Blade micro-amplitude high-frequency vibration suppression device, system and method based on multi-wire SMA

Abstract

The invention discloses a multi-wire SMA-based blade micro-amplitude high-frequency vibration suppression device, system and method, the device comprises a blade, the blade comprises a closed main body structure and an outer coating mechanism, the closed main body structure is connected with an inner control mechanism and an induction mechanism, and the outer coating mechanism comprises a filler layer and a skin shell which are arranged outside the closed main body structure; the inner control mechanism comprises a plurality of shape memory alloy wires, an arc head, an air bellow, a power-on pile, a spring and a spring seat. According to the system, hidden faults such as cracks in blade tissues caused by the blade in a long-term micro-high vibration state can be avoided, vibration can be accurately eliminated or weakened through adjustment of the system when micro-high vibration continuously occurs, meanwhile, the whole blade structure and the whole suppression device can be better protected, and the service life of the blade is prolonged. The use stability and the service life of the whole blade are improved, and the later maintenance frequency is reduced.

Description

Technical Field

[0001] This invention relates to the field of wind turbine structural safety or motion control, specifically to a blade micro-amplitude high-frequency vibration suppression device, system, and method based on multi-wire SMA. Background Technology

[0002] To improve wind power generation efficiency, wind turbines are trending towards larger sizes. Designing high-quality, large blades is a challenging task, thus necessitating research into the fracture failure problem of large and medium-sized wind turbine blades. The destructive fracture phenomena of large wind turbine blades that have occurred worldwide in recent years, particularly along coastal areas, underscore the necessity of this research. To date, existing research has generally focused on the nonlinear aeroelastic stability of blades during stall, linear classical flutter under high wind speeds, and fracture failure caused by vibrations under various turbulent and wake effects.

[0003] In practice, it has been found that a wind turbine operating under "normal conditions" will exhibit a certain micro-amplitude high-frequency vibration phenomenon when its excitation frequency is close to a certain high-order (3rd-5th order) natural frequency. Due to the long-term exposure of the blades to nonlinear micro-amplitude high-frequency vibration conditions, latent crack defects will form in the composite blades. These latent crack defects include structural defects such as cracking, delamination, and debonding within the skin structure, or misalignment of the filler within the skin shell structure.

[0004] This latent defect makes the blades more prone to overt fracture failure and longitudinal cracking of the main beam under high-wind-speed flutter conditions or extreme operating conditions (latent fracture failure, the crack location can only be seen during disassembly and maintenance). Furthermore, for small wind turbines, this latent crack defect located near high-stress areas often shortens the blade's lifespan. Even under small-scale turbulent wind conditions, the high-frequency effects of aerodynamic loads and equivalent fatigue loads caused by turbulent winds can result in small-amplitude, high-frequency vibrations in the flapping direction.

[0005] Therefore, given the complexity and high cost of manufacturing wind turbine blades, prevention is far more effective than repairing damaged blades and implementing further structural performance enhancements, and it can significantly reduce the development and maintenance costs of blades. Thus, developing a micro-amplitude high-frequency (micro-high) vibration suppression system for wind turbine blades based on multi-wire SMA has both engineering practical significance and economic value in the field of structural safety and motion control of wind turbine blades. Summary of the Invention

[0006] The purpose of this invention is to provide a blade micro-amplitude high-frequency vibration suppression device based on multi-filament SMA, which can be used to solve the problem of blade micro-amplitude high-frequency vibration.

[0007] A blade micro-amplitude high-frequency vibration suppression device based on multi-filament SMA includes a blade, the blade includes a closed main body structure and an outer covering mechanism, the closed main body structure is connected to an internal control mechanism and a sensing mechanism, and the outer covering mechanism includes a filler layer and a skin shell disposed outside the closed main body structure;

[0008] The internal control mechanism includes multiple shape memory alloy wires, an arc head, a bellows, a power supply stake, a spring, and a spring seat. The arc head is located inside the upper part of the closed main structure, and the power supply stake is installed inside the lower part of the closed main structure and is connected to the power supply stake via an electric wire.

[0009] Multiple shape memory alloy wires independently pass around the arc head. The two ends of each shape memory alloy wire go downward through the horizontal surface of the power supply pile and connect to the spring seat set inside the power supply pile. The spring is sleeved on the outside of the shape memory alloy wire and fixed on the spring seat. The two ends of each shape memory alloy wire are respectively connected to the positive and negative terminals of the power supply pile. The shape memory alloy wire is constrained and positioned by several buckles on the inner wall of the closed main structure.

[0010] The bellows is located inside the closed main structure above the electrified pile. Ventilation holes are opened on the inner wall of the upper cavity of the closed main structure facing the upper edge (or leading edge) of the blade. The ventilation holes pass through the thin wall of the closed main structure and extend downwards to the bottom of the closed main structure, closely following the center line of the thin wall.

[0011] The sensing mechanism includes a piezoelectric pickup located at the top of the closed main structure and an infrared thermometer located on the inner wall of the middle of the closed main structure.

[0012] Preferably, the closed main structure is a thin-walled shell structure made of composite material, the cross-sectional shape of the closed main structure is frustum-shaped, and the width of the upper part of the closed main structure near the leading edge of the airfoil is greater than the width of the lower part of the closed main structure.

[0013] Each surface of the outer surface of the closed main structure is a plane, used to support the honeycomb-shaped filler layer, and the outermost edge of the filler layer is a skin shell structure.

[0014] Each surface of the inner surface of the closed main structure is also a plane, used for installing the arc head, bellows, power supply pile, and clips;

[0015] The closed main structure extends through the leaf root, and the distance from the top of the closed main structure to the leaf tip is approximately 1 / 7 to 1 / 6 of the total length of the leaf.

[0016] Preferably, the shape memory alloy wires are arranged at independent intervals;

[0017] The electrified pile is in the shape of an inverted U-shaped plate, and its two side walls are fixedly connected to the inner surface of the closed main structure by bolts.

[0018] Preferably, the bellows is an independent structure, and a fan is installed inside the bellows. The fan is a fixed-frequency fan or a variable-frequency fan. The bellows is installed near the blade root, at a position one-third of the total blade length. An infrared thermometer is connected to the fan via a circuit.

