WO2015055216A1 - Améliorations apportées à des systèmes de protection contre la foudre pour pales d'éoliennes - Google Patents

Améliorations apportées à des systèmes de protection contre la foudre pour pales d'éoliennes Download PDF

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Publication number
WO2015055216A1
WO2015055216A1 PCT/DK2014/050336 DK2014050336W WO2015055216A1 WO 2015055216 A1 WO2015055216 A1 WO 2015055216A1 DK 2014050336 W DK2014050336 W DK 2014050336W WO 2015055216 A1 WO2015055216 A1 WO 2015055216A1
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WO
WIPO (PCT)
Prior art keywords
conductive layer
layer
fabric
blade
fabric layer
Prior art date
Application number
PCT/DK2014/050336
Other languages
English (en)
Inventor
Daniel WHITEHOUSE
Richard Baker
Hassan MENAY
Original Assignee
Vestas Wind Systems A/S
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Vestas Wind Systems A/S filed Critical Vestas Wind Systems A/S
Publication of WO2015055216A1 publication Critical patent/WO2015055216A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03D—WIND MOTORS
    • F03D1/00—Wind motors with rotation axis substantially parallel to the air flow entering the rotor 
    • F03D1/06—Rotors
    • F03D1/065—Rotors characterised by their construction elements
    • F03D1/0675—Rotors characterised by their construction elements of the blades
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/88—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts characterised primarily by possessing specific properties, e.g. electrically conductive or locally reinforced
    • B29C70/882—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts characterised primarily by possessing specific properties, e.g. electrically conductive or locally reinforced partly or totally electrically conductive, e.g. for EMI shielding
    • B29C70/885—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts characterised primarily by possessing specific properties, e.g. electrically conductive or locally reinforced partly or totally electrically conductive, e.g. for EMI shielding with incorporated metallic wires, nets, films or plates
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03D—WIND MOTORS
    • F03D80/00—Details, components or accessories not provided for in groups F03D1/00 - F03D17/00
    • F03D80/30—Lightning protection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
    • H02G13/00—Installations of lightning conductors; Fastening thereof to supporting structure
    • H02G13/80—Discharge by conduction or dissipation, e.g. rods, arresters, spark gaps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2230/00—Manufacture
    • F05B2230/50—Building or constructing in particular ways
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2240/00—Components
    • F05B2240/20—Rotors
    • F05B2240/30—Characteristics of rotor blades, i.e. of any element transforming dynamic fluid energy to or from rotational energy and being attached to a rotor
    • F05B2240/307—Blade tip, e.g. winglets
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/72—Wind turbines with rotation axis in wind direction
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to wind turbine blade structures and associated fabrication processes for improving the resilience of wind turbine blades to lightning strikes.
  • the invention also extends to preformed components for use in such wind turbine blades, and methods for fabricating such preformed components.
  • Wind turbines are vulnerable to being struck by lightning; sometimes on the tower, nacelle and the rotor hub, but most commonly on the blades of the turbine.
  • a lightning strike event has the potential to cause physical damage to the turbine blades and also electrical damage to the internal control systems of the wind turbine.
  • Wind turbines are often installed in wide open spaces which makes lightning strikes a common occurrence. Accordingly, in recent years much effort has been made by wind turbine manufacturers to design wind turbines so that they are able to manage effectively the energy imparted to them during a lightning strike in order to avoid damage to the blade and the cost associated with turbine down-time during blade replacement.
  • an electrically conductive lightning receptor element is arranged on an outer surface of the blade to receive a lighting strike. Since the receptor element is electrically conductive, lightning is more likely to attach to the receptor element in preference to the relatively non-conductive material of the blade.
  • the receptor element is connected to a cable or 'down conductor' that extends inside the blade to the root and from there connects via an armature arrangement to a charge transfer route in the hub, nacelle and tower to a ground potential.
  • Such a lightning protection system therefore allows lightning to be channelled from the blade to a ground potential safely, thereby minimising the risk of damage.
  • the discrete receptors are relatively complex to install during fabrication of the blade and, moreover, they leave a significant portion of blade area exposed to a risk of lightning strike.
  • Such a receptor arrangement provides discrete conductive points to which lightning may attach.
