Wind turbine tower and method for joining the components thereof

Abstract

The invention relates to a wind turbine tower and to a method for joining the components thereof. The tower is formed by a nacelle (18), several tubular tower parts (1, 1'), a transition piece (2), and lattice modules (3) in the lower part, and is characterized in that the central tubular and hollow segment (4) of the transition piece (2) and at least one tubular part (1') are segmented into three identical pieces of 120º each, wherein the shells of said pieces have shear joints with threaded bolts (10) and the internal platforms (11) of said pieces are shear-connected with auxiliary plates (9') and threaded bolts (10). The method allows the segments to be joined horizontally or vertically, according to the requirements and the component in question. The joining and erection of the tower is carried out between the three columns (14) which, together with a triangle (15) that moves up and down, make up the self-erecting system.

Description

[0001] WIND TURBINE TOWER AND METHOD OF JOINING ITS COMPONENTS

[0002] DESCRIPTION

[0003] Field of invention

[0004] The present invention falls within the field of wind turbine towers, and more specifically those consisting of a transition piece arranged in a hybrid tower with the upper part formed by tubular segments and the lower part formed by lattice segments. The new transition piece and at least one of the tubular segments of the upper part of the tower are segmented and joined in situ.

[0005] Background

[0006] Onshore wind turbines face transportation limitations due to their size and weight. The largest tower diameters that can be transported are approximately 4.5 m. The heaviest towers that can be transported are approximately 80 t. The current growth in wind turbine capacity, with platforms ranging from 6 to 10 MW, demands towers 200 m high (HH). As size increases, so do the diameter and weight of the towers. To facilitate transport, they must be disassembled into segments and assembled on-site.

[0007] Wind turbine towers are fundamentally of three types: steel tubular, concrete tubular, or hybrid with steel tubular segments combined with lattice segments.

[0008] In this last configuration, there are two main groups of solutions for the transition piece that joins both segments.

[0009] On one hand, there is a group of solutions where the transition piece has an upper interface connecting the tubular tower and a lower interface connecting the tops of the lattice columns directly. This type allows for a small transition piece, but it presents challenges related to the weight of the lattice and the torsional stiffness of the tower. CN213360313 illustrates a solution of this type. On the other hand, there is a second type of pyramidal transition piece, consisting of a central tubular segment (extending the upper tubular tower into the transition) and columns connecting the top and bottom of this central tubular segment to the tops of the lattice columns.This transitional design allows for a large distance between columns at the top of the lattice, which offers significant advantages related to the lattice's weight and the tower's torsional rigidity.

[0010] -2- The same applicant of the present invention developed a pair of such transitions reflected in documents WO2021084143A1 and PCT / ES2023 / 070201.

[0011] Now, this new invention addresses the new tower sizes with transitions of this second type by segmenting some of its parts, joining them, and assembling them with the aid of an automated system described in patent EP3130796B1. Among the patents that demonstrate methods for segmenting the tubular tower of a wind turbine, the following stand out: DE3842026 shows an AEG tower comprising a number of frame segments that combine to form a complete tower structure. W00049249A1 describes a procedure for constructing a tank or silo with annular segments that have a flange on their periphery. The flanges are joined with a mechanical element: rivet, nail, or bolt, and the joint is completed with a sealing compound.The closest prior art can be considered patents W02004083633 with a tower with elongated frame segments with vertical flanges that are fixed together with bolts, said frames having horizontal flanges to allow the interconnection of frames one on top of the other and W02005075763 with a tower formed by quadrangular metal pieces with inward-facing flanges joined by fastening means. Over time, patents were added with the same solution but protecting the assembly methods WO2023274480A1, hinge the segmented tower W02016055070A1, adding tabs by welding before cutting the tower and joining it with through bolts EP3339636A1, new longitudinal seams CN107654338A and new joining pieces EP3754184A1 and CN107355350A.