[0019] Preferably, the arc head is composed of a lower positioning block and an upper arc-shaped block, both of which are made of insulating material, and a plurality of parallel alloy wire limiting grooves are formed on the outer surface of the arc head.

[0020] Preferably, when the number of shape memory alloy wires is 2-5, it is used in the blades of small and medium-sized wind turbines; when the number of shape memory alloy wires is greater than 5, it is used in the blades of large wind turbines.

[0021] The spring is a circular spring made of lightweight and tough material. One end of the spring is fixed to a flat cylindrical spring seat, and the other end of the spring is connected to the lower end face of the energized stake. A shape memory alloy wire passes through the spring, and the diameter of the shape memory alloy wire is 0.31mm-1.1mm.

[0022] Another objective of this invention is to provide a blade micro-amplitude high-frequency vibration suppression system based on multi-filament SMA.

[0023] To achieve the above objectives, the technical solution adopted by this invention is as follows:

[0024] A blade micro-amplitude high-frequency vibration suppression system based on multi-filament SMA, employing the aforementioned blade micro-amplitude high-frequency vibration suppression device based on multi-filament SMA, wherein the blade micro-amplitude high-frequency vibration suppression device based on multi-filament SMA is used in at least one blade in a wind turbine.

[0025] The blade micro-amplitude high-frequency vibration suppression system also includes a PLC control system installed inside the wind turbine and a wind speed sensor installed on the blade or the outer surface of the wind turbine. The PLC control system is connected to the main power supply of the wind turbine through a line; the PLC control system is also connected to the internal control mechanism, the sensing mechanism, and the wind speed sensor through a line.

[0026] Another objective of this invention is to provide a method for suppressing micro-amplitude high-frequency vibrations of blades.

[0027] To achieve the above objectives, the technical solution adopted by this invention is as follows:

[0028] A method for suppressing micro-amplitude high-frequency vibration of wind turbine blades, employing the aforementioned multi-wire SMA-based micro-amplitude high-frequency vibration suppression system, includes the following steps:

[0029] S1. After the system starts, the PLC control system is powered on, and the sensors in the corresponding internal control mechanism and sensing mechanism are powered on; the piezoelectric vibration pickup enters the vibration detection mode, the infrared thermometer enters the temperature detection mode, and the wind speed sensor enters the external wind speed detection mode.

[0030] S2: When the piezoelectric vibration pickup detects a signal with a vibration amplitude of no more than 2 mm and a vibration frequency of 5-25 Hz, if the signal lasts for more than 5 minutes, it is considered that the blade system has experienced continuous micro-high vibration under normal operating conditions, and then S3 is executed; otherwise, the vibration detection mode is maintained.

[0031] S3, when the power supply is connected to the energized pile, the current passes through the shape memory alloy wire SMA. The SMA temperature rises and begins to contract, which on the one hand tightens the arc head, and on the other hand, the two wires of SMA pull the spring seat to move towards the bottom of the energized pile.

[0032] S4, as the temperature further increases, the SMA wire continues to shorten, and the spring and spring seat continue to compress until the spring seat is tightly pressed. If the vibration continues to decay, it will disappear when a certain temperature t0 is reached, then S5 is executed; if the maximum allowable temperature t of the SMA is reached... max If the micro-vibration has not completely disappeared, then execute S9;

[0033] S5, turn on the bellows. The airflow enters from the inside of the closed main structure at the blade root. The airflow goes around the two ends of the electrified pile from the side and goes up along the cavity of the closed main structure. After going around the arc head, it goes out through the small diameter hole on the side wall of the closed main structure and flows down and out through the hole on the outside of the closed main structure.

[0034] S6, the infrared thermometer detects and reads the temperature inside the closed main structure in real time, and feeds it back to the PLC controller in the PLC control system. The PLC controller controls the power supply of SMA and fan to alternately turn on and off, so that the temperature fluctuates around t0 and maintains a state of vibration elimination.

[0035] S6, until the wind speed sensor detects a significant change in wind conditions, at which point the blade structure has avoided the flutter area. At this point, the PLC controller issues a command to disconnect the power supply, the SMA gradually cools down, and the length elongates and recovers. At this point, the micro-high vibration has completely disappeared.

[0036] S8 is controlled by a PID control module to achieve the desired result at t max The precise temperature control helps to suppress micro-vibrations; although the vibration has not completely disappeared, it has been reduced to a sufficiently safe level, and the PID control module can protect the SMA wire.

[0037] Similarly, S9, until the wind speed sensor detects a significant change in wind conditions, the blade structure avoids the flutter area and there is no need to continue the constant temperature control of the PID control module; at this time, the PLC controller issues a command to disconnect the power supply, the SMA filament gradually cools down, and the length elongation is restored.

[0038] Preferably, the control method within the PID control module uses either a digital PID method or an analog PID method.

[0039] The digital PID method requires the CPU module in the PLC controller to output two switching signals, and then use PID calculation to output two pulse signals to control the power supply of the SMA wire and the fan to achieve the goal of constant temperature control.

[0040] The analog PID method requires the CPU module in the PLC controller to output an analog signal through the analog output module, which controls the frequency converter to further control the fan speed to achieve the goal of constant temperature control. At this time, the SMA power supply is always on.

[0041] Preferably, the maximum allowable temperature t in S4 for the SMA is... max It is the allowable temperature value at which the output performance of the selected SMA wire is minimized during repeated operation tests;

[0042] highest temperature t max The method for determining t is as follows: when the parameters of spring stiffness, number, length and diameter of SMA, and average wind force under normal working conditions are designed in accordance with the design plan of linear variable load actuator, t max The value t occurs when the spring is fully compressed for a period of time, and the SMA temperature rises to a certain value, at which the actuation output performance degradation is minimal. max .

