Multi-degree-of-freedom nonlinear energy trap damping device applied to offshore floating fan

Abstract

The invention discloses a multi-degree-of-freedom nonlinear energy trap damping device applied to an offshore floating fan. The multi-degree-of-freedom nonlinear energy trap damping device comprises a floating platform, a tower drum and a wind generating set, the floating type platform comprises three buoys which are arranged in an equilateral triangle mode, and the buoys are fixed to one another. Each buoy is provided with a nonlinear energy trap and a cylindrical stand column arranged outside the nonlinear energy trap in a sleeving mode. The nonlinear energy trap comprises a spherical grooved wheel track and a spherical mass block placed in the spherical grooved wheel track, the spherical grooved wheel track is fixed to the top of a supporting rod, and the bottom of the supporting rod is fixed to a buoy through a support; four annular buckles which are evenly distributed in a circumferential array mode are welded to the surface of the spherical mass block, four non-linear springs which are distributed in a circumferential array mode are evenly distributed on the periphery of the spherical grooved wheel track, and each non-linear spring is connected with the corresponding annular buckle. According to the invention, the six-degree-of-freedom motion response of the floating type wind turbine under the excitation of an external environment can be effectively reduced.

Description

Technical Field

[0001] The invention belongs to the field of offshore wind power, and in particular relates to a multi-degree-of-freedom nonlinear energy sink vibration reduction device applied to an offshore floating wind turbine. Background Art

[0002] Floating wind turbines mainly include floating structures and wind turbines. In the marine environment, floating wind turbines are stimulated by external environments such as wind, waves and ocean currents, and are prone to additional six-degree-of-freedom motions, including pitch, roll, bow pitch, surge, sway and heave.

[0003] A Chinese patent document with publication number CN118618551A discloses a floating foundation for a semi-submersible floating offshore wind turbine and its application in an offshore wind turbine, including a column, a bottom buoy and a connecting buoy. The connecting buoy is connected to the bottom surface of the column, and the bottom surface of the column is transitionally connected to the first end of the bottom buoy arranged in a horizontal plane parallel to the axis in a non-vertical connection manner.

[0004] The Chinese patent document with publication number CN104401458A discloses a semi-submersible floating wind turbine foundation and a floating wind turbine, comprising: at least three columns; a column connection structure, connected to the lower end of each column respectively, so that the column and the column connection structure form an integral body; a support column, arranged in the center of the floating wind turbine foundation, used to support the tower, nacelle, blades and wind turbine generator set of the wind turbine, wherein the cross-sectional area of ​​each column increases upward at a predetermined position below the water surface. The floating wind turbine comprises: the semi-submersible floating wind turbine foundation; a tower, mounted on the support column of the semi-submersible floating wind turbine foundation; a nacelle, mounted on the top of the tower; and a wind turbine generator set and blades, mounted at the front end of the nacelle.

[0005] However, conventional floating wind turbine vibration control methods generally have difficulty in suppressing multi-degree-of-freedom motions simultaneously, and the effectiveness of linear passive vibration dampers only works within a narrow frequency range. Summary of the invention

[0006] The present invention provides a multi-degree-of-freedom nonlinear energy well vibration reduction device applied to an offshore floating wind turbine, which can realize wide-band, multi-degree-of-freedom direction vibration control and can effectively reduce the six-degree-of-freedom motion response of the floating wind turbine under external environmental excitation.

[0007] A multi-degree-of-freedom nonlinear energy sink vibration reduction device applied to an offshore floating wind turbine comprises a floating platform, a tower fixed on the floating platform, and a wind turbine generator set installed on the top of the tower;

[0008] The floating platform comprises three buoys arranged in an equilateral triangle, and the buoys are fixed to each other; each buoy is provided with a nonlinear energy well and a cylindrical column sleeved outside the nonlinear energy well;

[0009] The nonlinear energy sink comprises a spherical groove wheel track and a spherical mass block placed in the spherical groove wheel track, the spherical groove wheel track is fixed on the top of the support rod, and the bottom of the support rod is fixed on the buoy through a support;

[0010] The surface of the spherical mass block is welded with four annular buckles evenly distributed in a circumferential array, and four nonlinear springs evenly distributed in a circumferential array are distributed around the spherical groove wheel track, and each nonlinear spring is connected to a corresponding annular buckle.

