Semi-submersible floating wind turbine foundation with moonpool structure

Abstract

The application discloses a semi-submersible floating wind turbine foundation with moon pool structure, comprising a plurality of pontoons, the center of each pontoon is a hollow moon pool structure, the top of each pontoon is provided with a cover plate for closing the top of each moon pool structure and forming a closed air cabin above the moon pool; each pontoon is connected by a support structure to form a foundation platform. The application forms a closed air cabin above the moon pool, when the pontoon swings, the gas in one side of the air cabin is compressed to generate positive pressure, and the other side generates negative pressure to generate a restoring moment, so that the moon pool has its own characteristics, and the swing amplitude of the foundation platform is further reduced by the restoring moment. At the same time, by combining the vibration water column characteristics of the moon pool and the aerodynamic characteristics of the air cabin with the self structural dynamic characteristics of the semi-submersible wind turbine foundation, the suppression ability to low-frequency and high-frequency waves is enhanced, so that the widely applicable roll reduction effect is achieved, and the stability of the foundation platform is further improved.

Description

Technical Field

[0001] This invention relates to the field of wind turbine foundation technology, and in particular to a semi-submersible floating wind turbine foundation with a moon pool structure. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] With the increasing global demand for renewable energy, offshore wind power has become an important direction for developing wind energy resources. However, in deep-sea areas, due to the greater water depth, traditional fixed foundations are difficult to apply economically and effectively, and floating wind turbines are gradually becoming the main trend in the development of deep-sea wind power.

[0004] Floating wind turbine foundations are mainly classified into column-type, semi-submersible, barge-type, and tension leg-type. Among them, the semi-submersible floating wind turbine, as a typical structural form, has good adaptability in complex sea conditions due to its excellent buoyancy distribution and stability. However, the traditional semi-submersible floating wind turbine structure suffers from insufficient dynamic stability when dealing with strong winds and waves and complex flow fields. Under the action of strong winds and waves, the floating structure is prone to significant swaying and tilting, affecting the power generation efficiency and structural safety of the wind turbine.

[0005] To further improve the dynamic stability and adaptability of floating wind turbine foundations, researchers have recently explored the introduction of novel design structures and dynamic response control technologies. Among these, the moon pool structure, as an emerging fluid dynamics application, demonstrates significant anti-sway effects and wind and wave resistance by utilizing the nonlinear interaction between the water within the moon pool and the external environment. For example, patent publications CN112177859A and CN110949633A both present examples of applying moon pools to floating wind turbine foundations.

[0006] However, all current wind turbine foundations with moon pool structures are barge-type foundations. There are no cases of moon pools being set up for semi-submersible wind turbine foundations. The main reason for this is that semi-submersible wind turbine foundations do not have enough space to create a sufficiently large moon pool like barge-type foundations, thus limiting the effectiveness. Therefore, this application provides a semi-submersible floating wind turbine foundation with a moon pool structure that has good stability and is suitable for use with semi-submersible wind turbine foundations. Summary of the Invention

[0007] The purpose of this invention is to address the aforementioned shortcomings by providing a semi-submersible floating wind turbine foundation with a moon pool structure.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0009] A semi-submersible floating wind turbine foundation with a moon pool structure includes multiple pontoons, each pontoon having a hollow moon pool structure at its center, and each pontoon having a cover plate at its top. The cover plate is used to close the top of each moon pool structure and form a sealed air chamber above the moon pool.

[0010] The pontoons are connected by a support structure to form a base platform, which is used to install the wind turbine.

[0011] Furthermore, each pontoon is provided with a rib at its center, which is used to divide the hollow moon pool structure into multiple smaller hollow moon pool structures and to divide the sealed air chamber into multiple smaller sealed air chambers.

[0012] Furthermore, the cover plate is a split type, comprising multiple split plates, each split plate corresponding to a small hollow moon pool structure, and can be detachably set on the top of each small hollow moon pool structure. By removing the corresponding split plate, the number of small sealed air chambers can be controlled, thereby adjusting the oscillation characteristics of the water in the moon pool and the aerodynamic characteristics inside the air chamber.

[0013] Furthermore, it also includes a ballast system comprising anti-roll tanks disposed between each pontoon and the middle of the base platform, the anti-roll tanks being filled with fluid that is capable of flowing within the anti-roll tanks.

