A fan blade vibration damping system

Abstract

The present invention discloses a vibration damping system for a wind turbine blade, which comprises a plurality of damping devices uniformly arranged inside the blade along the direction perpendicular to the chord direction of the blade; each damping device includes two electromagnetic damping units, two transmission units and a tuned mass damper unit, wherein one electromagnetic damping unit is arranged at the leading edge position of the blade tip, and the other is arranged at the PS surface or SS surface position of the blade tip. One ends of the two transmission units are respectively connected to the two electromagnetic damping units. The tuned mass damper unit is arranged at the blade middle position and is located between the two webs of the blade. It includes a double-layer damping structure which is respectively connected to the other ends of the two transmission units. The present invention can effectively solve the problem of large amplitudes in the flap and pitch directions of the wind turbine blade.

Description

Technical Field

[0001] The present invention relates to the technical field of blades of renewable new energy wind turbines, and in particular to a vibration damping system for wind turbine blades. Background Art

[0002] With the increasing enlargement of wind turbines, more and more problems are faced, especially for blades with a relatively large aspect ratio. When under the action of the oncoming wind, due to the large flexibility of the blades, especially large vibrations will occur in the flapping and pitching directions. In an actual wind farm, if the blades are in a state of large vibration for a long time, it is very likely that buckling deformation will occur and fatigue damage will be suffered, which is the so-called aeroelastic instability. Aeroelastic instability is often the classical flutter and stall flutter that we mentioned. Classical flutter is often a divergent and self-excited unstable vibration form generated under the combined action of torsion and flapping. The vibration fluid in this case belongs to the attached state and will not produce flow separation. Its occurrence is often due to the phase difference between the fluid force and the deformation displacement of the blade, thus further extracting more energy from the fluid and causing the blade vibration to diverge. When stall flutter occurs, serious airflow separation will often occur and be accompanied by strong vortex fluctuations. Usually, the occurrence of stall flutter is often due to the fact that the lift system of the wind turbine blade is near the stall angle of attack, thus triggering a serious aeroelastic instability phenomenon. Compared with stall flutter, the vibration response of classical flutter is stronger. Its occurrence is usually closely related to the bending-torsion coupling effect of the blade and is due to the coupling action of pitching, flapping, and torsion triggered by the first-order pitching frequency of the blade. Therefore, in any sense, aeroelastic instability will cause serious problems for wind turbine blades. Therefore, how to solve the vibration divergence has become a hot research topic.

[0003] In real life, the vibration damping methods we usually adopt are divided into two control strategies: active and passive. Active control usually includes what is called aerodynamic tailoring, adjusting the aerodynamic shape of the blade, etc. to reduce blade vibration. Aerodynamic tailoring is to use composite materials to change the inherent vibration characteristics of the blade and use the deformation of the blade to change the aerodynamic characteristics of the blade, so as to achieve blade vibration suppression. The change of the aerodynamic shape is usually achieved by adjusting the appropriate twist angle, relative thickness, and chord length distribution to achieve stall delay of the blade at a large angle of attack. Passive control is to make modifications to the wind aerodynamic shape, including adding vortex generators, trailing edge flaps, etc. to achieve the effect of delaying flow separation, which can reduce vibration to a certain extent. Whether it is active control or passive control, it requires a long R & D and experimental cycle. For example, the change of the aerodynamic shape needs to be verified through simulation, wind tunnel experiments, etc. Compared with these methods, a more efficient and rapid load reduction can also be achieved through a dynamic vibration damping system. Summary of the Invention

[0004] The object of the present invention is to overcome the deficiencies of the prior art and provide a vibration damping system for a fan blade, which can effectively solve the problem of large amplitudes in the flapping and pitching directions of the fan blade. By adding multiple damping devices inside the blade, the amplitudes in the tip flapping and pitching directions are effectively reduced.

