Wind turbine

Abstract

A wind turbine is provided, including a container, a fluid which is arranged inside the container, and a damping body which is arranged inside the container, which is immersed in the fluid, and which is configured to move inside the container, wherein the fluid and the damping body are configured to damp oscillations of the wind turbine. A damper system is provided that on the one hand the fluid damps, e.g. by sloshing, and on the other hand the damping body damps by moving at least partially through the fluid.

Claims

1. A wind turbine comprising at least one container; a fluid arranged inside the container; and a damping body arranged inside the container, which is immersed in the fluid, and configured to move inside the container, wherein the fluid and the damping body are configured to damp oscillations of the wind turbine; wherein the container and the damping body are configured such that a full rotation of the damping body inside the container is prevented; wherein a moving path of the damping body within the container extends from a first end face to a second end face opposite the first end face; wherein the container comprises a sliding surface for the damping body, the sliding surface having a curved shape.

2. The wind turbine according to claim 1, further comprising a tower, wherein the container is arranged inside the tower.

3. The wind turbine according to claim 1, wherein a cross-section of the damping body fills at least 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95% or 98% of a cross-section of the container.

4. The wind turbine according to claim 1, wherein a sliding surface of the damping body has a curved shape.

5. The wind turbine according to claim 1, wherein the damping body has a square, pentagonal, rectangular or trapezoidal cross-sectional shape.

6. The wind turbine according to claim 1, wherein one of the damping body and the container comprises a recess and the other of the damping body and the container comprises a guiding element which interacts with the recess for guiding the damping body along a length of the container.

7. The wind turbine according to claim 1, wherein the container comprises an end portion and the damping body comprises an end portion for fitting into the end portion of the container, wherein the container and the damping body are configured such that fluid is dammed between an end face of the damping body and an end face of the container when the end portion of the damping body fits into the end portion of the container.

8. The wind turbine according to claim 1, wherein an inner space of the container comprises a height that is constant along a length of the container or which decreases along the length of the container.

9. The wind turbine according to claim 8, wherein at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or 90% of the inner space of the container is filled with the fluid.

10. The wind turbine according to claim 1, further comprising a first container and a first damping body which is arranged with the fluid inside the first container, and a second container and a second damping body which is arranged with the fluid inside the second container.

11. The wind turbine according to claim 10, wherein the first container crosses the second container.

12. The wind turbine according to claim 10, wherein the first container is arranged parallel to the second container.

13. The wind turbine according to claim 12, further comprising a cable which is arranged between the first container and the second container.

14. A wind turbine comprising at least one container; a fluid arranged inside the container; and a damping body arranged inside the container, which is immersed in the fluid, and configured to move inside the container, wherein the fluid and the damping body are configured to damp oscillations of the wind turbine; wherein the container and the damping body are configured such that a full rotation of the damping body inside the container is prevented; wherein a moving path of the damping body within the container extends from a first end face to a second end face opposite the first end face; wherein one of the damping body and the container comprises a recess and the other of the damping body and the container comprises a guiding element which interacts with the recess for guiding the damping body along a length of the container.

15. A wind turbine comprising a first container; a fluid arranged inside the first container; a first damping body arranged inside the first container, which is immersed in the fluid, and configured to move inside the first container, wherein the fluid and the first damping body are configured to damp oscillations of the wind turbine; a second container arranged parallel to the first container; and a second damping body arranged inside the second container, which is immersed in a fluid within the second container, and configured to move inside the second container, wherein the fluid and the second damping body are configured to damp oscillations of the wind turbine; wherein the first container and the first damping body are configured such that a full rotation of the first damping body inside the first container is prevented; wherein a moving path of the first damping body within the container extends from a first end face to a second end face opposite the first end face.

Description

BRIEF DESCRIPTION

(1) Some of the embodiments will be described in detail, with references to the following Figures, wherein like designations denote like members, wherein:

(2) FIG. 1 shows a perspective view of a wind turbine according to one embodiment;

(3) FIG. 2 shows a cross-section II-II from FIG. 1 of one embodiment of a tower;

(4) FIG. 3 shows the cross-section II-II from FIG. 1 of a further embodiment of a tower;

(5) FIG. 4 shows the cross-section II-II from FIG. 1 of a further embodiment of a tower;

(6) FIG. 5 shows the cross-section II-II from FIG. 1 of a further embodiment of a tower;

(7) FIG. 6 shows a schematic perspective view of a plurality of containers;

(8) FIG. 7 shows a cross-section VII-VII from FIG. 4 of one embodiment of a container;

(9) FIG. 8 shows a cross-section VII-VII from FIG. 4 of a further embodiment of the container;

(10) FIG. 9 shows a cross-section VII-VII from FIG. 4 of a further embodiment of the container;