[0043] To achieve the above objectives, the technical solution adopted by this invention is as follows:

[0044] The beneficial effects of this invention are:

[0045] The developed blade micro-amplitude high-frequency vibration suppression system based on multi-filament SMA can prevent latent failures such as internal cracks in the blade structure caused by long-term micro-high vibration. Although the negative effects of micro-high vibration are not significant in the short term, their long-term existence may cause latent failures in wind turbine units, including structural defects such as cracking, delamination, and debonding in the internal structure of the skin, or misalignment of the filler in the skin shell structure. These latent defects make the blade body more prone to obvious fracture failure and longitudinal cracking of the main beam under high wind speed flutter conditions or extreme operating conditions.

[0046] The bellows in this design is an independent component. It is large enough that its length and width almost occupy the entire cavity area of ​​the closed structure's cross-section to ensure that the airflow passing through the fan can be delivered as far as possible through the uppermost side opening. The fan installed in the bellows is a commercially available general-purpose fan, including both fixed-frequency and variable-frequency fans. If a fixed-frequency fan is used, the controller employs digital PID control for constant temperature control: it uses output switching pulse signals to control the power supply to the SMA wire and the fan, respectively, to achieve digital PID control. If a variable-frequency fan is used, the controller outputs analog signals to directly drive the inverter, using the inverter's output voltage to control the fan speed, directly achieving analog temperature control. In this case, there is no need to disconnect the SMA wire power supply, avoiding frequent switching of the SMA wire current and more effectively protecting it. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the main body and external structure of the blade composite material.

[0048] Figure 2 This is a schematic diagram of the blade.

[0049] Figure 3 This is a schematic diagram of the structural position of the arc head.

[0050] Figure 4 This is a schematic diagram showing the structural location of the ventilation opening (located at the leading edge).

[0051] Figure 5 This is a schematic diagram of the location of the electrified pile structure.

[0052] Figure 6 This is a schematic diagram of the bellows.

[0053] Figure 7 This is a diagram showing the location of the bellows.

[0054] Figure 8 This is a schematic diagram of the connection between the electrified pile and the spring.

[0055] Figure 9 This is a structural diagram of the arc head.

[0056] Figure 10 This is a flowchart illustrating the system implementation and control process of the method for suppressing micro-amplitude high-frequency vibration of blades. Detailed Implementation

[0057] The present invention will now be described in detail with reference to the accompanying drawings:

[0058] Example 1, combined with Figures 1 to 10 This embodiment discloses the following content:

[0059] A blade micro-amplitude high-frequency vibration suppression device based on multi-filament SMA includes a blade 1. The blade 1 includes a closed main structure 2 and an outer covering mechanism 3. The closed main structure 2 is connected to an internal control mechanism 4 and a sensing mechanism. The outer covering mechanism 3 includes a filler layer 31 and a skin shell 32 disposed outside the closed main structure 2.

[0060] The internal control mechanism 4 includes multiple shape memory alloy wires 41, an arc head 42, a bellows 43, a power supply post 44, a spring 45, and a spring seat 46. The arc head 42 is located in the upper part of the closed main body structure 2, and the power supply post 44 is installed in the lower part of the closed main body structure 2 and is connected to the power supply post 49 through an electric wire.

[0061] Multiple shape memory alloy wires 41 independently pass around the arc head 42. The two ends of each shape memory alloy wire 41 pass downward through the horizontal surface of the power supply pile 44 and connect to the spring seat 46 set inside the power supply pile 44. The spring 45 is sleeved on the outside of the shape memory alloy wire 41 and fixed on the spring seat 46. The two ends of each shape memory alloy wire 41 are respectively connected to the positive and negative terminals of the power supply 49 of the power supply pile. The shape memory alloy wire 41 is constrained and positioned by several buckles 47 on the inner wall of the closed main structure 2.

[0062] The bellows 43 is located inside the closed main structure 2 above the electrified pile. The upper cavity of the closed main structure 2 has ventilation holes 48 on its inner wall facing the upper edge (or leading edge) of the blade. The ventilation holes 48 pass through the thin wall of the closed main structure 2, and then extend down to the bottom of the closed main structure 2, close to the centerline of the thin wall of the closed main structure 2, and then exit.

[0063] The sensing mechanism includes a piezoelectric pickup located at the top of the closed main structure 2 and an infrared thermometer located on the inner wall of the middle part of the closed main structure.

[0064] Example 2, based on the above examples, further discloses the following:

[0065] The closed main structure 2 is a thin-walled shell structure made of composite material. The cross-sectional shape of the closed main structure 2 is frustum-shaped. The width of the upper part of the closed main structure 2 near the leading edge of the airfoil is greater than the width of the lower part of the closed main structure.

[0066] Each surface of the outer surface of the closed main structure 2 is a plane, used to support the honeycomb-shaped filler layer 31, and the outermost edge of the filler layer is a skin shell 32 structure; each surface of the inner surface of the closed main structure is also a plane, used to install the arc head 42, the bellows 43, the power supply pile 44, and the buckle 47.

[0067] The closed main structure 2 penetrates the root of the blade 1, and the distance between the top of the closed main structure 2 and the tip of the blade is about 1 / 7 to 1 / 6 of the total length of the blade 1.

[0068] The shape memory alloy wires 41 are arranged at independent intervals; the power-conducting piles 44 are in the shape of an inverted U-shape, and the two side walls of the power-conducting piles 44 are fixedly connected to the inner surface of the closed main structure 2 by bolts.

[0069] The bellows 43 is an independent structure, and a fan is installed inside the bellows 43. The fan is a fixed frequency fan or a variable frequency fan. The bellows 43 is installed near the blade root, and its installation point is at 1 / 3 of the total blade length. The infrared thermometer is connected to the fan through a line.

[0070] Example 3: Based on the above examples, this example further discloses the following:

[0071] The arc head 42 is composed of a lower positioning block 421 and an upper arc-shaped block 422. Both the lower positioning block 421 and the upper arc-shaped block 422 are made of insulating material. Several parallel alloy wire limiting grooves 423 are formed on the outer surface of the arc head 42.

[0072] When the number of shape memory alloy wires 41 is 2-5, it is used in the blades of small and medium-sized wind turbines; when the number of shape memory alloy wires 41 is greater than 5, it is used in the blades of large wind turbines.

