Offshore wind turbine floating foundation and offshore floating type wind turbine

Abstract

The invention belongs to the related technical field of vibration control of floating type platform structures, and discloses an offshore wind turbine floating foundation and an offshore floating type wind turbine. The offshore wind turbine floating foundation comprises a floating platform, a damping plate and a tuning liquid column damper, and the tuning liquid column damper is arranged in the floating platform; the multiple damping plates are symmetrically arranged on the floating platform. The damping plate is of a trapezoidal structure and is connected to the floating platform through an elastic rotating shaft, and the damping plate is arranged in the axial direction of the floating platform. The offshore wind turbine floating foundation provided by the invention is relatively good in applicability and has a good vibration reduction effect.

Description

Technical Field

[0001] The present invention belongs to the technical field related to vibration control of floating platform structures, and more specifically, relates to an offshore wind turbine floating foundation and an offshore floating wind turbine. Background Art

[0002] In the field of wind power generation, with the continuous development of wind power technology, offshore wind power will not be able to meet the needs of renewable energy development in the future. With the continuous improvement of theoretical knowledge and the gradual development of construction technology, people have begun to explore deeper and farther seas in order to obtain wind energy resources in a larger sea area. In the future, the development of offshore wind power will inevitably shift from shallow seas to deep seas. Traditional fixed foundations cannot be used because of their high cost and the lack of stability in deep sea environments. The applicable water depth of floating foundations is more than 60m. Therefore, floating foundations will surely become the best choice for deep-sea wind power development in the future.

[0003] However, compared with onshore wind turbines and offshore fixed-pile wind turbines, floating wind turbines have more technical difficulties. First, in the marine environment, they are affected by environmental loads such as wind, waves, and currents. The movement will be mainly the overall rigid displacement of the floating platform and the wind turbine, rather than the vibration inside the wind turbine structure. How to reduce the vibration of the floating platform is a hot topic in the current research of offshore wind power. Second, the action of waves and ocean currents causes the floating platform of the offshore floating wind turbine to produce pitch and roll motion, which leads to large fluctuations in the inflow wind speed of the wind turbine, significantly increasing the aerodynamic load, causing a large simple harmonic vibration response of the generator and the nacelle, causing fatigue damage to the wind turbine structure, reducing the fatigue life of the offshore wind turbine, and having different degrees of impact on the overall output power, power generation and stability of the offshore wind farm.

[0004] At present, in order to reduce the load impact of floating wind turbines and optimize the structural design, it is usually preferred to control the vibration of floating platforms. There are two main methods for vibration control of offshore floating wind turbine platforms: active control and passive control. Considering the complex load environment and multi-directional frequency vibration characteristics of offshore wind turbines, the use of active control technology is time-consuming and labor-intensive, requiring a large number of formula derivations and simulation studies, and has poor applicability in actual engineering. The existing passive control technology uses a single mass and damping coefficient for TMD, which can only control the vibration frequency in a single direction. If the frequency in multiple directions is to be controlled, the number and cost of TMD will increase greatly, which is obviously not applicable to the complex movement of offshore wind turbine floating platforms; at the same time, although TMD utilizes the inertia of the mass block to realize the transfer of energy from the main structure to the damper system, the required mass block is heavy, and the mass block guide system has to bear a large friction force, and the engineering application cost is high. Compared with TMD passive control technology, tuned liquid column damper (TLCD) vibration reduction control system uses a rectangular or U-shaped water tank as an additional damping adjustment device, and uses the damping generated by the movement of the water tank liquid to consume the energy of the unit vibration, thereby achieving the purpose of reducing structural vibration. Its structural bearing form is simple, easy to adjust, and has the advantages of low cost and maintenance, easy to manufacture and install. At the same time, the tubular shape is more suitable for the narrow space of the semi-submersible floating platform of offshore wind turbines, so it is widely used in the field of structural vibration reduction. With the continuous development of offshore wind energy resources, the use of TLCD to economically and effectively control the structural vibration of offshore wind turbines, especially the dynamic response of floating platforms, has become a current research focus.

[0005] In addition, in the current offshore wind turbine field, the research on semi-submersible platform wind turbines is still in the active exploration stage. The semi-submersible floating foundation has a good response to the hydrodynamic characteristics of wind and wave combined load excitation, a relatively stable dynamic response, strong adaptability, low transportation and installation difficulty, flexible adaptation to water depth, relatively mature technology, and good commercial application prospects. However, the innovation and optimization of semi-submersible floating platforms are relatively insufficient. A semi-submersible floating platform with better applicability and good vibration reduction effect is needed to provide a safe and reliable platform support foundation structure for high-power floating offshore wind turbines, ensure their stable operation and life, and promote the innovation and development of offshore wind power. Summary of the invention

[0006] In view of the above defects or improvement needs of the prior art, the present invention provides an offshore wind turbine floating foundation and an offshore floating wind turbine, which aims to provide an offshore wind turbine floating foundation with good applicability and good vibration reduction effect.