(11) FIG. 10 shows a cross-section VII-VII from FIG. 4 of a further embodiment of the container;

(12) FIG. 11 shows a cross-section VII-VII from FIG. 4 of a further embodiment of the container;

(13) FIG. 12 shows a cross-section VII-VII from FIG. 4 of a further embodiment of the container;

(14) FIG. 13 shows a cross-section VII-VII from FIG. 4 of a further embodiment of the container;

(15) FIG. 14 shows detail view XIV from FIG. 13 of a further embodiment of the container;

(16) FIG. 15 shows a cross-section VII-VII from FIG. 4 of a further embodiment of the container;

(17) FIG. 16 shows a cross-section XVI-XVI from FIG. 7 of a first embodiment of the container;

(18) FIG. 17 shows a cross-section XVI-XVI from FIG. 7 of a second embodiment of the container;

(19) FIG. 18 shows a cross-section XVI-XVI from FIG. 7 of a third embodiment of the container;

(20) FIG. 19 shows a cross-section XVI-XVI from FIG. 7 of a fourth embodiment of the container;

(21) FIG. 20 shows a cross-section XVI-XVI from FIG. 7 of a fifth embodiment of the container;

(22) FIG. 21 shows a cross-section XVI-XVI from FIG. 7 of a sixth embodiment of the container;

(23) FIG. 22 shows a cross-section XVI-XVI from FIG. 7 of a seventh embodiment of the container;

(24) FIG. 23 shows a cross-section XVI-XVI from FIG. 7 of an eighth embodiment of the container;

(25) FIG. 24 shows a cross-section XVI-XVI from FIG. 7 of a ninth embodiment of the container;

(26) FIG. 25 shows a cross-section XVI-XVI from FIG. 7 of a tenth embodiment of the container;

(27) FIG. 26 shows a cross-section XVI-XVI from FIG. 7 of an eleventh embodiment of the container;

(28) FIG. 27 shows a cross-section XVI-XVI from FIG. 7 of a twelfth embodiment of the container;

(29) FIG. 28 shows a cross-section XVI-XVI from FIG. 7 of a thirteenth embodiment of the container;

(30) FIG. 29 shows a cross-section XVI-XVI from FIG. 7 of a fourteenth embodiment of the container;

(31) FIG. 30 shows a cross-section XVI-XVI from FIG. 7 of a fifteenth embodiment of the container;

(32) FIG. 31 shows a cross-section XVI-XVI from FIG. 7 of a sixteenth embodiment of the container;

(33) FIG. 32 shows a cross-section XVI-XVI from FIG. 7 of a seventeenth embodiment of the container;

(34) FIG. 33 shows a cross-section VII-VII from FIG. 4 of a further embodiment of the container;

(35) FIG. 34 shows a cross-section VII-VII from FIG. 4 of a further embodiment of the container;

(36) FIG. 35 shows a cross-section VII-VII from FIG. 4 of a further embodiment of the container; and

(37) FIG. 36 shows a cross-section VII-VII from FIG. 4 of a further embodiment of the container.

DETAILED DESCRIPTION

(38) FIG. 1 shows a wind turbine 1. The wind turbine 1 comprises a rotor 2 connected to a generator (not shown) arranged inside a nacelle 3. The nacelle 3 is arranged at the upper end of a tower 4 of the wind turbine 1.

(39) The rotor 2 comprises three wind turbine blades 5. The wind turbine blades 5 are connected to a hub 6 of the wind turbine 1. Rotors 2 of this kind may have diameters ranging from, for example, 30 to 200 meters or even more. The wind turbine blades 5 are subjected to high wind loads. At the same time, the wind turbine blades 5 need to be lightweight. For these reasons, wind turbine blades 5 in modern wind turbines 1 are manufactured from fiber-reinforced composite materials. Therein, glass fibers are generally preferred over carbon fibers for cost reasons. Oftentimes, glass fibers in the form of unidirectional fiber mats are used.

(40) The tower 4 comprises a lower end 7 and an upper end 8, wherein the lower end 7 is averted from the nacelle 3. Further, the nacelle 3 is connected to the upper end 8 of the tower 4. When the wind turbine 1 e.g. is subjected to high wind loads, the upper end 8 together with the nacelle 3 moves away from a neutral position which results in oscillations. Usually, an amplitude of such an oscillation is larger at the upper end 8 than at the lower end 7. Thus, it may be useful to provide damper systems at the upper end 8 of the tower 4 or the nacelle 3.

