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
  • F03D80/00—Details, components or accessories not provided for in groups F03D1/00 - F03D17/00
  • F03D80/30—Lightning protection
• • 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
  • F03D13/00—Assembly, mounting or commissioning of wind motors; Arrangements specially adapted for transporting wind motor components
  • F03D13/10—Assembly of wind motors; Arrangements for erecting wind motors
• • 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
• • 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

Definitions

• the present invention relates to a side receptor for a lightning protection system for a wind turbine blade.
• Most known lightning protection systems for wind turbine blades comprise one or more internally arranged down conductors and a number of lightning receptors arranged on the external surface of the blade.
• a tip receptor arranged at the tip of the wind turbine blade and a number of side receptors distributed on the surface of the wind turbine blade along at least a part of the length thereof.
• a typical side receptor as known in the art simply consi sts of a metal bolt, the head of which is aligned with the external surface of the wind turbine blade and the thread part of which i s screwed into a side receptor base arranged within the wind turbine blade.
• the electrically conducting side receptor base is electrically grounded so that the current from lightning strikes impacting the head of the side receptor passes through the thread part thereof to the side receptor base and further through the wind turbine blade and the wind turbine tower to the ground.
• a number of problems are related to the use of such typical side receptors.
• the head of the side receptor is often damaged by the impacts of lightning strikes. This means that any recesses (slots) or other structural elements in the head meant for engagement by tools may have at least partly disappeared after a number of lightning impacts. Therefore, it is often more or less impossible to unscrew the side receptor, for instance in order to replace it. Ironically, the more a replacement of a side receptor is needed, the more difficult it may be to remove it.
• the present invention relates to a side receptor for a lightning protection system for a wind turbine blade, which side receptor comprises a receptor cylinder, a mounting bolt and a receptor plug, wherein the receptor cylinder is a tubular metallic part with one partly closed end penetrated by a centred hole, at least a part of the external surface of which partly closed end is arranged to be a contact surface for mechanical and electrical contact to a side receptor base when the side receptor is mounted within a wind turbine blade, and the diameter of which centred hole is slightly larger than the diameter of the thread part of the mounting bolt, wherein the inner diameter of the receptor cylinder i s larger than the diameter of the head of the mounting bolt and the internal length of the receptor cylinder is larger than the height of the head of the bolt so that the mounting bolt can be arranged with its head concealed within the receptor cylinder and its thread part protruding through the centred hole in the partly closed end thereof, and wherein the receptor plug is dimensioned to fit into the end of the receptor cylinder opposite
• Another advantage is that the lightning current passes through the contact surface rather than through the threads of the mounting bolt and that, therefore, there are no problems related to using threadl ockers or other adhesives for securing the mounting bolt and thereby the side receptor.
• the receptor plug is made from a solid material, such as a metal, a plastic material or fibreglass.
• the solid plug may be drilled out, when the side receptor has to be replaced and access to the mounting bolt is needed.
• the receptor plug consists of a heat resistant paste, such as silicone.
• a screw cap made for instance by High-density polyethylene (HDPE), is arranged w ithin the slot of the mounting bolt.
• HDPE High-density polyethylene
• Placing a screw cap within the slot of the mounting bolt protects the slot and ensures that it is not filled by paste, from which the receptor plug may be formed, which could be troublesome when a tool has to engage with this slot for loosening and remov al of the mounting bolt.
• the side receptor further comprises a washer to be arranged between the head of the mounting bolt and the internal surface of the partly closed end of the receptor cylinder.
• the side receptor further comprises around the head of the mounting bolt a bolt insulator, made for instance from polymers or insulating composites (fibreglass or Bakelite), for insulating the mounting bolt electrically from the receptor cylinder.
• the thread diameter of the mounting bolt is between 8 mm and 15 mm, preferably between 10 mm and 12 mm.
• the outer edge of the receptor cylinder at the partly closed end thereof is bevelled so that at least a part of the contact surface is slanted.
