Apparatus and method for connecting a wind turbine tower to a foundation

Abstract

The present invention relates to a metal ring for connecting a metal wind turbine tower to a concrete foundation, the ring comprising: a first disc having an annular shape around an axis and including a plurality of anchor holes, each anchor hole allowing the passage of a preloaded cable for anchoring the first disc to the concrete foundation; and a second disc spaced apart from the first disc and including a plurality of clamp holes, each clamp hole positioned opposite a corresponding anchor hole in the first disc, allowing a clamping tool to be engaged with the clamp holes and for applying tension to the preloaded cable passing through the anchor holes opposite the clamp holes. The first and second discs are connected to each other by a first generally annular metal spacer to form a single member.

Description

Technical Field

[0001] The present disclosure relates to an apparatus and method for connecting a metallic structure to a concrete structure. More specifically, it relates to the connection of a metallic wind turbine tower to a gravity or floating concrete foundation.

Background Art

[0002] An offshore wind turbine consists of a wind turbine having a rotor and a generator, and is disposed at the top of a tower. The tower itself is fixed to a structure (or foundation) that is fixed to the seabed or floats on water. The foundation is generally formed of concrete.

[0003] To attach a metallic wind turbine tower to a concrete foundation, generally, a device for connecting the tower to the foundation is used. The connecting device fixed between the tower and the foundation must be able to withstand large stresses. These stresses can be mechanical (high moment loads, horizontal forces, and vertical forces during installation of the tower on the foundation and during operation). The stresses are also induced by the marine environment.

[0004] Document number 345416B1 proposes an apparatus for connecting a metallic tower to a concrete foundation, including a plurality of metallic rings separated by a formwork filled with concrete. This connecting device includes two rings that must be sequentially arranged and fixed, which requires a plurality of operations to connect the tower to the foundation, and is accompanied by the installation of the connection being relatively time-consuming and complicated. Also, this connecting device does not allow the cable to be tensioned after the connecting device is placed in a predetermined position.

[0005] Document CN105673354A also proposes a connecting device that similarly uses two metallic rings separated by one or more formworks filled with concrete. The connection structure in this document is subject to the same limitations as the device of number 345416B1.

[0006] Document WO2017 / 108043A1 proposes a device for connecting a metal tower, which is a tower resting on a metal ring, to a concrete foundation using two rows of bolts. To secure the connection device, the bolts penetrate the foundation, extend to the tower, and are fixed to another metal ring. Therefore, it is not possible to prestress the cables after the connection device is installed. The same bolts are used to fix the tower to the metal ring and the metal ring to the concrete foundation, which requires a particularly large dimensional design for these bolts.

[0007] It is advantageous to find solutions that eliminate all or part of the restrictions described above. [Overview of the project]

[0008] One objective of the invention is to solve at least one of the problems described above.

[0009] For this purpose, in one aspect of the invention, a metal ring is proposed for connecting a T-flange at the base of a metal wind turbine tower to a concrete foundation, the ring being generally annular in shape around the axis of the tower, and including: - An anchor disc having a plurality of anchor holes, each anchor hole being adapted to allow a prestress cable to pass through in order to anchor the anchor disc in a concrete foundation, and - A fixed disk positioned at a distance from an anchor disk by a first spacer, comprising a plurality of clamping holes, each of which is positioned opposite to each anchoring hole of the anchor disk, and which allows a clamping tool to be engaged with the clamping holes to apply tension to a prestress cable passing through the anchoring hole opposite to the clamping hole; The anchor disk and the fixed disk are connected to each other by a first generally annular metal spacer; The anchor disc, fixing disc, and spacer are arranged around the axis and form a single component; The fixed disk further includes through-holes adapted to allow the tower to be secured to the fixed disk.

[0010] Therefore, this connecting ring consists of a single metal element having a shape that allows it to conform to the shape of the foundation. Furthermore, the ring is very easy to manufacture.

[0011] Furthermore, the ring can be easily installed in a single step. It can be fully constructed before it is placed on the foundation.

[0012] Advantageously, however, optionally, the described ring shall have at least one of the following characteristics: - The anchor disc and the fixing disc are connected to each other by a second, roughly annular, metal spacer, which is centered on the axis and together with the anchor disc, fixing disc and the first spacer, forms a single component; - The first and second spacers are hollow cylindrical in shape, with one of the first and second spacers forming the first hollow cylinder and positioned radially inward relative to the anchor hole and clamp hole, and the other forming the second hollow cylinder and positioned radially outward relative to the anchor hole and clamp hole; the first and second spacers are welded to the anchor disc and the fixing disc; - The anchor disc and the fixing disc are connected to each other by multiple additional metal spacers, and each adjacent anchor hole is separated from each other by an additional spacer, which is welded to the anchor disc and the fixing disc; - The fixing disc includes a group of fixing holes, each group positioned near and surrounding each clamping hole, with two inner fixing holes positioned radially inward relative to the clamping hole and two outer fixing holes positioned radially outward relative to the clamping hole; - The ring includes multiple connecting ring corners around the axis.

