Vibration excitation device for wind power blade fatigue test

Abstract

The invention relates to a vibration excitation device for a wind power blade fatigue test, the vibration excitation device is arranged on a loading assembly, the device comprises a blade assembly and a vibration excitation assembly, the blade assembly comprises a blade, a clamp and a balancing weight, the root of the blade is installed on a loading support of the loading assembly, the clamp is installed on the blade and is connected with the vibration excitation assembly, and the balancing weight is connected with the blade assembly. The balancing weight is arranged on the clamp; the excitation assembly comprises a motor, a winding drum and a cable, the motor is in driving connection with the winding drum and used for driving the winding drum to rotate, one end of the cable is fixed and wound on the winding drum, and the other end of the cable is connected with the clamp; the cable is in a tensioned state, and the included angle between the cable and the chord line plane of the blade is smaller than 90 degrees. Compared with the prior art, the double-shaft vibration of the blade is excited by pulling the blade obliquely through the cable, and the device has the advantages of simple structure, low test cost, avoidance of the influence of gravity on the result and the like.

Description

Technical Field

[0001] The invention relates to the technical field of wind turbine blade fatigue testing, and in particular to a vibration excitation device for wind turbine blade fatigue testing. Background Art

[0002] Since wind turbines need to serve for a long time under harsh natural conditions, blades as key components must be fatigue tested to verify their durability. As blades grow larger, resonance testing schemes are generally used to reduce energy consumption. Biaxial testing can simulate combined loads and shorten test time. At present, the optional excitation devices for biaxial test vibration platforms include pendulum type, linear motor type, hydraulic cylinder type, etc.

[0003] The invention with announcement number CN109185244A discloses a hydraulic system matching with a wind turbine blade biaxial fatigue test bench. The electric motor drives a constant pressure variable pump to pump the hydraulic oil in the oil tank to the integrated block, and then the oil is diverted by a large oil distributor and sent to the double piston rod hydraulic cylinder assembly through a small oil distributor under the regulation of a proportional servo valve, driving the mass block to reciprocate, forcing the wind turbine blade to achieve biaxial fatigue loading in the swing and swing directions. The liquid level, temperature and pressure are monitored with the help of a liquid level gauge, an electric contact thermometer and a pressure gauge, and the oil is filtered with the help of a pressure line filter and a return oil filter. The line pressure is adjusted and maintained with the help of an accumulator, a relief valve and a flow control valve. The double piston rod hydraulic cylinder assembly is firmly fixed on the wind turbine blade with the help of a frame and an adjusting bolt, which has the advantages of easy profiling, adjustable position and no damage to the blade. However, this hydraulic system is complex to install and maintain, difficult to control, and the loading process needs to overcome the deadweight of the mass block.

[0004] Therefore, the above existing fatigue excitation system has the following problems:

[0005] 1. The use of an inertial exciter will add gravity to the blades, causing a large shear load. 2. The excitation system for completing the biaxial test is relatively complex, with high testing costs, and does not balance the requirements and control difficulties of the resonance test. 3. The fatigue test process does not fully consider the impact of gravity loads. Summary of the invention

[0006] The purpose of the present invention is to provide an excitation device for wind turbine blade fatigue testing in order to overcome the defects of the prior art that an inertial oscillator is installed on the blade, which adds gravity to the blade and causes a large shear load, and the inertial exciter has a complex structure.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] A vibration excitation device for wind turbine blade fatigue test, arranged on a loading assembly, comprising a blade assembly and a vibration excitation assembly, wherein the blade assembly comprises a blade, a fixture and a counterweight, wherein the root of the blade is mounted on a loading support of the loading assembly, the fixture is mounted on the blade and connected to the vibration excitation assembly, and the counterweight is arranged on the fixture;

[0009] The excitation assembly includes a motor, a drum and a cable. The motor drives the connected drum to drive the drum to rotate. One end of the cable is fixed and wound on the drum, and the other end is connected to a clamp. The cable is in a tensioned state, and the angle between the cable and the chord plane of the blade is less than 90 degrees.

[0010] Preferably, the device includes a first excitation component and a second excitation component, the chord plane of the blade is horizontally arranged, the clamp is provided with a mounting hole, the cables of the first excitation component and the second excitation component are respectively connected to the mounting holes, and the angle between the axis of the cable of the first excitation component and the axis of the cable of the second excitation component is greater than 0 degree.

