Insulated lightning transmission system for wind turbine blade

Abstract

A wind turbine blade comprises a lightning transmission system for transmitting lightning current through the wind turbine blade (100). The lightning transmission system comprises one or more lightning arresters (20), a downlead (1) electrically connected to each of the one or more lightning arresters (20) and extending along an interior of the wind turbine blade (100), and a first conductor element (4) proximate a base portion (6) of the wind turbine blade (100). The first conductor element (4) is electrically connected to the downlead (1) and extends through the surface of the blade (100) between the interior and the exterior of the blade wall (10). The first conductor element (4) comprises an electrical insulation element (45) which configures the first conductor element (4) to be electrically insulated from the blade wall (10). The dielectric strength of the electrical insulation element (45) is greater than the dielectric strength of the blade wall (10) at a location through which the first conductor element (4) extends.

Description

Technical Field

[0001] The present invention relates to the field of wind turbine blades, in particular to a blade comprising a lightning transmission system, a wind turbine comprising such a blade, a method of manufacturing a wind turbine, and a method of generating electricity using a wind turbine. Background Art

[0002] Given their height and the fact that they are typically placed in open areas where no other elements can act as lightning receptors, wind turbines are exposed to lightning strikes. Therefore, it is common practice to install a lightning transmission system (LTS) on wind turbines. Since the highest point of a wind turbine is always one of the blades, LTSs are provided on the blades. These systems are designed to guide lightning strikes through the wind turbine along a controlled path that avoids damage to the turbine's electronic components.

[0003] A typical wind turbine LTS includes at least one receiving device on the outer side of the blade, which captures the lightning. The lightning current is then directed to the base of the blade using a down conductor, which is usually placed inside the blade. The receiving device extends through the blade to the inner side of the blade to be connected to the down conductor. To prevent the lightning current from flowing through the electronic components inside the turbine's nacelle, the lightning current is directed again through the blade to the outside, close to the base of the blade, but before reaching the base of the blade where the bearings and other sensitive components are located. On the outer side, another conductor element acts as a transmitter towards one of many possible systems that allow the lightning current to be provided to a grounded element outside the nacelle. Since the nacelle is electrically grounded, the lightning can be effectively transmitted to the earth without affecting the internal components of the wind turbine.

[0004] To pass the lightning current through the blade, a metal conductor, such as a screw, is provided that passes through the blade to form an electrical connection between the down conductor on the inside of the blade and an external component of the LTS, which passes through or is on the outside of the blade. When the base of the blade consists of a conductive material or a water-absorbing material such as wood or wood fiber, the voltage between the metal conductor and the base may exceed the breakdown voltage, and the current may jump from the metal conductor to the base of the blade, causing an undesirable path for the lightning and damaging the turbine's electronic components or any structural components of the blade or turbine. To overcome this problem, turbine blades that include such LTSs are made entirely of non-conductive elements, such as PET. In most cases, this insulates the blade's base from the metal conductor and allows the lightning to be transmitted without reaching sensitive wind turbine components (motor, bearings, moving elements, inserts for securing the blade to the turbine's rotor, electronics, etc.). However, this limits the types of materials that can be used for the base of the blade and does not address the problem of blades that have already been manufactured or are in use that contain conductive elements or wood or wood fiber or blades made of non-conductive materials such as PET (where the thickness of the non-conductive material does not provide sufficient dielectric strength). Furthermore, there is still a breakdown voltage through the blade towards the base of the blade via the metal conductor.

[0005] Furthermore, a significant portion of wind turbine blades are already constructed in part from wood or other water-absorbing materials, such as wood fiber. While wood is a poor conductor, in humid environments, moisture is absorbed by the wood and increases its conductivity. Similar increases in conductivity have been observed using other water-absorbing materials in humid environments. This increased conductivity increases the likelihood that lightning current will flow through the metal screws and toward the base of the blade, ultimately passing to the turbine's bearings and electronic components and damaging or destroying them. Current solutions for these types of blades involve replacing the wood in new designs with plastic materials, such as PET, or any other non-conductive material, which imposes structural constraints on the blades or at least limits the options for blade materials.

[0006] Although there have been several improvements in lightning transmission systems that extend through the surface of blades to conduct lightning to the ground, these improvements focus on improving the transmission of lightning current from the outside of the blade to grounded elements (such as the nacelle) by reducing the breakdown voltage. In other words, they focus on improving the transmitter. However, they do not consider the safe transmission of lightning current through the blade.

[0007] Therefore, there is a need to provide a wind turbine blade including an improved lightning transmission system, wherein the lightning current is transmitted through the blade without affecting the structure of the blade, which can increase the breakdown voltage of the base of the blade so that various elements of the wind turbine (such as structural elements and electronic components) are not damaged by lightning. Summary of the Invention

[0008] According to a first aspect of the present invention, there is provided a wind turbine blade comprising a lightning transmission system for transmitting lightning current through the wind turbine blade, the lightning transmission system comprising one or more lightning receptors, a down conductor electrically connected to each of the one or more lightning receptors and extending along an interior of the wind turbine blade, and a first conductor element proximate a base portion of the wind turbine blade, the first conductor element electrically connected to the down conductor and extending through a surface of the blade between an interior and an exterior of the surface of the blade, wherein the first conductor element comprises an electrical insulation element that configures the first conductor element to be electrically insulated from the blade; wherein a dielectric strength of the electrical insulation element is greater than a dielectric strength of the blade at a location through which the first conductor element extends.

[0009] According to a second aspect of the present invention, there is provided a wind turbine comprising one or more wind turbine blades according to the first aspect.

[0010] According to a third aspect of the present invention, there is provided a method of attaching a lightning transmission system to a wind turbine blade, comprising:

[0011] a) providing wind turbine blades;

[0012] b) providing a lightning transmission system for a wind turbine blade, the lightning transmission system comprising a first conductor element, the first conductor element comprising an electrically insulating element;

[0013] c) Mounting the lightning transmission system to the wind turbine blade, comprising extending a first conductor element through the surface of the blade between an inner portion and an outer portion of the surface of the blade.

[0014] According to a fourth aspect of the present invention, there is provided a method of generating electrical power using a wind turbine according to the second aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to achieve a better understanding of the present disclosure and to show how the same may be practiced, reference will now be made, by way of example only, to the accompanying drawings, in which:

[0016] Figure 1 Schematic diagram showing a lightning transmission system in a wind turbine blade according to the prior art.

[0017] Figure 2A A schematic cross-sectional view of a typical lightning transmission system according to the prior art is shown.

[0018] Figure 2B Show Figure 2A Schematic cross-sectional view of a lightning transmission system illustrating possible undesired paths of lightning current.

[0019] Figure 3 A schematic cross-sectional view of a lightning transmission system according to one or more embodiments is shown.

[0020] Figure 4A A schematic cross-sectional view of a lightning transmission system according to one or more embodiments is shown.

[0021] Figure 4B A schematic cross-sectional view of a lightning transmission system according to one or more embodiments is shown.