[0013] In another embodiment, a connecting device is proposed that includes a ring according to any of the above embodiments and anchoring means for anchoring the ring to a concrete foundation, each of which anchoring means includes a plurality of prestress cables intended to be anchored in the concrete foundation and an anchor head for fixing the ring to the prestress cables.

[0014] In another embodiment, a wind turbine comprising a rotor, generator, tower, foundation, and the aforementioned connecting devices is proposed.

[0015] In another embodiment, a method is proposed for connecting a metal wind turbine tower to a concrete foundation using the connecting device, the method comprising the following steps: - A process of casting a concrete foundation, wherein a duct is created using metal trumpets for positioning prestress cables during the casting process; - A process of adjusting multiple leveling devices at the upper end of a concrete foundation; - The process of placing circular seals around each duct at the top of the concrete foundation; - The process of placing the ring on the leveling device such that the anchor disc faces the concrete foundation and each anchor hole is coaxial with each of the respective ducts; - The process of injecting a layer of anchoring grout between the concrete foundation and the ring; - The process of inserting prestressed cables into the duct; - The process of positioning an anchor plate and anchor head in each anchor hole and clamping a prestressed cable in each anchor hole; - The process of securing the ring to the concrete foundation using clamping tools inserted into each of the clamping holes, and then tensioning the prestressed cable at the anchor head; - injecting cementitious grout into the duct around the prestressed cable and around the anchor head; and - fixing the tower to the ring by clamping fixing means in each fixing hole of the fixing disk.

[0016] Advantageously, but optionally, the method may include the following features: - The step of fixing the ring to the concrete foundation is carried out using a tension jack.

Brief Description of the Drawings

[0017] Other features, objects and advantages of the invention will become apparent from the following illustrative description, which is non-limiting and is to be read in conjunction with the accompanying drawings, in which: [Figure 1] Figure 1 is a perspective view of a wind turbine fixed to a foundation by a connecting device in one embodiment of the present invention. [Figure 2a] Figures 2a and 2b are top views of a connecting ring in one embodiment of the present invention. [Figure 2b] Figures 2a and 2b are top views of a connecting ring in one embodiment of the present invention. [Figure 3] Figure 3 is a perspective view from above a corner of the ring in another embodiment of the present invention. [Figure 4] Figure 4 is a partial cross-sectional view along a radial plane, i.e., a plane including the central longitudinal axis of the tower (this axis is the axis of symmetry of the tower with respect to the cylindrical tower), of a device for connecting a wind turbine tower to a concrete foundation according to one embodiment of the present invention, including partial views of the tower and the foundation. [Figure 5a] Figures 5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h, 5i, 5j show the steps of a method for connecting a wind turbine tower to a concrete foundation by a connecting device according to one particular implementation of the invention. [Figure 5b]Figures 5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h, 5i, and 5j show the steps of a method for connecting a wind turbine tower to a concrete foundation by a connecting device according to one specific embodiment of the invention. [Figure 5c] Figures 5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h, 5i, and 5j show the steps of a method for connecting a wind turbine tower to a concrete foundation by a connecting device according to one specific embodiment of the invention. <, [Figure 5d] Figures 5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h, 5i, and 5j show the steps of a method for connecting a wind turbine tower to a concrete foundation by a connecting device according to one specific embodiment of the invention. [Figure 5e] Figures 5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h, 5i, and 5j show the steps of a method for connecting a wind turbine tower to a concrete foundation by a connecting device according to one specific embodiment of the invention. [Figure 5f] Figures 5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h, 5i, and 5j show the steps of a method for connecting a wind turbine tower to a concrete foundation by a connecting device according to one specific embodiment of the invention. [Figure 5g] Figures 5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h, 5i, and 5j show the steps of a method for connecting a wind turbine tower to a concrete foundation by a connecting device according to one specific embodiment of the invention. [Figure 5h] Figures 5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h, 5i, and 5j show the steps of a method for connecting a wind turbine tower to a concrete foundation by a connecting device according to one specific embodiment of the invention. [Figure 5i] Figures 5a, ,5b, 5c, 5d, 5e, 5f, 5g, 5h, 5i, and 5j show the steps of a method for connecting a wind turbine tower to a concrete foundation by a connecting device according to one specific embodiment of the invention. [Figure 5j]Figures 5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h, 5i, and 5j illustrate the steps of a method for connecting a wind turbine tower to a concrete foundation by a connecting device, relating to one specific embodiment of the invention. [Figure 6] Figure 6 is a flowchart illustrating a method for connecting a metal wind turbine tower to a concrete foundation, according to one specific embodiment of the present invention.