[0005] To achieve the above object, the technical solution provided by the present invention is: a vibration damping system for a fan blade, comprising a plurality of damping devices, which are uniformly arranged inside the blade along a direction perpendicular to the chord of the blade; each damping device includes two electromagnetic damping units, two transmission units and a tuned mass damper unit. The two electromagnetic damping units are respectively a first electromagnetic damping unit and a second electromagnetic damping unit. The first electromagnetic damping unit is arranged at the leading edge position of the blade tip, and the second electromagnetic damping unit is arranged at the PS surface or SS surface position of the blade tip. The metal sliders in the two electromagnetic damping units slide under the action of inertial force, and drive the metal coils therein to cut the magnetic induction lines in the magnetic field, so that a part of the vibration energy from the tip flapping and pitching is dissipated in the form of heat energy. The two transmission units are respectively a first transmission unit and a second transmission unit. One ends of the first transmission unit and the second transmission unit are respectively connected to the first electromagnetic damping unit and the second electromagnetic damping unit. The tuned mass damper unit is arranged at the mid-span position of the blade and is located between the two webs of the blade. It includes a double-layer damping structure, and the double-layer damping structure is respectively connected to the other ends of the first transmission unit and the second transmission unit. Another part of the vibration energy from the tip flapping and the vibration energy from the tip pitching are respectively transmitted to the double-layer damping structure through the two transmission units and dissipated, so as to achieve the purpose of reducing the blade vibration.

[0006] Further, the electromagnetic damping unit includes a connection base, an N magnetic pole, an S magnetic pole, a metal fixing block, a metal slider, a metal coil and a first spring. The connection base is fixed at the leading edge, PS surface or SS surface position of the blade tip, and a groove for installing the N magnetic pole, S magnetic pole, metal fixing block, metal slider, metal coil and first spring is formed thereon. The N magnetic pole and the S magnetic pole are respectively fixed on both inner sides of the groove. The metal fixing block is fixed at the bottom of the groove and is located between the N magnetic pole and the S magnetic pole. The metal slider is slidably installed at the notch of the groove and is located between the N magnetic pole and the S magnetic pole, and is connected to the first transmission unit or the second transmission unit. The metal coil is arranged between the N magnetic pole and the S magnetic pole and is located between the metal slider and the metal fixing block, and its two ends are respectively connected to the metal fixing block and the metal slider by the first spring.

[0007] Further, the first spring is a corrugated spring, an annular spring or a butterfly spring.

[0008] Further, the tuned mass damper unit includes a first metal fixing plate, a second fixing plate, a third fixing plate, a first mass block, a second mass block, a partition, a first metal fixing seat, a second metal fixing seat, a third metal fixing seat, a second spring, a first metal slider, a second metal slider, a first metal plate, and a second metal plate. The first metal fixing plate is fixed between the two webs of the blade. One end of the second fixing plate and the third fixing plate are respectively vertically connected to the upper and lower parts of the first metal fixing plate, and the other ends are respectively oriented toward the blade tip direction and are respectively fixed between the two webs through the first metal fixing seat and the third metal fixing seat. U-shaped slideways for sliding the first mass block and the second mass block are respectively formed on two opposite side surfaces of the second fixing plate and the third fixing plate. The first mass block and the second mass block are separated by a partition. The two ends of the partition are respectively fixed between the two webs through the first metal fixing plate and the second metal fixing seat, and the second metal fixing seat is located between the first metal fixing seat and the third metal fixing seat. The first mass block One end of the first and second mass blocks are respectively connected to the first metal fixing plate through a plurality of second springs, and the other ends are respectively connected to the first metal slider and the second metal slider through a plurality of second springs; two first metal plates arranged parallel to each other are provided on the bottom surface of the first metal fixing seat and the top surface of the second metal fixing seat, and slideways for the first metal slider to slide are formed on the opposite sides of the two first metal plates; two second metal plates arranged parallel to each other are provided on the bottom surface of the second metal fixing seat and the top surface of the third metal fixing seat, and slideways for the second metal slider to slide are formed on the opposite sides of the two second metal plates; the first metal slider is connected to the first electromagnetic damping unit through the first transmission unit, and the first layer of damping structure for dissipating the vibration energy from the blade tip swinging is formed by the first mass block, the first metal slider and the corresponding second spring; the second metal slider is connected to the second electromagnetic damping unit through the second transmission unit, and the second layer of damping structure for dissipating the vibration energy from the blade tip swinging is formed by the second mass block, the second metal slider and the corresponding second spring.

[0009] Furthermore, the second spring is a wave spring, an annular spring or a butterfly spring.

[0010] Furthermore, the first mass block and the second mass block are both metal structures or magnetic structures.

[0011] Furthermore, the second fixing plate and the third fixing plate are both metal structures or magnetic structures.

[0012] Further, the drive unit includes a pulley bracket, a pulley and a wire rope. The pulley bracket is fixed inside the blade in a direction perpendicular to the chord of the blade and is located between the blade root and the blade tip. A pulley is slidably mounted on the pulley bracket. One end of the wire rope is connected to the first metal slider or the second metal slider of the tuned mass damper unit, and the other end passes around the pulley and is connected to the first electromagnetic damper unit or the second electromagnetic damper unit.