[0073] The spring 45 is a circular spring made of lightweight and tough material. One end of the spring 45 is fixed on a flat cylindrical spring seat 46, and the other end of the spring 45 is connected to the lower end face of the energized post 44. The shape memory alloy wire 41 passes through the spring 45, and the diameter of the shape memory alloy wire 41 is 0.31mm-1.1mm.

[0074] In this application, the entire airflow channel from the vent is located at the upper or leading edge rather than the trailing edge because the upper or leading edge is relatively less prone to deformation, making it less likely to cause a destructive accident to the airflow channel. Furthermore, during blade fabrication, the channel can be positioned first by a flexible tube, then resin is poured in, and after the resin cools, a honeycomb filler layer is laid. The entire filler layer is quite thick, and the mechanical and mechanical properties are not reduced due to the opening of the vent. Since the resin pouring typically uses a vacuum infusion process, the inner wall of the formed vent can maintain sufficient strength and toughness for a long time even after the positioning flexible tube weathers and detaches.

[0075] As mentioned earlier, due to the complex and expensive manufacturing process of wind turbine blades, especially large and medium-sized wind turbine blades, prevention is far more cost-effective than repair measures and further structural reinforcement after blade damage. The suppression scheme proposed in this invention is a proactive solution to eliminate latent faults and prevent them from occurring in the first place.

[0076] Example 4: Based on the above examples, this example further discloses the following:

[0077] A blade micro-amplitude high-frequency vibration suppression system based on multi-filament SMA is disclosed, which employs the aforementioned blade micro-amplitude high-frequency vibration suppression device based on multi-filament SMA, wherein the multi-filament SMA-based blade micro-amplitude high-frequency vibration suppression device is used in at least one blade of a wind turbine.

[0078] The blade micro-amplitude high-frequency vibration suppression system also includes a PLC control system and a wind speed sensor. The PLC control system is connected to the internal control mechanism, sensing mechanism, and wind speed sensor via wiring.

[0079] Example 5: Based on the above examples, this example further discloses the following:

[0080] A method for suppressing micro-amplitude high-frequency vibration of blades, employing a multi-wire SMA-based blade micro-amplitude high-frequency vibration suppression system, includes the following steps:

[0081] S1. After the system starts, the PLC control system is powered on, and the sensors in the corresponding internal control mechanism and sensing mechanism are powered on; the piezoelectric vibration pickup enters the vibration detection mode, the infrared thermometer enters the temperature detection mode, and the wind speed sensor enters the external wind speed detection mode.

[0082] S2: When the piezoelectric vibration pickup detects a signal with a vibration amplitude of no more than 2 mm and a vibration frequency of 5-25 Hz, if the signal lasts for more than 5 minutes, it is considered that the blade system has experienced continuous micro-high vibration under normal operating conditions, and then S3 is executed; otherwise, the vibration detection mode is maintained.

[0083] S3, when the power supply is connected to the energized pile, the current passes through the shape memory alloy wire SMA. The SMA temperature rises and begins to contract, which on the one hand tightens the arc head, and on the other hand, the two wires of SMA pull the spring seat to move towards the bottom of the energized pile.

[0084] S4, as the temperature further increases, the SMA wire continues to shorten, and the spring and spring seat continue to compress until the spring seat is tightly pressed. If the vibration continues to decay, it will disappear when a certain temperature t0 is reached, then S5 is executed; if the maximum allowable temperature t of the SMA is reached... max If the micro-vibration has not completely disappeared, then execute S9;

[0085] S5, turn on the bellows. The airflow enters from the inside of the closed main structure at the blade root. The airflow goes around the two ends of the electrified pile from the side and goes up along the cavity of the closed main structure. After going around the arc head, it goes out through the small diameter hole on the side wall of the closed main structure and flows down and out through the hole on the outside of the closed main structure.

[0086] S6, the infrared thermometer detects and reads the temperature inside the closed main structure in real time, and feeds it back to the PLC controller in the PLC control system. The PLC controller controls the power supply of SMA and fan to alternately turn on and off, so that the temperature fluctuates around t0 and maintains a state of vibration elimination.

[0087] S6, until the wind speed sensor detects a significant change in wind conditions, at which point the blade structure has avoided the flutter area. At this point, the PLC controller issues a command to disconnect the power supply, the SMA gradually cools down, and the length elongates and recovers. At this point, the micro-high vibration has completely disappeared.

[0088] S8 is controlled by a PID control module to achieve the desired result at t max The precise temperature control helps to suppress micro-vibrations; although the vibration has not completely disappeared, it has been reduced to a sufficiently safe level, and the PID control module can protect the SMA wire.

[0089] Similarly, S9, until the wind speed sensor detects a significant change in wind conditions, the blade structure avoids the flutter area and there is no need to continue the constant temperature control of the PID control module; at this time, the PLC controller issues a command to disconnect the power supply, the SMA filament gradually cools down, and the length elongation is restored.

[0090] The control method within the PID control module can be either digital PID or analog PID.

[0091] The digital PID method requires the CPU module in the PLC controller to output two switching signals, and then use PID calculation to output two pulse signals to control the power supply of the SMA wire and the fan to achieve the goal of constant temperature control.

[0092] The analog PID method requires the CPU module in the PLC controller to output an analog signal through the analog output module, which controls the frequency converter to further control the fan speed to achieve the goal of constant temperature control. At this time, the SMA power supply is always on.

[0093] The maximum allowable temperature t in S4 SMA max It is the allowable temperature value at which the output performance of the selected SMA wire is minimized during repeated operation tests;

[0094] highest temperature t max The method for determining t is as follows: when the parameters of spring stiffness, number, length and diameter of SMA, and average wind force under normal working conditions are designed in accordance with the design plan of linear variable load actuator, t max The value t occurs when the spring is fully compressed for a period of time, and the SMA temperature rises to a certain value, at which the actuation output performance degradation is minimal. max .

[0095] Example 6: Based on the above examples, this example further discloses the following:

[0096] In a wind turbine installation area in western my country, given the complex and expensive manufacturing process of wind turbine blades, especially large and medium-sized ones, prevention is far more cost-effective than repairs and further structural reinforcement after blade damage. This invention proposes a blade micro-amplitude high-frequency (micro-high) vibration suppression system based on multi-filament SMA, which is a proactive solution to eliminate latent faults and prevent future damage.

