CN118451250A - Lightning protection system - Google Patents

Abstract

A wind turbine blade having a blade shell with a lightning protection system; the lightning protection system comprises: a first conductive pin and a second conductive pin adjacent to the first conductive pin; a metal layer at an outer surface of the blade shell, the metal layer being divided into a first portion and a second portion with a discontinuity between the first portion and the second portion; wherein the first conductive pin extends through a first portion of the metal layer and not through a second portion of the metal layer; and wherein the second conductive pin extends through the second portion of the metal layer and not through the first portion of the metal layer.

Description

Lightning protection system

Technical Field

The present invention relates to a wind turbine blade having a blade shell with a lightning protection system and a method of manufacturing a wind turbine blade having a blade shell.

Background

Wind turbines are prone to lightning strikes and wind turbine blades are particularly prone to lightning strikes.

Accordingly, wind turbine blades often include lightning protection systems that electrically couple the wind turbine blade to ground. The lightning protection system may include a lightning receptor and a conductor electrically connected from the blade to ground through the tower and the nacelle. The lightning protection system may further comprise a Surface Protection Layer (SPL), such as a metal mesh or foil surface protection layer, incorporated into the blade shell at the outer surface of the blade and extending along at least a portion of the blade. The surface protection layer typically covers a substantial portion of the blade surface and intercepts lightning strikes before they reach the electrically conductive gas elements of the blade. The surface protection layer is typically connected to the lightning protection system at a number of points in order to ensure a good electrical connection from the surface protection layer.

Disclosure of Invention

A first aspect of the invention provides a wind turbine blade having a blade shell with a lightning protection system; the lightning protection system comprises: a first conductive pin and a second conductive pin adjacent to the first conductive pin; a metal layer at an outer surface of the blade shell, the metal being divided into a first portion and a second portion, with a discontinuity between the first portion and the second portion; wherein the first conductive pin extends through a first portion of the metal layer and not through a second portion of the metal layer; and wherein the second conductive pin extends through the second portion of the metal layer and not through the first portion of the metal layer.

A second aspect of the invention provides a method of manufacturing a wind turbine blade having a blade shell, the method comprising: providing a blade mould and providing a metal layer of a lightning protection system of the blade shell, wherein the metal layer is divided into a first part and a second part; determining respective blade positions of the first conductive pin and the second conductive pin; laying a first portion of the metal layer in the blade mold so as to cover the determined blade position of the first conductive pin but not the determined blade position of the second conductive pin; a second portion of the metal layer is laid in the blade mold so as to cover the determined blade position of the second conductive pin but not the determined blade position of the first conductive pin.

With this arrangement, the degree of warpage and/or shearing of the metal layer can be reduced because the operability of the plurality of smaller discrete metal layer portions is greater than a single unitary metal layer portion comprising a plurality of conductive pin locations, each having a determined blade location. This advantage is further emphasized when considering the ability of the metal layer to conform to the three-dimensional shape of the blade, as the hooking of the metal layer can be significantly complicated when there are two determined blade positions for the corresponding conductive pins within a single portion of the metal layer. Having multiple portions of the metal layer may also reduce the effects of any machining or manufacturing errors and accommodate variations in the metal layer in the multiple blade shapes within the blade family, as only a portion of the metal layer may be affected.

The first portion and the second portion may partially overlap to form an overlap region.

The wind turbine blade may comprise an electrical component, wherein a first portion of the metal layer is electrically connected to the electrical component by a first conductive pin and a second portion of the metal layer is electrically connected to the electrical component by a second conductive pin.

The electrical component may be a down conductor of a lightning protection system.

The first conductive pin may extend through a first unitary disc formed across the metal layer and/or the second conductive pin may extend through a second unitary disc formed across the metal layer.

The metal layer may be a first metal layer and the lightning protection system may further comprise a second metal layer at the outer surface of the blade shell. The second metal layer may be divided into a first portion and a second portion with a discontinuity therebetween, wherein the first portion of the second metal layer is stacked on the first portion of the first metal layer to form intimate electrical contact with the first portion of the first metal layer, and wherein the first conductive pin extends through the first portion of the first metal layer and the first portion of the second metal layer; and/or wherein a second portion of the second metal layer is stacked on the second portion of the first metal layer to form a tight electrical contact with the second portion of the first metal layer, and wherein the second conductive pin extends through the second portion of the first metal layer and the second portion of the second metal layer.

The first monolithic disc may extend through the first portion of the first metal layer and the first portion of the second metal layer, and/or the second monolithic disc may extend through the second portion of the first metal layer and the second portion of the second metal layer.

The first and second portions of the first metal layer and/or the first and second portions of the second metal layer may be formed of the same material. The first and second portions of the first metal layer and/or the first and second portions of the second metal layer may have the same thickness.

The first metal layer and the second metal layer may be formed of different materials. The first portion of the first metal layer may be formed of a different material than the second portion of the first metal layer. The first portion of the second metal layer may be formed of a different material than the second portion of the second metal layer. The different materials may be aluminum and copper.