[0011] Preferably, the axis of the cable of the first excitation assembly and the axis of the cable of the second excitation assembly are both located in a vertical section of the blade passing through the mounting hole, and the angle between the axis of the cable of the first excitation assembly and the chord plane of the blade is equal to the angle between the axis of the cable of the second excitation assembly and the chord plane of the blade.

[0012] Preferably, the blade has a first resonant frequency in a vertical flapping direction and a second resonant frequency in a horizontal swinging direction, the fundamental frequency of the tension on the cable of the first excitation assembly is the same as that of the first excitation assembly, and the fundamental frequency of the tension on the cable of the second excitation assembly is the same as the second resonant frequency.

[0013] Preferably, the device has a vibration excitation component, the chord plane of the blade is arranged horizontally, the fixture is provided with a mounting hole, and the cable of the vibration excitation component is connected to the mounting hole.

[0014] Preferably, the blade has a first resonant frequency in the vertical flapping direction and a second resonant frequency in the horizontal swinging direction, and the tension on the cable of the excitation assembly has a first fundamental frequency and a second fundamental frequency, the first fundamental frequency is the same as the first resonant frequency, and the second fundamental frequency is the same as the second resonant frequency.

[0015] Preferably, a phase difference is set between the first fundamental frequency and the second fundamental frequency.

[0016] Preferably, the device has a vibration component, the angle between the chord plane of the blade and the horizontal plane is greater than 0 degrees and less than 90 degrees, the fixture is provided with a mounting hole, the cable of the vibration component is connected to the mounting hole, and the cable is arranged vertically.

[0017] Preferably, the device further comprises a support and a torsion spring, wherein the support is arranged on the ground, the reel is rotatably fixed on the support and placed horizontally, one end of the torsion spring is fixed on the ground, and the other end is connected to an end of the reel away from the motor;

[0018] When the blade is at the lowest vibration point, the torsion spring is in the original length state;

[0019] When the blade is at the highest vibration point, the torsion spring is in a compressed state.

[0020] Preferably, the clamp is a detachable structure, the clamp is provided with bolts, the clamp is detachably fixed to the blade by the bolts, and a plurality of clamps are provided on the blade.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] (1) In this scheme, the root of the blade is installed on the loading support, and the fixture is installed on the blade. The fixture is used to set the counterweight block and connect the cable of the excitation component to complete the assembly of the excitation device; then the motor drives the drum to reciprocate to realize the periodic retraction and release of the cable, driving the fixture and the blade to move, thereby applying excitation force to the blade and performing fatigue testing on the blade.

[0023] The blade is fixed on the loading support, and the motor is used to drive the drum to rotate back and forth, so that the cable is periodically retracted and released. The exciting force is applied to the blade through the fixture connected to the cable and fixed on the blade, driving the blade to swing vertically and swing horizontally. Compared with the inertial exciter installed on the blade, the excitation device is easier to install, and the weight of the excitation device will not affect the blade test, and will not change the resonance frequency of the blade system, so the test results are more accurate.

[0024] (2) In this scheme, the fixture connects two excitation components through cables. The angle between the axis of the cables on both sides and the vertical direction is adjustable. There is an adjustable phase difference between the fundamental frequency components of the tension in the cables on both sides, which can control the combined load during the biaxial test of the blade. The constant components of the tension in the cables on both sides cancel each other out in the swing direction, thereby improving the vibration trajectory offset phenomenon in the biaxial test.

[0025] (3) In this scheme, an excitation component can be set to set an angle between the cable axis and the vertical direction. There are two fundamental frequency components of the tension in the cable, which act on the swing direction and the swing direction of the blade through the load angle. Adjusting the cable deflection angle and the phase difference of the fundamental frequency component can control the vibration trajectory and test energy consumption, and complete the biaxial test. Moreover, the actual form of the tension in the cable can be smoothed and filtered based on the target form, thereby improving the operability in the actual test, making full use of equipment conditions, and reducing test costs.

