System and method for monitoring vibrations in drive train of wind turbine

Abstract

The invention relates to a system and method for monitoring vibrations in a drive train of a wind turbine. A method for damping drive train vibrations of a wind turbine. The drive train has at least a rotor and a generator. The method includes receiving a first rotational speed signal at a first position along the drive train, the first rotational speed signal being representative of a rotor speed of the rotor. The method further includes receiving a second rotational speed signal at a second location along the driveline, the second location being leeward of the first location, the second rotational speed signal being a representative of a generator speed of the generator. Further, the method includes determining a speed error based on a comparison of the first rotational speed signal and the second rotational speed signal. Further, the method includes determining a torque deviation signal for the wind turbine when the speed error exceeds a first speed threshold, the torque deviation signal configured to damp driveline vibrations. In addition, the method includes applying a torque deviation signal to the generator to damp driveline vibrations.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to wind turbines, and more particularly to systems and methods for monitoring vibrations in a drive train of a wind turbine. BACKGROUND

[0002] Wind is considered one of the cleanest and most environmentally friendly energy sources currently available, and wind turbines have gained increasing interest in this regard. A modern wind turbine typically includes a tower, a nacelle mounted on top of the tower, a rotor with one or more rotor blades mounted to the nacelle, and a drive train within the nacelle. The drive train typically includes various drive train components, such as a generator and a gearbox. The nacelle includes a rotor assembly coupled to the gearbox and coupled to the generator. In many wind turbines, the generator and the gearbox are mounted to a bedplate within the nacelle via one or more torque arms. As such, the one or more rotor blades capture kinetic energy of the wind using known airfoil principles. The rotor blades transmit the kinetic energy in the form of rotational energy to turn a shaft that couples the rotor blades to the gearbox, or directly to the generator if no gearbox is used. The generator then converts the mechanical energy to electrical energy that can be deployed to a utility grid.

[0003] Often, a wind turbine can be equipped with various sensors for determining rotational speed conditions of the drive train, such as generator speed. In an example, the generator speed can be passed to a bandpass filter that outputs a drive train vibration speed, which can be used to implement certain dynamic control functions, such as damping drive train vibrations. However, newer, larger wind turbines have lower drive train frequencies, which increases the complexity in designing a bandpass filter that is able to decouple drive train vibrations from drive train speed transients, and can cause the bandpass filtered generator speed to no longer be a good representation of the drive train vibrations. If the bandpass filtered generator speed is not a good representation of the drive train vibrations, the wind turbine can become damaged. For example, in the case where the bandpass filtered generator speed is not a good representation of the drive train vibrations, the turbine controller can apply a modulating torque to the generator that is excessive or insufficient in the case of actual drive train vibrations, which can result in equipment overload.

[0004] As such, the present disclosure is directed to systems and methods that detect a deviation between speed measurements at locations along the drive train from the rotor to the generator and implement control actions in order to avoid the aforementioned problems. SUMMARY

[0005] Aspects and advantages of the disclosure will be set forth in part in the following description, or can become apparent to practice the present disclosure, or can be learned by practice of the present disclosure.

[0006] In one aspect, this disclosure relates to a method for damping vibrations in a drive system of a wind turbine. The drive system has at least a rotor and a generator. The method includes receiving a first rotational speed signal at a first position along the drive system, the first rotational speed signal being representative of the rotor speed. The method also includes receiving a second rotational speed signal at a second position along the drive system, the second position being leeward of the first position, the second rotational speed signal being representative of the generator speed. Furthermore, the method includes determining a speed error based on a comparison of the first and second rotational speed signals. Additionally, the method includes determining a torque deviation signal for the wind turbine when the speed error exceeds a first speed threshold, the torque deviation signal being configured to dampen drive system vibrations. Furthermore, the method includes applying the torque deviation signal to the generator to dampen drive system vibrations.

[0007] In another aspect, this disclosure relates to a drive system assembly for a wind turbine. The drive system assembly includes a rotor shaft for coupling to a rotor of the wind turbine, a gearbox coupled to the rotor shaft, a generator coupled to the gearbox via a generator shaft, and a controller for controlling the operation of the wind turbine. The controller includes at least one processor configured to perform a plurality of operations, including but not limited to: receiving a first rotational speed signal at a first position along the drive system, the first rotational speed signal being representative of the rotor speed; receiving a second rotational speed signal at a second position along the drive system, the second position being leeward of the first position, the second rotational speed signal being representative of the generator speed; determining a speed error based on a comparison of the first and second rotational speed signals; determining a torque deviation signal for the wind turbine when the speed error exceeds a first speed threshold, the torque deviation signal being configured to dampen drive system vibration; and applying the torque deviation signal to the generator to dampen drive system vibration.

