Lever type dynamic damper in offshore wind turbine tower and control method

Abstract

The invention discloses a lever type dynamic shock absorber in an offshore wind turbine tower drum, which is compact in structure, quick in response and capable of effectively inhibiting the vibration of the offshore wind turbine tower drum under the action of external excitation. The shock absorber comprises an inhaul cable system, a damping shock absorber system, a lever system, an annular guide rail and a horizontal base. The inhaul cable system is connected with a fulcrum of the lever system and is in rotating fit with the lever, and the damping shock absorber is horizontally arranged on the horizontal base. When the tower drum is subjected to external excitation, a differential equation of corresponding vibration response is deduced by establishing a kinetic model of the tower drum and a mass block, and an optimal design scheme of an optimal frequency ratio, fixed point coordinates, system gain and an optimal damping ratio is provided. Displacement amplification and energy dissipation can be achieved through the lever principle, so that the vibration amplitude of the tower drum is remarkably reduced, the stability of an offshore wind turbine system is improved, and the service life of the offshore wind turbine system is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of vibration control, and particularly to a lever-type dynamic vibration absorber inside an off-shore wind turbine tower and a control method thereof. Background Art

[0002] A dynamic vibration absorber is a common shock-absorbing device in the field of vibration control. Its principle is to attach a mass-spring system to a vibrating object. The reaction force generated by this additional system at resonance can reduce the vibration of the vibrating object. In recent years, due to the long-term action of wind loads, sea waves and other environmental excitations, the vibration problem of the tower barrel of off-shore wind turbines has become increasingly prominent.

[0003] 1. Comparative document CN117927427B discloses an off-shore wind power tower barrel provided with a lever-type dynamic vibration absorber and an assembly method thereof, including: a tower barrel body, a lever module, a damping module and an auxiliary vibration module; the lever module includes a plurality of levers arranged around the wind power tower barrel, and the upper ends of the levers are connected to the wind power tower barrel; the damping module includes mass-inertia dampers with the same number as the levers, and both ends of the mass-inertia dampers are respectively connected to the lower ends of the levers and the platform; the auxiliary vibration module includes a strut assembly and a support mechanism, the strut assembly includes struts with the same number as the levers and having protrusions, and the protrusions are hinged to the lever bodies; the support mechanism is arranged on the wind power platform and fixedly connected to the struts. The method is used for assembling the above-mentioned off-shore wind power tower barrel. The novel wind power tower barrel structure proposed by the present invention can adapt to more complex wind, wave and current coupling effects and seismic effects, and can improve the current situation of poor anti-vibration performance of existing off-shore wind power structures, but parameter adjustment depends on manual work and cannot adapt to real-time working conditions; 2. Comparative document CN117889046B discloses an off-shore wind power tower barrel provided with an inertia capacitance dynamic vibration absorber and a construction method thereof, including: a tower barrel body, and a first protection unit and / or a second protection unit installed inside the tower barrel body; the wind power tower barrel is installed on an off-shore floating platform; the first and second protection units respectively include a plurality of functional components rotatably installed on the upper and lower parts of the tower barrel body; the functional components are obliquely arranged and include an upper connecting rod member, an inertia capacitance dynamic vibration absorber and a lower connecting rod member connected in sequence. The construction method includes: determining the layout mode of the functional components inside the tower barrel body according to requirements; assembling the upper connecting rod member, the inertia capacitance dynamic vibration absorber and the lower connecting rod member to form a functional component; and rotatably installing the functional component inside the tower barrel body according to the layout mode. The wind power tower barrel of the present invention can adapt to more complex wind, wave and current coupling effects and seismic effects, can realize multi-directional energy dissipation and vibration reduction of the wind power tower barrel, and has a good vibration absorption effect, but has a complex structure, a high manufacturing cost, and requires external energy drive.

[0004] In summary, the main problems of the existing technologies are that traditional shock absorber designs mostly adopt simple damping and tuned mass block structures, but they have limitations in terms of dynamic response speed, adjustment range, and energy dissipation capacity, and it is difficult to meet the strict requirements for vibration control of offshore wind turbines under extreme working conditions.

