DESIGN OF A WIND TURBINE

Abstract

A method for designing a wind energy plant with a generator and with a rotor with rotor blades, comprising the steps determining the size of the wind energy plant which is to be designed, more particularly the rotor diameter and axle height, for a proposed installation site, designing the wind energy plant for a reduced maximum load which is lower than a maximum load which occurs when a 50-year gust strikes the wind energy plant from a maximum loading side.

Claims

1. A method comprising: designing a wind energy plant with a generator and a rotor with rotor blades, wherein designing comprises: determining the size a rotor diameter and an axle height of the wind energy plant for a proposed installation site, and determining a maximum load based on a 50-year gust strike for the proposed installation site when the wind strikes the wind energy plant from a side or a backside, wherein the rotor diameter and the axle height are of sizes to withstand only up to a reduced maximum load that is less than the maximum load; and installing the wind energy plant at the proposed installation site.

2. The method according to claim 1 wherein the reduced maximum load is a load which occurs when the 50-year gust strikes the wind energy plant from a direction which leads to a minimal load on the wind energy plant.

3. The method according to claim 1 wherein the reduced maximum load is a load which occurs when the 50-year gust strikes the wind energy plant from a front side of the wind energy plant and when the rotor blades are displaceable rotor blades and the rotor blades are in the feathered position.

4. The method according to claim 1 wherein the reduced maximum load is a load which occurs when the 50-year gust strikes the wind energy plant substantially from a front side of the wind energy plant that includes a region of +/−20° from a rotational axis of the rotor.

5. The method according to claim 1 further comprising determining a dimension of a nacelle, a dimension of a tower, a dimension of a tower foundation, and dimensions for rotor blades for the proposed installation site, wherein dimension of the nacelle, the dimension of the tower, the dimension of the tower foundation, and dimensions for rotor blades are sized to withstand only up to a reduced maximum load that is less than the maximum load.

6. A method comprising: operating a wind energy plant; detecting a wind above a threshold value; and aligning the wind energy plant so that its azimuth position faces into the wind to thereby provide to a reduced maximum load applied to the wind energy plant by the wind than when a side of the wind energy plant faces into the wind.

7. The method according to claim 6 further comprising repeatedly aligning the azimuth position of the wind energy plant into the wind as a direction of the wind changes over time.

8. The method according to claim 7 wherein repeatedly aligning the azimuth position comprises using power required from an energy accumulator when there is no or no sufficient power to be drawn from at least one of the electric supply network and the generator.

9. The method according to claim 6 wherein aligning the wind energy plant comprises rotating a nacelle of the wind energy plant so that a spinner of the nacelle substantially faces into a prevailing direction of the wind.

10. Method according to claim 6 further comprising stopping the wind energy plant from operating.

11. The method according to claim 6 further comprising detecting a wind direction, wherein aligning the wind energy plant so that its azimuth position faces into the wind is based on the detected wind direction.

12. The method according to claim 6 further comprising: rotating the rotor so that a rotor blade coupled to the rotor is in a 6 o'clock position; and allowing the rotor to freely rotate about its rotor rotational axis.

13. A wind energy plant located in a wind farm that has a 50-year wind gust, the energy plant comprising: a tower; a nacelle; a generator in the nacelle; and a rotor rotatably coupled to the nacelle, a plurality of rotor blades coupled to the rotor, wherein a rotor diameter and an axle height of the wind energy plant are sized to withstand the 50-year wind gust when a front face of the rotor is substantially facing into the wind and is not sized to withstand the 50-year wind gust when a side of the rotor is facing into the wind.

14. The wind energy plant according to claim 13 comprising at least one measuring apparatus for detecting a wind direction and is configured to be operated by an electric energy accumulator.

15. A wind farm comprising at least two wind energy plants according to claim 13.

16. The wind energy plant according to claim 13 wherein at least two measuring apparatuses are each provided on the wind energy plant for detecting a wind direction.

17. The method according to claim 9 wherein the spinner of the nacelle substantially faces into the prevailing direction of the wind when the prevailing direction of the wind is in a region of +/−20° from a rotational axis of the rotor.

18. The method according to claim 11 wherein the wind energy plant is a first wind energy plant, wherein detecting the wind direction is performed at a second wind energy plant, wherein the first and second wind energy plants are located in a wind farm.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0043] The invention will now be explained in further detail with reference to embodiments by way of example with reference to the accompanying figures in which

[0044] FIG. 1 shows a wind energy plant diagrammatically in a perspective view;

[0045] FIG. 2 shows a wind farm in a diagrammatic illustration;

[0046] FIG. 3 shows a plan view of a wind energy plant nacelle in a diagrammatic and simplified illustration to indicate the direction of a possible wind attack;

[0047] FIG. 4 shows on a diagrammatic load curve B possible load fluctuations in dependence on the attack direction of the wind.

DETAILED DESCRIPTION

[0048] FIG. 1 shows a wind energy plant 100 with a tower 102 and a nacelle 104. A rotor 106 is arranged with three rotor blades 108 and a spinner 110 on the nacelle 104. The rotor 106 is set in operation in rotational movement by the wind and thereby drives a generator in the nacelle 104.