[0007] To achieve the above-mentioned purpose, according to one aspect of the present invention, a floating foundation for an offshore wind turbine is provided, wherein the floating foundation for an offshore wind turbine comprises a floating platform, a damping plate and a tuned liquid column damper, wherein the tuned liquid column damper is arranged in the floating platform, and a plurality of the damping plates are symmetrically arranged on the floating platform; the damping plate is a trapezoidal structure, which is connected to the floating platform through an elastic rotating shaft, and the damping plate is arranged along the axial direction of the floating platform.

[0008] Furthermore, the floating platform includes a central column, six base columns, six side columns, a plurality of cross bars and a plurality of diagonal braces. The six base columns are evenly arranged around the central column and are respectively located at the vertices of the same regular hexagon. The six side columns are respectively vertically fixed on the six base columns, and the side columns are coaxially arranged with the corresponding base columns. The plurality of base columns are respectively connected by a plurality of cross bars, the base columns are also connected to the central column by the cross bars, and the side columns are also connected to the central column by the cross bars. The bottom of the central column is respectively connected to the top of the side columns by diagonal braces.

[0009] Furthermore, the base column, the side column, the cross bar and the middle column located on the diagonal of the regular hexagon form a mountain-shaped receiving cavity, and the three tuned liquid column dampers are respectively arranged in the three receiving cavities.

[0010] Furthermore, two of the damping plates are symmetrically mounted on each of the side columns, and two of the damping plates are symmetrically and invertedly mounted on the center column; and the damping plates are plates with non-uniform trapezoidal cross-sections.

[0011] Furthermore, the tuned liquid column damper includes a damping orifice plate, a mountain-shaped basic cavity and a spiral tube, the three spiral tubes are respectively connected to the three ends of the basic cavity, and the three spiral tubes are connected to the basic cavity; the basic cavity is located in the corresponding base column and the cross bar, and the three spiral tubes are respectively located in the corresponding two side columns and the middle column; two damping orifice plates form a group, one group of damping orifice plates is arranged in the basic cavity, and the corresponding two damping orifice plates are spaced apart to form a damping hole.

[0012] Furthermore, the damping orifice plate is connected to the inner wall of the basic cavity, and a threaded hole is opened on one side thereof. One end of the screw passes through the waterproof rubber gasket to form a threaded connection with the threaded hole, and the other end is connected with a nut.

[0013] Furthermore, the damping hole plate is moved up and down by rotating the screw, thereby adjusting the size of the damping hole.

[0014] The present invention also provides an offshore floating wind turbine, which comprises the offshore wind turbine floating foundation and a wind turbine assembly as described above, wherein the wind turbine assembly is connected to the offshore wind turbine floating foundation.

[0015] In general, compared with the prior art, the above technical solutions conceived by the present invention mainly have the following beneficial effects:

[0016] 1. The tuned liquid column damper is arranged in the floating platform, and a plurality of damping plates are symmetrically arranged on the floating platform. The tuned liquid column damper is combined with the trapezoidal damping plate, and eddies and damping are generated under the action of multi-directional wave currents through the mechanical damping plate, so as to quickly respond to high-frequency and small-amplitude vibrations; while TLCD achieves efficient energy dissipation by extending the liquid oscillation path, and has good adaptability to low-frequency and large-amplitude wave vibrations; the synergistic effect of the two not only expands the vibration reduction frequency range and adapts to a variety of vibration modes, but also enhances the anti-resonance ability and adaptability of the system, so that the stability and durability of the platform under extreme sea conditions are significantly improved, and excellent vibration reduction effect is exhibited in complex marine environments.

[0017] 2. The three spiral tubes are respectively connected to the three ends of the basic cavity, and the three spiral tubes are connected to the basic cavity. The main advantage of such a spiral structure is that it significantly extends the flow path of the liquid, so that the oscillation period of the liquid in the pipe is lengthened. Compared with the traditional U-shaped structure, the flow distance of the spiral pipe is longer, which can effectively increase the damping effect in the liquid flow. The longer path means that the liquid column has more time and space to dissipate kinetic energy when vibrating, thereby improving the damping efficiency. This design not only enhances the energy dissipation capacity, but also effectively reduces the vibration amplitude of the platform, so that the platform performs better under low-frequency and large-amplitude vibration conditions.