[0008] Technical Solution 1. A method for damping the vibration of a drive system of a wind turbine, said drive system having at least a rotor and a generator, the method comprising: A first rotational speed signal is received at a first position along the drive system, the first rotational speed signal being representative of the rotor speed of the rotor; A second rotational speed signal is received at a second position along the drive system, the second position being downwind of the first position, and the second rotational speed signal being representative of the generator speed of the generator; The speed error is determined by comparing the first rotational speed signal and the second rotational speed signal; When the speed error exceeds a first speed threshold, a torque deviation signal for the wind turbine is determined, the torque deviation signal being configured to dampen the vibration of the drive system; and The torque deviation signal is applied to the generator to dampen the vibration of the drive system.

[0009] Technical Solution 2. The method according to Technical Solution 1 further includes shutting down the wind turbine when the speed error exceeds a second speed threshold, wherein the second speed threshold is greater than the first speed threshold.

[0010] Technical Solution 3. The method according to Technical Solution 2, wherein the second speed threshold is a variable threshold that depends on the speed error and the time period.

[0011] Technical Solution 4. The method according to Technical Solution 2, wherein shutting down the wind turbine when the speed error exceeds the second speed threshold further includes: Determine the speed error during the time period; and The speed error is compared with a second speed threshold, which is output by the function in response to the time period input to the function.

[0012] Technical Solution 5. The method according to Technical Solution 1 further includes determining the first rotational speed signal via a rate gyroscope.

[0013] Technical Solution 6. The method according to Technical Solution 5, wherein the rate gyroscope is rigidly connected to the rotor.

[0014] Technical Solution 7. The method according to Technical Solution 1, wherein determining the speed error based on the comparison between the first rotational speed signal and the second rotational speed signal further comprises: Determine the difference between the first rotational speed signal and the second rotational speed signal.

[0015] Technical Solution 8. The method according to Technical Solution 1 further includes: scaling the second rotational speed signal based on the gearbox ratio before determining the speed error.

[0016] Technical Solution 9. The method according to Technical Solution 1, wherein the first speed threshold is a variable threshold that depends on at least one of rotor speed, torque, wind speed, or a function thereof.

[0017] Technical Solution 10. The method according to Technical Solution 1, wherein the first speed threshold is a fixed threshold.

[0018] Technical Solution 11. A drive system assembly for a wind turbine, the drive system assembly comprising: Rotor shaft, which is used to connect to the rotor of the wind turbine; A gearbox, which is connected to the rotor shaft; A generator, which is connected to the gearbox via a generator shaft; and A controller for controlling the operation of the wind turbine, the controller including at least one processor configured to perform a plurality of operations, the plurality of operations including: A first rotational speed signal is received at a first position along the drive system, the first rotational speed signal being representative of the rotor speed of the rotor; A second rotational speed signal is received at a second position along the drive system, the second position being downwind of the first position, and the second rotational speed signal being representative of the generator speed of the generator; The speed error is determined by comparing the first rotational speed signal and the second rotational speed signal; When the speed error exceeds a first speed threshold, a torque deviation signal for the wind turbine is determined, the torque deviation signal being configured to cause vibration of the damped drive system; and The torque deviation signal is applied to the generator to dampen the vibration of the drive system.

[0019] Technical Solution 12. The drive system component according to Technical Solution 11, wherein the plurality of operations further include: The wind turbine is shut down when the speed error exceeds a second speed threshold, where the second speed threshold is greater than the first speed threshold.

[0020] Technical Solution 13. The drive system component according to Technical Solution 12, wherein the second speed threshold is a variable threshold that depends on the speed error and the time period.

[0021] Technical Solution 14. The drive system component according to Technical Solution 12, wherein shutting down the wind turbine when the speed error exceeds a second speed threshold further comprises: Determine the speed error during the time period; and The speed error is compared with a second speed threshold, which is output by the function in response to the time period input to the function.

[0022] Technical Solution 15. The drive system component according to Technical Solution 11, wherein the plurality of operations further includes determining the first rotational speed signal via a rate gyroscope.

[0023] Technical Solution 16. The drive system assembly according to Technical Solution 15, wherein the rate gyroscope is rigidly connected to the rotor.

