A wind turbine blade vibration absorber based on quasi-zero stiffness

Abstract

The application discloses a wind turbine blade vibration absorber based on quasi-zero stiffness, and belongs to the technical field of vibration control of large wind turbine blades. The wind turbine blade vibration absorber comprises a plurality of parallel quasi-zero stiffness mechanisms, the quasi-zero stiffness mechanisms are connected between wind turbine blade main beams through a plurality of cables, and the quasi-zero stiffness mechanisms and the wind turbine blade main beams are arranged in an inclined mode to form a vibration suppression array. The quasi-zero stiffness mechanism comprises a positive stiffness structure and a negative stiffness structure which are arranged in parallel. The positive stiffness structure comprises a coil spring, and the coil spring is used for providing positive stiffness. The negative stiffness structure comprises an air spring, and the air spring is used for providing negative stiffness. The wind turbine blade vibration absorber based on quasi-zero stiffness is adopted, quasi-zero stiffness is realized through parallel connection of the air spring and the coil spring, vibration control of low frequency or even ultra-low frequency of the blade is realized through reduction of the stiffness of the vibration absorber, and the vibration absorber is light in weight and high in reliability.

Description

Technical Field

[0001] This invention relates to the field of vibration control technology for large wind turbine blades, and specifically to a wind turbine blade vibration absorber based on quasi-zero stiffness. Background Technology

[0002] Clean energy is a topic of great global concern today, and wind energy, with its outstanding advantages such as renewability, cleanliness, low cost, versatility, and compatibility with other resources, has become one of the most widely developed and applied renewable energy sources, demonstrating a promising development trend. However, as wind turbines become larger and lighter, a key technological challenge is becoming increasingly prominent: blade vibration control. Blade vibration not only affects the normal operation of the wind turbine, leading to reduced output power and aerodynamic noise, but can also cause catastrophic damage to the blade structure, threatening the safe operation of the entire unit.

[0003] Extensive research has been conducted by scholars both domestically and internationally on the vibration control of wind turbine blades. The technical approaches can be broadly categorized into passive and active methods. Active vibration control methods often employ advanced feedback control strategies. This approach requires integrating a series of complex devices into the wind turbine system, including state sensors, active controllers, and actuators. While active control theoretically achieves more precise and efficient vibration suppression, the trade-off is a dramatic increase in system complexity, resulting in high manufacturing and maintenance costs, as well as the potential risk of electronic component failure, ultimately leading to a decrease in the reliability of the wind turbine system.

[0004] Passive vibration control technology attempts to improve the coupling relationship between aerodynamic forces, inertial forces, and elastic forces in wind turbine blades at the structural and material levels, thereby reducing vibration. Specific technologies include blade structure optimization, the application of tuned mass dampers, and composite material coatings. Blade structure optimization improves stiffness and natural frequencies by altering blade geometry, thickness distribution, or internal stiffener layout to avoid the primary excitation frequency. This method enhances structural stability to some extent, but often results in significant blade weight increase and has limited effectiveness in suppressing low-frequency vibrations. Tuned mass dampers involve installing a mass-spring-damping system inside the blade, adjusting its natural frequency to match the blade's vibration frequency to achieve energy transfer and dissipation. While this method effectively suppresses vibrations at specific frequencies, it still requires a large additional mass and has a narrow vibration control bandwidth, making it difficult to adapt to complex operating conditions. Composite material coatings involve coating the blade surface with a composite material with high damping characteristics, dissipating vibration energy through the material's internal friction mechanism. Although this method is lightweight and easy to implement, its damping effect is limited, especially in the low-frequency range, and its long-term environmental adaptability needs to be verified.