[0012] Description

[0013] It is an object of the invention to assemble the hybrid tower of a wind turbine with dimensions that exceed the current transport limitations set at 4.5 m. Thus at least one section of tubular tower and the transition piece are segmented.

[0014] Another object of the invention is that the segmented pieces of the central tube of the transition piece are at least three identical pieces (one for each column of the lattice) joined longitudinally along their skins. Each of the pieces has interfaces for the inclined and horizontal columns of the transition and also contains segmented reinforcing platforms that are joined together.

[0015] Another object of the invention is that the segmented parts are transported in conventional vehicles to the assembly site. There, they are assembled by supporting the parts horizontally on fixtures designed for this purpose, either using a self-standing system to support the segmented parts or by means of a clamping system with clamps and a sliding system using ramps. The self-standing system can lift and assemble the parts simultaneously, or simply lift them and insert new parts from below.

[0016] Another object of the invention is the type of joints of the skins and the reinforcement platforms, which can be made with L-shaped flanges or with auxiliary plates that form a shear joint by fixing a mechanical element: rivet, nail or bolt.

[0017] Finally, another object of the invention is that, to reduce the weight of transport, a central cross joint can be included that divides the upper and lower parts of the central tube of the transition piece. The upper part has interfaces for inclined columns, and the lower part has interfaces for horizontal columns.

[0018] From everything described, the following advantages emerge:

[0019] - The sizes of the tower sections and the transition can exceed 4.5m in diameter, which is the current maximum in land transport due to orographic limitations with tunnels and bridges.

[0020] - The transition can be scaled up for large turbines but keeping the weights of the tower sections and the transition below 80-100 t, which is the current maximum in land transport.

[0021] - The assembly of the segmented pieces is carried out on site where the wind turbine park will be installed quickly and easily, reducing costs and with several alternatives for each situation.

[0022] Brief description of the drawings

[0023] Next, a series of drawings are briefly described that help to better understand the invention and that are expressly related to an embodiment of said invention that is presented as a non-limiting example thereof.

[0024] The first figures represent the state of the art.

[0025] Figure 1 is a longitudinally segmented transition according to a practical embodiment and a detail of the joining of its segments.

[0026] Figures 2a and 2b show the internal joints of the transition piece.

[0027] Figure 3 shows the joints made on the interior platforms.

[0028] Figure 4 shows the method of joining the segmented parts with the help of the automated system.

[0029] Figure 5 shows another method of joining the different sectors using a system for clamping and moving the segments.

[0030] Figure 6 is a longitudinally and transversely segmented transition according to a practical realization and a detail of the joining of its segments.

[0031] Detailed description

[0032] As shown in the first figures, corresponding to the prior art, the wind turbine of the invention has a tower formed by several tubular sections (1) at the top, a transition piece (2) in the middle, and a lattice tower (3) formed by several modules at the bottom. The various transition pieces (2) have evolved over time and their design has varied. They have also increased in size to support towers with larger diameters and wind turbines with higher power outputs. Due to current transport restrictions, for high-power wind turbines, at least one section of the upper tubular tower (the one closest to the transition) and the central tubular piece of the transition itself must be segmented for transport.The transition pieces (2) shown in these figures all consist of a central tubular segment (4) that extends the upper tubular tower into the transition, inclined columns (5) that connect the top of this central tubular segment to the top of the lattice columns, and horizontal columns (6) that connect the bottom of this central tubular segment to the top of the lattice columns. The number of inclined columns (5) is equal to the number of lattice columns (at least three). The number of horizontal columns (6) can be equal to the number of lattice columns (at least three) and arranged radially, or it can be greater than the number of lattice columns and connect the top of each lattice column to various points on the bottom of the central tube.

