Floating support structure with multiple center ports for an offsel wind

Abstract

The invention relates to a floating support structure (2-1) for an offshore wind turbine, comprising: a lower connector (4) centered on the axis (X-X) of the mast (9) of the wind turbine, said lower connector (4) comprising at least three lower receiving grooves (10) uniformly distributed around the axis of the mast of the wind turbine; an upper connector (6) centered on the axis of the mast of the wind generator, the upper part of which comprises means (14) for receiving the mast of the wind generator and the lower part of which comprises at least three upper receiving grooves (12) uniformly distributed around the axis of the mast of the wind generator; and at least three identical tubular central posts (8), the lower end of which is fitted in one receiving groove of the lower connector and the opposite upper end of which is fitted in one receiving groove of the upper connector (so as to form a floating support tower adapted to the vertical extension of the mast of the wind turbine). The invention further relates to an assembling method of the structure.

Description

Technical Field

[0001] The present invention relates to the general field of offshore wind turbines implanted off-shore, and in particular to a floating support structure for a floating offshore wind turbine.

[0002] The invention also relates to a method for installing an offshore wind turbine, wherein the offshore wind turbine is equipped with such a supporting structure. Background Art

[0003] The purpose of offshore wind turbines is to generate electricity from wind energy with the help of turbines and generators. There are two main types of offshore wind turbines: one is a fixed wind turbine, which is implanted in the seabed (the lowest depth is usually less than 50 meters); the other is a floating wind turbine, which has the advantage of being built on land and applied in areas where the seabed depth is usually more than 50 meters.

[0004] The floating wind turbine, which is the subject of the present invention, comprises a turbine, generally consisting of an electric motor having a plurality of rotating blades with a horizontal axis and a generator connected to the motor, the motor and the generator being fixed to the upper end of a vertical mast (or tower). The lower end of the mast itself is mounted on a floating support structure.

[0005] There are four main types of floating support structures used for offshore wind turbines: semi-submersible floaters, submerged floaters with tensioned cables (or "TLP" platforms, meaning "tension leg platforms"), "SPAR" type floaters (standing for "single point mooring power storage device"), "barge" type semi-submersible floaters and floaters equipped with pendulum-type counterweights.

[0006] Semi-submersible floats are the most widely used type of floats. They consist of a base made of steel or concrete, which is generally in the form of a tripod with three (or four) cylindrical pillars connected together by a metal structure. The stability of this structure is ensured by a ballast system that allows part of the base to be immersed in water. This structure is characterized by a large volume and a shallow draft. Reference publication WO 2019 / 106283 describes a semi-submersible float structure and a method for installing a wind turbine equipped with such a float structure.

[0007] A TLP is a floating object that is mostly submerged in water and is connected to the seabed by cables that prevent it from rising by applying a downward force.

[0008] The "SPAR" type float is characterized by its cylindrical shape that fits into the extension of the wind turbine mast. Its stability is provided by heavy ballast that lowers the center of gravity of the device and is equipped with a catenary anchor for hooking the wind turbine to the seabed. Reference may be made to publications WO 2005 / 021961, WO 2006 / 121337 and WO 2006 / 132539, which describe examples of "SPAR" platforms and their anchoring and offshore installation processes.

[0009] Finally, the “barge” type semi-submersible floaters adopt a more compact base form, similar to a rectangular barge with a hole in the center, which is mainly composed of concrete or steel.

[0010] Most floating support structures are not designed to be industrialized on a large scale. In fact, these floating structures are generally composed of a large number of parts that need to be assembled, which requires time and ground space. Summary of the invention

[0011] The object of the present invention is to propose a floating support structure ("SPAR" type, semi-submersible or "TLP" type) for offshore wind turbines that simplifies and speeds up assembly and minimizes the land space required.

[0012] According to the present invention, a floating support structure having multiple central columns for an offshore wind turbine is provided to achieve the above-mentioned object, the structure comprising: - at least two identical and independent tubular central columns assembled together around the axis of the mast of the wind turbine to form a floating support tower adapted to the vertical extension of the mast of the wind turbine; - a lower connector, centered on the axis of the mast of the wind turbine, intended to ensure that the forces of the central column are retained and carried at their respective lower ends; and - an upper connector, centered on the axis of the mast of the wind turbine, comprising, at the upper part, a receiving device for the mast of the wind turbine, and, at the lower part, at least two upper receiving grooves for receiving the upper end of the central column.