[0022] Figure 5 A close-up perspective view of the inside of a blade including a lightning transmission system according to one or more embodiments is shown.

[0023] Figure 6 A cross-sectional side view of a blade including a lightning transmission system according to one or more embodiments is shown.

[0024] Figure 7 A cross-sectional view of a blade including a lightning transmission system according to one or more embodiments is shown.

[0025] Figure 8 A schematic diagram illustrating a wind turbine according to one or more embodiments is shown.

[0026] Figure 9 A cross-sectional view of a wind turbine is shown according to one or more embodiments.

[0027] Figure 10 A cross-sectional view of a wind turbine is shown according to one or more embodiments.

[0028] Figure 11 A schematic diagram illustrating a method according to one or more embodiments is shown. DETAILED DESCRIPTION

[0029] It will be appreciated that the apparatus described herein is also suitable for dissipating static electricity buildup on turbine blades by the same process as described with respect to lightning strikes.

[0030] As used herein, the term "creepage distance" may be understood to mean the shortest distance between two conducting elements measured along the surface of an insulator extending between the two conducting elements. The term "creepage" may refer to the flow of current between two conducting elements along the surface of an insulator.

[0031] As used herein, the term "air distance" may be understood to mean the shortest distance between two conducting elements through air.

[0032] A first aspect of the present invention relates to a wind turbine blade comprising a lightning transmission system (LTS) designed to transmit lightning current through the wind turbine blade. The LTS comprises one or more lightning receptors, a down conductor electrically connected to each of the one or more lightning receptors and extending along an interior of the wind turbine blade, and a first conductor element proximate a base portion of the wind turbine blade, the first conductor element electrically connected to the down conductor and extending through the blade wall between an interior surface and an exterior surface of the blade wall. The first conductor element comprises an electrically insulating element that insulates the first conductor element from the blade. The dielectric strength of the insulating element is higher than the dielectric strength of the blade at the location through which the first conductor element extends. Figure 1 A schematic diagram of a lightning transmission system in a wind turbine blade according to the prior art is shown. A wind turbine blade 100 includes a base 110 that allows the turbine blade 100 to be secured to a wind turbine, for example, to a rotor of the wind turbine. The base 110 is provided at a proximal end of a proximal portion of the blade 100, opposite a distal tip of the blade 100 at a distal end of a distal portion of the blade 100.

[0033] The breakdown voltage of any undesired path for current from the first conductor element through the electrically insulating element to the base of the blade (e.g. path L3) is preferably equal to or higher than the breakdown voltage of any creepage or clearance path through the inner or outer surface of the blade wall 10 to the base portion of the blade (e.g. path L2).

[0034] When the blade is mounted on a turbine and the desired path for the current to the ground also has a breakdown voltage, for example where an air gap is provided between the blade and the nacelle and / or a grounding element, the breakdown voltage of any undesired path for the current from the first conductor element through the electrically insulating element to the base portion of the blade is preferably higher than the breakdown voltage along the desired path. This provides a preference for the current to be transferred to the ground along the desired path rather than along an undesired path.

[0035] As a non-limiting disclosure, the basic components of the LTS are now described to aid understanding of the present invention. It should be noted that although throughout the detailed description of the present invention, some elements of the LTS are generally referred to as receivers and transmitters in the sense of downward lightning (from the blade 100 to the earth), the LTS is also designed for upward lightning (from the earth to the blade 100). The LTS typically includes at least one conductive lightning receptor 20 at the distal portion of the blade 100 for receiving lightning current. As is known in the art, the lightning receptor 20 can be a metal rod, a plate or any other conductive element with high conductivity. Several lightning receptors 20 can be provided along the distal portion of the blade 100. Each lightning receptor 20 is electrically connected to the interior of the blade 100 (for example, extending through the surface of the blade 100, or electrically connected to another conductor extending through the surface of the blade 100). The LTS also includes a down conductor 1 on the inner side of the blade 100, which is connected to at least one lightning receptor 20. The down conductor 1 can be a wire or any other conductive material configured to guide lightning along the blade 100 between the distal and proximal portions of the blade 100. The down conductor 1 can be linear, providing a linear path for lightning between the distal and proximal portions, or the down conductor 1 can take any other shape. Finally, the LTS includes a lightning transmitter 30 located on the outer side of the blade 100, near the base 110 (i.e., at the proximal portion of the blade 100), for transmitting lightning current from the down conductor on the inner side of the blade 100 to the outer side of the blade 100. Typically, the down conductor 1 can connect one or more lightning receptors 20 with the lightning transmitter 30, and the lightning transmitter 30 is configured to transmit current to a grounding element of the turbine, for example, via the nacelle of the turbine. To form a connection between the down conductor 1 and the at least one lightning receptor 20 and / or lightning transmitter 30, in the prior art, a metal bolt 4 ( ) is provided that crosses the blade between the inner and outer sides. Figure 1 not shown).

[0036] Figure 2A and Figure 2B A schematic cross-sectional view of a portion of a lightning transmission system extending through a blade according to the prior art is shown, along with possible desired and undesired paths of the lightning current. It can be seen that, in some cases, the metal bolt 4 may not be able to conduct the lightning current to the desired location, but due to breakdown of insulation on the blade surface or inside the blade, it may deflect the lightning current towards the base 110 of the blade, where it may reach one or more sensitive elements, such as the blade's insulating outer layer 15a, which may be made of, for example, fiberglass. The blade 100 comprises a wall 10, which may comprise an inner layer 7 and outer layers 15a, 15b covering the inner layer 7. In the prior art, the inner layer 7 may comprise an insulating material, such as PET, in order to prevent Figure 2B. If the inner layer 7 were to comprise a water-absorbing material (such as wood) within the blade, the lightning current would be more likely to reach the base portion 6 (e.g. a metal base portion) of the base 110 of the blade due to the increased conductivity of the water-absorbing material, especially in a humid environment. The base portion 6 may be the base 110 of the blade, a metal blade root insert, or any other part of the blade that is electrically connected to an element inside or outside the blade, away from which the lightning current should be routed. Figure 2A As shown in FIG, the expected path L1 of the lightning is through the conductor 4 and to the outside of the blade, where it passes to the grounded elements on the turbine and bypasses the base portion 6 and elements such as bearings and electronics. Figure 2B As shown, the lightning current may alternatively take undesirable paths L2, L3, where it is deflected to the base portion 6 through the inner material 7 (path L2) or through the outer layers 15a, 15b of the blade (such as those of a fiber material) (path L3). The present invention is directed to an improved alternative to such LTS systems to avoid such undesirable electrical deflection across the blade surface, regardless of the type of material or materials used to construct the blade. It should be noted that if the electrical connection between the down conductor 1 and the metal bolt 4 is close to the inner surface of the wall 10 of the blade 100, there is a higher probability of creepage occurring along the inner surface of the wall 10 (such as in path L2), which may provide an undesirable path with a lower breakdown voltage for the lightning current. Therefore, the present invention is also directed to reducing the probability of such creepage.