[0018] 3. The spiral pipe can flexibly adapt to the impact of waves and currents from different directions and is suitable for multi-directional vibration reduction needs. In the traditional U-type TLCD, the liquid can only flow in a single plane, which makes it difficult to cope with multi-directional vibrations. The spiral structure allows the liquid to produce compound motion in all directions with the vibration of the platform. Whether it is lateral, longitudinal or oblique vibration, the liquid in the spiral tube can provide corresponding damping effect. This wide-angle adaptability makes the spiral tubular TLCD more advantageous in complex marine conditions and helps to comprehensively improve the vibration reduction capacity of the floating wind turbine platform.

[0019] 4. The curved path in the spiral structure can form a dynamic fluid pressure distribution under the impact of waves of different frequencies, effectively preventing the system from entering a resonant state. The fixed path of the traditional U-shaped structure is prone to resonance at a specific frequency, and the multi-bending characteristics of the spiral pipe change the natural frequency of the liquid column, making it more difficult for the system to reach a resonant condition. In addition, the fluid pressure distribution in the spiral structure is uneven, and the asymmetric resistance generated further interferes with the formation of resonance. This feature significantly improves the anti-resonance ability of the floating platform at multiple wave frequencies and ensures the stability of the platform.

[0020] 5. The TLCD of the spiral tube produces a flow hysteresis effect during the liquid vibration process, that is, the flow velocity of the liquid column will gradually slow down as the path is extended and bent multiple times. This flow hysteresis allows the liquid column to absorb more kinetic energy under extreme wave and current impact, and slowly recover after the wave action ends. This slow hysteresis effect helps to avoid the platform from vigorous vibration under instantaneous impact, thus having a stronger adaptability to extreme working conditions. Compared with the traditional U-shaped structure, the hysteresis effect of the spiral tube allows the platform to transition smoothly after the wave and current action ends, effectively alleviating the structural stress caused by instantaneous vibration.

[0021] 6. Two damping plates are symmetrically installed on each of the side columns, and two damping plates are symmetrically inverted installed on the middle column; the damping plates are plates with non-uniform trapezoidal cross-sections. Such flow-induced vortex damping plates with non-uniform trapezoidal cross-sections can generate asymmetric vortices under the action of water flow, providing multi-directional adaptive vibration reduction effects. Compared with traditional vibration reduction methods (such as relying on damping materials or passive damping systems in a single direction), the flow-induced vortex damping plate design can adaptively adjust the vortex intensity and distribution in a variety of complex marine environments, and adapt to water flow and wave effects of different directions and frequencies. This multi-directional damping effect is particularly suitable for the complex vibration modes of floating wind turbine platforms under the combined action of wind and waves. By dissipating energy through vortices and dispersing water flow impacts, the platform's translational and rotational amplitudes in all directions are effectively reduced, ensuring that the platform's stability can be maintained even in severe sea conditions.

[0022] 7. Through the non-uniform cross-section design, the vortex generated by the flow-induced vortex damping plate in the water flow can dissipate kinetic energy more efficiently, thereby significantly improving the overall damping effect. Traditional vibration reduction structures usually rely on vibration-absorbing materials or dampers to absorb vibrations, but their energy dissipation method is relatively simple, and it is difficult to adapt to the frequently fluctuating impact force under extreme sea conditions. The flow-induced vortex damping plate uses the vortex generation mechanism of the water flow itself to form a complex and powerful vortex dissipation zone, which converts the kinetic energy of the water into vortex energy and gradually dissipates it. Since the vortex produces a dynamic and asymmetric resistance distribution, this method can more effectively maintain the stability of the vibration reduction effect under high kinetic energy conditions, thereby significantly improving the vibration resistance of the floating platform.

[0023] 8. The flow-induced vortex damping plate is connected to the column through an elastic shaft, which enables the structure to have a higher dynamic response capability in the marine environment. The elastic shaft allows the damping plate to be fine-tuned in angle under the impact of the water flow, realizing dynamic adjustment. Unlike the traditional fixed vibration reduction structure, the flow-induced vortex damping plate can adaptively adjust the damping strength under strong wave currents, and adjust the angle and vortex strength of the damping plate as the water flow changes. Whether it is a change in wave intensity or a change in the direction of the fluid, the damping plate can respond instantly, thereby providing a vibration reduction capability with strong adaptability and fast response speed. This dynamic response characteristic ensures that the platform maintains good vibration reduction performance in complex sea conditions with frequent changes in wind and waves, which is difficult to achieve with traditional vibration reduction structures.