[0018] In all figures, identical elements are assigned the same reference numeral. [Modes for carrying out the invention]

[0019] Detailed description of the invention General description of wind turbines In the following explanation, "radial direction" refers to the direction primarily directed by vectors collinear with the radius, and "axial direction" refers to the direction primarily directed by vectors collinear with the axis of symmetry. "Inside" is used to refer to areas closer to the axis of symmetry in the radial direction, and "outside" refers to areas further away from the axis of symmetry in the radial direction.

[0020] The wind turbine E shown in Figure 1 can be a fixed, gravity, or floating wind turbine.

[0021] The wind turbine E includes a base 1 or foundation, a tower 2, means 3 for fixing the tower 2 to the base 1, also called a connecting device, and energy generating means 4.

[0022] The energy generation means 4 includes a generator 41 and a rotor 42. The generator 41 is fixed to the upper end 22 of the tower 2 and connected to the rotor 42.

[0023] The rotor 42 includes a plurality of blades 421. The rotor 42 is rotationally driven around a rotation axis Y that is perpendicular to the axis X of the tower 2. The generator 41 generates power in relation to the rotational action of the blades 421 that causes the rotor 42 to rotate relative to the generator 41.

[0024] Foundation 1 may have various shapes depending on whether the wind turbine E is an onshore wind turbine or an offshore wind turbine, and depending on the environmental conditions in which it is installed. Foundation 1 ensures the stability of the wind turbine E. Foundation 1 is advantageously made of concrete. The concrete may be of various types depending on the type of wind turbine E and the environment in which it is installed. Foundation 1 may include ballast (not shown) to stabilize the wind turbine E.

[0025] Advantageously, the foundation 1 includes a central column 11 supporting at least one wind turbine E, a lower pontoon structure 12 having at least three arms 121 arranged in a star configuration, and side columns 13 rigidly connected to the pontoon structure 12. The pontoon structure 12 protrudes from the lower part 111 of the central column 11. The side columns 13 are rigidly connected to the pontoon structure 12 at the distal portions 1221 of each arm 121. The central column 11 is preferably cylindrical and may be hollow or partially hollow. This configuration ensures good stability with respect to the foundation 1 and, consequently, to the wind turbine E.

[0026] Tower 2 extends along its axis X. Tower 2 is advantageously cylindrical or conical in shape. Preferably, Tower 2 has a circular or polygonal cross-section. Tower 2 is preferably constructed of a metallic material because it must withstand large mechanical stresses of bending and torsion. The choice of metal further allows for a reduction in the weight of the tower, facilitating its transport and installation.

[0027] Continuing to refer to Figures 1 and 4, the lower end 21 of the tower 2 is fixed to the foundation 1 by a connecting device 3. For this purpose, the lower end 21 of the tower 2, i.e., the leg of the tower 2, includes an inverted T-shaped flange 211. More specifically, the flange 211 has a radial cross-section that forms an inverted T shape. The flange 211 includes a central branch 2111 that is integrated with the wall of the tower 2, and two transverse branches 2112 that extend on both sides of this central branch 2111 at the lower end of the flange 211 in the leg of the tower 2. Elements 211, 2111, 2112, 2113, and 2114 are not visible in Figure 1, but are visible in Figure 4.

[0028] Therefore, as shown in particular in Figure 4, the transverse branches 2112 that form the flange 211 at the leg 21 of the tower 2 allow the tower 2 to be fixed to the connecting device 3. The two transverse branches 2112 extending on both sides of the central branch 2111 of the flange 211 facilitate the fixing of the tower 2 in the ring 31, and thus enable the connection of the tower 2 to the foundation 1. Thus, the flange 211 can be fixed onto the ring 31 by each of the two transverse branches 2112 on both sides of the central branch 2111, and the force can be evenly distributed on the ring 31.

[0029] As shown in Figure 4, the flange 211 includes a number of fixing holes 2113, 2114 for securing the flange 211. The fixing holes 2113, 2114 of the flange 211 are arranged at a constant radius and at equal intervals around the axis X of the tower 2. Preferably, the fixing holes 2113, 2114 are distributed in a row of holes called intrados fixing holes 2113, which are radially inward relative to the central branch 2111, and in a row of holes called extrados fixing holes 2114, which are radially outward relative to the central branch 2111. The intrados fixing holes 2113 and extrados fixing holes 2114 are located equidistant from the central branch 2111. Thus, the central branch 2111 of the flange 211 forms annular symmetry between the arrangement of intrados fixing holes 2113 and the arrangement of extrados fixing holes 2114. This makes it possible to uniformly fix the flange 211 in the ring 31 without generating a moment load on the flange 211.

