Method for reducing vibrations in a rotor blade of a wind turbine

Abstract

A method (200) for reducing vibrations in one or more rotor blades (120) of a wind turbine (160) when the wind turbine is in a stopped condition is provided. The method includes measuring (201) one or more deformation parameters indicative of a deformation of the one or more blades (120), determining (202), at a dedicated controller (190) for an auxiliary drive system (20, 107), vibrations of one or more of the blades (120) based on the deformation parameters, wherein the dedicated controller (190) for the auxiliary drive system is separate from a wind turbine controller (180), and generating (203), at the dedicated controller (190), an output signal to operate the auxiliary drive system to reduce the vibrations. A wind turbine (160) including the dedicated controller (190) configured to determine vibrations and generate an output signal to reduce the vibrations when the wind turbine is in a stopped condition is also disclosed.

Description

Technical Field

[0001] This disclosure relates to methods for reducing vibrations in rotor blades of wind turbines, and wind turbines configured to implement such methods for reducing vibrations. Background Technology

[0002] Modern wind turbines are commonly used to supply electricity to the power grid. This type of wind turbine generally consists of a tower and a rotor mounted on the tower. The rotor, typically comprising a hub and multiple blades, rotates under the influence of wind on the blades. This rotation generates torque, which is typically transmitted to a generator either directly via the rotor shaft (“direct drive”) or through a gearbox. In this way, the generator produces electricity that can be supplied to the power grid.

[0003] There is a trend toward making wind turbine blades longer to capture more wind and convert wind energy into electricity. This makes the blades more flexible and more susceptible to aeroelastic instabilities, such as blade vibration. Vibrating blades can also excite rotor modes, posing a significant risk of potential damage throughout the wind turbine.

[0004] When a wind turbine is in operation, the turbine controller can directly or indirectly operate any auxiliary drive systems (such as pitch or yaw systems) to reduce the load on the blades. This counteracts blade vibrations. However, when the wind turbine is stationary (idling or locked), aeroelastic instability can also be a serious problem. In particular, such oscillations include edgewise oscillations.

[0005] At least two oscillations or vibrations along the edges can occur during the stationary state. The first oscillation or vibration is a so-called vortex-induced vibration when the angle of attack is approximately 90 degrees, and vortex shedding can occur at frequencies close to the blade's natural frequency. The second oscillation or vibration is a stall-induced vibration when the angle of attack is close to the stall angle (e.g., 15–20 degrees), and the interaction of the flow can cause blade vibration. The angle of attack can be understood as the geometric angle between the direction of wind flow and the chord of the rotor blades.

[0006] Vibrations caused by vortices and stall are phenomena that are difficult to simulate with existing technological tools, and therefore are usually ignored during the design phase. These can lead to blade root failures or accelerated fatigue damage due to blade laminations, blade bolts, etc. When all blades vibrate in phase, there is a potential risk of significant failures. Worse still, this can be caused by rotor blades vibrating resonantly. Resonance, even if it lasts only a short time and does not cause significant failures, can generate loads that can affect the fatigue life of structural components. Because information about the load and time range is unavailable, the effects of these loads are often impossible to calculate.

[0007] When the rotor is locked (e.g., due to installation, commissioning, or maintenance tasks), it cannot rotate to mitigate vibration. Especially when the wind turbine is not yet operational (e.g., the turbine is installed but not yet commissioned, or inactive if communication loss or any other failure prevents communication with the controller), the turbine yaw and blade pitch angles are fixed, and the rotor angle or azimuth is also fixed. If the controller (such as software, firmware, etc.) is also not operational, none of these three movements—yaw, pitch, and rotor—can be changed. Because none of those movements can be used to alleviate load and / or reduce vibration, the risk of excessive vibration or even resonance can be higher.

[0008] Wind turbines are typically not operated after installation and before commissioning is completed. They may also be stopped during maintenance (which requires rotor locking or at least shutdown).

[0009] The risk of major failures of inactive wind turbines can be reduced by properly aligning the nacelle with the prevailing wind direction and speed. However, because the wind turbines are not yet commissioned, manual intervention is required to trigger the yaw mechanism to rotate the nacelle relative to the tower if the wind direction or speed changes.

[0010] Furthermore, wind turbines can be stationary for extended periods, with the rotor locked and no controllers triggered within the turbine. Due to installation constraints in large wind turbine farms with several turbines to be installed, some turbines may be installed but not commissioned until weeks or months later. Offshore projects are a clear example of this. Commissioning personnel may be prevented from traveling to the turbines for commissioning due to weather conditions (such as wind speed or high waves). In these situations where the rotor is stationary for extended periods without active control, blade instability can pose a significant risk, potentially causing severe damage to the blades or their bolted connections. It can also induce rotor vibration modes, leading to major failures. This situation is particularly important for large wind turbine blades, which are typically found in offshore applications.

