Offshore wind turbine and four-buoy semi-submersible floating body platform and low-frequency tuning liquid column damper thereof

Abstract

The low-frequency tuning liquid column damper comprises three horizontal tuning liquid columns which are annularly and evenly distributed, and vertical tuning liquid columns are arranged at the outward ends of the three horizontal tuning liquid columns in the radial direction correspondingly; the horizontal tuning liquid column comprises a horizontal snakelike pipeline, and a first horizontal pipe section and a second horizontal pipe section are arranged at the two ends of the horizontal snakelike pipeline respectively; the vertical tuning liquid column comprises a vertical snakelike pipeline, and a vertical pipe section is arranged at the lower end of the vertical snakelike pipeline; the horizontal tuning liquid column and the vertical tuning liquid column are connected through the adjacent first horizontal pipe section and vertical pipe section; the three adjacent second horizontal pipe sections among the three horizontal tuning liquid columns are communicated with one another; a damping valve is arranged in the second horizontal pipe section, and the horizontal tuning liquid column and the vertical tuning liquid column are filled with damping liquid. The invention further discloses a four-buoy semi-submersible type floating body platform and an offshore wind turbine, and the four-buoy semi-submersible type floating body platform and the offshore wind turbine can adapt to the low-frequency vibration characteristic of the semi-submersible type platform.

Description

Technical Field

[0001] The present invention belongs to the technical field of offshore wind power generation, and particularly relates to an offshore wind turbine, a four-buoy semi-submersible floating body platform thereof, and a low-frequency tuned liquid column damper. Background Art

[0002] In the face of severe energy shortage and air pollution problems, the development of renewable energy represented by wind energy has been put on the agenda. The prospects for deep-sea wind power are broad. After the water depth is greater than 40 meters, floating wind turbines replace fixed wind turbines as the main force in wind power. Floating platforms include tension leg platforms (TLP), semi-submersible platforms (Semi-Sub), barge platforms (Barge), and single-column platforms (Spar). Among them, the semi-submersible platform has strong application prospects due to its advantages such as good water depth adaptability.

[0003] A semi-submersible wind turbine is a rigid-flexible hybrid structure in which a floating platform is anchored by a mooring system and is fixedly connected to a high and flexible tower to carry a nacelle and flexible blades. Among them, the four-buoy semi-submersible floating body platform has strong competitiveness in the wind power market in Eurasia due to its excellent wave resistance performance. Since the floating body platform will generate low-frequency roll and pitch responses under wind and wave loads, even a small rotation of the lower floating foundation will be transmitted to the upper structure through the tower, causing large-amplitude movements at the nacelle position, resulting in turbulent wind field disorders and triggering strong wind-wave coupling vibration effects, which will exacerbate the fatigue damage of the whole machine.

[0004] Therefore, adopting advanced control technology to adjust the movement of the platform is the key measure to improve the overall performance and stability of offshore wind turbines. In the prior art, traditional tuned liquid column dampers (TLCD) mostly use straight pipelines, which have problems such as low space utilization rate, narrow frequency adjustment range, and limited installation space, and are difficult to adapt to the low-frequency vibration characteristics of semi-submersible platforms. Summary of the Invention

[0005] In view of this, in order to solve the deficiencies of existing tuned liquid column dampers, the purpose of the present invention is to provide an offshore wind turbine, a four-buoy semi-submersible floating body platform thereof, and a low-frequency tuned liquid column damper.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A low-frequency tuned liquid column damper includes three horizontally tuned liquid columns arranged in a circular pattern, and vertical tuned liquid columns are respectively provided at the radially outward ends of the three horizontally tuned liquid columns;

[0008] The horizontally tuned liquid column includes a horizontal serpentine pipeline, and a first horizontal pipe section and a second horizontal pipe section are respectively provided at both ends of the horizontal serpentine pipeline;

[0009] The vertical tuned liquid column includes a vertical serpentine pipe, and a vertical pipe section is provided at the lower end of the vertical serpentine pipe;

[0010] The horizontal tuned liquid column and the vertical tuned liquid column are connected by the adjacent first horizontal pipe section and the vertical pipe section;

[0011] Three adjacent second horizontal pipe sections among the three horizontal tuned liquid columns are connected to each other;

[0012] A damping valve is provided in the second horizontal pipe section, and damping liquid is filled in the horizontal tuned liquid column and the vertical tuned liquid column.

[0013] Further, the damping liquid is a mixture of seawater and ethylene glycol, and the density range is 1150-1250 kg / m 3 , and the freezing point ≤ -30 °C.

