Active concentrated ballasting method for semi-submersible floating body of offshore wind turbine and floating body

Abstract

The invention relates to a method for active concentrated ballasting of a semi-submersible floating body for offshore wind turbines, the floating body comprising at least four columns, including one central column (4) and three external columns (6) connected to the central column by lower arms forming buoys (8), the method includes controllable and centralized deployment of ballast fluid between watertight compartments (14) formed inside each buoy (8) to enable adjustment of the float inclination. The invention further relates to a semi-submersible floating body for the offshore wind turbine. The floating body has the active concentrated ballasting function.

Description

Technical Field

[0001] This invention relates to the technical field of semi-submersible floating bodies for offshore wind turbines.

[0002] More specifically, the present invention relates to a method for ballasting such a float, and a semi-submersible float for an offshore wind turbine with active and centralized ballasting capabilities. Background Technology

[0003] Offshore wind turbines are designed to utilize wind energy to generate electricity through turbines and generators. There are two main types of offshore wind turbines: one is a stationary wind turbine, which is embedded in the seabed (usually in shallow water areas with a depth of less than 50 meters); the other is a floating wind turbine, which has the advantage of being able to be built on land and embedded in areas where the seabed depth is usually greater than 50 meters.

[0004] The floating wind turbine associated with this invention includes a turbine, which typically includes a motor with multiple blades rotating on a horizontal axis, and a generator coupled to the motor, the motor and generator being fixed to the upper end of a vertical mast (or tower). The lower end of the mast is mounted on a floating support structure (hereinafter referred to as the float).

[0005] There are several types of floating bodies for offshore wind turbines: semi-submersible floating bodies, submersible floating bodies with tension cables (or tension-leg platforms), SPAR (single-point anchored oil storage tank) type floating bodies, "barge" type semi-submersible floating bodies, and floating bodies with pendulum counterweights.

[0006] More specifically, this invention relates to a semi-submersible float, typically constructed of a steel or concrete base, usually in the form of a tripod with three (or four) cylindrical columns connected together by a metal structure. A ballast system allows part of the base to be submerged in water, thus ensuring structural stability. This structure is characterized by its large size and shallow draft.

[0007] For example, reference may be made to publication FR 3,064,973, which describes a semi-submersible hybrid floating structure comprising a central column and three external columns connected to the central column via pontoon-shaped supports.

[0008] See also the public texts FR 2,079,204 and WO 2018 / 197644, which describe semi-submersible floating structures equipped with passive ballast systems.

[0009] These types of floats have the advantage of simple design. However, they lack an active ballast system. The main purpose of active ballast is to distribute a certain amount of fluid between the different watertight compartments of the float to correct the float's tilt angle during operation. This can limit the tilt angle of the mast supporting the turbine, thereby increasing power generation and reducing the load caused by mast tilting. Summary of the Invention

[0010] Therefore, a semi-submersible floating body equipped with an active ballast system is needed.

[0011] According to the present invention, this objective is achieved by an active centralized ballast method for a semi-submersible floating body for an offshore wind turbine, the floating body comprising at least four columns, including a central column and three external columns, the external columns being connected to the central column via lower supports forming the pontoons, the method comprising the controlled and centralized distribution of ballast fluid between watertight compartments formed inside each pontoon to achieve adjustment of the floating body's tilt angle.

[0012] The active ballast method according to the present invention can reduce the total weight of the floating body by reducing fatigue load. Furthermore, the method can also reduce the overall size of the floating body, thereby facilitating access to some ports and adapting to dry transport methods. According to the method of the present invention, by reducing the inclination angle of the mast supporting the turbine, the power generation of the turbine can also be increased.

[0013] Ballast fluid can be dispensed between compartments located inside the longitudinal end of each pontoon near the outer pillar.

[0014] As an additional method, the method may also include: the distribution of ballast fluid between additional watertight compartments located at the height of a hydrodynamic damping plate arranged around at least a portion of the external column.

[0015] The present invention also relates to a semi-submersible float for an offshore wind turbine, the float having an active and centralized ballast system, the float comprising at least four columns, including a central column and three outer columns, the outer columns being connected to the central column via lower supports forming pontoons, each pontoon comprising at least one watertight compartment forming a ballast area, the float also being provided with a device for controlling and independently distributing ballast fluid between the compartments of the float, thereby achieving adjustment of the float's tilt angle.

[0016] Each pontoon may include a longitudinally extending compartment near the outer pillar, and these compartments are interconnected by a network of pipes connected to a network of pumps.