(41) FIG. 2 shows schematically a cross-section II-II of an embodiment of the tower 4 from FIG. 1 which intersects the upper end 8 (see FIG. 1) of the tower 4. In particular, FIG. 2 shows a top view to the inside of the tower 4. The tower 4 comprises a wall 9 which is an outermost wall of the tower 4 and, thus, faces an outer environment 10 of the wind turbine 1. The wall 9 has a circular ring-shaped cross-section and surrounds an inner space 11 of the tower 4. Further, a container 12 is provided inside the inner space 11.

(42) The container 12 has essentially a rectangular shape when looking from above and is, in particular rigidly, connected to the tower 4 (not shown). Further, the container 12 comprises a first end face 13 (or end wall) and a second end face 14 (or end wall) both facing the wall 9 and averted from each other. A length L of the container 12 may be at least 50%, 60%, 70%, 80%, 90%, 95% or 98% of an inner diameter D of the wall 9. A fluid 29 (not shown) and a damping body 30 (also indicated as first damping body) are arranged inside the container 12 (see broken lines). The damping body 30 is immersed in the fluid 29 (see FIG. 7), and is configured to move inside the container 12, wherein the fluid 29 and the damping body 30 are configured to damp oscillations of the wind turbine 1. The container 12, the fluid 29 and the damping body 30 may be named damper system.

(43) Further, a damping direction R1 extends from the end face 14 towards the end face 13 and vice versa. The container 12 is elongated towards the damping direction R1. The inner space 11 is essentially cylindrical and has a rotational symmetry regarding a middle axis 15, wherein the container 12 intersects the middle axis 15 of the inner space 11.

(44) In particular, a further container 16 (also indicated as second container) is provided. The fluid 29 (not shown) and a damping body 30′ (also indicated as second damping body) are arranged inside the container 16 (see broken lines). The damping body 30′ is immersed in the fluid 29, and is configured to move inside the container 16, wherein the fluid 29 and the damping body 30′ are configured to damp oscillations of the wind turbine 1. The container 12 and the container 16 may be identical, wherein a damping direction R2 of the container 16 is essentially perpendicular to the damping direction R1. Thus, the tower 4 may be damped in two directions R1, R2 perpendicular to each other. In particular, the containers 12, 16 are placed above one another optionally with a distance in between in vertical direction Z which also is a longitudinal direction of the tower 4 (see FIG. 1) but turned 90° relative to one another. The containers 12, 16 are placed as close to the nacelle 3 (see FIG. 1), i.e. at topmost possible point in the upper end 8 of the tower 4. Alternatively, the containers 12, 16 may be placed within the nacelle 3. The containers 12, 16 may be provided as pair of containers 12, 16.

(45) FIG. 3 shows schematically the cross-section II-II from FIG. 1 of a further embodiment of the tower 4. Two pairs of containers 12, 16, 17, 18 may be placed of one another at the upper end 8, in particular on top, of the tower 4, and each pair may be twisted relative to one another. An angle α between the damping direction R1 of container 12 and a damping direction R3 of container 17 may be between 30 and 60°, in particular 45°. An angle β between the damping direction R2 of container 16 and a damping direction R4 of container 18 may be between 30 and 60°, in particular 45°. For example, all containers 12, 16, 17, 18 are intersected by the middle axis 15.

(46) Several of such pairs of containers 12, 16, 17, 18 may be placed of one another at the upper end 8, in particular on top, of the tower 4, and each pair may be twisted relative to one another. This has the advantage that effective damping in a plurality of directions may be ensured.

(47) FIG. 4 shows schematically the cross-section II-II from FIG. 1 of a further embodiment of the tower 4. In contrast to FIG. 3, the containers 12, 16 are arranged parallel to each other forming a gap G1 in between. This means that damping directions R1, R2 are essentially parallel to each other. The containers 12, 16 are arranged in the same horizontal plane E which is essentially perpendicular the middle axis 15 (see FIG. 2). Further, containers 17, 18 are in particular also arranged parallel to each other and underneath containers 12, 16. In particular, a gap G2 is arranged between the containers 17, 18. The damping directions R1, R2 are arranged perpendicular to the damping directions R3, R4. The middle axis 15 is arranged between the containers 12, 16 and between the containers 17, 18 such that a central hollow space 19 is provided between the containers 12, 16, 17, 18.

(48) Cables 20, 21, 22, 23, 24 extend through the central hollow space 19 along the middle axis 15. In particular, a central cable 24 intersects the middle axis 15. This has the advantage that a center of the tower 4 is not blocked. Thus, the cables 20, 21, 22, 23, 24 have an ideal location in case of a rotation of the nacelle 3 relative to the tower 4 (yaw movement). At least one essentially free hanging cable 20, 21, 22, 23, 24 is provided which may freely twist caused by yaw movement of the nacelle 3. A lift area 25 may be provided at a radially outer boundary area of the inner space 11. Alternatively, the lift area 25 may be provided along the middle axis 15, wherein the lift area extends through the central hollow space 19. In particular, a ladder area 26 is provided inside the inner space 11 at the wall 9.

