equipotential bonding conductors of the electrothermal system, wherein the outer layer is omitted for visualization purposes.

[0079] Figure 8 is Figure 2 a schematic cross-sectional view of a longitudinal section of the wind turbine blade as shown in .

[0080] Figures 9A to 9C is a schematic view of a cable clamping device. DETAILED DESCRIPTION

[0081] In the following description of the drawings, like reference numerals refer to like elements and thus may not be described for all of the drawings. Additionally, a suffix "'" appended to a reference numeral denotes the pressure side equivalent of that reference numeral. For example, reference numeral 23 denotes a suction side spar cap, while 23' denotes a pressure side spar cap.

[0082] Figure 1 Shows a conventional modern upwind wind turbine 2 according to the so-called "Danish concept", which has a tower 4, a nacelle 6 and a rotor with a substantially horizontal rotor shaft, which may include an inclination of a few degrees. The rotor includes a hub 8 and three blades 10 extending radially from the hub 8, each blade having a blade root 16 closest to the hub and a blade tip 14 furthest from the hub 8.

[0083] Figure 2 Shows a schematic view of an exemplary wind turbine blade 10. The wind turbine blade 10 has the shape of a conventional wind turbine blade with a root end 17 and a tip end 15, and includes a root region 30 closest to the hub, an airfoil or profile region 34 furthest from the hub, and a transition region 32 between the root region 30 and the airfoil region 34. The blade 10 includes a leading edge 18 facing the rotational direction of the blade 10 when the blade is mounted on the hub 8, and a trailing edge 19 facing the opposite direction to the leading edge 18.

[0084] The airfoil region 34 (also referred to as the profile region) has a blade shape that is ideal or nearly ideal for generating lift, while the root region 30 has a substantially circular or elliptical cross-section due to structural considerations, for example, which makes it easier and safer to mount the blade 10 to the hub. The diameter (or chord length) of the root region 30 may be constant along the entire root region 30. The transition region 32 has a transition profile that gradually changes from the circular or elliptical shape of the root region 30 to the airfoil profile of the airfoil region 34. The chord length of the transition region 32 typically increases as the distance r from the hub increases. The airfoil region 34 has an airfoil profile that has a chord extending between the leading edge 18 and the trailing edge 19 of the blade 10. The width of the chord decreases as the distance r from the hub increases.

[0085] The shoulder 38 of the blade 10 is defined as the position where the blade 10 has its maximum chord length. The shoulder 38 is typically located at the boundary between the transition region 32 and the airfoil region 34.

[0086] It should be noted that the chords of the different sections of the blade generally do not lie in a common plane, since the blade can be twisted and / or bent (i.e., pre-bent), and thus a corresponding twisted and / or bent path is provided to the chord plane, which is to compensate for the most common case of the local speed of the blade depending on the radius from the hub.

[0087] The blade 10 is typically made of a suction side housing part 20 and a pressure side housing part 20', which are glued to each other along a bonding line 28 at the leading edge 18 and the trailing edge 19 of the blade to form an aerodynamic outer shell 12 of the wind turbine blade 10.

[0088] Turning to Figure 3 , schematically shows the electrical connection and lamination structure of an electrothermal system 40 incorporated into such an aerodynamic outer shell 12 of the blade 10. AsFigure 2 As shown, the electrothermal system 40 is designed to mitigate (e.g., by preventing or melting) ice formation in the leading edge section 22 of the wind turbine blade.

[0089] As Figure 3 best seen, the electrothermal system 40 includes a suction side heating layer 50 and a pressure side heating layer 50'. In this embodiment, the suction side heating layer 50 and the pressure side heating layer comprise non-woven biaxial carbon fiber mats, which are arranged to extend substantially in the leading edge section 22 ( Figure 2 as shown), and are oriented at + / - 45 degrees relative to the longitudinal direction. However, other arrangements of the suction side heating layer 50 and the pressure side heating layer 50' may also be employed. The suction side heating layer 50 and the pressure side heating layer 50' respectively include root edges 54, 54' and tip edges 54, 54'. As Figure 4A best seen, the suction side heating layer 50 and the pressure side heating layer 50' further respectively include leading edges 52, 52' and trailing edges 53, 53'. Hereinafter, the edges of the suction side heating layer and the pressure side heating layer, the suction side metal lightning protection layer and the pressure side metal lightning protection layer, and the suction side electrical insulation layer and the pressure side electrical insulation layer can be identified as follows. The root side edges and the tip edges extend substantially in a direction transverse to the longitudinal direction (e.g., the chordal direction), while the suction side trailing edge and the pressure side trailing edge and any leading edge extend substantially in the longitudinal direction. The root edge is located closest to the root, and the tip edge is located closest to the tip. The suction side trailing edge is located at the suction side housing portion 20, and the pressure side trailing edge is located at the pressure side housing portion 20'. In addition, the trailing edge is the outermost longitudinal edge, e.g., closest to the trailing edge of the wind turbine blade.