[0037] Figure 3 A schematic cross-sectional view of the proximal end of a wind turbine blade 100 is shown. The wind turbine blade 100 may include Figure 1 The blade 100 comprises a LTS for transmitting lightning current through a wind turbine blade (partially shown at a proximal portion of the blade 100), comprising a first conductor element 4 extending through a surface of the blade 100 between an inner portion and an outer portion of the surface of the blade 100. The first conductor element 4 comprises an electrically insulating element 45 (e.g. an insulating layer) which configures the first conductor element 4 to be electrically insulated from the blade 100. The blade 100 comprises a base portion 6 electrically connected to an electrically sensitive part, which may be a component part of the base 110. Advantageously, this reduces the flow of lightning current from the first conductor element 4 to the base portion 6 (i.e. the portion 6 of the blade 100) by increasing the breakdown voltage between the conductor element 4 and the base portion 6. Figure 2B The possibility of paths L2 and L3) shown in FIG.

[0038] It should be noted that Figure 3The surface cross-section of shows a blade 100 comprising three layers of material, namely an inner layer 7 and two outer layers 15a and 15b, the inner layer 7 comprising or consisting of a conductive material and / or a water-absorbing material such as wood or wood fiber or an insulating material such as PET, and two outer layers 15a and 15b, on the inside and outside of the blade respectively, comprising or consisting of a fibrous material. However, in other embodiments, the blade 100 may comprise any number of layers comprising or consisting of any material. Furthermore, the thickness of each layer may not be uniform along the length of the blade. For example, the thickness of each layer may vary along the blade 100. In some embodiments, the layers 15a, 15b may not be fibrous layers. It should also be noted that the first conductor element 4 is formed by Figure 3 An electrical connection 9a, not shown in detail, is electrically connected to the down conductor 1 on the inside of the blade 100. This connection can be any suitable direct connection, or it can be any suitable indirect connection via one or more connecting elements. Thus, it can be connected in a number of ways, such as via a conductive plate, as described in further detail below. The first conductor element 4 can also be connected to an external element of the LTS on the outside of the blade 100 via an external electrical connection 9b, which, as described for electrical connection 9a, can be a direct or indirect connection. The connections 9a, 9b to the other elements can be provided at distances Da, Db, respectively, from the surface of the blade. The connections 9a, 9b can be provided at different distances Da, Db, or one or both can be provided on the surface of the blade. Providing distances Da and / or Db creates an air gap between the connections 9a and / or 9b and the base portion 6, thereby increasing the breakdown voltage at the electrical connection, which in turn increases the likelihood that the lightning current will take the desired path. Providing the connection at a distance from the blade surface also increases creepage distance.

[0039] Advantageously, the provision of the electrical insulation element 45 increases the likelihood that the lightning current will take the desired route, as the breakdown voltage of the insulation element 45 is higher than the breakdown voltage of the blade at the portion of the blade through which the conductor 4 extends. Since the breakdown voltage between the conductor element 4 and the base portion 6 is provided by the electrical insulation element 45, one or more layers of the blade 100, such as the inner layer 7, can comprise or consist of an electrically conductive and / or water-absorbing material without an increased risk of the lightning current being deviated towards the base portion 6.

[0040] The breakdown voltage of the insulating element 45 may also be greater than the breakdown voltage of lightning propagating from the outside of the blade to the nacelle or grounding element (when installed on a particular turbine), so that current is preferentially transferred along the desired path to the ground rather than to the base portion 6 of the blade. The breakdown voltage of the insulating element 45 may also be equal to or greater than the breakdown voltage of creepage or gap currents traveling along the inner or outer surface of the blade wall 10 to the base portion 6, so that current from the conductor 4 to the base portion within the blade wall 10 does not take precedence over current traveling through the inner or outer surface of the blade wall 10.

[0041] In a preferred embodiment, the increase in breakdown voltage associated with the insulating element 45 (i.e., the increase in breakdown voltage of any electrical path from the conductor 4 through the insulating element 45 through the interior of the blade wall 10 to the base portion 6) is equal to or greater than the breakdown voltage along the creepage and clearance distance from the electrical connection between the down conductor 1 and the conducting element 4 to the base portion 6 and / or between the conductor 4 and a grounded element of the turbine (e.g., the nacelle).

[0042] The first conductor element 4 can be any type of electrical conductor, such as a bolt, a wire, a flat steel bar or a cable. The first conductor element 4 can electrically connect the two conducting elements of the LTS via electrical connections 9a, 9b at their respective ends. In some embodiments, the electrical insulation element 45 can be included along the entire first conductor element 4, while in other embodiments, the electrical insulation element 45 can be included only in some sections of the first conductor element 4 (such as the section extending through the blade 100). It should be noted that in some embodiments, the insulating properties of the electrical insulation element 45 can be different in some sections than in other sections. For example, the thickness of the electrical insulation element 45 can be different in some sections than in other sections. Finally, it should be noted that although in the illustrated embodiment, the first conductor element 4 extends perpendicular to the blade surface, the proposed solution is not limited by the angle made by the first conductor element 4 relative to the inner and / or outer surface of the blade.

[0043] The first conductor element 4 may be electrically insulated from the blade such that the breakdown voltage through the blade 100 to the base portion 6 of the blade 100 is greater than a predetermined threshold voltage. The threshold voltage may be defined by the breakdown voltage of the remaining elements further down the desired electrical path L1 of the LTS, wherein one or more air gaps or one or more other insulating elements are provided along the desired electrical path L1. As an example, a lightning strike received by the lightning receptor 20 will be transferred to the conductive element 4 via the down conductor 1. At the electrical connection, the distance Da provides an increased creepage and clearance distance, which means that the breakdown voltage is relatively high and the lightning current passes through the conductor 4. As the lightning current passes through the blade wall 10 via the conductive element 4, it is also suppressed from flowing directly to the base portion 6 due to the higher breakdown voltage provided by the insulating element 45. Finally, at the connection 9b, the creepage and clearance distance is increased again by a distance Db, such that the lightning current is suppressed from following an undesirable path and is transferred to the conductive element 5 from which it can safely reach the earth. If there is an air gap (such as an air gap) between the conductive element 5 and the earth Figure 7 ), the breakdown voltage of the creepage and clearance distances from connections 9a and 9b should be greater than the total breakdown voltage of those air gaps. Similarly, the total breakdown voltage of any electrical path from the conductive element 4 inside the blade to the base portion 6 (i.e., across the insulating element 45) should be greater than the total breakdown voltage of those air gaps.

[0044] The electrical insulation element 45 may comprise any electrical insulation material, such as plastic, rubber, nylon, PE, and any other suitable material for insulating electrical cables. For example, the first conductor element 4 may be a bolt covered by the electrical insulation element 45, or a coated cable in which the coating acts as the electrical insulation element 45.