[0030] Connection device The connection device 3 enables the connection of the metal tower 2 of the wind turbine E to the concrete foundation 1 of the wind turbine E.

[0031] The connecting device 3 includes a connecting ring 31. Figure 2a shows an axial view of the connecting ring 31. That is, Figure 2a shows the connecting ring 31 along axis X of the tower 2.

[0032] Advantageously, the connecting ring 31, hereafter referred to simply as the ring, is annular in shape centered on the axis X of the tower 2. Therefore, the ring 31 includes an inner rim 34 and an outer rim 35. The inner rim 34 and the outer rim 35 are coaxial with the axis X of the tower 2. The ring 31 is preferably made of metal.

[0033] In one embodiment, the ring 31 includes a single annular portion that extends around the entire axis X of the tower 2.

[0034] In another embodiment shown in Figure 2b, the ring 31 includes a plurality of joint corners 36. That is, the ring 31 is formed in a plurality of parts 36 that can be assembled together to form a ring around the axis X of the tower 2, thereby facilitating transportation and installation on the foundation 1.

[0035] As shown in Figures 2a and 3, the ring 31 includes anchor holes 3113 and fixing holes 3124. The anchor holes 3113 are configured to allow the ring 31 to be anchored to the base 1, and the fixing holes 3123 are configured to allow the ring 31 to be fixed to the tower 2.

[0036] The anchor holes 3113 and fixing holes 3124 are arranged in the ring 31 at a constant radius and at equal intervals around the axis X of the tower 2. Therefore, the anchor holes 3113 and fixing holes 3124 are distributed across the ring 31 to form annular arrangements.

[0037] Advantageously, as shown in Figure 2a, the fixing holes 3124 are grouped into the same number of groups 3125 as there are anchor holes 3113. Each group 3125 of fixing holes 3124 is arranged such that each anchor hole 3113 is surrounded in the axial direction by multiple fixing holes 3124. In each group 3125 of fixing holes 3124, at least one fixing hole 3124a, called an intrados, is positioned radially inward relative to each anchor hole 3113, and at least one fixing hole 3124b, called an extrados, is positioned radially outward relative to the anchor hole 3113.

[0038] Preferably, each group 3125 of the fixing holes 3124 is located near each anchor hole 3113, with two fixing holes 3124a, called intrados, of each group 3125 of the fixing holes 3124, located radially inward from each anchor hole 3113, and two fixing holes 3124b, called extrados, of each group 3125 of the fixing holes 3124, located radially outward from the anchor hole 3113.

[0039] Each intrados fixing hole 3124a and each extrados fixing hole 3124b are located equidistant radially from their respective anchor holes 3113. In other words, the arrangement formed by the anchor holes 3113 creates a circular symmetry between the arrangement of intrados fixing holes 3124a and the arrangement of extrados fixing holes 3124b. This makes it possible to reduce the moment load induced by the fixing of the tower in the ring 31.

[0040] Therefore, the fixing holes 3124 enable uniform and efficient fixing of the metal tower 2 to the ring 31.

[0041] Furthermore, because the central branch portion 2111 of the flange 211 and the anchor hole 3113 are coaxial and have the same radius, the forces acting on the foundation 1 and tower 2 are uniformly distributed in the connecting device 3, and no moment load is generated in the ring 31.

[0042] As shown in Figure 4, the anchor hole 3113 is configured to receive the fixing means 32, and the fixing hole 3123 is configured to receive the fixing means 33.

[0043] Figure 4 shows a radial cross-section of the connection device 3 along plane AA containing the axis of symmetry X of the tower 2. The diagram shown in Figure 4 gives a diagram of the connection device 3 along axis X1, parallel to axis X, for each of the fixing means 32.

[0044] Therefore, the connecting device 3 includes a ring 31, fixing means 32 for anchoring the ring 31 to the concrete foundation 1, and fixing means 33, such as bolts, for fixing the tower 2 to the ring 31, extending around the axis X of the tower 2.

[0045] The fixing means 32 and the fixing means 33 are configured to be arranged at a constant radius and at equal intervals within the ring 31 in the anchor holes 3113 and fixing holes 3124, respectively. In other words, the fixing means 32 and the fixing means 33 are distributed across the ring 31, forming a circular arrangement.

