A multi-degree-of-freedom nonlinear energy sink damping device applied to an offshore floating wind turbine

Abstract

The application discloses a kind of multi-degree-of-freedom nonlinear energy sink vibration reduction devices applied to offshore floating wind turbine, including floating platform, tower drum and wind turbine unit;Floating platform includes three equilateral triangle arrangement of pontoon, pontoon is mutually fixed between;Each pontoon is equipped with a nonlinear energy sink and the cylindrical column of nonlinear energy sink outside set;Nonlinear energy sink includes spherical groove wheel track and the spherical mass block placed in spherical groove wheel track, the spherical groove wheel track is fixed in the top of support rod, the bottom of support rod is fixed on pontoon by support;The surface of spherical mass block is welded with four annular buckles that are evenly distributed in circumferential array, four nonlinear springs that are evenly distributed in circumferential array are uniformly distributed around spherical groove wheel track, and each nonlinear spring is connected with corresponding annular buckle.The application can effectively reduce six-degree-of-freedom motion response of floating wind turbine under external environmental excitation.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of offshore wind power, and particularly relates to a multi-degree-of-freedom nonlinear energy sink damping device applied to an offshore floating wind turbine. BACKGROUND

[0002] The floating wind turbine mainly comprises a floating structure and a wind turbine generator set. The floating wind turbine is subjected to external environmental excitations such as wind, wave and ocean current in the marine environment, and is prone to additional six-degree-of-freedom motion, including pitch, roll, yaw, surge, sway and heave.

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

[0004] The Chinese patent document with the publication number CN104401458A discloses a semi-submersible floating wind turbine foundation and a floating wind turbine, which comprises at least three columns, a column connecting structure connected with the lower end of each column to form an integral body with the column, and a support column arranged in the center of the floating wind turbine foundation for supporting the tower, cabin, blade 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 installed on the support column of the semi-submersible floating wind turbine foundation, a cabin installed at the top end of the tower, and a wind turbine generator set and a blade installed at the front end of the cabin.

[0005] However, the conventional floating wind turbine is generally difficult to simultaneously suppress multi-degree-of-freedom motion by using the conventional vibration control method, and the effectiveness of the linear passive damper only works in a relatively narrow frequency range. SUMMARY

[0006] The application provides a multi-degree-of-freedom nonlinear energy sink damping device applied to an offshore floating wind turbine, which can realize wideband and multi-degree-of-freedom vibration control, and 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 damping device applied to an offshore floating wind turbine, which comprises a floating platform, a tower installed on the floating platform, and a wind turbine generator set installed on the upper part of the tower.

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

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

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

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

[0012] Further, the cylindrical columns, the cylindrical columns and the tower columns, and the floating buoys and the tower columns are fixed to each other.

[0013] Further, a sliding mass 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, and the sliding mass 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] Further, the inner wall of the cylindrical column is uniformly provided with four fixing members for connecting the nonlinear springs along the circumference.

[0015] Further, the spherical groove track is uniformly provided with four arc-shaped openings, and each nonlinear spring passes through a corresponding arc-shaped opening.

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

[0017] Further, the floating platform is provided with a plurality of acceleration sensors and displacement sensors for monitoring the motion state of the floating platform in real time; the data of the acceleration sensors and displacement sensors are transmitted to the central control unit, the frequency and amplitude of the motion are analyzed by algorithm, and the optimal support rod length is predicted as the target length; the driving device is controlled by the actuator, and after the support rod is driven to the target length, the mechanical locking mechanism fixes the support rod, so that the length of the support rod is dynamically adjusted.

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

[0019] Further, when the non-linear energy sink is installed, part of the ballast mass of the floating platform is replaced by the mass of the non-linear 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 application has the following beneficial effects:

[0021] 1. By installing the non-linear energy sink device on each floating platform, when the floating platform is subjected to external environmental excitation to produce multi-degree-of-freedom motion, the spherical mass will move with the platform to generate corresponding displacement, and the kinetic energy of the spherical mass is converted into elastic energy through the stretching and compression of the non-linear spring. These non-linear springs provide a relatively soft resistance at the initial stage of motion, so that small amplitude 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 vibration. At this time, the spring further absorbs vibration energy through the non-linear restoring force, and at the same time, 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 state environment.