[0005] Therefore, a lever-type dynamic shock absorber and control method inside the tower barrel of an offshore wind turbine are proposed to solve the above problems. Summary of the Invention

[0006] The present invention proposes a lever-type dynamic shock absorber inside the tower barrel of an offshore wind turbine for the above problems, which includes a cable system, a lever system, a damping shock absorber system, a horizontal base, and an annular guide rail; The cable system includes a cable rod, the cable rod vertically penetrates the center of the horizontal base to connect the ground and the top of the tower barrel, and a lever fulcrum is provided in the middle of the cable rod to connect with the center point of the lever system for transmitting the vibration of the tower barrel; The lever system includes a first annular lever group and a second annular lever group. The first annular lever group is sleeved inside the second annular lever group. Each of the two annular lever groups includes two parallel circular ring levers. The long arm ends of them are hinged to the damping shock absorber system through the first sliding cylinder, and the short arm ends are matched with the linear track arranged inside the annular guide rail through the second sliding cylinder to form a displacement amplification transmission mechanism. The lever fulcrum block of the circular ring lever has a threaded part at the front end of the lever fulcrum in the cable system fixed by a hexagon nut, and the non-threaded part at the rear end is matched with the hole of the lever fulcrum block to ensure the rotation and telescopic displacement of the circular ring lever; The damping shock absorber system is arranged on the upper surface of the horizontal base and includes four groups of viscous dampers, horizontal springs, and mass blocks. The viscous dampers are connected in parallel with the horizontal springs, one end is connected to the mass block, and the other end is connected to the slider support. A first sliding cylinder is provided in the middle of the bottom of the slider support, and the mass block contacts the horizontal base through balls; The annular guide rail includes an annular outer ring and four linear guide rails. One ends of the four linear guide rails are connected to the same inner ring, and the other ends are connected to the inner wall of the annular outer ring. The included angles of the four linear guide rails are evenly distributed at an angle of 45°. The annular outer ring is rigidly connected to the tower barrel, and the side wall of the linear guide rail is provided with a second sliding cylinder to restrict the movement track of the lever system.

[0007] Preferably, the ratio of the long arm to the short arm of the circular ring lever of the lever system is a key parameter for controlling the displacement amplification multiple, and the value range of the ratio of the long arm to the short arm is 2:1 to 4:1. The circular ring lever is made of high-strength aluminum alloy material.

[0008] Preferably, the annular guide rail is made of high-strength stainless steel with a galvanized surface. The linear track in the annular guide rail is sleeved with the short arm end of the circular lever through a second slide cylinder to form a transmission mechanism. The side wall of the second slide cylinder is hingedly arranged on the side wall of the linear guide rail.

[0009] Preferably, the total length of the cable system is determined according to the tower height, and a tension adjustment margin is reserved. The lever fulcrum of the cable is made of fine steel, the center hole diameter is 20 mm, and the surface is chrome-plated for corrosion protection.

[0010] Preferably, the surfaces of all metal parts are sprayed with polyurethane anti-corrosion paint, and the damper piston rod is chrome-plated with a coating thickness of 20 μm.

[0011] Preferably, each set of damping shock absorbers is provided with a backup spring and damper.

[0012] In addition, the present invention also discloses a control method for a lever-type dynamic vibration absorber inside an offshore wind turbine tower, which is characterized by comprising the following steps: Step 1: Transmit and amplify the tower vibration displacement through the lever system: When the tower is displaced by external excitation When the vibration is transmitted to the lever system through the second slide cylinder, the lever system rotates around the fulcrum on the cable through the unequal length arms. and Amplify the vibration displacement of the tower times, and transmits the amplified displacement to the damping shock absorber system; Step 2: Multi-degree-of-freedom synergy of the damping and vibration absorber system: the damping and vibration absorber system comprises four sets of orthogonally arranged subsystems, each of which triggers the synergy of the viscous damper and the horizontal spring through the displacement of the slide support to suppress the vibration of the tower; Step 3: Optimize damping parameters based on the amplification effect: and leverage ratio , the calculation expression of the optimal damping ratio is: ; Based on this calculation, the damping coefficient c of the damping shock absorber is configured to achieve efficient dissipation of vibration energy.