The step of laying a first portion of the metal layer in the blade mould may further comprise: aligning the pin locating feature of the first portion of the metal layer with the determined blade position of the first conductive pin; and/or the step of laying the second portion of the metal layer in the blade mould may further comprise: the pin locating feature of the second portion of the metal layer is aligned with the determined blade position of the second conductive pin.

The step of laying a second portion of the metal layer in the blade mould may further comprise: the edge of the second portion is overlapped with the edge of the first portion to form an overlap region.

The method of manufacturing a wind turbine blade may further comprise: extending a first conductive pin through a first portion of the metal layer and coupling the first conductive pin to the down conductor; and/or extending a second conductive pin through a second portion of the metal layer and coupling the second conductive pin to the down conductor.

The method of manufacturing a wind turbine blade may further comprise: laying a fibrous layer of the blade shell in a blade mould; and consolidating the fiber layer and the metal layer in the blade mold, and integrating the fiber layer and the metal layer with resin.

The method of manufacturing a wind turbine blade may further comprise, prior to laying the metal layer in the blade mould: providing one or more first metal disc components; and heating the one or more first metal disk components to form a first unitary metal disk extending through the first portion of the metal layer; and/or providing one or more second metal disc components; and heating the one or more second metal disk components to form a second unitary metal disk extending through the second portion of the metal layer.

Drawings

Embodiments of the present invention will now be described with reference to the accompanying drawings, in which:

FIG. 1 illustrates a wind turbine;

FIG. 2 illustrates a wind turbine blade;

FIG. 3 shows a plan view of a lightning protection system for a wind turbine blade, the lightning protection system comprising metal layers in the blade shell of the blade;

FIG. 4 illustrates a chordwise cross section of a blade shell of a wind turbine blade;

Fig. 5 shows the overlap region between portions of the metal layer;

FIG. 6 shows a metal layer connected to a lightning protection system by an electrical component;

FIG. 7 illustrates a conductive pin extending through the outer layer of the blade;

FIG. 8A shows a pair of metal disc portions on both sides of a surface protective layer;

FIG. 8B illustrates a metal disk extending through a surface protective layer;

FIG. 8C shows holes formed through the surface protective layer;

FIG. 8D shows a conductive pin extending through a hole;

FIG. 8E shows a conductive pin connected to the lightning protection system;

FIG. 9 illustrates a plan view of a portion of a lightning protection system including a plurality of discrete metal layer portions;

FIG. 10 shows a plan view of an alternative arrangement of multiple discrete metal layer portions;

FIG. 11 illustrates a discontinuity between a first portion and a second portion of a metal layer that form an overlap region between a location of a first conductive pin and a location of a second conductive pin;

FIG. 12A illustrates a blade mold;

FIG. 12B illustrates a first portion of a metal layer laid in a blade mold;

FIG. 12C illustrates a second portion of the metal layer laid in the blade mold;

FIG. 12D illustrates a third portion of a metal layer laid in a blade mold;

FIG. 12E shows a fiber layer laid on a blade mold;

FIG. 12F illustrates a blade mold covered by a vacuum bag;

FIG. 12G illustrates a portion of a blade removed from a blade mold;

FIG. 13 shows a conductive pin extending through a surface protection layer comprising two metal layers;

fig. 14 shows a schematic view of a lightning protection system comprising two metal layers, each comprising a plurality of discrete portions.

Detailed Description

In this specification terms such as leading edge, trailing edge, pressure surface, suction surface, thickness, chord and plan view are used. Although these terms are well known and understood by those skilled in the art, for the avoidance of doubt, the following definitions are given.

The term "leading edge" is used to refer to the edge of a blade that will be located in front of the blade when the blade is rotated in the normal direction of rotation of the wind turbine rotor.

The term "trailing edge" is used to refer to the edge of a wind turbine blade that will be located at the rear of the blade when the blade is rotated in the normal direction of rotation of the wind turbine rotor.

The "chord" of a blade is the linear distance from the leading edge to the trailing edge in a given cross-section perpendicular to the spanwise direction of the blade. The term "chordwise" is used to refer to a direction from the leading edge to the trailing edge and vice versa.

The "pressure surface (or windward surface)" of a wind turbine blade is the surface between the leading edge and the trailing edge that has a higher pressure than the suction surface of the blade when the blade is in use.

The "suction surface (or lee surface)" of a wind turbine blade is the surface between the leading edge and the trailing edge which will have a lower pressure than the pressure surface acting on it when the blade is in use.

The "thickness" of a wind turbine blade is measured perpendicular to the chord of the blade and is the maximum distance between the pressure surface and the suction surface in a given cross-section perpendicular to the spanwise direction of the blade.

The term "spanwise" is used to refer to a direction from the root end of a wind turbine blade to the tip end of the blade and vice versa. When the wind turbine blade is mounted on a wind turbine hub, the spanwise and radial directions will be substantially the same.

Views perpendicular to the spanwise and chordwise directions are referred to as "plan views". This view is seen along the thickness dimension of the blade.