[0022] 2. By providing a sliding mass and a spring on the support rod, when the floating platform produces heave response, the sliding mass will reciprocate up and down along the support rod under the action of the spring. The sliding mass moves downward along the support rod under the action of inertia, and at this time the spring is compressed to store elastic potential energy. The restoring force of the spring pushes the sliding mass to move upward in the opposite direction, and applies a counterforce to the platform to offset part of the heave energy of the platform, thereby reducing the heave response of the floating platform. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a whole structure schematic diagram of the multi-degree-of-freedom non-linear energy sink damping device applied to the offshore floating wind turbine of the present application.

[0024] Figure 2 It is a schematic diagram of the non-linear energy sink in the present application.

[0025] Figure 3 A perspective view of a non-linear energy sink in the present application.

[0026] Figure 4 A layout view of a non-linear energy sink device in the present application.

[0027] Wherein: 1, wind turbine generator set, 2, tower drum, 3, floating platform, 401, No. 1 non-linear energy sink, 402, No. 2 non-linear energy sink, 403, No. 3 non-linear energy sink, 41, spherical groove track, 42, spherical mass block, 43, non-linear spring, 44, annular buckle, 45, support rod, 46, sliding mass block, 47, spring, 48, support, 5, fixing piece, 6, buoy, 7, cylindrical column. DETAILED DESCRIPTION

[0028] The present application will be further described in detail below in conjunction with the drawings and examples, it should be pointed out that the following examples are intended to facilitate the understanding of the present application, and do not have any limiting effect on it.

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

[0030] The floating platform 3 comprises three buoys 6 arranged in an equilateral triangle, and each buoy 6 is provided with a non-linear energy sink, specifically No. 1 non-linear energy sink 401, No. 2 non-linear energy sink 402 and No. 3 non-linear energy sink 403, and each non-linear energy sink is externally sleeved with a cylindrical column 7.

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

[0032] As shown in Figure 2 and Figure 3 , the non-linear energy sink comprises a spherical groove track 41 and a spherical mass block 42 placed in the spherical groove track 41, the spherical groove track 41 is fixed on the top of the support rod 45, and the bottom of the support rod 45 is fixed on the buoy 6 through the support 48.

[0033] The surface of the spherical mass block 42 is welded with four annular buckles 44 distributed uniformly in a circumferential array, and the spherical groove track 41 is uniformly distributed with four non-linear springs 43 distributed in a circumferential array, and each non-linear spring 43 is connected with the corresponding annular buckle 44.

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

[0035] As shown in Figure 3 and Figure 4 The inner wall of the cylindrical column 7 is uniformly provided with four fixing members 5 for connecting the nonlinear springs 43 along the circumference. The spherical groove wheel track 41 is uniformly provided with four arc-shaped openings, and each nonlinear spring 43 passes through the corresponding arc-shaped opening.

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

[0037] In the embodiment of the application, 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 fan is subjected to the action of external environmental excitation, the platform generates six degrees of freedom motion, and the spherical mass 42 moves along the spherical groove wheel track 41. Due to the spherical design of the track, the motion trajectory of the spherical mass 42 has the characteristics of multiple degrees of freedom, and can move in different directions. Since the platform will simultaneously move in different directions, the spherical mass 42 can follow the multiple degrees of freedom changes of the platform motion on the track, thereby generating corresponding displacement and reaction force. For example: when the platform rolls or pitches, the spherical mass 42 will move along the front and back or left and right directions of the spherical track; when the platform yaw, the spherical mass 42 will move along the arc trajectory around the center of the platform; when the platform surges and sways, the spherical mass will also displace according to the directions of these translational movements.

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

[0040] As the nonlinear springs 43 are evenly distributed in a circle, the spring system can effectively respond to vibrations in different directions, regardless of the direction of the platform's movement. The motion of the mass is influenced by the interaction of the 4 nonlinear springs 43 arranged in a circular array. The nonlinear characteristics of the springs allow them to exhibit different stiffness at different amplitudes of motion. These nonlinear springs 43 have highly nonlinear mechanical properties. Their stiffness is not fixed but changes dynamically according to the amplitude of the displacement of the spherical mass 42: when the platform produces small amplitude vibrations or displacements, the stiffness of the nonlinear springs 43 is low. This means that the motion of the mass will be subject to a smaller restoring force, making the system's response at small amplitudes more gentle. This characteristic is beneficial for absorbing and dissipating small amplitude vibration energy, preventing the system from being overly sensitive to small disturbances and maintaining the stability of the platform.