[0033] Figure 1 shows the transition (2) selected as the preferred embodiment, segmented longitudinally into three pieces. The central cylindrical piece (4) is composed of three equal curved segments (8) of 120 e each, which incorporate interfaces for the inclined (5) and horizontal (6) columns. The position of the joint line (7) is established here as equidistant from the joints of the inclined columns (5) and at the intersection of the horizontal columns (6). This line can also be positioned in another polar position depending on the design characteristics.

[0034] Similarly, the tubular section (T) of the tower that connects to the central tube of the transition (4) is formed by three equal segments of 120 eEach one and at its lower interface have L-shaped flanges (9) joined by threaded bolts (10). Thus, the first tower section (T) above the transition (2) can reach a diameter greater than 4.5 m, be transported in segments and joined on site before or during its assembly.

[0035] -5- As shown in Figure 2, the two curved segments (8 and 8') are joined inside the skins of the cylindrical piece (4) using bolted connections. These connections can be based on a shear joint of two L-shaped flanges (9) with their corresponding threaded bolt (10), as shown in Figure 2a, or on a butt joint of the two curved segments (8 and 8') using at least one auxiliary plate (9') with its corresponding threaded bolt (10) as shown in Figure 2b. This auxiliary plate (9') can be located on the inside or outside of the central tubular piece. Alternatively, there can be two plates: one inside and one outside (not shown in the figure).

[0036] Figure 3 shows the interior of the transition piece (2) and details its internal reinforcement platforms (11) arranged inside the cylindrical piece (4) in the connection areas with the corresponding inclined (5) and horizontal (6) columns. These internal platforms (11) provide transverse resistance to the tower axis in the areas where the inclined (5) and horizontal (6) columns act, and also have the secondary function of being used by operators and supporting the internal staircase and elevator.

[0037] The interior platforms (11) are divided into three pieces at 120 e(11') and its connections are shown in Figure 3a and Figure 3b. These connections can be based on a connection of two L-shaped flanges (9) joined in shear with their corresponding threaded bolt (10) (Figure 3a) or on the butt connection of the two platforms (1T) in shear by means of at least one auxiliary plate (9') with its corresponding threaded bolt (10). The auxiliary plate (9') can be on the top of the platform (11'), on the bottom, or there can be two plates (9'), one on the top and one on the bottom (Figure 3b).

[0038] Figures 4 and 5 illustrate the method of joining the tower sections. The self-erecting system consists of three columns (14) and a triangular section (15) that moves up and down between the columns. To secure the tubular tower sections (1), tie rods (16) are used, supported by the triangular section (15) and the connecting ferrule (17) located between each pair of tubular tower sections (1). Once the nacelle (18) and the first two tubular tower sections (1) have been erected, the segmented tower section (T) is inserted, followed by the segmented transition section (2).

[0039] The joining of the tubular tower segments (T) and the transition section (2) is carried out in situ. This can be done horizontally, supported by specially designed fixtures, or vertically, as shown in Figure 4. The three segments that make up the tubular section (T) are joined from inside the skins via L-shaped flanges (9) located internally and secured with threaded bolts (10). For this purpose, the three segmented sections are suspended from the triangle (15) and the previous tower sections (1), held vertically for longitudinal joining. As shown in Figure 5, in a second practical embodiment of the assembly of the sectioned segments, ramps (19) are provided inside the self-erecting system between the three columns (14). These ramps allow the segments (8 and 8'), supported by clamps (20), to be moved along them.Once the segments (8 and 8') reach the center, their skins are joined using the internal L-shaped flanges (9) and threaded bolts (10), and their platforms (11') are joined to the auxiliary plates (9') via threaded bolts (10). The assembly thus formed can be lifted to allow for the easy addition of the inclined columns (5) and horizontal columns (6) to form the transition (2). This second embodiment is also used for the assembly of the segmented tower section (T).

[0040] Once the assembly of the tower sections (1) and the transition (2) has been completed, the self-erecting system facilitates the introduction of the lattice modules (3) from the bottom, until the tower of the wind turbine of the invention is assembled.