[0014] Furthermore, the anti-roll tank has a U-shaped longitudinal section, and the ballast system also includes an air pump for pumping air to one end of the corresponding foundation platform of the anti-roll tank, so that the liquid levels at both ends of the U-shape in the anti-roll tank are not on the same horizontal line.

[0015] Furthermore, multiple first sway plates are distributed vertically on the inner wall of the moon pool.

[0016] Furthermore, a second heave plate is provided at the lower edge of the pontoon.

[0017] Furthermore, it also includes a mooring system comprising multiple mooring lines, one end of which is connected to each buoy, and the other end of which is anchored to the seabed, for securing the base platform in a designated location.

[0018] Furthermore, the support structure includes a support plate connecting the bottom of each pontoon, and a first truss connecting the middle of the support plate and the top of the pontoon, wherein the support plate, pontoon and first truss form a triangular structure.

[0019] Furthermore, the fan is located in the middle of the support plate, and the support plate also includes a second truss, one end of which is connected to the fan, and the other end of which is connected to the top of the corresponding pontoon.

[0020] The beneficial effects of this invention are reflected in:

[0021] This invention, by forming a sealed air chamber above the moon pool, creates a positive pressure on one side of the air chamber and a negative pressure on the other side, generating a restoring torque, when the pontoon oscillates. In this way, while retaining its inherent characteristics, the moon pool further reduces the sway amplitude of the foundation platform through the restoring torque. Simultaneously, by optimizing and adjusting the vibration characteristics of the water column and the aerodynamic characteristics of the air chamber, and combining them with the structural dynamic characteristics of the semi-submersible wind turbine foundation, the ability to suppress low-frequency and high-frequency waves is enhanced, thus achieving a widely applicable sway reduction effect. Furthermore, the cover plate also creates a complete working surface on top of the pontoon, facilitating worker operations and equipment installation. Attached Figure Description

[0022] Figure 1 This is an overall view of the semi-submersible floating wind turbine foundation with a moon pool structure described in this invention (cover plate omitted).

[0023] Figure 2 This is a diagram showing the distribution structure of the first heave plate in this invention;

[0024] Figure 3 This is a diagram showing the state of the moon pool inside when the basic platform described in this invention is tilted.

[0025] In the picture:

[0026] 1. Buoy; 11. Rib; 12. First heave plate; 13. Second heave plate; 2. Cover plate; 3. Air chamber; 4. Anti-roll tank; 5. Mooring system; 6. Support structure; 61. Support plate; 62. First truss; 63. Second truss. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Please see Figure 1-3 The present invention discloses a semi-submersible floating wind turbine foundation with a moon pool structure, including multiple pontoons 1, each pontoon 1 having a hollow moon pool structure at its center, and each pontoon 1 having a cover plate 2 on its top, which is used to close the top of each moon pool structure, forming a sealed air chamber 3 above the moon pool.

[0029] Each pontoon 1 is connected by a support structure 6 to form a base platform, which is used to install the wind turbine.

[0030] In practice, buoy 1 provides the primary buoyancy and typically employs a multi-buoy 1 configuration (such as three-buoy 1 or four-buoy 1). The moon pool, located inside buoy 1, primarily absorbs wave energy through water oscillations, thereby reducing the platform's sway amplitude. The water within the pool, due to inertia and wave interaction, generates strong free surface oscillations. These oscillations, through water flow friction and energy dissipation, convert wave energy into heat or eddies, reducing the direct impact of external waves on the platform. When the oscillation frequency of the water within the moon pool matches the platform's dynamic characteristics (such as the natural frequencies of roll and pitch), the oscillation motion can be amplified, dissipating wave energy and further reducing the platform's sway amplitude. By optimizing the size, shape, and depth of the moon pool, it can absorb wave energy of different frequencies over a wide frequency range, enhancing the platform's adaptability to various sea conditions.

[0031] This invention, by forming a sealed air chamber 3 above the moon pool, allows for air circulation when the float 1 oscillates (see attached diagram). Figure 3 The compression of gas in one air chamber 3 generates positive pressure, while the other side generates negative pressure, creating a restoring torque (i.e., the upward thrust of the positive pressure on the pontoon 1 and the downward pull of the negative pressure on the pontoon 1). This further reduces the swaying amplitude of the foundation platform. Simultaneously, since the pontoon 1 of the semi-submersible wind turbine foundation is typically located at the point of greatest heave, roll, and pitch motion, the movement of the buoy can cause significant movement of the water in the moon pool. At the same time, the restoring torque generated in the moon pool at this location is even greater, further reducing the swaying amplitude of the foundation platform and improving its stability. Furthermore, the cover plate 2 creates a complete working surface on top of the pontoon 1, facilitating worker operations and equipment installation.