[0024] 9. The flow-induced vortex damping plate is connected by an elastic shaft, which can produce moderate rotation under the action of water flow, thereby effectively dispersing the impact of water flow on the column and auxiliary structures and reducing local stress. At the same time, the formation of vortices can produce a dispersed pressure field around the damping plate, making the water flow more uniform and further reducing stress concentration. Compared with the traditional rigid fixed structure, this design greatly reduces fatigue accumulation and extends the service life of the damping structure, especially in harsh marine environments. It has significant durability advantages.

[0025] 10. By rotating the screw to move the damping hole plate up and down, and then adjusting the size of the damping hole, the difficulty of water flow and the opening size of the damping hole can be freely controlled, so as to conveniently adjust the structural damping of TLCD, which has strong applicability, and the waterproof rubber gasket can avoid water flow loss after opening the hole and maintain the integrity of the TLCD structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a three-dimensional schematic diagram of a floating foundation of an offshore wind turbine provided by the present invention;

[0027] Figure 2 yes Figure 1 Schematic diagram of the structure of the offshore wind turbine floating foundation after removing the mooring components;

[0028] Figure 3 yes Figure 1 Schematic diagram of the structure of the floating foundation of an offshore wind turbine without the flow-induced vortex damping plate;

[0029] Figure 4 (a), (b), (c), and (d) are Figure 1 A three-dimensional schematic diagram and a plan schematic diagram of a damping plate of an offshore wind turbine floating foundation;

[0030] Figure 5 yes Figure 1 A cross-sectional view of the floating foundation of an offshore wind turbine;

[0031] Figure 6 (a) and (b) are Figure 1 Schematic diagram of the principle of TLCD passive vibration reduction of the floating foundation of offshore wind turbines;

[0032] Figure 7 yes Figure 1 Schematic diagram of the damping orifice plate of the offshore wind turbine floating foundation.

[0033] In all the drawings, the same figure numbers are used to represent the same elements or structures, among which: 1-side column, 2-middle column, 3-base column, 4-diagonal brace, 5-cross bar, 6-fairlead hole, 7-damping plate, 8-bifurcation point, 9-mooring line, 10-anchor, 11-elastic rotating shaft, 12-spiral tube, 13-damping orifice plate, 14-tuned liquid column damper, 15-nut, 16-waterproof rubber ring, 17-screw. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0035] The present invention provides an offshore wind turbine floating foundation, which organically combines a tuned liquid column damper 14, a non-uniform trapezoidal cross-section flow-induced vortex damping plate 7 and a semi-submersible floating platform. Based on the semi-submersible floating platform, the platform draft can be reduced by utilizing its displacement volume and overall stability, thereby reducing the degree to which the platform is affected by wave loads and reducing the hydrodynamic load of the platform. At the same time, the bottom of the seven-buoy semi-submersible floating foundation is connected, and TLCD shock absorbers are applied on the three diagonals of the regular hexagon of the platform, thereby fully utilizing the foundation space of each column of the semi-submersible floating platform, relying on the inertial force generated by the movement of liquid in the container and the damping effect caused by the head loss to dissipate energy, reduce the dynamic response of the floating platform, reduce the overall vibration load of the floating platform, and achieve effective vibration reduction control of the offshore floating wind turbine.

[0036] See also Figure 1 , Figure 2 and Figure 3 The present invention provides an offshore wind turbine floating foundation, which includes a floating platform, a damping plate 7 and a tuned liquid column damper 14, wherein the tuned liquid column damper 14 is arranged in the floating platform, and a plurality of damping plates 7 are arranged on the floating platform. The damping plate 7 is a trapezoidal structure, which is connected to the floating platform through an elastic rotating shaft 11, and the damping plate 7 is arranged along the axial direction of the floating platform.

[0037] The floating platform includes a central column 2, six base columns 3, six side columns 1, a plurality of cross bars 5, a plurality of diagonal braces 4, a plurality of anchors 10 and a plurality of mooring lines 9. The six base columns 3 are evenly arranged around the central column 2 and are respectively located at the vertices of the same regular hexagon. The six side columns 1 are respectively vertically fixed on the six base columns 3, and the side columns 1 are coaxially arranged with the corresponding base columns 3. The multiple base columns 3 are respectively connected by a plurality of cross bars 5, the base columns 3 are also connected to the central column 2 by the cross bars 5, and the side columns 1 are also connected to the central column 2 by the cross bars 5. The bottom of the central column 2 is respectively connected to the top of the side column 1 by diagonal braces 4. Among them, the cross bar 5 is a buoy, the buoy and the diagonal brace 4 play a role in force transmission, and the base column 3 plays a role in ballast. The base column 3 is provided with a champere 6, and the mooring line 9 is Y-shaped, with two ends of the mooring line 9 respectively connected to the champeres 6 of two adjacent base columns 3, and the other end connected to the anchor 10. The mooring line 9 is formed with a bifurcation point 8.