The term "spar cap" is used to refer to a longitudinal, generally spanwise extending stiffening member of the blade. The spar caps may be embedded in the blade shells or may be attached to the blade shells. Spar caps on the windward and leeward sides of the blade may be connected by one or more shear webs extending through the interior hollow space of the blade. The blade may have more than one spar cap on each of the windward and leeward sides of the blade. The spar caps may form part of a longitudinally reinforced spar or support member of the blade. In particular, the first spar cap and the second spar cap may form part of a load carrying structure extending in the longitudinal direction, which carries the flap-wise bending load of the blade.

The term "shear web" is used to refer to a longitudinal, generally spanwise extending stiffening member of a blade that is capable of transferring loads from one of the windward and leeward sides of the blade to the other of the windward and leeward sides of the blade.

FIG. 1 illustrates a wind turbine 10 that includes a tower 12 mounted on a foundation and a nacelle 14 positioned at an apex of the tower 12. The wind turbine 10 shown here is an onshore wind turbine such that the foundation is embedded in the ground, but the wind turbine 10 may be an offshore facility, in which case the foundation will be provided by a suitable offshore platform.

The rotor 16 is operatively connected to a generator (possibly through a gearbox) (not shown) housed within the nacelle 14. Rotor 16 includes a central hub 18 and a plurality of rotor blades 20 that project outwardly from central hub 18. It should be noted that wind turbine 10 is a Horizontal Axis Wind Turbine (HAWT) of a conventional type such that rotor 16 is mounted at nacelle 12 for rotation about a substantially horizontal axis defined at the center of hub 18. Although the example shown in FIG. 1 has three blades, one skilled in the art will recognize that other numbers of blades are possible.

As wind blows toward wind turbine 10, blades 20 generate lift, which rotates rotor 16, which, in turn, causes an electrical generator within nacelle 14 to generate electrical energy.

Fig. 2 shows an example of a wind turbine blade 20 for use in such a wind turbine. The blade 20 has a root end 21 proximal to the hub 18 and a tip end 22 distal to the hub 18. Blade 20 includes a leading edge 23 and a trailing edge 24 extending between root end 21 and tip end 22. Blade 20 includes a suction surface 25 and a pressure surface 26. The thickness dimension of the blade extends between the suction surface 25 and the pressure surface 26.

Blade 20 has a generally circular cross-section near root end 21. The blade portion near the root must have sufficient structural strength to support the blade portion outside the segment and transfer the load into the hub 18. Moving from the root end 21 of the blade towards the "shoulder" 28 of the blade, the blade 20 may transition from a circular profile to an airfoil, the shoulder 28 being the widest portion of the blade 20 where the blade 20 has its maximum chord. The blade 20 has an airfoil of progressively reduced thickness at the outboard portion of the blade extending from the shoulder 28 to the tip end 22.

The wind turbine blade 20 may include an outer blade shell defining a hollow interior space having a shear web extending internally between an upper portion and a lower portion of the blade shell.

As schematically shown in fig. 3, the blade 20 may include one or more lightning receptors 36 and one or more lightning down conductor cables 38, which form part of the lightning protection system of the wind turbine. The lightning receptor attracts the lightning strike and a down conductor cable 38 passing through the hollow interior of the blade conducts the energy of the lightning strike down to ground potential via the nacelle 14 and the tower 12. Further, the lightning protection system may include a surface protection layer 40 at the outer surface of the blade. The surface protection layer 40 may be electrically connected to the down-lead cable 38 at each end.

A majority of the outer surface of the blade 20 may be covered with the surface protection layer 40, or only a portion of the outer surface of the blade 20 may be covered with the surface protection layer 40. The surface protection layer 40 serves to protect the conductive material in the blade from lightning strikes and may be used as a lightning receptor, down conductor or both. The down conductor may extend substantially the entire length of the blade. In some examples, for example, where a majority of the outer surface of the blade 20 is covered with the surface protection layer 40, the down conductor cable 38 may be connected to the surface protection layer 40 adjacent the tip end 22 of the blade and adjacent the root end 21 of the blade, while a majority of the surface protection layer 40 covered with the surface protection layer 38 is absent along the length of the blade. The surface protective layer 40 may extend from the root to the tip, in which case the down-lead cable 38 may not be required. The surface protection layer 40 may extend in segments along the length of the blade with down conductor cable segments between the segments of the surface protection layer 40. Alternatively, the down-lead cable 38 may extend below the surface protection layer 40 (within the blade) such that the down-lead cable 38 and the surface protection layer 40 are electrically connected in parallel.

At the root end 21 of the blade 20, the down-conductor cable 38 may be electrically connected to a charge transmission line via an armature device, to ground potential via the nacelle 14 or hub 18 and the tower 12. Thus, such a lightning protection system allows for safe guiding of lightning from the blade to ground potential, thereby minimizing the risk of damaging the wind turbine 10.

The down-lead cable 38 and the surface protective layer 40 may be connected by one or more connectors or receivers. The connector may include conductive pins 61 extending through the surface protective layer 40 and connected to the down-conductor cable 38. Fig. 3 shows five conductive pins 61 connecting the down-lead cable 38 and the surface protective layer 40, but it should be understood that any suitable number of conductive pins 61 may be used.

The surface protection layer 40 may extend to the leading edge 23 of the wind turbine blade 20 and/or to the trailing edge 24 of the wind turbine blade 20. Alternatively, the surface protection layer 40 may be spaced apart from the leading and/or trailing edges of the blade 20.