[0046] Advantageously, each anchoring means 32 is therefore surrounded by a plurality of fixing means 33. Optionally, for each anchoring means 32, one or more fixing means 33 are positioned radially inward relative to the anchoring means 32 on the ring 31, and one or more fixing means 33 are positioned radially outward relative to the anchoring means 32.

[0047] As shown in Figure 4, each anchoring means 32 includes at least one prestressed cable 321 and an anchor head 322. Advantageously, each anchoring means 32 includes multiple wire strands that are twisted together to form one or more prestressed cables 321. The anchor head 322 of each anchoring means 32 allows for the fixing of the ring 31 in the prestressed cable 321 of each anchoring means 32.

[0048] In one embodiment, each anchoring means 32 further includes an anchor plate 323. The anchor plate 323 is washer-shaped and supports the anchor head 322 on the ring 31. The plate 323 allows for force distribution of the anchor head 322 on the ring 31.

[0049] As shown in Figure 4, the ring 31 includes a first disk 311, a second disk 312, and at least one spacer 313, 314 configured to rigidly connect the first disk 311 and the second disk 312 and provide space between them. The ring 31 is a single member in that the first disk 311, the second disk 312 and the spacers 313, 314 are welded together.

[0050] In Figure 4, the ring 31 includes a first spacer 313 and a second spacer 314. However, the ring 31 may also include only one of the first spacer 313 or the second spacer 314.

[0051] The first disc 311 and the second disc 312 are preferably hollow, in other words, they each form a plate including their respective inner edges 3111, 3121 and their respective outer edges 3112, 3122, which are circular and coaxial with the axis X of the ring 31. The first disc 311 and the second disc 312 are also coaxial with the axis X of the ring 31.

[0052] The first disk 311 is called the anchor disk 311 because it is positioned on the side of the ring 31 which is configured to be in contact with the base 1 and bonded to the base 1 by the anchoring means 32.

[0053] The anchor disk 311 includes anchor holes 3113, as shown in Figure 2a. The anchor holes 3113 of the anchor disk 311 are distributed across the anchor disk 311 at equidistant from the axis of symmetry X of the tower 2, as shown in Figure 2a. Advantageously, the anchor holes 3113 are located at equidistant from the inner edge 3111 and the outer edge 3112 of the anchor disk 311. Thus, the ring 3 is fixed to the foundation 1 in an evenly balanced manner, and the stress is uniformly distributed across the anchor disk 311.

[0054] In particular, as shown in Figure 4, the anchor holes 3113 of the anchor disc 311 are adapted to allow the passage of one or more prestress cables 321 for fixing the first anchor disc 311 to the concrete foundation 1. The same is clearly true for all the anchor holes 3113 of the anchor disc 311. In other words, the anchor heads 322 of each anchoring means 32 fix the anchor disc 311 to each prestress cable 321 of each anchoring means 32. Thus, the ring 3 is anchored to the foundation 1 by the anchor heads 322 placed on the anchor disc 311.

[0055] As shown in Figure 4, the second disk 312 is spaced apart from the first disk 311 by the first spacer 313 and the second spacer 314. The second disk 312 is called the fixed disk 312 because it is located on the side of the ring 3 which is configured to contact the tower 2 and be fixed to it via the fixing means 33. The fixed disk 312 includes a fixing hole 3124 and a plurality of clamping holes 3123, as shown in Figure 2a.

[0056] As shown in Figure 4, each clamp hole 3123 of the fixed disk 312 is positioned in the fixed disk 312 so as to face one of the anchor holes 3113 of the anchor disk 311, in other words, each clamp hole 3123 of the fixed disk 312 is coaxial with the anchor holes 3113 of the anchor disk 311. The clamp holes 3123 are advantageously through holes. The clamp holes 3123 allow engagement of a clamping tool 5 configured to clamp the prestressed cable 321 in the anchor holes 3113 by applying tension to the prestressed cable 321 passing through the anchor holes 3113 facing each clamp hole 3123. Therefore, the clamp holes 3123 have a larger diameter than the diameter of the anchor holes 3113 because the clamping tool 5 necessarily has a larger diameter than the diameter of the prestressed cable 321 passing through the anchor holes 3113.

[0057] The fixing holes 3124 are adapted to allow the tower 2 to be fixed to the fixing disk 312 by the fixing means 32. The fixing holes 3124 are advantageously through holes.

[0058] As shown in Figure 4, the intrados fixing hole 3124a and the extrados fixing hole 3124b are configured to work in cooperation with the intrados fixing hole 2113 and the extrados fixing hole 2114 of the flange 211, respectively, to fix the tower 2 to the connection device 3.

