Owing to their large overall height, wind turbines are affected particularly frequently by a lightning strike. Most frequently, the lightning strikes in the region of the tip of a rotor blade pointing straight up. In order to prevent damage to or even destruction of the rotor blade by the lightning strike, it is known to arrange a lightning receptor in the region of the rotor blade tip and to connect it to a lightning conductor. The current from a lightning flash striking the lightning receptor is then discharged via the lightning conductor to the rotor blade root, from there into the hub, via the nacelle and the tower of the wind turbine to ground.
In practice, however, damage occurs again and again to the rotor blades through lightning strikes. For example, electromagnetic induction can result in arcing occurring between different, electrically conductive structures of a rotor blade. It has also been observed that a lightning flash does not strike directly into a lightning receptor provided therefor but at the edge of the lightning receptor or at a distance therefrom and from there finds another way to the lightning conductor or some other conductive structure. Here, for example, fiber-reinforced plastic materials of the rotor blade can be affected, leading to irreparable damage to the rotor blade.
Document WO 2013/007267 A1 discloses a wind turbine rotor blade having a metallic lightning receptor on the blade tip. In addition, copper meshes or foils are to be mounted on a surface of the rotor blade.
Document DE 10 2005 051 537 A1 discloses a method for retrofitting a lightning protection system in a rotor blade. For this purpose, a rotor blade tip is to be cut off and replaced by a metallic lightning receptor. In some embodiments, the lightning receptor has extensions on the profile nose edge or on the profile end edge that are to be connected to lightning conductors arranged on the outside of the wind turbine rotor blade.
Document EP 2 712 472 B2 discloses a wind turbine rotor blade having a lightning protection device. The latter has a multi-part lightning receptor which is combined with metal foils or meshes.
Document EP 1 668 246 B1 discloses a lightning receptor of multi-part configuration for a wind turbine rotor blade. The lightning receptor is mounted with the aid of a plurality of rods made of a plastic material.
Document WO 2010/100283 A1 discloses a wind turbine rotor blade having a blade tip formed by a plastic part into which a lightning receptor and a lightning conductor are incorporated. Additional electrically conductive layers are arranged on the outside of the rotor blade and isolated from the lightning conductor.
Document EP 2 267 280 A2 discloses arranging a flat layer of a conductive or semi-conducting material on the tip of a wind turbine rotor blade, which material is to exert a field-homogenizing effect in the event of a lightning strike.
Document EP 2 532 893 A1 discloses a lightning receptor for a wind turbine rotor blade, which lightning receptor is made of metal and forms a blade tip of the rotor blade. The lightning receptor has a fastening portion which faces away from the blade tip and which is fastened in the rotor blade. A ceramic component is inserted between the rotor blade and the lightning receptor and surrounds a part of the fastening portion and, owing to its heat resistance, is to avoid damage to the rotor blade when lightning strikes the lightning receptor.
Document DE 10 2015 200 370 A1 discloses a wind turbine rotor blade the tip of which is formed from a metallic lightning receptor. In one embodiment, the lightning receptor has an extension extending along a profile end edge of the rotor blade.
USPTO Backgrounds
USPTO Backgrounds