• the angle between the bev elled part of the contact surface and the longitudinal axis of the receptor cylinder is between 30° and 70°, preferably between 55° and 65°, most preferred 59°.
• the use of an at least partly slanted contact surface ensures a better mechanical contact and results in a larger contact surface for passage of the lightning current from the side receptor to the side receptor base.
• An angle of 59° corresponds to the shape of the end of a standard drill .
• the side receptor further comprises at its end opposite the partly closed end a receptor ruff protruding outwards substantially perpendicularly to the longitudinal axis of the receptor cylinder.
• a receptor ruff helps ensuring a tight connection between the side receptor and the surrounding surface of the wind turbine blade and ensures more material for the arc root erosion due to lightning impacts.
• the receptor cylinder consists at least partly of copper or a copper alloy. The use of copper ensures a very high electric conductivity and a high thermal conductivity of the receptor cylinder.
• the receptor cylinder consists at least partly of steel .
• the receptor cylinder consists at least partly of aluminium.
• the receptor cylinder at its end opposite the partly closed end is covered with a protective layer of a temperature-resistant material, such as tungsten carbide.
• the receptor cylinder consists at least partly of tungsten carbide.
• tungsten carbide ensures a high electric conductivity, a high thermal conductivity and a very high melting temperature of the surface of the receptor cylinder and, hence, low susceptance to charge erosion from lightning strikes.
• the inner diameter of the receptor cylinder is between 10 mm and 40 mm, preferably between 1 5 mm and 30 mm.
• the wall thickness of the receptor cylinder is between 2 mm and 10 mm, preferably between 4 mm and 8 mm. In an embodiment of the invention, the length of the receptor cylinder is between 1 5 mm and 150 mm, preferably between 20 mm and 50 mm.
• the side receptor further comprises a blade surface protection surrounding the receptor cylinder and extending outwards therefrom in a plane substantially perpendicular to the longitudinal axis thereof being substantially aligned with the end of the receptor cylinder opposite the partly closed end and, if present, with the receptor ruff.
• the blade surface protection i s made from a circular sheet of a heat-resistant plastic material, such as a polyester or polyamide film, fibreglass composite materials or high temperature ceramic compounds, which is fastened to the surface of the wind turbine blade by means of an adhesive.
• a heat-resistant plastic material such as a polyester or polyamide film, fibreglass composite materials or high temperature ceramic compounds
• a lightning protection system for a wind turbine blade comprising one or more side receptors as described above.
• Fig. 1 illustrates schematically a wind turbine blade with a lightning
• protection system including a side receptor as known in the art.
• Fig. 2a is a perspective view of a side receptor according to an embodiment of the invention mounted within the surface of a wind turbine blade
• Fig. 2b is a cross-sectional view of the side receptor shown in Fig. 2a,
• Fig. 3a is a cross-sectional view of a side receptor according to an embodiment of the inv ention.
• Fig. 3b is a cross-sectional view of a side receptor according to another
• Fig. 4 is an explosive view of a side receptor according to a third embodiment of the invention mounted w ithin the surface of a wind turbine blade.
• FIG. 1 illustrates schematically a wind turbine blade 2 with a lightning protection system including a side receptor 1 as known in the art.
• the side receptor 1 is mounted within the surface of the wind turbine blade 2, preferably aligned therewith, and mechanically and electrically connected with a side receptor base 3 arranged within the wind turbine blade 2 and covered by an insulation 8.
• the side receptor 1 being typically formed as a bolt, the connection to the side receptor base 3 consists simply in a threaded connection.
• a down conductor 4 extending along the longitudinal axis of the wind turbine blade 2 ensures that the side receptor base 3 (and thereby the side receptor 1) and a tip receptor 5 of the wind turbine blade 2 are electrically connected to earth through the wind turbine nacelle and tower (not shown).
• Figs. 2a and 2b are a perspective view and a cross-sectional view, respectively, of a side receptor 1 according to an embodiment of the invention mounted within the surface of a wind turbine blade 2.
• a receptor cylinder 6 constitutes the electrically conducting part of the side receptor 1 . Its upper circular end forms the external part of the side receptor 1 being substantially aligned with the surface of the wind turbine blade 2 when the side receptor 1 is mounted therein. This i s the part being impacted by lightning strikes.