Fig. 4 shows a chordwise cross section of the blade shell adjacent the suction surface of the wind turbine blade 20 as seen in the spanwise direction of the blade 20, although it will be clear that the characteristics of the blade shell adjacent the pressure surface of the wind turbine blade 20 may be substantially identical.

Blade 20 includes spar caps 50, and shear webs (not shown) are attached to the blade shells at spar caps 50. Spar caps 50 are incorporated into the blade shells. In an alternative arrangement, the spar caps 50 may be connected to the interior of the blade shell. Spar cap 50 is an elongated reinforcing structure that extends from root end 21 to tip end 22 along substantially the entire length of blade 20.

A core 54, such as a foam, balsa wood, or honeycomb core, may be located on either side of spar cap 50. One or more fiber layers 53 may be provided inboard of the spar caps 50, such as glass fiber layers or carbon fiber layers, the fiber layers 53 forming the inner surface 51 of the blade 20. The fibrous layers may be impregnated with resin to form a composite material, or may be prepreg composite layers. Similarly, one or more layers 56 may be disposed outboard of spar caps 50. With the spar caps connected to the interior of the blade shell, the core 54 may be filled between one or more fiber layers 51 and one or more fiber layers 53.

Spar cap 50 may comprise an electrically conductive material, such as carbon fiber. For example, the spar caps 50 may include a pultruded fiber strip material, such as a pultruded carbon fiber composite or other carbon fiber reinforced plastic material.

Spar cap 50 may be equipotential bonded to surface finish 40 to ensure that no charge builds up in the spar cap or that there is no large voltage differential between surface finish 40 and spar cap 50 in the event of a lightning strike. The equipotential bonding also prevents arcing between the surface protective layer 40 and the spar caps 50, which could damage the blade. As shown in fig. 4, the surface protective layer 40 may have a chord-wise extent in the chord-wise direction of the blade 20 that is wider than the width of the spar caps 50. This helps ensure that the spar caps 50 are well protected from lightning strikes by the surface protection layer 40.

As previously described, the surface protection layer 40 is a conductive layer located at the outer surface 52 of the blade 20, however, as can be seen in fig. 4, the blade 20 may include one or more of the following: a fleece layer 58; and a gel layer and/or a lacquer layer 59. For example, the fleece layer 58 and gel layer 59 may be located between the surface protection layer 40 and the outer surface 52 of the blade 20.

The surface protection layer 40 includes a metal layer 41. The metal layer 41 is divided into at least a plurality of portions 41a,41b with a discontinuity between each portion 41a,41 b. Fig. 5 shows an example of a discontinuity between the first portion 41a and the second portion 41 b. In general, first portion 41a and second portion 41b of metal layer 41 partially overlap to form overlap region 43. The discontinuity between the portions 41a,41b of the metal layer 41 may enable the metal layer portions 41a,41b to be laid down sequentially in the blade mould and/or to be moved relative to each other within the mould before they are incorporated into the blade shell.

The overlap regions 43 (alternatively referred to as overlapping edges) may help provide the desired electrical connection across the metal layer 41, however the size of these overlap regions 43 is typically minimized. For example, the overlap region 43 may have an overlap width of less than 200mm, and typically less than 100mm.

Each portion 41a,41b of the metal layer 41 may be connected to the lightning protection system by a respective electrical element. Fig. 6 shows an example in which the conductive pin 61 extends through the first metal layer portion 41a to the receiving block 83. As will be apparent from the examples shown below, the second metal layer portion 41b separated from the first metal layer portion 41a by a discontinuity may be similarly arranged. Specifically, the conductive pins 61 of the first metal layer portion 41a may extend through the first metal layer portion 41a without through the second metal layer portion 41b, and the conductive pins of the second metal layer portion 41b may extend through the second metal layer portion 41b without through the first metal layer portion 41a (as described in further detail with respect to fig. 11). The receiving block 83 connected to the conductive pin 61 is conductive and may be connected to a down-conductor cable 38 extending through the blade 20. In this way, the metal layer 41 may form part of the lightning protection system of the wind turbine blade 20.

As shown in fig. 7, the conductive pin 61 may extend through a plurality of other components, such as the metal disc 80, one or more fibrous layers 56, and further structural components 48 (e.g., including additional fibrous layers, a core material such as foam, etc., as will be appreciated by those skilled in the art) in extending through the first portion 41a of the metal layer to the receiving block 83. The receiving block 83 may be bonded to an inner surface of the blade 20, for example, the receiving block 83 may be bonded to the structural member 48.

To facilitate good electrical contact between the first portion 41a (or any other portion) of the metal layer 41 and its corresponding connector (particularly the conductive pin 61), the metal layer 41 may include a reinforcing region. Fig. 8A-8E illustrate examples of forming the reinforcing region wherein the connector includes a disk 80 extending through metal layer 41, but it should be understood that the reinforcing region may include any suitable conductive element.

