Mooring System for a Floating Wind Turbine

Abstract

The invention relates to a system comprising: a foundation element that has a universal joint, wherein the universal joint has a first universal joint element connected to the foundation element for conjoint rotation and a second universal joint element which is rotatable about the longitudinal axis of the first universal joint element by carrying out a rotation about its own longitudinal axis; a floating wind turbine; and a mooring line. One end of mooring line is connected to the foundation element a first connector connected to the second universal joint element for conjoint rotation and the other end of which is connected to the floating wind turbine a second connector rotatably mounted on the floating wind turbine. The system also includes a controller which, on the basis of the rotational position of the floating wind turbine about the foundation element, brings about the adoption of a rotational position of the second connector rotatably mounted on the floating wind turbine; wherein the rotational position of the second connector rotatably mounted on the floating wind turbine corresponds to the rotational position of the second universal joint element about its own longitudinal axis, which rotational position geometrically corresponds to the rotational position of the floating wind turbine about the foundation element.

Claims

1. A system having: a foundation element having a universal joint, wherein the universal joint, has a first axle stub connected to the foundation element in a rotationally fixed manner and a second axle stub which is rotatable about the longitudinal axis of the first axle stub by carrying out a rotation about its own longitudinal axis, a floating wind turbine, a mooring line, one end of which is connected to the foundation element by a first connector connected in a rotationally fixed manner to the second axle stub and the other end thereof is connected to the floating wind turbine a second connector rotatably mounted on the floating wind turbine, and a controller which causes the assumption of a rotational position of the second connector rotatably mounted on the floating wind turbine in dependence on the rotational position of the floating wind turbine about the foundation element, wherein the rotational position of the second connector rotatably mounted on the floating wind turbine corresponds to the rotational position of the second axle stub about its own longitudinal axis, which corresponds geometrically to the rotational position of the floating wind turbine about the foundation element.

2. The system according to claim 1, wherein the controller is configured, taking into account the alignment of the longitudinal axis of the floating wind turbine relative to the foundation element, to cause the assumption of the rotational position of the second connector rotatably mounted on the floating wind turbine.

3. The system according to claim 2, wherein the controller has a compass for determining the alignment of the longitudinal axis of the floating wind turbine relative to the foundation element.

4. The system according to claim 1, wherein the controller has a sensor for position determination by a global satellite navigation system.

5. The system according to claim 1, wherein the controller has a rotary drive for rotating the rotatably mounted second connector.

6. The system according to claim 1, wherein the floating wind turbine has an electrical coupling for connecting to a power cable connected to an electrical grid arranged outside the wind turbine and having a first electrical plug connector connected to the power cable, and having a second electrical connector complementary to the first electrical connector and connected to an electrical grid located within the wind turbine, wherein the plug connectors are movable relative to one another for forming and disconnecting an electrical plug connection and are configured so as to be rotatable relative to one another in order to overcome the power cable connected to the first plug connector.

7. The system according to claim 1, wherein the controller has a drive holding the floating wind turbine (100) at a predetermined distance from the foundation element (10).

8. The system according to claim 1, wherein the foundation element (10) is a pile foundation, a suction bucket foundation or a heavyweight foundation.

9. The system according to claim 1, wherein the universal joint is a conventional universal joint with intersecting joint rotary axes or an eccentric universal joint.

10. The system according to claim 1, further comprising a bellows housing the universal joint.

11. The system according to claim 10, wherein the bellows has a restoring force forcing the axle stub of the universal joint into an extended arrangement.

12. The system according to claim 10, wherein the foundation element has a plug connector configured for connection to a power cable for connection to an electrical grid arranged outside the wind turbine.

13. The system according to claim 1, wherein the foundation element has a bushing accommodating a cable connected to an electrical grid arranged outside the wind turbine.

14. The system according to claim 10, wherein the universal joint has a bushing accommodating a power cable connected to an electrical grid arranged outside the wind turbine.

15. The system according to claim 14, wherein the bushing is arranged centrally in the axle stub forming the universal joint and an intermediate piece connecting the axle stubs to one another.