[0024] Technical Solution 17. The drive system assembly according to Technical Solution 11, wherein determining the speed error based on the comparison of the first rotational speed signal and the second rotational speed signal further includes: Determine the difference between the first rotational speed signal and the second rotational speed signal.

[0025] Technical Solution 18. The drive system assembly according to Technical Solution 11, wherein the plurality of operations further includes: scaling the second rotational speed signal based on the gearbox ratio before determining the speed error.

[0026] Technical Solution 19. The drive system component according to Technical Solution 11, wherein the first speed threshold is a variable threshold that depends on at least one of rotor speed, torque, wind speed, or a function thereof.

[0027] Technical solution 20. The drive system component according to technical solution 11, wherein the first speed threshold is a fixed threshold.

[0028] These and other features, aspects, and advantages of this disclosure will become more readily understood with reference to the following description and the appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and, together with the description, serve to illustrate the principles of the disclosure. Attached Figure Description

[0029] The complete and implementable disclosure (including its best mode) of this disclosure is set forth in the description with reference to the accompanying drawings, in which: Figure 1 The figure shows a perspective view of a wind turbine according to an embodiment of the present disclosure; Figure 2 The figure shows a perspective interior view of the nacelle of a wind turbine according to an embodiment of the present disclosure; Figure 3 The illustration shows a schematic diagram of an embodiment of a suitable component that can be included in a wind turbine controller according to the present disclosure; and Figure 4 The illustration is a flowchart of an embodiment of a method for detecting and responding to a speed deviation at a position along the drive system of a wind turbine, according to the present disclosure. Detailed Implementation

[0030] Reference will now be made in detail to embodiments of the present disclosure, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of interpretation rather than limitation of the present disclosure. Indeed, it will be apparent to those skilled in the art that various modifications and variations may be made to the present disclosure without departing from its scope. For example, features illustrated or described as part of an embodiment may be used with another embodiment to produce yet another embodiment. Therefore, it is intended that the present disclosure cover such modifications and variations as fall within the scope of the appended claims and their equivalents.

[0031] Generally, this disclosure relates to systems and methods for detecting drivetrain speed deviations and responding to such deviations in a manner that limits the vibration of a wind turbine. A high-fidelity encoder can be used to detect the generator speed of a generator within a wind turbine. Drivetrain vibrations are typically determined by bandpass filtering the generator speed. Active damping and monitoring functions can then be performed based on the determined drivetrain vibrations. However, in larger drivetrains, generator speed alone may not be a good representative of drivetrain vibrations due to lower drivetrain frequencies. Thus, high-fidelity encoders can be used at additional locations along the drivetrain to determine the speed error between these locations. The speed error is used as a measure of drivetrain vibrations, which allows for simpler, more accurate, and more robust implementation of active damping and monitoring functions. Therefore, the systems and methods of this disclosure are configured to apply a torque deviation signal to modulate drivetrain vibrations based on the detection of a speed error above a certain threshold between locations along the drivetrain from the rotor to the generator.

[0032] Now refer to the attached diagram, Figure 1 The figure shows a perspective view of an embodiment of a wind turbine 10 according to the present disclosure. As shown, the wind turbine 10 includes a tower 12 extending from a support surface 14, a nacelle 16 mounted on the tower 12, and a rotor 18 coupled to the nacelle 16. The rotor 18 includes a rotatable hub 20 and at least one rotor blade 22 coupled to and extending outward from the hub 20. For example, in the illustrated embodiment, the rotor 18 includes three rotor blades 22. However, in alternative embodiments, the rotor 18 may include more or fewer than three rotor blades 22. Each rotor blade 22 may be spaced apart around the hub 20 to allow the rotor 18 to rotate, thereby enabling kinetic energy to be converted from wind into usable mechanical energy and subsequently into electrical energy. For example, the hub 20 may be rotatably coupled to an electric generator 24 located within the nacelle 16. Figure 2 This allows for the generation of electrical energy.

