Foundation equipment for offshore wind turbine tower

Abstract

The invention relates to an infrastructure for an offshore wind turbine tower. The device comprises a first body (1), a support body (3) attached to the first body (1), a second body (2) and a plurality of legs (4) attached to the second body (2). The support body (3) has a cylindrical interior and is configured to provide support and connection to the wind turbine tower (10). The first body (1) comprises a central portion (5) connected to the support body (3) and a plurality of hollow arms (6) connected to the central portion (5). Each hollow arm (6) comprises a through-hole (7) configured to allow a leg (4) to pass through the through-hole. The volume and weight of the first body (1) are configured to provide a buoyancy of at least 20% of the weight of the entire device during idle load, the weight of the first body (1) being less than 8% of the weight of the entire device. The leg (4) and / or the first body (1) has a locking system configured to lock the relative position between the leg and the first body.

Description

Technical Field

[0001] The invention belongs to the technical field of structures for supporting wind turbine towers in offshore installations. Background Art

[0002] When installing offshore wind turbine towers, a suitable system for foundation laying and stability needs to be provided.

[0003] There are a number of different methods and devices for this purpose. Based on the way the structure achieves stability, they can be divided into four categories: semi-submersible platforms, TLPs, SPARs or barges.

[0004] Semi-submersible platforms are platforms with stability, which compensate for their high center of gravity by providing a high metacentric radius due to their high buoyancy inertia. They are characterized by good offshore performance, but their size increases based on the development of wind turbine power (increasingly large), making it difficult to find construction docks and ports with the required size and draft.

[0005] A TLP (Tension Leg Platform) is a platform that gets its stability from its anchoring system, which is tensioned because the main structure has a hydrostatic thrust greater than its own weight. This type of platform has excellent offshore performance, but the disadvantage is the difficulty of installation due to the large tendons it has.

[0006] SPAR platforms are stable platforms due to their center of gravity being lower than the center of the hull. Due to their low surface and high natural period, they are transparent to the influence of waves and therefore have superior offshore performance.

[0007] Similar to semi-submersible platforms, barges gain stability due to their large buoyancy inertia and have poor offshore performance.

[0008] The invention described below is based on the concept of a SPAR type structure. In addition to the installation problems inherent to such platforms, it should be noted that many of these platforms lack the stability required for transportation and require additional equipment (barges or cranes) for transportation and installation, which is not the case with the present invention.

[0009] The present invention provides an alternative solution to the known solutions. Summary of the invention

[0010] As described above, the present invention provides an alternative solution for laying offshore tower foundations by means of an apparatus for laying foundations according to claim 1. Preferred embodiments of the invention are defined in the dependent claims.

[0011] Unless otherwise defined, all terms (including technical and scientific terms) used herein should be understood as commonly used in the art. It should also be understood that, unless explicitly defined herein, commonly used terms should also be understood as commonly used in the relevant art, rather than idealized or overly formalized meanings.

[0012] In this document, the term "comprise" and its variations (eg, "comprising", etc.) should not be understood in an exclusive sense; that is, these terms should not be understood to exclude the possibility that the described and defined content may include other elements, steps, etc.

[0013] In a first inventive aspect, the invention relates to an apparatus for supporting an offshore wind turbine tower, the apparatus comprising a first body, a support body attached to the first body, a second body and a plurality of legs attached to the second body, wherein

[0014] a support body having a cylindrical interior defining a tower axis and configured to provide support for and connection to a wind turbine tower;

[0015] The first body includes a central portion connected to the support body and a plurality of hollow arms connected to the central portion, wherein each hollow arm extends radially from the central portion and includes a first surface perpendicular to the tower axis and a second surface parallel to the first surface, wherein the first surface of the hollow arm is contained in a first reference plane and the second surface of the hollow arm is contained in a second reference plane, wherein the first reference plane is farther from the second body than the second reference plane;

[0016] Each hollow arm includes a through hole extending from the first surface to the second surface, wherein the through hole is configured to allow a leg to pass through the through hole;

[0017] The volume and weight of the first body are configured to provide a buoyancy of at least 20% of the weight of the entire device when unladen, and the weight of the first body is less than 8% of the weight of the entire device;

[0018] The first body has a first ballast management element to selectively allow water to enter / flow out of the first body;

[0019] The second body has a first surface and a second surface, the first surface and the second surface are both parallel to the first reference plane and the second reference plane, wherein the first surface is closer to the first body than the second reference plane;

[0020] The second body has a ballast management element to selectively allow water to enter / leave the second body; and

[0021] The leg and / or the first body has a locking system configured to lock the relative position between the leg and the first body.