[0014] Further, the ratio of the radius of curvature of the bending section of the horizontal serpentine pipe and the vertical serpentine pipe to the pipe diameter is 2.5-3.0.

[0015] Further, the opening ratio of the damping valve can be continuously adjusted between 0% and 80%, and the regulation range of the liquid column damping ratio is 0.03-0.15.

[0016] Further, the adjacent first horizontal pipe section and the vertical pipe section are transitionally connected through an arc pipe with an included angle of 90°.

[0017] The present invention also proposes a four-buoy semi-submersible floating body platform, which includes a central buoy and three peripheral buoys. The three peripheral buoys are annularly and evenly arranged relative to the axis of the central buoy; horizontal connecting cylinders are respectively provided between the central buoy and the three peripheral buoys in the radial direction, and the horizontal connecting cylinders connect the central buoy and the corresponding peripheral buoy; it also includes the low-frequency tuned liquid column damper as described above;

[0018] The three vertical tuned liquid columns are respectively arranged in the three peripheral buoys;

[0019] The three horizontal tuned liquid columns are respectively arranged in the three horizontal connecting cylinders.

[0020] Further, the first horizontal pipe section and the second horizontal pipe section are fixed to the pipe wall of the horizontal connecting cylinder through a rigid support. The rigid support is made of double-layer anti-corrosion steel plates, and the surface of the double-layer anti-corrosion steel plates is coated with a polyurethane shock-absorbing layer;

[0021] The vertical pipe section is fixed to the inner wall of the cabin of the peripheral buoy through a multi-directional articulated flexible connector. The multi-directional articulated flexible connector allows the vertical pipe section to swing multi-directionally within a range of ±3°, adapting to the dynamic deformation of the platform.

[0022] Further, the total mass of the low-frequency tuned liquid column damper accounts for 15%-20% of the ballast water mass of the four-floater semi-submersible floating body platform.

[0023] Further, a central base is provided inside the central floater below the horizontal tuned liquid column. A lower support ring for supporting three adjacent second horizontal pipe segments is provided on the central base, and an upper support ring located above the three adjacent second horizontal pipe segments is provided above the lower support ring; the lower support ring and the upper support ring are fixedly connected to the central base by bolts.

[0024] The present invention also provides an offshore wind turbine, including a tower, a nacelle and blades, and the bottom of the tower is provided with the four-floater semi-submersible floating body platform as described above.

[0025] The beneficial effects of the present invention are as follows:

[0026] For the four-floater semi-submersible floating body platform of the present invention, by arranging low-frequency tuned liquid column dampers in the central floater, the peripheral floaters and the horizontal connecting cylinders, and forming a structure in which the three vertical tuned liquid columns and the three horizontal tuned liquid columns of the damper are in a trident star layout, the damper structure can be optimized, the liquid column inertia force can be evenly dispersed, the multi-degree-of-freedom motion of the floating body platform can be adapted, and local stress concentration can be reduced; the serpentine pipe design is adopted inside the damper, and the bending structure of the serpentine pipe is used to extend the liquid column movement path, enhance the low-frequency energy dissipation efficiency, and improve the frequency matching accuracy; by arranging a damping valve in the second horizontal pipe segment and adjusting the dynamic opening of the damping valve to incorporate the dynamic damping adjustment technology, the liquid column damping characteristics can be optimized in real time to meet the vibration control requirements under complex sea conditions. Description of the Drawings

[0027] In order to make the objectives, technical solutions and beneficial effects of the present invention clearer, the following drawings are provided for illustration:

[0028] Figure 1 It is a schematic structural diagram of an embodiment of the offshore wind turbine of the present invention;

[0029] Figure 2 It is a schematic structural diagram of the four-floater semi-submersible floating body platform;

[0030] Figure 3 It is a partial enlarged view of the four-floater semi-submersible floating body platform.

[0031] Description of the reference numerals:

[0032] 10 - Tower; 11 - nacelle; 12 - blade; 20 - four - pontoon semi - submersible floating platform; 21 - central pontoon; 22 - peripheral pontoon; 23 - horizontal connecting cylinder; 24 - central base; 25 - lower support ring; 26 - upper support ring; 30 - low - frequency tuned liquid column damper; 31 - horizontal tuned liquid column; 311 - horizontal serpentine pipe; 312 - first horizontal pipe section; 313 - second horizontal pipe; 32 - vertical tuned liquid column; 321 - vertical serpentine pipe; 322 - vertical pipe section; 33 - arc pipe; 40 - damping valve. Detailed implementation manners

[0033] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it. However, the embodiments given are not intended to limit the present invention.