[0011] The material of the spherical mass block can be a high-density, lightweight composite material, which can not only ensure the quality, but also reduce the volume of the sphere, and reduce the difficulty of installation and maintenance of the entire system. The nonlinear characteristics of the nonlinear spring make it show different stiffness under different motion amplitudes.

[0012] Furthermore, the cylindrical columns, the cylindrical columns and the tower, and the buoy and the tower are all fixed to each other.

[0013] Furthermore, a sliding mass block and a spring are sleeved on the support rod; the lower end of the spring is fixed to the support, and the upper end is fixed to the sliding mass block, and the sliding mass block can slide up and down along the support rod. The spring is designed as a linear spring with appropriate stiffness, which can provide restoring force under different displacements.

[0014] Furthermore, four fixing members for connecting the nonlinear springs are evenly arranged along the circumference of the inner wall of the cylindrical column.

[0015] Furthermore, four arc-shaped openings are evenly arranged on the spherical groove wheel track, and each nonlinear spring passes through the corresponding arc-shaped opening.

[0016] Furthermore, the support rod is a segmented telescopic structure, composed of a plurality of concentrically nested cylinders, and each segment is connected by a mechanical locking mechanism and a driving device. When the length needs to be adjusted, the driving device can push or pull back the embedded rod segment to change the overall length. The outer layer of the support rod is a main tube with strong rigidity, and the inside is a plurality of nested small tubes (or multiple coaxial cylinders). The fit between the outer tube and the inner tube needs to be designed with high precision to ensure that there is no shaking during the adjustment process. A rubber pad is installed on the top of the support rod to avoid impact or vibration caused by sudden length adjustment.

[0017] Furthermore, a plurality of acceleration sensors and displacement sensors are provided on the floating platform to monitor the motion state of the floating platform in real time; data from the acceleration sensors and displacement sensors are transmitted to a central control unit, and the frequency and amplitude of the motion are analyzed through an algorithm to predict the optimal support rod length as the target length; the actuator controls the driving device, and after driving the support rod to the target length, the mechanical locking mechanism fixes it, thereby realizing dynamic adjustment of the length of the support rod.

[0018] Preferably, the total mass of the three nonlinear energy sinks is 2% to 10% of the total mass of the structure to be damped, and the structure to be damped includes a floating platform, a tower and a wind turbine generator set.

[0019] Furthermore, when installing the nonlinear energy sink, part of the ballast mass of the floating platform is replaced by the mass of the nonlinear energy sink, so that the center of gravity and the overall mass of the offshore floating wind turbine remain unchanged.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention installs a nonlinear energy sink device on each floating platform. When the floating platform is stimulated by the external environment to produce multi-degree-of-freedom motion, the spherical mass block will produce corresponding displacement with the movement of the platform, and the kinetic energy of the spherical mass block will be converted into elastic energy through the stretching and compression of the nonlinear spring. These nonlinear springs provide a softer resistance in the early stage of movement, so that small vibrations are effectively absorbed and not transmitted to the platform itself. As the displacement increases, the spring stiffness gradually increases, so that the system can still maintain stability under large-amplitude vibrations. At this time, the spring further absorbs the vibration energy through the nonlinear restoring force. At the same time, during the compression and extension of the spring, due to the internal friction and damping effect of the material, part of the energy is dissipated, thereby effectively suppressing the motion response of the platform and improving the stability of the platform in complex sea conditions.

[0022] 2. The present invention arranges a sliding mass block and a spring on the support rod. When the floating platform generates a heave response, the sliding mass block will reciprocate up and down along the support rod under the action of the spring. The sliding mass block moves downward along the support rod under the action of inertia. At this time, the spring is compressed to store elastic potential energy. The restoring force of the spring pushes the sliding mass block to move upward in the opposite direction, exerting a reaction force on the platform to offset part of the heave energy of the platform. Thus, the heave response of the floating platform is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The present invention is a schematic diagram of the overall structure of a multi-degree-of-freedom nonlinear energy sink vibration reduction device applied to an offshore floating wind turbine.