16. The system according to claim 14, wherein the first connector and/or the second connector is a pulley about which the mooring line is guided.

17. The system according to claim 16, further comprising another connector arranged parallel to the first connector and to the second connector and designed as a pulley around which another mooring line is guided.

18. The system according to claim 16, wherein the mooring line is designed in two parts, wherein the two sections of the mooring line are connected to one another by a connector.

19. The system according to claim 18, wherein the connector is configured as a buoyant buoy.

20. The system according to claim 18, wherein the connector has on one of its surfaces a first connection for a first power cable connecting the connector to an electrical grid arranged outside the wind turbine and, on a surface opposite this surface, a second connection for a second power cable connecting the connector to the floating wind turbine.

21. The system according to claim 18, the length of the section connecting the foundation element to the connector corresponds to at least the depth of water in the region of the foundation element.

22. The system according to claim 18, wherein the mooring line is a cable.

Description

[0033] The invention is explained in greater detail below with reference to a particularly preferred embodiment shown in the attached drawings, in which:

[0034] FIG. 1 shows an overview of a particularly preferably designed system according to the invention with a particularly preferably designed floating wind turbine (A) anchored to the bottom of a body of water by means of a foundation element, a detailed view of a particularly preferably designed connector (B) connecting the mooring lines attached to the foundation to the wind turbine, and a detail view of the foundation element (C) anchored in the bottom of the body of water;

[0035] FIG. 2 shows a perspective view of a particularly preferably configured foundation element with a conventional universal joint with intersecting joint rotary axes (A) and with an eccentric universal joint (B);

[0036] FIG. 3 shows the connection of the mooring lines connected to the foundation element to the floating wind turbine in a perspective view (A) and in a sectional view (B);

[0037] FIG. 4 shows a particularly preferably designed floating wind turbine before the anchoring thereof to the bed of the body of water in an overview (A) and in a detail view in the region of the surface of the body of water (B);

[0038] FIG. 5 shows the connector shown in FIG. 4B and connecting the foundation element to the floating wind turbine in a perspective view from above (A) and from below (B);

[0039] FIG. 6 shows a sectional view of the connector in the decoupled state (A) and in the coupled state (B);

[0040] FIG. 7 shows a side view of the floating wind turbine anchored on the bed of the body of water in two positions caused by different wind directions; and

[0041] FIG. 8 shows a plan view of the floating wind turbine in four positions caused by different wind directions.

[0042] FIG. 1 shows an overview of a particularly preferably designed system according to the invention with a particularly preferably designed floating wind turbine (A) anchored to the bottom of a body of water by means of a foundation element, a detailed view of a particularly preferably designed connector (B) connecting the mooring lines attached to the foundation to the wind turbine, and a detail view of the foundation element (C) anchored in the bottom of the body of water. In particular, FIG. 1A shows a floating wind turbine 100 that is anchored to a bed of a body of water by means of the foundation element 10 and which is oriented into the wind during operation and clamps the mooring line 30 connecting to the foundation element 10. FIG. 4C shows in this regard a detail view of the foundation element 10 anchored in the bed of the body of water. During operation of the floating wind turbine 100, the angle assumed by the mooring line 30 relative to the bottom of the body of water is substantially the same as the angle assumed between the mooring line routed between the connection of the mooring line 30 to the wind turbine 100 and the tower of the floating wind turbine 100 and the foundation of the floating wind turbine 100.

[0043] As a special feature of this exemplary embodiment, the first section of the mooring line 30 connected to the foundation element 10 is not directly connected to the wind turbine 100, but to a connector 200 designed as a buoy. As FIG. 4B shows in a detail view, the connection of the first section of the mooring line 30 to the floating wind turbine 100 takes place indirectly via the connector 200 which is connected to the second section of the mooring line 130 connected to the floating wind turbine 100. It is also provided that the power cable 40 leading to the foundation element 10 is connected to the connector 200 by means of a plug connection, wherein another power cable 40 electrically connects the connector 200 to the floating wind turbine 100. The functions and tasks of the individual elements are described in detail below.