[0034] As Figure 1 shown, the offshore wind turbine of this embodiment includes a tower 10, a nacelle 11 and blades 12. A four - pontoon semi - submersible floating platform 20 is provided at the bottom of the tower 10. The four - pontoon semi - submersible floating platform 20 of this embodiment includes a central pontoon 21 and three peripheral pontoons 22. The three peripheral pontoons 22 are arranged in a circular and uniform distribution relative to the axis of the central pontoon 21, that is, the angle between the axes of any two adjacent peripheral pontoons 22 is 120°, and the angle between the axis of the central pontoon 21 and the axes of the peripheral pontoons 22 is 90°. The axes of the central pontoon 21 and the peripheral pontoons 22 are in the vertical direction. Horizontal connecting cylinders 23 in the radial direction are respectively provided between the central pontoon 21 and the three peripheral pontoons 22, and the horizontal connecting cylinders 23 connect the central pontoon 21 and the corresponding peripheral pontoons 22.

[0035] As Figure 2As shown in the figure, the four-buoy semi-submersible floating body platform 20 of this embodiment further includes a low-frequency tuned liquid column damper 30. Specifically, the low-frequency tuned liquid column damper 30 of this embodiment includes three horizontally tuned liquid columns 31 arranged in a circular and uniform distribution. Vertically tuned liquid columns 32 are respectively provided at the radially outward ends of the three horizontally tuned liquid columns 31. That is, in this embodiment, the included angle between the axes of any two adjacent horizontally tuned liquid columns 31 is 120°, and the included angle between the axis of the horizontally tuned liquid column 31 and the axis of the vertically tuned liquid column 32 is 90°. The horizontally tuned liquid column 31 includes a horizontal serpentine pipe 311, and a first horizontal pipe section 312 and a second horizontal pipe 313 are respectively provided at both ends of the horizontal serpentine pipe 311. The vertically tuned liquid column 32 includes a vertical serpentine pipe 321, and a vertical pipe section 322 is provided at the lower end of the vertical serpentine pipe 321. Specifically, the horizontally tuned liquid column 31 and the vertically tuned liquid column 32 are connected by adjacent first horizontal pipe sections 312 and vertical pipe sections 322. The three adjacent second horizontal pipe sections 313 between the three horizontally tuned liquid columns 31 are connected to each other. A damping valve 40 is provided in the second horizontal pipe 313 of this embodiment, and damping liquid is filled in the horizontally tuned liquid column 31 and the vertically tuned liquid column 32. The damping liquid does not fill the vertically tuned liquid column 32, that is, the upper end of the vertical pipe section 322 or the vertical serpentine pipe 321 is not filled with damping liquid.

[0036] In this embodiment, the three vertically tuned liquid columns 32 are respectively arranged in three peripheral buoys 22. The three horizontally tuned liquid columns 31 are respectively arranged in three horizontal connecting cylinders 23.

[0037] Specifically, the low-frequency tuned liquid column damper 30 of this embodiment adopts a structural form of a three-pronged star layout composed of three vertically tuned liquid columns 32 and three horizontally tuned liquid columns 31. Its first horizontal pipe section 312 extends along the 120° equal division direction and is connected to the vertical pipe section 322 through a 90° arc pipe 33 for transition connection, that is, the adjacent first horizontal pipe section 312 and vertical pipe section 322 are connected through an arc pipe 33 with an included angle of 90° for transition connection. By extending the liquid column flow path through the serpentine bending section, the frequency matching ability of the floating body platform to the low-frequency vibration characteristics is significantly improved, and the natural frequency of the liquid column can be reduced to 0.05 Hz, which matches the low-frequency vibration characteristics of the floating body platform.

[0038] In the preferred implementation manner of this embodiment, the damping liquid is a mixture of seawater and ethylene glycol, with a ratio of 1:0.2 - 0.3, and the density range is 1150 - 1250 kg / m 3 , and with the anti-freezing characteristic of a freezing point ≤ -30°C, it can operate continuously throughout the year in harsh sea areas such as the North Sea. In this embodiment, the damping liquid 5 is a solution of seawater and ethylene glycol mixed in a volume ratio of 1:0.25, and the density is controlled at 1180 ± 20 kg / m 3, freezing point ≤ -30℃, injection volume is 70% of the total volume of the pipeline. Adjust the opening rate of the damping valve 40 to 50%-70%, so that the phase difference between the liquid column vibration and the platform vibration is stabilized at 180±5°, achieving the best vibration reduction effect.