[0013] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0014] 1. By using the damping system of the present invention, the energy at the blade tip is converted into mechanical energy, spring potential energy, electromagnetic energy, and thermal energy, which can maximize the consumption of the blade tip energy while reducing the risk of aeroelastic instability of the blade.

[0015] 2. The damping system of the present invention overcomes the limitation in the blade tip space and transfers the energy at the blade tip to the tuned mass damper unit at the blade root through the drive unit for dissipation, maximizing the role of the tuned mass damper unit.

[0016] 3. The damping system of the present invention is fixed between the two webs. When connecting the wire rope, only a hole needs to be drilled through the metal slider, and there is no need to change the structure of the web, thus avoiding the problem of strong stress concentration on the web. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of the electromagnetic damper unit of the damping system of the present invention.

[0018] Figure 2 is a schematic structural diagram of the tuned mass damper unit of the damping system of the present invention.

[0019] Figure 3 is Figure 2 the sectional view taken along A-A in

[0020] Figure 4 is Figure 2 the sectional view taken along B-B in

[0021] Figure 5 is a schematic installation diagram of the tuned mass damper unit inside the blade of the present invention.

[0022] Figure 6 is a schematic installation diagram of the electromagnetic damper unit and the drive unit inside the blade of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention will be further described below in conjunction with specific embodiments, but the usage mode of the present invention is not limited thereto.

[0024] Such as Figures 1 to 6As shown in the figure, the fan blade vibration damping system described in this embodiment includes a plurality of damping devices. The plurality of damping devices are uniformly arranged inside the blade in a direction perpendicular to the chord direction of the blade, and the distance between two adjacent damping devices is reasonably adjusted and distributed according to the structure of the actual blade (including chord length, twist angle, maximum thickness, etc.); each damping device includes two electromagnetic damping units 1, two transmission units 2, and a tuned mass damper unit 3. The two electromagnetic damping units 1 are respectively a first electromagnetic damping unit and a second electromagnetic damping unit. The first electromagnetic damping unit is arranged at the leading edge position of the blade tip, and the second electromagnetic damping unit is arranged at the PS surface or SS surface position of the blade tip. The metal sliders in the two electromagnetic damping units 1 slide under the action of inertia force, and drive the metal coils inside them to cut the magnetic induction lines in the magnetic field, so that a part of the vibration energy from the flapping and waving of the blade tip is dissipated in the form of heat. The two transmission units 2 are respectively a first transmission unit and a second transmission unit. One ends of the first transmission unit and the second transmission unit are respectively connected to the first electromagnetic damping unit and the second electromagnetic damping unit. The tuned mass damper unit 3 is arranged at the mid-span position of the blade and is located between the two webs of the blade. It includes a double-layer damping structure, and the double-layer damping structure is respectively connected to the other ends of the first transmission unit and the second transmission unit. Another part of the vibration energy from the flapping of the blade tip and the vibration energy from the waving of the blade tip are respectively transmitted to the double-layer damping structure through the two transmission units 2 and dissipated, so as to achieve the purpose of reducing blade vibration.

[0025] As Figure 2 As shown in the figure, the electromagnetic damping unit 1 includes a connecting base 101, an N magnetic pole 102, an S magnetic pole 103, a metal fixing block 104, a metal slider 105, a metal coil 106, and a first spring 107. The connecting base 101 is fixed at the leading edge, PS surface or SS surface position of the blade tip, and a groove for installing the N magnetic pole 102, S magnetic pole 103, metal fixing block 104, metal slider 105, metal coil 106, and first spring 107 is formed thereon. The N magnetic pole 102 and the S magnetic pole 103 are respectively fixed on both sides inside the groove. The metal fixing block 104 is fixed at the bottom of the groove and is located between the N magnetic pole 102 and the S magnetic pole 103. The metal slider 105 is slidably installed at the notch of the groove and is located between the N magnetic pole 102 and the S magnetic pole 103, and is connected to the first transmission unit or the second transmission unit. The metal coil 106 is arranged between the N magnetic pole 102 and the S magnetic pole 103 and is located between the metal slider 105 and the metal fixing block 104, and its two ends are respectively connected to the metal fixing block 104 and the metal slider 105 by the first spring 107.