[0033] Now for reference Figure 2The illustration shows a simplified internal view of an embodiment of the nacelle 16 of a wind turbine 10. As shown, the wind turbine 10 includes a generator 24 disposed within the nacelle 16. Generally, the generator 24 can be coupled to the rotor 18 of the wind turbine 10 to generate electrical power from the rotational energy generated by the rotor 18. For example, the rotor 18 may include a rotor shaft 40 coupled to a hub 20 for rotating together with the hub 20. The generator 24 can then be coupled to the rotor shaft 40 such that rotation of the rotor shaft 40 drives the generator 24. For example, in the illustrated embodiment, the generator 24 includes a generator shaft 42 rotatably coupled to the rotor shaft 40 via a gearbox 44. As generally understood, the rotor shaft 40 can provide a low-speed, high-torque input to the gearbox 44 in response to rotation of the rotor blades 22 and the hub 20. The gearbox 44 can then be configured to convert the low-speed, high-torque input into a high-speed, low-torque output to drive the generator shaft 42 and thus the generator 24. However, in other embodiments, it should be appreciated that the generator shaft 42 may be rotatably and directly coupled to the rotor shaft 40. Alternatively, the generator 24 may be directly and rotatably coupled to the rotor shaft 40. Such a component may be generally referred to herein as drive system 50 or drive system assembly.

[0034] It should be appreciated that the rotor shaft 40 can be generally supported within the nacelle 16 by a support frame or base plate 46 positioned on top of the wind turbine tower 12. For example, the rotor shaft 40 can be supported by the base plate 46 via a pair of bolster blocks mounted to the base plate 46.

[0035] like Figure 1 and Figure 2 As shown, the wind turbine 10 may also include a turbine control system or turbine controller 26 within the nacelle 16. For example, as Figure 2 As shown, the turbine controller 26 is housed within a control cabinet 27 that is mounted to a portion of the nacelle 16. However, it should be appreciated that the turbine controller 26 may be located on the wind turbine 10 or anywhere within the wind turbine 10, on the support surface 14. Figure 1 The turbine controller 26 can be configured to control various operating modes (e.g., start-up or shutdown sequences) and / or components of the wind turbine 10 at any location on the turbine or substantially at any other location.

[0036] like Figure 2As shown, the wind turbine 10 may further include at least one pitch adjustment mechanism 32 for each of the rotor blades 22, the at least one pitch adjustment mechanism 32 being configured to rotate each rotor blade 22 about its pitch axis 34. In an embodiment, each pitch adjustment mechanism 32 may include a pitch drive motor 33 (e.g., any suitable electric, hydraulic, or pneumatic motor), a pitch drive gearbox 35, and a pitch drive pinion 37. In such an embodiment, the pitch drive motor 33 may be coupled to the pitch drive gearbox 35 such that the pitch drive motor 33 applies mechanical force to the pitch drive gearbox 35. Similarly, the pitch drive gearbox 35 may be coupled to the pitch drive pinion 37 for rotation therewith. The pitch drive pinion 37 may then be rotatably engaged with a pitch bearing 36 coupled between the hub 20 and the corresponding rotor blade 22 such that rotation of the pitch drive pinion 37 causes rotation of the pitch bearing 36. Therefore, in such an embodiment, the rotation of the pitch drive motor 33 drives the pitch drive gearbox 35 and the pitch drive pinion 37, thereby causing the pitch bearing 36 and the rotor blades 22 to rotate about the pitch axis 34. Similarly, the wind turbine 10 may include one or more yaw drive mechanisms 38 communicatively coupled to the controller 26, wherein each yaw drive mechanism(s) 38 is configured to change the angle of the nacelle 16 relative to the wind (e.g., by engaging the yaw bearing 56 of the wind turbine 10 and rotating the nacelle 16 about the yaw axis 39).

[0037] Furthermore, as shown, the turbine controller 26 can also be controlled by a separate or integrated pitch controller 30 ( Figure 2 It is communicatively connected to each pitch adjustment mechanism 32 of the wind turbine 10 for controlling and / or modifying the pitch angle of each corresponding rotor blade 22 (i.e., determining the angle of the rotor blade 22 with respect to the wind direction 28).

[0038] In addition, such as Figure 2 As shown, one or more sensors 51, 52 may be mounted on the wind turbine 10. More specifically, as shown, shaft sensor 51 may be communicatively coupled to rotor shaft 40 and / or rotor 18 to monitor its speed. Additionally, as shown, generator sensor 52 may be communicatively coupled to generator 24 to monitor its speed. Other embodiments may include any other suitable type of sensor, such as a wind vane, accelerometer, or the like. Thus, sensors 51, 52 may further communicate with controller 26 and provide information to controller 26.

[0039] It should also be appreciated that, as used herein, the term “monitoring” and its variations indicate that various sensors of the wind turbine 10 can be configured to provide direct measurements of the monitored parameters and / or indirect measurements of such parameters. Thus, the sensors described herein can, for example, be used to generate signals relating to the monitored parameters, which can then be utilized by the controller 26 to determine the condition.