[0013] Furthermore, in step one, the lever system is composed of two groups of parallel circular levers, the short arm end of each group of circular levers is slidably matched with the linear track of the annular guide rail through the second slide cylinder, and the long arm end is transmission connected to the slide cylinder of the damping shock absorber system to form a multi-degree-of-freedom displacement amplification mechanism.

[0014] Further, in the second step, the sliding cylinder supports and the bottoms of the mass blocks of each subsystem of the damping shock absorber system are in contact with the horizontal base through balls to ensure low-friction movement in the horizontal direction.

[0015] Further, in the third step, the calculation of the optimal damping ratio further includes: Determining the optimal frequency ratio through the fixed-point theory, and its expression is: ; Based on the maximum condition of the amplitude magnification factor M, combined with the lever ratio γ and the mass ratio μ, the optimal damping ratio can be derived .

[0016] The present invention has the following beneficial effects: 1. The lever-type dynamic shock absorber of the present invention has a compact structure and is integrally installed inside the tower barrel of the offshore wind turbine. Displacement amplification is achieved through the lever principle, so as to efficiently absorb and dissipate vibration energy; 2. Relying on accurate dynamic modeling and the optimized design of key parameters such as the lever ratio, the optimal frequency ratio, and the damping ratio, the system can significantly reduce the vibration amplitude of the tower barrel, improve the overall stability and safety, extend the service life of the equipment, and at the same time simplify the installation and maintenance process. Description of the Drawings

[0017] Figure 1 is the structural schematic diagram of the present invention; Figure 2 is the structural schematic diagram of the cable system of the present invention; Figure 3 is the structural schematic diagram of the damping shock absorber system of the present invention; Figure 4 is the structural schematic diagram of the lever system of the present invention; Figure 5 is the structural schematic diagram of the annular guide rail of the present invention; Figure 6 is the structural schematic diagram of the circular ring lever of the present invention; Figure 7 is the schematic diagram of the dynamic model of the damping shock absorber system of the present invention; Figure 8 is the amplitude-frequency response curve diagram of the present invention and the traditional Voigt dynamic vibration absorber when they have the same additional mass and take the optimal parameters.

[0018] Wherein: 1 cable system; 2 damping shock absorber system; 3 lever system; 4 horizontal base; 5 annular guide rail; 101 cable; 102 lever fulcrum; 201 first sliding cylinder; 202 sliding cylinder support; 203 viscous damper; 204 horizontal spring; 205 mass block; 206 ball; 207 cylindrical pin; 301 ring lever; 302 ring lever; 303 ring lever; 304 ring lever; 305 lever fulcrum block; 501 guide rail outer ring; 502 linear guide rail; 503 linear guide rail; 504 linear guide rail; 505 linear guide rail; 506 second sliding cylinder. Specific implementation manner

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments: Referring to Figures 1 to 6 As shown in the structure, this embodiment provides a lever-type dynamic damper inside the tower barrel of an offshore wind turbine, which mainly includes a cable system 1, a damping shock absorber system 2, a lever system 3, a horizontal base 4, and an annular guide rail 5.