[0022] The first body is a hollow body which provides a high buoyancy-to-weight ratio. In fact, the first body contributes at least 20% of the buoyancy of the entire device, but its weight is less than 8% of the entire device.

[0023] Furthermore, the weight of the second body is much greater than the first body and, in fact, the second body is submerged several meters below the first body to help improve the stability of the device by providing a stable position of the offshore wind turbine tower without adding elements providing buoyancy inertia on the surface. The device according to the invention is designed to be completely submerged once in operation so that the support body will be the only element outside the water surface.

[0024] The ballast management elements in both the first and second bodies allow a good customization of the final position and the hydrostatic balance of the device. It also enables easier disassembly of the device in case of maintenance tasks or in case of final removal.

[0025] In a particular embodiment, the leg length is equal to or greater than the sum of: the distance between the first reference plane and the second reference plane; 55% of the distance between the first reference plane and the second surface of the second body. In this way, the distance between the first body and the second body can be large enough to actively contribute to increasing the stability of the assembly.

[0026] In a particular embodiment, the through-hole comprises a plurality of rollers to ensure smooth sliding of the legs inside the through-hole.

[0027] The legs are moved for several meters so that the second body reaches its final position below sea level. These rollers therefore prevent the legs from being damaged while the operation is being carried out.

[0028] In a particular embodiment, the central portion is hollow and has a main cross-section with an area larger than the cross-section of any of the hollow arms, wherein the main cross-section contains the tower axis and the cross-section of the hollow arm is measured according to a plane perpendicular to the tower axis and perpendicular to the first surface of the hollow arm.

[0029] A stable suspension mode is thus formed. The central part receives auxiliary elements and support mechanisms (crane, maintenance access, lights, etc.).

[0030] In case of an arm, the respective extension axis refers to the axis starting from the central part and extending along the arm.In case of a central part, any plane cutting the central part along the vertical middle axis can be used.

[0031] In certain embodiments, each leg includes a stopper configured to cooperate with each through hole to prevent the leg from being removed from the first body.

[0032] The stop provides an advantageous way of defining a final position of the second body relative to the first body.

[0033] In certain embodiments, the leg and / or the first body has a locking system configured to lock the relative position between the leg and the first body.

[0034] The locking system is configured to prevent the relative position between the first body and the second body from being changed during operation of the device.

[0035] In a particular embodiment, the locking system comprises a hydraulic cylinder.

[0036] These hydraulic cylinders provide the strong force that ensures the correct locking of the two elements.

[0037] In a particular embodiment, the second body has a beveled hollow polygonal shape, preferably a beveled hollow triangle shape.

[0038] This structure provides an optimal ratio between weight, volume and stability.

[0039] In a particular embodiment, each chamfered vertex of the triangle receives one of the legs.

[0040] Since the legs are located at an outer distance from the center of the first part, the device operates in a stable manner.

[0041] In a particular embodiment, the support body comprises a plurality of planar protrusions arranged in a radial manner, wherein a dimension of the support body in the axial direction is greater than a dimension thereof in the radial direction.

[0042] The central element generally has a cylindrical shape. The vertical axis is thus defined by the axis of the cylinder. The protrusions extend radially from the axis such that the height of the protrusions is greater than the length, thereby making the system stable in yaw.

[0043] In certain embodiments, the first body includes a planar panel extending from a base of the first body closer to the second body.

[0044] The planar plate allows for control of fore-aft instabilities, increasing the device's natural period of resistance to fore-aft oscillations by adding mass and damping, thereby increasing the overall stability of the device.

[0045] In certain embodiments, the apparatus further comprises a mooring line attached to the first body.

[0046] In a particular embodiment, the leg has a cylindrical shape. However, in other cases, the leg can have a polygonal cross section, for example a triangle. This is advantageous when it is not possible to bend a plate to form the leg.

[0047] In a particular embodiment, the leg includes a first guide element and the through hole includes a second guide element configured to cooperate with the first guide element to guide movement of the leg through the through hole.