[0024] Figure 2 Schematic diagram of the nonlinear energy well in the present invention.

[0025] Figure 3 It is a three-dimensional structural diagram of the nonlinear energy well in the present invention.

[0026] Figure 4 It is a schematic diagram of the layout of the nonlinear energy well device in the present invention.

[0027] Among them: 1. wind turbine generator set, 2. tower, 3. floating platform, 401. nonlinear energy well No. 1, 402. nonlinear energy well No. 2, 403. nonlinear energy well No. 3, 41. spherical groove wheel track, 42. spherical mass block, 43. nonlinear spring, 44. ring buckle, 45. support rod, 46. sliding mass block, 47. spring, 48. support, 5. fixing part, 6. buoy, 7. cylindrical column. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be pointed out that the embodiments described below are intended to facilitate the understanding of the present invention and do not have any limiting effect on the present invention.

[0029] like Figures 1 to 4 As shown, a multi-degree-of-freedom nonlinear energy sink vibration reduction device applied to an offshore floating wind turbine includes a floating platform 3, a tower 2 fixed on the floating platform 3, and a wind turbine generator set 1 installed on the upper part of the tower 2.

[0030] The floating platform 3 includes three pontoons 6 arranged in an equilateral triangle. Each pontoon 6 is provided with a nonlinear energy well, specifically, nonlinear energy well No. 1 401, nonlinear energy well No. 2 402 and nonlinear energy well No. 3 403. Each nonlinear energy well is provided with a cylindrical column 7 on the outside.

[0031] In order to increase the stability of the entire structure, the buoys 6, the cylindrical columns 7, the cylindrical columns 7 and the tower 2, and the buoys 6 and the tower 2 are all fixed to each other by connecting rods.

[0032] like Figure 2 and Figure 3 As shown, the nonlinear energy sink includes a spherical sheave track 41 and a spherical mass block 42 placed in the spherical sheave track 41. The spherical sheave track 41 is fixed to the top of a support rod 45, and the bottom of the support rod 45 is fixed to the buoy 6 through a support 48.

[0033] Four annular buckles 44 evenly distributed in a circular array are welded to the surface of the spherical mass block 42 , and four nonlinear springs 43 evenly distributed in a circular array are distributed around the spherical groove wheel track 41 , and each nonlinear spring 43 is connected to a corresponding annular buckle 44 .

[0034] The support rod 45 is sleeved with a sliding mass block 46 and a spring 47 ; the lower end of the spring 47 is fixed to the support 48 , and the upper end is fixed to the sliding mass block 46 , and the sliding mass block 46 can slide up and down along the support rod 45 .

[0035] like Figure 3 and Figure 4 As shown, four fixing members 5 for connecting the nonlinear springs 43 are evenly arranged along the circumference of the inner wall of the cylindrical column 7. Four arc-shaped openings are evenly arranged on the spherical groove wheel track 41, and each nonlinear spring 43 passes through the corresponding arc-shaped opening.

[0036] The support rod 45 is a segmented telescopic structure, consisting of a plurality of concentrically nested cylinders, and each segment is connected by a mechanical locking mechanism and a driving device.

[0037] In the embodiment of the present invention, the total mass of the nonlinear energy sink device is 2% to 10% of the mass of the structure to be damped.

[0038] When the wind turbine is stimulated by the external environment, the platform generates six degrees of freedom movement, and the spherical mass block 42 moves along the spherical groove wheel track 41. Due to the spherical design of the track, the movement trajectory of the spherical mass block 42 has multi-degree-of-freedom characteristics and can move in different directions. Since the platform will move in different directions at the same time, the spherical mass block 42 can follow the multi-degree-of-freedom changes of the platform movement on the track, thereby generating corresponding displacement and reaction force. For example: when the platform pitches or rolls, the spherical mass block 42 will move along the front and back or left and right directions of the spherical track; when the platform pitches, the spherical mass block 42 will move along an arc trajectory around the center of the platform; when the platform swings longitudinally and laterally, the spherical mass block will also make corresponding displacements according to these translational motion directions.