[0013] The salient feature of the present invention is that it adopts a modular approach to constructing a floating support structure. Specifically, the present invention uses a plurality of identical and independent central columns, assembled into a floating support tower with the help of upper connectors and lower connectors. The number of central columns can be 2, 3, 4, 5, 6, etc., so that the design of the floating support structure can be varied according to the conditions of the installation location of the structure.

[0014] The fact that the central columns are all identical greatly simplifies the assembly of the floating support structure. In fact, these central columns as well as the upper and lower connectors can be prefabricated one after another using the same model and quickly assembled on site. This simplifies the assembly process and saves time.

[0015] The floating support tower can be without crosspieces, thus forming a SPAR type floating structure.

[0016] Alternatively, each central column is connected to at least one tubular crosspiece, the end of the tubular crosspiece opposite to the central column forming a floating node, and the floating node is radially spaced from the floating support tower to form a semi-submersible floater.

[0017] In one variant, each central column is connected to at least one radial cross piece in the area where its lower end is located on the one hand, and is connected to at least one oblique cross piece above its lower end on the other hand, and the radial cross pieces and the oblique cross pieces are connected together in the area where the floating node is located to form a triangular floating unit assembly.

[0018] In another variant, each central column is connected to at least one first radial cross piece in the area where its lower end is located, and is connected to at least one second radial cross piece above its lower end, and the multiple radial cross pieces are connected together in the area where the floating node is located to form a rectangular floating unit assembly.

[0019] Preferably, each floating unit assembly comprises at least one floating module arranged in the area where its floating node is located.

[0020] Each floating module may include a central pole extending in a direction parallel to the axis of the mast of the wind turbine, and at least one steel ring and / or at least one non-metallic material ring is mounted on the central pole.

[0021] The axis of the mast of the wind turbine may coincide with the center of symmetry of the floating object. Alternatively, the axis of the mast may be offset relative to the center of symmetry of the floating object.

[0022] Preferably, the floating nodes of the floating unit assembly are connected to each other by at least one cable, and the floating nodes include a tensioning device for the cable.

[0023] The structure may further comprise at least one buoyancy element disposed about the cable.

[0024] Preferably, each floating unit assembly comprises a ballast network located inside at least one crosspiece and inside at least one central column.

[0025] The floating support tower and / or the at least one radial crosspiece may comprise at least one central floating unit.

[0026] In one variation, the lower connector is a separate component of the center column, and the lower connector includes at least two lower receiving grooves, each lower receiving groove receiving a lower end of the center column.

[0027] In another variation, the lower connector is a cable clamp for clamping each lower end of the center column.

[0028] Another object of the present invention is to provide an assembly method for the floating support structure as described above, comprising the following steps: assembling the lower end of each center column to the lower connector in a dry assembly manner, and then assembling the upper connector to the upper end of each center column in a dry assembly manner.

[0029] Another object of the present invention is to provide an assembly process of the floating support structure as described above, comprising the following consecutive steps: - a step of assembling the floating unit assemblies on the lower connectors, ensuring proper lateral positioning of the floating unit assemblies by lifting and pivoting each unit assembly so that the floating nodes rest on supports previously arranged on the ground; - a step of assembling said upper connector at said upper end of said central column of each floating unit assembly; and - A step of connecting the central column of the floating unit assembly to the upper connector and the lower connector by welding, bonding or mechanical assembly.

[0030] The assembling step may be performed on a submersible platform that enables the floating support structure to be launched in a calm area not affected by surges.

[0031] In this case, the submersible platform is preferably equipped with a lifting gantry for assembling the mast of the wind turbine to the upper part of the upper connector of the floating support structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] [ Figure 1 ] Figure 1 is a perspective view of a semi-submersible floating support structure having four floating unit assemblies according to a first embodiment of the present invention.

[0033] [ Figure 2 ] Figure 2 yes Figure 1 A side view of the floating support structure is shown.

[0034] [ Figure 3 ] Figure 3 yes Figure 1 and Figure 2 Exploded view of the floating support structure shown.

[0035] [ Figure 4A ] Figure 4A is a perspective view of a SPAR type floating support structure according to a second embodiment of the present invention.