[0005] In existing large wind turbine blade vibration control technologies, active control schemes are complex, costly, and lack reliability; while passive control schemes offer good reliability, they suffer from a core contradiction: the difficulty in simultaneously achieving lightweight design and low-frequency vibration suppression (the trend towards larger blades lowers their vibration frequencies, but low-frequency vibrations require increased vibration absorber mass for reduction, which conflicts with the goal of lightweight blade design). Therefore, overcoming this technical contradiction between lightweight design and low-frequency vibration control, and developing vibration absorbers that are lightweight, adaptable to low-frequency conditions, simple in structure, and highly reliable, has become a pressing technical challenge in the field of large wind turbine blade vibration control. Summary of the Invention

[0006] The purpose of this invention is to provide a wind turbine blade vibration absorber based on quasi-zero stiffness. Quasi-zero stiffness is achieved by connecting air springs and helical springs in parallel. By reducing the stiffness of the absorber, low-frequency or even ultra-low-frequency vibration control of the blade is achieved. It is lightweight and highly reliable.

[0007] To achieve the above objectives, the present invention provides a wind turbine blade vibration absorber based on quasi-zero stiffness, comprising several parallel quasi-zero stiffness mechanisms, which are respectively connected between the main beams of the wind turbine blade by cables, and the several quasi-zero stiffness mechanisms and the main beams of the wind turbine blade are inclined to form a vibration damping array.

[0008] The quasi-zero stiffness mechanism includes a positive stiffness structure and a negative stiffness structure arranged in parallel. The positive stiffness structure includes a helical spring, which is used to provide positive stiffness, and the negative stiffness structure includes an air spring, which is used to provide negative stiffness.

[0009] Preferably, the outer cover of the helical spring is provided with an outer shell, one end of the helical spring is connected to the outer shell by a ring buckle, and the outer shell is connected to the main beam of the wind turbine blade by the ring buckle.

[0010] Preferably, the other end of the helical spring is connected to one end of the connecting block via a ring buckle, the other end of the connecting block is connected to one end of the cable via a ring buckle, and the other end of the cable is connected to the main beam of the wind turbine blade.

[0011] Preferably, the connecting block is provided with an inner spring support, which is connected to the inner roller via an air spring.

[0012] Preferably, the inner roller is connected to the outer roller located outside the air spring.

[0013] Preferably, the inner roller is fitted in the middle of the air spring, and the two ends of the air spring are pressed and secured to the two ends of the inner support of the spring by spring lock rings.

[0014] Preferably, the outer roller is connected to the housing via threads.

[0015] Preferably, the helical spring is suspended inside the housing.

[0016] Preferably, the air spring is located inside the housing.

[0017] Preferably, a rope locking device is provided at the end where the cable connects to the connecting block.

[0018] The present invention provides a quasi-zero stiffness wind turbine blade vibration absorber with the above-described structure, which has the following beneficial effects:

[0019] 1. The present invention uses a quasi-zero stiffness mechanism formed by air springs and helical springs in parallel to significantly reduce the stiffness of the vibration absorber, adapt to the ultra-low vibration frequency of large wind turbine blades, and achieve low-frequency and wide-band vibration absorption effect.

[0020] 2. This invention is based on quasi-zero stiffness, which greatly reduces the stiffness of the vibration absorber and solves the problem that traditional vibration absorbers cannot achieve both low natural frequency and lightweight design. Compared with linear vibration absorbers, quasi-zero stiffness vibration absorbers are lighter, which fits the lightweight design principle of blades.

[0021] 3. This invention adopts a fully mechanical structure design, which fundamentally reduces the risk of electronic component failure in the active vibration absorber. After the device is installed in the internal cavity of the blade, no manual intervention is required, resulting in low maintenance costs.

[0022] 4. This invention is mainly composed of standardized, low-cost components such as springs, air springs, and tensioning wires. The overall cost is low, the manufacturing process is relatively simple, and it is easy to standardize production and large-scale installation.

[0023] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention;

[0025] Figure 2 This is a cross-sectional view of a quasi-zero stiffness mechanism according to an embodiment of the present invention;

[0026] Figure 3 This is a diagram showing the motion of the vibration absorber and the force on the air spring according to an embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram of the negative stiffness structure assembly of the air spring of the present invention.