[0017] As an additional feature, the float may also include an additional watertight compartment located at the height of the hydrodynamic damping plate, which is arranged around at least a portion of each external column and interconnected by a network of pipes connected to a network of pumps.

[0018] Preferably, the network formed by the pumps is located inside the central column and at the lower part of the central column.

[0019] The pontoons of the float preferably each include a set of planar panels, and each pontoon has a polyhedral cross-section.

[0020] In this case, the external columns can each be cylindrical. Alternatively, the external columns can comprise a set of planar panels, with each external solid having a polyhedral cross-section.

[0021] Preferably, the flat panels of each pontoon are assembled together at the edges, which extend along the length between the two posts and are connected to the posts at the ends in each length direction by transition pieces to form rounded corners.

[0022] The central pillar of the float may be truncated cone-shaped. Alternatively, the central pillar may be polyhedral in shape.

[0023] The present invention also relates to an offshore wind turbine that includes a floating body as described above. Attached Figure Description

[0024] Figure 1 A semi-submersible float in one embodiment of the present invention is shown in perspective view.

[0025] Figure 2 yes Figure 1 View on cut plane II.

[0026] Figure 3 yes Figure 2 Perspective view.

[0027] Figure 4 yes Figure 1 A cross-sectional view of the floating body on a horizontal plane.

[0028] Figure 5 This is a cross-sectional view of a semi-submersible float along the height direction in another embodiment of the present invention. Detailed Implementation

[0029] Figure 1 A perspective view shows a semi-submersible floating body 2 for an offshore wind turbine according to a first embodiment of the present invention.

[0030] In this embodiment, the floating body 2 includes four vertical columns: one for housing the wind turbine mast ( Figure 1The central column 4 (not shown in the image) and three external columns 6 are connected to the central column 4 via supports that form the lower pontoon 8.

[0031] More specifically, the lower pontoon 8 and the outer column 6 are separated from each other at an angle of 120° to form a star-shaped structure.

[0032] Furthermore, at least the pontoons are composed of multiple flat panels assembled together. More specifically, in Figure 1 In the illustrated embodiment, each lower pontoon 8 is assembled from four planar panels 81 to 84, forming a cuboid. Figure 1 Only planar panels 81 and 84 are visible in the middle.

[0033] Of course, it is also possible to imagine that each pontoon is made up of a different number of flat panels (e.g., five, six, etc.).

[0034] Preferably, the flat panels of each pontoon are assembled together at edges 10, which extend along the length between the two posts and are connected to the posts at the ends in each length direction by transition pieces 12 to form rounded corners.

[0035] The rounded edge 10 of the pontoon is connected to the vertical column of the buoy through transition pieces 12 at its two ends in the two length directions, so that the quarter circle shape is switched to a right angle shape.

[0036] It is worth noting that, in Figure 1 In the illustrated embodiments, the outer columns 6 of the float 2 are all approximately cylindrical in shape. Of course, the invention is also applicable to those whose outer columns are composed of a set of planar panels to present a polyhedral shape (see the applicant's patent application FR 23 01328 filed on February 13, 2023).

[0037] It should also be noted that, in Figure 1 In the illustrated embodiment, the central column 4 of the float 2 used to house the wind turbine mast is a downwardly flared truncated cone shape. Of course, the invention is also applicable to floats with a cylindrical central column.

[0038] In addition, Figures 2 to 4 In the embodiment of the invention shown, each lower buoy 8 of the float encloses a watertight inner compartment 14 that forms a ballast area. The watertight inner compartment is located at the end of the buoy along its length and on one side of the outer column 6.

[0039] In addition, these watertight compartments 14 are interconnected by a pipe network 16, which is connected to a network formed by pumps 18, preferably located in the lower part of the interior of the central column 4 of the float.

[0040] like Figure 2 and Figure 3 As shown, these compartments 14 extend to the entire width and height of the pontoon 8 and are defined in the longitudinal direction by two watertight bulkheads 14a. A pipe 16 leads into the interior of the space defined in the longitudinal direction between the two watertight bulkheads 14a.

[0041] A control system (not shown) drives a network of pumps 18 to distribute ballast fluid (typically water, especially seawater) between different compartments 14 of the float, thereby correcting the float's tilt angle during the operational phase (typically around 0 to 3 degrees).

[0042] To achieve this correction of the float's tilt angle, it is usually necessary to transfer 100 to 500 tons of ballast fluid between different compartments of the float.