[0039] In the preferred implementation of this embodiment, the curvature radius of the curved section of the horizontal serpentine pipe 311 and the vertical serpentine pipe 321 is 2.5-3.0. Under normal working conditions with wind and wave load coupling, compared with the maximum size of straight pipe TLCD that can be placed on a four-buoy semi-submersible floating platform, the vibration reduction efficiency of the low-frequency tuned liquid column damper 30 in this embodiment can be increased by 5% to 17% of the traditional TLCD; under extreme working conditions, the vibration reduction efficiency of the low-frequency tuned liquid column damper 30 will be higher, and the traditional TLCD may face the risk of failure.

[0040] In the preferred implementation of this embodiment, the opening rate of the damping valve 40 can be continuously adjusted between 0% and 80%, and the liquid column damping ratio can be adjusted in the range of 0.03-0.15. Compared with the traditional TLCD fixed damping hole design, the liquid column damping ratio can be dynamically adjusted (in the range of 0.03-0.15) to adapt to the platform vibration response characteristics under different sea conditions.

[0041] In a preferred implementation manner of this embodiment, the first horizontal pipe segment 312 and the second horizontal pipe segment 313 are fixed to the pipe wall of the horizontal connecting tube 23 by a rigid bracket. The rigid bracket is made of a double-layer anti-corrosion steel plate, and the surface of the double-layer anti-corrosion steel plate is covered with a polyurethane shock-absorbing layer. The rigid bracket is connected to the connector pre-embedded in the inner wall of the horizontal connecting tube 23 by a threaded connector.

[0042] In a preferred implementation manner of this embodiment, the vertical pipe section 322 is fixed to the inner wall of the cabin of the outer buoy 22 through a multi-directional articulated flexible connector. The multi-directional articulated flexible connector is composed of a spherical hinge and an articulated rod. The spherical hinge has a polytetrafluoroethylene bushing embedded in it, allowing the vertical pipe section 322 to swing in multiple directions within a range of ±3°. The articulated rod is connected to the anchor point of the bulkhead through a universal joint. A rubber gasket is arranged at the anchor point to absorb dynamic displacement and adapt to dynamic deformation of the platform.

[0043] In the preferred implementation of this embodiment, the total mass of the low-frequency tuned liquid column damper 30 accounts for 15%-20% of the ballast water mass of the four-buoy semi-submersible floating platform 20. The zero-added mass installation of the vibration reduction device is achieved through the mass substitution effect, which can reduce the overall mass of the platform by 7%-12% compared with the traditional TLCD.

[0044] In a preferred embodiment of the present embodiment, a central base 24 is provided inside the central buoy 21 below the horizontal tuned liquid column 31. A lower support ring 25 for supporting three adjacent second horizontal pipe sections 313 is provided on the central base 24. An upper support ring 26 is provided above the lower support ring 25 and above the three adjacent second horizontal pipe sections 313. The lower support ring 25 and the upper support ring 26 are fixedly connected to the central base 24 by bolts. That is, in the present embodiment, the lower support ring 25 and the upper support ring 26 are provided at the intersection of the three adjacent second horizontal pipe sections 313 to ensure the overall stability of the pipeline system under dynamic loads.

[0045] In this embodiment, both the low-frequency tuned liquid column damper 20 and the low-frequency tuned liquid column damper 30 are made of stainless steel and covered with a polyurethane shock-absorbing layer on the surface. Compared with the traditional TLCD carbon steel material, the seawater corrosion resistance is improved by more than 3 times, and the service life is extended to 25 years in a marine environment with a Cl- concentration ≥ 20,000 ppm.

[0046] After being verified by simulation software such as Ansys Aqwa and OpenFAST, for the 22MW four-buoy semi-submersible wind turbine equipped with the low-frequency tuned liquid column damper 20, under the coupled action of wind and wave loads, compared with the straight pipe TLCD with the largest size that can be placed on the four-buoy semi-submersible floating body platform, the vibration reduction efficiency of the low-frequency tuned liquid column damper 20 can be increased by up to 5% to 17% of the traditional TLCD; in extreme conditions, the traditional TLCD may face the risk of failure.

[0047] In view of the buoy-connected structure and low-frequency vibration characteristics of the four-buoy semi-submersible floating body platform of the offshore wind turbine in this embodiment, without changing the installation and maintenance method of the upper equipment of the wind power, the low-frequency tuned liquid column damper 30 with a special structure described above in this embodiment is arranged inside the four-buoy semi-submersible floating body platform 20. The traditional TLCD is designed in the form of a snake-shaped pipe with a trident star distribution, and the inertial force generated by the directional sloshing of the liquid inside the pipe is used to dissipate energy, thereby producing a vibration reduction effect; through the adjustable orifice ratio damper valve 40 arranged inside the horizontal pipe 312 and the horizontal pipe 313, the liquid column damping ratio is dynamically adjusted; at the same time, due to the special installation position of the low-frequency tuned liquid column damper 30, it can replace the ballast water of the same mass, effectively solving the problems of a large increase in the platform mass caused by installing traditional vibration control devices and the adverse effects brought by the change in the draft depth resulting in the change of the upper turbulent wind field.