• the opposite end of the receptor cylinder 6 forms a contact surface 10 through which the lightning current passes from the side receptor 1 into the side receptor base 3 to which the side receptor 1 is connected.
• the receptor cylinder 6 is mechanically connected to the side receptor base 3 by means of a mounting bolt 9, the head of w hich is concealed within the receptor cylinder 6 and the thread part of which protrudes through a centred hole in the contact surface 10 of the receptor cylinder 6.
• the contact surface 10 is plane and perpendicular to the longitudinal axis of the receptor cylinder 6.
• the contact surface 10 or at least a part thereof can be slanted.
• Fig. 2b shows how the insulation 8 covers the side receptor base 3 as well as the side receptor 1 connected thereto. This is very important for ensuring that the lightning strikes do, in fact, pass through the side receptor 1 rather than bypassing it by penetrating the shell of the wind turbine blade 2 next to the side receptor 1 on its path to the side receptor base 3 and the down conductor inside the wind turbine blade 2.
• a washer can be arranged between the head of the mounting bolt 9 and the internal surface of the receptor cylinder 6 for securing the mounting bolt 9.
• the side receptor 2 comprises an optional blade surface protection 12 in the form of a circular sheet of a heat resistant material arranged around the receptor cylinder 6 for protecting the surface of the wind turbine blade 2 against being damaged from the excessive heat energy following lightning strikes impacting the side receptor 1 .
• thi s blade surface protection 12 is adhered to the surface of the wind turbine blade 2 during the mounting of the side receptor 1 therein.
• a sealant 13 ensures a tight connection between the side receptor 1 and the surrounding surface of the wind turbine blade 2.
• the open end of the receptor cylinder 6 is closed by a receptor plug 7, which may either be made from a solid electrically conducting or insulating material or consist of a heat-resistant paste.
• This receptor plug 7 covers and protects the head of the mounting bolt 9 from being damaged from impacting lightning strikes.
• a screw cap 14 protects the slot of the mounting bolt 9, for instance against entrance of paste, if the receptor plug 7 consists of such a paste.
• thi s embodiment of the side receptor 1 comprises a bolt insulator 15 arranged around the head of the mounting bolt 9 for ensuring electrical insulation between the mounting bolt 9 and the receptor cylinder 6 so that the lightning current is forced to pass through the contact surface 10 rather than through the threads of the mounting bolt 9 on its path from the side receptor 1 to the side receptor base 3.
• Fig. 3a is an enlarged cross-sectional view of the side receptor 1 of the two previous figures
• Fig. 3b i s a cross-sectional view of a side receptor 1 according to another embodiment of the inv ention.
• the receptor cylinder 6 is provided with a receptor ruff 1 1 extending outwards from the upper circular end of the receptor cylinder 6.
• Such a receptor ruff 1 1 is useful for ensuring a tight and weather-resistant connection between the side receptor 1 and the surrounding surface of the wind turbine blade 2 and provides additional material for the arc root erosion and, hence, the natural wear of the side receptor 1 .
• the edge of the receptor cylinder 6 is bevelled in such a way that at least a part of the contact surface 10 is slanted. This increases the area of the contact surface 10 and thereby improves the electrical connection to the side receptor base 3. Furthermore, it ensures a better mechanical stability of the connection between the side receptor 1 and the side receptor base 3.
• Fig. 4 is an explosive view of the side receptor 1 mounted within the wind turbine blade 2 as shown in Figs. 2a and 2b (but without the insulation 8 of the side receptor base).
• the receptor plug 7 may either be made from a solid material or consist of a heat-resistant paste.

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• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Sustainable Development (AREA)
• Sustainable Energy (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Wind Motors (AREA)
• Elimination Of Static Electricity (AREA)
• Emergency Protection Circuit Devices (AREA)
• Details Of Television Scanning (AREA)

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• 2015
  • 2015-04-17 WO PCT/DK2015/050100 patent/WO2016165713A1/en not_active Ceased
  • 2015-09-23 EP EP15775373.2A patent/EP3283761B1/en active Active
  • 2015-09-23 KR KR1020177033233A patent/KR20180008496A/ko not_active Withdrawn
  • 2015-09-23 JP JP2017543768A patent/JP6770668B2/ja active Active
  • 2015-09-23 CN CN201580077604.9A patent/CN107429672B/zh active Active
  • 2015-09-23 ES ES15775373T patent/ES2949174T3/es active Active
  • 2015-09-23 US US15/566,125 patent/US10288044B2/en active Active
  • 2015-09-23 WO PCT/DK2015/050290 patent/WO2016165714A1/en not_active Ceased
  • 2015-09-23 BR BR112017022337-6A patent/BR112017022337B1/pt active IP Right Grant

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