[0090] Returning to Figure 3 , the electrothermal system 40 further includes a suction side metal lightning protection layer 60 and a pressure side metal lightning protection layer 60' configured to conduct current from a lightning strike. In this embodiment, the suction side metal lightning protection layer 60 and the pressure side metal lightning protection layer 60' are in the form of an expanded copper mesh or a perforated copper mesh. The suction side metal lightning protection layer 60 and the pressure side metal lightning protection layer 60 are respectively arranged outside and overlapping the suction side heating layer 50 and the pressure side heating layer 50', and thus reduce the risk of lightning striking the suction side heating layer 50 and the pressure side heating layer 50'. The suction side metal lightning protection layer 60 and the pressure side metal lightning protection layer 60' respectively include root edges 64, 64' and tip edges 65, 65'. As Figure 8 best shown, the suction side metal lightning protection layer 60 and the pressure side metal lightning protection layer 60' further respectively include trailing edges 62, 62'. As Figure 3As best seen, the distal edges 65, 65' of the suction-side metallic lightning protection layer 60 and the pressure-side metallic lightning protection layer 60' are respectively positioned outside the distal edges 55, 55' of the suction-side heating layer 50 and the pressure-side heating layer 50' towards the distal end 15 of the wind turbine blade, and are arranged to have a longitudinal gap with the distal edges 55, 55' of the suction-side heating layer 50 and the pressure-side heating layer 50'.

[0091] The electrothermal system 40 further includes a cable 90, which includes a first power conductor 91 and a second power conductor 92. The first conductor 91 is electrically connected to the root portions of the suction-side heating layer 50 and the pressure-side heating layer 50', and the second power conductor 92 is electrically connected to the distal portions of the suction-side heating layer 50 and the pressure-side heating layer 50'. The root portions are closer to the root of the wind turbine than the distal portions. The root end of the cable 90 is configured to be connected to a power source, which may be located, for example, in the hub 8 or in the blade 10. Thus, the cable 90 can supply power to the suction-side heating layer 50 and the pressure-side heating layer 50'. Therefore, when the conductive carbon fibers of the suction-side heating layer 50 and the pressure-side heating layer 50' receive power from the cable 90, they can provide resistive heating to the outside of the leading edge section 22 of the wind turbine blade 10, and thus mitigate (e.g., by melting or preventing) icing on the wind turbine blade 10.

[0092] The electrothermal system 40 includes a downlead 95, which has a first end 96 arranged at the root of the wind turbine blade 10. The first end 96 is configured for grounding via the downlead of the hub 8. The downlead 95 is electrically connected to the suction-side metallic lightning protection layer 60 and the pressure-side metallic lightning protection layer 60' so as to be able to conduct the lightning strike current from the suction-side metallic lightning protection layer 60 and the pressure-side metallic lightning protection layer 60' to the first end of the downlead 95. The opposite end of the downlead 95 at the distal end 15 of the wind turbine blade 10 is electrically connected to the distal receiver 98 of the electrothermal system 40 configured to conduct the current from the lightning strike at the distal end 15.

[0093] The electric heating system 40 further includes a plurality of equipotential bonding conductors 130, 140 that electrically connect the conductive fibers of the suction-side heating layer 50 and the conductive fibers of the pressure-side heating layer 50' to form an equipotential bonding between the suction-side heating layer 50 and the pressure-side heating layer 50'. Thus, the plurality of equipotential bonding conductors 130, 140 form an electrical connection separate from the cable 90 (including the conductors 91, 92 of the cable). In the present embodiment, the number of equipotential bonding conductors 130, 140 is two. However, in other embodiments, the number of such equipotential bonding conductors may be only a single one, or even more than two. For example, the number may be at least 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, or 25. In addition, the plurality of equipotential bonding conductors may be distributed in the longitudinal direction L between the root edges 54, 54' and the tip edges 55, 55' of the suction-side heating layer 50 and the pressure-side heating layer 50'. The distance in the longitudinal direction L between adjacent equipotential bonding conductors 130, 140 may be at most 20 meters, preferably at most 15 meters, more preferably at most 10 meters, and most preferably at most 5 meters.

[0094] As Figure 4A shown, the leading edge 52 of the suction-side heating layer 50 and the leading edge 52' of the pressure-side heating layer 50' are arranged adjacent to the bonding line 28 and separated by a distance transverse to the bonding line 28. During a lightning strike, if the potential difference between the heating layers 50, 50' becomes too large, a flashover event may occur on the bonding line between the heating layers 50, 50'. In addition, the wind turbine blade includes a suction-side spar cap 23 and a pressure-side spar cap 23'. The spar cap may also be referred to as the main laminate. The spar cap may be integrally bonded in the corresponding housing part or may form part of a separately provided spar (such as a box spar). The spar cap includes conductive fibers or is mainly composed of conductive fibers, such as carbon fiber composites, for example in the form of infused and cured carbon fiber sheets and / or carbon fiber pultrusions. As Figure 4A and 5A seen, the suction-side heating layer 50 completely overlaps the suction-side spar cap 23, and the pressure-side heating layer 50' completely overlaps the pressure-side spar cap 23'. In this context, the overlap is considered perpendicular to the outer surface of the wind turbine blade. In other words, the suction-side heating layer 50 and the pressure-side heating layer 50' extend from the bonding line 28 at the leading edge 18 and extend beyond the corresponding spar caps 23, 23' towards the trailing edge 19. As mentioned above, the electric heating system 40 includes equipotential bonding conductors 130, 140. These may be leading-edge equipotential bonding conductors 130 (abbreviated as LE-EB conductors) and / or trailing-edge equipotential bonding conductors 140 (abbreviated as TE-EB conductors). In Figures 4A - 4B, in 5A - 5B and 6A - 6B, the structural constitution of the TE - EB conductor 140 is shown. The TE - EB conductor 140 is arranged in the trailing edge section of the suction - side housing part 20 and the pressure - side housing part 20' and faces the trailing edge 19. As Figure 4A and 5A best seen in, the TE - EB conductor 140 includes a suction - side conductor 141 and a pressure - side conductor 141'. The suction - side conductor 141 and the pressure - side conductor 141' are respectively embedded in the suction - side housing part 20 and the pressure - side housing part 20'. The suction - side conductor 141 and the pressure - side conductor 141' are mainly composed of expanded copper mesh, but other conductive materials such as bronze or aluminum can also be used. In Figure 7 , the structural constitution of the LE - EB conductor 130 is shown.