  • US2011/0182731 describes a wind turbine blade having a conductive layer that is laid over the outer surface of the blade shell so as to make contact with the receptor elements. The conductive layer increases the area of the blade that can receive lightning, thereby increasing the rate at which the receptor elements can capture lightning strikes safely.
  • a conductive layer used in this way can be said to increase the capability of the lightning protection system to intercept lightning strikes, such a system can be complex to manufacture since the conductive layer must be added to the blade after the blade shell has been fabricated. This requires an additional time-consuming manufacturing step thereby increasing assembly time and cost.
  • the invention provides a method of fabricating a pre-formed component of a lightning protection system for a wind turbine blade, the method comprising: providing a first fabric layer; applying a conductive layer to the first fabric layer; and applying a second fabric layer so as to sandwich the conductive layer between the first and second insulating layers.
  • the conductive layer extends a predetermined area of the blade surface and may be a relatively thin foil or an aperture foil, such as a mesh, expanded metal foil and the like.
  • the conductive layer may be applied in a single sheet or, alternatively, it may be applied as a plurality of conductive layer portions which are arranged on the first fabric layer with respect to one another to define one or more regions or margins of overlap.
  • the overlapping regions may be arranged to define a network of current carrying channels across the conductive layer so that energy from a lightning strike that attaches to the conductive layer is conducted along the relatively high capacity channels. This makes the conductive layer more robust and less likely to suffer damage.
  • the method may further include forming one or more reinforced zone in the conductive layer.
  • the advantage of the reinforced zone is that it provides a robust connection point for an electrical connection to be made between the conductive layer and down conducting system of an associated blade.
  • a first metallic element may be applied to a first side of the conductive layer in the respective zone.
  • the metallic element may be used to thicken the conductive layer locally within the zone, for example using a soldering or brazing process.
  • the metallic element may be a solid metallic member such as disc or plate that is suitably connected to the conductive layer, by welding or brazing, for example, such that the metallic element is fused to the conductive layer so as to become integral therewith.
  • a second metallic element may be provided on the other side of the conductive layer so that it is in registration with the first metallic element in the reinforced zone.
  • the method may include forming one or more apertures in the first fabric layer corresponding to the respective reinforced zone so that the underlying conductive layer is exposed.
  • the method may also include applying a forming element to the conductive layer with respect to the or each of the reinforced zones.
  • the forming element may be positioned so as to define a recess above its associated reinforced zone for receiving an electrical component when installed in a blade lay up.
  • a head of a receptor bolt may be received in the recess such that an upper surface of the head lies flush with the outer blade surface.
  • the first and second fabric layers are suitable for use for composite manufacture so may be carbon fibre fabric. However, preferably, the fabric layers comprise glass fibre fabrics. Each may have a similar or dissimilar weights so as to meet the requirements of the surface formed on each side of the conductive layer.
  • the fabric layers may be joined to the conductive layer by stitching. Alternatively, or in addition, the fabric layers may be tackified either before applying the conductive layer or they may be supplied pre-tackified.
  • the method of the invention produces a component that can be used in fabricating a wind turbine blade. Therefore, in a second aspect, the invention resides in a preformed component of a lightning protection system for a wind turbine blade comprising a conductive layer sandwiched between a first fabric layer and a second fabric layer.
  • Figure 1 is a plan view of a wind turbine blade equipped with a lightning protection system
  • Figure 2 is an enlarged view of a region of the turbine blade in Figure illustrates a surface protection layer of the lightning protection system
  • Figure 3 is a section through a leading edge region of the turbine blade in Figure 2 along the line C-C;
  • Figure 4 is a section through a trailing edge region of the turbine blade in Figure 2 along the line C-C;
  • Figure 5 is an enlarged perspective view of a surface protection layer in exploded format
  • Figure 6 is an enlarged view of the region A indicated on Figure 3;
  • Figure 7a to 7e illustrate a series of fabrication steps for a wind turbine blade shell incorporating a surface protection layer
  • Figures 8a to 8d illustrate series of fabrication steps for a preformed component of a surface protection layer. Detailed description
  • a wind turbine blade 2 incorporates a lightning protection system 3.
  • the blade 2 is formed from a blade shell 4 having two half-shells.
  • the half- shells are typically moulded mainly from glass-fibre reinforced plastic (known as 'GFRP' or, simply 'GRP') that comprises glass fibre fabric embedded in a cured resin matrix.
