FLOATING PLATFORM DEVICE FOR A WIND TURBINE TOWER AND ASSEMBLY METHOD

Abstract

The present invention relates to a device for the support and foundation of a wind turbine tower. Said device comprises a main body (1) made at least partially of concrete. It also comprises a transition part (2) attached to the main body (1) and a plurality of installation elements (3) located on the main body. The transition part (2) comprises a housing (4) for installing a wind turbine tower, and each installation element (3) comprises a through hole (5) for installing an anchoring tendon.

Claims

1. A device for the support and foundation of a wind turbine tower, the device comprising: a main body made at least partially of concrete, wherein the main body is configured to provide a hydrostatic buoyancy force greater than the weight of the main body; a transition part attached to the main body, the transition part comprising a housing for installing a wind turbine tower; a plurality of installation elements located on the main body, with each installation element comprising a through hole; the device being characterized in that the main body has a prismatic shape, and the transition part also has a prismatic shape, with the axis of the prism of the main body coinciding with the axis of the prism of the transition part; the main body comprises a first polygonal-shaped base, a second polygonal-shaped base parallel to the first base, a side wall joining the first base and the second base defining an inner volume comprised between the first base, the second base and the side wall, and a plurality of ribs comprised in the inner volume, with each rib being in contact with at least one of the bases; the prism of the main body has beveled vertexes, where the installation elements project from the bevels.

2. The device according to claim 1, wherein at least 90% of the main body is made of concrete.

3. The device according to claim 1, wherein the installation elements comprise a housing intended for receiving an anchoring tendon head.

4. (canceled)

5. (canceled)

6. (canceled)

7. (canceled)

4. The device according to claim 1, wherein the transition part traverses the second base and has a portion inserted into the inner volume, with some ribs being in contact with said portion comprised within the inner volume.

5. The device according to claim 1, further comprising a ladder located on the side wall, a horizontal platform located on the second base, which connects the ladder with the transition part; an access platform at the base of the tower located in the transition part; a vertical ladder in the transition part which connects the horizontal platform with the access platform at the base of the tower; a rail-mounted crane, located on the second base, configured for moving parallel to the horizontal platform.

6. The device according to claim 1, wherein the main body comprises a plurality of tanks, where each tank comprises a ballast valve, with one of the ballast valves being adapted to be attached to a manifold; each tank comprises a vent valve; and each tank comprises a high-pressure valve.

7. An installation method for installing a device according to claim 1, the method comprising the steps of placing a wind turbine tower in the transition part; performing a first ballasting of the device for transport; transporting the assembly formed by the device and the wind turbine tower to an offshore installation site, where a series of anchoring tendons are transported on the second base; performing a second ballasting of the platform device for the installation of the anchoring tendons; installing the anchoring tendons in the installation elements of the device; and gradually deballasting the device.

8. The method according to claim 7, wherein the step of deballasting the device is performed by calculating the total weight of the device and the wind turbine tower and deballasting until the buoyancy force is such that said total weight reaches a design value comprised between 25% and 35% of the buoyancy force.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0062] To complete the description and help to better understand the invention, a set of figures is attached to the description. These figures are part of the description and illustrate a particular example of the invention, which is not to be interpreted as being limiting of the scope thereof, but rather as a mere example of how the invention can be carried out. This set of figures comprises the following:

[0063] FIG. 1 shows a particular embodiment of a device for the support and the foundation of a wind turbine tower according to the invention.

[0064] FIG. 2 shows an alternative embodiment of a device for the support and the foundation of a wind turbine tower according to the invention.

[0065] FIG. 3 shows a view of the device of FIG. 1 in which the upper base has been eliminated.

[0066] FIG. 4 shows a construction detail of the foundation device, in which access elements for accessing the platform and a stowage alternative the tendons on deck are observed.

[0067] FIGS. 5a to 5c show a series of steps in an installation method for installing the device described in the preceding figures.

[0068] In order to help better understand the technical features of the invention, the mentioned figures are accompanied by a series of reference numbers which, in an illustrative and non-limiting manner, represent the following:

TABLE-US-00001 1 Main body 2 Transition part 3 Installation elements 4 Housing in the transition part 5 Through hole in the installation element 6 Housing in the installation element 7 Ribs 8 Ladder 9 Tendon stowage 10 Horizontal platform 11 Lower base 12 Upper base 13 Side wall 14 Access platform 15 Vertical ladder 16 Crane

DETAILED DESCRIPTION OF THE INVENTION

[0069] FIG. 1 shows a particular embodiment of a device for the support and the foundation of a wind turbine tower according to the invention.

[0070] As can be seen in the figure, the device comprises: [0071] a main body 1 made of reinforced concrete; [0072] a transition part 2 attached to the main body 1; and [0073] a plurality of installation elements 3 located on the main body 1.