[0048] The above-described embodiments are only preferred embodiments given to fully illustrate the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention. The protection scope of the present invention is subject to the claims.

Claims

1. A low frequency tuned liquid column damper, characterized in that: It comprises three horizontal tuning liquid columns evenly distributed in an annular manner, and a vertical tuning liquid column is respectively provided at one end of the three horizontal tuning liquid columns facing radially outwards; The horizontal tuning liquid column comprises a horizontal serpentine pipe, and two ends of the horizontal serpentine pipe are respectively provided with a first horizontal pipe section and a second horizontal pipe section; The vertical tuning liquid column comprises a vertical serpentine pipe, and a vertical pipe section is provided at the lower end of the vertical serpentine pipe; The horizontal tuning liquid column and the vertical tuning liquid column are connected via the adjacent first horizontal pipe section and vertical pipe section; Three adjacent second horizontal pipe sections between the three horizontal tuning liquid columns are connected; A damping valve is arranged in the second horizontal pipe section, and the horizontal tuning liquid column and the vertical tuning liquid column are filled with damping liquid.

2. The low frequency tuned liquid column damper according to claim 1, characterized in that: The damping liquid is a mixture of seawater and ethylene glycol, with a density range of 1150-1250 kg / m 3 , freezing point ≤-30℃.

3. The low frequency tuned liquid column damper according to claim 1, characterized in that: The ratio of the curvature radius of the curved section of the horizontal serpentine pipeline and the vertical serpentine pipeline to the pipe diameter is 2.5-3.

0.

4. The low frequency tuned liquid column damper according to claim 1, characterized in that: The aperture ratio of the damping valve can be continuously adjusted between 0% and 80%, and the liquid column damping ratio can be adjusted within a range of 0.03-0.

15.

5. The low frequency tuned liquid column damper according to claim 1, characterized in that: The adjacent first horizontal pipe sections and vertical pipe sections are connected by a circular arc pipe transition with an angle of 90°.

6. A four-buoy semi-submersible floating platform, comprising a central buoy and three peripheral buoys, wherein the three peripheral buoys are evenly distributed in an annular manner relative to the axis of the central buoy; horizontal connecting cylinders located in radial directions are respectively provided between the central buoy and the three peripheral buoys, wherein the horizontal connecting cylinders connect the central buoy with the corresponding peripheral buoys; characterized in that: Also includes a low frequency tuned liquid column damper as described in any one of claims 1 to 5; The three vertical tuning liquid columns are respectively arranged in the three peripheral buoys; The three horizontal tuning liquid columns are respectively arranged in the three horizontal connecting tubes.

7. The four-buoy semi-submersible floating platform according to claim 6 is characterized in that: The first horizontal pipe section and the second horizontal pipe section are fixed to the pipe wall of the horizontal connecting tube through a rigid bracket, and the rigid bracket is made of a double-layer anti-corrosion steel plate, and the surface of the double-layer anti-corrosion steel plate is coated with a polyurethane shock-absorbing layer; The vertical pipe section is fixed to the inner wall of the cabin of the peripheral buoy through a multi-directional articulated flexible connector. The multi-directional articulated flexible connector allows the vertical pipe section to swing in multiple directions within a range of ±3° to adapt to dynamic deformation of the platform.

8. The four-buoy semi-submersible floating platform according to claim 6, characterized in that: The total mass of the low-frequency tuned liquid column damper accounts for 15%-20% of the mass of the ballast water of the four-buoy semi-submersible floating platform.

9. The four-buoy semi-submersible floating platform according to claim 6, characterized in that: A central base located below the horizontal tuning liquid column is provided in the central buoy, a lower support ring for supporting three adjacent second horizontal pipe sections is provided on the central base, and an upper support ring located above the three adjacent second horizontal pipe sections is provided above the lower support ring; the lower support ring and the upper support ring are fixedly connected to the central base by bolts.

10. An offshore wind turbine, comprising a tower, a nacelle and blades, characterized in that: A four-buoy semi-submersible floating platform as described in any one of claims 6 to 9 is provided at the bottom of the tower.

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