(49) The containers 12, 16, 17, 18 are placed in a fixed position, e.g. resting on support such as a platform or support beams (not shown) connected to the tower 4. In particular, in an alternative embodiment such support could also be designed to be movable, i.e. able to turn (0-360 deg.) in order to optimize the damping effect in accordance with a given prevailing (but changing) wind direction. The movement may be directly related to the yaw movement of the nacelle 3, or work independently. The latter is in particular useful when the yaw function of the nacelle 3 is damaged. Optimal damping is crucial especially at high wind speeds if the nacelle 3 is not facing towards the wind (for an upwind turbine).

(50) The containers 12, 16 have for example the same distance to the middle axis 15 (see FIG. 2) and thus are balanced regarding a center of the tower 4 when locking from above. Also, the containers 17, 18 have for example the same distance to the middle axis 15 (see FIG. 2) and thus are balanced regarding the center of the tower 4.

(51) FIG. 5 shows schematically the cross-section II-II from FIG. 1 of a further embodiment of the tower 4. In contrast to FIG. 4, the containers 12, 16, 17, 18 protrude from the wall 9 towards the outer environment 10 of the wind turbine 1. Further, the length L of the container 12, 16, 17, 18 is larger than the inner diameter D of the wall 9. Thus, the containers 12, 16, 17, 18 extends out of an outer skirt of the tower 4

(52) Alternatively, the containers 12, 16, 17, 18 may in principle also be attached to an outer skirt of the tower 4, i.e. one or more individual containers 12, 16, 17, 18 or pairs of containers 12, 16, 17, 18 may be placed at various locations around the tower 4.

(53) FIG. 6 shows a schematic perspective view of a plurality of containers 12, 16, 17, 18, 27, 28 and the central cable 24 located between the containers 12, 16, 17, 18, 27, 28. In contrast to FIG. 4, a further pair of containers 27, 28 is provided underneath the containers 17, 18. The containers 27 28 are arranged parallel to the containers 12, 16. For example, the containers 17, 18 are stacked on the containers 27, 28 and the containers 12, 16 are stacked on the containers 17, 18. Moreover, further pairs of containers (not shown) may be stacked on the containers 12, 16. Each container 12, 16, 17, 18, 27, 28 is provided as a damper system.

(54) FIG. 7 shows a longitudinal section VII-VII from FIG. 4 of the container 12. As shown in FIG. 4 the fluid 29 and the damping body 30 are arranged inside the container 12. The damping body 30 is immersed in the fluid 29, and is configured to move inside the container 12, wherein the fluid 29 and the damping body 30 are configured to damp oscillations of the wind turbine 1. In particular, the container 12 and the damping body 30 are configured such that a full rotation of the damping body 30 inside the container 12 is prevented. Thus, rolling friction is essentially prevented. Sliding friction has the advantage over rolling friction that more kinetic energy may be transferred into thermal energy when comparing the same moving path 35 of the damping body 30. In particular, the moving path 35 extends essentially from the end face 13 to the end face 14 and vice versa. A length A of the damping body 30 is larger than the height H of an inner space 31 of the container 12 containing the damping body 30.

(55) The container 12 comprises a floor face 37 (or floor wall) having a sliding surface 32 for the damping body 30, wherein the sliding surface 32 has a curved shape. The sliding surface 32 is concave when looking from above such that the damping body 30 is arranged inside a potential well. As shown in FIG. 7 the damping body 30 is arranged at the lowest point 34 of the sliding surface 32 which may be seen as position of rest for the damping body 30. Gravitation G forces the damping body 30 towards this rest position which is arranged midway between the end face 13 and the end face 14 and thus is a center position of the container 12. Further, a ceiling face 36 (or ceiling wall) of the container 12 may also have a curved shape. The ceiling face 36 is concave when looking from above. The ceiling face 36 is arranged opposite to the floor face 37. In some circumstances, the ceiling face 36 may also be a sliding surface interacting with the sliding body 30. The inner space 31 is surrounded by the end faces 13, 14, the floor face 37, the ceiling face 36 and side walls 57, 58 (see FIG. 16).

(56) In particular, the inner space 31 may have a curved shape. A sliding surface 33 of the damping body 30 may have a curved shape. In particular, the damping body 30 is provided with a curved bottom face 38 comprising the sliding surface 33. Thus, in case of a curved sliding surface 32 a larger contact area between the sliding surface 32 and the sliding surface 33 of the damping body 30 may be achieved.