[0059] Therefore, the arrangement for fixing the tower 2 of the wind turbine E to the ring 31 allows for the use of fixing means 33, such as bolts, that penetrate only the fixing disc 312, rather than penetrating the entire thickness of the ring 31. Thus, these fixing means 33 do not need to be excessively sized to withstand large additional loads.

[0060] The first spacer 313 and the second spacer 314 are annular in shape, preferably cylindrical. The first spacer 313 and the second spacer 314 are positioned around the axis X of the tower 2. The first spacer 313 and the second spacer 314 are hollow cylinders. The first spacer 313 is positioned radially inward relative to the second spacer 314. Both the first spacer 313 and the second spacer 314 are welded to the anchor disk 311 and the fixed disk 312 at their respective ends in the direction of the axis X of symmetry of the tower 2.

[0061] Advantageously, the first spacer 313 is welded to the anchor disc 311 and the fixed disc 312 radially inward relative to the anchor holes 3113 and clamp holes 3123 of the anchor disc 311 and the fixed disc 312, respectively. The second spacer 314 is welded to the anchor disc 311 and the fixed disc 312 radially outward relative to the anchor holes 3113 and clamp holes 3123 of the anchor disc 311 and the fixed disc 312, respectively. Furthermore, the first spacer 313 is welded to the fixed disc 312 radially outward relative to the intrados fixing hole 3114a of the fixed disc 312. The second spacer 314 is welded to the fixed disc 312 radially inward relative to the extrados fixing hole 3124b of the fixed disc 312. This enables uniform stress distribution in the ring 31.

[0062] Therefore, by securing the anchor head 322 to the anchor disk 311, the anchor head 322 is protected from the environment by the ring 31. In other words, the anchor head 322 is protected from the environment by the second disk 312, the first spacer 313, and the second spacer 314.

[0063] Furthermore, the arrangement of the anchor head 322 allows the flange 211 of the tower 2 to be fixed to the connecting device 3 without generating a moment load that could deform the ring 31. The fixing of the flange 211, which is centered on the ring 31, and the centralized positioning of the anchor hole 3113 enable uniform stress distribution throughout the ring 31 and allow the central branch portion 2111 of the flange 211 to be aligned with the anchor hole 3113.

[0064] Furthermore, the fixing holes 3124 are located in an accessible portion of the ring even after the first spacer 313 and the second spacer 314 in the anchor disk 311 and the fixing disk 312 have been welded together, i.e., when the ring 31 is formed as a single component. Therefore, the fixing means 3124 of the connecting device 3 can be positioned or replaced when the ring 31 is installed and / or after the tower 2 is positioned on the ring 31.

[0065] The ring 31 thus connects the T-flange 211 to the concrete foundation 1 at the leg 21 of the metal wind turbine tower 2: - By protecting the prestressed cable from the environment and corrosion through its direct fixation in the anchor disk 311, - Without generating any moment load between the leg portion 21 of tower 2 and the anchor hole 3113, - By distributing the force uniformly in ring 31, Make it possible.

[0066] Preferably, the ring 31 further includes a plurality of additional spacers 315. The additional spacers 315 may be radial spacers in particular. Each additional spacer 315 is welded to the anchor disc 311 and the fixing disc 312. The additional spacers 315 are also welded to the first spacer 313 and the second spacer 314. The additional spacers 315 are positioned in the ring 31 between each adjacent anchor hole 3113 and are configured to improve the rigidity of the ring 31. The additional spacers 315 may be spacers in the shape of plates perpendicular to the planes tangent to the anchor disc 311 and the fixing disc 312, or they may be spacers of different shapes, but they are always positioned in the anchor disc 311 and the fixing disc 312 so as not to block the anchor holes 3113, clamp holes 3123, or fixing holes 3124.

[0067] Method for connecting the tower to the foundation The ring 31 is preferably manufactured before the assembly of the wind turbine E. For example, in the case of an offshore wind turbine E, the ring 31 is supplied either directly as a single component or as a plurality of joint corners 36, each of which is an integral structure, as shown in Figure 2b, and is joined when the tower 2 is connected to the foundation 1.

[0068] The method for connecting Tower 2 to Foundation 1 may involve multiple steps using the various elements that constitute the wind turbine E, as shown in Figure 6 and described above. This method is shown in Figures 5a to 5j in the radial cross-section of the wind turbine E, in relation to the diagram shown in Figure 4.