[0028] Figure Labels

[0029] 1. Ring buckle; 2. Outer shell; 3. Helical spring; 4. Connecting block; 5. Spring lock ring; 6. Air spring; 7. Inner roller; 8. Spring inner support; 9. Outer roller; 10. Cable; 11. Rope locker. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages disclosed in the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the embodiments of the present invention and are not intended to limit the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments in this application without creative effort are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.

[0031] It should be noted that the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or server that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such processes, methods, products, or devices.

[0032] Similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0033] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed when in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0034] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] Example

[0036] like Figure 1As shown, the wind turbine blade vibration absorber based on quasi-zero stiffness of the present invention includes several parallel quasi-zero stiffness mechanisms, which are respectively connected between the main beams of the wind turbine blade by cables 10. One end of the cable 10 is fixed to the lower inner surface of the blade, and the other end is connected to the connecting block 4 in the quasi-zero stiffness mechanism; the quasi-zero stiffness mechanism is fixed to the upper inner surface of the blade, and the whole is periodically distributed in the blade cavity at a specific tilt angle to form a vibration damping array.

[0037] like Figure 2 As shown, the quasi-zero stiffness mechanism consists of a core mechanical unit comprised of a helical spring 3 and an air spring 6. The quasi-zero stiffness mechanism includes a parallel positive stiffness structure and a negative stiffness structure. The positive stiffness structure includes the helical spring 3, which provides positive stiffness, while the negative stiffness structure includes the air spring 6, which provides negative stiffness. The helical spring 3 is enclosed by a housing 2, with one end connected to the housing 2 via a ring 1. A threaded hole runs through the upper part of the housing 2, and the uppermost end is connected to the ring 1 via a thread, allowing it to be suspended from the main beam of the wind turbine blade. Another ring 1 is connected to the lower end of the threaded hole, suspending the helical spring 3. The lower end of the helical spring 3 is also connected to a ring 1, which is threaded to one end of a connecting block 4. The other end of the connecting block 4 is connected to one end of a cable 10 via a ring 1, and the other end of the cable 10 is connected to the main beam of the wind turbine blade. An inner spring support 8 is provided on the connecting block 4, and the inner spring support 8 is connected to an inner roller 7 via an air spring 6. The inner roller 7 is fitted in the middle of the air spring 6, and the two ends of the air spring 6 are pressed and secured to the two ends of the inner support 8 by the spring lock ring 5. The inner roller 7 is connected to the outer roller 9 located outside the air spring 6. The helical spring 3 is suspended inside the outer shell 2, and the air spring 6 is located inside the outer shell 2. A rope locking device 11 is provided at the end of the cable 10 that is connected to the connecting block 4.

[0038] like Figure 4 As shown, the air spring 6, spring lock ring 5, inner spring support 8, inner roller 7, etc., form a negative stiffness structure assembly, which is connected to the external thread of the connecting block 4 through the internal thread of the inner spring support 8. The lower end of the outer shell 2 has an internal thread, which allows the outer roller 9 to be connected to it through the thread. The lower end of the connecting block 4 is connected to the ring buckle 1 through the thread, and the lower end is used to suspend the cable 10.

[0039] The core working principle of this invention is based on quasi-zero stiffness characteristics. For example... Figure 3As shown, at the static equilibrium position, through precise design of the initial length of the helical spring 3 and the internal pressure of the air spring 6, the helical spring 3 is in a stretched state, the air spring 6 is in a compressed state, and the inner roller 7 and the outer roller 9 are precisely aligned. At this time, the forces exerted by the outer roller 9 on the air spring 6 are equal in magnitude and opposite in direction, thus canceling each other out. This results in the air spring 6 exerting no force on the cable 10, and the tension of the cable 10 cancels out the tension of the helical spring 3. When the lateral vibration of the cable 10 causes the quasi-zero device and the connection end of the cable 10 to move downward, the helical spring 3 further extends, providing a greater spring force to resist the downward movement and provide positive stiffness; the air spring 6 moves downward, and the force exerted by the outer roller 9 on it is obliquely downward. The horizontal components of these forces cancel each other out, leaving only the downward component, which promotes the downward movement and thus provides negative stiffness. Conversely, when the connecting end moves upward, the helical spring 3 shortens, resisting the upward movement and providing positive stiffness; while the air spring 6 moves upward, the component of the force exerted on it by the outer roller 9 is upward, promoting its upward movement and providing negative stiffness.

