This application claims priority to EP Application No. 19164670.2, having a filing date of Mar. 22, 2019, the entire contents of which are hereby incorporated by reference.
The following relates to a nacelle of a wind turbine having a cover for providing an efficient lightning protection.
In a wind turbine a lightning protection arrangement has to be provided for guiding a lightning stroke from the impact point down to ground. Blades are the most typical wind turbines component, which are subject to being hit by a lightning stroke. Typically, a lightning protection arrangement has therefore to guide a lightning stroke from the blades, through the hub structure and the wind turbine main shaft to the nacelle cover and the tower down to earth. The current flowing from the impact #point to the ground tends naturally to move towards the external cover of the nacelle, according to the known skin effect.
An aspect relates to that of providing, in a nacelle for a wind turbine, an optimized current path for a lightning stroke towards the ground by optimizing the conductivity of the nacelle cover.
According to embodiments of the invention there is provided a wind turbine including:
a hub,
at least one blade fixed to the hub,
a nacelle on which the hub is rotatably mounted for rotating about a rotational axis,
a tower on which the nacelle is mounted,
a plurality of hitting areas which are subject to be hit by a lightning stroke, wherein the nacelle comprises an outer cover having a first plurality of portions comprising a conductive material and a second plurality of portions comprising a non-conductive material, the first plurality of portions being arranged along at least a path between the plurality of hitting areas and the tower.
Hitting areas may be located on the blades or on a rear section of the nacelle opposite to the hub.
Once an optimal current path for a lightning stroke is defined from the expected hitting areas and the ground, the first plurality of portions comprising a conductive material and the second plurality of portions comprising a non-conductive material can be arranged relatively to each other to guide the lightning stroke along said path.
With respect to nacelle covers completely made of a conductive material or completely made of a non-conductive material the nacelle cover of embodiments of the present invention provides a plurality of advantages, among which:
enhancing the natural behavior of a lightning path towards the external surface of the nacelle (skin effect),
improving the level of lightning protection according to the standard IEC 61400-24, which can reduce the requirements to electrical parts inside the nacelle with consequent cost savings,
increasing the protection level of operators eventually present inside the nacelle,
decreasing the electromagnetic compatibility emissions to the surroundings,
reducing the amount of expensive and heavy conductive portions, in particular made of steel, thereby also reducing costs and weight of the nacelle,
reducing the maintenance time required to perform service on parts in the improved lightning path.
In embodiments of the present invention, a portion of the outer cover comprising a conductive material may be provided in a front section of the nacelle adjacent to the hub. Such portion may provide a good electrical connection with the tower of the wind turbine for guiding a lightning strike down to the ground. Alternatively, or additionally, a portion of the outer cover comprising a conductive material may be provided in a rear section of the nacelle opposite to the hub. Advantageously this arrangement provides an optimized path for a lightning strike hitting the rear section of the nacelle. A portion of the outer cover comprising a conductive material may be provided in a middle section of the nacelle for connecting the front section and the rear section of the nacelle. This arrangement may provide an optimized path for a lightning strike hitting the rear section of the nacelle towards the front section and the tower.
In embodiments of the present invention, the first plurality of portions may comprise steel or other conductive metal. The second plurality of portions may comprise glass fiber or an aluminum non-conductive alloy or other non-conductive metal. Material may be in particular chosen, which also an effective protection in case of fire.
The aspects defined above and further aspects of embodiments of the present invention are apparent from the examples of embodiment to be described hereinafter and are explained with reference to such examples of embodiment. Embodiments of the invention will be described in more detail hereinafter with reference to examples of embodiment but to which embodiments of the invention are not limited.
Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:
The drawings are in schematic form. Similar or identical elements are referenced by the same or different reference signs.
The wind turbine 10 comprises a hub 13 which is rotatably attached to the nacelle 12 for rotating about a rotor axis Y, which is a longitudinal axis Y of the nacelle 12. When not differently specified, the terms axial, radial and circumferential in the following are made with reference to the longitudinal rotor axis Y. The hub 13 is often described as being a part of a wind turbine rotor, wherein the wind turbine rotor is capable to rotate about the rotor axis Y and to transfer the rotational energy to an electrical generator (not shown).
The wind turbine 1 further comprises at least one blade 17 (in the embodiment of
The wind turbine 1 comprises a plurality of hitting areas 20 a lightning strike may be subject to hit the wind turbine. The plurality of hitting areas 20 includes the external surfaces of the blades 17 of the wind turbine 10, in particular the radial ends (tips) of the blades 17. Other hitting areas are located a rear section of the nacelle opposite to the hub. Other hitting areas may be foreseen depending on the type and on the dimensions of the wind turbine.
With reference to the embodiment shown in
Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.
For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.
Number | Date | Country | Kind |
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19164670 | Mar 2019 | EP | regional |
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Entry |
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European Search Report dated Sep. 27, 2019 for Application No. 19164670.2. |
Number | Date | Country | |
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20200300229 A1 | Sep 2020 | US |