  • 'GFRP' glass-fibre reinforced plastic
  • the precise construction of the blade shell 4 is not central to the invention and so further detailed description is omitted for clarity.
  • the blade comprises a root end 6, at which the blade 2 would be attached to a rotor hub of a wind turbine, a tip end 8, a leading edge 10 and a trailing edge 12.
  • a first surface 14 of the blade 2 defines an aerodynamic profiled surface that extends between the leading edge 10 and the trailing edge 12.
  • the blade 2 also includes a second surface also extending between the leading edge 10 and trailing edge 12, which is not shown in the plan view of Figure 1 , but which is indicated as reference numeral 16
  • the surface 16 of the blade 2 When the blade 2 is attached to a rotor hub of a wind turbine, airflow strikes the surface 16 of the blade 2 and for this reason the surface 16 is also referred to as a 'pressure side' or 'windward side' in the art. Conversely, the surface 14 is referred to as the
  • the blade 2 is divided into three zones for the purposes of lightning protection - these are illustrated in Figure 1 as zones A, B and C.
  • the lightning protection apparatus that is used in each of the zones is selected based on a set of lightning strike parameters, such as peak current amplitude, impulse current, specific energy, impulse shape and total charge that the blade 2 is expected to withstand in each of the zones.
  • Zone A extends from the root end 6 of the blade to approximately 60% of the blade length in the span-wise direction.
  • the blade 2 has a low risk of a lightning strike and so will be expected to receive a low incident of strikes at low current amplitudes, and low total charge transfer, which is acceptable for blade structural impact.
  • the blade 2 is not equipped with any external lightning protection within this zone.
  • Zone B extends from the end of zone A to approximately 90% of the blade length in a span-wise direction.
  • the blade 2 has a moderate risk of lightning strike and is expected to withstand moderately frequent direct lightning strike attachments having increased impulse current, peak current and total charge transfer.
  • the blade 2 is provided with a first lightning protection sub-system 20 in the form of a surface protection layer 20.
  • zone C extends from the end of zone B to the tip end 8 of the blade 2.
  • the blade 2 is subject to a high likelihood of lightning strikes and is expected to withstand peak current amplitudes of in excess of 200kA and total charge transfer in excess of 300 coulomb and, moreover, a high incident of strikes.
  • zone C includes two further lightning protection subsystems. Firstly, there is provided an array of receptors (hereinafter 'receptor array') 22 and, secondly, there is provided a blade tip assembly 24.
  • 'receptor array' an array of receptors 22 and, secondly, there is provided a blade tip assembly 24.
  • Both the receptor array 22 and the blade tip assembly 24 are electrically connected to a down conducting system 26, comprising first and second down conductors 28, 30 running along the length of the blade 2 from the tip end 8 to the root end 6, generally being arranged adjacent the leading edge 10 and trailing edge 12 of the blade 2, respectively.
  • a down conducting system 26 comprising first and second down conductors 28, 30 running along the length of the blade 2 from the tip end 8 to the root end 6, generally being arranged adjacent the leading edge 10 and trailing edge 12 of the blade 2, respectively.
  • the surface protection layer 20 is in zone B and comprises a conductive layer that is integrated into both the upper half-shell and the lower half-shell of the blade 2.
  • the conductive layer may be a metallic screen or mesh, and preferably a mesh/screen in the form of an expanded metal foil that acts to attract lightning strikes over a large area of the blade and which is connected to the down conducting system 26 in a manner that will be described.
  • the thickness of the conductive layer is such that the aerodynamic profile of the blade 2 is unaffected and so it is preferred that the conductive layer is less than 5mm in thickness. It is currently envisaged that the conductive layer is less than 1 mm in thickness, preferably 0.3mm.
  • FIG. 2 shows the surface protection layer 20 in more detail, although not to scale.
  • the surface protection layer 20 is connected to the down conductors 28, 30 by a plurality of connector arrangements 40.
  • Four connector arrangements 40 are shown in this view of the surface of the blade 2, two being adjacent the leading edge 10 of the blade and two being adjacent the trailing edge 12 of the blade 2.
  • Figure 3 shows a leading edge connector arrangement 40 in more detail and Figure 4 shows a trailing edge connector arrangement 40 in more detail.