[0045] For example, for a given electrical insulation element 45 material with a known breakdown voltage value and other materials 7, 15a, 15b of the blade 100 that form the blade in a path toward the base portion 6 of the blade 100 with other known breakdown voltage values ​​(if insulating), the appropriate thickness of the electrical insulation element 45 can be determined so that the breakdown voltage is above a predetermined threshold. Since the distance covered by the blade's material 7, 15a, 15b along paths L2, L3, and any other possible paths, between the first conductor element 4 and the base portion 6 of the blade 100, is known, the minimum material of the electrical insulation element 45 required to ensure that the breakdown voltage through the LTS along the desired path is lower than the breakdown voltage through such electrical insulation element 45 and the materials in the blade can be calculated, as is known in the art. This also ensures that the lightning current will flow through the LTS system along the desired path, thereby effectively reducing the probability of electrical deviation through the blade 100 to the base portion 6 of the blade 100, which could damage sensitive components, such as the bearings of the blade 100 or any electrical components electrically connected to the blade. It should be noted that different paths through the surface of the blade, including cracks or any other changes in the material 7, 15a, 15b, may be taken into account when calculating the material and dimensions to be used.

[0046] In embodiments where one or more air gaps are provided along the expected path of the lightning current (e.g., with reference to Figure 7 In the embodiment described, it is necessary to ensure that the breakdown voltage of each undesired path is higher than the breakdown voltage of the desired path so that current preferably flows along the desired path. For example, the breakdown voltage of the creepage and clearance paths along the undesired lightning path from connections 9a and 9b should be higher than the breakdown voltage along the desired path. Similarly, the breakdown voltage of the undesired path from conductive element 4 at a point within blade 100 and through insulating element 45 must be higher than the breakdown voltage of the air gap(s) along the desired path from the exterior of the blade to ground.

[0047] In a preferred embodiment, if Figure 3 As shown in FIG, an electrical insulation element 45 is provided at least along the portion of the first conductor element 4 that traverses the surface of the blade 100. Advantageously, this inhibits lightning current from flowing from the first conductor element 4 within the blade 100 due to the increased breakdown voltage provided by the insulation element 45.

[0048] It should be noted that Figure 3A first conductor element 4 is shown in the form of a cable that can be connected to one or more other conductive elements via one or more electrical connections 9a, 9b on the inner and outer sides of the blade, respectively, and the connections 9a, 9b can be provided at distances Da, Db, respectively, from the surface of the blade. However, in other embodiments, the first conductor element 4 can be a bolt or any other conductor element that electrically connects the inner and / or outer surfaces of the blade 100 or conductive elements on the inner and / or outer surfaces of the blade 100. Furthermore, the distances Da, Db can be the same or different, or one or more of the connections 9a, 9b can be provided near the surface of the blade 100, with an intermediate insulating layer provided between the one or more connections 9a, 9b and the surface of the blade 100 to provide a sufficient breakdown voltage between the connections 9a and / or 9b and the surface of the blade 100.

[0049] It should be noted that in some embodiments, the insulating properties of the electrical insulation element 45 may vary along the conductor element 4. For example, the thickness of the electrical insulation element 45 may be different in some sections than in other sections, and / or the electrical insulation element 45 may include or be composed of different materials having different insulating properties along its length.

[0050] In the same reference Figure 3 In another preferred embodiment shown, the first conductor element 4 is electrically connected to one or more other conducting elements via one or more electrical connections 9a, 9b, which are provided at a distance away from the inner and / or outer surface of the blade 100, so that an air gap is provided between the one or more electrical connections 9a, 9b and the surface of the blade 100, thereby increasing the clearance and, in particular, the creepage distance.

[0051] This distance may be configured to provide a breakdown voltage between the respective connection and the base portion 6 that is greater than the breakdown voltage of the desired electrical path (e.g., path L1). Advantageously, this inhibits lightning current from flowing from the electrical connections 9a, 9b to the base portion 6 of the blade by providing a breakdown voltage along an undesired path (e.g., path L2 or L3) towards the base portion 6 of the blade 100 through the air gap and through the layers of the blade 100, wherein this breakdown voltage is higher than the breakdown voltage along the desired electrical path.

[0052] It should also be noted that Figure 3 The first conductor element 4 is shown in the form of a cable comprising in its outermost portion an electrically insulating element 45. However, in other embodiments the first conductor element 4 may be a bolt or any other conductor element extending through the blade surface between the inside and the outside of the blade's surface.

[0053] It will be appreciated that the air gap between the electrical connections 9a, 9b and the blade 100 will depend on the desired breakdown voltage of the electrical path, as well as the material and dimensions of the insulating element 45, and the various elements of the blade 100 and other elements of the lightning transmission system and their configuration. It should be noted that a person skilled in the art may consider other factors, such as the expected humidity of the air in the location of the turbine, to determine the size of the air gap in order to ensure the desired breakdown voltage of the air gap.

[0054] It should be noted that the insulating element 45 can take a variety of forms and shapes. For example, in some embodiments, the insulating element 45 is an insulating layer, such as Figure 3 As shown in . Figure 4A A schematic cross-sectional view of the proximal end of a wind turbine blade 100 is shown, wherein the insulation element 45 comprises a plurality of parts. Figure 4A The wind turbine blade 100 shown in FIG. 1 may include Figure 1 All features of Blade 100 and can also be compared with reference Figure 3 The wind turbine blade 100 described is identical except for the insulation element 45. The same reference numerals are used to indicate the same elements as referenced above. Figure 3 In some embodiments (such as Figure 4A In the embodiment shown in FIG ), the insulating element 45 includes a plurality of inserts 45a, 45b, each made of an insulating material. The inserts 45a and 45b may be, for example, bushings. The inserts 45a, 45b extend through the wall 10 and define a straight-through passage through which the conductor 4 extends. The inserts 45a, 45b completely surround the conductor passing through the wall 10, so that any current passing through the blade wall 10 must pass through the insulating element 45. One or both of the inserts 45a, 45b may include a flange 48 that abuts the interior and exterior surfaces of the blade wall 10, respectively. The electrical connection between the down conductor 1 and the conductor 4 may be provided on the side of the flange 48 opposite the interior surface of the wall 10. The electrical connection between the conductor 4 and the second conductor element 5 may be provided on the side of the flange 48 opposite the exterior surface of the wall 10. Since the electrical connection is provided away from the surface of the blade wall 10, providing such a flange 48 can increase the creepage of the electrical connection and also seal the hole through which the conductor 4 passes through the blade wall 10, thereby preventing water or moisture from entering the blade wall 10, which could otherwise degrade the breakdown voltage along an undesirable path. Furthermore, the flange 48 increases the breakdown voltage of the undesirable direct electrical path from the connections 46, 47 to the base portion 6 because this direct path is through the insulating material of the flange 48, rather than air. It should be noted that any suitable electrical connection can be used between the down conductor 1 and the conductor 4, and between the conductor 4 and the second conducting element 5. For example, as shown in FIG4 , these electrical connections can be formed by bolts 46, 47. In other embodiments, these connections can be formed, for example, by welding.