[0040] Now for reference Figure 3 The illustration shows a block diagram of an embodiment of suitable components that may be included within a controller 26 according to the present disclosure. As shown, the controller(s) 26 may include one or more processors 60 and associated memory devices(s) 62 configured to perform various computer-implemented functions (e.g., performing methods, steps, calculations, etc., as disclosed herein and storing related data).

[0041] Additionally, the controllers 26 may also include a communication module 64 to facilitate communication between the controllers 26 and various components of the wind turbine 10. Furthermore, the communication module 64 may include a sensor interface 66 (e.g., one or more analog-to-digital converters) to allow signals transmitted from one or more sensors 51, 52 to be converted into signals that can be understood and processed by the processor 60. It should be appreciated that the sensors 51, 52 can be communicatively coupled to the communication module 64 using any suitable means. For example, such as... Figure 3 As shown, sensors 51 and 52 are connected to sensor interface 66 via a wired connection. However, in other embodiments, sensors 51 and 52 may be connected to sensor interface 66 via a wireless connection (such as by using any suitable wireless communication protocol known in the art).

[0042] As used herein, the term "processor" refers not only to integrated circuits included in a computer as known in the art, but also to controllers, microcontrollers, microcomputers, programmable logic controllers (PLCs), application-specific integrated circuits (ASICs), and other programmable circuits. Additionally, the memory device(s) 62 may generally 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, compact disc-read-only memory (CD-ROM), magneto-optical disks (MOD), digital versatile discs (DVDs), and / or other suitable memory elements. Such memory device(s) 62 may generally be configured to store suitable computer-readable instructions that, when implemented by the processor(s) 60, configure the controller(s) 26 to perform various functions, including but not limited to transmitting suitable control signals to perform multiple correction actions in response to a distance signal exceeding a predetermined threshold, as described herein, and various other suitable computer-implemented functions.

[0043] Now for reference Figure 4 The illustration shows a flowchart of an embodiment of a method 100 for detecting and damping vibrations in the drive system of a wind turbine. Method 100 may use, for example, the above-referenced... Figures 1 to 3 The wind turbine 10 and controller 26 are discussed for implementation. For illustrative and discussion purposes, Figure 4 The steps are described in a specific order. Those skilled in the art will understand, using the disclosure provided herein, that various steps of the method 100 disclosed herein or any other method can be adapted, modified, rearranged, performed simultaneously, or modified in a variety of ways without departing from the scope of this disclosure.

[0044] As shown at (102), method 100 includes receiving (e.g., via a controller (such as controller 26)) a first rotational speed signal at a first position along the drive system 50. For example, in an embodiment, the first rotational speed signal is representative of the rotor speed of the rotor 18 of the wind turbine 10. Therefore, in an embodiment, the first rotational speed signal may be measured by a sensor 51 mounted in the wind turbine 10 (such as on the rotor 18).

[0045] Furthermore, in embodiments, the first position may correspond to a position on or within the hub 20 and / or on the rotor shaft 40. In other words, method 100 may include receiving a first rotational speed signal via a sensor 51 mounted in the hub 20 of the wind turbine 10 or mounted at a point rigidly connected to the hub 20 (e.g., on the rotor shaft 40). The sensor 51 may be, for example, any suitable type of sensor, such as a bolt counter, slip ring sensor, or tachometer sensor. As an example, the sensor 51 may be one or more rate gyroscopes (also referred to as rate gyroscopes). As used herein, a rate gyroscope generally refers to a gyroscope that indicates the rate of change of an angle with respect to time. If the gyroscope has only one constant-level ring (and therefore only one free plane), the gyroscope may be adapted to act as a rate gyroscope for measuring the rate of angular motion. Additionally, the rate gyroscope described herein may also encompass microelectromechanical systems (MEMS) gyroscopes.

[0046] Furthermore, while rate gyroscopes (multiple gyroscopes) as described herein are generally effective in detecting rapid changes in velocity, they may have biases that can drift over time (e.g., due to temperature and / or various other factors) (i.e., the DC offset measured at ambient temperature when the rate gyroscope is stationary). Bias can also exist because it may be difficult to calibrate the rate gyroscopes (multiple gyroscopes) after power has been supplied to them, since the rate gyroscopes (multiple gyroscopes) are rarely truly stationary. Therefore, in embodiments, the first rotational velocity signal may be processed to account for biases in the first rotational velocity signal resulting from the use of one or more rate gyroscopes. In additional embodiments, the first rotational velocity signal may be processed by high-pass filtering to account for biases in the first rotational velocity signal resulting from the use of one or more rate gyroscopes.