(57) At least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95% or even more of the inner space 31 of the container 12 is filled with the fluid 29. A damping effect may be achieved when the damping body 30 moves through the fluid 29 while displacing the fluid 29. Further, the fluid 29 itself sloshes e.g. against the end faces 13, 14 and thus provides a further damping effect. Optionally, further damping may be achieved by sliding of the sliding surface 33 of the damping body 30 on the sliding surface 32 of the container 12.

(58) Alternatively, the damping body 30 may float on the fluid 29 (see FIG. 8) such that the sliding surface 33 is in some instances not or permanently not in contact with the sliding surface 32 or the floor face 37. Thus, essentially no sliding friction would occur between the sliding surfaces 32, 33. In particular, the longitudinal section of the damping body 30 may be arch-shaped. The damping body 30 and the container 12 may have a similar curvature as to provide a smooth sliding motion from one end face 13 to the other end face 14 when the wind turbine 1 is oscillating.

(59) The damping body 30 is capable to move, in particular to slide, within the container 12 from the end face 13 to the end face 14 in counteractive response to the tower oscillations. The moving path 35 of the damping body 30 is dictated by the shape and length L of the container 12 which may be fully filled with the fluid 29 (e.g. after the damping body 30 has been placed) or only partly filled with fluid 29. When the wind turbine 1 oscillates, i.e. moves in one direction away from its initial position, the damping body 30 and the fluid 29 will move opposite to this direction. As wind directions obviously change and the container 12 for example is placed in a fixed and locked position, it is advantageous to use at least two or more of these containers 12, 16, 17, 18, 27, 28 (see FIG. 2 to FIG. 6). When arranging containers 12, 16, 17, 18, 27, 28 perpendicular to one another, it is possible to cover an optimal damper system irrespectively of the wind direction (and thus the tower oscillation direction).

(60) FIG. 8 shows the longitudinal section VII-VII from FIG. 4 of a further embodiment of the container 12. In contrast to FIG. 7, the longitudinal section of the damping body 30 is essentially rectangular. Moreover, the ceiling face 36 and the floor face 37 are essentially flat. The inner space 31 of the container 12 comprises the height H which is constant along the length L of the container 12. A longitudinal section of the inner space 31 is rectangular.

(61) FIG. 9 shows the longitudinal section VII-VII from FIG. 4 of a further embodiment of the container 12. In contrast to FIG. 8, the damping body 30 comprises a curved bottom face 38. The bottom face 38 is convex when looking from below. Moreover, the container 12 comprises a curved floor face 37. Further, the inner space 31 of the container 12 comprises the height H which is not constant along the length L of the container 12. The height H decreases from the lowest point 34 of the container 12 towards both end faces 13, 14.

(62) FIG. 10 shows the longitudinal section VII-VII from FIG. 4 of a further embodiment of the container 12. In contrast to FIG. 9, the ceiling face 36 has a curved shape. The ceiling face 36 is concave when looking from above.

(63) FIG. 11 shows the longitudinal section VII-VII from FIG. 4 of a further embodiment of the container 12. In contrast to FIG. 10, the inner space 31 of the container 12 comprises the height H which is constant along the length L of the container 12. Further, a top face 39 of the damping body 30 has a curved shape. The top face 39 is concave when looking from above.

(64) FIG. 12 shows the longitudinal section VII-VII from FIG. 4 of a further embodiment of the container 12. In contrast to FIG. 11, the ceiling face 36 comprises a flat portion 40 arranged at one side (right-side) of the ceiling face 36 and a flat portion 41 arranged the other side (left-side) of the ceiling face 36. A height H1 of the inner space 31 at the flat portion 40 decreases towards the end face 13. A height H2 of the inner space 31 at the flat portion 41 decreases towards the end face 14. The height H of the inner space 31 between the flat portions 40, 41 may be essentially constant.

(65) The heights H1, H2 of the container 12 vary, in particular such that the height gradually decreases towards the end faces 13, 14. Thus, cross-sectional areas of the container 12 gradually decrease towards the end faces 13, 14. This has the advantage that when the wind turbine 1 moves in one direction the damping body 30 and liquid 29 move in a counteractive direction such that the damping body 29 pushes parts of the liquid 29 in front of it creating a liquid “buffer zone” at the respective end face 13, 14.

(66) The liquid “buffer zone” will slow and stop the damping body 30 as it moves towards the end face 13, 14. In particular, the damping body 30 is so designed that it essentially matches the container cross-section but remain free moving so as to enable the damping body 30 to push towards the liquid 29 without too much liquid 29 simply just flowing across the damping body 30 since this reduces the “buffer zone” effect.