[0011] Current solutions to the aforementioned problems include using aerodynamic devices attached to the blades to reduce vortex and stall. However, this solution can reduce blade performance during operation.

[0012] Another current solution involves setting the rotor blade pitch angle to approximately 90 degrees (the "weathervane" position) when the rotor rotation is prevented by locking pins. At least in some wind conditions, this specific pitch angle reduces the load on the blades. However, when the pitch angle is set to this amount, the locking pins can be subjected to higher loads. The locking pins must be reinforced to withstand these higher loads, such as extra-large locking pins. Furthermore, even in the weathervane position, not all vibrations can be avoided (e.g., if the wind direction changes over time).

[0013] This disclosure provides methods and examples of wind turbines that at least partially address some of the aforementioned drawbacks. Summary of the Invention

[0014] In one aspect, a method is provided for reducing vibration in one or more rotor blades of a wind turbine when the wind turbine is in a stationary state. The method includes: measuring one or more deformation parameters indicating deformation of the one or more blades; and determining the vibration of one or more blades based on the deformation parameters at a dedicated controller for an auxiliary drive system, wherein the dedicated controller for the auxiliary drive system is separate from the wind turbine controller. The method further includes generating an output signal at the dedicated controller to operate the auxiliary drive system to reduce the vibration.

[0015] In this respect, the method can reduce vibration in the blades when the wind turbine is stationary. The method can be performed even without communication between the wind turbine and the remote controller (i.e., even during the commissioning phase). This reduces the risk of high loads or failures between installation and commissioning.

[0016] In addition, the method can reduce the risk of resonance when the wind turbine is stationary, as well as the cost of manual intervention on site.

[0017] In another aspect, a wind turbine is provided, comprising a nacelle, a tower, and rotor blades. The wind turbine includes: a wind turbine controller; one or more sensors for measuring deformation of one or more of the blades; and an auxiliary drive system for driving one or more wind turbine components. The wind turbine further includes a dedicated controller for the auxiliary drive system. The dedicated controller is configured to operate independently of the wind turbine controller. The dedicated controller is also configured to determine the vibration of one or more blades based on the measured deformation and to generate an output signal to operate the auxiliary drive system to reduce vibration when the wind turbine is stationary.

[0018] In another aspect, a method is provided for reducing vibrations in one or more rotor blades of a wind turbine when the turbine is locked during commissioning. The wind turbine has a wind turbine controller and a dedicated pitch controller for a pitch drive system of the wind turbine. The method includes measuring the strain of one or more blades along the edge direction relative to the blade chord. It also includes determining the vibration condition of one or more blades at the dedicated pitch controller based on the measured strain. The method further includes generating an output signal at the dedicated pitch controller to operate the pitch system to reduce the oscillations of one or more rotor blades.

[0019] The advantages derived from this aspect are similar to those mentioned regarding the method in the first aspect.

[0020] Technical Solution 1. A method (200) for reducing vibration in one or more rotor blades (120) of a wind turbine (160) when the wind turbine is in a stopped state, the method comprising: The measurement (201) indicates one or more deformation parameters that indicate the deformation of one or more blades (120); The vibration of one or more of the blades (120) is determined (202) at a dedicated controller (190) for the auxiliary drive system (20, 107) based on the deformation parameters, wherein the dedicated controller (190) for the auxiliary drive system is separate from the wind turbine controller (180); and An output signal (203) is generated at the dedicated controller (190) to operate the auxiliary drive system to reduce the vibration.

[0021] Technical Solution 2. The method according to Technical Solution 1, wherein the blades are arranged at a pitch angle of substantially 0 degrees in a stationary state.

[0022] Technical Solution 3. The method according to any one of Technical Solution 1 to Technical Solution 2, wherein the wind turbine is in a stopped state during the commissioning phase.

[0023] Technical Solution 4. The method according to any one of Technical Solutions 1 to 3, wherein the method further includes: The dedicated controller (190) and the auxiliary drive system (20, 107) are supplied with power from a dedicated power source (140) for the auxiliary drive system.

[0024] Technical Solution 5. The method according to Technical Solution 4, wherein the dedicated power source (140) includes a battery or supercapacitor, the battery or supercapacitor storing a predetermined amount of energy to supply the dedicated controller (190) and the auxiliary drive system (20, 107) during a predetermined time period.

[0025] Technical Solution 6. The method according to any one of Technical Solutions 1 to 5, wherein determining the vibration condition of one or more blades (202) includes: Determine whether the one or more blades oscillate along the edge direction relative to the blade's chord.

[0026] Technical Solution 7. The method according to any one of Technical Solutions 1 to 6, wherein the method further comprises: An output signal is generated at the dedicated controller (190) to operate the auxiliary drive system (20, 107) when the vibration is eliminated, so that the auxiliary drive system returns to the default stop position.