[0047] Still referencing Figure 4 As shown at (104), method 100 includes receiving a second rotational speed signal from different second positions along the drive system 50 (e.g., via controller 26). For example, in an embodiment, the second position may be downwind of the first position. Furthermore, in an embodiment, the second rotational speed signal is representative of the generator speed of generator 24. Therefore, in an embodiment, the second rotational speed signal may be measured by a sensor 52 mounted in the wind turbine 10 (such as on generator 24). In an embodiment, any suitable sensor may be used to measure the second rotational speed signal, such as a bolt counter, slip ring sensor, tachometer sensor, and / or one or more additional rate gyroscopes.

[0048] Furthermore, in an embodiment, the second position may correspond to a position on the generator 24. In other words, method 100 may include receiving a second rotational speed signal via a sensor 52 mounted on the generator 24 or mounted at a point rigidly connected to the generator 24 (e.g., on the generator shaft 42). Thus, the first and second rotational speed signals are collected at the ends of the drive system 50 (e.g., at the rotor 18 and at the generator 24).

[0049] Furthermore, as shown at (106), method 100 includes determining (e.g., via controller 26) a speed error based on a comparison of a first rotational speed signal and a second rotational speed signal. For example, in one embodiment, determining the speed error based on a comparison of the first rotational speed signal and the second rotational speed signal may include determining the difference between the first rotational speed signal and the second rotational speed signal. As another example, in one embodiment, determining the speed error based on a comparison of the first rotational speed signal and the second rotational speed signal may include processing (e.g., according to known signal processing techniques such as encoding) the first rotational speed signal and the second rotational speed signal and then determining the difference or ratio of the processed first rotational speed signal and the second rotational speed signal. The speed error may, for example, be a signed value (i.e., a numerical value represented by a positive or negative sign) representing the comparison of the first rotational speed signal and the second rotational speed signal. As another example, the speed error may be an absolute value representing the comparison of the first rotational speed signal and the second rotational speed signal.

[0050] More specifically, in an embodiment, method 100 may include scaling (e.g., via controller 26) a second rotational speed signal based on a gearbox ratio before determining the speed error. In such an embodiment, the gearbox ratio may be specified based on the dimensions of the gearbox 44 arranged in the drive system 50. The gearbox ratio may be stored (e.g., stored in a memory device 62 of controller 26). The second rotational speed signal may be multiplied by the gearbox ratio. In another embodiment, the first rotational speed signal may be divided by the gearbox ratio. Scaling one of the rotational speed signals based on the gearbox ratio allows for a more robust determination of the speed error by taking into account the difference between the rotor speed and the generator speed introduced via gearbox 44.

[0051] In addition, such as Figure 4As shown at (108), method 100 includes determining (e.g., via controller 26) a torque deviation signal for the wind turbine 10 when the speed error exceeds a first speed threshold. This torque deviation signal is configured to dampen drive system vibrations. More specifically, in embodiments, the torque deviation signal may be configured to modulate drive system vibrations to reduce the speed error by applying torque in a direction used to offset the speed error (e.g., applying torque clockwise when the first rotational speed signal is greater than the second rotational speed signal, or applying torque counterclockwise when the second rotational speed signal is greater than the first rotational speed signal). Determining the torque deviation signal may, for example, include accessing (e.g., via controller 26) a lookup table or similar entity that associates various torque deviation signals with various speed errors (e.g., stored in memory device 62 of controller 26). In such an example, when the speed error exceeds the first speed threshold, controller 26 may then select the torque deviation signal associated with the speed error from the lookup table. As another example, the torque deviation signal can be determined based on calculations (e.g., via controller 26) that modulate the vibration introduced by the speed error in order to reduce the torque of the speed error (e.g., according to known techniques).

[0052] In one embodiment, the first speed threshold may be a variable threshold that depends on at least one of rotor speed, torque, wind speed, or a function thereof. In another embodiment, the first speed threshold may be a fixed threshold. In such an embodiment, the first speed threshold may be determined empirically (e.g., based on tests and / or simulations to determine a speed error above which applied torque can modulate vibrations introduced by the speed error (e.g., due to the design and / or sizing of the wind turbine 10 and / or its components)). The first speed threshold may specify the minimum speed error that can be reduced via torque modulation. Thus, the first speed threshold may be configured to constrain the application of a torque deviation signal to prevent undesirable torque modulation of the generator 24. By way of example, the first speed threshold may be zero. As another example, the first speed threshold may be a non-zero value.