[0074] The device shown in the figure is intended for being the support and the foundation of a wind turbine tower installed offshore. To that end, the transition part 2 comprises a housing 4 for installing the wind turbine tower. This process can be performed on land to take the device-tower assembly to the point of installation.

[0075] The main body 1 is intended for providing the stability needed during transport and installation of the wind turbine tower. This main body has a triangular prismatic shape with beveled vertexes. Therefore, it is a hexagonal prism. Therefore, there is a first lower base 11, a second upper base 12 parallel to the first base and a side wall 13 joining the first base and the second base, with an inner volume (not visible in this figure) comprised between the first base, the second base and the side wall being defined.

[0076] The installation elements 3 are positioned in the beveled vertexes, each of said elements comprising a through hole 5 and a housing 6 intended for receiving an anchoring tendon head, since these installation elements will serve as guidance and support for the installation of the anchoring tendons.

[0077] The transition part 2 also has a prismatic shape, with the axis of the prism of the main body coinciding with the axis of the prism of the transition part. The wind turbine tower is thereby successfully placed in the center of the installation device, allowing better stability during transport and installation.

[0078] FIG. 2 shows an alternative location of the installation elements 3, which are located in the upper area, projecting from the second base 12 of the main body. This location is especially advantageous in the case of concrete, which works under tension, because when the anchoring tendons are inserted into these installation elements 3 and tensioned, the stresses caused in the concrete are tensile stresses of the installation element 3 on the side wall 12. Therefore, this embodiment is especially advantageous.

[0079] FIG. 3 shows a view of the device of FIG. 1 in which the upper base has been eliminated. A plurality of ribs 7 comprised in the inner volume (which is visible in this figure) are thereby exposed, each rib 7 being in contact with at least one of the bases.

[0080] As can be observed in this figure, the transition part 2 traverses the second base and has a portion inserted into the inner volume, being some ribs 7 in contact with said portion comprised within the inner volume.

[0081] There is also a series of ballast valves, adapted for being attached to a manifold located on deck. These ballast valves will receive the ballast hose when ballasting the main body and, by means of pipes, are directed to each tank in order to fill same.

[0082] Furthermore, there are also vent valves, which are used to expel the air existing inside the tank when said tank is being filled with the ballast water.

[0083] Lastly, there are also high-pressure valves which are used to introduce compressed air into the tanks to empty out the ballast water in the deballasting process.

[0084] FIG. 4 shows a construction detail of the foundation device in which access elements for accessing the platform are observed.

[0085] First, there is a ladder 8 located on the side wall 13. The stowage of the tendons 9, located on the second base 12, can also be observed.

[0086] A horizontal platform 10 which connects the ladder 8 with the transition part 2 is also observed on the second base 12. Furthermore, this horizontal platform 10 continues into an access platform 14, intended for providing access to the base of the tower located in the transition part 2. Lastly, there is a vertical ladder 15 in the transition part 2 itself, which connects the horizontal platform 10 with the access platform at the base of the tower.

[0087] To facilitate tower installation tasks, or tasks for handing the maintenance or repair material, there is also a rail-mounted crane 16 located on the second base 12, configured for moving across the horizontal platform 10.

[0088] FIGS. 5a to 5c show a series of steps in an installation method for installing the device described in the preceding figures.

[0089] FIG. 5a shows a first installation step, in which the assembly formed by the foundation device and a wind turbine tower installed in the transition part is assembled at port and, after a first ballasting of the device, is towed to the installation site. Durante this towing step, the anchoring tendons are transferred on the second base of the foundation device, so no auxiliary installation means are needed.

[0090] FIG. 5b shows a subsequent installation step in which the anchoring tendons are inserted into the corresponding holes of the main body, and a first ballasting of the device takes place for the prestressing of the anchoring tendons.

[0091] In these cases, the ballasting operation is carried out by connecting a ballast hose between the support vessel and the platform. The support ship will pump the ballast water into the corresponding tank by means of the ballast inlet valve until optimal filling is reached. Subsequently, by means of manipulating the manifold it will be directed to the next tank to be filled in the ballasting sequence.

[0092] Lastly, FIG. 5c shows how selective deballasting of the device for tensioning the anchoring tendons is performed.

[0093] The deballasting operation is performed by closing the low-pressure vent valves and injecting pressurized air through the high-pressure circuit until exceeding the hydrostatic pressure. This allows the ballast tank to be over-pressurized such that the increase in pressure can cause the height of the water to rise until reaching the height of the manifold, and it can be intended for offshore use.

[0094] During this step of deballasting the device, first the total weight of the device and the wind turbine tower is calculated, and then the deballasting of the device takes place until the buoyancy force is such that said total weight reaches a design value comprised between 25% and 35% of the buoyancy force.