[0043] Figure 5 Another embodiment of the invention is shown, wherein the float 2' (with Figures 1 to 4 Compared to the float in the embodiment, it also includes hydrodynamic damping plates 20, which are arranged around at least a portion of the outer column 6 and located at the lower part of the outer column.

[0044] These hydrodynamic damping plates 20, also known as heave plates, are used to suppress the motion of a floating body under the influence of swells and wind. These plates effectively increase the added mass and drag of the floating body, thereby maximizing the difference between the natural period of the floating body and the wave period, thus weakening the excitation on the floating body and suppressing its motion as much as possible.

[0045] exist Figure 5 In the illustrated embodiment, two hydrodynamic damping plates 20 are provided arranged around each of the outer columns 6 of the float. For each outer column, the two plates 20 are symmetrical with respect to the vertical plane of symmetry P of the float 8.

[0046] Of course, other shapes and positions of these hydrodynamic damping plates can be envisioned. For example, they could be disc-shaped and placed below each of the outer pillars of the buoy.

[0047] Similarly, in this embodiment, each hydrodynamic damping plate 20 encloses a watertight compartment 22, forming an additional ballast area, and the compartments 22 of the same external column are interconnected by an additional pipe network 24 connected to the network formed with the pump 18.

[0048] Therefore, in this embodiment, the tilt angle of the float 2' is adjusted by distributing ballast fluid between the compartments 14 of the float and between the compartments 22 of the different hydrodynamic damping plates 20.

Claims

1. An active centralized ballast method for a semi-submersible floating body (2; 2') for an offshore wind turbine, characterized in that, The float comprises at least four columns, including a central column (4) and three external columns (6), the external columns being connected to the central column via lower supports forming pontoons (8), each pontoon (8) comprising a set of planar panels (81 to 84), and each pontoon (8) having a polyhedral cross-section, the planar panels (81 to 84) of each pontoon being assembled together at an edge (10) extending along the length between two columns and forming a rounded corner at each end of the length direction by a transition piece (12) connected to the column, the method comprising controlled and centralized distribution of ballast fluid between watertight compartments (14; 22) formed inside each pontoon (8) to achieve adjustment of the inclination angle of the float.

2. The method according to claim 1, characterized in that, The ballast fluid is distributed between compartments (14) located inside the longitudinal end of each pontoon (8) on the side near the outer column (6).

3. The method according to any one of claims 1 and 2, characterized in that, The method further includes: the ballast fluid is distributed between additional watertight compartments (22), which are located at the height of the hydrodynamic damping plate (20) arranged around at least a portion of the external column (6).

4. A semi-submersible floating body (2; 2') for offshore wind turbines, characterized in that, Having active and centralized ballast functions, it includes at least four columns, including a central column (4) and three external columns (6), the external columns being connected to the central column via lower supports forming pontoons (8), each pontoon (8) including a set of planar panels (81 to 84), and each pontoon having a polyhedral cross-section, the planar panels (81 to 84) of each pontoon being assembled together at an edge (10), the edge extending along the length between two columns and forming a rounded corner at each end of the length direction by a transition piece (12) connected to the column, each pontoon including at least one watertight compartment (14; 22) forming a ballast area, the pontoon also including devices (16, 18, 24) for distributing ballast fluid between the compartments of the pontoon in a controllable and independent manner, thereby achieving adjustment of the pontoon's tilt angle.

5. The float according to claim 4, characterized in that, Each pontoon (8) includes a compartment (14) located at one end along the length of the outer column, and these compartments are interconnected by a network of pipes (16) connected to the network formed by the pumps (18).

6. The buoy according to any one of claims 4 and 5, characterized in that, Each pontoon also includes an additional watertight compartment (22) located at the height of a hydrodynamic damping plate (20) arranged around at least a portion of each external column (6), the additional compartments being interconnected by a network of pipes (24) connected to a network of pumps (18).

7. The buoyancy body according to any one of claims 5 and 6, characterized in that, The network formed by the pump (18) is located inside the central column (4) and at the lower part of the central column.

8. The buoy according to claim 4, characterized in that, The external columns (6) are all cylindrical.

9. The buoy according to claim 4, characterized in that, Each of the external columns (6) includes a set of planar panels, and each has a polyhedral cross-section.

10. The buoyant according to any one of claims 4 to 9, characterized in that, The central column (4) is truncated conical in shape.

11. The buoyancy body according to any one of claims 4 to 9, characterized in that, The central column (4) is in the shape of a polyhedron.

12. An offshore wind turbine, characterized in that, Includes the float according to any one of claims 4 to 11.

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