[0055] Figure 4B A schematic cross-sectional view of the proximal end of a wind turbine blade 100 is shown, wherein the insulation element comprises a single insert 45b. Figure 4A The wind turbine blade 100 shown in FIG. 1 may include Figure 1 All features of Blade 100 and can also be compared with reference Figure 3 The wind turbine blade 100 is identical to that described except for the insulation element 45. In some embodiments (such as Figure 4B In the embodiment shown in ), the insulating element 45 comprises a single insert 45b made of insulating material. The insert 45b can be, for example, a sleeve. The insert 45b extends through the wall 10 and defines a straight-through channel through which the conductor 4 extends. The insert 45b completely surrounds the conductor 4 passing through the wall 10 so that any current passing through the blade wall 10 must pass through the insulating element 45. The insert 45b can include a flange 48 adjacent to the outside of the blade wall 10. The electrical connection between the conductor 4 and the second conductor element 5 can be provided on the side of the flange 48 opposite to the outer surface of the wall 10. Since the electrical connection is provided away from the surface of the blade wall 10, the provision of such a flange 48 can increase the creepage of the electrical connection and prevent the ingress of water or moisture as described above. In addition, the flange 48 increases the breakdown voltage of an undesirable direct electrical path from the connection 47 to the base portion 6 because this direct path is through the insulating material of the flange 48, rather than air. It should be noted that the length of the insert can be longer than the thickness of the blade wall 10 so that the distance Da is maintained between the connection 46 and the inner surface of the blade wall 10, thereby increasing the creepage distance without providing a flange. It should be noted that in some embodiments, the insert 45b can be reversed so that the flange 48 is provided in the inner side of the blade wall 10 near the connection 46.

[0056] Figure 5 A close-up perspective view of an indirect electrical connection 9a of a blade 100 is shown according to one or more embodiments. In the illustrated embodiment, one electrical connection 9a comprises a conductive plate 3 mounted to the interior surface of the blade 100 via one or more electrically insulating mounting elements 2. The conductive plate 3 electrically connects between the down conductor 1 and the first conductor element 4. The conductive plate 3 has an inwardly extending lateral extent relative to the interior surface of the blade 100, such that the connection between the plate 3 and the first conductor element 4 is further away from the interior surface of the blade 100 than the connection between the plate 3 and the down conductor 1, thereby ensuring greater creepage and clearance distances. It should be noted that the connection between the down conductor 1 and the plate 3 at the bolt 31 may also be located further away from the interior surface of the blade 100, as in Figure 6. Additionally, if desired, an insulating layer can be provided behind plate 3, on the interior surface of the blade, to increase the breakdown voltage from bolt 31 to the interior surface of blade 100. In other embodiments, plate 3 can be U-shaped or any other suitable shape, such that bolt 31 is provided at the same distance from the interior surface of blade 100 as bolt 34. It should be noted that in some embodiments, conductive plate 3 can be a strip or other conductive element that connects down conductor 1 and first conductor element 4. Electrical connection 9a can also be mounted to interior surface 15a of blade 100 via one or more insulating mounting elements 2. Mounting elements 2 provide further structural support for electrical connection 9a while maintaining a preferred electrical path by inhibiting current flow through the one or more mounting elements 2 due to their electrical insulation. The mounting elements can be made of any electrically insulating material, such as PET, nylon, or any suitable electrically insulating polymer. In some embodiments, mounting elements 2 may not be provided. It should be understood that electrical connection 9b can be provided using a conductive plate having the features described above for connection 9a, but mounted to the exterior surface of blade wall 10.

[0057] Advantageously, having the electrical connection 9a comprising the conductive plate 3 allows the down conductor 1 and the conducting element 4 to be connected independently of their relative positions. In other words, the plate 3 provides an intermediate electrical connection, which provides further flexibility in the relative positioning of the conducting element 4 and the down conductor 1. The plate 3 also provides increased clearance and creepage distances for the electrical connection to the surface of the blade and to internal parts of the blade, such as the base portion 6. The same conclusions can be drawn for the electrical connection 9b between the conducting element 4 and the conductor element 5 when it is provided at a distance away from the outer surface of the blade, for example as Figure 6 As shown in .

[0058] It should be noted that although Figure 5 The electrical connection 9a includes a conductive plate 3 having the identified shape; however, in other embodiments, the conductive plate 3 may have a different shape. It should also be noted that in the illustrated embodiment, the conductive plate 3 is electrically connected to the down conductor 1 and the first conductor element 4 via bolts 31 and 34. However, as will be appreciated by those skilled in the art, in other embodiments, different types of electrical connectors may be used, such as welded connections, lugs, or any other type of electrical connection. Similarly, the conductive plate 3 is connected to the electrically insulating mounting element 2 via bolts 32, but as with bolts 31 and 34, other connection mechanisms known in the art may be used.

[0059] The electrical connections 9a, 9b may comprise or consist of any suitable metal, such as copper, aluminium, steel or alloys thereof.

[0060] In addition, it should be noted that Figure 5The electrical connection 9a includes two electrically insulating mounting elements 2 extending between the inner layers 15a of the blade 100. In the illustrated embodiment, the mounting elements 2 are straight and perpendicular to the inner surface of the blade 100. However, it should be noted that in some embodiments, only one electrically insulating mounting element 2 is provided, or more than two electrically insulating mounting elements 2 are provided. Furthermore, the electrically insulating mounting elements 2 can have shapes other than those illustrated (such as angled or curved shapes), and their cross-sectional shapes can be oval, square, or any other suitable cross-sectional shape rather than circular. One or more insulating mounting elements 2 can be mounted at different angles relative to the inner surface of the blade 100, or even attached to other surfaces of the blade. One or more electrically insulating mounting elements 2 can be bolted or glued to the blade surface or any other internal portion of the blade. When bolted, the mounting element 2 can be bolted through the entire blade, attached only to the surface, or to one of the layers (such as 15a) that constitute the blade or a lug embedded in the blade.

[0061] The one or more electrically insulating mounting elements 2 can comprise any insulating material, such as plastic, rubber, or nylon. It should be noted that the one or more electrically insulating mounting elements 2 can be constructed entirely of a single insulating material, or can comprise any other insulating or non-insulating material, as long as the electrically insulating mounting element 2 still provides complete electrical insulation between the conductor plate 3 and the blade 100. For example, it can be constructed of a structural material surrounded by an insulating material, such as rubber, that provides structural rigidity to the insulating mounting element 2. The mounting element 2 can include one or more embedded sleeves and / or internal threads to allow for a threaded connection of the plate 3 to the mounting element 2 and / or a threaded connection between the mounting element 2 and the blade 100.

[0062] In another preferred embodiment, the blade 100 comprises an electrically conductive element and / or a water-absorbing material (e.g. the inner layer 7), and the first conductor element 4 traverses the electrically conductive element and / or the water-absorbing material of the blade 100. For example, Figure 3 , the interior layer 7 includes a conductive element and / or water-absorbing material located within the blade, between the fiber layers 15a and 15b, extending along the blade at least at the portion where the first conductor element 4 extends across the surface of the blade 100, and connected to or in contact with the base portion 6 of the blade 100. Since the conductor element 4 includes the insulating element 45, the preferred electrical path L1 is still maintained as the preferred path because the insulating element 45 maintains an increased breakdown voltage between the conductor element 4 and the base portion 6.