[0095] As Figure 4B and 5A best seen in, the suction - side conductor 141 includes a leading - edge part 142, which is electrically connected to the conductive fibers of the suction - side heating layer 50, for example, as adjacent layers in the laminated stack of the suction - side housing part 20'. In this figure, the suction - side conductor 141 (and thus also the pressure - side conductor) including its front part 142 completely overlaps with the suction - side spar cap 23. In other embodiments, the suction - side conductor and the pressure - side conductor (including their front parts) may be at a distance from the spar cap (and thus may not overlap). As can be seen in the figure, the suction - side electrical insulation layer 70 includes a tongue - like part 76 extending towards the trailing edge 19 and partially covers the range of the suction - side conductor 141 towards the trailing edge 19. The suction - side metal lightning - protection layer 60 also includes a tongue - like part 66 extending towards the trailing edge 19 and partially covers the range of the tongue - like part 76 of the suction - side electrical insulation layer 70 towards the trailing edge 19. It is arranged to provide lightning - protection for the suction - side conductor 141. Figure 4B The pressure - side conductor is omitted in the view of, but the arrangement on the pressure - side is similar to that shown on the suction - side.

[0096] Turning to Figure 5B , the TE - EB conductor 140 further includes a suction - side connector part 144 and a pressure - side connector part 144', which are in electrical contact with the rear parts 143, 143' of the corresponding conductors 141, 141'. The connector parts 144, 144' are solid and relatively thin conductive parts, such as plates or disks, which are embedded in the corresponding housing parts 20, 20' and arranged on the outer sides of the rear parts 143, 143' of the corresponding conductors 141, 141'. The solid connector parts 144, 144' are made of copper, but can also be made of other conductive materials such as bronze.

[0097] The TE-EB conductor 140 further includes a bridging device 145 that electrically connects the rear portion 143 of the suction-side conductor 141 and the rear portion 143' of the pressure-side conductor 141' via respective solid connector portions 144, 144'. The bridging device 145 includes a bridging conductor 146 that extends from the suction-side connector portion 144 to the pressure-side connector portion 144'. The bridging conductor 146 is provided in the form of a cable arranged with slack, which allows the relatively flexible suction side and pressure side of the aerodynamic housing to flex in the thickness direction near the trailing edge due to varying air pressure without impairing the function of the TE-EB conductor 140. The cable is encapsulated in a through-hole cavity 148 of a block 147 disposed between the inner sides of the suction-side housing portion 20 and the pressure-side housing portion 20'. The block 147 is made of a resilient material, such as a foam polymer, configured to allow the suction side and pressure side of the aerodynamic housing to flex in the thickness direction at the trailing edge due to varying air pressure. In Figure 5B the illustrated embodiment, the bridging device 145 further includes a suction-side bolt assembly 149 and a pressure-side bolt assembly 149' to form the connection between the connector portions 144, 144 and the bridging conductor 146. In an alternative embodiment, the bolt assemblies may be omitted, and the braid of the cable may be spread over the solid connector portions 144, 144 at the two ends of the bridging device to ensure good electrical contact.

[0098] Alternatively, the bridging conductor 146 may be a bolt (not shown). In this case, the rear portion 143 of the suction-side conductor 141 and the rear portion 143' of the pressure-side conductor 141' extend to a position adjacent to the trailing edge 19, which has a thickness of at most 20 cm, preferably at most 15 cm, more preferably at most 10 cm. The bolt head may be arranged to be in electrical contact with one of the rear portion 143 of the suction-side conductor 141 and the rear portion 143' of the pressure-side conductor 141', preferably in electrical contact with the connector portions 144, 144 of the rear portion of the respective conductor. The end arranged opposite the bolt head may be arranged to be in electrical contact with the other of the rear portion of the suction-side conductor and the rear portion of the pressure-side conductor, preferably the connector portion of the rear portion of the respective conductor, which preferably includes a nut for engaging with the end of the bolt and establishing electrical contact.