[0053] Still referencing Figure 4 As shown at (110), method 100 includes applying a torque deviation signal (e.g., via controller 26) to generator 24 to dampen drive system vibrations. For example, in one embodiment, the torque deviation signal is applied to generator 24 (e.g., according to known torque modulation techniques) to dampen drive system vibrations by reducing speed errors. More specifically, the torque deviation signal may be configured to reduce speed errors to below a first speed threshold.

[0054] In another embodiment, method 100 may include shutting down wind turbine 10 when the speed error exceeds a second speed threshold. In such an embodiment, the second speed threshold is greater than a first speed threshold. In an embodiment, the second threshold may be a variable threshold that depends on the speed error and a time period. Method 100 may include determining the speed error for a time period (e.g., based on the envelope of the speed error during the time period). Method 100 may further include comparing the speed error (e.g., the envelope) with a second speed threshold that may be output by a function in response to a time period input to a function. Additionally or alternatively, the second threshold may be a variable threshold that further depends on at least one of rotor speed, torque, wind speed, or a function thereof. In another embodiment, the second threshold may be a fixed threshold. In such an embodiment, the second speed threshold may be determined empirically (e.g., based on tests and / or simulations to determine that at speed errors above which wind turbine 10 and / or its components may experience excessive equipment overload, regardless of whether torque is applied to modulate vibrations introduced by the speed error (e.g., due to the design and / or size of wind turbine 10 and / or its components)). The second speed threshold can specify the maximum speed error that can be reduced via torque modulation without subjecting the wind turbine 10 and / or its components to excessive equipment overload. Therefore, the second speed threshold can be configured to constrain the application of the torque deviation signal to prevent excessive equipment overload.

[0055] Furthermore, those skilled in the art will recognize the interchangeability of various features from different embodiments. Similarly, the various method steps and features described, as well as other known equivalents for each such method and feature, can be mixed and matched by those skilled in the art to construct additional systems and techniques in accordance with the principles of this disclosure. Of course, it is to be understood that not all such objects or advantages described above may necessarily be achieved according to any particular embodiment. Therefore, for example, those skilled in the art will recognize that the systems and techniques described herein may be embodied or performed in a manner that achieves or optimizes one or more advantages as taught herein, but not necessarily other objects or advantages as may be taught or suggested herein.

[0056] The various aspects and embodiments of this disclosure are defined by the following terms: A method for damping vibrations of a drive system of a wind turbine, the drive system having at least a rotor and a generator, the method comprising: receiving a first rotational speed signal at a first position along the drive system, the first rotational speed signal being representative of the rotor speed; receiving a second rotational speed signal at a second position along the drive system downwind of the first position, the second rotational speed signal being representative of the generator speed; determining a speed error based on a comparison of the first rotational speed signal and the second rotational speed signal; determining a torque deviation signal for the wind turbine when the speed error exceeds a first speed threshold, the torque deviation signal being configured to dampen drive system vibrations; and applying the torque deviation signal to the generator to dampen drive system vibrations.

[0057] The method according to any of the foregoing provisions further includes shutting down the wind turbine when the speed error exceeds a second speed threshold, which is greater than the first speed threshold.

[0058] According to any of the foregoing provisions, the second speed threshold is a variable threshold that depends on the speed error and the time period.

[0059] According to any of the foregoing provisions, the method of shutting down the wind turbine when the speed error exceeds a second speed threshold further includes: determining the speed error during a time period; and comparing the speed error with a second speed threshold, which is output by a function in response to the time period input to the function.

[0060] The method according to any of the foregoing provisions further includes determining the first rotational speed signal via a rate gyroscope.

[0061] According to any of the foregoing provisions, the rate gyroscope is rigidly connected to the rotor.

[0062] According to any of the foregoing provisions, the method of determining the speed error based on the comparison of the first rotational speed signal and the second rotational speed signal further includes: determining the difference between the first rotational speed signal and the second rotational speed signal.

[0063] The method according to any of the foregoing clauses further includes: scaling the second rotational speed signal based on the gearbox ratio before determining the speed error.

[0064] According to any of the foregoing provisions, the first speed threshold is a variable threshold that depends on at least one of rotor speed, torque, wind speed, or a function thereof.

[0065] According to any of the foregoing provisions, the first speed threshold is a fixed threshold.