[0027] Technical Solution 8. The method according to any one of Technical Solutions 1 to 7, wherein the auxiliary drive system is a pitch system (107), and the pitch system (107) is used to adjust the pitch angle of one or more of the blades.

[0028] Technical Solution 9. The method according to Technical Solution 8, wherein the output signal includes a command to adjust the blade pitch to a degree in which the vibration is substantially eliminated.

[0029] Technical Solution 10. The method according to any one of Technical Solutions 1 to 7, wherein the auxiliary drive system is a yaw system (20) for rotating the nacelle (161) about the rotation axis (RA) relative to the tower (170) of the wind turbine.

[0030] Technical Solution 11. The method according to Technical Solution 10, wherein the output signal includes a command to adjust the yaw of the wind turbine to a degree in which the vibration is substantially eliminated.

[0031] Technical Solution 12. A wind turbine (160) having a nacelle (161), a tower (170), and rotor blades (120), wherein the wind turbine comprises: Wind turbine controller; One or more sensors (121) are used to measure the deformation of one or more of the blades; An auxiliary drive system (20, 107) is used to drive one or more wind turbine components; A dedicated controller (190) for the auxiliary drive system, the dedicated controller being configured to operate independently of the wind turbine controller (180); The dedicated controller is also configured to determine the vibration of one or more of the blades based on the measured deformation, and to generate an output signal to operate the auxiliary drive system to reduce the vibration when the wind turbine is in a stopped state.

[0032] Technical Solution 13. The wind turbine according to Technical Solution 12, wherein the auxiliary drive system is a pitch system (107), the pitch system (107) being used to adjust the pitch angle of one or more of the blades (120).

[0033] Technical Solution 14. The wind turbine according to Technical Solution 12, wherein the auxiliary drive system is a yaw system (20), the yaw system (20) being used to rotate the nacelle (161) relative to the tower (170) about the rotation axis (RA).

[0034] Technical Solution 15. A wind turbine according to any one of Technical Solutions 12 to 14, wherein the wind turbine includes a dedicated power source (140), the dedicated power source (140) includes a battery or a supercapacitor, the battery or supercapacitor storing a predetermined amount of energy to supply the dedicated controller and the auxiliary drive system during a predetermined time period. Attached Figure Description

[0035] Non-limiting examples of this disclosure will be described below with reference to the accompanying drawings, in which: Figure 1 A perspective view of a wind turbine based on an example is shown; Figure 2 A simplified interior view of the nacelle of a wind turbine, based on an example, is shown. Figure 3 Showing according to an example Figure 1 A perspective view of the rotor blades of a wind turbine; Figure 4 The image shows an example of a sensor used to measure the deformation of a blade. Figure 1 The blades of a wind turbine; Figure 5 A flowchart illustrating a method for reducing vibrations in the rotor blades of a wind turbine, based on an example. Detailed Implementation

[0036] In these figures, the same reference labels are used to indicate matching elements.

[0037] Figure 1 A perspective view of an example wind turbine 160 is shown. As shown, the wind turbine 160 includes a tower 170 extending from a support surface 150, a nacelle 161 mounted on the tower 170, and a rotor 115 coupled to the nacelle 161. The rotor 115 includes a rotatable hub 110 and at least one rotor blade 120 coupled to and extending outward from the hub 110. For example, in the example shown, the rotor 115 includes three rotor blades 120. However, in alternative embodiments, the rotor 115 may include more or fewer than three rotor blades 120. Each rotor blade 120 may be spaced from the hub 110 to allow the rotor 115 to rotate so that kinetic energy can be converted from wind into usable mechanical energy and subsequently into electrical energy. For example, the hub 110 is rotatably coupled to a generator 162. Figure 2The generator 162 is positioned within the nacelle 161 or in a portion forming the nacelle to allow the generation of electrical energy.

[0038] The wind turbine 160 may also include a wind turbine controller 180 located centrally within the nacelle 161. However, in other examples, the wind turbine controller 180 may be located within any other component of the wind turbine 160 or at a location outside the wind turbine. Furthermore, the controller 180 may be communicatively coupled to any number of components of the wind turbine 160 to control the operation of such components.

[0039] In addition, the wind turbine 160 may also include a dedicated controller 190 for an auxiliary drive system. The auxiliary drive system may include a pitch system 107 for adjusting blade pitch. Alternatively, the auxiliary drive system may include a yaw system 20 for rotating the nacelle 161 relative to the tower about an axis of rotation. Details of two examples of auxiliary drive systems are provided below. The dedicated controller 190 may be located centrally within the nacelle 161. However, in other examples, the dedicated controller 190 may be located within any other component of the wind turbine 160 or at a location outside the wind turbine. The dedicated controller 190 may control a single auxiliary drive system or alternatively, at least two of them.

