WIND TURBINE AND METHOD FOR IMPROVING THE ELECTROMAGNETIC COMPATIBILITY OF A WIND TURBINE

Abstract

Provided is a wind turbine, including a hollow tower carrying a nacelle, and at least one power electronics component emitting electromagnetic waves during operation, in particular an inverter located at the bottom of the tower, wherein the tower acts as a wave guide for an electromagnetic wave generated by the power electronics component, wherein the tower comprises at least one absorber element at least reducing the transport of the electromagnetic wave of the power electronics component along the tower.

Claims

1. A wind turbine, comprising a hollow tower carrying a nacelle, and at least one power electronics component emitting electromagnetic waves during operation, in particular an inverter located at the bottom of the tower, wherein the tower acts as a wave guide for an electromagnetic wave generated by the power electronics component, wherein the tower comprises at least one absorber element at least reducing the transport of the electromagnetic wave of the power electronics component along the tower.

2. The wind turbine according to claim 1, wherein the at least one absorber element provided in an area surrounding a position of maximum electrical field amplitude, neglecting the at least one absorber element, of the electromagnetic wave for at least one wavelength of the electromagnetic wave in the tower.

3. The wind turbine according to claim 1, wherein the multiple absorber elements are distanced by half the wavelength and/or a multiple thereof.

4. The wind turbine according to claim 1, wherein the at least one absorber element extends through the interior of the tower in a horizontal plane.

5. The wind turbine according to claim 4, wherein at least one of the at least one absorber element comprises or is a cylinder and/or at least one slab and/or has a structured surface, in particular comprising a pyramidal shape.

6. The wind turbine according to claim 4, wherein the at least one absorber element has at least one opening, in particular a through hole and/or at least one opening in the center of the tower through which at least one cable is guided.

7. The wind turbine according to claim 1, wherein the absorber element is made from at least one electrically non-conductive material and/or at least one material having a relative permittivity greater than 30.

8. The wind turbine according to claim 7, wherein the material comprises Barium titanate and/or ferrites and/or polyvinyl alcohol acetate.

9. The wind turbine according to claim 1, wherein the power electronics component is configured to perform a switching process generating the electromagnetic wave.

10. A method for improving the electromagnetic compatibility of the wind turbine according to claim 1, wherein the at least one absorber element is used to reduce the transport of the electromagnetic wave of the power electronics component along the tower.

11. The method according to claim 10, wherein the absorber element is positioned in an area surrounding a position of maximum electrical field amplitude, neglecting the at least one absorber element, of the electromagnetic wave for at least one wavelength of the electromagnetic wave in the tower.

12. The method according to claim 11, wherein the at least one position of maximum electrical field amplitude is determined by a simulation and/or analytical calculation.

Description

BRIEF DESCRIPTION

[0031] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

[0032] FIG. 1 shows a schematic general view of a wind turbine according to embodiments of the invention;

[0033] FIG. 2 shows absorber elements in the tower in a first embodiment;

[0034] FIG. 3 shows absorber elements in the tower in a second embodiment;

[0035] FIG. 4 shows absorber elements in the tower in a third embodiment;

[0036] FIG. 5 shows absorber elements in the tower in a fourth embodiment;

[0037] FIG. 6 is a cross section of the tower with an absorber element according to a fifth embodiment;

[0038] FIG. 7 shows absorber elements in the tower in a sixth embodiment;

[0039] FIG. 8 shows absorber elements in the tower in a seventh embodiment;

[0040] FIG. 9 shows absorber elements in the tower in an eighth embodiment; and

[0041] FIG. 10 shows absorber elements in the tower in a ninth embodiment.

DETAILED DESCRIPTION

[0042] FIG. 1 is a schematic drawing of a wind turbine 1 according to embodiments of the present invention, in this case an onshore wind turbine 1. The wind turbine 1 comprises a tower 2 carrying a nacelle 3, to which the hub 4 with blades 5 is attached. A generator 6 is provided in the nacelle 3 and connected to at least one further power electronics component 7 at the bottom of the tower 2, in this case an inverter 8. To connect the inverter 8 and the generator 6, cables (not shown) are guided through the hollow interior 9 of the tower 2.