(67) Alternatively, or additionally, an end-stop or breaking mechanism (not shown) at both end faces 13, 14 may be provided for preventing the damping body 30 from damaging the end faces 13, 14 of the container 12 because great force may occur due to collisions between the damping body 30 and the end faces 13, 14. Such end-stops may comprise compressible material, e.g. a rubber material, or high friction material placed at any side of the container 12.

(68) FIG. 13 shows the longitudinal section VII-VII from FIG. 4 of a further embodiment of the container 12. In contrast to FIG. 12, the damping body 30 is shown at a position which is near to the end face 13 while moving towards the end face 13 (see broken arrow 44). Further, the ceiling face 36 comprises a curved portion 42 instead of the flat portion 40 and a curved portion 43 instead of flat portion 41. Furthermore, the top face 39 of the damping body 30 is essentially flat. Moreover, the damping body 30 has an essentially trapezoidal longitudinal section, wherein the bottom face 38 is curved. The damping body 30 comprises end faces 45, 46 which are averted from each other. Further, an end face 45 of the damping body 30 faces the end face 13 of the container 12. Furthermore, an end face 46 of the damping body 30 faces the end face 14 of the container 12. As shown in FIG. 13, when the damping body 30 moves towards the end face 13, fluid 29 is dammed between an end face 45 of the damping body 30 and the end face 13 of the container 12 e.g. forming a fluid front.

(69) Furthermore, a fluid flow 47 flows contrary to the movement (see arrow 44) of the damping body 30 between the bottom face 38 and the floor face 37 causing an increase of fluid friction and thus an increased damping effect. Moreover, a fluid flow 48 may flow contrary to the movement (see arrow 44) of the damping body 30 between the top face 39 and the ceiling face 36 causing an increase of fluid friction and thus an increased damping effect. This effect may also occur between side walls 57, 58 (see FIG. 16) of the container 12 and side faces 55, 56 (see FIG. 16) of the damping body 30.

(70) In particular, any air caught between the fluid front and damping body 30 would also contribute to this counter active effect towards the movement (see arrow 44).

(71) FIG. 14 shows detail view XIV from FIG. 13 of a further embodiment of the container 12. In contrast to FIG. 13, the container 12 comprises an end portion 49 and the damping body 30 comprises an end portion 50 for fitting into the end portion 49 of the container 12, wherein the container 12 and the damping body 30 are configured such that fluid 29 is dammed between the end face 45 of the damping body 30 and the end face 13 of the container 12 when the end portion 50 of the damping body 30 fits into the end portion 49 of the container 12.

(72) Moreover, the end portion 49 comprises a contact surface 51 and the end portion 50 comprises a contact surface 52, wherein the contact surface 52 is configured to touch the contact surface 51 for defining an end position of the damping body 30 inside the container 12. In particular, the end portion 49 forms essentially a negative form of the end portion 50. The contact surfaces 51, 52 are arranged essentially perpendicular to the floor face 37 and/or the bottom face 38.

(73) The end portion 50 is shaped such that it essentially does not touch any surface of the end portion 49 apart from the floor face 37, the contact surface 51 and for example side walls 57, 58 (see FIG. 16). This design may in the end position prevent the damping body 30 from getting stuck between the ceiling face 36 and floor face 37 of the container 12.

(74) FIG. 15 shows the longitudinal section VII-VII from FIG. 4 of a further embodiment of the container 12. The container 12 is a closed structure for keeping the fluid 29 inside the inner space 31. However, the container 12 may comprise an opening 53 at the ceiling face 36 for placing the fluid 29 and the damping body 30, in particular from above, inside the container 12. Moreover, this opening 53 may be used for service purposes. Further, a cap 54 may be provided for closing the opening 53.

(75) The container material could be any material, e.g. a metal casing or made of a composite material or the like. The damping body 30 is a durable high-density material, e.g. a metal such as iron or lead. A heavy damping body 30 is provided to get a better damping effect. In particular, the damping body 30 is easily grinded or polished to provide a smooth sliding surface 33 to ease the sliding movement. The damping body 30 comprises an outer coating or cover material for achieving a reduced friction such as Teflon or other polymeric material.

(76) In an alternative embodiment, the damping body 30 is placed on (e.g. a plate) or within a box (e.g. a casing) that may provide a low friction contact point between the container 12 and damping body 30. Further, the materials should be chosen as not to deteriorate or erode over time under the influence of the fluid 29 in the container 12 because the sliding movement may increase such effects. The fluid is e.g. an oil which may prevent the damping body 30 from getting in contact with the container 12 to a great extend upon its sliding movement.

(77) In particular, the damping body 30 may be a solid structure provided as one piece element, but can also be made of separate elements stacked next or on top of one another and joined together to form one structure.