[0026] (4) In this scheme, an excitation component can also be set up so that the axis of the cable is set vertically and the chord plane at the root of the blade has an angle with the horizontal direction. The unidirectional load applied to the blade by the downward pull of the cable and the gravity of the counterweight block will affect the fatigue damage during the test process, especially when it only acts in the swing direction; the unidirectional load after the cable is set vertically can be decomposed into the swing direction and the swing direction to weaken this effect, and changing the amplitude of the tension in the cable can further compensate, correcting the influence of the unidirectional load superposition effect and improving the test accuracy and reliability.

[0027] (5) This scheme installs a torsion spring on the output shaft at the end of the drum away from the motor. Under the premise that the cable is always tensioned, the torsion spring is in its original length when the blade is at the lowest point of vibration; when the blade vibrates from the lowest point to the highest point, the motor performs positive work on the torsion spring through the drum, and the torsion spring rotates through a certain angle to store elastic potential energy; when the blade vibrates from the highest point to the lowest point, the motor and the torsion spring simultaneously perform positive work on the drum, and the torsion spring releases elastic potential energy; the energy output by the motor during the blade rebound process is fully utilized to reduce the peak load of the motor when it reaches full load, and to fully utilize the motor power capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of the structure of the vibration excitation device provided by the present invention;

[0029] Figure 2 A schematic diagram of the structure of two excitation components provided in Example 1 of the present invention;

[0030] Figure 3 A schematic diagram of the structure of a vibration excitation assembly provided in Example 2 of the present invention with blades arranged horizontally;

[0031] Figure 4 A schematic diagram of a structure of a vibration excitation assembly provided in Embodiment 3 of the present invention with a vertically arranged cable;

[0032] Figure 5 A schematic diagram of a structure in which a torsion spring is provided at the output end of the reel provided in Embodiment 4 of the present invention;

[0033] In the figure: 1. blade, 2. bolt, 3. clamp, 4. counterweight, 5. loading support, 6. chord plane, 7. first excitation component, 8. second excitation component, 11. cable, 12. support, 13. drum, 14. motor, 21. torsion spring. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0035] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0037] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships in which the inventive product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0038] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0039] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0040] Example 1

[0041] like Figure 1 and Figure 2As shown, this embodiment provides a vibration excitation device for wind turbine blade fatigue test, which is arranged on a loading assembly. The device includes a blade assembly and a vibration excitation assembly. The blade assembly includes a blade 1, a fixture 3 and a counterweight 4. The root of the blade 1 is installed on a loading support 5 of the loading assembly. The fixture 3 is installed on the blade 1 and connected to the vibration excitation assembly. The counterweight 4 is arranged on the fixture 3.

[0042] The excitation assembly includes a motor 14, a drum 13 and a cable 11. The motor 14 drives the drum 13 to drive the drum 13 to rotate. One end of the cable 11 is fixed and wound on the drum 13, and the other end is connected to the clamp 3. The cable 11 is in a tensioned state, and the angle between the cable 11 and the chord plane 6 of the blade 1 is less than 90 degrees.

[0043] Working principle: The root of the blade 1 is installed on the loading support 5, and the clamp 3 is installed on the blade 1. The clamp 3 is used to set the counterweight block 4 and connect the cable 11 of the excitation assembly to complete the assembly of the excitation device; then the motor 14 drives the drum 13 to rotate reciprocatingly to realize the periodic retraction and release action of the cable 11, driving the clamp 3 and the blade 1 to move, thereby applying an exciting force to the blade 1 and performing a fatigue test on the blade 1.

[0044] By fixing the blade 1 on the loading support 5, the motor 14 is used to drive the drum 13 to rotate back and forth, so that the cable 11 is periodically retracted and released, and the exciting force is applied to the blade by the clamp 3 connected to the cable 11 and fixed on the blade 1, so as to drive the blade 1 to swing in the vertical direction and swing in the horizontal direction. Compared with the inertial exciter installed on the blade, the excitation device is easier to install, and the weight of the excitation device will not affect the blade test, and will not change the resonance frequency of the blade system, so the test results are more accurate.

[0045] Among them, the excitation component includes a first excitation component 7 and a second excitation component 8, the chord plane 6 of the blade 1 is horizontally arranged, a mounting hole is provided on the clamp 3, the cables 11 of the first excitation component 7 and the second excitation component 8 are respectively connected to the mounting holes, and the angle between the axis of the cable 11 of the first excitation component 7 and the axis of the cable 11 of the second excitation component 8 is greater than 0 degree.