[0038] The base column 3, the side column 1, the cross bar 5 and the middle column 2 located on the diagonal of the regular hexagon form a mountain-shaped receiving cavity, and the three tuned liquid column dampers 14 are respectively arranged in the three receiving cavities.

[0039] See also Figure 4 and Figure 5 Two damping plates 7 are symmetrically mounted on each of the side columns 1, and two damping plates 7 are symmetrically and invertedly mounted on the center column 2. The damping plates 7 are plates with non-uniform trapezoidal cross sections.

[0040] Under the combined action of wind and waves at sea, the non-uniform trapezoidal cross-section flow-induced vortex damping plate 7 combined with the elastic shaft 11 plays a significant role in the vibration reduction of the offshore floating wind turbine platform. Its principle is based on the coupling effect of fluid dynamics and structural dynamics. By installing the non-uniform trapezoidal cross-section flow-induced vortex damping plate 7 around the column and connecting it with the elastic shaft 11, the damping plate 7 can produce moderate rotation under the action of waves and currents. First, under the impact of water flow, the flow-induced vortex damping plate 7, due to its trapezoidal cross-section design with unequal upper and lower areas, causes the water flow to produce asymmetric flow separation and vortex structure on both sides of the damping plate 7. The larger lower surface has a larger contact area with the water flow, producing stronger vortices and pressure differences, while the smaller upper surface produces weaker vortex effects. This asymmetric vortex and pressure distribution causes the damping plate 7 to be subjected to unbalanced fluid forces, forming a damping force that acts in the opposite direction on the platform, effectively dissipating the platform's translational kinetic energy and reducing horizontal displacement. At the same time, the introduction of the elastic shaft 11 enables the damping plate 7 to deflect appropriately when impacted by waves and currents, changing the relative angle with the water flow, and optimizing the generation of vortices and the damping effect. When the external force weakens, the restoring force of the elastic shaft 11 returns the damping plate 7 to its initial position to maintain the stability of the system. This design not only enhances the damping capacity of the damping plate 7 against instantaneous impacts, but also improves the energy dissipation efficiency through dynamic adjustment. In addition, when the platform undergoes rotational vibration (such as roll and pitch), the damping plate 7 generates an asymmetric restoring torque under the action of water flow due to its non-uniform trapezoidal cross-section design. The larger lower surface is subjected to a greater hydrodynamic torque, resisting the platform's tendency to rotate and reducing the rotation amplitude. The elastic shaft 11 allows the damping plate 7 to adaptively adjust its angle according to changes in the water flow and platform movement, thereby improving the vibration reduction effect. In summary, the non-uniform trapezoidal cross-section flow-induced vortex damping plate 7 enhances the vortex generation and damping effect through its special geometric design, and the application of the elastic shaft 11 gives the damping plate 7 dynamic response capability, so that it can effectively reduce the translational and rotational vibrations of the platform under the combined action of wind and waves, and improve the stability and durability of the floating wind turbine platform. This vibration reduction mechanism makes full use of the interaction between fluid and structure, and has the characteristics of simple structure, strong adaptability and significant vibration reduction effect, which provides important technical support for the design and optimization of offshore floating wind turbine platforms.

[0041] See also Figure 6 and Figure 7The tuned liquid column damper 14 includes a damping orifice plate 13, a base cavity in a mountain shape and a spiral tube 12. The three spiral tubes 12 are respectively connected to the three ends of the base cavity, and the three spiral tubes 12 are connected to the base cavity. The base cavity is located in the corresponding base column 3 and the cross bar 5, and the three spiral tubes 12 are respectively located in the corresponding two side columns 1 and the middle column 2. Two damping orifice plates 13 form a group, and a group of damping orifice plates 13 is arranged in the base cavity, and the corresponding two damping orifice plates 13 are arranged at intervals to form a damping hole.

[0042] The damping orifice plate 13 is connected to the inner wall of the base cavity, and a threaded hole is opened on one side of the damping orifice plate 13. One end of the screw 17 passes through the waterproof rubber gasket and forms a threaded connection with the threaded hole, and the other end is connected with a nut 15. The damping orifice plate 13 is moved up and down by rotating the screw 17, thereby adjusting the size of the damping orifice.