[0097] The vibration damping system consists of two main parts: the composite material body of the blade and its external structure, and the internal components of the body. The blade body is a thin-walled closed structure of composite material, and its external structure includes a skin and filler layer; its internal components include multi-wire SMA, arc head, wind box, energizing post, spring seat (with spring), and clips.

[0098] The cross-sectional shape of the thin-walled closed structure is quasi-rectangular (the side near the airfoil leading edge has a slightly larger value). Every surface of the outer edge of the closed structure is flat, facilitating the support of the honeycomb packing layer; the outermost edge of the packing layer is a conventional skin structure. Every surface of the inner edge of the thin-walled closed structure is also flat, facilitating the arrangement and installation of the air intake, bellows, power supply pins, and clips. The length of the thin-walled closed structure extends through the blade root, and the distance from its top to the blade tip is approximately 1 / 7 to 1 / 6 of the total blade length. A piezoelectric vibration pickup is installed at the top of the thin-walled closed structure to detect vibration signals. When a vibration amplitude not exceeding 2 mm and a vibration frequency between 5 and 25 Hz is detected, if this signal persists for more than 5 minutes, it is considered that the blade system is experiencing continuous micro-to-high-frequency vibration under normal operating conditions.

[0099] Multi-wire SMA consists of multiple independent SMA metal wires, each independently wrapping around the arc end at the top of the closed structure. The two ends of each wire extend downwards, passing through the horizontal surface of the energized post. Each end connects to an independent spring seat. The spring, facing the energized post, is fitted onto the wire and secured to the spring seat. The two ends of each wire can be connected to the positive and negative terminals of the power supply, respectively. When energized, the wire contracts and tightens. When the wire is tightened, the spring seat is lifted, pressing the spring against the lower side of the horizontal surface of the energized post. The wires are located near the two relatively wide inner walls of the closed structure, where several clips are arranged to prevent the wires from deviating excessively from the inner walls. These clips are standard connectors in the construction industry, easily installed and removed without damaging the inner walls of the composite material. The SMA wires, arc ends, and clips are as follows: Figure 2 As shown.

[0100] Specifically, the multi-filament SMA is characterized by having 2-5 filaments, suitable for small and medium-sized wind turbine blades; and having more than 5 filaments, suitable for large wind turbine blades. The following illustrations in this specification use a two-filament design as an example.

[0101] The arc head is installed at the upper end of the closed structure. The arc head is made of insulating material and has two arc-shaped grooves. Two SMA wires pass through these grooves, wrapping around the arc head and descending downwards. Ventilation holes are formed in the thin wall of the cavity above the arc head, facing the upper edge (or leading edge). Small-diameter ventilation holes pass through the thin wall, running along its centerline downwards to exit at the blade root. The area of ​​these small-diameter holes is approximately 1 / 25 to 1 / 15 of the cross-sectional area of ​​the closed structure's cavity, ensuring that the outlet airflow velocity is sufficiently greater than the inlet airflow velocity, thus preventing interference between the hot and cold airflows at the blade root end face. If located at the upper edge, three holes can be formed (e.g., Figure 2 The aperture is relatively small; if it is opened at the leading edge, only one hole is opened (e.g. Figure 4 ( ), with a relatively large aperture.

[0102] The top of the energized stake is horizontal, with two side walls, one at the front and one at the back, close to the two opposing inner surfaces of the closed structure. Each side wall is secured to the inner surface of the closed structure with four bolts. The energized stake is located at the bottom of the closed structure, at the blade root. The bellows is an independent structure located inside the thin-walled closed structure, containing a fan. When the SMA filament temperature is too high, the fan activates, and airflow enters from inside the closed structure at the blade root, bypasses both ends of the energized stake from the side, ascends along the cavity, bypasses the arc head, exits through small-diameter holes in the side walls, flows downstream, and flows out through holes outside the closed structure at the blade root. The temperature of the SMA filament is read by an infrared thermometer, which is fixed near a clip at the midpoint of the closed structure's length. The bellows is installed near the blade root, at a position one-third of the blade's total length.

[0103] The spring is a lightweight, resilient spring. Its function is to use its extension force to separate the spring seat from the energized post when the metal wire is not energized. At the same time, when there is a large displacement fluctuation at the blade tip (not micro-high vibration), it ensures that the metal wire has a certain range of free movement. At this time, the SMA wire does not function. When the metal wire is energized, the spring is easily compressed, and the SMA wire begins to perform the function described in this manual.

[0104] Specifically, the design of the parameters of the lightweight, resilient spring—spring stiffness, the number, length, and diameter of the SMA wires, and the average wind force under normal operating conditions—follows the design plan of a "linear variable load actuator." The diameter of the SMA wires is selected between 0.3 and 1.1 mm.

[0105] In this embodiment, the detection method is as follows:

[0106] When the piezoelectric vibration pickup detects continuous micro-high vibration, the power supply to the energized pile is activated. Current flows through the SMA wire, causing the SMA to heat up and begin to contract. This contracts, tightening the arc head and simultaneously pulling the spring seat against the bottom of the energized pile. As the temperature further increases, the SMA wires continue to shorten, and the spring continues to compress (until it is fully compressed), thus gradually attenuating the vibration. When a certain temperature t0 is reached, the vibration disappears, and the bellows is activated. Figure 5 This refers to the bellows and its installation location. Air flows in from the bottom of the blade root and out through the channel at the top of the arc head. Temperature is detected by the aforementioned infrared thermometer and fed back to the controller. The controller controls the alternating on and off of the power supply to the SMA filament and fan (constant duty cycle), causing the temperature to fluctuate around t0, maintaining a state of vibration elimination until the wind speed sensor detects a significant change in wind conditions. In fact, the blade structure has already avoided the flutter area. At this point, the controller issues a command to disconnect the power supply, and the SMA filament gradually cools down and recovers its length. At this time, the micro-high vibration has completely disappeared.