[0036] [ Figure 4B ] Figure 4B is an exploded view of a variant of a SPAR type floating support structure according to the second embodiment of the present invention.

[0037] [ Figure 5 ] Figure 5 is a perspective view of a semi-submersible floating support structure having three floating unit assemblies according to a third embodiment of the present invention.

[0038] [ Figure 6 ] Figure 6 is a perspective view of a semi-submersible floating support structure having five floating unit assemblies according to a fourth embodiment of the present invention.

[0039] [ Figure 7 ] Figure 7 is a perspective view of a semi-submersible floating support structure having six floating unit assemblies according to a fifth embodiment of the present invention.

[0040] [ Figure 8 ] Figure 8 is a perspective view of a floating support structure according to a modified embodiment of the first embodiment of the present invention.

[0041] [ Fig. 9 ] Fig. 9 is a perspective view of a floating support structure according to another variant embodiment of the first embodiment of the present invention.

[0042] [ Fig.10 ]to[ Fig.17 ] Figures 10 to 17 According to the present invention, Figure 1 Schematic views of different steps of the assembly process of a floating support structure.

[0043] [ Fig.18 ] Fig.18 Given the installation Figure 1 An illustrative view of an offshore wind turbine undergoing maintenance on a floating support structure.

[0044] [ Fig.19 ] Fig.19 is a perspective view of a floating support structure according to a further variant embodiment of the first embodiment of the present invention, wherein there is a central floating unit between the central columns.

[0045] [ Fig. 20 ] Fig. 20is a perspective view of a modified embodiment of the floating support structure according to the third embodiment of the present invention.

[0046] [ Fig.21 ] Fig.21 1 is a perspective view of a semi-submersible floating support structure according to a sixth embodiment of the present invention, wherein the semi-submersible floating support structure is arranged in a staggered manner with two floating unit assemblies.

[0047] [ Fig.22A ] Fig.22A This is a modified embodiment of the floating support structure according to the third embodiment.

[0048] [ Fig. 22B ] Fig. 22B Another modified embodiment of the floating support structure according to the third embodiment is shown.

[0049] [ Fig.23 ] Fig.23 An embodiment of a ballast network within a floating support structure according to the invention is shown. DETAILED DESCRIPTION

[0050] Figures 1 to 3 A semi-submersible floating support structure 2-1 according to a first embodiment of the invention is shown, which is intended to receive a mast (not shown) of an offshore wind turbine.

[0051] According to the present invention, the floating support structure 2-1 includes a lower connector 4, an upper connector 6 and a plurality of (i.e., at least two, Figures 1 to 3 The components between the first embodiment (up to four) tubular central columns 8, which are identical and independent of each other, form a tower adapted to the vertical extension of the mast 9 of the wind turbine.

[0052] The diameter of the central column 8 is generally between 2 and 4 meters. They may or may not be reinforced on the inside. They are usually made by different assembly techniques and can be easily produced without large investments.

[0053] like Figure 3 As shown, in this embodiment, the lower connector 4 is an independent component of the central column, which is centered on the vertical axis XX of the mast of the wind turbine, and includes at least two (four in this embodiment) lower receiving grooves 10, which are evenly distributed around the vertical axis XX and open upward, and each lower receiving groove 10 is intended to receive the lower end of the central column 8 in a shape-complementary nesting manner.

[0054] Similarly, the upper connector 6 is an independent component of the central column, which is centered on the vertical axis XX of the mast 9 of the wind turbine and includes at least two (four in the present embodiment) upper receiving grooves 12 at the lower part. These upper receiving grooves 12 are evenly distributed around the vertical axis XX, open toward the bottom, and each upper receiving groove is intended to receive the upper end of the central column 8 by a shape-complementary nesting manner.

[0055] The upper part of the upper connector 6 also comprises receiving means for the mast 9 of the wind turbine. Typically, these receiving means are in the form of rings 14 in which the lower end of the mast of the wind turbine is mounted before being fixed (for example by welding).

[0056] Of course, other receiving devices can also be envisaged for the mast of the wind turbine.Similarly, it can be envisaged that the upper connector forms a same integral part with at least a part of the mast of the wind turbine.