The metal disc 80 may be formed from one or more metal disc components. The metal disc component may be a pair of metal disc portions 81a,81b, as shown in FIG. 8A, for example. The metal disc portions 81a,81b may be placed on both sides of the first portion 41a of the metal layer 41 such that the metal layer 41 is sandwiched between the first metal disc portion 81a and the second metal disc portion 81 b.

The metal disk portions 81a,81b may then be consolidated to form a single (unitary) metal disk 80 extending through the first portion of metal layer 41. Fig. 8B shows an example of a metal disk 80 extending across metal layer 41.

In some examples, metal disc 80 may be formed by heating first metal disc portion 81a and second metal disc portion 81b together. Alternatively, metal disc 80 (shown in FIG. 8B) may be cast from molten metal to form metal disc 80 extending through metal layer 41.

As shown in fig. 8C, one or more fiber layers 56 may be disposed on a metal disk 80. A drill 85 or other device may form a hole 86 through the metal disc 80 and the fiber layer 56 to provide a through hole for inserting the conductive pin 61 (shown in fig. 8D). By forming the through hole, the disk 80 becomes annular.

The conductive pin 61 may extend through the aperture 86 to electrically connect the metal layer 41a to the rest of the lightning protection system. For example, fig. 8E shows a conductive pin 61 extending through the metal disc 80 to the receiving block 83 and, in so doing, through the first portion 41a of the metal layer 41 and the plurality of fiber layers 56. As previously mentioned, the conductive pin 61 may also extend through other structural components.

As shown in fig. 3, the lightning protection system may include a plurality of conductive pins 61 adjacent to each other. Adjacent in this context may mean that the first and second conductive pins 61 are within 5%,4%,3%,2% or 1% of each other of the total blade length.

When first metal layer 41 includes more than one discrete reinforcing region, for example, when metal layer 41 is designed such that more than one conductive pin 61 extends through metal layer 41, the operability of metal layer 41 may be reduced. The inclusion of two discrete reinforced regions may increase the likelihood of warping or shearing of metal layer 41, thereby making fabrication/assembly more difficult.

In addition, the metal layer 41 is typically provided by the manufacturer as a flat sheet or roll of material to transport the flat sheet, while the blade 20 typically includes geometric portions having a three-dimensional shape. Thus, at least some of the metal layer 41 may inevitably warp or stretch due to the complex curvature that is accommodated in the blade mold (e.g., the metal layer 41 may contain areas of increased or decreased density associated with the three-dimensional shape). If the metal layer 41 needs to be aligned with more than one tolerance blade position, for example at more than one conductive pin position, when conforming the plate to a three-dimensional shape, the problem of warpage and/or stretching may undesirably increase. Providing a plurality of smaller discrete metal layer portions ameliorates this problem.

The benefits of providing a metal layer 41 formed of two or more portions may additionally include robustness against process errors and/or manufacturing errors, as only discrete portions of the metal layer 41 need to be repaired or replaced, rather than larger metal layer portions or even the entire metal layer 41.

The plurality of smaller discrete metal layer portions may also allow one or more similarly sized metal layer portions to be used for multiple blade designs (e.g., having different blade lengths or different blade tip geometries). For example, a modular blade design is provided in a series of blades.

Thus, metal layer 41 may be cut/sized such that only the location of a single conductive pin 61 coincides with a particular discrete portion of metal layer 41, i.e., only a single conductive pin 61 extends through each portion 41a,41b of metal layer 41. An example of such an arrangement is shown in fig. 9.

Fig. 9 shows a schematic view of a portion of a lightning protection system comprising a plurality of discrete portions 41a,41b,41c of metal layer 41, and wherein a first conductive pin 61a extends through one of the metal layer portions 41a, but not through any of the other metal layer portions 41b,41 c. Similarly, the second conductive pin 61b extends through one of the metal layer portions 41b but not through any of the other metal layer portions 41a,41 c. This helps to improve the operability of the metal layer portions 41a,41b,41c, since the metal layer portions 41a,41b,41c may each comprise at most one discrete strengthening region.

The operability of the metal layer portions 41a,41b,41c may also be improved by minimizing the size of the metal layer portions 41a,41b,41c, especially when the metal layer portions 41a,41b include reinforcing regions. For example, fig. 9 shows an example in which the first portion 41a and the second portion 41b are separated from the third portion 41c, even though the third portion 41c may not include the reinforcing region. The dimensions of the first portion 41a and/or the second portion 41b may be chosen such that the surface area of the portions 41a,41b is smaller than the largest dimension, e.g. the surface area of each metal layer may be smaller than 20% or smaller than 10% of the total surface area of the wind turbine blade.

While fig. 9 shows the metal layer 41 divided in the spanwise direction such that the discontinuities between each of the first, second and third metal layer portions 41a,41b,41c extend in a substantially chordwise direction, it should be understood that the discontinuities may extend in any direction within the plane of the metal layer.

Fig. 10 shows an example in which the metal layer 41 is divided in a plurality of directions. The discontinuity between the first and second metal layer portions 41a, 41b extends in the generally span-wise direction of the blade 20, while the discontinuity between the third metal layer portion 41c and each of the first and second metal layer portions 41a, 41b extends in the generally chord-wise direction of the blade 20.