[0044] FIG. 2 shows a perspective view of a first exemplary embodiment of the foundation element 10 with a conventional universal joint with intersecting joint rotary axes (A), and a second exemplary embodiment of the foundation element with an eccentric universal joint (B). In particular, FIG. 1A shows a foundation element 10 designed as a pile foundation for the anchoring of a floating wind turbine 100 to a bed of body of water. The foundation element 10 has a conventional universal joint 20 on its upper side, which is formed from two axle stubs 22, 24 which are connected to one another by means of a spherical intermediate piece 26. In this case, the one axle stub 22 is designed to be flexurally rigid and connected to the foundation element 10 in a rotationally fixed manner, and the other axle stub 24 is configured for connection to a mooring line 30 connecting the foundation element 10 to the floating wind turbine.

[0045] In particular, the other axle stub 24 has, as a first connecting means 50, two pulleys 50 formed parallel to each other, each of which accommodates a mooring line 30 in the form of a cable guided around the pulleys 50 acting as idler pulleys. A bushing which accommodates a power cable 40 is provided between the pulleys 50 or cables 30. The power cable 40 is connected to the floating wind turbine and incorporates it into an electrical grid. For this purpose, the foundation element 10 specifically has a connection which is configured for connection to a power cable 40 and creates an electrical connection between the power cable 40 leading away from the foundation element 10 which is designed in particular as a submarine cable, and the power cable 40 leading from the wind turbine to the foundation element 10.

[0046] The conventional universal joint 20 shown in FIG. 2A has a maximum bending angle of approximately 35-45?, whereas the eccentric universal joint 20 shown in FIG. 2B has a maximum bending angle of up to 90? with a cuboid intermediate piece 26.

[0047] FIG. 3 shows the connection of the mooring lines 30 connected to the foundation element to the floating wind turbine 100 in a perspective view (A) and a sectional view (B). The connection of the mooring line 30 to the underside of the floating wind turbine 100 is designed in particular as a counterpart to the foundation element 10. In particular, a connecting means 120 designed as two pulleys 120 is provided here and connects two mooring lines 30 to the wind turbine 100, wherein the second connecting means 120 is rotatably mounted relative to the wind turbine 100 by means of the slewing gear 110. The deflecting pulleys 120 are in particular fixedly connected to the slewing gear 110 via a support frame so that the loads of the floating wind turbine 100 from wind and wave are transmitted to the mooring system and thereby to the foundation element 10 on the bed of the body of water.

[0048] The slewing gear 110 has a bushing for the power cable 40 arranged between the pulleys 120, wherein a rotary drive 140 which causes a rotation of the slewing gear 110 is provided. The rotary drive 140 is controlled by a controller which is configured with a device for detecting the rotational position of the floating wind turbine 100 in relation to the foundation element 10. In this regard, the second connecting means 120 can be selectively rotated in a controlled manner via the rotary drive 140 to prevent twisting of the connecting elements 30 and the power cable 40 when the horizontal alignment of the floating wind turbine 100 is changed. To determine the required rotational angle which the rotary drive 140 must rotate the second connecting means 120 so that the connecting means 30 leading up to the foundation element 20 is aligned straight, i.e., without rotation, a direction sensor 150 is attached to the floating wind turbine in order to determine the rotational position of the floating wind turbine 100 around the foundation element 10. It must be taken into account that the universal joint 20 performs an uneven transmission of rotation when the latter is bent.

[0049] FIG. 4 shows the floating wind turbine 100 shown in FIG. 1 before the anchoring thereof to the bed of the body of water in an overview (A) and in a detail view in the region of the surface of the body of water (B). In particular, FIG. 4A shows a first section of a mooring line 30 fastened to the foundation element 10, the free (upper) end of which is fastened to a connector 200 designed as a buoy. In this case, the first section of the mooring line 30 has a length which corresponds at least to the depth of the body of water in the region of the foundation element 10 placed in the bed of the body of water. In any case, the buoyant connector 200 has fastening means on its underside for fastening the first section of the mooring line 30 and the power cable 40. FIG. 4B shows a detail view of FIG. 4A in which it can be seen that the connector 200 in the shown example floats on the water's surface, and the second (upper) section of the mooring line 130 is temporarily fastened to the wind turbine 100. The floating wind turbine 100 has the second connecting means 120 to which the second section of the mooring line 130 is pre-attached and entrained so that the wind turbine 100 can be connected at the water's surface to the connector 200 and therefore indirectly to the foundation element 10.