[0046] The axis of the cable 11 of the first excitation component 7 and the axis of the cable 11 of the second excitation component 8 are both located in the vertical section of the blade passing through the mounting hole, and the angle between the axis of the cable 11 of the first excitation component 7 and the chord plane 6 of the blade 1 is equal to the angle between the axis of the cable 11 of the second excitation component 8 and the chord plane 6 of the blade 1.

[0047] The blade 1 has a first resonance frequency in the vertical swing direction and a second resonance frequency in the horizontal swing direction, the fundamental frequency of the tension on the cable 11 of the first excitation component 7 is the same as the first excitation component 7, and the fundamental frequency of the tension on the cable 11 of the second excitation component 8 is the same as the second resonance frequency. An adjustable phase difference is provided between the fundamental frequency of the tension on the cable 11 of the first excitation component 7 and the fundamental frequency of the tension on the cable 11 of the second excitation component 8.

[0048] Furthermore, the clamp 3 is a detachable structure, a bolt 2 is provided on the clamp 3 , the clamp 3 is detachably fixed to the blade 1 by the bolt 2 , and a plurality of clamps 3 are provided on the blade 1 .

[0049] Specifically, in this embodiment, the root of the blade 1 is fixedly mounted on the loading support, the root chord plane 6 is aligned with the horizontal direction, and one end of the cable 11 is bound to the mounting hole of the fixture 3. Two sets of exciting components are respectively arranged on the ground on both sides of the vertical plane where the axis of the blade 1 is located, and the motor 14 drives the drum 13 to reciprocate to realize the retraction and release action of the cable 11, thereby applying an exciting force to the blade 1.

[0050] The fundamental frequency of the tension in the cable 11 of the first excitation component 7 is the same as the resonance frequency of the system in the swing direction, and the fundamental frequency of the tension in the cable 11 of the second excitation component 8 is the same as the resonance frequency of the system in the swing direction. The angle between the axis of the ropes 11 on both sides and the vertical direction is variable, and there is an adjustable phase difference between the fundamental frequency components of the tension in the cables 11 on both sides, so the combined load of the biaxial test process can be controlled. The constant components of the tension in the cables 11 on both sides cancel each other in the swing direction, thereby improving the vibration trajectory deviation phenomenon in the biaxial test.

[0051] Specifically, two symmetrically arranged excitation components are used to excite the blades to swing horizontally and swing vertically. When the excitation forces of the first excitation component 7 and the second excitation component 8 are different, the blades will swing horizontally and swing vertically. The excitation forces of the first excitation component 7 and the second excitation component 8 are adjusted to adjust the excitation force of the blades. When the excitation forces of the first excitation component 7 and the second excitation component 8 are the same, and the excitation timing (phase) of the two is completely synchronized, the blades can move purely in the swinging or swinging direction. If the phases of 7 and 8 are different, even if they are equal in size, they will pull the blades to perform biaxial motion in space. By adjusting the excitation force or excitation timing of the two excitation components, various forms of movement of the blades can be stimulated.

[0052] The system resonant frequency can be obtained by real-time spectrum analysis of the strain signal of blade 1, thereby adjusting the fundamental frequency of the tension in cable 11. The system resonant frequency is not only related to the inherent properties of blade 1, but also affected by fixture 3 and counterweight 4. According to the actual loading force in the swing direction and the swing direction, a frequency domain weighted index is established to adjust the tension form in the cables 11 on both sides to reduce the test energy consumption.

[0053] The inherent amplitude-frequency characteristic of the mechanical system is that the vibration in a certain frequency band is more prominent, so the frequency components of the actual loading force outside the resonance zone can be filtered out in the vibration, so the form of the tension in the ropes 11 on both sides does not need to be too complicated, thereby reducing the control cost.

[0054] Example 2

[0055] like Figure 3 As shown, this embodiment is basically the same as embodiment 1, except that the device has a vibration assembly, the chord plane 6 of the blade 1 is horizontally arranged, a mounting hole is provided on the clamp 3, and the cable 11 of the vibration assembly is connected to the mounting hole.