[0039] The movement of the spherical mass block 42 is constrained and regulated by four nonlinear springs 43 distributed in a circular array. These nonlinear springs 43 are evenly distributed around the track and connected to the spherical mass block 42 to ensure that the springs provide restoring force when the mass block is displaced. Due to the circular distribution design, the nonlinear springs 43 can act on the mass block from multiple directions at the same time, thereby balancing the movement of the mass block and providing multi-directional nonlinear restoring force. When the platform movement causes the spherical mass block to move in a certain direction along the spherical track, the nonlinear spring 43 in that direction is stretched or compressed to generate a restoring force; at the same time, the nonlinear springs 43 in other directions will also respond passively according to their positions to ensure the balance of the restoring force.

[0040] Since the nonlinear springs 43 are evenly distributed on the circumference, no matter in which direction the platform moves, the spring system can ensure that it responds effectively to vibrations in different directions. The movement of the mass block is affected by the interaction of four nonlinear springs 43 distributed in a circular array. The nonlinear characteristics of the springs make them exhibit different stiffnesses at different movement amplitudes. These nonlinear springs 43 have highly nonlinear mechanical properties. Its stiffness is not fixed, but changes dynamically according to the amplitude of the displacement of the spherical mass block 42: when the platform produces a small amplitude vibration or displacement, the stiffness of the nonlinear spring 43 is lower. This means that the movement of the mass block will be subject to a smaller restoring force, making the system respond more gently at small amplitudes. This feature is conducive to absorbing and dissipating small amplitude vibration energy, preventing the system from being overly sensitive to small disturbances, and maintaining the smooth operation of the platform.

[0041] When the platform is subjected to a large external excitation (such as large waves or strong winds) causing a large displacement, the stiffness of the nonlinear spring 43 will increase significantly. At this time, the spring system can quickly provide a large restoring force to prevent the mass block from excessive displacement, thereby effectively absorbing and dissipating high-amplitude vibration energy. This amplitude-dependent stiffness change ensures that the system can still provide sufficient damping effect when responding to large vibrations, avoiding violent responses of the platform when subjected to large-amplitude vibrations. This can effectively absorb and dissipate the vibration energy of the platform, thereby reducing the pitch, roll, bow pitch, surge and sway responses of the platform.

[0042] At the same time, when the floating platform 3 generates a heaving response, the sliding mass block 46 will reciprocate up and down along the support rod 45 under the action of the spring 47, and the sliding mass block will move downward along the support rod under the action of inertia. At this time, the compression spring stores elastic potential energy. The restoring force of the spring pushes the sliding mass block to move in the opposite direction upward. A reaction force is applied to the platform to offset part of the heaving energy of the platform, thereby reducing the heaving response of the floating platform 3. According to different sea conditions, the length of the support rod 45 is changed to adapt to different heaving frequencies. Combined with sensors and actuators, the length of the support rod 45 is dynamically adjusted by real-time monitoring of the movement state of the wind turbine platform. Such an active control system can further improve the absorption efficiency of vibration energy, especially in complex marine environments, and significantly improve the vibration reduction effect.

[0043] The adjustable support rod includes a mechanical locking device: a mechanical locking device is provided between each section, usually using a buckle or bolt locking method. When the support rod reaches the target length, the automatic locking mechanism fixes it.

[0044] Hydraulic or electric drive system: The length of the support rod can be controlled by a hydraulic cylinder or electric push rod system. The hydraulic cylinder can extend or retract the support rod by applying hydraulic pressure, while the electric push rod can adjust the length by driving the motor.

[0045] Sensors: Multiple acceleration sensors and displacement sensors are installed on the platform to monitor the motion state of the platform in real time, especially the amplitude and frequency of the heaving swing.

[0046] Control system: Sensor data is transmitted to the central control unit, which uses an algorithm to analyze the frequency and amplitude of the movement and predict the optimal support rod length.

[0047] Actuator: The control unit sends a signal to automatically adjust the length of the support rod through the hydraulic or electric drive system to achieve adaptive adjustment.

[0048] Long-period identification algorithm: The control system introduces a long-period wave detection algorithm to monitor the changing trend of sea conditions and identify the heave frequency in special environments such as huge waves in advance.

[0049] Pre-adjustment function: When the system detects long-period sea conditions, the support rod will be adjusted in length in advance so that it is already in the best condition when the sea conditions deteriorate, avoiding delayed response.