Each of the portions 41a,41b,41c may meet at an overlap region 43, wherein one of the portions 41a,41b,41c extends over and overlaps with one of the other adjacent portions 41a,41b,41 c. Fig. 11 shows an example in which the first portion 41a overlaps with a part of the second portion 41b in an overlapping region. The overlap region 43 may help improve electrical connection across the metal layer 41. Although any other suitable arrangement may be used to improve the electrical connection between portions 41a,41b of metal layer 41, for example a third portion of metal layer 41 extends over each of first portion 41a and second portion 41b of metal layer 41.

A method of manufacturing a wind turbine blade comprising at least two conductive pins 61 will now be described with reference to fig. 12A to 12G.

Fig. 12A shows an example of respective blade positions 71a,71b of the conductive pins 61 of the blade 20, which are determined on the blade mould 70. In this example, the blade 20 (or a segment 29 thereof) formed in the blade mold 70 includes two conductive pins 61a,61b: the first conductive pin 61a is located at a first blade position 71a and the second conductive pin 61b is located at a second blade position 71b.

The first portion 41a of the metal layer 41 is laid in the blade mould 70 so as to cover the determined blade position 71a of the first conductive pin 61a and not the determined blade position 71B of the second conductive pin 61B, as shown for example in fig. 12B.

It should be appreciated that multiple layers may be laid onto blade mold 70 prior to first portion 41a of metal layer 41 (and/or second portion 41b of metal layer 41) to form outer surface 52 of blade 20, such as one or more of the following: a fleece layer 58; a gel layer and a lacquer layer 59.

Positioning the first portion 41a of the metal layer 41 in the blade mold 70 may include aligning the first portion 41a of the metal layer 41 with the determined blade position 71a of the first conductive pin 61a, e.g., the first portion 41a of the metal layer 41 may include a pin positioning feature (e.g., a fiducial) that aligns with the determined blade position 71a to ensure accurate positioning of the first portion 41 a. The pin locating feature may be the metal disc 80 and/or the center of the metal disc 80.

The second portion 41b of the metal layer 41 is laid in the blade mould 70 so as to cover the determined blade position 71b of the second conductive pin 61b and not the determined blade position 71a of the first conductive pin 61, as shown for example in fig. 12C. The second portion 41b of the metal layer 41 may be laid in the blade mould 70 such that the edge of the second portion 41b overlaps the edge of the first portion 41a, thereby forming an overlap region 43. The overlap region 43 may help provide the desired electrical connection between the first portion 41a and the second portion 41b across the metal layer 41.

Positioning second portion 41b of metal layer 41 in blade mold 70 may include aligning second portion 41b of metal layer 41 with determined blade position 71b of second conductive pin 61b, e.g., as described with respect to first portion 41 a.

Other portions 41c of metal layer 41 may be laid in blade mold 70. Fig. 12D shows an example of laying a third portion 41c of the metal layer 41 into the blade mould 70. In this case, the third portion 41c does not cover any determined blade positions 71a,71b of the conductive pins 61, and in particular does not cover the first and second conductive pins 61a, 61b shown in the present example. However, it should be appreciated that in alternative examples, the third portion 41c (or subsequent portion) of the metal layer 41 may cover the determined blade position of the further conductive pin 61.

One or more fibrous layers 56 (e.g., dry fibrous preforms or pre-impregnated composite layers) may be laid down on the blade mold 70 on top of the portions 41a,41b,41c of the metal layer 41, as shown, for example, in FIG. 12E.

The blade 20 in the blade mold 70 may then be prepared. This may include: consolidating the fiber layer 56 and the metal layer 41 in the vacuum bag 75, e.g. the fiber layer 56 and the metal layer 41 cover the blade mould 70, including the fiber layer 56 and the metal layer 41; and vacuum pressure is applied through the first valve 76. The fibrous layer 56 may then be cured, for example, under heat and/or pressure. In some examples, the fibrous layer 56 may be a dry fibrous preform or the like, which requires the addition of resin to the blade mold 70. In the example shown in fig. 12F, a second valve 77 for injecting resin is provided. In either case, the resin will integrate both fibrous layer 56 and metal layer 41, thereby forming an integral segment 29 of blade 20.

The cured segment 29 of blade 20 will then be removed from the mold, as shown, for example, in FIG. 12G. The first conductive pin 61a may extend through the first portion 41a of the metal layer 41 and be coupled to the lightning protection system, for example, via the down conductor cable 38. Similarly, a second conductive pin 61b may extend through the second portion 41b of the metal layer 41 and be coupled to the lightning protection system.

In the above example, the surface protection layer 40 comprises a single metal layer 41, wherein any overlap region 43 between adjacent portions 41a,41b,41c of the metal layer has an overlap width of less than 200mm, and typically less than 100mm. However, it should be understood that at least a portion of the surface protection layer 40 may be formed of a plurality of conductive metal layers 41, 42 stacked on each other in the thickness direction of the blade 20. In this case, the metal layers 41, 42 form a multi-thickness region, which may differ from the overlap region 43 between the portions 41a,41b,41c of the metal layer 41 in that the multi-thickness region has a width of at least 200mm and a length of at least 200 mm.