[0040] The dedicated controller 190 can be configured to operate autonomously (i.e., independently of the wind turbine controller 180) in at least some operating conditions. Thus, when the wind turbine controller 180 is in a stopped state, the dedicated controller 190 can at least perform tasks such as receiving and transmitting signals and processing data. For autonomous operation, the dedicated controller 190 can have suitable algorithms for operation before the commissioning phase is completed. In other operating conditions (e.g., normal standard operation), the dedicated controller can communicate and receive control signals from the wind turbine controller 180.

[0041] As used throughout this description, the term "dedicated controller" is preferably intended to refer to any controller entrusted with controlling a single component or a single system. For example, a dedicated pitch controller controls only the pitch of one or more blades and is not configured to control, for example, a yaw system. A dedicated controller may include one or more processors and associated memory devices(s) configured to perform a variety of computer-implemented functions (e.g., performing methods, steps, calculations, etc., and storing related data, as disclosed herein).

[0042] A shutdown condition can refer to those conditions when the wind turbine is not yet commissioned (i.e., the control system is not triggered, communication is unavailable, and the rotor is locked). As used throughout this disclosure, a shutdown condition can also include a wind turbine that is parked but not locked.

[0043] Figure 1The wind turbine 160 can be placed in offshore or onshore locations.

[0044] The wind turbine controller (or “central control system”) 180 may include one or more processors and associated memory devices(s) configured to perform a variety of computer-implemented functions (e.g., performing methods, steps, calculations, etc., and storing relevant data, as disclosed herein). The wind turbine controller can perform various functions, such as receiving, transmitting, and / or executing wind turbine control signals and controlling the overall operation of the wind turbine. The wind turbine controller can be programmable to control overall operation based on indications such as load, wind speed, wind direction, turbulence, component failures, and other information received from sensors.

[0045] The wind turbine controller may also include a communication module to facilitate communication between the controller and the components of the wind turbine, as well as their individual control systems. That is, the wind turbine controller can communicate with the pitch control system, yaw control system, converter control system, and other controllers and components during operation.

[0046] Furthermore, the communication module may include a sensor interface (e.g., one or more analog-to-digital converters) to allow signals transmitted from one or more sensors to be converted into signals that can be understood and processed by the processor. It should be understood that sensors can be communicatively coupled to the communication module using any suitable means (e.g., wired or wireless connections). Thus, the processor can be configured to receive one or more signals from the sensors.

[0047] As used herein, the term "processor" refers not only to integrated circuits considered to be included in a computer in the art, but also to controllers, microcontrollers, microcomputers, programmable logic controllers (PLCs), application-specific integrated circuits (ASICs), and other programmable circuits. Processors are also configured to compute advanced control algorithms and communicate via various Ethernet or serial-based protocols (Modbus, OPC, CAN, etc.). Additionally, the memory device(s) may include memory elements(s) including, but not limited to, computer-readable media (e.g., random access memory (RAM)), computer-readable non-volatile media (e.g., flash memory), floppy disks, optical disc-read-only memory (CD-ROM), magneto-optical discs (MOD), digital versatile discs (DVDs), and / or other suitable memory elements. Such memory devices(s) may be configured to store suitable computer-readable instructions that, when executed by the processor(s), configure the controller to perform various functions (as described herein).

[0048] Figure 2 Show Figure 1A simplified internal view of an example of the nacelle 161 of a wind turbine 160. As shown, a generator 162 may be disposed within the nacelle 161. Generally, the generator 162 may be coupled to the rotor 115 of the wind turbine 160 to generate electrical power from the rotational energy generated by the rotor 115. For example, the rotor 115 may include a main rotor shaft 163 coupled to a hub 110 for rotation therewith. The generator 162 may then be coupled to the rotor shaft 163 such that rotation of the rotor shaft 163 drives the generator 162. For example, in the illustrated embodiment, the generator 162 includes a generator shaft 166 rotatably coupled to the rotor shaft 163 via a gearbox 164.

[0049] It should be understood that the rotor shaft 163, gearbox 164 and generator 162 are generally supported in the nacelle 161 by a support frame or platform 165 positioned on top of the wind turbine tower 170.

[0050] The nacelle 161 is rotatably coupled to the tower 170 via a yaw system 20, enabling the nacelle 161 to rotate about a rotation axis or "yaw axis" RA. The yaw system 20 includes a yaw bearing with two bearing members configured to rotate relative to the other. The tower 170 is coupled to one of the bearing members, and a platform or support frame 165 of the nacelle 161 is coupled to the other bearing member. The yaw system 20 includes a ring gear 21 and a plurality of yaw actuators 22 with a motor 23, a gearbox 24, and a pinion 25 for meshing with the ring gear 21 to rotate one of the bearing members relative to the other.