[0020] The cable system includes a cable rod 101 and a lever fulcrum 102 arranged on the cable. One end of the cable is fixed to the ground, and the other end is connected to the top of the tower barrel. The lever fulcrum 102 is arranged at a position above the cable 101. Through the cable system 1, the vibration at the top of the tower barrel is transmitted to the lever fulcrum 102 and drives the lever system 3 to generate a rotational motion; The damping shock absorber system 2 is composed of a first sliding cylinder 201, a sliding cylinder support 202, a viscous damper 203, a horizontal spring 204, a mass block 205, and a ball 206. The bottom of the sliding cylinder support 202 is hinged with the first sliding cylinder 201, and the first sliding cylinder 201 can rotate around the hinge point, enabling smooth rotation during system vibration; one end of the viscous damper 203 is connected to the sliding cylinder support 202, and the other end is connected to the mass block 205. At the same time, one end of the horizontal spring 204 is connected to the sliding cylinder support 202, and the other end is connected to the mass block 205 through a cylindrical pin 207. The bottoms of the mass block 205 and the sliding cylinder support 202 are both placed on the horizontal base 4 through balls 206; when the tower barrel is subjected to external excitation, the system 2 acts jointly through the viscous damper 203 and the horizontal spring 204; The lever system 3 includes two parallel ring levers 301 and 302, and two parallel ring levers 303 and 304. The inner ring diameter of the ring levers 301 and 302 is slightly smaller than that of the ring levers 303 and 304. One end of each ring lever is fitted with the first sliding cylinder 201 in the damping shock absorber system 2, and the other end is fitted with the annular guide rail 5 through the second sliding cylinder 506 to form a transmission mechanism. The lever fulcrum block 305 of the ring lever is fixed to the front threaded part of the lever fulcrum 102 in the cable system 1 by a hexagon nut, and the rear non-threaded part is fitted with the hole of the lever fulcrum block 305, enabling the ring lever to rotate and displace telescopically around the lever fulcrum 102; The outer ring 501 of the annular guide rail 5 is rigidly connected to the tower barrel. The guide rail is internally provided with linear tracks 1, 2, 3, and 4. The four linear tracks and the outer ring 501 are arranged in the same plane. The four linear tracks are respectively fitted with the ring levers 301, 302, 303, and 304 through the second sliding cylinder 506. One end of the four linear guide rails is connected to the same inner ring, and the other end is connected to the inner wall of the annular outer ring 501. The included angles of the four linear guide rails are evenly distributed at an angle of 45°. The annular outer ring 501 is rigidly connected to the tower barrel, and the side wall of the linear guide rail is provided with the second sliding cylinder 506 to restrict the movement track of the lever system 3.

[0021] Preferably, the ratio of the long arm to the short arm of the ring lever of the lever system 3 is a key parameter for controlling the displacement magnification factor, where the ratio of the long arm to the short arm ranges from 2:1 to 4:1, and the ring lever is made of high-strength aluminum alloy material.

[0022] Preferably, the annular guide rail is made of high-strength stainless steel material and is surface galvanized. The linear track in the annular guide rail is sleeved and fitted with the short arm end of the ring lever through the second sliding cylinder 506 to form a transmission mechanism, and the side wall of the second sliding cylinder is hinged to the side wall of the linear guide rail.

[0023] Preferably, the total length of the cable system is determined according to the height of the tower barrel, and a tension adjustment margin is reserved. The lever fulcrum of the cable is made of precision steel, with a central hole diameter of 20 mm and surface chromium plating for corrosion prevention.

[0024] Preferably, the surfaces of all metal components are sprayed with polyurethane anti-corrosion paint, and the piston rod of the damper adopts a chromium plating process with a plating thickness of 20 μm.

[0025] Preferably, each group of damping shock absorbers is equipped with a spare spring and a damper.

[0026] In addition, the present invention also discloses a control method for a lever-type dynamic shock absorber inside a tower barrel of an offshore wind turbine, which is characterized by including the following steps: Step 1: Transmit and amplify the tower vibration displacement through the lever system: When the tower is displaced by external excitation When the vibration is transmitted to the lever system 3 through the second slide cylinder 506, the lever system 3 rotates around the fulcrum 102 on the cable 101 through the unequal length arms. and Amplify the vibration displacement of the tower times, and transmits the amplified displacement to the damping shock absorber system 2; Step 2: Multi-degree-of-freedom synergy of the damping vibration absorber system: The damping vibration absorber system 2 comprises four sets of orthogonally arranged subsystems, each of which triggers the synergy of the viscous damper 203 and the horizontal spring 204 through the displacement of the slide support 202 to suppress the vibration of the tower; Step 3: Optimize damping parameters based on the amplification effect: and leverage ratio , the calculation expression of the optimal damping ratio is: ; Based on this calculation, the damping coefficient c of the damping shock absorber is configured to achieve efficient dissipation of vibration energy.

[0027] Furthermore, in step one, the lever system 3 is composed of two groups of parallel circular levers, the short arm end of each group of circular levers is slidably matched with the linear track of the annular guide rail 5 through the second slide cylinder 506, and the long arm end is transmission connected to the slide cylinder 201 of the damping shock absorber system 2, forming a multi-degree-of-freedom displacement amplification mechanism.

[0028] Furthermore, in the step 2, the bottom of the slide support 202 and the mass block 205 of each subsystem of the damping shock absorber system 2 are in contact with the horizontal base 4 through the ball 206 to ensure low-friction movement in the horizontal direction.