[0099] The TE-EB conductors of a wind turbine blade can be assembled as follows. The suction side conductor 141 and the pressure side conductor 141', as well as the suction side connector portion 144 and the pressure side connector portion 144' are embedded in the corresponding housing portions 20, 20'. After the housing portions 20, 20' are closed and bonded along the joint line 28 to form the aerodynamic housing body 12, holes 148 are drilled from the outside of the housing 12 and extend through the connector portions 144, 144'. A bridging conductor 146 (such as a cable) is inserted through the holes and is electrically connected to the suction side connector portion 144 at one end and to the pressure side connector portion 144' at the opposite end, for example by spreading the braid of the cable onto the connector portions 144, 144' and bonding with a conductive adhesive. These steps are then repeated for the remaining TE-EB conductors.

[0100] Go to Figures 6A - 6B , another embodiment of the TE-EB conductor 140 is shown. In this embodiment, the rear portions 143, 143' of the suction side conductor 141 and the pressure side conductor 141' of the TE-EP conductor 140 extend completely to the trailing edge 19 of the wind turbine blade 10. The connector portion 144 of the suction side conductor 141 defines the trailing edge of the suction side conductor 141, which coincides with the trailing edge 19 of the wind turbine blade 10. The connector portion 144' of the pressure side conductor 141 defines the trailing edge of the pressure side conductor 141, which also coincides with the trailing edge 19 of the wind turbine blade 10. The connector portions 144, 144' are solid metal plates, which are embedded together with the suction side conductor 141 and the pressure side conductor 141' in the corresponding suction side housing portion 20 and pressure side housing portion 20'. A spacer 146a of the bridging device 145 is clamped between the trailing edge of the suction side conductor 141 and the trailing edge of the pressure side conductor 141'. The spacer is a metal spacer and thus defines the bridging conductor 146 of the bridging device 145. Additionally, the bridging conductor 146 of the bridging device 145 includes one or more metal tabs 146b (two are shown), and the metal tabs 146b are arranged in corresponding holes 148 that extend through the connector portions 144, 144' of the suction side conductor 141 and the pressure side conductor 141' and the spacer 146a. During the closing of the suction side housing portion 20 and the pressure side housing portion 20', the spacer is arranged between the suction side connector portion 144 and the pressure side connector portion 144'. The holes 148 can be pre-drilled before the housing portions 20, 20' are closed, or can be drilled after the suction side housing portion 20 and the pressure side housing portion 20' are closed.

[0101] The LE-EB conductors 130 of the wind turbine blade are at Figure 7It can be best seen in and assembled as follows. After the housing parts 20, 20' are closed and bonded along the joint line 28 to form the aerodynamic housing body 12, the positions for providing the LE-EB conductors are determined at the leading edge. A recess (not shown, but present below the shown LE-EB conductor 130) is formed at the leading edge, for example, by grinding, to expose the conductive fibers of the suction-side heating layer 50 and the pressure-side heating layer 50'. Strips of conductive material (such as carbon fiber) are arranged in the recess and electrically connected to the exposed fibers of the suction-side heating layer 50 and the pressure-side heating layer 50'. Then the outer surface at the formed recess is re-established so as to maintain the aerodynamic outer surface of the housing parts 20, 20'. Then these steps are repeated for the remaining LE-EB conductors.

[0102] Go to Figure 8 , the electrothermal system 40 includes a suction-side electrical insulation layer 70 and a pressure-side electrical insulation layer 70' configured to prevent lightning strikes from flashing to the corresponding heating layers ( Figure 3 omitted in the figure). The suction-side electrical insulation layer 70 and the pressure-side electrical insulation layer 70' are respectively interposed between the suction-side metal lightning protection layer 60 and the pressure-side metal lightning protection layer 60' and the suction-side heating layer 50 and the pressure-side heating layer 50'. In this embodiment, the suction-side electrical insulation layer 70 and the pressure-side electrical insulation layer 70' are made of a laminated structure that includes a polyethylene terephthalate (PET) film sandwiched between two layers of fiberglass. Other arrangements can also provide sufficient electrical insulation. The suction-side electrical insulation layer 70 and the pressure-side electrical insulation layer 70' respectively include trailing edges 73, 73'. Compared with the corresponding trailing edges 53, 53 of the suction-side heating layer 50 and the pressure-side heating layer 50', the trailing edges 73, 73' of the suction-side electrical insulation layer 70 and the pressure-side electrical insulation layer 70' extend beyond and further towards the trailing edge ( Figure 8 not shown in the figure, but located opposite to the leading edge 18). In particular, the trailing edge 73 of the suction-side electrical insulation layer 70 extends beyond the first plane P1 that intersects the trailing edge 53 of the suction-side heating layer 50 and the trailing edge 62 of the suction-side metal lightning protection layer 60. Correspondingly, the trailing edge 73' of the pressure-side electrical insulation layer 70' extends beyond the second plane P2 that intersects the trailing edge 53' of the pressure-side heating layer 50' and the trailing edge 62' of the pressure-side metal lightning protection layer 60'.