[0043] Among them, the optimal tuning rate ratio of TLCD is calculated, and the first vibration frequency of the wind turbine on the new floating platform is calculated at the same time, and the various parameter coefficients of TLCD, such as total length, horizontal section length, cross-sectional area, opening ratio, nonlinear head loss coefficient, etc., are adjusted, and the mass ratio and damping ratio of TLCD are adjusted to make its optimal tuning frequency close to or equal to the first vibration frequency of the floating platform, so that the floating platform can dissipate a certain amount of vibration energy through additional friction loss generated by the oscillation of liquid in the tubular structure at the resonant frequency, thereby achieving the maximum vibration reduction effect, wherein the nonlinear head loss coefficient of TLCD mainly depends on the damping hole ratio, that is, the ratio of the opening size to the cross-sectional area of ​​the U-shaped spiral tube 12. At the same time, the damping orifice plate 13 in TLCD can realize the free rotation adjustment of the damping orifice plate 13 in the vertical direction through the interaction of the screw 17 and the nut 15, and the difficulty of water flow and the opening size can be freely controlled, so as to conveniently adjust the structural damping of TLCD, which has strong applicability, and the waterproof rubber gasket can avoid water flow loss after the opening, and keep the integrity of the TLCD structure. Furthermore, a group of TLCDs on each diagonal line intersects on the main column, which can actually form a three-liquid column TLCD model. The entire floating platform vibration reduction system can be equivalent to six traditional TLCD models, which has a better vibration reduction effect and can fully cope with the complex and changeable loads generated by the marine environment. At the same time, each group of TLCD controls the vibration reduction frequency in different directions, which can achieve multi-directional joint vibration control, maximize the vibration reduction effect at a low cost, greatly reduce the construction cost and maintenance costs, and has good practical significance for actual projects.

[0044] In the traditional U-type TLCD, the vibration of the liquid is mainly driven by the vibration frequency of the platform, but the structural rigidity limits the freedom of the liquid, making it difficult to adapt to multiple vibration frequencies. The introduction of the spiral path breaks this limitation, allowing the liquid column to move in multiple directions, and the bending of each spiral segment can increase the inertia effect of the liquid column, thereby changing the natural frequency of the liquid column. Through the nonlinear characteristics of the spiral path, the movement of the liquid column in the spiral tube 12 shows complex coupling characteristics. When the vibration frequency of the platform changes slightly, the vibration of the liquid column will also adjust accordingly. This adaptive frequency coupling mechanism enables the U-shaped spiral tube 12-shaped TLCD to produce a damping effect at different wave frequencies, expanding the operating frequency range of the TLCD, thereby greatly improving the vibration reduction effect.

[0045] In addition, the spiral tube 12 structure increases the nonlinear response characteristics of the system. The traditional U-type TLCD exhibits linear damping during smooth flow, while the spiral structure introduces nonlinear effects at different flow rates through the bending and deformation of the path. This nonlinear effect is particularly prominent when the platform is subjected to impacts of different intensities - when the wind and waves are large, the spiral structure will increase the flow resistance of the liquid column and form a higher damping force, while when the wind and waves are small, the liquid flows smoothly and the damping force is relatively low. This nonlinear damping characteristic allows the spiral TLCD system to flexibly adapt to the needs of different working conditions and achieve a dynamically adjusted vibration reduction effect.

[0046] The side column 1 and the middle column 2 are connected to the damping plate 7 via the elastic shaft 11, which can achieve the following effects:

[0047] ① Multi-directional adaptive vibration reduction effect: The flow-induced vortex damping plate with a non-uniform trapezoidal cross-section can generate asymmetric vortices under the action of water flow, providing a multi-directional adaptive vibration reduction effect. Compared with traditional vibration reduction methods (such as relying on damping materials in a single direction or passive damping systems), the flow-induced vortex damping plate design can adaptively adjust the vortex intensity and distribution in a variety of complex marine environments, and adapt to water flow and wave effects of different directions and frequencies. This multi-directional damping effect is particularly suitable for the complex vibration mode of floating wind turbine platforms under the combined action of wind and waves. By dissipating energy through vortices and dispersing water flow impact, the platform's translational and rotational amplitudes in all directions are effectively reduced, ensuring that the platform can maintain stability even in severe sea conditions.

[0048] ② Efficient energy dissipation and damping capacity: Through the non-uniform cross-section design, the vortex generated by the flow-induced vortex damping plate in the water flow can dissipate kinetic energy more efficiently, thereby significantly improving the overall damping effect. Traditional vibration reduction structures usually rely on vibration-absorbing materials or dampers to absorb vibrations, but their energy dissipation methods are relatively simple, and they are difficult to adapt to the impact force of frequent fluctuations under extreme sea conditions. The flow-induced vortex damping plate uses the vortex generation mechanism of the water flow itself to form a complex and powerful vortex dissipation zone, which converts the kinetic energy of the water into vortex energy and gradually dissipates it. Because the vortex produces a dynamic and asymmetric resistance distribution, this method can more effectively maintain the stability of the vibration reduction effect under high kinetic energy conditions, thereby significantly improving the vibration resistance of the floating platform.