[0050] The present invention can effectively reduce the six-degree-of-freedom motion response of a floating wind turbine under external environmental excitation. The nonlinear characteristics of the system design realize effective control of different vibration amplitudes and directions, significantly increase the vibration reduction frequency band, and achieve broadband vibration absorption. This innovative vibration control method greatly improves the stability and operational reliability of floating wind turbines, extends the service life of wind turbines, and has important practical value and broad application prospects.

[0051] The embodiments described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A multi-degree-of-freedom nonlinear energy sink vibration reduction device applied to an offshore floating wind turbine, characterized in that: It comprises a floating platform (3), a tower (2) fixed on the floating platform (3), and a wind turbine generator set (1) installed on the upper part of the tower (2); The floating platform (3) comprises three buoys (6) arranged in an equilateral triangle, and the buoys (6) are fixed to each other; each buoy (6) is provided with a nonlinear energy well and a cylindrical column (7) sleeved on the outside of the nonlinear energy well; The nonlinear energy sink comprises a spherical sheave track (41) and a spherical mass block (42) placed in the spherical sheave track (41), the spherical sheave track (41) is fixed to the top of a support rod (45), and the bottom of the support rod (45) is fixed to a buoy (6) via a support (48); Four annular buckles (44) evenly distributed in a circumferential array are welded on the surface of the spherical mass block (42), four nonlinear springs (43) evenly distributed in a circumferential array are evenly distributed around the spherical groove wheel track (41), and each nonlinear spring (43) is connected to a corresponding annular buckle (44).

2. The multi-degree-of-freedom nonlinear energy sink vibration reduction device for offshore floating wind turbines according to claim 1 is characterized in that: The support rod (45) is sleeved with a sliding mass block (46) and a spring (47); the lower end of the spring (47) is fixed to a support (48), and the upper end is fixed to the sliding mass block (46); the sliding mass block (46) can slide up and down along the support rod (45).

3. The multi-degree-of-freedom nonlinear energy sink vibration reduction device for offshore floating wind turbines according to claim 1 is characterized in that: Four fixing members (5) for connecting nonlinear springs (43) are evenly arranged along the circumference of the inner wall of the cylindrical column (7).

4. The multi-degree-of-freedom nonlinear energy sink vibration reduction device for offshore floating wind turbines according to claim 3 is characterized in that: The spherical groove wheel track (41) is evenly provided with four arc-shaped openings, and each nonlinear spring (43) passes through a corresponding arc-shaped opening.

5. The multi-degree-of-freedom nonlinear energy sink vibration reduction device for offshore floating wind turbines according to claim 1, characterized in that: The support rod (45) is a segmented telescopic structure, consisting of a plurality of concentrically nested cylinders, and each segment is connected by a mechanical locking mechanism and a driving device.

6. The multi-degree-of-freedom nonlinear energy sink vibration reduction device for offshore floating wind turbines according to claim 5, characterized in that: A plurality of acceleration sensors and displacement sensors are arranged on the floating platform (3) to monitor the motion state of the floating platform (3) in real time; Data from the acceleration sensor and the displacement sensor are transmitted to a central control unit, which analyzes the frequency and amplitude of the movement through an algorithm and predicts the optimal length of the support rod (45) as a target length; the actuator controls the driving device, and after driving the support rod (45) to the target length, the mechanical locking mechanism fixes it, thereby dynamically adjusting the length of the support rod (45).

7. The multi-degree-of-freedom nonlinear energy sink vibration reduction device for offshore floating wind turbines according to claim 1, characterized in that: The total mass of the three nonlinear energy sinks is 2% to 10% of the total mass of the structure to be reduced in vibration, and the structure to be reduced in vibration comprises a floating platform (3), a tower (2) and a wind turbine generator set (1).

8. The multi-degree-of-freedom nonlinear energy sink vibration reduction device for offshore floating wind turbines according to claim 1, characterized in that: When the nonlinear energy sink is installed, part of the ballast mass of the floating platform (3) is replaced by the mass of the nonlinear energy sink, so that the center of gravity and the overall mass of the offshore floating wind turbine remain unchanged.

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