[0048] Optimum sliding is thus ensured, preventing play and movements in axes other than the axis of movement.

[0049] In a particular embodiment, one of the guide elements is a groove and the other guide element is a protrusion configured to slide through the groove. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to complete the description and for the purpose of better understanding the present invention, a set of drawings is provided. The drawings are an integral part of the specification and illustrate embodiments of the present invention, which should not be understood as limiting the scope of the present invention, but only as examples of how the present invention can be implemented. The illustrations include the following drawings:

[0051] Figure 1 An operational diagram of an apparatus for laying a wind turbine tower foundation according to the invention is shown.

[0052] Figure 2 A detail of a guiding system of a leg relative to a hole of a first body in a device for laying a wind turbine tower foundation according to the invention is shown.

[0053] Figures 3 to 5 Different steps of assembly of the device according to the invention are shown.

[0054] Figure 6 The length of the device legs is shown in relation to the size of the device.

[0055] The reference numerals used in the drawings are as follows:

[0056] 1 The first subject

[0057] 2 Second subject

[0058] 3 Support

[0059] 4 Legs

[0060] 5 The central part of the first body

[0061] 6 Arm of the first body

[0062] 7 Through hole of first body

[0063] 8 Mooring rope

[0064] 9 Yaw stabilization protrusion

[0065] 10 Wind Turbine Towers

[0066] 11 Front and rear stabilizer plates

[0067] 12 Sliding rollers

[0068] 13 Guide protrusion

[0069] 14 Guide groove

[0070] 15 Hydraulic cylinder

[0071] 20 First surface of the second body

[0072] 21. Second surface of the second body

[0073] 30 Tower axis

[0074] 100 First reference plane of the first body

[0075] 101 Second reference plane of the first body DETAILED DESCRIPTION

[0076] The embodiments are described in detail to enable those skilled in the art to implement and apply the systems and processes described herein. It is important to understand that the embodiments can be provided in a variety of alternative forms and should not be construed as limited to the examples described herein.

[0077] Accordingly, although the embodiments can be modified in various ways and in various alternative forms, the drawings illustrate specific embodiments and are described in detail below as examples. This document is not intended to be limited to a specific disclosed form. On the contrary, all modifications, equivalents, and alternatives within the scope of the appended claims must be included. In the drawings and detailed description, the elements of the exemplary embodiments are always labeled with the same reference numerals where appropriate.

[0078] Figure 1 An operational diagram of an apparatus for laying a wind turbine tower foundation according to the invention is shown.

[0079] In this figure the installation can be seen without the wind turbine tower and the reference waterline.

[0080] The device includes a first body 1 and a second body 2 .

[0081] Above the first body there is a support body 3, which is attached to the first body 1. The support body 3 will be used to receive a wind turbine tower, so its interior is cylindrical. The support body 3 defines a tower axis 30, which is used as a reference to define the orientation of the other elements.

[0082] The first body 1 comprises a central part 5 connected to the support 3. The central part 5 is also cylindrical and coaxial with the support 3. The wind turbine tower is thus anchored in the centre of the device for laying the foundation.

[0083] In addition to the central part 5, the first body 1 comprises a plurality of arms 6 connected to the central part 5. Each hollow arm 6 extends radially from the central part 5 and comprises an upper surface perpendicular to the tower axis and a lower surface parallel to the first surface. The upper surface of the hollow arm is contained in a first reference plane 100 and the lower surface of the hollow arm is contained in a second reference plane 101. It can be seen that the first reference plane 100 is farther from the second body 2 than the second reference plane 101. The arms 6 are hollow to allow adjustment of the float provided by the first body 1.

[0084] The device further comprises a second body 2. The second body 2 is intended to be fully submerged at a depth of several meters relative to the first body 1, while the first body 1 is intended to be located near (but below) sea level. The second body 2 has a first surface 20 and a second surface 21, both of which are parallel to the first reference plane and the second reference plane, wherein the first surface 20 is closer to the first body 1 than the second surface 21.