[0051] The blade 120 is connected to the hub 110 via a pitch bearing 100 located between the blade 120 and the hub 110. The pitch bearing 100 includes an inner ring and an outer ring (in... Figure 2 (As shown in the diagram). The wind turbine blades can be attached to either the inner or outer bearing ring, while the hub is connected at another location. When the pitch system 107 is actuated, the blades 120 can perform a relative rotational motion relative to the hub 110. The rotational motion is performed about the pitch axis PA and can therefore be measured in degrees (as shown in the diagram). Figure 3 (To be discussed in further detail). The inner bearing ring can therefore rotate relative to the outer bearing ring. Figure 2 The pitch system 107 includes a pinion 108 that meshes with a ring gear 109 disposed on an inner bearing ring to rotate the wind turbine blades.

[0052] Although only the pitch axis for a single blade is shown, it should be clear that each blade has such a pitch axis. Furthermore, a single pitch system or multiple separate pitch systems can be used to rotate the blades about their longitudinal axes.

[0053] about Figure 1 For example, the wind turbine 160 also includes a dedicated power source 140, which may include a battery or supercapacitor (not shown) that can store a predetermined amount of energy to supply a dedicated controller 190 and auxiliary drive systems 20, 107 for a predetermined period of time. In other words, the dedicated power source 140 is configured to provide power in a stopped state. In an alternative example, the dedicated power source 140 may include a fuel generator, such as a diesel generator.

[0054] Now refer to Figure 3 The image shows a rotor blade 120 for a wind turbine 160. Furthermore, as shown, the rotor blade 120 has a pressure side 22 and an intake side 24 extending from the blade tip 32 to the blade root 34 between the leading edge 26 and the trailing edge 28. The rotor blade 120 is relative to the rotor hub 115 (… Figure 1 and Figure 2 The rotor blade 120 further defines the pitch axis PA, which is typically perpendicular to the rotor hub 115 and extends through the center of the blade root 34. The pitch angle of the rotor blade 120, or blade pitch (i.e., the angle that determines the view of the rotor blade 120 relative to the airflow passing through the wind turbine 160), can be defined by the rotation of the rotor blade 120 about the pitch axis PA. Additionally, the rotor blade 120 further defines the chord 42 and the wingspan 44. More specifically, as... Figure 3 As shown, the chord 42 can vary at various points along the span 44 of the rotor blade 120. Therefore, for rotor blade 16, a local chord can be defined at any point along the span 44 on blade 16.

[0055] In a stationary state, in a particular example, the blades 120 of the wind turbine 160 may have a pitch angle set to approximately 0 degrees. This blocks the rotor 115, thus preventing it from rotating. The rotor can be blocked by a locking pin (not shown). When the pitch angle is set to the stated amount, the load on the locking pin can be lower than the load when the pitch angle is set to approximately 90 degrees (“weathervane”). Therefore, setting the pitch angle to essentially 0 degrees makes the locking pin less expensive and thus optimizes the wind turbine.

[0056] Furthermore, it may be assumed below that the wind turbine 160 is still not commissioned, i.e., the software or firmware controlling the wind turbine 160 (e.g., via the wind turbine controller 180) is still not operational. Proper communication between the wind turbine 160 and the remote controller remains unavailable. Because there is no triggering remote or local controller, the auxiliary drive system cannot be remotely acted upon.

[0057] According to one aspect, a method is disclosed according to Figure 1 A wind turbine 160 having a nacelle 161, a tower 170, and rotor blades 120. Figure 4 Showing according to an example Figure 1 The wind turbine 160 includes blades 120. In this example, the wind turbine 160 includes a sensor 121 for measuring the deformation of one or more of the blades 120. Such a sensor for measuring deformation may be a strain sensor and may be located at one or more rotor blades 120 to measure the deformation / strain parameters of the blades. The wind turbine 161 also includes auxiliary drive systems 20, 107 for driving the wind turbine components to adjust the load on the blades. The wind turbine 161 also includes a dedicated controller 190 for the auxiliary drive system, and the dedicated controller 190 is configured to operate independently of the wind turbine controller 180. The dedicated controller 190 is also configured to determine the vibration of one or more blades 120 when the wind turbine 160 is in a stopped state and generate an output signal to operate the auxiliary drive system to reduce or counteract the vibration.

[0058] Figure 4 For clarity, the remaining components of the wind turbine 160 are not shown. Figure 4 In the example, strain sensor 121 is a fiber optic strain gauge, which is fixed to the structure of blade 120 to measure strain at any part of the blade (e.g., blade root 34). Therefore, the load on the blade can be calculated based on the measured strain. Strain sensors 121 are interconnected via optical path 122 (e.g., optical fiber). Optical path 122 also allows strain sensors 121 to communicate with sensor interrogation unit 124 or readout unit located in hub 115 or nacelle 161. Sensor interrogation unit 124 is configured to supply optical path 122 with emitted light pulses (not shown) and receive light pulses from strain sensors 121. Interrogation unit 124 is also configured to compare the emitted light pulses with the received light pulses to determine deflection in blade 120.