[0107] If the maximum allowable temperature t of SMA wire is reached max If the micro-vibration does not completely disappear at that time, PID control is used to achieve the desired effect at time t. max Precise temperature control suppresses micro-vibrations (although the vibrations haven't completely disappeared, they've been reduced to a sufficiently safe level). Simultaneously, PID temperature control protects the SMA filament. As mentioned earlier, there are digital PID and analog PID control methods. Digital PID requires the controller (here, the PLC's CPU module) to output two switching signals, using PID calculations to output two pulse signals to control the power supply to the SMA filament and fan, achieving temperature control. Analog PID requires the PLC's CPU module to output an analog signal through the analog output module, controlling the frequency converter to further control the fan speed, achieving temperature control (the SMA power supply remains on). Similarly, until the wind speed sensor detects a significant change in wind conditions, the blade structure avoids the flutter area, and temperature control is no longer necessary. At this point, the controller issues a command to disconnect the power, the SMA filament gradually cools, and its length returns to normal.

[0108] The SMA wire here allows for a maximum temperature of t max , is the allowable temperature value at which the output performance degradation is minimized during repeated actuation tests of the selected SMA wire. After determining the SMA wire parameters according to the "linear variable load actuator" design plan, t max The value t occurs when the spring is fully compressed for a period of time, and the SMA temperature rises to a certain value, at which the actuation output performance degradation is minimal. max .

[0109] The above description is not intended to limit the functionality of the present invention. When the "quasi-rectangular" structure is approximately modified (for example, by thickening the two main beam caps of a conventional blade and combining them with two shear-resistant webs to approximately form a "quasi-rectangular" structure), the use of multi-wire SMA in the internal cavity of the thin-walled blade, stretching along the blade's span direction (the length direction of the closed structure), and suppressing micro- to high-frequency vibrations with temperature changes, are all considered to be similar to the design of this invention.

[0110] Example 7: Based on the above examples, this example further discloses the following:

[0111] Western my country is rich in wind energy resources and is a major area for the construction of large-scale wind power bases. However, the region has complex wind conditions, with high average annual wind speeds, strong turbulence, significant diurnal temperature variations, and frequent extreme gusts. Large wind turbines operating under these conditions bear complex alternating loads on their blades over long periods, making them highly susceptible to the "micro-amplitude high-frequency vibration" (frequency 5-25Hz, amplitude not exceeding 2mm) described in the manual. While this vibration is not easily detected directly, it is one of the main causes of latent cracks (such as skin delamination, web debonding, and micro-cracks in the main beam) within the composite blades. These latent defects seriously threaten the structural safety of the blades and are a significant potential cause of "large wind turbine failure." They are difficult to detect during routine inspections and are often only diagnosed during obvious damage (such as sudden breakage) or major disassembly and overhaul, resulting in high maintenance costs and significant downtime losses.

[0112] To overcome this challenge, this implementation case applies the "Blade Micro-Amplitude High-Frequency Vibration Suppression Device and System Based on Multi-Wire SMA" to a demonstration unit of a 200MW wind farm phase I project in a suburban city in western China. This project uses large wind turbine units with a single unit capacity of 2.0MW and a rotor diameter of 115 meters. This embodiment aims to verify the preventive effectiveness of this technology against latent blade faults in harsh wind farm environments. Through feedback from actual engineering data, it deepens the understanding of the initiation and propagation mechanisms of latent cracks and verifies the effectiveness of active measurement and control technology.

[0113] First, the target wind turbines and blades were selected. Three wind turbines located in areas of strong turbulence within the wind farm, and whose operational data monitoring had previously shown abnormal vibration trends, were chosen as the targets for modification. The blades are a glass fiber composite main beam + sandwich structure, with a length of 56 meters.

[0114] Then, system integration and installation are carried out. Device implantation: Inside each blade, along the critical stress zone of the main beam cap (approximately 1 / 3 of the blade length from the blade root, corresponding to the area of ​​maximum flapping moment), a "blade micro-amplitude high-frequency vibration suppression device based on multi-wire SMA" is implanted. Closed main structure: The original cavity structure of the blade's main beam cap is adaptively reinforced and interface-treated to serve as the device's load-bearing shell. Internal control mechanism: For large blades, eight 0.8mm diameter nickel-titanium shape memory alloy (SMA) wires are selected to enhance aerodynamic power. The SMA wires are guided by insulated arc heads, and their lower ends are connected to a spring-spring seat system inside an inverted U-shaped energizing post. The energizing post is firmly fixed to the inner wall of the main structure. Sensing mechanism: A piezoelectric vibration pickup is installed inside near the blade tip to accurately capture micro-amplitude high-frequency vibration signals; an infrared thermometer is installed on the inner wall near the device installation area to monitor the temperature of the SMA wire's working area in real time. External covering mechanism: The device's exterior is perfectly restored to the original honeycomb filler layer and skin shell of the blade, ensuring that the blade's aerodynamic shape is not affected.

[0115] Control system deployment: A dedicated PLC control system is added to the wind turbine nacelle control cabinet. This PLC integrates a high-speed analog input module (receiving vibration and temperature signals) and a digital / analog output module (controlling SMA power supply and fan operation). The PLC communicates with the wind turbine main control system to acquire wind speed sensor signals and unit operating status. A dedicated control algorithm program is developed to implement the vibration detection, SMA excitation, temperature closed-loop control (PID), and intelligent start-stop logic linked to wind conditions, as described in the manual.

[0116] The system operates as follows:

[0117] Monitoring: The PLC system continuously monitors the piezoelectric vibration pickup signal. When a vibration signal that lasts for more than 5 minutes and meets the "micro-high" characteristics is identified, it is determined to be a potentially risky operating condition.

[0118] Activation suppression: The PLC immediately triggers the SMA wire energization circuit. The SMA contracts upon heating, applying a controllable constraint / damping force opposite to the vibration to the blade body structure through the spring system. This changes the local stiffness or introduces active damping, thereby rapidly attenuating the micro-amplitude vibration at a specific frequency.

[0119] Temperature control and maintenance: Infrared thermometer provides temperature feedback. The system employs analog PID control: the PLC outputs an analog signal to control the speed of the variable frequency fan. By adjusting the airflow through the SMA wire area, the SMA wire temperature is precisely maintained near the optimal suppression temperature t0. This method avoids frequent switching of the SMA current, extending its lifespan.