[0069] The method first includes a step (step E1) of providing a foundation 1 with a central column 11 cast using formwork 6, leaving a duct 14 for arranging prestress cables 321. The duct 14 is obtained by placing metal trumpets 15 in formwork 6 before concrete is cast in formwork 6. The trumpets 15 allow the duct 14 to remain without concrete, thereby allowing for the subsequent arrangement of prestress cables 321. Each trumpet 15 is an extension of the duct 14. The trumpets 15 allow for the absorption of installation obstacles between the duct 14 and the ring 31. Figure 5a is a radial cross-sectional view of a portion of the central column 11 cast in a hollow cylindrical shape.

[0070] Once the foundation 1 is poured, the formwork 6 is removed, and as shown in Figure 5b, the leveling device 7 can be positioned and adjusted at the upper end 112 of the central column 11 of the foundation 1 (step E2).

[0071] As shown in Figure 5c, circular seals 8 are positioned at the upper end 112 of the central column 11 and around each metal trumpet 15, i.e., around each duct 14 provided for arranging the prestressed cables 321 (step E3). The circular seals 8 around each duct 14 protect the duct 14 from unwanted injection, as described later.

[0072] Subsequently, as shown in Figure 5d, the ring 31 is positioned on the central column 11 of the foundation 1, i.e., on the foundation 1 (step E4). In this way, the anchor disc 311 of the ring 31 is placed on the leveling device 7 that has been previously positioned on the foundation 1. The position of the ring 31 is adjusted by the leveling device 7. The ring 31 is positioned so that each anchor hole 3113 of the anchor disc 311 of the ring 31 faces the respective duct 14 provided for arranging the prestressed cables 321.

[0073] Once the ring 31 is positioned and its position is adjusted, a layer of anchor grout 9 is injected between the concrete foundation 1 and the ring 31, that is, between the upper end 112 of the central column 11 of the foundation 1 and the anchor disc 311 of the ring 31 (step E5). As shown in Figure 5e, the layer of anchor grout 9 improves the positioning of the ring 31 in the foundation 1. Due to the presence of circular seals 8 around each of these ducts 14, the anchor grout 9 does not enter the ducts 14 provided for arranging the prestressed cables 321.

[0074] Next, as shown in Figure 5f, the prestressed cables or stranded cables are inserted into each duct 14 provided in the foundation 1 (step E6). Then, the anchor heads 322 and anchor plates 323 of each anchoring means 32 are positioned on the respective prestressed cables 321 (step E7), and as shown in Figure 5g, the prestressed cables 321 are clamped in each anchor hole 3113, thereby fixing the ring 31 to the foundation 1.

[0075] Optionally, to simplify the method, the anchor plate 323 may be omitted. The anchor head 322 is then placed directly on the anchor disk 311 to secure the ring 31 to the base 1.

[0076] As shown in Figure 5h, the clamping tool 5 is then inserted into each clamping hole 3123 and the ring 31 is clamped to the foundation 1 by tensioning the prestress cable 321 at each anchor head 322 (step E8). The clamping tool 5 may be a tensioning jack.

[0077] Once the ring 31 is fixed to the foundation 1 by each anchoring means 32, cement grout 10 is injected into each duct 14 around the pre-inserted prestressed cables 321, as shown in Figure 5i (step E9). The cement grout 10 is injected through each clamp hole 3123 and anchor hole 3113. Furthermore, cement grout 10 is also injected around each anchor head 322. The injection provides protection for the prestressed cables 321, causing them to adhere to the concrete, and its purpose is to improve the fixation of the ring 31 in the foundation 1.

[0078] Finally, as shown in Figure 5j, the tower 2 of the wind turbine E is positioned on the ring 31 (step E10). That is, the flanges 211 of the legs 21 of the tower 2 of the wind turbine E are positioned on the fixing discs 312 of the ring 31. As shown in Figure 4, the tower 2 is positioned such that the fixing holes 2113 and 2114 of the flange 211 are positioned opposite the respective fixing holes 3124a and 3124b of the fixing disc 312. Then, the fixing means 33 are inserted into the fixing holes 2113 and 2114 of the flange 211, and the tower 2 is fixed to the ring 31.

[0079] Therefore, the tower 2 of the wind turbine E is fixed to the ring 31 via fixing means 33, and the ring 31 itself is directly anchored to the foundation 1 by anchoring means 32. Thus, the tower 2 is connected to the foundation 1 via a single intermediate member, the ring 31, and the respective attachments of the tower 2 and the foundation 1 to the ring 31 are independent of each other.