[0057] As for the central columns 8, they are all identical and independent of each other, and each central column is in the form of a cylinder, which extends vertically, and its lower end is nested and assembled in a receiving groove 10 of the lower connector 4, and its upper end is nested and assembled in a receiving groove 12 of the upper connector 6.

[0058] Preferably, if Figure 4B As shown, each receiving groove 10 of the lower connector and / or the receiving groove 12 of the upper connector has a centering guide 16, which is intended to make the assembly of the corresponding ends of the central column easier.

[0059] For example, in Figure 4B In the embodiment of the present invention, these centering guides 16 are shown as two plates 16a and 16b arranged in a cross-shaped manner, and their end portions are formed into tips by beveling. Of course, the centering guides can also be in other forms.

[0060] After being placed into the receiving grooves 10 and 12 of the upper and lower connectors, the center column 8 is fixed to the connector by welding, bonding or mechanical assembly.

[0061] Figures 1 to 3 The first embodiment of the invention shown relates to a "semi-submersible" floating structure having four floating unit assemblies.

[0062] By "floating unit assembly" is meant at least one radial tubular crosspiece and at least one diagonal tubular crosspiece for each central column, which are connected on the one hand to the central column and on the other hand to a floating node which is radially spaced from the floating support tower.

[0063] In the various embodiments described below ( Figure 4A , 4B, 22A and 22B), the floating unit assembly is triangular.

[0064] More specifically, in these embodiments, for each central column 8, a radial tubular crosspiece 20 is connected to the lower end of the central column by forming an angle between 75° and 90° with the lower end of the central column, and an oblique tubular crosspiece 22 is connected to the column above the lower end of the central column on the one hand, and is connected to the free end of the radial crosspiece by forming a floating node 24 with the radial crosspiece on the other hand, thereby forming a floating unit assembly 18 having a triangular shape, wherein the floating node 24 is radially spaced apart from the vertical axis XX.

[0065] Preferably, these triangular floating unit assemblies 18 are identical to each other, which makes them easier to produce on the one hand and to assemble them to the upper and lower connectors on the other hand.

[0066] In the first embodiment, the floating support structure 2 - 1 has four triangular floating unit assemblies 18 of the same shape, which are evenly spaced from each other (ie, all spaced 90° apart).

[0067] Of course, depending on the number and arrangement of the radial and diagonal rungs, the floating unit assemblies may have shapes other than triangular. Likewise, they may not necessarily be identical to one another.

[0068] Furthermore, each floating unit assembly 18 comprises a floating module 26 located in the region of its floating node 24, ie at the free ends of the radial crosspieces 20 and the diagonal crosspieces 22 (opposite to the vertical axis XX of the mast).

[0069] Each floating module 26 comprises a central pole 28 extending parallel to the vertical axis XX of the mast, on which is mounted at least one steel ring 30 constituting a ballast tank and / or at least one ring 32 made of non-metallic material.

[0070] Therefore, in Figure 1 and Figure 2 In the embodiment, each floating module 26 includes a steel ring 30, three non-metallic material rings 32 are arranged above the steel ring 30, and two other non-metallic material rings 32 are arranged below the steel ring 30.

[0071] The advantage of this is that the non-metallic material rings 32 are all standardized and identical to each other (in terms of size and material), which helps to adjust the number of non-metallic material rings 32 at each floating node 24 according to the installation conditions of the wind turbine.

[0072] These non-metallic rings 32 are made of non-metallic materials, which can be solid materials or synthetic foam materials to play a buoyancy role. The non-metallic material can be a thermosetting material, a thermoplastic material or an elastomer. These non-metallic rings are fixed to the center rod 28 by any means (such as a spring-shaped retaining ring).

[0073] In addition, the steel ring 30 constituting the ballast tank is connected to the ballast pipe network (see Fig.23 ), the pipe network is located inside at least one of the crosspieces 20, 22 and the central column, and ends in the area where the control area (not shown in the figure) located above the upper connector 6 is located.

[0074] The floating nodes 24 of the floating unit assemblies 18 are connected to each other by at least one cable 36, at least some of which are equipped with a device for tightening the cable. The cables 36 are thus prestressed, which can effectively reduce the overall weight of the floating support structure and shorten the assembly time of the latter.

