Wind turbine rotor blade, wind turbine and method for operating a wind turbine

Abstract

A rotor blade of a wind turbine, comprising a first rotor-blade portion and a second rotor-blade portion. In this case, the first and the second rotor-blade portion constitute a total length of the rotor blade and, upon a rotation of the rotor blade, the first rotor-blade portion and the second rotor-blade portion can be moved relative to each other, along a longitudinal axis of the rotor blade, as a result of a centrifugal force acting upon the rotor blade, in such a way that the total length of the rotor blade can be altered.

Claims

1. A wind-turbine rotor blade, comprising: a first rotor-blade portion; and a second rotor-blade portion, the first and the second rotor-blade portions together forming a total length of the rotor blade, and the first and second rotor-blade portions configured so that in response to a rotation of the rotor blade, at least one of the first rotor-blade portion and the second rotor-blade portion move relative to each other as a result of a centrifugal force acting upon the rotor blade in such a way that the total length of the rotor blade is altered to an altered total length, wherein the movement is along a longitudinal axis of the rotor blade, wherein at least a portion of the second rotor-blade portion is disposed in the first rotor-blade portion, wherein the first rotor-blade portion has an opening, a portion of the second rotor-blade portion being configured to move in and out of the opening of the first rotor-blade portion, and wherein the first rotor-blade portion has a guide device for guiding and supporting the second rotor-blade portion inside the opening of the first rotor-blade portion, the guide device having at least two guide elements for guiding the second rotor-blade portion in the direction of the longitudinal axis of the rotor blade, and at least two spring elements coupling the at least two guide elements to the first rotor-blade portion.

2. The rotor blade according to claim 1, wherein the second rotor-blade portion is connected to the first rotor-blade portion by a rope winch device for retracting the second rotor-blade portion into the first rotor-blade portion.

3. The rotor blade according to claim 2, wherein the rope winch device comprises a rope for fastening to the second rotor-blade portion, the rope being made of a synthetic, polyethylene-based chemical fiber.

4. The rotor blade according to claim 2, wherein the rotor blade has a measuring means for measuring wind speed, and the rope winch device is configured so that the second rotor-blade portion retracts and extends at predefined windspeeds, respectively.

5. The rotor blade according to claim 1, wherein the guide elements are rollers.

6. The rotor blade according to claim 1, wherein the guide device is box shaped and is disposed inside the first rotor-blade portion.

7. The rotor blade according to claim 1, wherein the guide device has a length that is one third of a length of the second rotor-blade portion that moves out of the first rotor-blade portion.

8. The rotor blade according to claim 1, wherein a length of the portion of the second rotor-blade portion that moves out of the opening of the first rotor-blade portion corresponds approximately to one tenth of the total length of the rotor blade.

9. The rotor blade according to claim 1, wherein the first rotor-blade portion has a first rotor-blade tip, and the second rotor-blade portion has a second rotor-blade tip, the first rotor-blade tip and the second rotor-blade tip each being realized as winglets, and the second rotor-blade tip being provided in an opposite direction to the first rotor-blade tip.

10. The rotor blade according to claim 9, wherein the second rotor-blade portion has a stop at an end opposite to the second rotor-blade tip in a longitudinal direction, wherein the stop ensures a predefined extendable length.

11. The rotor blade according to claim 1, wherein the second rotor-blade portion has a substantially constant profile depth over its entire length.

12. The rotor blade according to claim 9, wherein at least one of the first and second rotor-blade portions is produced substantially from a fibrous composite material or wood, and at least one of the first and second rotor-blade tips is produced from a conductive material.

13. The rotor blade according to claim 1, wherein at least one of the first and the second rotor-blade portions is connected to a lightning protection means by a metal rail or a metal cable.

14. A wind turbine comprising: a nacelle; a rotor; and at least one rotor blade according to claim 1 coupled to the rotor.

15. The wind turbine according to claim 14, wherein a diameter of the rotor is enlarged in response to a rotation of the rotor blade.

16. A method for operating a wind turbine having at least one wind-turbine rotor blade according to claim 1, the method comprising: rotating the at least one wind-turbine rotor blade, wherein rotating the at least one wind-turbine rotor blade causes the second rotor-blade portion to move relative to the first rotor-blade portion as a result of an occurring centrifugal force.

17. The method according to claim 16, wherein the second rotor-blade portion is moved out of the first rotor-blade portion as a result of the centrifugal force occurring such that a surface area of the at least one wind-turbine rotor blade acted upon by the wind is enlarged.

18. The method according to claim 16, further comprising moving the second rotor-blade portion back into the first rotor-blade portion using a rope winch device such that a first surface area of the rotor blade acted upon by wind is reduced in comparison with a second surface area acted upon by the wind in the case of a fully extended second rotor-blade portion.

19. The method according to claim 16, wherein the method occurs in light wind.

20. The rotor blade according to claim 1, wherein the guide device has four guide elements and four spring elements.

21. The rotor blade according to claim 20, wherein guide device includes a box, wherein the four guide elements are four rollers, wherein the four rollers and the four spring elements are distributed over an entire length of the box.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) The invention is explained exemplarily in the following on the basis of exemplary embodiments, with reference to the accompanying figures. The figures in this case contain partially simplified, schematic representations.