[0103] As Figure 8As best seen, the wind turbine blade includes a suction side electrical insulation film 150 and a pressure side electrical insulation film 150' made of a PET film, which extend longitudinally along substantially the entire longitudinal length of the respective heating layers 50, 50'. The suction side electrical insulation film 150 insulates the leading edge 52 of the suction side heating layer 50, and the pressure side electrical insulation film 150' insulates the leading edge 52' of the pressure side heating layer 50'. The suction side electrical insulation film 150 and the pressure side electrical insulation film 150' each include an outer portion, an inner portion, and an intermediate portion connecting the outer portion and the inner portion. The outer portion is disposed on the outer side of the respective heating layers 50, 50', the inner portion is disposed on the inner side of the respective heating layers 50, 50', and the intermediate portion is disposed adjacent to the leading edges 52, 52' of the respective heating layers 50, 50'. The outer portion and the inner portion extend a predetermined distance, for example a predetermined distance of at least 30 mm, from the leading edges 52, 52' of the respective heating layers 50, 50' towards their trailing edges, such that the suction side electrical insulation film is arranged to electrically insulate the leading edge of the suction side heating layer, and such that the pressure side electrical insulation film is arranged to electrically insulate the leading edge of the pressure side heating layer. Thus, the potential limit before a flashover event occurs between the leading edges 52, 52' can be increased.

[0104] As Figure 3 As best seen, in the present embodiment, the electrothermal system 40 includes three cable clamping devices 100. The cable clamping devices 100 electrically connect the shielding layer (not shown) of the cable 90 to the downlead 95 to form an equipotential bonding connection at different longitudinal positions along the longitudinal direction between the root end 17 and the tip end 15 of the blade 10.

[0105] The electrothermal system 40 further includes four first surge protection devices 110 and a single second surge protection device 111. The four first surge protection devices 110 are electrically connected to the suction side heating layer 50 and the pressure side heating layer 50' and the suction side metal lightning protection layer 60 and the pressure side metal lightning protection layer 60', and are configured to prevent surge currents in the suction side heating layer 50 and the pressure side heating layer 50' when the wind turbine blade 10 is struck by lightning. The single second surge protection device is disposed between the downlead 95 and the shielding layer of the cable 90.

[0106] The electric heating system 40 further includes: an external temperature sensor 121 configured to sense the external temperature of the wind turbine blade 10; and an internal temperature sensor 120 configured to sense the internal temperature of the wind turbine blade 10. In some embodiments, the external temperature sensor 121 may be omitted. The temperature sensors 120, 121 are configured to provide temperature signals to a control device, which may be arranged, for example, in the nacelle 6 or the hub 8 of the wind turbine 2. Such a control device may control the power supply to the suction side heating layer 50 and the pressure side heating layer 50' based on the temperature signals from the temperature sensors 120, 121 in order to mitigate icing on the wind turbine blade. The internal temperature sensor may be fiber optic, while the external temperature sensor may be wireless.

[0107] Figure 8 The arrangement shown in FIG. is obtained by laying the suction side heating layer 50 and the pressure side heating layer 50', the suction side metal lightning protection layer 60 and the pressure side metal lightning protection layer 60', and the suction side electrical insulation layer 70 and the pressure side electrical insulation layer 70' together with the remaining outer layers 24, 24' of the aerodynamic outer shell 12 (such as carbon fiber layers or glass fiber layers and an optional core layer, such as a foam polymer or balsa wood, however some parts, such as the spar caps 23, may be made of pultruded parts such as carbon fiber pultrusions) as dry layers in corresponding suction side shell molds and pressure side shell molds (not shown), and then infusing and curing the layers 50, 60, 70, 24 and the layers 50', 60', 70', 24' in a parallel vacuum assisted resin transfer molding process. Thus, the suction side heating layer 50 and the pressure side heating layer 50', the suction side metal lightning protection layer 60 and the pressure side metal lightning protection layer 60', and the suction side electrical insulation layer 70 and the pressure side electrical insulation layer 70' are embedded in and co-infused with the corresponding suction side shell part 20 and pressure side shell part 20' of the aerodynamic outer shell 12.

[0108] As Figure 8 Best seen in FIG., the aerodynamic outer shell 12 includes a longitudinally extending joint line 28 between the suction side shell part 20 and the pressure side shell part 20'. At the leading edge 18, the joint line 28 separates the suction side heating layer 50 and the pressure side heating layer 50', the suction side metal lightning protection layer 60 and the pressure side metal lightning protection layer 60', and the suction side electrical insulation layer 70 and the pressure side electrical insulation layer 70'. The suction side heating layer 50, the suction side metal lightning protection layer 60 and the suction side electrical insulation layer 70 are embedded in and co-infused with the suction side shell part 20, while the pressure side heating layer 50', the pressure side metal lightning protection layer 60' and the pressure side electrical insulation layer 70' are embedded in and co-infused with the pressure side shell part 20'.

[0109] To electrically insulate the ends of the suction side heating layer 50 and the pressure side heating layer 50' adjacent to the bonding line 28, the electrothermal system 40 includes a leading edge insulating layer 80 made of electrically insulating PET film. As Figure 8 shown, the leading edge insulating layer 80 extends along and overlaps the bonding line 28 at the leading edge 18. The leading edge insulating layer has trailing edges 81 and 81' spaced from the bonding line 28 along the circumference of the aerodynamic housing 12. Thus, as Figure 8 best seen, the leading edge insulating layer 80 extends laterally from the bonding line 28 and overlaps the suction side lightning protection metal layer 60 and the pressure side lightning protection metal layer 60' along the circumference of the aerodynamic housing 12.