[0026] When the tip of the blade deforms due to a relatively high oncoming wind speed, the electromagnetic damping unit 1 will move along with the blade. At this time, the metal slider 105 will slide relative to the connecting base under the action of inertia force, and then drive the metal coil 106 to move in the magnetic field formed by the N pole 102 and the S pole 103 to cut the magnetic induction lines, and finally dissipate the vibration energy in the form of a certain amount of heat energy. At the same time, the first spring 107 and the metal slider 105 also form a tuned mass damper (TMD), which also plays a certain role in attenuating the amplitude.

[0027] Preferably, the first spring can be any spring with good damping performance, such as a corrugated spring, an annular spring or a butterfly spring.

[0028] The transmission unit 2 includes a pulley bracket 201, a pulley 202 and a steel wire rope 203. The pulley bracket 201 is fixed inside the blade in a direction perpendicular to the chord direction of the blade and is located between the blade root and the blade tip. A pulley 202 is slidably installed on the pulley bracket 201. Multiple transmission units 2 can also share a pulley bracket. Among them, the rotation axes of the pulleys 202 of two transmission units are perpendicular to each other, that is, one rotation axis is parallel to the axial direction of the pulley bracket 201, and the other rotation axis is perpendicular to the axial direction of the pulley bracket 201. One end of the steel wire rope 203 is connected to the first metal slider 311 or the second metal slider 312 of the tuned mass damper unit 3, and the other end bypasses the pulley 202 and is connected to the first electromagnetic damping unit or the second electromagnetic damping unit. The steel wire ropes connected to the first electromagnetic damping unit and the second electromagnetic damping unit are respectively wound around the pulleys in two different rotation directions. The steel wire rope 203 can be adjusted to steel wire ropes with different strengths, different tensions and different traction forces according to the environmental conditions of the wind field to meet different requirements.

[0029] The tuned mass damper unit 3 includes a first metal fixing plate 301, a second fixing plate 302, a third fixing plate 303, a first mass block 304, a second mass block 305, a partition 306, a first metal fixing seat 307, a second metal fixing seat 308, a third metal fixing seat 309, a second spring 310, a first metal slider 311, a second metal slider 312, a first metal plate 313 and a second metal plate 314. The first metal fixing plate 301 is fixed between the two webs of the blade, one end of the second fixing plate 302 and the third fixing plate 303 are respectively vertically connected to the upper and lower parts of the first metal fixing plate 301, and the other ends are respectively oriented toward the blade tip direction and are respectively connected to the first metal fixing plate 301 by the first metal fixing plate 301. The fixed seat 307 and the third metal fixed seat 309 are fixed between the two webs. The two opposite sides of the second fixed plate 302 and the third fixed plate 303 are respectively formed with U-shaped slideways for the first mass block 304 and the second mass block 305 to slide. The first mass block 304 and the second mass block 305 are separated by a partition 306. The two ends of the partition 306 are respectively fixed between the two webs by the first metal fixed plate 301 and the second metal fixed seat 308. The second metal fixed seat 308 is located between the first metal fixed seat 307 and the third metal fixed seat 309. One end of the first mass block 304 and the second mass block 305 are respectively connected to the first metal fixed seat 307 and the third metal fixed seat 309 by four second springs 310. The first metal fixing seat 307 is connected to a metal fixing plate 301, and the other end is connected to the first metal slider 311 and the second metal slider 312 through four second springs 310 respectively; the bottom surface of the first metal fixing seat 307 and the top surface of the second metal fixing seat 308 are provided with two first metal plates 313 arranged in parallel to each other, and the opposite sides of the two first metal plates 313 are formed with slideways for the first metal slider 311 to slide; the bottom surface of the second metal fixing seat 308 and the top surface of the third metal fixing seat 309 are provided with two second metal plates 314 arranged in parallel to each other, and the opposite sides of the two second metal plates 314 are formed with slideways for the second metal slider 312 to slide; the first metal slider 311 is connected to the first metal fixing seat 307 and the second metal fixing seat 308 through four second springs 310 respectively; the bottom surface of the first metal fixing seat 307 and the top surface of the second metal fixing seat 308 are provided with two second metal plates 314 arranged in parallel to each other, and the opposite sides of the two second metal plates 314 are formed with slideways for the second metal slider 312 to slide; the first metal slider 311 is connected to the first metal fixing seat 307 through four second springs 310 The unit is connected to the first electromagnetic damping unit. The first metal slider 311 can slide along the slide of the two first metal plates 313 under the action of the first transmission unit. The first damping structure for dissipating the vibration energy from the blade tip swing is formed by the first mass block 304, the first metal slider 311 and the corresponding second spring 310. The second metal slider 312 is connected to the second electromagnetic damping unit through the second transmission unit. The second metal slider 312 can slide along the slide of the two second metal plates 314 under the action of the second transmission unit. The second damping structure for dissipating the vibration energy from the blade tip swing is formed by the second mass block 305, the second metal slider 312 and the corresponding second spring 310.