  • the connector arrangement 40 includes a block-like connector component 42 that is shaped to fill the volume in the relatively deep profile of this region of the blade 2 and provide an electrical connection to a first connector element 44 associated with the leeward surface 14 and a second connector element 46 associated with the windward surface 16.
  • the connector component 42 comprises first and second connector bases 48, 50 that are encapsulated by an insulating member 52 that is generally annular in form.
  • the insulating member 52 is moulded directly to the connector bases 48, 50 and so serves to suppress the initiation of ionization and streamers during highly charged environmental conditions, which thereby guards against a lightning strike directly onto the connector bases 48, 50 rather than on a connector element 44, 46.
  • the insulating member 52 is formed of a suitable polymer having a high dielectric strength, and it is envisaged that the insulating member will be polyurethane for its good dielectric properties and low cost, although other insulating materials are acceptable.
  • the insulating member 52 is generally C-shaped, and is defined by first and second arm portions 52a, 52b that extend from each end of a yoke portion 52c.
  • Each of the connector bases 48, 50 is encapsulated by a respective one of the arm portions 52a, 52b and in this manner the connector bases 48, 50 are located in a predetermined position against a respective leeward 14 and windward surface 16 of the blade 2.
  • the connector bases 48, 50 are conductive, preferably brass for its high conductivity, corrosion resistance, and drillability although other metals or alloys would be acceptable.
  • the first connector element 44 electrically couples the surface protection layer 20 on the leeward surface 14 to the first connector base 48.
  • the second connector element 46 couples the surface protection layer 20 on the windward surface 16 to the second connector base 50.
  • the connector elements 44, 46 are identical so only one of them shall be described in detail.
  • the first connector element 44 is in the form of a bolt having a head 44a and a shank 44b. Stainless steel is currently the preferred material for the bolt, although other conductive materials, particularly metals, are also acceptable.
  • the shank 44b extends through the blade 2 and engages with the first connector base 48 by way of cooperating screw threads, and the head 44a is arranged to lie flush with the surrounding surface of the surface protection layer 20. Note that the underside of the head 44a is substantially flat so as to establish a robust electrical connection with the surface protection layer 20.
  • An identical arrangement is provided to couple the surface protection layer 20 on the windward surface 16 to the second connector base 50.
  • a conductive link 56 is provided to electrically connect the first connector base 48 to the second connector base 50 and, in this embodiment, the conductive link 56 is a zinc coated copper braided wire.
  • braided wire is not essential, it is useful from a manufacturing perspective since it is flexible and so can be suitably shaped to extend between the first and second connector bases 48, 50 prior to encapsulation by the insulating member 52.
  • Connection between the connector component 42 and the down conducting system 26 is made by welding the second connector base 50 to a corresponding down conductor, which as illustrated is the first down conductor 28 near the leading edge 10 of the blade 2.
  • the conductive link 56 and the down conductor 28 may be arranged in a predetermined pattern with respect to the first and second connector bases 48, 50 and connected thereto by, for example, exothermic welding to ensure the electrical integrity of the connection prior to casting the insulating member 52 around the components.
  • the connector component 42 becomes installable as a unit together with the down conducting system 26.
  • the insulating member 52 is sandwiched between an interior of the leeward surface 14 and an interior of the windward surface 16.
  • Adhesive (not shown) is located between the insulating member 52 and the interiors of the leeward and windward surfaces 14, 16 to bond the insulating member to the interior of the blade.
  • Figure 3 shows a cross section through the insulating member 52 and that the first connector base 48, the second connector base 50 and the conductive link 56 are fully encapsulated by the insulating member 52.
  • the insulating member 52 may have a width in the span-wise direction of around 15 cm.
  • the connector arrangement 40 shown in Figure 4 also includes a block-like connector component 60 that connects to a first connector element 62 associated with the leeward surface 14 and a second connector element 64 associated with the windward surface 16.
  • the connector component 60 comprises a single connector base 63 with which the connector elements 62, 64 engage, and an insulating member 66 that encapsulates the connector base 63.
  • the connector base 63 includes a corresponding recess 68 through which the trailing edge down conductor 30 is routed so as to connect the connector bases 63 into the down conducting system 26. Therefore, the encapsulation of the connector base 63 also encapsulates the junction between the down conducting system 26 and the connector base 63.
  • Each connector element 62, 64 is in the form of a bolt having a head 62a, 64a and a shank 62b, 64b.