[0029] Furthermore, in step 3, the calculation of the optimal damping ratio further includes: The optimal frequency ratio is determined by fixed point theory, and its expression is: ; Based on the maximum condition of the amplitude amplification factor M, combined with the lever ratio γ and the mass ratio μ, the optimal damping ratio can be derived: .

[0030] Embodiment 1 Assume the mass of the tower is , the stiffness is , the displacement is , the cable swing angle is a. Since the swing angle is a small amount relative to the tower height, the swing angle can be set to 0 for calculation. The mass of the mass block is , the damping of the viscous damper is \(c\), and the stiffness of the horizontal spring is , then Figure 7 the differential equation of the vibration system model in ; Introduce the lever ratio , assuming the excitation is a harmonic force , and the response is , substituting into the differential equation and arranging, the amplitude magnification factor \(M\) of the tower barrel can be obtained as:

[0031] where is the natural frequency ratio; is the normalized frequency ratio; is the mass ratio; is the natural frequency of the main system; is the natural frequency of the vibration absorber; is the damping ratio; is the ratio of the long arm to the short arm of the lever.

[0032] According to the fixed-point theory, there are two fixed points \(S\) and \(T\) on the amplitude-frequency curve at a specific frequency ratio, and their abscissas are: ; ; The ordinates of points \(S\) and \(T\) are respectively: ; ; Adjust the ordinates of points \(S\) and \(T\) to the same height, that is the optimal frequency ratio can be obtained: ; Substitute the optimal frequency ratio into it to obtain the abscissas at the two fixed points \(S\) and \(T\) ; ; When the frequency ratio is the optimal value, the ordinates at the two fixed points \(S\) and \(T\) are ; In order to make the vibration effect reach the best, according to the extreme value condition, adjust the two fixed points to the highest point, then the maximum value point \(\lambda\) of the magnification factor \(M\) satisfies ; Wherein: ; Let , then there is , substituting it in can obtain: ; Substituting the optimal frequency ratio into it can obtain: ; Substituting the abscissas of points S and T into the formula respectively to obtain ; Obtaining the optimal damping ratio .

[0033] Embodiment 2: Comparing the present invention with the traditional Voigt type dynamic vibration absorber model, as Figure 8 shown, when the present invention and the traditional Voigt dynamic vibration absorber have the same additional mass and take the optimal parameters, the vibration damping performance of the dynamic vibration absorber of the present invention is more excellent and can effectively suppress the amplitude of the tower barrel.

[0034] Table 1 Main system parameters

[0035] Table 2 Parameters of the Voigt type dynamic vibration absorber

[0036] Table 3 Parameters of the dynamic vibration absorber of the present invention

[0037] The above embodiments are only the preferred technical solutions of the present invention and should not be regarded as limitations on the present invention. The protection scope of the present invention should be the technical solutions recorded in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, the equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A lever-type dynamic damper inside an offshore wind turbine tower, characterized in that It includes a cable system, a lever system, a damping shock absorber system, a horizontal base and a circular guide rail; The cable system includes a cable rod, which vertically passes through the center of the horizontal base and connects the ground and the top of the tower. A lever fulcrum is provided in the middle of the cable rod and is connected to the center point of the lever system for transmitting tower vibration. The lever system comprises a first annular lever group and a second annular lever group, wherein the first annular lever group is sleeved in the ring of the second annular lever group, and the two annular lever groups respectively comprise two parallel annular levers, whose long arm ends are hinged to the damping shock absorber system through the first slide cylinder, and whose short arm ends are matched with the linear track set in the annular guide rail through the second slide cylinder, so as to form a displacement amplification transmission mechanism, and the lever fulcrum block of the annular lever is fixed with the front end threaded part of the lever fulcrum in the cable system through the hexagonal nut, and the rear end non-threaded part is matched with the hole of the lever fulcrum block, so as to ensure the rotation and telescopic displacement of the annular lever; The damping shock absorber system is arranged on the upper surface of the horizontal base, and includes four groups of viscous dampers, a horizontal spring and a mass block. The viscous damper is connected in parallel with the horizontal spring, one end of which is connected to the mass block, and the other end is connected to the slider support. A first sliding cylinder is arranged in the middle of the bottom of the slider support, and the mass block contacts the horizontal base through a ball bearing. The annular guide rail comprises an annular outer ring and four linear guide rails, one end of the four linear guide rails is connected to the same inner ring, and the other end is connected to the inner wall of the annular outer ring, the four linear guide rails are evenly distributed at an angle of 45°, the annular outer ring is rigidly connected to the tower, and the side wall of the linear guide rail is provided with the motion trajectory of the second slide cylinder constraint lever system.