[0059] The number and location of strain sensors 121 in blade 120 can be varied depending on specific needs.

[0060] The dedicated controller 190 may include or be integrated with the sensor interrogation unit 124. Alternatively, the sensor interrogation unit 124 may be separate from the dedicated controller 190 but may communicate data with it. When the unit 124 and the controller 190 are separated, the dedicated power source 140 also supplies power to the unit 124.

[0061] In some other examples, some strain sensors 121 may be equipped with temperature sensors. Because temperature can affect the operation and characteristics of strain sensor 121, temperature data from the temperature sensor of blade 120 may be taken into account by unit 124 or even by dedicated controller 190.

[0062] Alternatively, in contrast to the example of an optical strain gauge, other sensors 121 capable of indicating deformation of one or more of the blades may be used. Examples include accelerometers or displacement sensors that communicate data with a dedicated controller 190.

[0063] In one example of a wind turbine 160, the auxiliary drive system is a pitch system 107 for adjusting the pitch angle of individual blades, for example... Figure 2 The pitch system 107. Alternatively, the pitch system can adjust the pitch angle of multiple blades simultaneously.

[0064] Alternatively, the auxiliary drive system may include a yaw system 20, which is used to rotate the nacelle 161 relative to the tower 170 about the axis of rotation RA, for example, see Figure 2 .

[0065] Figure 5 A flowchart illustrating a method for reducing vibration in the rotor blades of a wind turbine 200, according to an example. The wind turbine 160 may be... Figure 1 The one shown in the figure, and therefore it includes a wind turbine controller 180 and a dedicated controller 190 for the auxiliary drive system of the wind turbine.

[0066] According to one aspect, a method 200 for reducing vibration in one or more rotor blades of a wind turbine is disclosed. Method 200 is performed when the wind turbine is in a stopped state. Method 200 includes: measuring one or more deformation parameters of one or more blades 201, and determining the vibration of one or more blades 202 based on the deformation parameters at a dedicated controller 190. Method 200 also includes generating an output signal at the dedicated controller 190 to operate an auxiliary drive system to counteract the vibration 203.

[0067] As an example, the deformation parameter indicating the deformation of one or more blades can be a strain parameter.

[0068] In some examples, vibration of one or more blades can be determined when the strain or deformation parameters meet a strain or deformation threshold. For example, a dedicated controller 190 can be configured to determine vibration when the strain parameters meet a strain threshold.

[0069] Due to the flexible nature of blade 120, strain along the edge direction of blade 120 can cause reverse deflection of blade 120 in the opposite direction. As described above, this can produce oscillating displacement of blade 120 when wind turbine 120 is in a stationary state. Therefore, the strain threshold exemplified above can be related to a predefined amplitude threshold for oscillation. When the strain parameter meets the strain threshold, it may mean that the amplitude of oscillation of one or more blades 120 is too large. The vibration condition can then be determined. Figure 4In the diagram, arrow 125 indicates an exemplary direction, followed by the oscillating displacement of blade 120.

[0070] According to some examples, determining the vibration of one or more blades may include processing an input signal that includes strain parameters. The input signal may include the waveform of the strain parameters over time. In an example of method 200, the input signal may be received from sensor interrogation unit 124 or from strain sensor 121.

[0071] The displacement or motion of blade 120 oscillating within a predefined time period may involve frequency. Therefore, some examples of method 200 for processing the input signal may include filtering the input signal and analyzing the frequencies of the input signal that meet a frequency threshold. This allows analysis only of frequencies within a predefined critical range. Alternatively, the input signal may be processed, and its entire spectrum analyzed. Through these two alternatives, an auxiliary drive system can counteract vibration conditions when actually dangerous vibrations occur. Thus, method 200 can distinguish harmful vibrations from normal and acceptable motion.

[0072] In one example, method 200 may further include determining whether one or more blades are in a resonant condition. A dedicated controller 190 can determine the resonant condition of one or more blades. The resonant condition can be determined when the frequency of the input signal meets a resonant threshold. The resonant threshold may relate to frequencies above a frequency threshold. Alternatively, the resonant condition can be determined when the frequency of the input signal and the energy of the resulting vibration increase over a defined time period. Method 200 according to both examples allows operation of an auxiliary drive system to interrupt airflow that causes vortices and stall and to reduce or eliminate resonance.