[0120] Intelligent Exit: When the wind speed sensor indicates that the wind conditions have changed (such as the wind speed continuously exceeding or falling below the range that easily induces the specific micro-vibration), the blade system has left the "flutter risk zone", and the PLC automatically cuts off the SMA power supply and the fan, and the system enters the standby monitoring state.

[0121] From "post-incident repair" to "pre-incident prevention," the system tackles the challenge of latent faults: it directly targets the core mechanism leading to latent cracks—long-term, low-amplitude, high-frequency vibration—for active suppression. By eliminating vibration at its initial stage, the system fundamentally cuts off the initiation and development path of latent cracks (such as delamination and debonding), eliminating the fault in its nascent stage. This provides the most direct engineering intervention verification and effect feedback for the research on "the causes of latent faults."

[0122] Improve the safety and reliability of blade structure: effectively reduce the risk of sudden obvious fracture (such as blade tip fracture or main beam cracking) due to accumulated fatigue damage of blades under complex wind conditions (especially turbulent winds common in the west), and greatly improve the safety margin of the whole machine operation.

[0123] Extending blade service life: By suppressing micro-vibrations that cause internal material damage, the fatigue aging process of composite materials is slowed down. This is expected to significantly extend the design life of the blades, which means a fundamental improvement in asset utilization for large-scale wind power projects with huge investments.

[0124] Achieving intelligent sensing and adaptive control: Integrating piezoelectric sensing, infrared temperature measurement, and PLC intelligent algorithms, the blades possess intelligent characteristics of "sensing-analysis-action." The system can adapt to different wind conditions, activating only when needed, resulting in energy savings and high efficiency.

[0125] Convenience and non-invasiveness of maintenance: The main components of the device are integrated into the internal cavity of the blade, without changing the external aerodynamic shape of the blade and having no impact on the original performance of the unit. Later maintenance can be performed remotely via the control system; if necessary, only the internal modules need to be inspected, significantly reducing maintenance complexity.

[0126] The implementation of this technology creates considerable economic value, primarily reflected in direct cost savings, increased power generation revenue, and enhanced life-cycle value. The cost of a single large blade on-site repair or replacement is extremely high (reaching hundreds of thousands to millions of RMB), involving the rental of large hoisting equipment and prolonged downtime. This system, by preventing serious failures, is expected to avoid potentially huge maintenance costs per turbine annually. The demonstration project, with three turbines, is projected to avoid millions of RMB in potential maintenance losses over five years. It also prevents unplanned downtime and major overhaul shutdowns caused by blade damage. For example, avoiding a two-week blade overhaul for a single 2.0MW turbine can reduce power generation loss by approximately 67,000 kWh (estimated based on 2000 available hours). With large-scale application in wind farms, power generation revenue will increase significantly.

[0127] This system reduces investment in routine inspections and speculative maintenance. Traditional flaw detection requires downtime, expensive equipment, and highly skilled personnel. This system provides real-time status monitoring and proactive protection, shifting the maintenance strategy from routine inspections to predictive maintenance, reducing the intensity and frequency of daily inspections, and saving manpower and equipment costs. Blades are among the most expensive components of wind turbines. Extending blade life means reducing the amortization of the wind turbine's total lifecycle cost and extending the return on investment period. Preliminary estimates suggest that applying this system can effectively extend the fatigue life of key blade components, potentially increasing the overall project return on investment (IRR) by 1-2 percentage points. This successful implementation provides authoritative case studies and data support for promoting this technology in similar wind farms in western China and even nationwide. The resulting integrated "measurement-control-maintenance" solution can be transformed into high-value-added wind power aftermarket technical service products, creating new profit growth points.

[0128] This invention is not limited to the examples described above. Any changes, modifications, additions, or substitutions made by those skilled in the art within the scope of this invention should also fall within the protection scope of this invention.

Claims

1. A blade micro-amplitude high-frequency vibration suppression device based on multi-filament SMA, characterized in that, The blade includes a closed main structure and an outer covering mechanism. The closed main structure is connected to an internal control mechanism and a sensing mechanism. The outer covering mechanism includes a filler layer and a skin shell disposed outside the closed main structure. The internal control mechanism includes multiple shape memory alloy wires, an arc head, a bellows, a power supply stake, a spring, and a spring seat. The arc head is located inside the upper part of the closed main structure, and the power supply stake is installed inside the lower part of the closed main structure and is connected to the power supply stake via an electric wire. Multiple shape memory alloy wires independently pass around the arc head. The two ends of each shape memory alloy wire go downward through the horizontal surface of the power supply pile and connect to the spring seat set inside the power supply pile. The spring is sleeved on the outside of the shape memory alloy wire and fixed on the spring seat. The two ends of each shape memory alloy wire are respectively connected to the positive and negative terminals of the power supply pile. The shape memory alloy wire is constrained and positioned by several buckles on the inner wall of the closed main structure. The bellows is located inside the closed main structure above the electrified pile. Ventilation holes are opened on the inner wall of the upper cavity of the closed main structure facing the upper edge or leading edge of the blade. The ventilation holes pass through the thin wall of the closed main structure and extend downwards to the bottom of the closed main structure, closely following the center line of the thin wall. The sensing mechanism includes a piezoelectric pickup located at the top of the closed main structure and an infrared thermometer located on the inner wall of the middle of the closed main structure.

2. The blade micro-amplitude high-frequency vibration suppression device based on multi-filament SMA according to claim 1, characterized in that, The closed main structure is a thin-walled shell structure made of composite material. The cross-sectional shape of the closed main structure is frustum-shaped. The width of the upper part of the closed main structure near the leading edge of the airfoil is greater than the width of the lower part of the closed main structure. Each surface of the outer surface of the closed main structure is a plane, used to support the honeycomb-shaped filler layer, and the outermost edge of the filler layer is a skin shell structure. Each surface of the inner surface of the closed main structure is also a plane, used for installing the arc head, bellows, power supply pile, and clips; The closed main structure extends through the leaf root, and the distance from the top of the closed main structure to the leaf tip is approximately 1 / 7 to 1 / 6 of the total length of the leaf.