[0075] like Figure 1 As shown, in relation to the first embodiment, a plurality of metal cables 36 may be connected in pairs to the floating nodes of the floating unit assembly 18 .

[0076] In this case, the tensioning of the cable 36 can be ensured by a screw-nut system or hydraulic jacks (working in pulling) to pull one end of the cable towards one of the floating nodes, while the other end of the cable is connected to the adjacent floating node. In this configuration, the number of tensioning devices of the cable is the same as the number of floating unit assemblies 18. In the case of hydraulic jacks, these tensioning devices are removable.

[0077] In a variant with multiple cables (not shown), only one cable tensioning device may be provided. When tightening a cable, the other cables are also tightened, because in this variant, the floating unit assembly has the possibility of rotating about the vertical axis XX in the area where it is anchored to the upper and lower connectors.

[0078] In a variant embodiment not shown, this can be the same and only cable or metal chain connecting all the floating nodes of the floating unit assembly. In this variant, a single cable passes through the grooves of each floating node, which are equipped with stops (cable clamps) for fixing the position of the cable after the tension is generated. In this way, the trajectory of the cable corresponds to the circumference of the floating support structure formed by the floating unit assembly 18. The tension of the cable or chain is generated by means such as jacks or screw-nut systems fixed at both ends of the cable (or chain).

[0079] Finally, a possible alternative to cables is to use horizontal steel spacers to connect the floating nodes of the floating unit assembly together. Quick mechanical connectors then secure the connection between the spacers and the floating nodes, minimizing installation time.

[0080] Figure 4A and Figure 4B Two variants 2 - 2 and 2 - 2 ′ of the floating support structure according to the second embodiment of the present invention are shown in perspective view and exploded view respectively.

[0081] The floating support structure 2-2, 2-2' according to the second embodiment of the invention forms a "SPAR" type float (ie "Single Point Mooring Reservoir"), ie a cylindrical float nested in an extension of a wind turbine mast.

[0082] More precisely, according to Figure 4A The floating support structure 2-2 of the variant comprises four tubular central columns 8 which are identical and independent of each other so as to form a tower adapted to the vertical extension of the mast of a wind turbine.

[0083] Similarly, according to Figure 4B The floating support structure 2 - 2 ′ of this variant comprises three tubular central columns 8 , which are identical to one another to form a tower.

[0084] Furthermore, in contrast to the first embodiment, the central columns 8 of the towers constituting the two floating support structures 2 - 2 , 2 - 2 ′ are not provided with crosspieces (either radially or obliquely).

[0085] Figure 5 is a perspective view of a floating support structure 2 - 3 according to a third embodiment of the present invention.

[0086] In this embodiment, the floating support structure 2-3 forms a semi-submersible floater having three floating unit assemblies 18 spaced apart from each other at the same angle of 120. In this structure, the cables 36 form a triangle.

[0087] Other features of the floating support structure are similar to those of the structure described in the first embodiment.

[0088] Figure 6 is a perspective view of a floating support structure 2 - 4 according to a fourth embodiment of the present invention.

[0089] In this embodiment, the floating support structures 2-4 form a semi-submersible float having five floating unit assemblies 18 spaced apart from each other at the same angle of 72. In this structure, the cables 36 form a pentagon.

[0090] Other features of the floating support structure are similar to those of the structure described in the first embodiment.

[0091] Figure 7 is a perspective view of a floating support structure 2 - 5 according to a fifth embodiment of the present invention.

[0092] In this embodiment, the floating support structure 2-5 forms a semi-submersible float having six floating unit assemblies 18 spaced apart from each other at the same 60° angle. In this structure, the cables 36 form a hexagon.

[0093] Other features of the floating support structure are similar to those of the structure described in the first embodiment.

[0094] Figure 8 is a perspective view of a floating support structure 2-1' according to a variant embodiment of the first embodiment of the present invention, ie, a floating support structure forming a semi-submersible float, having four floating unit assemblies 18 spaced apart from each other at the same 90° angle.

[0095] The special feature of this variant embodiment is that floating elements 38 are installed around each cable 36. For example, these floating elements 38 are in the form of foam cylinders that are sheathed outside the cables.

[0096] These floating elements 38 complement each other with the floating modules 26 arranged in the area where the floating nodes of the floating unit assembly 18 are located.