[0032] In one embodiment, each pontoon 1 has a rib 11 at its center. This rib 11 is used to divide the hollow moon pool structure into multiple smaller hollow moon pool structures and to divide the sealed air chamber 3 into multiple smaller sealed air chambers 3, which are not interconnected. This design effectively improves the overall strength and regulates the oscillation characteristics of the water in the moon pool. Furthermore, it allows for the formation of multiple smaller sealed air chambers on top of each smaller hollow moon pool structure, adjusting the aerodynamic characteristics within the sealed air chambers. The optimized structural design of the rib arrangement further enhances the stability of the platform.

[0033] It should be noted that although the setting of rib 11 will affect the sloshing of the water in the moon pool and reduce the moon pool's own anti-sway effect to some extent, as mentioned in the background section, due to the limited size of the moon pool in the semi-submersible wind turbine foundation, the moon pool's own anti-sway effect has a limited impact on the foundation platform's movement. However, by setting rib 11 to optimize and adjust the vibration water column characteristics and air chamber aerodynamic characteristics of the moon pool, the suppression ability of low-frequency and high-frequency waves is enhanced, thereby achieving a widely applicable anti-sway effect that is far greater than the contribution of the moon pool's own anti-sway effect to the platform's stability. Therefore, for semi-submersible wind turbine foundations with a moon pool structure, the setting of rib 11 has more advantages than disadvantages.

[0034] In one embodiment, the cover plate 2 is a split type, comprising multiple split plates, each corresponding to a small hollow moon pool structure. It is detachably mounted on top of each small hollow moon pool structure. By removing the corresponding split plate, the number of small sealed air chambers 3 can be controlled, thereby adjusting the oscillation characteristics of the water in the moon pool and the aerodynamic characteristics within the air chambers 3. This design allows for adjustment according to different aquatic environments, enhancing the platform's adaptability to various sea conditions.

[0035] In one embodiment, a ballast system is also included, comprising an anti-roll tank 4 disposed between each pontoon 1 and the middle of the base platform, the anti-roll tank 4 being filled with fluid and capable of flowing within the anti-roll tank 4.

[0036] In practice, when the base platform sways, the water in the anti-roll tank 4 experiences relative flow due to inertia. This free surface movement interacts with the platform's swaying, creating an internal damping force to counteract external waves. The water in the anti-roll tank 4 flows between the tank walls, dissipating energy due to friction and fluid viscosity, thus reducing the platform's sway amplitude. This dissipation effect is particularly effective against long-period rolls and pitches caused by low-frequency waves. Through the synergistic effect of the moon pool and the anti-roll tank 4, the combined effect broadens the platform's anti-sway frequency range and improves the overall anti-sway performance. By optimizing the design parameters of the moon pool and the anti-roll tank 4 (such as water volume, compartment dimensions, and opening form) to match the platform's natural frequency, the stability of the wind turbine under complex sea conditions is improved.

[0037] It should be noted that the anti-rolling water tank 4, which is part of the ballast system, is existing technology. In addition to the water tank itself, it is equipped with a water pump to control the water volume in the water tank. Since this ballast system is common knowledge to those skilled in the art, it will not be described in detail here. It is only emphasized that the anti-rolling water tank 4 can be combined with the moon pool and work together.

[0038] In one embodiment, the anti-roll tank 4 has a U-shaped longitudinal section, and the ballast system also includes an air pump (not shown in the figure) for pumping air to one end of the corresponding foundation platform of the anti-roll tank 4 so that the liquid levels at both ends of the U-shape in the anti-roll tank 4 are not on the same horizontal line.

[0039] In practice, this method allows the water in the anti-roll tank 4 to flow to the other end, thereby adjusting the buoyancy and center of gravity of the base platform and further improving the anti-roll effect.

[0040] It should be noted that the anti-roll tank 4U-shaped has vents at both ends that connect to the outside. By controlling the opening and closing of these vents in conjunction with an air pump, the buoyancy and center of gravity of the base platform can be adjusted. Since these vents and related structural features are already present in the existing anti-roll tank 4, they will not be elaborated upon here. This section only emphasizes the structural form of the anti-roll tank 4 and how adding an air pump to pump air into the anti-roll tank 4 can adjust the buoyancy and center of gravity of the base platform, thereby changing the anti-roll effect.