[0030] In this embodiment, by using a partition to separate the two mass blocks, two layers of damping structures are respectively formed. The two mass blocks slide in their respective U-shaped chutes. This not only ensures that the mass blocks slide in their respective designated sliding directions, but also ensures the decoupling of the vibrations in the flapping and pitching directions, avoids the coupling effect between the flapping and pitching directions, and can achieve vibration reduction without interference. At the same time, through the design of the chutes on the two metal plates, the two metal sliders only slide reciprocally in a horizontal direction, so that the two mass blocks are only affected by horizontal forces, avoiding the generation of non-horizontal forces on the springs and mass blocks due to changes in the motion state during the movement process, and reducing the damping effect of the tuned mass damper unit 3.

[0031] Preferably, the second spring can be any spring with good damping performance such as a corrugated spring, an annular spring or a butterfly spring.

[0032] Preferably, both the first mass block and the second mass block are of metal structure or magnetic body structure, and their weights are appropriately adjusted according to actual weight reduction, load reduction and cost requirements.

[0033] Preferably, both the second fixing plate and the third fixing plate are of metal structure or magnetic body structure.

[0034] Preferably, when the tuned mass damper unit is installed near the maximum chord length of the blade, its function can be maximally exerted.

[0035] Due to the flow separation on the blade airfoil surface, the blade will generate large-amplitude vibrations under the action of periodic aerodynamic forces. When the blade undergoes large-amplitude vibrations, the electromagnetic damping unit transfers a large amount of tip deformation energy to the tuned mass damper unit through the transmission unit. The two layers of damping structures inside the tuned mass damper unit respectively control the vibration energy transmitted from the tip flapping and pitching. The specific principle is as follows: The vibration energy transmitted from the tip flapping is applied to the first metal slider through the steel wire rope. The first metal slider slides and drives the stretching and contraction of the corresponding second spring, and then the first mass block makes reciprocating vibrations under the action of the spring. At this time, the energy is converted back and forth between elastic potential energy and mechanical energy, thereby eliminating the vibration energy transmitted from the tip flapping; at the same time, the vibration energy transmitted from the tip pitching is applied to the second metal slider through the steel wire rope. The second metal slider slides and drives the stretching and contraction of the corresponding second spring, so that the second mass block makes reciprocating vibrations under the action of the spring. At this time, the energy is also converted back and forth between elastic potential energy and mechanical energy, thereby eliminating the vibration energy transmitted from the tip pitching, and finally dissipating the deformation energy from the tip.

[0036] In summary, the damping system of the present invention is bidirectional energy-consuming, can minimize the deformation of the blade tip to the greatest extent, increase the blade life while reducing the risk of aeroelastic instability of the blade.