  • the shanks 62b, 64b extend into the blade 2 and engage into a threaded socket 70 in the connector base 63.
  • the heads 62a, 64a lie against and are countersunk into the blade shell so that an upper face of the heads 62a, 64a are flush with the surrounding surface of the blade 2.
  • the connector component 60 is installed in region of the blade 2 that has a relatively shallow depth, preferably the connector elements 62, 64 are joined to the connector base 63 so as to be offset from one another or 'staggered', as is shown in Figure 4. This avoids the shanks 62b, 64b of opposing connector elements 62, 64 contacting one another when installed.
  • the insulating member 66 is sandwiched between an interior of the leeward surface 14 and an interior of the windward surface 16. Adhesive (not shown) is located between the insulating member 66 and the interiors of leeward and windward surfaces 14, 16 to bond the insulating member to the interior of the blade.
  • Figure 4 shows a cross section through the insulating member 66 and that the connector base 63 is fully encapsulated by the insulating member 66.
  • the insulating member 66 may have a width in the span-wise direction of around 15 cm.
  • the head of the connector elements 44, 46, 62, 64 defines an electrical coupling or interface between the surface protection layer 20 and the respective connector component 42, 60.
  • the surface protection layer 20 and, in particular, the electrical connection between it and the connector elements will now be described with reference to Figures 5 and 6.
  • the surface protection layer 20 incorporates a conductive layer currently envisaged to be expanded aluminium foil.
  • the surface protection layer 20 is shown in exploded view for clarity against a blade mould surface portion 80.
  • the surface protection layer 20 includes three main components: an outer insulating layer 82, an inner insulating layer 84 and a conductive layer 86 sandwiched between the insulating layers 82, 84. Both the outer insulating layer 82 and the inner insulating layer are glass fibre fabric.
  • the outer insulating layer 82 becomes the outer surface or skin of the blade 2 once the blade 2 is fully fabricated.
  • the outer insulating layer 82 is a relatively lightweight fabric, for example less than 200gsm, so as not to inhibit the formation of leaders from the conductive layer 86 during lightning conditions.
  • the thin outer layer also reduces the risk of surface damage during a strike.
  • the weight of the inner insulating layer 84 is heavier, for example around 600gsm, although these values should not be considered limiting.
  • the conductive layer includes reinforced zones, identified in Figure 5 generally as '90'. The reinforced zones 90 serve to strengthen the conductive layer 86 in localised regions by thickening the metal foil in some way.
  • the conductive layer 86 may undergo a soldering or casting process to solidify the expanded foil in localised regions.
  • one or more conductive elements in the form of plates, discs or the like are bonded to the conductive layer 86 in the required zones. Bonding may be by way of brazing for example.
  • a forming element 92 is applied to the outer insulating layer 82 prior to the lay down of the conductive layer 86.
  • the forming element shapes the conductive layer 86 during blade fabrication to provide a recess for receiving a respective connector element, as will now be described with reference to Figure 6 which is an enlarged view of region 'A' in Figure 3 and so shows the surface protection layer 20 in situ.
  • the insulated forming element also prevents unwanted lightning strike attachment points adjacent to the connector bolts, thus preventing the surface protection layer from being damaged.
  • the surface protection layer 20 is shown as defining the leeward surface 14 of the blade 2 together with a set of structural blade components 96 with which the surface protection layer 20 is integrated during a resin infusion and curing process.
  • the structural blade components 96 may include further fabric layers, foam core sections and the like, as would be known to a person skilled in turbine blade design.
  • the insulating member 52 is bonded to the structural blade components 96 by a layer of adhesive (not shown).
  • the forming element 92 is an outwardly-tapered annular disc that includes an inner aperture 98 defining an inner wall 100.
  • the forming element is preferably a polymeric part, particularly polyurethane.
  • the forming element 92 sits in-board of the outer insulating layer 82 such that the layer 82 extends over a flat outer face 92a of the forming element 92 and terminates at an aperture 101 aligned with the inner wall 100. Note, however, that the outer insulating layer 82 may instead terminate at the outer edge of the forming element 92.
  • the conductive layer 86 is in-board of the outer insulating layer 82 and is positioned such that a reinforced zone 90 thereof is in registration with, or 'superimposed' on, the aperture 98 of the forming element 82.