[0066] A drive system assembly for a wind turbine includes: a rotor shaft for coupling to a rotor of the wind turbine; a gearbox coupled to the rotor shaft; a generator coupled to the gearbox via a generator shaft; and a controller for controlling the operation of the wind turbine. The controller includes at least one processor configured to perform a plurality of operations, the plurality of operations including: receiving a first rotational speed signal at a first position along the drive system, the first rotational speed signal being representative of the rotor speed; receiving a second rotational speed signal at a second position along the drive system downwind of the first position, the second rotational speed signal being representative of the generator speed; determining a speed error based on a comparison of the first rotational speed signal and the second rotational speed signal; determining a torque deviation signal for the wind turbine when the speed error exceeds a first speed threshold, the torque deviation signal being configured to dampen drive system vibration; and applying the torque deviation signal to the generator to dampen the drive system vibration.

[0067] According to any of the foregoing provisions, the drive system component, wherein multiple operations further include: shutting down the wind turbine when the speed error exceeds a second speed threshold, the second speed threshold being greater than the first speed threshold.

[0068] According to any of the foregoing provisions, the drive system component, wherein the second speed threshold is a variable threshold that depends on the speed error and the time period.

[0069] According to any of the foregoing provisions, the shutdown of the wind turbine when the speed error exceeds a second speed threshold further includes: determining the speed error during a time period; and comparing the speed error with a second speed threshold, which is output by a function in response to the time period input to the function.

[0070] According to any of the foregoing provisions, the drive system component, wherein multiple operations further include determining a first rotational speed signal via a rate gyroscope.

[0071] Drive system components according to any of the foregoing terms, wherein the rate gyroscope is rigidly connected to the rotor.

[0072] According to any of the foregoing provisions, the determination of speed error based on a comparison of a first rotational speed signal and a second rotational speed signal further includes: determining the difference between the first rotational speed signal and the second rotational speed signal.

[0073] According to any of the foregoing provisions, the drive system component, wherein multiple operations further include: scaling a second rotational speed signal based on a gearbox ratio before determining a speed error.

[0074] According to any of the foregoing provisions, the drive system component wherein the first speed threshold is a variable threshold that depends on at least one of rotor speed, torque, wind speed, or a function thereof.

[0075] Drive system components according to any of the foregoing terms, wherein the first speed threshold is a fixed threshold.

[0076] This written description uses examples to disclose this disclosure (including the best mode) and also enables any person skilled in the art to practice this disclosure (including making and using any apparatus or system and performing any incorporated methods). The patentability of this disclosure 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 include structural elements that are not different from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims.

Claims

1. A method for damping the vibration of a drive system of a wind turbine, said drive system having at least a rotor and a generator, the method comprising: A first rotational speed signal is received at a first position along the drive system, the first rotational speed signal being representative of the rotor speed of the rotor; A second rotational speed signal is received at a second position along the drive system, the second position being downwind of the first position, and the second rotational speed signal being representative of the generator speed of the generator; The speed error is determined by comparing the first rotational speed signal and the second rotational speed signal; When the speed error exceeds a first speed threshold, a torque deviation signal for the wind turbine is determined, and the torque deviation signal is configured to dampen the vibration of the drive system. as well as The torque deviation signal is applied to the generator to dampen the vibration of the drive system.

2. The method according to claim 1, further comprising shutting down the wind turbine when the speed error exceeds a second speed threshold, wherein the second speed threshold is greater than the first speed threshold.

3. The method according to claim 2, wherein, The second speed threshold is a variable threshold that depends on the speed error and the time period.

4. The method according to claim 2, wherein, Shutting down the wind turbine when the speed error exceeds the second speed threshold further includes: Determine the speed error during the time period; and The speed error is compared with a second speed threshold, which is output by the function in response to the time period input to the function.

5. The method of claim 1, further comprising determining the first rotational speed signal via a rate gyroscope.

6. The method according to claim 5, wherein, The rate gyroscope is rigidly connected to the rotor.

7. The method according to claim 1, wherein, Determining the speed error based on the comparison between the first rotational speed signal and the second rotational speed signal further includes: Determine the difference between the first rotational speed signal and the second rotational speed signal.

8. The method of claim 1, further comprising: Before determining the speed error, the second rotational speed signal is scaled based on the gearbox ratio.

9. The method according to claim 1, wherein, The first speed threshold is a variable threshold that depends on at least one of rotor speed, torque, wind speed, or a function thereof.

10. The method according to claim 1, wherein, The first speed threshold is a fixed threshold.

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