[0056] The blade 1 has a first resonance frequency in the vertical swinging direction and a second resonance frequency in the horizontal swinging direction, and the tension on the cable 11 of the excitation assembly has a first fundamental frequency and a second fundamental frequency, the first fundamental frequency is the same as the first resonance frequency, and the second fundamental frequency is the same as the second resonance frequency. A phase difference is set between the first fundamental frequency and the second fundamental frequency.

[0057] Specifically, only one set of exciting components is retained, and the axis of the cable 11 is at an angle to the vertical direction. There are two fundamental frequency components of the tension in the cable 11, which act on the swing direction and the swing direction of the blade 1 through the load angle. Adjustment of the phase difference of the deflection angle and the fundamental frequency component of the cable 11 can control the vibration trajectory and the test energy consumption, and complete the biaxial test. The actual form of the tension in the cable 11 can be smoothed and filtered on the basis of the target form, thereby improving the operability in the actual test. This embodiment can make full use of equipment conditions and reduce test costs.

[0058] Example 3

[0059] like Figure 4 As shown, this embodiment is basically the same as Embodiment 2, except that the device has an excitation component, the angle between the chord plane 6 of the blade 1 and the horizontal plane is greater than 0 degrees and less than 90 degrees, a mounting hole is provided on the clamp 3, and the cable 11 of the excitation component is connected to the mounting hole, and the cable 11 is vertically arranged.

[0060] Specifically, the exciting component is arranged directly below the blade 1, the axis of the cable 11 is located in the vertical plane, and the chord line of the root section of the blade 1 is at an angle with the horizontal direction. By rotating the installation angle of the blade from the pure swinging (horizontal) direction to a certain angle, such as 45 degrees, even a single vertical exciting force can excite the biaxial motion of the entire blade in the swinging and shimmying directions. The unidirectional load applied to the blade 1 by the downward pull of the cable 11 and the gravity will affect the fatigue damage during the test, especially when it only acts in the swinging direction. After the unidirectional load is decomposed into the swinging direction and the shimmying direction, this effect can be weakened, and changing the amplitude of the tension in the cable 11 can further compensate. This embodiment corrects the influence of the superposition effect of the unidirectional load and improves the test accuracy.) Changing the blade installation form to adjust the direction of gravity relative to the blade coordinate system and modifying the loading force amplitude can compensate for the influence of the unidirectional load on structural damage and improve the reliability of the test results.

[0061] Example 4

[0062] like Figure 5 As shown, this embodiment is basically the same as the embodiment 1, except that the device further comprises a support 12 and a torsion spring 21, the support 12 is set on the ground, the reel 13 can be rotatably fixed on the support 12 and is placed horizontally, one end of the torsion spring 21 is fixed on the ground, and the other end is connected to the end of the reel 13 away from the motor 14;

[0063] When the blade 1 is at the lowest vibration point, the torsion spring 21 is in the original length state;

[0064] When the blade 1 is at the highest point of vibration, the torsion spring 21 is in a compressed state.

[0065] Specifically, a torsion spring 21 is installed on the output shaft at the other end of the drum 13. Under the premise that the cable 11 is always tensioned, the torsion spring 21 is in its original length when the blade 1 is at the lowest point of vibration. When the blade 1 vibrates from the lowest point to the highest point, the motor 14 performs positive work on the torsion spring 21 through the drum 13, and the torsion spring 21 rotates a certain angle to store elastic potential energy; when the blade 1 vibrates from the highest point to the lowest point, the motor 14 and the torsion spring 21 simultaneously perform positive work on the drum 13, and the torsion spring 21 releases elastic potential energy.

[0066] This embodiment stores energy in the half cycle when the motor 14 does not work on the blade 1, and then releases the energy in the half cycle when the motor 14 does work on the blade 1, thereby reducing the demand for the output torque of the motor 1 in this stage and fully utilizing the power of the motor 1. The torsion spring is used as an energy storage element to fully utilize the energy output by the motor during the blade rebound process, reduce the peak load of the motor when it reaches full load, and fully utilize the power capacity of the motor.