[0097] Other features of the floating support structure are similar to those of the structure described in the first embodiment.

[0098] Fig. 9 is a perspective view of a floating support structure 2-1" according to another variant embodiment of the first embodiment of the present invention, i.e., a floating support structure forming a semi-submersible float, having four floating unit assemblies 18 spaced apart from each other at the same 90° angle.

[0099] The special feature of this variant embodiment is that a floating unit 40 is arranged around the radial crosspiece 20 of each floating unit assembly 18. For example, these floating units 40 are in the form of foam cylinders and are sheathed outside the radial crosspiece.

[100] Here, these floating units 40 can replace the floating modules arranged in the area where the floating nodes 24 of the floating unit assembly 18 are located.

[101] Other features of the floating support structure are similar to those of the structure described in the first embodiment.

[102] Figures 10 to 17An assembly and installation example of a floating support structure according to the present invention, in particular, an assembly and installation example of a floating support structure 2 - 5 according to the fifth embodiment of the present invention is shown.

[103] Of course, the assembly process applicable to other embodiments of the present invention can obviously refer to the assembly process described below.

[104] Assembly can be carried out quayside or on an offshore assembly platform (catamaran type), which can be submersible. The use of a submersible catamaran offers greater autonomy, independence from the installation site and, most importantly, the availability of lifting equipment at the installation site.

[105] The upper and lower connectors and floating unit components can be mass-produced before assembly begins.

[106] In the first step, a cylindrical counterweight 42 is placed on the ground at the assembly site. The counterweight is intended to be fixed to the floating node 24 of the floating unit assembly 18 by a rope 50 to ensure the gravity anchoring of the floating support structure (see Fig.18 Positioning shown).

[107] Fig.10 In the embodiment shown, the counterweight 42 presents a central recess 44 intended for connection to the lower connector of the floating support structure.

[108] Fig.11 In the subsequent step shown, the lower connector 4 of the floating support structure is moved (for example by a crane or a lifting gantry) to be placed in the groove 44 of the counterweight 40. In the absence of a groove, the lower connector is placed directly on the counterweight.

[109] In the next step ( Fig.12 ), positioning supports 46 are advantageously placed on the assembly site around counterweight 42 at the precise locations where the floating modules of the floating unit assembly need to be placed.

[110] These positioning supports 46 ensure quick and accurate positioning of the floating unit assembly and perfect adjustment of the verticality of the central column when placing the upper connector. Of course, they can be reused.

[111] Fig.13 As shown, the floating unit assemblies 18 are sequentially assembled on the lower connector 4. Specifically, each floating unit assembly 18 is lifted (by a crane or a lifting gantry), and the lower end of its central column 8 is vertically introduced into a receiving groove 10 of the lower connector. The floating unit assembly also rotates around its central column so that its floating module 26 is located on one of the positioning supports 46.

[112] Fig.14 The assembly of the second floating unit assembly 18 to the lower connector 4 is shown.

[113] Fig.15 The structure formed after all the floating unit components 18 are assembled to the lower connector 4 is shown.

[114] After all the floating unit components 18 are assembled and subsequently fixed to the lower connector 4 (by welding, gluing or mechanical assembly), Fig.16 The following steps shown involve fitting the upper connector 6 (by crane or fitting gantry) to the upper end of the central column and then securing these parts together (by welding, gluing or mechanical fitting).

[115] Subsequently, the control platform 48 can be installed near the upper end of the upper connector 6.

[116] In the final assembly step of the floating support structure 2-5 (ref. Fig.17 ), the cables 36 are fixed to the respective floating nodes 24 of the floating unit assembly 18 and then tightened. Subsequently, the mast and turbine of the wind turbine are installed by a crane or a lifting gantry.

[117] Fig.18 As shown, the offshore wind turbine installed on the floating support structure of the present invention can be maintained (here, the structure 2-1 has four Figure 1 The floating unit assembly shown), in particular, an assembly that can replace the turbine 52 or the blades 54.

[118] To this end, the oblique crosspieces 22 of at least some of the floating unit assemblies 18 of the floating support structure 2-1 are equipped with shafts 56 (see also Figure 1 ) in order to install a temporary platform 58 for installing the telescopic structure 60.

[119] Obviously, the shaft 56 may also adopt other maintenance structures in connection with the optional configuration of the climbing crane.