  • the reinforced zone 90 includes first and second metal discs 102 that are cast onto either side of the conductive layer 86.
  • the dished or domed shape of the forming element 92 raises the level of the reinforced zone 90 so that it defines a recessed base 104 adjacent the inner wall 100 of the forming element 92.
  • the recess defined by the base 104 and the inner wall 100 has a depth that matches with the depth of the head 44a of the connector element 44.
  • the underside of the head 44a abuts the reinforced zone 90 and the upper face of the head 44a lies substantially flush with the surrounding blade surface 14.
  • the faying surfaces thereof may be machined to an appropriately fine surface finish. This helps to avoid arcing during current transfer between the conductive layer 86 and the connector element 44.
  • the shank 44b of the connector element 44 extends through a bore 103 provided through the reinforced zone 90 and the structural components 96 so as to engage with the connector base 48 of the connector element 52 that is mounted adjacent the inside surface of the blade 2.
  • the surface protection layer 20 could be built up in a step-by-step process during fabrication of the blade 2 or, alternatively, the surface protection layer 20 could be provided as a preformed component that can be laid-up as a unit onto a blade mould.
  • a blade mould 109 having a surface 1 10 is provided as an initial step.
  • a blade mould is typically provided as two mould halves in which two half shells are formed. Once the half shells have been fabricated, the two mould halves are brought together and the half shells are joined thus completing the shell of the blade 2.
  • the outer insulating layer 82 and the forming element 92 are provided on the mould surface.
  • the outer insulating layer 82 has an aperture 101 that lines up with the inner wall 100 of the forming element 92.
  • the forming element 92 includes a plug member 1 12 that sits tightly inside the aperture 98 of the forming element 92.
  • the plug member 112 is preferably a polymeric part and serves two main purposes. Firstly, it defines the position of the recessed base 104, as shown in Figure 6, and so for this reason it has substantially the same shape and dimensions as the head 44a of the connector element 44.
  • the conductive layer 86 is shown laid-up on the forming element 92. It will be appreciated that the majority of the conductive layer 86 is substantially planar, although the (or each) forming element 92 shapes a localised region of the conductive layer 86, and particularly the reinforced zone 90 over its outer profile. Here it can be seen that one of the conductive discs 102 of the reinforced zone sits onto the plug member 1 12 thereby defining the recessed base 104 of the inner wall 100. Note that the conductive layer 86 has been provided as a preformed component with the conductive discs 102 pre-cast onto appropriate regions.
  • the inner insulating layer 84 is laid down on top of the conductive layer 86.
  • the inner insulating layer may be provided with a tackified surface so that it adheres to the conductive layer 86 prior the resin infusion process.
  • the half shell is laid-up by arranging the structural components 96 over the surface protection layer 20, as is illustrated in Figure 7e.
  • the structural components are shown here schematically and may include one or more glass fibre fabric layers, foam cores or spar caps.
  • the whole lay up is covered with an airtight bag that forms a sealed region over the components.
  • the sealed region may then be evacuated using a vacuum pump, following which liquid resin is introduced into the sealed region so that it may flow through a series of channels to allow the resin to infuse completely through the lay up.
  • the vacuum pump continues to operate during the subsequent curing process in which the mould may undergo controlled heating to cure the blade half shell effectively.
  • the component layers of the surface protection layer 20 are fixed in position and, in particular, the reinforced region 90 is set as the recessed base 104 of the aperture 98.
  • the plug member 1 12 is removed, thereby exposing the underlying reinforced zone 90 of the conductive layer 86.
  • its position may be recorded so that it is readily locatable once the moulding is complete.
  • the plug member 1 12 may incorporate an appropriate locator mechanism 120 which in this embodiment is a magnet 120 encased within the plug member 112.
  • the connector element 44 may be inserted through a suitable bore drilled through the half shell so as to connect up to as associated connector arrangement 40, as is shown in Figure 6.
  • Manufacturing benefits may be achieved by forming the first and second insulating layers 82, 84 and the conductive layer 86 as a preformed component, as will now be explained with reference to Figures 8a to 8d. The same reference numerals will be used for consistency.
  • the conductive layer 86 has been illustrated as a single sheet.
  • the conductive layer 86 is shown as a pattern of rectilinear conductive layer portions, indicated generally as 202, arranged to be overlapped with one another, as will be explained.