[0073] In some examples, when method 200 is executed, the blade 120 is arranged in a stationary state with a pitch angle of essentially 0 degrees. This pitch angle involves a simpler locking pin and therefore relates to an optimized configuration of the wind turbine.

[0074] In some other examples, the wind turbine 160 may be in a stationary state during the commissioning phase. An example of a pitch angle of essentially 0 degrees may correspond to the default parking position of the blade 120 when the wind turbine 160 is stationary.

[0075] In some examples, method 200 may also include supplying or providing power to the dedicated controller 190 and the auxiliary drive systems 20, 107 using power from a dedicated power source 140 for the auxiliary drive system.

[0076] According to another example of method 200, the dedicated power source 140 may include a battery or supercapacitor capable of storing a predetermined amount of energy to supply a dedicated controller and auxiliary drive system for a predetermined period of time. Such a period of time may be several weeks or several months. In an alternative example, the dedicated power source 140 may include a fuel generator, such as a diesel generator.

[0077] In some examples, the pitch system can be identified as a Class I component, for which continuous power supply is guaranteed even during installation and even during grid failures.

[0078] In some examples of method 200, determining the vibration of one or more blades may include determining whether the one or more blades oscillate relative to the blade chord in an edge direction. Edge-side oscillations may occur along the chord between the trailing edge 28 and the leading edge 26 of the rotor blade 120.

[0079] In one example of method 200, generating an output signal to operate the auxiliary drive system to counteract vibration may include taking into account the wind direction relative to one or more blades.

[0080] In some additional examples, method 200 may also include determining whether all blades are vibrating in phase. If all blades are vibrating in phase, the outcome regarding the integrity of the wind turbine 160 may be worst, for example, breakage of the rotor's locking pins or a major turbine failure. A dedicated controller 190 may compare the input signals of each of the blades with each other to identify in-phase vibration. An output signal may be generated based on the identification of in-phase vibration, for example, an output signal may be generated to operate the auxiliary drive system to a greater extent. The risk of in-phase vibration may be higher when the pitch angle of the rotor blades 120 is set to substantially 0 degrees compared to a pitch angle of substantially 90 degrees.

[0081] In one example, method 200 may also include generating an output signal at a dedicated controller to operate the auxiliary drive system when the vibration condition is eliminated, so that the auxiliary drive system returns to the default stop position. Because the wind turbine can continue to read strain parameters to confirm whether the vibration condition is still met, method 200 can be implemented in a closed loop.

[0082] In one example of method 200, the auxiliary drive system may include a pitch system 107 for adjusting the pitch of one or more blades according to any of the examples described herein.

[0083] According to some examples, the pitch angle of blade 121 can be adjusted individually for vibration (i.e., when the vibration is determined by a dedicated controller 190). When the wind turbine 160 is in a stationary state, the pitch angle of an individual blade 120 can be changed independently of the pitch angles of other blades, regardless of its azimuth position.

[0084] In another example of method 200, the output signal may include a command to adjust the blade pitch to a degree that counteracts the vibration condition. The blade pitch may be adjusted to a certain degree sufficient to counteract (or at least reduce) the vibration condition. Alternatively, the blade pitch may be adjusted to eliminate the vibration condition. The blade pitch may be adjusted in a single blade or in a combination thereof.

[0085] In some examples of method 200, the blade pitch angle can be adjusted within a range of 10-90 degrees to counteract vibration conditions. When the wind turbine 160 is operating, this adjustment range may exceed the typical pitch range. Such a range allows for changes in the wind flux around the blades to effectively counteract vibration conditions. Alternatively, the blade pitch angle can be adjusted within a range of 15-75 degrees.

[0086] In another example of method 200, the auxiliary drive system may include a yaw system 20 for rotating the nacelle 161 about an axis of rotation relative to the tower 170 of the wind turbine. This yaw system 20 will be based on any of the examples described herein.

[0087] In another example of method 200, the output signal may include a command to adjust the yaw of the wind turbine to a degree in which vibration conditions are substantially eliminated. The yaw system may be adjusted in a similar manner to the pitch system. In some examples, the yaw system may be adjusted as an alternative to the pitch system or even together with the pitch system.

[0088] In some examples of Method 200, the yaw angle can be adjusted within a range of 15–90 degrees (particularly 15–30 degrees). This range allows for changes in the airflow around the blades to reduce or counteract vibration conditions.

[0089] Data based on input and output signals can be recorded in a storage device (not shown) to supply computational simulation models in later stages.

[0090] According to another aspect, a method is disclosed for reducing vibration in one or more rotor blades of a wind turbine when the turbine is locked during the commissioning phase. (As stated above) Figure 1 The wind turbine described herein has a wind turbine controller and a dedicated pitch controller for a pitch drive system of the wind turbine. The method includes measuring the strain of one or more blades relative to the blade chord in the edge direction. The method also includes determining the vibration condition of one or more blades at the dedicated pitch controller based on the measured strain. It further includes, if the vibration condition is determined, generating an output signal at the dedicated pitch controller to operate the pitch drive system to counteract or reduce the oscillations of one or more blades.