[120] Regardless of the specific embodiment of the present invention, when assembling the floating support structure, it is obvious that at least one central floating unit 62 can be inserted between the central columns 8 constituting the tower (see Fig.19 The floating support structure 2-1 having four floating unit assemblies 18 and Fig.21 The central floating unit 62 can enhance the buoyancy of the floating support structure.

[121] Thus, Fig.19 In the example shown, the central floating unit 62 (for example a foam cylinder) is inserted vertically between the central columns along the axis XX, prior to the step of placing the upper connector on the upper end of the central columns.

[122] Another method not shown in the drawings is that this central floating unit can be pre-installed on the first assembled central column when the floating support structure is installed.

[123] Fig. 20 2 is a perspective view of a modified embodiment of the floating support structure 2 - 3 ′ according to the third embodiment of the present invention.

[124] This variant embodiment is Figure 5 The difference of the embodiment shown is that the lower connector of the structure does not include a lower receiving groove for receiving the lower end of the column. Instead, a simple cable clamp 4' is used to clamp the lower ends of the central columns.

[125] In this variant embodiment, in order to facilitate the assembly of the central column of the floating support structure 2-3', a temporary installation can be made on the ground. Figure 5 A lower connector of the type described.

[126] All embodiments of the floating support structure according to the invention described so far relate to a structure in which the axis XX of the wind turbine mast coincides with the centre of symmetry of the floating structure (the floating support tower being located at the centre of symmetry of the structure).

[127] By contrast, Fig.21 is a perspective view of a semi-submersible floating support structure according to a sixth embodiment of the present invention, the floating support structure being offset.

[128] In this sixth embodiment, the floating support structure 2-6 comprises only two floating unit assemblies 18, which together form an angle of 180°. In addition, the axis X'-X' of the mast 9 of the wind turbine is offset relative to the center of symmetry of the structure.

[129] In addition, in the sixth embodiment, each of the two floating unit assemblies 18 includes two floating modules 26, and the two floating modules 26 are respectively located in the area where the floating nodes 24 of the corresponding floating unit assembly are located. Of course, the situation that each floating unit assembly has two floating modules is also applicable to the floating support structure of other embodiments.

[130] Also in the sixth embodiment, the cables connecting the respective floating nodes 24 of the two floating unit assemblies 18 are replaced by support members 36'.

[131] In addition, this sixth embodiment also provides a function of arranging a central floating unit 62 between the central columns 8 forming the tower.

[132] Fig.22A and Fig. 22B Two variant embodiments of a semi-submersible floating support structure 2-3" according to the third embodiment having three rectangular-shaped floating unit assemblies are shown.

[133] In these two variant embodiments, each floating unit assembly 18' has a rectangular shape, having a central column 8 and two radial crosspieces 20a, 20b (in particular a high radial crosspiece 20a and a low radial crosspiece 20b separated according to the axis XX of the mast 9) and an oblique crosspiece 22.

[134] In addition, Fig.22A In a variant embodiment of the present invention, the floating module 26' is in the form of a column having a polygonal cross-section (here, a hexagonal cross-section), which can be made by assembling a plurality of flat plates.

[135] Fig. 22BIn a variant embodiment, the floating module 26" is in the form of a cylindrical column.

[136] Fig.23 An embodiment of a ballast pipe network within a floating support structure according to the present invention is shown (partially shown in the figure), more specifically, the ballast pipe network within a triangular floating unit assembly 18.

[137] The ballast network comprises pipes 64 installed in the radial 20 and diagonal 22 crosspieces of the floating unit assembly. These pipes 64 terminate in the ballast tanks 66 in the area of ​​the floating modules and open into the same central pipe 68 housed inside the central column 8 of the floating unit assembly.

[138] In the region of its upper end, the central duct 68 is advantageously equipped with a connection system 70 that can be used in conjunction with a complementary connection system 72 in the upper connector 6 of the floating support structure. In other words, these systems 70 and 72 form a "plug and play" unit that makes the assembly and start-up of the floating support structure much easier.