[0067] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A vibration excitation device for wind turbine blade fatigue testing, arranged on a loading assembly, characterized in that: The device comprises a blade assembly and an excitation assembly, wherein the blade assembly comprises a blade (1), a fixture (3) and a counterweight (4), wherein the root of the blade (1) is mounted on a loading support (5) of the loading assembly, the fixture (3) is mounted on the blade (1) and connected to the excitation assembly, and the counterweight (4) is arranged on the fixture (3); The excitation component comprises a motor (14), a drum (13) and a cable (11); the motor (14) drives the connected drum (13) to drive the drum (13) to rotate; one end of the cable (11) is fixed and wound on the drum (13), and the other end is connected to the clamp (3); the cable (11) is in a tensioned state, and the angle between the cable (11) and the chord plane (6) of the blade (1) is less than 90 degrees.

2. The vibration excitation device for wind turbine blade fatigue testing according to claim 1, characterized in that: The device has two excitation components, including a first excitation component (7) and a second excitation component (8); the chord plane (6) of the blade (1) is arranged horizontally; a mounting hole is arranged on the fixture (3); cables of the first excitation component (7) and the second excitation component (8) are respectively connected to the mounting holes; and an angle between an axis of the cable of the first excitation component (7) and an axis of the cable of the second excitation component (8) is greater than 0 degrees.

3. The vibration excitation device for wind turbine blade fatigue testing according to claim 2, characterized in that: The axis of the cable of the first excitation component (7) and the axis of the cable of the second excitation component (8) are both located in the vertical section of the blade passing through the mounting hole, and the angle between the axis of the cable of the first excitation component (7) and the chord plane (6) of the blade (1) is equal to the angle between the axis of the cable of the second excitation component (8) and the chord plane (6) of the blade (1).

4. The vibration excitation device for wind turbine blade fatigue testing according to claim 2, characterized in that: The blade (1) has a first resonance frequency in a vertical flapping direction and a second resonance frequency in a horizontal swinging direction; the fundamental frequency of the tension on the cable of the first vibration component (7) is the same as that of the first vibration component (7); and the fundamental frequency of the tension on the cable of the second vibration component (8) is the same as the second resonance frequency.

5. The vibration excitation device for wind turbine blade fatigue testing according to claim 1, characterized in that: The device comprises a vibration excitation component, the chord plane (6) of the blade (1) is arranged horizontally, a mounting hole is arranged on the clamp (3), and a cable (11) of the vibration excitation component is connected to the mounting hole.

6. The vibration excitation device for wind turbine blade fatigue testing according to claim 5, characterized in that: The blade (1) has a first resonance frequency in a vertical swinging direction and a second resonance frequency in a horizontal swinging direction, and the tension on the cable (11) of the excitation component has a first fundamental frequency and a second fundamental frequency, the first fundamental frequency is the same as the first resonance frequency, and the second fundamental frequency is the same as the second resonance frequency.

7. The vibration excitation device for wind turbine blade fatigue testing according to claim 6, characterized in that: There is a phase difference between the first fundamental frequency and the second fundamental frequency.

8. The vibration excitation device for wind turbine blade fatigue testing according to claim 1, characterized in that: The device comprises a vibration excitation component, wherein the angle between the chord plane (6) of the blade (1) and the horizontal plane is greater than 0 degrees and less than 90 degrees, the clamp (3) is provided with a mounting hole, the cable (11) of the vibration excitation component is connected to the mounting hole, and the cable (11) is arranged vertically.

9. The vibration excitation device for wind turbine blade fatigue testing according to claim 1, characterized in that: The device also includes a support (12) and a torsion spring (21), wherein the support (12) is arranged on the ground, the reel (13) is rotatably fixed on the support (12) and is placed horizontally, one end of the torsion spring (21) is fixed on the ground, and the other end is connected to an end of the reel (13) away from the motor (14); When the blade (1) is at the lowest vibration point, the torsion spring (21) is in an original length state; When the blade (1) is at the highest vibration point, the torsion spring (21) is in a compressed state.

10. A vibration excitation device for wind turbine blade fatigue testing according to claim 1, characterized in that: The clamp (3) is a detachable structure. A bolt (2) is provided on the clamp (3). The clamp (3) is detachably fixed to the blade (1) via the bolt (2). A plurality of clamps (3) are provided on the blade (1).

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