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

[0042] At the same time, when the floating platform 3 produces a heave response, the sliding mass 46 will reciprocate up and down along the support rod 45 under the action of the spring 47. The sliding mass moves downward along the support rod under the action of inertia, and at this time the compression spring stores elastic potential energy. The restoring force of the spring pushes the sliding mass to move upward in the opposite direction. It exerts a counteracting force on the platform, offsetting part of the heave energy of the platform, thereby reducing the heave response of the floating platform 3. For different sea conditions, the length of the support rod 45 is changed to adapt to different heave frequencies. Combined with sensors and actuators, the length of the support rod 45 is dynamically adjusted by real-time monitoring of the motion state of the wind turbine platform. Such an active control system can further improve the efficiency of vibration energy absorption, especially in complex marine environments, significantly improving the damping effect.

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

[0044] Hydraulic or electric drive system: through hydraulic cylinder or electric push rod system, the length of the support rod is controlled. The hydraulic cylinder can extend or retract the support rod by applying hydraulic pressure, and the electric push rod adjusts the length by motor drive.

[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 heave.

[0046] Control system: Sensor data is transmitted to the central control unit, which analyzes the frequency and amplitude of motion through algorithms to predict the optimal support rod length.

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

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

[0049] Pre-adjustment function: When the system detects long-period sea conditions, the support rod adjusts its length in advance so that it is in the best state when the sea conditions deteriorate, avoiding lag response.

[0050] The 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 effectively control different vibration amplitudes and directions, significantly increase the vibration reduction frequency band, and achieve wideband vibration absorption. This innovative vibration control method significantly improves the stability and reliability of the floating wind turbine, prolongs the service life of the wind turbine, and has important practical value and wide application prospects.

[0051] The above examples have described the technical solutions and benefits of the invention in detail. It should be understood that the above description is only a specific embodiment of the invention and is not intended to limit the invention. Any modifications, supplements, and equivalent replacements made within the scope of the principles of the invention should be included within the protection scope of the invention.

Claims

1. A multi-degree-of-freedom nonlinear energy sink vibration reduction device applied to an offshore floating wind turbine, characterized in that, The floating platform (3), the tower (2) fixed on the floating platform (3), and the wind turbine generator set (1) installed on the upper part of the tower (2); The floating platform (3) comprises three floating pontoons (6) arranged in an equilateral triangle, and the floating pontoons (6) are fixed to each other; each floating pontoon (6) is provided with a nonlinear energy sink and a cylindrical column (7) sleeved outside the nonlinear energy sink; The nonlinear energy sink comprises a spherical groove track (41) and a spherical mass (42) placed in the spherical groove track (41), the spherical groove track (41) is fixed on the top of a support rod (45), and the bottom of the support rod (45) is fixed on the floating pontoon (6) through a support (48); The surface of the spherical mass (42) is welded with four annular buckles (44) uniformly distributed in a circumferential array, and four nonlinear springs (43) uniformly distributed in a circumferential array are arranged around the spherical groove track (41), and each nonlinear spring (43) is connected with a corresponding annular buckle (44); The support rod (45) is of a segmented telescopic structure and is composed of a plurality of concentrically nested cylinders, and the segments are connected through a mechanical locking mechanism and a driving device; 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; the data of the acceleration sensors and the displacement sensors are transmitted to a central control unit, the frequency and amplitude of the motion are analyzed through an algorithm, and the optimal support rod (45) length is predicted as a target length; an actuator controls the driving device, and after the support rod (45) is driven to the target length, the mechanical locking mechanism fixes the support rod (45), so that the length of the support rod (45) is dynamically adjusted; 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 the floating platform (3), the tower (2), and the wind turbine generator set (1).

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

3. The multi-degree-of-freedom nonlinear energy sink vibration mitigation device for offshore floating wind turbines of claim 1, wherein, The inner wall of the cylindrical column (7) is uniformly provided with four fixing members (5) for connecting the nonlinear springs (43) along the circumference.

4. The multi-degree-of-freedom nonlinear energy sink vibration mitigation device for offshore floating wind turbines of claim 3, wherein, The spherical groove track (41) is uniformly 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 mitigation device for offshore floating wind turbines of claim 1, wherein, When the nonlinear energy sink is installed, part of the ballast mass of the floating platform (3) is replaced with 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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