  • the pattern of conductive layer portions 202 includes two main portions 202a and two side portions 202b.
  • Each of the portions 202a, 202b includes first and second folded end regions 204.
  • the folded end regions 204 serve to avoid any loose ends protruding from the expanded metal foil and increases current carrying capacity.
  • the corners of the conductive layer portions may be formed with a radius to avoid sharp corners which may otherwise be vulnerable to lightning attachment.
  • the two main portions 202a are provided with a reinforced region 90 at each of their folded ends, resulting in four reinforced regions 90 in total.
  • the reinforced regions 90 may be formed by casting metallic discs onto the main portions 202 in the manner described above with reference to Figures 7a-7e.
  • the pattern of conductive layer portions 202 are to be overlaid on a first insulating layer 82 which, as has been described above, is a glass fibre fabric. Since this layer 82 will form the outermost skin of the blade, preferably this fabric layer is relatively lightweight to avoid suppression of lightning leaders emanating from the conductive layer and to minimize surface damage during a strike 86.
  • the first insulating layer 82 is provided with four forming elements 92 located in positions so that they overlay the apertures 98 in the insulating layer 82. As an alternative to this, the forming elements 92 may be applied directly to the reinforced regions 90 on the conductive layer 86 so that they are superimposed thereon.
  • the pattern of conductive layer portions 202 are then overlaid on the first insulating layer 82 in an overlapping manner. Firstly, the two main portions 202a are overlapped slightly with one another along their long edges, in the order of a few centimetres, to define a central margin of overlap 208. Then, the two side portions 202b are overlaid either partially or completely on the outer long edges of the main portions 202a, which provides two outer margins of overlap 210.
  • the assembled conductive layer 86 may then be stitched in place on the first insulating layer 82 to ensure that it is held securely in position.
  • the first insulating layer 82 may be provided with a tackified surface so that the conductive layer portions 202 self-adhere to the first insulating layer 82.
  • the surface of the first insulating layer 82 may be tackified by the application of a suitable pressure sensitive adhesive. Tackified glass fibre fabrics are available commercially.
  • the channel 212 extends about the perimeter of the conductive layer 86, and also longitudinally through the centre of the layer 86.
  • the channel 212 is beneficial in directing the energy from a lightning strike from the relatively thin regions of the conductive layer 86 along the channel 212 and to the reinforced regions 90 at which points the conductive layer 86 is coupled to the down conductive system 26 via the connector elements as discussed above.
  • a second insulating layer 84 is applied on top of the conductive layer 86 so as to sandwich the conductive layer 86 between it and the first insulating layer 82.
  • the second insulating layer 84 may be stitched to the first insulating layer 82 and/or the conductive layer 86 in order to secure all of the layers together.
  • the faying surface of the second insulating layer 84 may also be tackified with a suitable adhesive.
  • the surface protection layer 20 is equipped with measures to make it able to manage frequent high energy lightning strikes.
  • the reinforced regions 90 strengthen the conductive layer 86 in regions where it connects to the down conductor system 26.
  • the current channel 212 provides a means to manage the energy flow path through the conductive layer 86 which increases the robustness of the conductive layer.
  • the preforming process as described above could also be applied to a more simple surface protection layer 20 including a single sheet of metallic conductor, expanded metal foil, for example, sandwiched between first and second glass fibre fabric layers.
  • the specific embodiment of the surface protection layer 20 is shown as having four points of contact between it and the down conducting system 26 of the blade 2. This is driven in part by the fact that the down conducting system 26 includes two down conductors 28, 30 that run the length of the blade near to the leading and trailing edges.
  • the surface protection layer 20 may be provided with less than four points of contacts. One or two points of contact may be sufficient in the case where the blade is provided with a single down conductor.
  • the forming element 92 has been described above as having a plug element 112 which incorporates a magnet which assists technicians in locating the forming element after the blade has been removed from its mould. It will be appreciated that this is one way to provide the forming element with locating means, and that other ways are possible. For example, a simple metallic inset could be located by a suitable hall sensor, for example. Other means include the use of RF transponders. Furthermore, it will be appreciated that the locating means could be incorporated into the outer part of the forming element instead of the plug member.