[0110] As Figure 8 shown, the aerodynamic housing 12 includes a leading edge protective cap 83 that overlaps the bonding line 28 and the leading edge insulating layer 80. The leading edge protective cap 83 is configured to provide erosion resistance to the leading edge 18 of the wind turbine blade 10 and has an outer side 84 exposed to the outside of the wind turbine blade 10. The leading edge protective cap 83 is mainly composed of polyurethane (PUR). The suction side trailing edge 81 and the pressure side trailing edge 81' of the leading edge insulating layer 80 extend further towards the trailing edge ( Figure 8 omitted above) than the suction side trailing edge and the pressure side trailing edge of the leading edge protective cap 83. Edge sealing material is provided between the respective trailing edges of the leading edge insulating layer 80 and the leading edge protective cap 83 and between the respective trailing edges of the leading edge insulating layer 80 and the leading edge protective cap 83. The edge sealing material is used to smooth the surface transition between the layers to reduce turbulence.

[0111] The electrothermal system 40 further includes a first outer layer 85 that covers the suction side lightning protection metal layer 60 and the pressure side lightning protection metal layer 60'. The first outer layer 85 has an inner side 87 that faces and covers the suction side lightning protection metal layer 60 and the pressure side lightning protection metal layer 60', and has an outer side 86 that is partially exposed to the outside of the wind turbine blade 10 and is partially covered by the leading edge protective cap 83. The first outer layer is a polyurethane (PUR) coating and is relatively thin, with a thickness in the range of 0.2 - 0.3 mm.

[0112] The aerodynamic housing 12 includes a second outer layer 88 that has an outer side 89 exposed to the outside of the wind turbine blade 10. The second outer layer 88 is substantially flush with the first outer layer 85. The second outer layer 88 does not cover the suction side lightning protection metal layer 60 and the pressure side lightning protection metal layer 60', but instead covers the remaining exposed portions of the aerodynamic housing 12. The second outer layer 88 is formed of a material different from the first outer layer 85. In this embodiment, the second outer layer 88 is a polyester-based gel coat.

[0113] As Figures 9A - 9CAs best seen, each cable clamping device 100 includes a polymer housing 101 and a metal clamping portion 102. The metal clamping portion 102 receives and clamps the shield layers of the down conductor 95 and the power conductors 91, 92 of the cable 90 to form an equipotential bonding connection. The housing 101 surrounds the metal clamping portion 101 so as to electrically insulate the metal clamping portion 101 from the equipotential bonding connection. As Figure 9C As best seen, the housing 101 includes four through holes 103 to accommodate the down conductor 95 and the power conductors 91, 92. In other embodiments, the housing 101 and the metal clamping portion 102 may include three or even two through holes, such as when the electrothermal system includes a single down conductor 95 and a single cable 90.

[0114] List of reference signs 2 Wind turbine 4 Tower 6 Nacelle 8 Hub 10 Blade 12 Housing 14 Blade tip 15 Tip end 16 Blade root 17 Root end 18 Leading edge 19 Trailing edge 20 Suction side housing part 22 Leading edge section 23 Spar cap 24 Housing layer 25 Trailing edge section 20' Pressure side housing part 22' Leading edge section 23' Spar cap 24' Housing layer 25' Trailing edge section 28 Bonding wire 30 Root region 32 Transition region 34 Airfoil region 36 Tip region 38 Shoulder 40 Electrothermal system 50 Suction side heating layer 52 Leading edge 53 Trailing edge 54 Root edge 55 Tip edge 50' Pressure side heating layer 52' Leading edge 53' Trailing edge 54' Root edge 55' Tip edge 60 Suction side metal lightning protection layer 63 Trailing edge 64 Root edge 65 Tip edge 66 Tongue part 60' Pressure side metal lightning protection layer 63' Trailing edge 64' Root edge 65' Tip edge 70 Suction side electrical insulation layer 73 Trailing edge 76 Tongue part 70' Pressure side electrical insulation layer 73' Trailing edge 80 Leading edge insulation layer 81 Suction side trailing edge 81' Pressure side trailing edge 83 Leading edge protection cap 84 Outer side 85 First outer layer 86 Outer side 87 Inner side 88 Second outer layer 89 Outer side 90 Power cable 91 First power conductor 92 Second power conductor 95 Downlead 96 First end 98 Tip receiver 100 Cable clamping device 101 Housing part 102 Metal clamping part 103 Through hole 110 First surge protection device 111 Second surge protection device 112 Third surge protection device 120 Internal temperature sensor 121 External temperature sensor 130 LE-EB conductor 140 TE-EB conductor 141 Suction side conductor 142 Front part 143 Rear part 144 Connector part 141' Pressure side conductor 142' front part 143' rear part 144' connector part 145 bridging device 146 bridging conductor 146a spacer 146b tab 147 block 148 through-hole 149 suction-side bolt assembly 149' pressure-side bolt assembly 150 suction-side electrical insulation film 150' pressure-side electrical insulation film D distance L longitudinal direction P1 first plane P2 second plane