[0043] In an exemplary embodiment, the inverter 8 performs a switching process with a frequency of, for example, 30 MHz, such that electromagnetic waves of this frequency are emitted into the interior 9 of the tower 2. Since the dimensions of the tower 2 provide a cut-off frequency lower than 30 MHz, the tower 2 acts as a wave guide for these electromagnetic waves which propagate in the direction of the top of the tower 2, as indicated by arrows 10. For example, if an essentially cylindrical tower having a diameter of six meters is used, the cut-off frequency is about 29.6 Mhz.

[0044] To prevent the energy of the electromagnetic wave from reaching the nacelle 3, causing emissions from the wind turbine 1, or at least reduce its strength substantially, at least one absorber element 11 extending in a horizontal plane through the interior 9 of the tower 2 is provided, made from a non-conductive, that is, dielectric material having a high relative permittivity, in an example ε.sub.r equal to 82. At least one absorber element 11 is positioned in an area where relatively high amplitudes of the electrical field are present, in particular an area surrounding a position of a local maximum of the electrical field of the electromagnetic wave. Such positions/areas may, for example, be determined by simulating the propagation of electromagnetic waves of the relevant frequency through the tower 2 without having an absorber element 11, however, since further free parameters comprise the geometry, the relative permittivity and the number of absorber elements 11, further simulations and/or calculations may of course be undertaken already in a design phase to achieve optimum absorbing properties. Due to the placement of the at least one absorber element 11, energy from the electrical field is absorbed and converted into heat.

[0045] That is, by using the at least one absorber element 11, the tower 2 is transformed from a wave guide to a wave guide filter blocking at least the frequency of the electromagnetic wave emitted by the inverter 8. In this respect, the at least one absorber element 11 may also be termed filter element.

[0046] As already mentioned, the material properties, dimensions, position and number of absorber elements 11 provide multiple free parameters that may be adapted for optimum filter properties. In the case of multiple absorber elements 11, however, these are spaced from each other at half the wavelength of the electromagnetic wave to be absorbed in the tower 2 or multiples thereof.

[0047] FIGS. 3 to 10 show concrete embodiments of absorber elements 11 and their location in the interior 9 of the tower 2.

[0048] In the first embodiment in FIG. 2, three cylindrical absorber elements 11a are provided in the interior 9 of the tower 2. It is noted that these absorber elements 11a may additionally be designed to have a stabilizing function, as is also true for stabilizer elements 11 of other embodiments.

[0049] FIG. 3 shows a second embodiment, in which two slab-like absorber elements 11b are used which extend over the whole cross-section of the tower 9.

[0050] FIG. 4 shows an embodiment in which the slab-like absorber elements 11c have a central opening 12 through which, for example, the cable may be guided along a cable guiding structure. An alternative use for these openings 12 and/or additional openings may be the transport of persons and/or objects inside the tower 2. Other embodiments may also have at least one non-central opening 12.

[0051] FIG. 5 shows a fourth embodiment, in particular a cross-section at the top 13 of the tower 2. In this case, the absorber element 11d is positioned at the top of the tower 2 and comprises a pyramidal surface.

[0052] FIG. 6 shows another cross-section through the tower 2 in a horizontal plane. In this case, a two-part absorber element 11e comprises two slab-like parts separated by an opening 14.

[0053] While these embodiments referred to an essentially cylindrical tower 2, comparable or modified embodiments may also be used for rectangular towers. Examples for such embodiments are shown in FIGS. 7 to 10.

[0054] FIG. 7 shows the use of slab-like absorber elements 11f which are shifted with respect to each other in an alternate manner. In FIG. 8, the two-part absorber elements 11g are alternatingly rotated by 90° with respect to each other. Note that, in both cases, openings 15 exist which can be used, for example, for guiding a cable or the like.

[0055] In FIG. 9, the use of cylindrically shaped absorber elements 11a as known from FIG. 2 for a rectangular tower 2 is shown. According to FIG. 10, also beam-like absorber elements 11h having a rectangular cross-section may be used.

[0056] 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.

[0057] 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.