[0063] It should be noted that in some other embodiments, the blade 100 may alternatively or additionally include the conductive material and / or the water absorbing material in another element of the blade (such as the other layers 15a, 15b), or any other element of the blade that the conductor element 4 traverses, or any element between the conductor element 4 and the base of the blade 100, or it may even include the entire blade. For example, the conductive material and / or the water absorbing material may be included in the inner surface of the blade. It should also be noted that the conductive material and / or the water absorbing material may not be electrically connected to the base portion 6 of the blade 100, but rather be located between the first conductor element 4 and the base portion 6, thereby reducing the breakdown voltage (which is offset by the increased breakdown voltage provided by the insulating element 45). In addition, although in Figure 5 In the figures, the conductive elements and / or water absorbing material are included in the blade, surrounded by the other layers 15a, 15b, but it should also be noted that the conductive elements and / or water absorbing material may be included in other locations of the blade, or the blade may include only some or no other layers 15a, 15b.

[0064] Advantageously, the first conductor element 4 surrounded by the insulating element 45 also prevents lightning current from being deflected through the conductive elements and / or water absorbing material of the blade 100 towards the base portion 6 of the blade 100. This allows a wider range of materials to be used for the blade 100 without affecting the preferred electrical path of the blade's LTS.

[0065] In another preferred embodiment, blade 100 comprises wood or wood fiber, a water-absorbing material. While wood is non-conductive under normal dry conditions, it becomes conductive when the wood or wood fiber layer becomes moist or damp. The breakdown voltage of blade 100 is reduced because the wood or wood fiber provides an easier path for lightning current to flow in the presence of water. The base portion 6 of the blade is, in turn, electrically connected to sensitive components of the turbine, such as bearings and electronics for converting the blade's motion into electrical power. As such, lightning currents that follow undesirable paths could potentially damage the blade or turbine components, such as blade inserts and electronic components. Therefore, even though the blade comprises wood or wood fiber, the insulating element 45 and air gaps Da and Db provide a breakdown voltage for the undesirable paths.

[0066] Figure 6A cross-sectional side view of a blade 100 including an LTS assembled to a turbine base B according to another preferred embodiment is shown. It will be appreciated that the transmission system and the nacelle external to the blade are omitted. The blade 100 may be any blade disclosed herein in accordance with the invention. As previously described, the blade 100 comprises a wall 10 which may comprise any number of layers, such as two layers 15a, 15b forming the inner and outer surfaces of the blade 100, respectively, and an inner layer 7, the layers 15a, 15b forming the inner and outer surfaces of the blade 100, respectively, and in some embodiments the inner layer 7 may comprise conductive elements and / or water absorbing material as previously disclosed. The blade comprises a base portion 6 which may be partially embedded between the layers 15a and 15b and in contact with the inner layer 7. The LTS system of the blade 100 comprises a first conductor element 4 which is connected in the inner side of the blade to a down conductor 1 by an electrical connection 9a which may comprise a conductor plate 3 which is mounted to the blade 100 by one or more electrically insulating mounting elements 2. The electrical connection 9a may be in accordance with reference Figure 5 According to a preferred embodiment, the first conductor element 4 is electrically connected to a second conductor element 5 on the outside of the blade, the second conductor element 5 forming a conductive surface from which the current can be transferred to an external grounding element (not shown). The second conductive element 5 can be regarded as equivalent to Figure 1 Lightning transmitter 30.

[0067] Although Figure 6 In the embodiment, the first conductor element 4 is shown as a cable having a bending radius, but it should be noted that in other embodiments the first conductor may be a straight cable or other conducting element such as a flat steel bar or plate.

[0068] It should be noted that Figure 6 The blade 100 is shown as comprising two layers 15a, 15b and an inner layer 7. It will be appreciated that the blade may comprise more or fewer than three layers, or be a single, unitary body. Furthermore, the first conductor element 4 may be provided at any suitable angle relative to the surface of the wall 10. The first conductor element 4 may be connected to the down conductor 1 and the second conductor element 5 at a distance from the inner and outer surfaces of the wall 10 of the blade 100, respectively. In other embodiments, the electrical connections 9a and / or 9b may be provided at or on the inner and / or outer surfaces of the wall 10 of the blade 100.

[0069] According to one or more embodiments, the second conductor element 5, which forms a conductive surface from which lightning current can be transmitted between the first conductor element 4 and the external grounding element, can be mounted to the blade by an electrically insulating mounting element (not shown), such as the previously disclosed electrically insulating mounting element 2. The electrically insulating element can include any insulating material, such as plastic, rubber, or nylon. The second conductor element 5 can be mounted to the blade 100 by an adhesive, such as a silicone adhesive or any other suitable adhesive. It should be noted that the electrically insulating mounting element of the second conductor element 5 can be composed entirely of a single insulating material, or can include any other insulating or non-insulating material, as long as the electrically insulating element still provides complete electrical insulation between the second conductor element 5 and the surface of the blade.

[0070] According to the reference Figure 6 In the more preferred embodiment shown, the second conductor element 5 comprises a conductive portion extending around the blade 100 in a direction perpendicular to the longitudinal axis 120 of the blade 100. It will be appreciated that Figure 6 Elements of the lightning transmission system external to the blade 100, as well as the nacelle, are omitted. The blade 100 can be rotated about the longitudinal axis 120 to change the blade 100's angle of attack α, thereby optimizing turbine operation under different conditions, such as varying wind speeds and directions. As the blade 100's angle of attack α changes, the size of the air gap between the second conductor element 5 and the grounding element on the turbine's nacelle may change if the second conductor element 5 does not extend perpendicular to the longitudinal axis 120. Advantageously, providing the conductive portion of the conductor element 5 extending perpendicular to the longitudinal axis 120 reduces the maximum air gap with the grounding element as the angle of attack α changes, which means that the preferred electrical path is maintained. In other words, as the angle of attack α changes, the relative position of the second conductor element 5 with the grounding element can change. Therefore, extending the second conductor element 5 perpendicular to the longitudinal axis 120 of the blade 100 (i.e., in the rotational direction of the angle of attack α) helps the LTS system maintain the conductive portion of the second conductor element 5 close to the grounding element.

[0071] Even more preferably, the angular extent of the second conductor element 5 in a plane perpendicular to the longitudinal axis 120 is equal to or greater than the range of angles of attack α at which the blade 100 is configured to operate. In a preferred embodiment, the angular extent of the second conductor element 5 on the surface of the blade 100 is 90°. Advantageously, this further configures the conductive surface formed by the second conductor element 5 to be close to the ground element at any angle of attack α to which the blade can be set.