[0041] Finally, Figure 6 shows the segmented transition (2) incorporating an additional transverse segmentation in the central cylindrical piece (4), separating it into an upper piece (4) and a lower piece (4') along a new joining line (7'), with the aim of reducing the maximum weight of the pieces during transport. The connections between the upper (4) and lower (4') pieces are based on a connection of two L-shaped flanges (9) joined by shear with their corresponding threaded bolt (10), as shown in the detail.

Claims

CLAIMS 1- A wind turbine tower crowned by a nacelle (18), the upper part of the tower being formed by tubular segments (1, 1'), the lower part by the union of several lattice modules (3), and the transition piece (2) formed by a hollow tubular central piece (4) joined to at least three inclined columns (5) joining the upper part of the hollow central piece (4) with the upper part of the lattice columns (3), and to at least three horizontal columns (6) joining the lower part of the hollow central piece (4) with the upper part of the lattice columns (3), having internal reinforcement platforms (11) in the tubular central piece (4) of the transition (2), characterized in that the hollow tubular central piece (4) and at least one section of the tubular tower (T) are longitudinally segmented into at least three segments (8), each segment incorporating joints to connect to its inclined column (5) and its horizontal column (6),The segments (8 and 8') are joined longitudinally along the skin by a shear joint line (7) with threaded bolts (10), and the pieces (11') of the internal reinforcement platforms (11) are joined together by threaded bolts (10) with shear joints. 2- Tower of a wind turbine according to claim 1, wherein the central cylindrical piece (4) is composed of three equal curved segments of 120 e each and the joining line (7) is set equidistant from the joints of the transverse columns (5) and at the intersection of the radial columns (6). 3- Tower of a wind turbine according to claims 1 and 2, wherein the joints between segments (8 and 8') are made by means of two L-shaped flanges (9) joined by shear with their corresponding threaded bolt (10). 4- Tower of a wind turbine according to claims 1 and 2, wherein the joints between segments (8 and 8') are made by means of at least one auxiliary plate (9') with its corresponding threaded bolts (10). 5- Tower of a wind turbine according to any of the preceding claims, wherein the joints between internal reinforcement platforms (11') are made by means of two L-shaped flanges (9) joined by shear with their corresponding threaded bolts (10). -8- 6- Tower of a wind turbine according to previous claims, wherein the joints between internal reinforcement platforms (11') are made by means of at least one auxiliary plate (9') with its corresponding threaded bolts (10). 7- Tower of a wind turbine according to claim 1 characterized in that the central tubular and hollow piece (4) of the transition (2): is transversely segmented into an upper piece (4) and a lower piece (4'), according to a joining line (7'), and said pieces (4 and 4') are joined by shear along the skin, by means of two L-shaped flanges (9) joined with their corresponding threaded bolts (10). 8- Method of joining the components of a wind turbine tower formed by a nacelle (18), several tower sections (1), a transition piece (2) and lattice modules (3) that are self-erected by inserting the successive components between the three columns (14) that, together with a triangle (15) that goes up and down, make up the self-erecting system, characterized by following the following steps: - Bring together the segments that make up a section of tower (1) or the segments that make up a hollow, tubular central piece (4) of the transition (2) until their walls touch and establish a joining line (7 and 7'), - the inner skins join their L-shaped flanges (9) and these flanges (9) are then pierced with threaded bolts (10), - the inner platforms (11) are joined by overlapping at least one auxiliary plate (9') that is pierced with threaded bolts (10), - When the tower component segments are fully secured, it is authorized to continue assembling new components from the bottom. 9- Joining method according to claim 8, wherein the three segmented sections hang from the triangle (15) and from the previous tower sections (1) remaining vertical to proceed to their approach and subsequent joining. 10- Joining method according to claim 8 and 9, wherein between the three columns (14) of the self-aligning system, ramps (19) are arranged along which the segments to be joined are moved in a vertical position, supported on clamps (20).

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