[0041] In one embodiment, a plurality of first sag plates 12 are distributed vertically on the inner wall of the moon pool to further increase the damping effect.

[0042] In specific implementation, the first heave plate 12 consists of multiple blocks. The first end of each block is connected to the inner wall of the moon pool, and the other end extends toward the center of the moon pool. The multiple blocks are distributed in a ring inside the moon pool and arranged in a vertical direction.

[0043] In one embodiment, a second heave plate 13 is provided at the lower edge of the pontoon 1 to increase the damping effect of the pontoon 1.

[0044] In one embodiment, the system also includes a mooring system 5, which includes multiple mooring lines, one end of which is connected to each buoy 1 and the other end is anchored to the seabed to fix the base platform in a designated position.

[0045] In one embodiment, the support structure 6 includes a support plate 61 connecting the bottom of each pontoon 1, and a first truss 62 connecting the middle of the support plate 61 and the top of the pontoon 1. The support plate 61, the pontoon 1 and the first truss 62 form a triangular structure.

[0046] The fan is located in the middle of the support plate 61, and the platform also includes a second truss 63. One end of the second truss 63 is connected to the fan, and the other end is connected to the top of the corresponding pontoon 1. This further improves the overall rigidity and stability of the foundation platform.

[0047] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0048] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0049] Additionally, "multiple" refers to two or more.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A semi-submersible floating wind turbine foundation with a moon pool structure, characterized in that, It includes multiple pontoons (1), each pontoon (1) has a hollow moon pool structure at its center, and each pontoon (1) has a cover plate (2) on its top. The cover plate (2) is used to close the top of each moon pool structure and form a sealed air chamber (3) above the moon pool. Each pontoon (1) is supported and connected by a support structure (6) to form a base platform, which is used to install the fan; Each pontoon (1) has a rib plate (11) at its center. The rib plate (11) is used to divide the hollow moon pool structure into multiple small hollow moon pool structures and to divide the sealed air chamber (3) into multiple small sealed air chambers (3). The cover plate (2) is a split type, including multiple split plates. Each split plate corresponds to a small hollow moon pool structure and can be detachably set on the top of each small hollow moon pool structure. By removing the corresponding split plate, the number of small sealed air chambers (3) can be controlled, thereby adjusting the oscillation characteristics of the water in the moon pool and the aerodynamic characteristics inside the air chamber (3).

2. The semi-submersible floating wind turbine foundation with a moon pool structure according to claim 1, characterized in that, It also includes a ballast system, which includes anti-roll tanks (4) located between each pontoon (1) and the middle of the base platform. The anti-roll tanks (4) are filled with fluid and the fluid can flow within the anti-roll tanks (4).

3. The semi-submersible floating wind turbine foundation with a moon pool structure according to claim 2, characterized in that, The anti-roll tank (4) has a U-shaped longitudinal section. The ballast system also includes an air pump for pumping air to one end of the corresponding foundation platform of the anti-roll tank (4) so ​​that the liquid levels at both ends of the U-shape in the anti-roll tank (4) are not on the same horizontal line.

4. The semi-submersible floating wind turbine foundation with a moon pool structure according to claim 1, characterized in that, Multiple first sag plates (12) are distributed vertically on the inner wall of the moon pool.

5. The semi-submersible floating wind turbine foundation with a moon pool structure according to claim 1, characterized in that, A second heave plate (13) is provided at the lower edge of the pontoon (1).

6. The semi-submersible floating wind turbine foundation with a moon pool structure according to claim 1, characterized in that, It also includes a mooring system (5), which includes multiple mooring lines, one end of which is connected to each buoy (1), and the other end is anchored to the seabed to fix the base platform in a designated position.

7. The semi-submersible floating wind turbine foundation with a moon pool structure according to claim 1, characterized in that, The support structure (6) includes a support plate (61) connecting the bottom of each pontoon (1) and a first truss (62) connecting the middle of the support plate (61) and the top of the pontoon (1). The support plate (61), the pontoon (1) and the first truss (62) form a triangular structure.

8. The semi-submersible floating wind turbine foundation with a moon pool structure according to claim 7, characterized in that, The fan is located in the middle of the support plate (61) and also includes a second truss (63). One end of the second truss (63) is connected to the fan, and the other end is connected to the top of the corresponding pontoon (1).

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