[0050] The particularly preferably provided connector 200 is shown in more detail in FIG. 5 in a perspective view from above (A) and from below (B). The connector 200 designed as a buoy consists substantially of a floating body 210 to which additional connecting means for fastening the sections of the mooring line 30, 130 are connected. Centrally, there is a watertight junction box 220, 220 into which the power cables 40, 40 are inserted from above and below and electrically connected to each other.

[0051] FIG. 6 shows a sectional view of the particularly preferably provided connector 200 in the decoupled state (A) and in the coupled state (B). The floating body 210 is designed in particular such that it carries the weight of the first section of the mooring line 30 and the lower power cable 40 and can hold the entire unit on the water's surface. To release the connection between the foundation element 10 on the bed of the body of water and the floating wind turbine 100, the second section of the mooring line 130 is mechanically released from the connecting buoy 200, and the electrical connection of the power cable 40 is disconnected. For this purpose, the plugs 45 of the three phases accommodated in the junction box 220 are pulled out of the sockets 220.

[0052] FIG. 7 and FIG. 8 serve to explain the geometric relationships basically represented by the system. In this regard, FIG. 7 shows a particularly configured system according to the invention in a side view in which the floating wind turbine 100 is shown in two opposite positions with respect to the alignment relative to the foundation element 10 at the bed of the body of water. It can be seen that the floating wind turbine 100 moves around the foundation element 10 depending on the wind direction, wherein the mooring line 30 and the power cable align accordingly and are held taut by the wind and wave loads. Under these movements, the mooring line 30 and the universal joint 20 on the foundation element 10 tilt spatially about the vertical axis according to the orientation. The angle between the vertical (shown dashed) and the alignment of the mooring line 30 corresponds to the bending angle ? of the second axle stub 24 of the universal joint 20.

[0053] Finally, FIG. 8A shows a particularly configured system according to the invention in a plan view, wherein a floating wind turbine 100 connected to a foundation element 10 by means of a mooring line 30 is shown in four different positions offset by 90? in each case. The floating wind turbine 100 rotates about the foundation element 10 depending on wind and waves, wherein the mooring line 30 is held taut by the wind and wave load. In addition, the submarine cable 40 connected to the wind turbine 100 can be seen, which conducts the electrical energy generated by the wind turbine 100 to the transfer station.

[0054] These four positions shown in FIG. 8A are shown in FIG. 8B in a detailed plan view of the foundation element 10. Based on the alignment of the pulleys 50, it can be seen that the second axle stub 24 of the universal joint 20, when rotated about the longitudinal axis of the first axle stub 22, simultaneously performs a rotation about its own axis so that the pulleys 50 at the positions of the second axle stub rotated by 90? to the previous position are also rotated by 90?. In so doing, the rotational position of the second axle stub 24 about the first axle stub 22 is indicated by the angle epi, wherein the rotational position of the second axle stub 24 about its own axis is given by the angle 92. In other words, the angle between the instantaneous direction of rotation of the mooring line 30 in the horizontal plane and the direction of rotation of the pivot axes of the universal joint 20 is defined as deviation angle 1, wherein the angle of rotation of the second axle stub of the universal joint of the side connected to the mooring line 30 is denoted by 92. The rotary drive 140 must rotate the second connecting means 120 by this angle 92 to prevent the mooring line 30 and the power cable 40 from twisting.

[0055] The basis is that when a conventional universal joint is angled by the bending angle ? and rotated in this state, the angle of rotation ?.sub.2 of the output shaft deviates from the angle of rotation ?.sub.2 of the input shaft. The following relationship applies:

[00002]${?}_2=\arctan \left(\frac{\tan {?}_1}{\cos ?}\right)$