[0085] The movement of the second body 2 relative to the first body 1 is performed by a series of cylindrical legs 4. These legs 4 are integrally fixed to the second body 2 and are introduced into through holes 7 present in the first body 1, extending from the upper surface of each arm to the lower surface of the same arm. During the transfer of the device, the first and second bodies 1, 2 are very close to each other, so that the legs 4 protrude several meters from the first body 1. Once the device reaches the foundation area, the second body 2 is lowered, bringing with it the legs 4 integrally attached to the second body 2, so that these legs 4 slide through the through holes present in the first body 1. Once the final position is reached, the device includes a locking system that locks the relative position of the legs 4 and the first body 1 in the operating position, so that the waves and external forces to which the device is subjected do not cause the legs 4 to move relative to the first body 1. This can cause the distance between the first body 1 and the second body 2 to change, so that the operation of the device for laying foundations is impaired.

[0086] Both the first body 1 and the second body 2 have ballast management elements to selectively allow water to enter / exit the respective body. It is thus possible to control the floatation of both bodies during the transport, assembly, sinking and final anchoring of the device.

[0087] The volume and weight of the first body 1 are configured to provide a buoyancy of 25% of the weight of the entire device when unloaded, and the unloaded weight of the first body 1 is about 4% of the weight of the entire device. In contrast, the unloaded weight of the second body 2 is about 90% of the weight of the device. This achieves a very low center of gravity and a very high center of buoyancy, increasing the stability of the system.

[0088] Furthermore, the central portion 5 is hollow and has a main cross-section (a cross-section perpendicular to its main body axis) with an area greater than the cross-section of any of the hollow arms (measured perpendicular to the axis along which each arm extends).

[0089] The second body 2 has a chamfered hollow triangular shape, so that each chamfered vertex of the triangle receives one of the legs 4. Due to this distribution of the internal hollowness, a better stability with respect to the weight is achieved.

[0090] Each leg 4 includes a stopper configured to cooperate with each through hole 7 to prevent the second body 2 from being disengaged from the first body 1 as the second body 2 descends and the protruding distance of each leg 4 decreases.

[0091] It can also be seen that there are two stabilizing elements in this figure.

[0092] First, a plurality of planar protrusions 9 are arranged radially from the support body 3, and their size in the axial direction of the support body is larger than their size in the radial direction. The protrusions extend radially from the axis of the support body 3 so that their height is greater than their length, thereby stabilizing the system when yawed.

[0093] Secondly, a planar plate 11 extends from the bottom of the first body 1. The planar plate allows the fore-aft instability to be controlled, increasing the natural period of the device's resistance to fore-aft oscillations by adding mass and damping, thereby increasing the overall stability of the device.

[0094] Figure 2 is a cross-sectional view of some of the elements constituting the device according to the invention.

[0095] In the drawings, the hollow arm 6 is cut away for a better understanding of the elements included in the drawings.

[0096] As shown in the previous figures, the leg 4 is introduced into the through hole 7 of each of the arms 6. The inside of the arm has rollers 12 which ensure the correct sliding of the leg, without play or movement in directions other than the vertical. Wear of the leg caused by external forces from said axis is thus prevented.

[0097] In this figure, it is also possible to see the tenon and groove of the leg 4. This guidance is achieved by the cooperation of a vertical protrusion 13 included in the leg and a groove 14 included in the through hole 7, the groove being suitable for receiving the protrusion 13 and guiding the leg 4 thereby.

[0098] In addition to the above, there is a hydraulic locking cylinder 15 which is intended to fix the position of the leg 4 when it reaches the final position.

[0099] Figures 3 to 5 Different steps of assembly of the device of the invention are shown.

[0100] Figure 3 Shown is an assembly formed by an apparatus for laying a foundation and a wind turbine tower 10 already assembled on land onto a support 3 .

[0101] Being able to use land installations and being able to install the equipment in port areas reduces the logistical process and eliminates any offshore operations and the inherent risks between two bodies with different relative movements due to different buoyancy.

[0102] Furthermore, a variety of tugboats can transport the structure to the installation site.

[0103] like Figure 4 As shown, the ballast means will be activated to fill the second body 2 with water. This will cause the immersion of the second body 2 and the sliding of the legs 4 through the through holes of the first body 1, assuming that the legs 4 are integrally attached to the second body 2 and will therefore descend with it.

[0104] Figure 5 It is shown how the legs 4 are anchored relative to the first body 1 once the second body 2 has reached its operating position, so that the distance between the first body 1 and the second body 2 remains constant. The first body 1 is then partially ballasted so that it is then submerged. Finally, mooring lines 8 are arranged which anchor the first body 1 in the seabed.