Fig. 13 shows a surface protection layer 40 comprising a first metal layer 41 and a second metal layer 42. The first metal layer 41 and the second metal layer 42 are located on the outer surface of the blade shell and stacked on each other so as to form a multi-thickness region of the surface protection layer 40 in which close electrical contact between the first metal layer 41 and the second metal layer 42 is formed.

The conductive pin 61 may extend through the first and second metal layers 41 and 42. Further, the conductive pins 61 may extend through the disk 80 formed across the metal layers 41, 42. The disk may be formed substantially as described with respect to fig. 8A-8E, wherein the metal disk portions 81a,81b are consolidated to form a single (unitary) metal disk 80 extending through the first and second metal layers 41, 42 such that the first and second metal layers 41, 42 are connected.

Or blade 20 may be formed substantially as described with respect to fig. 12A-12G, wherein the resin integrates fibrous layer 56 and metal layers 41, 42 to form an integral segment 29 of blade 20.

It should be appreciated that the operability of the larger sized plurality of pre-attached metal layers 41, 42 may be reduced as compared to a single metal layer 41, as one or both of the layers 41, 42 may warp or shear or otherwise move out of alignment with the other metal layer 41, 42, and this may make fabrication more difficult. This may provide further excitation to cut the metal layers 41, 42/size the metal layers 41, 42 such that only a single conductive pin 61 is positioned to coincide with a particular discrete portion of the surface protection layer 40 laid in the blade mold 70.

Fig. 14 shows a schematic view of a portion of a lightning protection system comprising a plurality of discrete portions 41a,41b,41c of a first metal layer 41 and a plurality of discrete portions 42a,42b of a second metal layer 42 such that there is a discontinuity between the portions of each metal layer 41, 42. In this arrangement, the first portion 42a of the second metal layer 42 is stacked on the first portion 41a of the first metal layer 41 to form close electrical contact with the first portion 41a of the first metal layer 41. Similarly, the second portion 42b of the second metal layer 42 is stacked on the second portion 41b of the first metal layer 41 to form close electrical contact with the second portion 41b of the first metal layer 41.

In this example, the first conductive pin 61a extends through the first portion 41a of the first metal layer 41 and the first portion 42a of the second metal layer 42, but not through any other metal layer portions 41b,41c,42b. Similarly, second conductive pin 61b extends through second portion 41b of first metal layer 41 and second portion 42b of second metal layer 42, but does not pass through any other metal layer portions 41a,41c,42a. This improves the operability of the metal layer portions 41a,41b,41c,42a,42b, as they may each comprise at most one discrete strengthening region.

It should be noted that while fig. 14 shows portions 42a,42b of second metal layer 42 spaced apart from the perimeter of corresponding portions 41a,41b of first metal layer 41, it should be understood that this is merely illustrative and that portions 42a,42b of second metal layer 42 may also extend to the perimeter of portions 41a,41b of first metal layer 41 or extend beyond the perimeter of portions 41a,41b of first metal layer 41 at various points.

It will be appreciated that first and second metal layers 41 and 42 may be formed of any suitable electrically conductive metal, such as aluminum, copper, stainless steel, brass, or bronze. The first metal layer 41 and/or the second metal layer 42 may be a metal foil. Metal foils can provide benefits in terms of being lightweight while being highly conductive. Further weight saving may be achieved by forming the first metal layer 41 and/or the second metal layer 42 as a metal mesh, a solid foil or an expanded metal foil. First metal layer 41 and/or second metal layer 42 may be any suitable sheet-like conductive material. The sheet used to form first metal layer 41 and/or second metal layer 42 may have a thickness of less than 1mm (alternatively between 0.2mm and 0.6mm, and alternatively between 0.25mm and 0.5mm or between 0.2mm and 0.3 mm). The first metal layer 41 and the second metal layer 42 may have the same thickness or different thicknesses.

The first metal layer 41 and the second metal layer 42 may be formed of the same material. For example, first metal layer 41 and second metal layer 42 may both be aluminum layers. Alternatively, first layer 41 and second layer 42 may be formed of different but complementary materials. For example, one of the layers 41, 42 may be formed of aluminum, while the other layer 41, 42 may be formed of copper. This combination balances the lightweight and inexpensive nature of aluminum with the increased conductivity of copper.

Similarly, the first and second portions of each metal layer 41, 42 may be formed of the same material, or may be formed of different materials. For example, a first portion 41a of first metal layer 41 may be formed of aluminum, while a second portion of second metal layer 41 is formed of copper. This allows the choice of materials in each portion of blade 20 to be determined based on the various requirements (e.g., weight, conductivity, and cost) of balancing blade 20 at each respective portion.

Although the invention has been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope of the invention as defined in the following claims.

Claims (15)

1. A wind turbine blade (20) having a blade shell with a lightning protection system;

the lightning protection system comprises:

a first conductive pin (61 a) and a second conductive pin (61 b) adjacent to the first conductive pin;

A metal layer (40) at an outer surface of the blade shell, the metal layer being divided into a first portion (41 a) and a second portion (41 b) with a discontinuity between the first portion and the second portion;

Wherein the first conductive pin (61 a) extends through a first portion (41 a) of the metal layer and not through a second portion (41 b) of the metal layer; and wherein the second conductive pin (61 b) extends through the second portion (41 b) of the metal layer and not through the first portion (41 a) of the metal layer.