3. The blade micro-amplitude high-frequency vibration suppression device based on multi-filament SMA according to claim 1, characterized in that, The shape memory alloy wires are arranged at independent intervals; The electrified pile is in the shape of an inverted U-shaped plate, and its two side walls are fixedly connected to the inner surface of the closed main structure by bolts.

4. The blade micro-amplitude high-frequency vibration suppression device based on multi-filament SMA according to claim 1, characterized in that, The bellows is an independent structure, and a fan is installed inside the bellows. The fan is a fixed-frequency fan or a variable-frequency fan. The bellows is installed near the blade root, at a position one-third of the total blade length. An infrared thermometer is connected to the fan via a circuit.

5. The blade micro-amplitude high-frequency vibration suppression device based on multi-filament SMA according to claim 1, characterized in that, The arc head is composed of a lower positioning block and an upper arc-shaped block. Both the lower positioning block and the upper arc-shaped block are made of insulating material. Several parallel alloy wire limiting grooves are formed on the outer surface of the arc head.

6. The blade micro-amplitude high-frequency vibration suppression device based on multi-filament SMA according to claim 1, characterized in that, When the number of shape memory alloy wires is 2-5, it is used in the blades of small and medium-sized wind turbines; when the number of shape memory alloy wires is greater than 5, it is used in the blades of large wind turbines. The spring is a circular spring made of lightweight and tough material. One end of the spring is fixed to a flat cylindrical spring seat, and the other end of the spring is connected to the lower end face of the energized stake. A shape memory alloy wire passes through the spring, and the diameter of the shape memory alloy wire is 0.31mm-1.1mm.

7. A blade micro-amplitude high-frequency vibration suppression system based on multi-filament SMA, characterized in that, The blade micro-amplitude high-frequency vibration suppression device based on multi-filament SMA as described in any one of claims 1 to 6 is used in at least one blade of a wind turbine. The blade micro-amplitude high-frequency vibration suppression system also includes a PLC control system installed inside the wind turbine and a wind speed sensor installed on the blade or the outer surface of the wind turbine. The PLC control system is connected to the main power supply of the wind turbine through a line; the PLC control system is also connected to the internal control mechanism, the sensing mechanism, and the wind speed sensor through a line.

8. A method for suppressing micro-amplitude high-frequency vibration of blades, characterized in that, The blade micro-amplitude high-frequency vibration suppression system based on multi-filament SMA as described in claim 7 includes the following steps: S1. After the system starts, the PLC control system is powered on, and the sensors in the corresponding internal control mechanism and sensing mechanism are powered on; the piezoelectric vibration pickup enters the vibration detection mode, the infrared thermometer enters the temperature detection mode, and the wind speed sensor enters the external wind speed detection mode. S2: When the piezoelectric vibration pickup detects a signal with a vibration amplitude of no more than 2 mm and a vibration frequency of 5-25 Hz, if the signal lasts for more than 5 minutes, it is considered that the blade system has experienced continuous micro-high vibration under normal operating conditions, and then S3 is executed; otherwise, the vibration detection mode is maintained. S3, when the power supply is connected to the energized pile, the current passes through the shape memory alloy wire SMA. The SMA temperature rises and begins to contract, which on the one hand tightens the arc head, and on the other hand, the two wires of SMA pull the spring seat to move towards the bottom of the energized pile. S4, as the temperature further increases, the SMA wire continues to shorten, and the spring and spring seat continue to compress until the spring seat is tightly pressed. If the vibration continues to decay, it will disappear when a certain temperature t0 is reached, then S5 is executed; if the maximum allowable temperature t of the SMA is reached... max If the micro-vibration has not completely disappeared, then execute S9; S5, turn on the bellows. The airflow enters from the inside of the closed main structure at the blade root. The airflow goes around the two ends of the electrified pile from the side and goes up along the cavity of the closed main structure. After going around the arc head, it goes out through the small diameter hole on the side wall of the closed main structure and flows down and out through the hole on the outside of the closed main structure. S6, the infrared thermometer detects and reads the temperature inside the closed main structure in real time, and feeds it back to the PLC controller in the PLC control system. The PLC controller controls the power supply of SMA and fan to alternately turn on and off, so that the temperature fluctuates around t0 and maintains a state of vibration elimination. S6, until the wind speed sensor detects a significant change in wind conditions, at which point the blade structure has avoided the flutter area. At this point, the PLC controller issues a command to disconnect the power supply, the SMA gradually cools down, and the length elongates and recovers. At this point, the micro-high vibration has completely disappeared. S8 is controlled by a PID control module to achieve the desired result at t max The precise temperature control helps to suppress micro-vibrations; although the vibration has not completely disappeared, it has been reduced to a sufficiently safe level, and the PID control module can protect the SMA wire. Similarly, S9, until the wind speed sensor detects a significant change in wind conditions, the blade structure avoids the flutter area and there is no need to continue the constant temperature control of the PID control module; at this time, the PLC controller issues a command to disconnect the power supply, the SMA filament gradually cools down, and the length elongation is restored.

9. A method for suppressing micro-amplitude high-frequency vibration of a blade according to claim 8, characterized in that, The control method within the PID control module can be either digital PID or analog PID. The digital PID method requires the CPU module in the PLC controller to output two switching signals, and then use PID calculation to output two pulse signals to control the power supply of the SMA wire and the fan to achieve the goal of constant temperature control. The analog PID method requires the CPU module in the PLC controller to output an analog signal through the analog output module, which controls the frequency converter to further control the fan speed to achieve the goal of constant temperature control. At this time, the SMA power supply is always on.

10. A method for suppressing micro-amplitude high-frequency vibration of a blade according to claim 8, characterized in that, The maximum allowable temperature t in S4 SMA max It is the allowable temperature value at which the output performance of the selected SMA wire is minimized during repeated operation tests; highest temperature t max The method for determining t is as follows: when the parameters of spring stiffness, number, length and diameter of SMA, and average wind force under normal working conditions are designed in accordance with the design plan of linear variable load actuator, t max The value t occurs when the spring is fully compressed for a period of time, and the SMA temperature rises to a certain value, at which the actuation output performance degradation is minimal. max .

Images