[0037] The above-described embodiments are only the preferred embodiments of the present invention, and do not limit the scope of implementation of the present invention. Therefore, any changes made according to the shape and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A vibration damping system for a wind turbine blade, characterized in that: It includes a plurality of shock absorption devices which are uniformly arranged inside the blade along the direction perpendicular to the chord of the blade; each shock absorption device includes two electromagnetic damping units, two transmission units and a tuned mass damper unit. The two electromagnetic damping units are respectively the first electromagnetic damping unit and the second electromagnetic damping unit. The first electromagnetic damping unit is arranged at the leading edge position of the blade tip, and the second electromagnetic damping unit is arranged at the PS surface or SS surface position of the blade tip. The metal sliders in the two electromagnetic damping units slide under the action of inertial force, and drive the metal coils therein to cut the magnetic induction lines in the magnetic field, so that a part of the vibration energy from the blade tip flapping and waving is dissipated in the form of heat. The two transmission units are respectively the first transmission unit and the second transmission unit. One ends of the first transmission unit and the second transmission unit are respectively connected to the first electromagnetic damping unit and the second electromagnetic damping unit; the tuned mass damper unit is arranged at the blade mid-span position and is located between the two webs of the blade. It is a double-layer damping structure, and the double-layer damping structure is respectively connected to the other ends of the first transmission unit and the second transmission unit. The vibration energy from the blade tip flapping and the vibration energy from the blade tip waving are respectively transmitted to the double-layer damping structure through the two transmission units and dissipated, so as to achieve the purpose of reducing the blade vibration. Among them, the tuned mass damper unit includes a first metal fixing plate, a second fixing plate, a third fixing plate, a first mass block, a second mass block, a partition plate, a first metal fixing seat, a second metal fixing seat, a third metal fixing seat, a second spring, a first metal slider, a second metal slider, a first metal plate and a second metal plate. The first metal fixing plate is fixed between the two webs of the blade. One ends of the second fixing plate and the third fixing plate are respectively vertically connected to the upper part and the lower part of the first metal fixing plate, and the other ends respectively face the blade tip direction and are respectively fixed between the two webs through the first metal fixing seat and the third metal fixing seat. U-shaped slides for the first mass block and the second mass block to slide are respectively formed on two opposite side surfaces of the second fixing plate and the third fixing plate. The first mass block and the second mass block are separated by a partition plate. Two ends of the partition plate are respectively fixed between the two webs through the first metal fixing plate and the second metal fixing seat, and the second metal fixing seat is located between the first metal fixing seat and the third metal fixing seat. One ends of the first mass block and the second mass block are respectively connected to the first metal fixing plate through a plurality of second springs, and the other ends are respectively connected to the first metal slider and the second metal slider through a plurality of second springs;Two first metal plates arranged in parallel to each other are provided on the bottom surface of the first metal fixing seat and the top surface of the second metal fixing seat, and slideways for the first metal slider to slide are formed on the opposite sides of the two first metal plates; two second metal plates arranged in parallel to each other are provided on the bottom surface of the second metal fixing seat and the top surface of the third metal fixing seat, and slideways for the second metal slider to slide are formed on the opposite sides of the two second metal plates; the first metal slider is connected to the first electromagnetic damping unit through the first transmission unit, and the first mass block, the first metal slider and the corresponding second spring form a first layer of damping structure for dissipating the vibration energy from the blade tip swinging; the second metal slider is connected to the second electromagnetic damping unit through the second transmission unit, and the second mass block, the second metal slider and the corresponding second spring form a second layer of damping structure for dissipating the vibration energy from the blade tip swinging. ; 2. The vibration damping system for a wind turbine blade according to claim 1, characterized in that: The electromagnetic damping unit includes a connection base, an N magnetic pole, an S magnetic pole, a metal fixing block, a metal slider, a metal coil and a first spring. The connection base is fixed at the leading edge, PS surface or SS surface position of the blade tip, and a groove for installing the N magnetic pole, S magnetic pole, metal fixing block, metal slider, metal coil and first spring is formed thereon. The N magnetic pole and the S magnetic pole are respectively fixed on both inner sides of the groove. The metal fixing block is fixed at the bottom of the groove and is located between the N magnetic pole and the S magnetic pole. The metal slider is slidably installed at the notch of the groove and is located between the N magnetic pole and the S magnetic pole, and is connected to the first transmission unit or the second transmission unit. The metal coil is arranged between the N magnetic pole and the S magnetic pole and is located between the metal slider and the metal fixing block, and its two ends are respectively connected to the metal fixing block and the metal slider by the first spring.

3. The vibration damping system for a wind turbine blade according to claim 2, characterized in that: The first spring is a corrugated spring, an annular spring or a butterfly spring.

4. The vibration damping system for a wind turbine blade according to claim 1, characterized in that: The second spring is a corrugated spring, an annular spring or a butterfly spring.

5. The vibration damping system for a wind turbine blade according to claim 1, characterized in that: Both the first mass block and the second mass block are of a metal structure or a magnetic body structure.

6. The vibration damping system for a wind turbine blade according to claim 1, characterized in that: Both the second fixing plate and the third fixing plate are of a metal structure or a magnetic body structure.

7. The vibration damping system for a wind turbine blade according to claim 1, characterized in that: The transmission unit includes a pulley bracket, a pulley and a steel wire rope. The pulley bracket is fixed inside the blade in a direction perpendicular to the chord of the blade and is located between the blade middle and the blade tip. A pulley is slidably installed on the pulley bracket. One end of the steel wire rope is connected to the first metal slider or the second metal slider of the tuned mass damper unit, and the other end bypasses the pulley and is connected to the first electromagnetic damping unit or the second electromagnetic damping unit.

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