[0049] ③ Dynamic response adjustment and adaptation to changes in sea conditions: The flow-induced vortex damping plate is connected to the column through an elastic shaft 11, which enables the structure to have higher dynamic response capabilities in the marine environment. The elastic shaft 11 allows the damping plate 7 to fine-tune its angle under the impact of the water flow, thereby achieving dynamic adjustment. Unlike traditional fixed vibration reduction structures, the flow-induced vortex damping plate can adaptively adjust the damping strength under strong wave currents, and adjust the angle and vortex strength of the damping plate 7 as the water flow changes. Whether it is a change in wave intensity or a change in the direction of the fluid, the damping plate 7 can respond instantly, thereby providing a vibration reduction capability with strong adaptability and fast response speed. This dynamic response characteristic ensures that the platform maintains good vibration reduction performance in complex sea conditions with frequent changes in wind and waves, which is difficult to achieve with traditional vibration reduction structures.

[0050] ④ Reduce stress concentration and enhance structural durability: Traditional vibration reduction schemes often cause stress concentration in specific parts of the structure under extreme wave and current impacts, leading to fatigue damage or structural damage. The flow-induced vortex damping plate is connected by an elastic shaft 11, which can produce moderate rotation under the action of water flow, thereby effectively dispersing the impact force of water flow on the columns and auxiliary structures and reducing local stress. At the same time, the formation of vortices can produce a dispersed pressure field around the damping plate 7, making the water flow more uniform and further reducing stress concentration. Compared with traditional rigid fixed structures, this design greatly reduces fatigue accumulation and extends the service life of the damping structure, especially in harsh marine environments. It has significant durability advantages.

[0051] The tuned liquid column damper 14 can achieve the following effects:

[0052] ① Increase the length of the liquid path to achieve higher damping efficiency: The main advantage of the spiral structure is that it significantly extends the flow path of the liquid, which lengthens the oscillation period of the liquid in the pipe. Compared with the traditional U-shaped structure, the flow distance of the spiral tube 12 is longer, which can effectively increase the damping effect in the liquid flow. The longer path means that the liquid column has more time and space to dissipate kinetic energy when vibrating, thereby improving the damping efficiency. This design not only enhances the energy dissipation capacity, but also effectively reduces the vibration amplitude of the platform, allowing the platform to perform better under low-frequency and large-amplitude vibration conditions.

[0053] ② Adapt to multi-directional vibrations and achieve wide-angle vibration reduction: The 12-channel design of the spiral tube can flexibly adapt to wave and current impacts from different directions, and is suitable for multi-directional vibration reduction needs. In traditional U-type TLCDs, the liquid can only flow in a single plane, making it difficult to cope with multi-directional vibrations. The spiral structure allows the liquid to produce compound motion in all directions as the platform vibrates. Whether it is lateral, longitudinal or oblique vibration, the liquid in the spiral tube 12 can provide the corresponding damping effect. This wide-angle adaptability makes the spiral tube 12-shaped TLCD more advantageous in complex marine conditions, and helps to comprehensively improve the vibration reduction capacity of floating wind turbine platforms.

[0054] ③ Dynamic fluid pressure distribution, enhancing the system's anti-resonance ability: The curved path in the spiral structure can form a dynamic fluid pressure distribution under the impact of waves of different frequencies, effectively preventing the system from entering a resonant state. The fixed path of the traditional U-shaped structure is prone to resonance at a specific frequency, and the multi-bending characteristics of the 12 spiral tubes change the natural frequency of the liquid column, making it more difficult for the system to reach resonance conditions. In addition, the fluid pressure distribution in the spiral structure is uneven, and the asymmetric resistance generated further interferes with the formation of resonance. This feature significantly improves the anti-resonance ability of the floating platform at a variety of wave frequencies, ensuring the stability of the platform.

[0055] ④ Provide flow hysteresis effect to alleviate extreme wave and current impact: The spiral tube 12-shaped TLCD produces a flow hysteresis effect during the liquid vibration process, that is, the flow velocity of the liquid column will gradually slow down as the path is extended and bent multiple times. This flow hysteresis allows the liquid column to absorb more kinetic energy under extreme wave and current impact, and slowly recover after the wave action ends. This slow hysteresis effect helps to avoid violent vibration of the platform under instantaneous impact, thereby having a stronger adaptability to extreme working conditions. Compared with the traditional U-shaped structure, the hysteresis effect of the spiral tube 12 allows the platform to transition smoothly after the wave and current action ends, effectively alleviating the structural stress caused by instantaneous vibration.