(2) FIG. 1 shows a wind turbine, in a perspective view.

(3) FIG. 2 shows a rotor blade, in a side view.

(4) FIG. 3 shows the rotor blade of FIG. 2, in a further side view.

(5) FIG. 4 shows a detail of the rotor blade from FIG. 3 in an extended state, in a side view.

(6) FIG. 5 shows a detail of the rotor blade of FIG. 2 in an extended state, in a further side view.

(7) FIG. 6 shows a sectional view of the rotor blade from FIG. 5.

DETAILED DESCRIPTION

(8) FIG. 1 shows a wind turbine 100 having a tower 102 and a nacelle 104. Disposed on the nacelle 104 is a rotor 106, having three rotor blades 200 and a spinner 110. When in operation, the rotor 106 is put into a rotary motion by the wind, and thereby drives a generator in the nacelle 104.

(9) FIG. 2 shows a side view of a rotor blade 200 of one embodiment, over its entire length L. The rotor blade 200 has a first rotor-blade portion 201, and has a second rotor-blade portion (not represented). In addition, the rotor blade 200 has a rotor-blade root 203 at one end, and at the end that faces away from the latter has a rotor-blade tip 204. The figure also shows a longitudinal axis 214 of the rotor blade 200.

(10) FIG. 3 shows a further side view of the rotor blade 200 of FIG. 2. The second rotor-blade portion has not been moved out of the first rotor-blade portion 201. The rotor blade 200 thus has its minimum total length L. The figure shows the rotor blade 200 with the first rotor-blade portion 201, having the first rotor-blade tip 204, as well as the second rotor-blade tip 205 of the second rotor-blade portion. The first rotor-blade tip 204 and the second rotor-blade tip 205 in this case are realized as a so-called winglet. They thus do not continue straight in the direction of the longitudinal axis 214 to the tip of the rotor blade, but are provided in a direction that deviates from the longitudinal axis 214 of the rotor blade 200. This lessens the edge eddy at the end of the rotor blade, and the noise of the wind turbine is reduced. The first rotor-blade tip 204 and the second rotor-blade tip 205 point in differing directions. This results in a so-called T-tip rotor blade.

(11) FIG. 4 shows an enlarged detail of the rotor blade 200 from FIG. 3. It can be seen that the second rotor-blade portion 202 is disposed inside the first rotor-blade portion 201. The second rotor-blade portion 202 has been moved out of the first rotor-blade portion. Moreover, the profile depth 213 of the second rotor-blade portion 202 is designed so as to be substantially constant. It is thus ensured that the second rotor-blade portion 202 can be reliably retracted into and extended out of the first rotor-blade portion 201.

(12) FIG. 5 shows an enlarged detail of the rotor blade 200 from FIG. 2, the second rotor-blade portion 202 projecting out of the first rotor-blade portion 201. The second rotor-blade portion 202 has a constant profile depth, at least as far as the second rotor-blade tip 205, i.e., a constant size between the nose and the trailing edge, or a constant contour. It is thereby ensured that the second rotor-blade portion 202 can slide without difficulty out of or into an opening 201a correspondingly provided in the first rotor-blade portion 201.

(13) The first rotor-blade portion 201 has a rope winch device 209 and, connected thereto, a rope 208 that is connected to the rope winch device 209 and to the second rotor-blade portion 202. The rope 208 in this case is realized, for example, as a rope made of a synthetic polyethylene-based chemical fibre. The second rotor-blade portion 202 has a stop 207, which strikes on the box 206 in the case of a maximally extended length. The stop 207 prevents the second rotor-blade portion 202 from projecting too far out of the first rotor-blade portion 201. In FIG. 5, the maximum length by which the second rotor-blade portion 202 can project out of the first rotor-blade portion 201 is equal to one tenth of the total length L of the rotor blade 200. The box 206 in this case has a length 215 of one third of the projecting length of the second rotor-blade portion 202.

(14) FIG. 6 shows a sectional view B-B of the rotor blade 200 of FIG. 5. It can be seen from FIG. 6 that the second rotor-blade portion 202 is provided inside the box 206 disposed in the first rotor-blade portion 201. The box 206 is part of a guide device 210, by which the second rotor-blade portion 202 is guided out of and back into the first rotor-blade portion 201. The guide device 210 in this case comprises a plurality of rollers 211, and a plurality of spring elements 212, four of each being represented in FIG. 6. Preferably in this case, such rollers 211 and spring elements 212 are distributed over the entire length of the box 206. Owing to the spring elements 212, the rollers 211 are able to adapt to the contour of the second rotor-blade portion 202. The springs 212 have a predefined spring stiffness, which ensures that the second rotor-blade portion 202 is held in a predefined position and, as a result, movement in a longitudinal direction becomes possible.

(15) The box 206 in this case is likewise part of the structure of the first rotor-blade portion 201. The box 206 in this case is composed of two transverse walls 217 that are substantially parallel to each other, and of two side walls 216 that are arranged substantially with respect to each other. Provided on each of the transverse walls 217 are two springs 212 and two rollers 211, which guide the second rotor-blade portion 201 and support it inside the first rotor-blade portion 201.