Claims

1. A floating support structure (2-1 to 2-6) having a plurality of central columns for an offshore wind turbine, comprising: - at least two identical and independent tubular central columns (8) surrounding the axis (XX) of the mast (9) of the wind turbine; X'-X') are assembled together to form a floating support tower adapted to the vertical extension section of the mast of the wind turbine; - a lower connector (4) centered on the axis (XX) of the mast (9) of the wind turbine, intended to ensure that the forces of the central column are retained and carried at their respective lower ends; and - an upper connector (6) centered on the axis of the mast of the wind turbine, comprising, at the upper part, a receiving device (14) for the mast of the wind turbine, and, at the lower part, at least two upper receiving grooves (12) for receiving the upper end of the central column, - Each central column is connected to at least one tubular crosspiece (20, 22), the end of the tubular crosspiece opposite to the central column forming a floating node (24), the floating node (24) being radially spaced from the floating support tower to form a semi-submersible float.

2. The structure according to claim 1, wherein: Each central column (8) is connected to at least one radial crosspiece (20; 20a; 20b) in the region where its lower end is located, and is connected to at least one oblique crosspiece (22) above its lower end. The radial crosspieces and the oblique crosspieces are connected together in the region where the floating node (24) is located to form a triangular floating unit assembly (18).

3. The structure according to claim 1, wherein: Each central column (8) is connected to at least one first radial crosspiece (20a) in the region where its lower end is located, and is connected to at least one second radial crosspiece (20b) above its lower end. The plurality of radial crosspieces are connected together in the region where the floating node (24) is located to form a rectangular floating unit assembly (18).

4. The structure according to any one of claims 2 and 3, wherein: Each floating unit assembly (18) comprises at least one floating module (26; 26'; 26") arranged in the area where its floating node (24) is located.

5. The structure according to claim 4, wherein: Each floating module (26) comprises a central rod (28) extending in a direction parallel to the axis (XX) of the mast of the wind turbine, and at least one steel ring (30) and / or at least one non-metallic material ring (32) is mounted on the central rod (28).

6. The structure according to any one of claims 1 to 5, wherein: The axis (XX) of the mast (9) of the wind turbine coincides with the center of symmetry of the floating object.

7. The structure according to any one of claims 1 to 5, wherein: The axis (X'-X') of the mast (9) of the wind turbine is offset relative to the center of symmetry of the floating object.

8. The structure according to any one of claims 1 to 7, wherein the floating nodes (24) of the floating unit assembly are interconnected by at least one cable (36), the floating nodes comprising tensioning means for the cable.

9. The structure according to claim 8, further comprising at least one floating element (38) arranged around the cable (36).

10. The structure according to any one of claims 1 to 9, wherein: Each floating unit assembly (18) includes a ballast network located inside at least one of the crosspieces (20, 22) and inside at least one of the central columns (8).

11. The structure according to any one of claims 1 to 10, wherein: The floating support tower and / or at least one radial crosspiece comprises at least one central floating unit (62).

12. The structure according to any one of claims 1 to 11, wherein: The lower connector (4) is an independent component of the central column, and the lower connector (4) comprises at least two lower receiving grooves (12), each of which receives a lower end of the central column.

13. The structure according to any one of claims 1 to 11, wherein: The lower connector is a cable clamp (4') for clamping the respective lower ends of the central column.

14. A method for assembling a floating support structure according to any one of claims 1 to 13, comprising the following steps: The lower end of each center column (8) is assembled to the lower connector (4) in a dry assembly manner, and then the upper connector (6) is assembled to the upper end of each center column in a dry assembly manner.

15. A method for assembling a floating support structure according to any one of claims 2 to 3, comprising the following consecutive steps: - a step of assembling the floating unit assemblies (18) on the lower connector (4), said step ensuring proper lateral positioning of the floating unit assemblies (18) by lifting each unit assembly (18) and pivoting it so that the floating nodes (24) are placed on supports (46) previously arranged on the ground; - a step of assembling the upper connector (6) at the upper end of the central column (8) of each floating unit assembly (18); and - A step of connecting the central column of the floating unit assembly to the upper connector and the lower connector by welding, bonding or mechanical assembly.

16. The method according to claim 15, wherein: The assembly step is performed on a submersible platform that enables the floating support structure to be launched in a calm area not affected by surges.

17. The method according to claim 16, wherein: The submersible platform is equipped with a lifting gantry for assembling the mast of the wind turbine to the upper part of the upper connector of the floating support structure.

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