[0056] In addition, the mechanical device is a non-uniform trapezoidal cross-section flow-induced vortex damping plate 7 together with an elastic shaft 11 device, and the liquid column tuning device is a tuned liquid column damper 14. The mechanical-liquid column tuning composite damping device combines the advantages of the flow-induced mechanical damping plate 7 and the U-shaped spiral tube 12-shaped liquid column tuned damper (TLCD), providing a wide spectrum of vibration reduction effects under various sea conditions. Compared with the traditional single vibration reduction system, the composite device generates vortices and damping under the action of multi-directional wave currents through the mechanical damping plate 7, and quickly responds to high-frequency, small-amplitude vibrations; while the spiral tube 12-shaped TLCD extends the liquid oscillation path to achieve efficient energy dissipation, and has good adaptability to low-frequency, large-amplitude wave vibrations. The synergistic effect of the two not only expands the vibration reduction frequency range and adapts to various vibration modes, but also enhances the system's anti-resonance ability and adaptability, so that the stability and durability of the platform in extreme sea conditions are significantly improved. This composite device shows excellent vibration reduction effect in complex marine environments and is an effective upgrade of the traditional single vibration reduction structure.

[0057] The present invention also provides an offshore floating wind turbine, which comprises the offshore wind turbine floating foundation and a wind turbine assembly as described above, wherein the wind turbine assembly is connected to the offshore wind turbine floating foundation.

[0058] It will be easily understood by those skilled in the art that 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 and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An offshore wind turbine floating foundation, characterized in that: The offshore wind turbine floating foundation includes a floating platform, a damping plate and a tuned liquid column damper. The tuned liquid column damper is arranged in the floating platform, and a plurality of damping plates are symmetrically arranged on the floating platform. The damping plate is a trapezoidal structure, which is connected to the floating platform through an elastic rotating shaft, and the damping plate is arranged along the axial direction of the floating platform.

2. The offshore wind turbine floating foundation according to claim 1, characterized in that: The floating platform includes a central column, six base columns, six side columns, a plurality of cross bars and a plurality of diagonal braces. The six base columns are evenly arranged around the central column and are respectively located at the vertices of the same regular hexagon. The six side columns are respectively vertically fixed on the six base columns, and the side columns are coaxially arranged with the corresponding base columns. The multiple base columns are respectively connected by a plurality of cross bars, the base columns are also connected to the central column by the cross bars, and the side columns are also connected to the central column by the cross bars. The bottom of the central column is respectively connected to the top of the side columns by diagonal braces.

3. The offshore wind turbine floating foundation according to claim 2, characterized in that: The base column, the side column, the cross bar and the middle column located on the diagonal of the regular hexagon form a mountain-shaped receiving cavity, and the three tuned liquid column dampers are respectively arranged in the three receiving cavities.

4. The offshore wind turbine floating foundation according to claim 2, characterized in that: Two damping plates are symmetrically mounted on each of the side columns, and two damping plates are symmetrically and invertedly mounted on the center column; the damping plates are plates with non-uniform trapezoidal cross-sections.

5. The offshore wind turbine floating foundation according to claim 2, characterized in that: The tuned liquid column damper includes a damping orifice plate, a mountain-shaped basic cavity and a spiral tube, wherein the three spiral tubes are respectively connected to the three ends of the basic cavity, and the three spiral tubes are communicated with the basic cavity; the basic cavity is located in the corresponding base column and the cross bar, and the three spiral tubes are respectively located in the corresponding two side columns and the middle column; two damping orifice plates form a group, one group of damping orifice plates is arranged in the basic cavity, and the corresponding two damping orifice plates are arranged at intervals to form a damping hole.

6. The offshore wind turbine floating foundation according to claim 5, characterized in that: The damping orifice plate is connected to the inner wall of the basic cavity, and a threaded hole is opened on one side of the damping orifice plate. One end of the screw passes through the waterproof rubber gasket to form a threaded connection with the threaded hole, and the other end is connected with a nut.

7. The offshore wind turbine floating foundation according to claim 6, characterized in that: The damping hole plate is moved up and down by rotating the screw, thereby adjusting the size of the damping hole.

8. An offshore floating wind turbine, characterized in that: The offshore floating wind turbine comprises the offshore wind turbine floating foundation and a wind turbine assembly as described in any one of claims 1 to 7, and the wind turbine assembly is connected to the offshore wind turbine floating foundation.

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