[0091] In some examples, the method may also include supplying power from a dedicated power source 140 for the pitch drive system to the dedicated pitch controller 190 and the pitch drive system 107.

[0092] In another example of the method, the output signal may include a command to adjust the blade pitch to a degree that reduces or counteracts vibration conditions. As mentioned above, blade pitch can be adjusted in a single blade or in multiple blades.

[0093] This written description uses examples to disclose the invention (including preferred embodiments) and also enables any person skilled in the art to practice the invention, including making and using any apparatus or system and performing any combined methods. The patentable scope of the invention is defined by the claims and may include other examples that would occur to a person skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that are not different from the literal language of the claims, or if they include equivalent structural elements with no substantial difference from the literal language of the claims. Aspects from the various embodiments described, and other known equivalents for each such aspect, may be mixed and matched by a person skilled in the art to constitute additional embodiments and techniques in accordance with the principles of this application. If reference marks associated with figures are placed in brackets in the claims, they are only intended to increase the comprehensibility of the claims and should not be construed as limiting the scope of the claims.

Claims

1. A method (200) for reducing vibration in one or more rotor blades (120) of a wind turbine (160) during the commissioning phase, the method comprising: The measurement (201) indicates one or more deformation parameters that indicate the deformation of one or more blades (120); The vibration of one or more of the blades (120) is determined (202) based on the deformation parameters at a dedicated controller (190) for the auxiliary drive system (20, 107), wherein the dedicated controller (190) for the auxiliary drive system is separate from the wind turbine controller (180); An output signal (203) is generated at the dedicated controller (190) to operate the auxiliary drive system to reduce the vibration; as well as The dedicated controller (190) and the auxiliary drive system (20, 107) are supplied with power from a dedicated power source (140) for the auxiliary drive system.

2. The method according to claim 1, characterized in that, The blades are arranged at a pitch angle of essentially 0 degrees when stationary.

3. The method according to claim 1, characterized in that, The dedicated power source (140) includes a battery or supercapacitor that stores a predetermined amount of energy to supply the dedicated controller (190) and the auxiliary drive system (20, 107) for a predetermined period of time.

4. The method according to any one of claims 1 to 3, characterized in that, Determining the vibration condition of one or more blades (202) includes: Determine whether the one or more blades oscillate along the edge direction relative to the blade's chord.

5. The method according to any one of claims 1 to 4, characterized in that, The method further includes: An output signal is generated at the dedicated controller (190) to operate the auxiliary drive system (20, 107) when the vibration is eliminated, so that the auxiliary drive system returns to the default stop position.

6. The method according to any one of claims 1 to 5, characterized in that, The auxiliary drive system is a pitch system (107), which is used to adjust the pitch angle of one or more of the blades.

7. The method according to claim 6, characterized in that, The output signal includes a command to adjust the blade pitch to a degree in which the vibration is substantially eliminated.

8. The method according to any one of claims 1 to 5, characterized in that, The auxiliary drive system is a yaw system (20) for rotating the nacelle (161) about the axis of rotation (RA) relative to the tower (170) of the wind turbine.

9. The method according to claim 8, characterized in that, The output signal includes a command to adjust the yaw of the wind turbine to a degree in which the vibration is substantially eliminated.

10. A wind turbine (160) having a nacelle (161), a tower (170), and rotor blades (120), wherein the wind turbine comprises: Wind turbine controller; One or more sensors (121) are used to measure the deformation of one or more of the blades; An auxiliary drive system (20, 107) is used to drive one or more wind turbine components; A dedicated controller (190) for the auxiliary drive system, the dedicated controller being configured to operate independently of the wind turbine controller (180); The dedicated controller is also configured to determine the vibration of one or more of the blades based on the measured deformation, and to generate an output signal to operate the auxiliary drive system to reduce the vibration when the wind turbine is stationary. The wind turbine also includes a dedicated power source (140) for supplying power to the dedicated controller (190) and the auxiliary drive system (20, 107).

11. The wind turbine according to claim 10, characterized in that, The auxiliary drive system is a pitch system (107), which is used to adjust the pitch angle of one or more of the blades (120).

12. The wind turbine according to claim 10, characterized in that, The auxiliary drive system is a yaw system (20), which is used to rotate the nacelle (161) about the axis of rotation (RA) relative to the tower (170).

13. The wind turbine according to any one of claims 10 to 12, characterized in that, The dedicated power source (140) includes a battery or supercapacitor that stores a predetermined amount of energy to supply the dedicated controller and the auxiliary drive system for a predetermined period of time.

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