2. The lever-type dynamic damper inside the tower barrel of an offshore wind turbine according to claim 1, characterized in that, The ratio of the long arm to the short arm of the circular lever of the lever system is a key parameter for controlling the displacement magnification, wherein the ratio of the long arm to the short arm ranges from 2:1 to 4:1, and the circular lever is made of high-strength aluminum alloy material.

3. The internal lever-type dynamic damper for an offshore wind turbine tower according to claim 1, wherein, The annular guide rail is made of high-strength stainless steel material and is galvanized on the surface. The linear track in the annular guide rail is sleeved and matched with the short arm end of the circular lever through the second slide cylinder to form a transmission mechanism. The side wall of the second slide cylinder is hingedly arranged on the side wall of the linear guide rail.

4. The internal lever-type dynamic damper for an off-shore wind turbine tower according to claim 1, wherein, The total length of the cable system is determined according to the tower height, and a tension adjustment margin is reserved. The lever fulcrum of the cable is made of fine steel, the center hole diameter is 20mm, and the surface is chrome-plated for corrosion protection.

5. A lever-type dynamic damper inside an off-shore wind turbine tower according to claim 1, characterized in that, All metal parts are sprayed with polyurethane anti-corrosion paint, and the damper piston rod is chrome-plated with a coating thickness of 20μm.

6. The lever type dynamic vibration absorber inside the tower barrel of an offshore wind turbine according to claim 1, characterized in that, Each set of damping shock absorbers is equipped with spare springs and dampers.

7. A control method for a lever-type dynamic vibration absorber inside an offshore wind turbine tower according to any one of claims 1-6, characterized in that, The following steps are involved: Step 1. Transmit and amplify the vibration displacement of the tower barrel through a lever system: When the tower barrel generates displacement under external excitation the vibration is transmitted to the lever system through the second sliding cylinder. The lever system rotates around the fulcrum on the cable, and through unequal-length arms and amplify the vibration displacement of the tower barrel times and transmit the amplified displacement to the damping and vibration reduction system; Step 2: Multi-degree-of-freedom synergy of the damping and vibration absorber system: the damping and vibration absorber system comprises four sets of orthogonally arranged subsystems, each of which triggers the synergy of the viscous damper and the horizontal spring through the displacement of the slide support to suppress the vibration of the tower; Step 3. Optimize the damping parameter by magnification effect: According to the mass ratio and the lever ratio , the calculation expression of the optimal damping ratio is: ； Based on this calculation, the damping coefficient c of the damping shock absorber is configured to achieve efficient dissipation of vibration energy.

8. The control method of a lever-type dynamic vibration absorber inside an offshore wind turbine tower according to claim 7, characterized in that, In step one, the lever system is composed of two groups of parallel circular levers, the short arm end of each group of circular levers is slidably matched with the linear track of the annular guide rail through the second slide cylinder, and the long arm end is transmission connected to the slide cylinder of the damping shock absorber system to form a multi-degree-of-freedom displacement amplification mechanism.

9. The control method of a lever-type dynamic damper inside an off-shore wind turbine tower according to the claim, characterized in that, In the second step, the sliding cylinder supports and the bottoms of the mass blocks of each subsystem of the damping shock absorber system are in contact with the horizontal base through balls to ensure low-friction movement in the horizontal direction.

10. A control method for a lever-type dynamic vibration absorber inside an offshore wind turbine tower barrel according to claim 7, characterized in that, In the third step, the calculation of the optimal damping ratio further includes: Determining the optimal frequency ratio through the fixed-point theory, and its expression is: ； Based on the maximum condition of the amplitude amplification factor M, combined with the leverage ratio γ and the mass ratio μ, the optimal damping ratio can be derived. .

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