[0105] Figure 6 It shows how the leg length LL is greater than the sum of: the distance L1 between the first reference plane and the second reference plane, and 55% of the distance L2 between the first reference plane and the second surface of the second body 2:

[0106] LL>L1+0.55·L2

[0107] Thus, after the structure is fully deployed, the remaining visible length is equal to or greater than 55% of the distance between the first reference plane and the second surface of the second body. This ensures that once deployed and installed at sea, the distance between the first body and the second body actively contributes to the stability of the device.

Claims

1. An apparatus for supporting a tower of a wind turbine, the apparatus comprising a first body (1), a support body (3) attached to the first body (1), a second body (2) and a plurality of legs (4) attached to the second body (2), wherein The support body (3) has a cylindrical interior defining a tower axis (30) and is configured to provide support for and connection to a wind turbine tower (10); The first body (1) comprises a central part (5) connected to the support body (3), and a plurality of hollow arms (6) connected to the central part (5), wherein: Each hollow arm (6) extends radially from the central portion (5) and comprises a first surface perpendicular to the tower axis and a second surface parallel to the first surface, wherein the first surface of the hollow arm is contained in a first reference plane (100) and the second surface of the hollow arm is contained in a second reference plane (101), wherein the first reference plane (100) is farther from the second body (2) than the second reference plane (101); Each hollow arm (6) comprises a through hole (7) extending from the first surface to the second surface, wherein the through hole (7) is configured to allow the leg (4) to pass through the through hole; The volume and weight of the first body (1) are configured to provide a buoyancy of at least 20% of the weight of the entire device when unloaded, and the weight of the first body (1) is less than 8% of the weight of the entire device The first body (1) has a first ballast management element to selectively allow water to enter / flow out of the first body The second body (2) has a first surface (20) and a second surface (21), both of the first surface and the second surface are parallel to the first reference surface and the second reference plane, wherein the first surface (20) is closer to the first body (1) than the second surface (21); The second body (2) has a ballast management element to selectively allow water to enter / flow out of the second body The leg (4) and / or the first body (1) has a locking system, which is configured to lock the relative position between the leg and the first body.

2. The device according to claim 1, wherein The length of the leg portion is equal to or greater than the sum of: a distance between the first reference plane and the second reference plane; and 55% of a distance between the first reference plane and the second surface of the second body.

3. The device according to any one of the preceding claims, wherein: The through hole (7) comprises a plurality of rollers to ensure smooth sliding of the legs inside the through hole (7).

4. The device according to any one of the preceding claims, wherein: The central portion (5) is hollow and has a main cross-section with an area larger than the cross-section of any of the hollow arms, wherein the main cross-section contains the tower axis and the cross-section of the hollow arm is measured according to a plane perpendicular to the tower axis and perpendicular to the first surface of the hollow arm.

5. Apparatus according to any one of the preceding claims, wherein: Each leg (4) comprises a stopper, which is configured to cooperate with each through hole (7) to prevent the leg (4) from coming out of the first body (1).

6. Apparatus according to any one of the preceding claims, wherein: The locking system comprises a hydraulic cylinder (15).

7. Apparatus according to any one of the preceding claims, wherein: The second body (2) has a beveled hollow polygonal shape, preferably a beveled hollow triangle shape.

8. Apparatus according to any one of the preceding claims, wherein: Each chamfered vertex of the triangle receives one of the legs (4).

9. Apparatus according to any one of the preceding claims, wherein: The support body (3) comprises a plurality of planar protrusions (9) arranged in a radial manner, wherein the dimension of the support body in the axial direction is greater than its dimension in the radial direction.

10. Apparatus according to any one of the preceding claims, wherein: The first body (1) includes a planar plate (11) extending from a base portion of the first body closer to the second body (2).

11. Apparatus according to any one of the preceding claims, further comprising a mooring line (8) attached to the first body.

12. Apparatus according to any one of the preceding claims, wherein: The leg (4) has a cylindrical shape.

13. Apparatus according to any one of the preceding claims, wherein: The leg (4) comprises a first guide element (13), and the through hole (7) comprises a second guide element (14), which is configured to cooperate with the first guide element (13) to guide the movement of the leg (4) through the through hole (7).

14. The device according to claim 13, wherein: One of the guide elements is a groove and the other guide element is a protrusion configured to slide through the groove.

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