(78) In particular, the fluid 29 may be water optionally comprising a number of different agents e.g. salts. The agent is sodium chloride because it is environmentally harmless and because the solubility of sodium chloride in water hardly changes with the temperature so that crystallization will not occur in the container 12. Sodium chloride both lowers the freezing temperature of the water and increases the density.

(79) The agent is zinc chloride and/or ferrous sulphate and/or ferrous nitrate having a cost advantage. Further, the agent may by glycerol. As fluid 29 oils may be used. Examples of such oils could be a mineral, animal or vegetable oil. Such oil fulfills at least one of the following properties:

(80) i) higher density than water,

(81) ii) non-flammable,

(82) iii) low volatility,

(83) iv) low freezing point,

(84) v) of a viscosity that, a) provides a free-flowing fluid 29 mass with a relatively quick response to the oscillations, b) allows the damping body 30 to slide easily—even at low temperatures, or c) sufficiently high to effectively contribute to the “buffer zone” effect and assist in slowing down the damping body 30 (end-stop effect).

(85) The container 12 is placed on a platform or support beams designated to be attached to the tower 4 or the nacelle 3. The time of placement can be done after a given tower 4 has been placed on a wind turbine foundation (on- or off-shore), but pre-assembled in that section before the tower 4 is installed.

(86) FIG. 16 shows a cross-sectional view XVI-XVI from FIG. 7 of a further embodiment of the container 12, wherein the container 12 and the damping body 30 are intersected. The container 12 has an elongated shape, wherein a length L of the container 12 is at least two, three, four, five, six, seven, eight, nine or even ten times larger than a width W and/or height V of the container 12. In particular, a cross-section of the damping body 30 fills at least 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95% or 98% of a cross-section of the container 12. The damping body 30 comprises side faces 55, 56 which are averted from each other and arranged essentially perpendicular to the top face 39 and/or the bottom face 38. Further, the container 12 comprises a side wall 57 facing the side face 55 and a side wall 58 facing the side face 56. The damping body 30 has essentially a rectangular cross-sectional shape. The container 12 has essentially a rectangular cross-sectional shape.

(87) FIG. 17 shows the cross-sectional view XVI-XVI from FIG. 7 of a further embodiment of the container 12. In contrast to FIG. 16, both the damping body 30 and the container 12 have a quadratic cross-sectional shape.

(88) FIG. 18 shows the cross-sectional view XVI-XVI from FIG. 7 of a further embodiment of the container 12. In contrast to FIG. 16, the bottom face 38 and the floor face 37 are roof shaped. The damping body 30 has a pentagonal cross-sectional shape.

(89) FIG. 19 shows the cross-sectional view XVI-XVI from FIG. 7 of a further embodiment of the container 12. In contrast to FIG. 16, the bottom face 38 is convex when looking from below and the floor face 37 is concave when looking from above.

(90) FIG. 20 shows the cross-sectional view XVI-XVI from FIG. 7 of a further embodiment of the container 12. In contrast to FIG. 16, the side faces 55, 56 are concave when looking thereon. Further, side walls 57, 58 are convex when looking from the inner space 31.

(91) FIG. 21 shows the cross-sectional view XVI-XVI from FIG. 7 of a further embodiment of the container 12. In contrast to FIG. 16, the bottom face 38 and the top face 39 are convex when looking thereon. Further, the ceiling face 36 and floor face 37 are concave when looking from the inner space 31.

(92) FIG. 22 shows the cross-sectional view XVI-XVI from FIG. 7 of a further embodiment of the container 12. In contrast to FIG. 16, the bottom face 38 is convex when looking thereon. Further, floor face 37 is concave when looking from the inner space 31. The top face 39 has a triangular cavity in the cross-sectional view. Further, the ceiling face 36 is adapted to the top face 39.

(93) FIG. 23 shows the cross-sectional view XVI-XVI from FIG. 7 of a further embodiment of the container 12. In contrast to FIG. 16, the damping body 30 comprises a recess 59 at the bottom face 38 and the container 12 comprises a guiding element 60 at the floor face 37 which interacts with, in particular protrudes in, the recess 59 for guiding the damping body 30 along the length L of the container 12. The guiding element 60 has a trapezoidal cross-sectional shape. The bottom face 38 is adapted to the guiding element 60.

(94) FIG. 24 shows the cross-sectional view XVI-XVI from FIG. 7 of a further embodiment of the container 12. In contrast to FIG. 23, two of such guiding elements 60 at the floor face 37 and two of such recesses 59 at the bottom face 38 are provided, wherein the guiding elements 60 have a triangular cross-sectional shape.