[0072] It should be noted that the vertical direction in which the second conductor element 5 extends around the blade 100 is not exclusive, and the second conductor element 5 may also extend in another direction that is not perpendicular to the longitudinal axis 120 of the blade 100. For example, Figure 6In FIG, the second conductor element 5 extends along the blade surface in a direction parallel to the longitudinal axis α of the blade. Furthermore, it should be noted that the second conductor element 5 may take several shapes around the blade and may not be conformal to the blade surface, or it may be provided at a distance from the blade surface.

[0073] According to Figure 6 In an even more preferred embodiment shown in , the second conductor element 5 is mounted to and conforms to the outer surface of the blade 100. It should be noted that in some embodiments, only a portion of the second conductor element 5 may conform to the surface, while some other portion may not conform to the surface of the blade 100.

[0074] According to a second aspect of the present invention, there is provided a wind turbine comprising one or more wind turbine blades according to any blade of the first aspect of the present invention.

[0075] It should be noted that a wind turbine may include two or more blades according to the first aspect of the present invention. For example, all blades may be blades according to the first aspect of the present invention, or some blades may be blades according to the first aspect of the present invention, while other blades may not include an LTS according to the present invention. It should also be noted that when a turbine includes more than one blade according to the first aspect of the present invention, each of the blades according to the first aspect of the present invention may be described according to a different embodiment of the first aspect of the present invention.

[0076] Figure 7 A cross-sectional view of a blade 100 including an LTS as part of a turbine according to one or more embodiments is shown. Figure 7 Some elements of the turbine are omitted, such as the nacelle to which the grounding element 60 is mounted. The blade 100 may be a blade according to the present invention disclosed herein, and in particular with reference to Figure 3 、 Figure 4A 、 Figure 4B 、 Figure 5 and Figure 6 The wind turbine comprises a nacelle (not shown), and the nacelle comprises a grounding element 60 for receiving lightning from the LTS of one or more wind turbine blades. The grounding element 60 is configured to act as a receiver of current from and to the second conductor element 5 of the LTS in the outer surface of the blade 100.

[0077] The ground element 60 may be any suitable ground element as is known in the art and may be connected to earth in a number of different ways. Figure 8A schematic diagram of a wind turbine according to one or more embodiments is shown. The wind turbine comprises a blade 100 connected to a nacelle 200, which may be any blade according to the invention disclosed herein (other blades have been omitted for simplicity). The nacelle 200 comprises a generator 210 and a set of electronic devices 220 electrically connected to the base of the blade 100. The blade 100 according to one or more embodiments of the first aspect of the invention comprises an LTS comprising a lightning receptor configured to receive lightning striking the blade, a down conductor 1 and a lightning transmitter 30 for transmitting the lightning current away from the blade 100. The wind turbine nacelle 20 comprises a grounding element 60 configured as a receiving device for lightning from the grounding element 60. The grounding element is grounded by an electrical pathway 65 in the form of a cable, which is electrically insulated from the internal components of the nacelle 200, i.e. from both the generator 210 and the set of electronic devices 220. In Figure 8 As can be seen in FIG6 , the electrical pathway 65 is designed to flow through the nacelle 200 and tower 300 of the wind turbine. However, in other embodiments, the electrical pathway 65 may be designed on the outside of the nacelle 200 and / or tower 300 and may include other elements than cables (such as plates), or it may be included within the surface of the nacelle, or the nacelle 200 and tower 300 themselves may include or consist of conductive material such that they form the electrical pathway 65. Furthermore, the electrical pathway may include more than one element and may not interact with the nacelle 200 and / or tower 300 (e.g., via a cable directly grounded to earth).

[0078] In the reference Figure 7 In the further preferred embodiment shown, the grounding element 60 of the nacelle comprises a third conductor element 62 extending in a direction around the axis of rotation of the wind turbine. Figure 7 , it can be seen that the third conductor element 62 extends in a direction about the wind turbine's axis of rotation, thereby defining a circumferential arc about this axis of rotation. Advantageously, this allows the grounding element 60 to receive lightning current from the LTS of one or more wind turbine blades as the blade 100 rotates about the wind turbine's axis of rotation.

[0079] It should be noted that Figure 7The embodiment illustrated in FIG includes a conductive bridge 50 located between the second conductor element 5 and the grounding element 60 for reducing the air gap between the second conductor element 5 and the grounding element 60. It should be understood that in other embodiments, the lightning transmission system of the turbine does not include the conductive bridge 50, but rather includes other elements for transmitting current from the blades (i.e., the conductive elements 5) to the ground. The turbine can include any transmission system known in the art for transmitting current from the base of the blades to the ground. The transmission system can include any contact system known in the art (including brushes connected to the ground and configured to contact the blades), or any other non-contact system, or a hybrid contact / non-contact system.

[0080] The third conductor element 62 can extend over a specific angle in a direction around the wind turbine's axis of rotation. In some embodiments, it can extend 360°, thereby defining a full circle, or it can extend only 180°, thereby defining a half-circle, such as the upper half of the turbine. Because lightning typically strikes the blades at their highest point, the 180° arc of the third conductor element 62 on the upper half of the nacelle still provides a functional grounding element 60.

[0081] In such Figure 7 In another preferred embodiment shown in FIG, the grounding element 60 is

[0082] Figure 9 A cross-sectional view of a wind turbine with a blade 100 comprising an LTS is shown. The blade 100 may be any blade according to the invention disclosed herein. According to another further preferred embodiment, the wind turbine further comprises one or more conductive bridges 50 located between the one or more blades and a nacelle (not shown), the one or more conductive bridges 50 being configured to reduce the air gap between the LTS of the one or more blades 100 and a grounding element 60 mounted to the nacelle. Advantageously, this reduces the air gap between the blade and the nacelle and, therefore, reduces the breakdown voltage of this path. The conductive bridges 50 are attached by insulating supports 55. It should be noted that the one or more conductive bridges 50 may be mounted to a rotating part of the turbine (i.e. fixed relative to the blade 100).

[0083] It should also be noted that other mechanisms for transferring lightning from the blade to the turbine may be provided. For example, in some embodiments, brush contacts may be provided between the grounding element 60 and the outer conductor element 5 so that an electrical connection is maintained between the blade and the nacelle during rotation.

[0084] It should be noted that Figure 9 A blade 100 is disclosed comprising a wall having a unitary body. However, it should be understood that the wall may comprise any of the elements disclosed with reference to the other figures, such as layers 15a, 15b and 7. It should be noted that Figure 9The conductor bridge 50 in FIG. 5 is in a “T” shape and is attached to the base of the blade, however, it should be noted that any other shape may be envisaged for the conductor bridge 50 .

[0085] Figure 10 A cross-sectional view of a wind turbine having a blade 100 including an LTS is shown. The blade 100 may be any blade according to the present invention disclosed herein. However, alternative references Figure 9 In the disclosed conductive bridge 50, the second conductive element 5 comprises a curved frame including a curved surface 5a. The curved surface 5a may be flexible or adjustable. The curved surface is configured to closely approach or even contact the third conductor element 62 on the nacelle, resulting in virtually no air gap between the nacelle and the blade's lightning transmission system, and thus virtually no breakdown voltage associated with the desired path to ground. The curved surface 5a may have a curved shape configured to contact the third conductor element regardless of the blade 100's angle of attack.