2. A wind turbine blade according to claim 1, wherein the first portion (41 a) and the second portion (41 b) partly overlap to form an overlap region (43).

3. A wind turbine blade according to claim 1 or 2, wherein the wind turbine blade comprises an electrical element, wherein a first portion (41 a) of the metal layer is electrically connected to the electrical element by the first conductive pin (61 a) and a second portion (41 b) of the metal layer is electrically connected to the electrical element (62 a) by the second conductive pin.

4. A wind turbine blade according to any of the preceding claims, wherein the electrical element is a down conductor (38) of the lightning protection system.

5. A wind turbine blade according to any of the preceding claims, wherein the first conductive pin (61 a) extends through a first integral disc (80) formed across the metal layer and/or the second conductive pin (61 b) extends through a second integral disc formed across the metal layer.

6. A wind turbine blade according to any of the preceding claims, wherein the metal layer (40) is a first metal layer (41) and the lightning protection system further comprises a second metal layer (42) at the outer surface of the blade shell, the second metal layer being divided into a first portion (42 a) and a second portion (42 b) with a discontinuity between the first portion and the second portion,

Wherein a first portion (42 a) of the second metal layer is stacked on the first portion (41 a) of the first metal layer to form an intimate electrical contact with the first portion of the first metal layer, and wherein the first conductive pin (61 a) extends through the first portion of the first metal layer and the first portion of the second metal layer; and/or

Wherein a second portion (42 b) of the second metal layer is stacked on the second portion (41 b) of the first metal layer to form a tight electrical contact with the second portion of the first metal layer, and wherein the second conductive pin (61 b) extends through the second portion of the first metal layer and the second portion of the second metal layer.

7. A wind turbine blade according to claims 5 and 6, wherein the first monolithic disc (80) extends through a first portion (41 a) of a first metal layer and a first portion (41 b) of a second metal layer, and/or the second monolithic disc extends through a second portion of the first metal layer and a second portion of the second metal layer.

8. A wind turbine blade according to any of the preceding claims, wherein the first and second portions (41 a, 41 b) of the first metal layer and/or the first and second portions (42 a, 42 b) of the second metal layer are formed of the same material and/or have the same thickness.

9. A wind turbine blade according to claim 6 or 7, wherein the first metal layer (41) and the second metal layer (42) are formed of different materials, or wherein a first part of the first metal layer is formed of a different material than a second part of the first metal layer, or a first part of the second metal layer is formed of a different material than a second part of the second metal layer, preferably wherein the different materials are aluminum and copper.

10. A method of manufacturing a wind turbine blade (20) having a blade shell, the method comprising:

providing a blade mould (70) and providing a metal layer (41) of a lightning protection system of the blade shell, wherein the metal layer is divided into a first part (41 a) and a second part (41 b);

determining respective blade positions of the first conductive pin (61 a) and the second conductive pin (61 b);

-laying a first portion (41 a) of the metal layer in the blade mould so as to cover the determined blade position of the first conductive pin (61 a) but not the determined blade position of the second conductive pin (61 b);

-laying a second portion (41 b) of the metal layer in the blade mould so as to cover the determined blade position of the second conductive pin (61 b) but not the determined blade position of the first conductive pin (61 a).

11. The method of manufacturing a wind turbine blade according to claim 10,

Wherein the step of laying a first portion (41 a) of the metal layer in the blade mould (70) further comprises: aligning pin locating features of a first portion of the metal layer with the determined blade positions of the first conductive pins; and/or

Wherein the step of laying a second portion (41 b) of the metal layer in the blade mould (70) further comprises: pin locating features of a second portion of the metal layer are aligned with the determined blade positions of the second conductive pins.

12. A method of manufacturing a wind turbine blade according to claim 10 or 11, wherein the step of laying the second part (41 b) of the metal layer in the blade mould further comprises: overlapping an edge of the second portion with an edge of the first portion (41 a) to form an overlap region (43).

13. A method of manufacturing a wind turbine blade according to any of claims 10 to 12, the method further comprising:

Extending a first conductive pin (61 a) through a first portion (41 a) of the metal layer and coupling the first conductive pin to a down conductor (38); and/or

A second conductive pin (61 b) is extended through a second portion (41 b) of the metal layer and coupled to a down conductor (38).

14. A method of manufacturing a wind turbine blade according to any of claims 10 to 13, the method further comprising:

-laying the fibre layer (56) of the blade shell in the blade mould (70);

-consolidating the fibre layer and the metal layer (41) in the blade mould and integrating the fibre layer and the metal layer with resin.

15. A method of manufacturing a wind turbine blade according to any of claims 10 to 14, further comprising, before laying the metal layer (41) in the blade mould (70):

providing one or more first metal disc components (81 a,81 b); and heating the one or more first metal disc components to form a first unitary metal disc (80) extending through the first portion (41 a) of the metal layer; and/or

Providing one or more second metal disc components; and heating the one or more second metal disk components to form a second unitary metal disk extending through the second portion of the metal layer.