Claims

1. A metal ring (31) for connecting a T-flange (211) at the leg portion (21) of a metal wind turbine tower (2) to a concrete foundation (1), wherein the ring (31) has a generally annular shape centered on the axis (X) of the tower (2), - An anchor disc (311) having a plurality of anchor holes (3113), wherein each anchor hole (3113) is adapted to allow the passage of a prestress cable (321) in order to anchor the anchor disc (311) in the concrete foundation (1), - A fixed disc (312) positioned apart from the anchor disc (311) by first spacers (313, 314) and including a plurality of clamp holes (3123), each of which is positioned opposite to each anchor hole (3113) of the anchor disc (311), allowing a clamping tool (5) to engage with the clamp holes (3123) to apply tension to the prestress cable (321) passing through the anchor hole (3113) opposite to the clamp hole (3123); The anchor disk (311) and the fixed disk (312) are connected to each other by the first generally annular metal spacers (313, 314); The anchor disk (311), the fixed disk (312), and the spacers (313, 314) are arranged around the axis (X) and form a single member; The fixing disk (312) further includes through fixing holes (3124a, 3124b) adapted to allow the tower (2) to be fixed to the fixing disk (312), A metal ring (31).

2. The ring (31) according to claim 1, wherein the anchor disk (311) and the fixed disk (312) are connected to each other by a second generally annular metal spacer (313, 314), the second generally annular metal spacer (313, 314) is positioned around the axis (X) and together with the anchor disk (311), the fixed disk (312), and the first spacer (313, 314) forms a single member.

3. The first spacer and the second spacer (313, 314) are hollow cylindrical in shape, and one of the first spacer and the second spacer (313, 314) forms a first hollow cylinder and is positioned radially inward relative to the anchor hole (3113) and the clamp hole (3123), and the other forms a second hollow cylinder and is positioned radially outward relative to the anchor hole (3113) and the clamp hole (3123). The ring (31) according to claim 2, wherein the first spacer and the second spacer (313, 314) are welded to the anchor disk (311) and the fixed disk (312).

4. The ring (31) according to any one of claims 1 to 3, wherein the anchor disc (311) and the fixing disc (312) are connected to each other by a plurality of additional metal spacers (315), each adjacent anchor hole (3113) is separated from each other by the additional spacers (315), and the additional spacers (315) are welded in the anchor disc (311) and the fixing disc (312).

5. The ring (31) according to any one of claims 1 to 4, wherein the fixing disk (312) includes a plurality of groups (3125) of fixing holes (3124a, 3124b), each group (3125) being located near and surrounding each of the clamp holes (3123), with two intrados fixing holes (3124a) located radially inward from the clamp holes (3123) and two extrados fixing holes (3124b) located radially outward from the clamp holes (3123).

6. The ring (31) according to any one of claims 1 to 5, comprising a plurality of joining ring corners (36) around the aforementioned axis (X).

7. A connecting device (3) comprising a ring (31) according to one of claims 1 to 6, and fixing means (32) for fixing the ring (31) to a concrete foundation (1), wherein the fixing means (32) each includes a plurality of prestress cables (321) intended to be fixed to the concrete foundation (1), and an anchor head (322) for fixing the ring (31) to the prestress cables (321).

8. A wind turbine (E) comprising a rotor (42), a generator (41), a tower (2), a foundation (1), and a connecting device (3) as described in claim 7.

9. A method for connecting a metal wind turbine tower (2) to a concrete foundation (1) using the connecting device (3) described in claim 7, - A step (E1) of pouring the concrete foundation (1), wherein during pouring, a duct (14) is provided by a metal trumpet (15) for positioning the prestress cable (321), - A step (E2) of adjusting a plurality of leveling devices (7) at the upper end (112) of the concrete foundation (1), - Step (E3) of placing the respective circular seals (8) around each duct (14) at the upper end (112) of the concrete foundation (1), - Step (E4) of positioning the ring (31) in the leveling device (7) such that the anchor disc (311) faces the concrete foundation (1) and each anchor hole (3113) is coaxial with each of the respective ducts (14), - Step (E5) of injecting a layer of anchor grout (9) between the concrete foundation (1) and the ring (31), - Step (E6) of inserting the prestressed cable (321) into the duct (14), - Step (E7) of arranging an anchor plate (323) and the anchor head (322) in each of the anchor holes (3113) and clamping the prestressed cable (321) in each anchor hole (3113), - Step (E8) of fixing the ring (31) to the concrete foundation (1) by the clamping tool (5) inserted into each of the clamping holes (3123), and tensioning the prestress cable (321) at the anchor head (322), - Step (E9) of injecting cement-based grout (10) into the duct (14) around the prestress cable (321) and around the anchor head (322), - Step (E10) of fixing the tower (2) to the ring (31) by clamping the fixing means (33) in each fixing hole (3124a, 3124b) of the fixing disk (312), A method that includes this.

10. The method according to claim 9, wherein the step (E8) of fixing the ring (31) to the concrete foundation (1) is carried out by a tension jack (5).

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