Claims

1. A wind turbine blade (10), comprising: - An aerodynamic outer shell (12) extending in a longitudinal direction (L) between a root end (17) and a tip end (15), and extending in a transverse direction between a leading edge (18) and a trailing edge (19), the aerodynamic outer shell including a suction side shell portion (20), a pressure side shell portion (20'), and a longitudinally extending joint line (28) between the suction side shell portion and the pressure side shell portion, and - An electrothermal system (40) for mitigating icing on the wind turbine blade, the electrothermal system including: - A suction side heating layer (50) forming part of the suction side shell portion of the aerodynamic outer shell, the suction side heating layer including conductive fibers disposed at least in a leading edge section (22) of the suction side shell portion; - A pressure side heating layer (50') forming part of the pressure side shell portion of the aerodynamic outer shell, the pressure side heating layer including conductive fibers disposed at least in a leading edge section (22') of the pressure side shell portion; - A cable (90) configured to supply power to the suction side heating layer and the pressure side heating layer and configured to be connected to a power source, wherein the conductive fibers of the heating layer are configured to provide resistive heating to the outer surface of the wind turbine blade when receiving power from the cable; - A suction side metal lightning protection layer (60) disposed outside and overlapping with the suction side heating layer and configured to conduct current from a lightning strike; - A pressure side metal lightning protection layer (60') disposed outside and overlapping with the pressure side heating layer and configured to conduct current from a lightning strike; and - A down conductor (95) having a first end (96) configured to be grounded and disposed at the root of the wind turbine blade, the down conductor being electrically connected to the suction side metal lightning protection layer and the pressure side metal lightning protection layer so as to be able to conduct lightning strike current from the suction side metal lightning protection layer and the pressure side metal lightning protection layer to the first end of the down conductor; wherein a leading edge (52) of the suction side heating layer and a leading edge (52') of the pressure side heating layer are arranged adjacent to the joint line and separated by a distance (D) transverse to the joint line, and wherein the electrothermal system includes at least one equipotential bonding conductor (130, 140) that electrically connects the conductive fibers of the suction side heating layer and the conductive fibers of the pressure side heating layer to form an equipotential bonding of the suction side heating layer and the pressure side heating layer.

2. The wind turbine blade according to the preceding claim, wherein the suction side shell part includes a suction side spar cap (23), and the pressure side shell part includes a pressure side spar cap (23'), the suction side spar cap and the pressure side spar cap include conductive fibers, wherein the suction side heating layer is arranged to at least partially overlap the conductive fibers of the suction side spar cap, and / or the pressure side heating layer is arranged to at least partially overlap the conductive fibers of the pressure side spar cap.

3. The wind turbine blade according to any one of the preceding claims, wherein the at least one equipotential bonding conductor forms part of a plurality of equipotential bonding conductors distributed along the longitudinal direction, and the distance along the longitudinal direction between adjacent equipotential bonding conductors in the plurality of equipotential bonding conductors is at most 20 meters.

4. The wind turbine blade according to any one of the preceding claims, wherein the at least one equipotential bonding conductor may include at least one trailing edge equipotential bonding (TE-EB) conductor (140) arranged in the trailing edge sections (25, 25') of the suction side shell part and the pressure side shell part.

5. The wind turbine blade according to claim 4, wherein the at least one TE-EB conductor includes a suction side conductor (141), a pressure side conductor (141'), and a bridging device (145), wherein the front part (142) of the suction side conductor is electrically connected to the conductive fibers of the suction side heating layer, and wherein the front part (142') of the pressure side conductor is electrically connected to the conductive fibers of the pressure side heating layer, and wherein the bridging device forms an electrical contact between the rear part (143) of the suction side conductor and the rear part (143') of the pressure side conductor.

6. The wind turbine blade according to claim 5, wherein the TE-EB conductor includes a suction side connector part (144) and a pressure side connector part (144') arranged to be in electrical contact with the respective conductors, and wherein the bridging device forms the electrical contact via the suction side connector part and the pressure side connector part.

7. The wind turbine blade according to any one of claims 5 to 6, wherein the suction side conductor is embedded in the suction side shell part, and wherein the pressure side conductor is embedded in the pressure side shell part.

8. The wind turbine blade according to any one of claims 5 to 7, wherein the bridging device includes a bridging conductor (146), the bridging conductor extending from the suction side conductor, preferably the suction side connector part, to the pressure side conductor, preferably the pressure side connector part, and wherein the bridging conductor is arranged to have a slack.

9. The wind turbine blade according to claim 8, wherein the bridging device comprises a holding member (147) arranged between the inner sides of the suction side housing part and the pressure side housing part, and wherein the bridging conductor extends through a cavity, such as a hole, of the holding member and is arranged in the cavity of the holding member with slack, wherein the holding member comprises an elastically resilient material configured to allow the suction side and the pressure side of the aerodynamic outer shell to flex in the thickness direction at the trailing edge due to air pressure changes.

10. The wind turbine blade according to any one of the preceding claims, wherein the at least one equipotential bonding conductor comprises at least one leading edge equipotential bonding (LE-EB) conductor (130) arranged in a leading edge section of the suction housing part and the pressure housing part.