(95) FIG. 25 shows the cross-sectional view XVI-XVI from FIG. 7 of a further embodiment of the container 12. In contrast to FIG. 24, three of such guiding elements 60 and three of such recesses 59 are provided. The guiding elements 60 are provided at the side walls 57, 58 and the floor face 37. The recesses 59 are provided at side faces 55, 56 and the bottom face 38.

(96) FIG. 26 shows the cross-sectional view XVI-XVI from FIG. 7 of a further embodiment of the container 12. In contrast to FIG. 24, the top face 39 is concave when looking from above and the bottom face 38 is convex when looking from below. Further, the ceiling face 36 and the floor face 37 are adapted respectively.

(97) FIG. 27 shows the cross-sectional view XVI-XVI from FIG. 7 of a further embodiment of the container 12. In contrast to FIG. 23, four of such guiding elements 60 and four of such recesses 59 are provided. The guiding elements 60 are provided at the side walls 57, 58 and two guiding elements 60 are provided at the floor face 37. The corresponding recesses 59 are provided at the side faces 55, 56 and the bottom face 38. The guiding elements 60 and the recesses 59 are rounded.

(98) FIG. 28 shows the cross-sectional view XVI-XVI from FIG. 7 of a further embodiment of the container 12. In contrast to FIG. 23, the guiding element 60 is dovetail shaped, wherein the recess 59 is adapted thereto.

(99) FIG. 29 shows the cross-sectional view XVI-XVI from FIG. 7 of a further embodiment of the container 12. In contrast to FIG. 20 each side wall 57, 58 comprises a guiding element 60 and each side face 55, 56 comprises a corresponding recess 59.

(100) The guiding elements 60 may be named rail system which extend along the length L of the container (in total or in part). The function may be to guide the damping body 30 during sliding within the container 12. The guiding elements 60 may also be characterized as sidewall protection means and/or sliding pads for the damping body 30. Such guiding elements 60 may be placed along the inner space 31 of the container 12 at any side, and would thus prevent the damping body 30 from scraping against the walls. Such guiding elements 60 may be provided separately from the container 12 or may be formed inside the container 12 as integral part thereof. The guiding elements 60 are exchangeable in part or in total.

(101) FIG. 30 shows the cross-sectional view XVI-XVI from FIG. 7 of a further embodiment of the container 12. In contrast to FIG. 16, the damping body 30 and the container 12 have a circular cross-sectional shape. Moreover, four guiding elements 60 are dispersed along a circumference of the container 12 touching the damping body 30. The guiding elements 60 taper towards the damping body 30.

(102) FIG. 31 shows the cross-sectional view XVI-XVI from FIG. 7 of a further embodiment of the container 12. In contrast to FIG. 27, the ceiling face 36 comprises a further guiding element 60. Moreover, recesses 59 are not provided at the damping body 30.

(103) FIG. 32 shows the cross-sectional view XVI-XVI from FIG. 7 of a further embodiment of the container 12. In contrast to FIG. 16, the bottom face 38 is concave when looking from below and the floor face 37 is convex when looking from above.

(104) FIG. 33 shows the longitudinal section VII -VII from FIG. 4 of a further embodiment of the container 12. The container 12 further comprises a compensation container 61. The compensation container 61 is connected to the container 12 by means of two ducts 62, 63. A first duct 62 is connected to the container 12 close to the first end face 13. A second duct 63 is connected to the container 12 close to the second end face 14. Each duct 62, 63 comprises a valve 64, 65. The valves 64, 65 control the flow speed of the fluid 29 and thereby the damping body 30. The damping body 30 can be immersed in the fluid 29 completely or only partly.

(105) FIG. 34 shows the longitudinal section VII-VII from FIG. 4 of a further embodiment of the container 12. The container 12 according to FIG. 34 differs from the container 12 according to FIG. 33 in that it does not have a compensation container 61 but only one duct 66 with a valve 67. The duct 66 is connected to the container 12 both close to the first end face 13 and to the second end face 14 thereof.

(106) FIG. 35 shows the longitudinal section VII-VII from FIG. 4 of a further embodiment of the container 12. The container 12 according to FIG. 35 differs from the container 12 according to FIG. 34 in that there is not only provided one damping body 30 but more than one, for example three. The damping bodies 30 are in the form of rollers or cylinders and can rotate inside the container 12. The fluid 29 can be controlled by one or more valves 67.

(107) FIG. 36 shows the longitudinal section VII-VII from FIG. 4 of a further embodiment of the container 12. The container 12 according to FIG. 36 differs from the container 12 according to FIG. 35 in that there is provided a separate end-stop-valve 68 which is connected to the ceiling face 36 by means of a duct 69.

(108) It is understood that all features described regarding the container 12, the damping body 30 and the fluid 29 also apply mutatis mutandis to the containers 16, 17, 18, 19, 27, 28.

(109) 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.

(110) 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.