[0086] A third aspect of the invention relates to a method of attaching a lightning transmission system to a wind turbine blade. Figure 11 A method 900 of attaching a lightning transmission system to a wind turbine blade according to one or more embodiments is shown. The method 900 includes the following steps.

[0087] First, method step 902 includes providing a wind turbine blade. The wind turbine blade can be any type of wind turbine blade as known in the art, regardless of its construction material, size, or functional design. Thus, it can be used in onshore wind turbines or offshore wind turbines. The wind turbine blade can be manufactured in step 902 or can be part of an existing wind turbine that includes at least one wind turbine blade having surfaces defining an interior and an exterior of the blade.

[0088] Next, method step 904 includes providing an insulated lightning transmission system (LTS) for a wind turbine blade, the LTS including a first conductor element including an electrical insulation layer, the step including extending the first conductor element through the wind turbine blade. The LTS may also include several elements, such as a lightning receptor, a lightning transmitter, and a down conductor configured to connect the lightning receptor and the lightning transmitter. The first conductor element is configured to provide a connection between the down conductor and the lightning transmitter. It should be noted that several alternative options for these elements may be provided, as known in the art. The first conductor element may be any conductive element, such as a cable or a bolt including an electrical insulation layer. The LTS system may be any LTS system described herein according to the present invention.

[0089] Finally, method step 906 includes mounting the LTS to the wind turbine blade, including extending the first conductor element through the blade wall between the interior and exterior of the blade wall. If the blade is already part of a wind turbine, this step can be performed for a plurality of blades or all blades of the turbine. This step can be performed, for example, by drilling a hole through the surface of the blade, which hole allows the first conductor element to extend through the blade surface between the interior and exterior of the blade surface. Alternatively, a hole already provided in the blade or from a previous first conductor element can be used. The different elements of the LTS (such as the lightning receptor, lightning transmitter, and down conductor) can be connected as is known in the art.

[0090] It should be noted that the method can be applied to wind turbine blades already in use by attaching or replacing a lightning transmission system to one or more wind turbine blades as outlined above. Alternatively, the method can be applied to wind turbine blades during their manufacturing process (i.e., before the wind turbine is assembled).

[0091] A fourth aspect of the present invention relates to a method of generating electrical power using a wind turbine according to any of the second aspects of the present invention. Advantageously, the wind turbine preferably more efficiently transmits lightning through the blades and to grounded elements, without reaching sensitive components of the wind turbine, such as bearings or electronics. This reduces the probability of lightning deviating from the preferred path of the LTS design, which could damage or deteriorate any sensitive components of the wind turbine.

[0092] All of the above are fully within the scope of the present disclosure and are to be considered as forming the basis of alternative embodiments in which one or more combinations of the above features are employed without limitation to the specific combinations disclosed above.

[0093] In view of this, there will be many alternatives for implementing the teachings of this disclosure. It is expected that those skilled in the art will be able to modify and adapt the above disclosure to suit their own circumstances and needs within the scope of this disclosure, while retaining some or all of its technical effects (whether disclosed or derived from the above) according to their common knowledge in the art. All such equivalents, modifications or adjustments fall within the scope of this disclosure.

Claims

1. A wind turbine blade comprising a lightning transmission system for transmitting lightning current through the wind turbine blade, the lightning transmission system comprising one or more lightning receptors, a down conductor electrically connected to each of the one or more lightning receptors and extending along an interior of the wind turbine blade, and a first conductor element proximate a base portion of the wind turbine blade, the first conductor element electrically connected to the down conductor and extending through the blade wall between an interior surface and an exterior surface of the wall of the blade, wherein The first conductor element includes an electrical insulation element that configures the first conductor element to be electrically insulated from the blade; wherein a dielectric strength of the electrical insulation element is greater than a dielectric strength of the blade at a location through which the first conductor element extends.

2. The wind turbine blade according to claim 1, wherein: The electrical insulation element is provided at least along a portion of the first conductor element that traverses the surface of the blade.

3. The wind turbine blade according to claim 1 or 2, wherein: The first conductor element is electrically connected to one or more other conducting elements via one or more electrical connections provided at a distance away from the inner and / or outer surface of the blade such that an air gap is provided between the one or more electrical connections and the surface of the blade.

4. The wind turbine blade according to claim 3, wherein: At least one of the electrical connections comprises a conductive plate mounted to an interior surface of the blade via one or more electrically insulating mounting elements; and / or wherein, At least one of the electrical connections comprises a conductive plate mounted to an exterior surface of the blade via one or more electrically insulating mounting elements.

5. A wind turbine blade according to any one of the preceding claims, wherein The blade comprises an electrically conductive material and / or a water absorbing material, and the first conductor element traverses the electrically conductive material and / or the water absorbing material.

6. A wind turbine blade according to any one of the preceding claims, wherein The first conductor element is electrically connected to a second conductor element on an outer side of the blade, the second conductor element forming a conductive surface from which the current is configured to be transferred between the blade and an external ground element.

7. The wind turbine blade according to claim 6, wherein: The second conductor element extends around the blade in a direction perpendicular to the longitudinal axis of the blade, preferably wherein, The angular extent of the second conductor element in a plane perpendicular to the longitudinal axis is equal to or greater than the range of angles of attack at which the blade is configured to operate.

8. The wind turbine blade according to claim 7, wherein: The second conductor element is mounted to the outer surface of the blade and conforms to the surface.

9. A wind turbine comprising one or more wind turbine blades according to any one of claims 1 to 8.

10. The wind turbine according to claim 9, wherein: The wind turbine comprises a nacelle, wherein the nacelle comprises a grounding element for receiving lightning from the lightning transmission system of the one or more wind turbine blades.

11. The wind turbine according to claim 10, wherein: The grounding element of the nacelle comprises a third conductor element extending in a direction around the rotation axis of the wind turbine.

12. A wind turbine according to any one of claims 10 or 11, wherein: The wind turbine further includes one or more conductive bridges between the one or more blades and the nacelle, the one or more conductive bridges being configured to reduce an air gap between the lightning transmission system of the one or more blades and the grounded element of the nacelle.

13. A wind turbine according to any one of claims 10 to 12, wherein: For the one or more blades, a breakdown voltage of a path of current from the lightning transmission system to the grounding element is lower than a breakdown voltage of any path of current from the first conducting element to the base portion of the blade.

14. A method of attaching a lightning transmission system to a wind turbine blade, comprising: d) providing wind turbine blades; e) providing a lightning transmission system for said wind turbine blade, said lightning transmission system comprising a first conductor element, said first conductor element comprising an electrically insulating element; f) Mounting the lightning transmission system to the wind turbine blade, comprising extending the first conductor element through the blade wall between an inner surface and an outer surface of the wall of the blade.

15. A method of generating electrical power using a wind turbine according to any one of claims 9 to 13.

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