[0049] FIG. 2 shows a wind farm 112 with by way of example three wind energy plants 100 which can be the same or different. The three wind energy plants 100 are thus representative of the basically any number of wind energy plants of a wind farm 112. The wind energy plants 100 supply their power, namely in particular the generated current, via an electric farm network 114. The currents or power capacities each produced by the individual wind energy plants 100 are thereby added up and mostly a transformer 116 is provided which transforms the voltage in the farm, in order then to feed it into the supply network 120 at the feed-in point 118 which is also generally termed a PCC. FIG. 2 shows only a simplified illustration of a wind farm 112 which shows by way of example no control system, although naturally a control system is present. Also by way of example the farm network 114 can be configured differently in which by way of example a transformer is also provided at the output of each wind energy plant 100, in order only to quote another exemplary embodiment.

[0050] FIG. 3 shows of a wind energy plant in a diagrammatic plan view a nacelle 2 and a rotor blade 4 indicated in its prepared outline as well as an outline of a tower 6 shown in dotted lines in its upper region. As shown in FIGS. 1 and 2 it basically starts from a wind energy plant with three rotor blades. Thus in FIG. 3 in addition to the rotor blade 4, which here is shown in a 12 o'clock position, two further rotor blades would be seen, namely in the 4 o'clock position and 8 o'clock position. For simplification these two rotor blades are however omitted. The illustrated rotor blade is thus arranged together with the illustrated spinner 10 rotatable about the horizontal rotor rotational axis 8.

[0051] Furthermore the rotor blade 4 is adjustable about the pitch axis 12, shown only as a point, in its set-up angle to the wind. FIG. 3 shows thus far a feathered position of the rotor blade 4. It is thereby to be noted that FIG. 3 is a diagrammatic illustration which for simplification of the illustration does not go into the usual torsion of the rotor blade. The illustrated section of the rotor blade 4 is thus to illustrate the feathered position representative for the entire rotor blade 4.

[0052] The illustrated nacelle 2 is furthermore displaceable about a vertical azimuth axis 14 so that the nacelle can be aligned in a desired position relative to the wind.

[0053] FIG. 3 shows symbolically four possible wind directions W which are drawn in here for four directions, namely 0°, 90°, 180° and 270°. Naturally all the intermediate directions are also possible. These wind directions W relate in this illustration to the aligned nacelle 2 and thus to the alignment of the rotor rotational axis 8. This relative alignment of the wind direction W in relation to the nacelle also forms the basis of the illustration of FIG. 4 which will be explained below.

[0054] FIG. 3 now shows a preferred alignment of the wind energy plant with its nacelle 2 for the case where the wind direction amounts to 0° as drawn. This preferred embodiment also has the rotor blades 4 in the feathered position, as is indicated for the example of the rotor blade 4.

[0055] The three further wind directions which have been drawn in, namely 90°, 180° and 270°, represent the wind directions or alignments of the nacelle 2, which are thus not desired.

[0056] Particularly for the wind direction W at 90° a large attack surface is produced for the nacelle 2 on account of the lateral flow. Furthermore the wind here flows onto the pressure side 16 of the rotor blade 4. It should in any case be noted that FIG. 3 is only for illustration and it is particularly preferred if the wind energy plant is provided with one rotor blade in the 6 o'clock position and the other two rotor blades are in the 10 o'clock and 2 o'clock position respectively.

[0057] It hereby arises that the opposite passing flow, namely at 270°, also as a whole means the load for the wind energy plant is not much smaller.

[0058] FIG. 3 thus also shows the wind direction W at 180°, thus for wind which attacks the nacelle from behind. Such load ought indeed be lower than a load from side wind, because the attack face on the nacelle is also lower than in the case of a side wind, but the wind energy plant is basically designed for wind from the front, thus wind at 0° or 360° according to FIG. 3. By way of example the illustrated feathered position of the rotor blade 4 is also more favorable for wind with wind direction W of 0° or 360° respectively, than for a wind direction W of 180°.

[0059] FIG. 4 shows a load curve B which is to depict a possible load curve in dependence on the wind direction W. The wind direction W which is entered with corresponding degrees on the abscissa is used for understanding FIG. 3. 0° and 360° respectively is thus a wind direction from the front on the nacelle 2 or the spinner 10.

[0060] FIG. 4 now shows, where the curve represents a simplified path, that a minimum load B.sub.min, exists at 0° and 360° respectively. A maximum load is assumed at 90° and a similarly high, only slightly less load is assumed at 270°. At 180° the load is lower, but in any case greater than the minimum load at 0°.

[0061] The illustrative curve of FIG. 4 thereby has standardized the load at a load value of B.sub.min. The maximum load B.sub.max is thus set at one.

[0062] It is now proposed to design the wind energy plant not for the load B.sub.max, but for the reduced load of B.sub.min.

[0063] There are many possibilities for including such a load on the wind energy plant. One possibility consists in using the forces which occur at a load-critical point. Such forces can be taken up and integrated from several critical points, thus by way of example a blade root, a tower head, a tower foot and an axle pivot fastening. The illustration of FIG. 4 is the basis of one such consideration.

[0064] In the case of the actual design it would then naturally be ensured that each individual critical point is not loaded beyond its load limit even in the event of a 50-year gust. For selecting the underlying marginal conditions where the reduced maximum load occurs it is expedient to consider one such integrating illustration according to FIG. 4. Finally these marginal conditions, thus in particular the alignment of the nacelle, the rotor and the rotor blades, must then be the basis for each of the critical components or investigated points.