11. The wind turbine blade according to any one of the preceding claims, wherein the distance between the leading edges of the suction side heating layer and the pressure side heating layer varies along the longitudinal direction from a first distance at the root edge (54, 54') of the heating layer to a second distance at the tip edge (55, 55') of the heating layer, the first distance being greater than the second distance.

12. The wind turbine blade according to any one of the preceding claims, wherein the electrothermal system comprises a suction side electrical insulation film (150) and / or a pressure side electrical insulation film (150') extending along the longitudinal direction, each of the suction side electrical insulation film and the pressure side electrical insulation film comprising an outer part, an inner part, and an intermediate part connecting the outer part and the inner part, wherein the outer part is arranged on the outer side of the corresponding heating layer, the inner part is arranged on the inner side of the corresponding heating layer, and the intermediate part is arranged adjacent to the leading edge of the corresponding heating layer, the outer part and / or the inner part extending a predetermined distance, such as a predetermined distance of at least 30 mm, from the leading edge of the corresponding heating layer towards its trailing edge, such that the suction side electrical insulation film is arranged to electrically insulate the leading edge of the suction side heating layer, and such that the pressure side electrical insulation film is arranged to electrically insulate the leading edge of the pressure side heating layer.

13. A method of manufacturing a wind turbine blade (10) according to any one of the preceding claims, comprising the following steps: - Providing: o A suction side housing part (20) comprising a suction side heating layer (50) and a suction side metallic lightning protection layer (60), the suction side heating layer having conductive fibers arranged at least in a leading edge section (22) of the suction side housing part, wherein the suction side metallic lightning protection layer is arranged outside and overlapping the suction side heating layer and is configured to conduct current from a lightning strike, and o The pressure-side housing part (20'), which includes a pressure-side heating layer (50') and a pressure-side metal lightning protection layer (60'), wherein the pressure-side heating layer (50') has conductive fibers disposed at least in the leading edge section (22') of the pressure-side housing part, and wherein the pressure-side metal lightning protection layer (60') is disposed outside and overlaps with the pressure-side heating layer, and is configured to conduct the current from a lightning strike; - Connect a cable (90) to the suction-side heating layer and the pressure-side heating layer, the cable being configured to be connected to a power source, wherein the conductive fibers of the heating layer are configured to provide resistive heating to the outer surface of the wind turbine blade when receiving power from the cable, so as to mitigate, such as melting or preventing, icing on the wind turbine blade; - Connect a down-conductor (95) to the suction-side metal lightning protection layer and the pressure-side metal lightning protection layer, so as to be able to conduct the lightning strike current from the suction-side metal lightning protection layer and the pressure-side metal lightning protection layer to the first end of the down-conductor disposed at the root of the wind turbine blade; - Close the suction-side housing part and the pressure-side housing part along the joint line (28), thereby forming an aerodynamic housing body (12), wherein the leading edge (52) of the suction-side heating layer and the leading edge (52') of the pressure-side heating layer are arranged adjacent to the joint line and are separated by a distance (D) transversely to the joint line; And - Electrically connect the conductive fibers of the suction-side heating layer and the conductive fibers of the pressure-side heating layer via at least one equipotential bonding conductor (130, 140), so as to form an equipotential bonding of the suction-side heating layer and the pressure-side heating layer.

14. The method according to claim 13, wherein the at least one equipotential bonding conductor includes at least one trailing edge equipotential bonding (TE-EB) conductor (140), the trailing edge equipotential bonding (TE-EB) conductor (140) includes a suction-side conductor (141) electrically connected to the conductive fibers of the suction-side heating layer, and a pressure-side conductor (141') electrically connected to the conductive fibers of the pressure-side heating layer, and wherein the step of electrically connecting the conductive fibers of the suction-side heating layer and the conductive fibers of the pressure-side heating layer includes: - Form a hole (148) passing through the suction-side connector part (144) of the suction-side conductor and the pressure-side connector part (144') of the pressure-side conductor, for example, by drilling from the outside of the wind turbine blade; - Dispose a bridging device (145) in the hole; And - Electrically connect the bridging device to the suction-side connector part and the pressure-side connector part, so as to establish an equipotential bonding between the conductive fibers of the suction-side heating layer and the conductive fibers of the pressure-side heating layer.

15. The method according to any one of claims 13 to 14, wherein the at least one equipotential bonding conductor comprises at least one leading edge equipotential bonding (LE-EB) conductor (130), and wherein the step of electrically connecting the conductive fibers of the suction side heating layer and the conductive fibers of the pressure side heating layer comprises: - forming at least one recess at the leading edge of the aerodynamic housing, the recess extending between the leading edge section of the suction side housing part and the leading edge section of the pressure side housing part; - arranging the leading edge equipotential bonding conductor in the recess; - electrically connecting the suction side part of the leading edge equipotential bonding conductor to the conductive fibers of the suction side heating layer; - electrically connecting the pressure side part of the leading edge equipotential bonding conductor to the conductive fibers of the pressure side heating layer; and - preferably, re-establishing the outer surface of the aerodynamic housing.

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