[0040] The vibration frequency of large wind turbine blades is typically low. By appropriately setting the preload of the cable 10 and the spring stiffness of the quasi-zero vibration absorber, the vibration absorber unit is set to a low frequency that matches the wind turbine blade. When the wind turbine blade vibrates, the vibration energy is transferred to the cable 10 and the quasi-zero vibration absorber, causing them to undergo forced vibration. This transfers the vibration energy from the wind turbine blade to the vibration absorber, thereby suppressing the vibration. To cope with the large surface area and complex vibration modes of large wind turbine blades, a single vibration absorber unit is often insufficient. Therefore, this invention proposes to periodically distribute multiple quasi-zero stiffness vibration absorber units with a certain span within the cavity structure inside the blade, forming a quasi-zero stiffness vibration absorption array.

[0041] like Figure 1 As shown, the present invention is based on a specific tilt angle. It is non-orthogonal to the inner surface of the blade, in which It is the lower limit of the tilt angle, which is 0°. This is the upper limit of the tilt angle, which is 90°. This tilt angle... The spatial dimensions of the device and the spacing of the array. All designs must be precisely executed through dynamic modeling and iterative optimization, based on key parameters such as the critical vibration velocity, natural frequency, and material density of the target blade. This periodic array layout can create bandgap characteristics, effectively suppressing vibrations in specific frequency bands. Furthermore, the synergistic effect of multiple units enhances the overall reliability of the vibration suppression system.

[0042] Therefore, the present invention adopts a wind turbine blade vibration absorber based on quasi-zero stiffness, which achieves quasi-zero stiffness by connecting air spring 6 and helical spring 3 in parallel. By reducing the stiffness of the vibration absorber, the vibration control of the blade at low frequency or even ultra-low frequency is achieved, resulting in good lightweight and high reliability.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A wind turbine blade vibration absorber based on quasi-zero stiffness, characterized in that: It includes several parallel quasi-zero stiffness mechanisms, which are respectively connected between the main beams of the wind turbine blades via cables. The quasi-zero stiffness mechanisms and the main beams of the wind turbine blades are inclined to form a vibration damping array. The quasi-zero stiffness mechanism includes a positive stiffness structure and a negative stiffness structure arranged in parallel. The positive stiffness structure includes a helical spring, which is used to provide positive stiffness, and the negative stiffness structure includes an air spring, which is used to provide negative stiffness. The outer cover of the helical spring is equipped with an outer shell, one end of the helical spring is connected to the outer shell by a ring buckle, and the outer shell is connected to the main beam of the wind turbine blade by the ring buckle; The other end of the helical spring is connected to one end of the connecting block via a ring buckle, the other end of the connecting block is connected to one end of the cable via a ring buckle, and the other end of the cable is connected to the main beam of the wind turbine blade. The connecting block is equipped with an inner spring support, which is connected to the inner roller via an air spring. The inner roller is connected to the outer roller located outside the air spring; The inner roller is fitted in the middle of the air spring, and the two ends of the air spring are pressed and fixed to the two ends of the inner support of the spring by the spring lock ring; The outer rollers are connected to the housing via threads.

2. The wind turbine blade vibration absorber based on quasi-zero stiffness according to claim 1, characterized in that: The helical spring is suspended inside the casing.

3. The wind turbine blade vibration absorber based on quasi-zero stiffness according to claim 2, characterized in that: The air spring is located inside the housing.

4. The wind turbine blade vibration absorber based on quasi-zero stiffness according to claim 1, characterized in that: A rope locking device is provided at the end where the cable connects to the connecting block.

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