  • the blade is divided into three zones, A, B, and C, for the purposes of lightning protection. It will be appreciated that this is merely an example of how a blade may be configured for lightning protection and is not intended to be limited. For example, a blade may be configured so that zone A is omitted. In effect, therefore, the blade is protected along its entire length instead of leaving a zone relatively unprotected from lightning strikes.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Combustion & Propulsion (AREA)
  • General Engineering & Computer Science (AREA)
  • Composite Materials (AREA)
  • Wind Motors (AREA)

Abstract

La présente invention concerne un procédé de fabrication d'un élément préformé d'un système de protection contre la foudre pour une pale d'éolienne, le procédé consistant à fournir une première couche de tissu; à appliquer une couche conductrice sur la première couche de tissu; et à appliquer une seconde couche de tissu de sorte à prendre en sandwich la couche conductrice entre les première et seconde couches isolantes. L'invention concerne également un élément préformé d'un système de protection contre la foudre pour une pale d'éolienne comprenant une couche conductrice prise en sandwich entre une première couche de tissu et une seconde couche de tissu.
PCT/DK2014/050336 2013-10-17 2014-10-15 Améliorations apportées à des systèmes de protection contre la foudre pour pales d'éoliennes WO2015055216A1 (fr)

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GB1318384.3A GB2519333A (en) 2013-10-17 2013-10-17 Improvements relating to lightning protection systems for wind turbine blades
GB1318384.3 2013-10-17

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WO2015055216A1 true WO2015055216A1 (fr) 2015-04-23

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US20150292487A1 (en) * 2014-04-10 2015-10-15 Nordex Energy Gmbh Wind turbine rotor blade having a lightning receptor base and method for making the same
EP4019766A1 (fr) * 2020-12-23 2022-06-29 Polytech A/S Connexion conductrice
EP3869035B1 (fr) 2020-02-21 2022-11-30 Siemens Gamesa Renewable Energy Innovation & Technology, S.L. Pale pour un rotor d'éolienne et son procédé de fabrication
CN117962355A (zh) * 2024-04-02 2024-05-03 成都飞机工业（集团）有限责任公司 一种蜂窝夹芯复合材料的成型方法

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DE102017114151A1 (de) * 2017-06-26 2018-12-27 Eno Energy Systems Gmbh Blitzschutzsystem für ein Rotorblatt
EP4368833A1 (fr) * 2022-11-14 2024-05-15 Siemens Gamesa Renewable Energy Innovation & Technology S.L. Pale d'éolienne

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US20130078105A1 (en) * 2010-05-21 2013-03-28 Stephan Drewes Rotor blade for a wind turbine
WO2013084634A1 (fr) * 2011-12-09 2013-06-13 三菱重工業株式会社 Éolienne et dispositif de production d'énergie éolienne

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US20040130842A1 (en) * 2000-04-10 2004-07-08 Johansen Oluf Peter Kaad Lightning protection system for, e.g. a wind turbine, wind turbine blade having a lightning protection system, method of creating a lightning protection system and use thereof
WO2003008800A1 (fr) * 2001-07-19 2003-01-30 Neg Micon A/S Aube d'eolienne
US20130078105A1 (en) * 2010-05-21 2013-03-28 Stephan Drewes Rotor blade for a wind turbine
WO2013084634A1 (fr) * 2011-12-09 2013-06-13 三菱重工業株式会社 Éolienne et dispositif de production d'énergie éolienne

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US20150292487A1 (en) * 2014-04-10 2015-10-15 Nordex Energy Gmbh Wind turbine rotor blade having a lightning receptor base and method for making the same
US10199816B2 (en) * 2014-04-10 2019-02-05 Nordex Energy Gmbh Wind turbine rotor blade having a lightning receptor base and method for making the same
EP3869035B1 (fr) 2020-02-21 2022-11-30 Siemens Gamesa Renewable Energy Innovation & Technology, S.L. Pale pour un rotor d'éolienne et son procédé de fabrication
EP4019766A1 (fr) * 2020-12-23 2022-06-29 Polytech A/S Connexion conductrice
WO2022136632A1 (fr) * 2020-12-23 2022-06-30 Polytech A/S Liaison conductrice
CN117962355A (zh) * 2024-04-02 2024-05-03 成都飞机工业（集团）有限责任公司 一种蜂窝夹芯复合材料的成型方法

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GB201318384D0 (en) 2013-12-04

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