System and method for predicting optimal start-up of yaw drive system of wind turbine

Abstract

The invention relates to a system and method for predicting optimal start-up of a yaw drive system of a wind turbine. A method for protecting one or more components of a yaw system of a wind turbine includes monitoring one or more load signals indicative of a yaw moment of a rotor of the wind turbine. The method also includes evaluating one or more load signals indicative of a yaw moment of the rotor. Further, the method includes predicting an optimal start-up time for the yaw system based on the evaluated one or more load signals. Further, the method includes starting the yaw system at the optimal start-up time to minimize a load of the yaw system of the wind turbine.

Description

Technical Field

[0001] The present disclosure relates generally to wind turbines, and more particularly to systems and methods for predicting an optimal activation point of a yaw system of a wind turbine to minimize loads on the yaw system. Background Art

[0002] Modern wind turbines are commonly used to supply electricity to the power grid. These wind turbines generally consist of a tower and a rotor mounted on the tower. The rotor, typically consisting of a hub and multiple rotor blades, is set to rotate under the influence of the wind. This rotation generates torque, which is typically transmitted to a generator via the rotor shaft, either directly ("direct drive" or "gearless") or through the use of a gearbox. The generator then generates electricity that can be supplied to the power grid.

[0003] The hub can be rotatably coupled to the front of the nacelle. Furthermore, the hub can be connected to the rotor shaft, which can then be rotatably mounted in the nacelle using one or more bearings arranged in a frame inside the nacelle. The nacelle is a housing arranged atop the tower that can contain and protect the gearbox (if present) and the generator (if not placed outside the nacelle), as well as additional components such as the power converter, auxiliary systems, etc., depending on the wind turbine.

[0004] Wind turbines also typically include a yaw system, which is used to orient the wind turbine's rotor in the prevailing wind direction during operation. To interrupt operation, the rotor can be rotated away from the prevailing wind direction. Typically, when the rotor is aligned with the wind, the yaw system maintains its position with the aid of brakes (e.g., electric brakes and / or hydraulic calipers on the yaw motor). These brakes can be activated and deactivated by the wind turbine's control system.

[0005] During operation, wind direction can change. When the rotor is misaligned with respect to the wind, the yaw system rotates the nacelle about the longitudinal axis of the tower to achieve alignment with the wind. Determination that the nacelle and rotor are no longer aligned with the prevailing wind direction can be made based on, for example, a wind vane mounted on the nacelle. However, other methods based on measuring loads and / or oscillations are also known.

[0006] Generally, if the prevailing wind direction deviates from the rotor and nacelle orientation by more than a predefined threshold (e.g., 5°, 7°, or 10° or more) for at least a predetermined time period, the yaw system may be activated. The predetermined time period may be 1 minute, 5 minutes, 10 minutes, or more. For example, an average value over seconds to minutes, such as an average value over 3 seconds, 10 seconds, 1 minute, or 5 minutes, may be determined to calculate the direction of the prevailing wind speed.

[0007] The yaw system typically performs this rotation of the nacelle with the aid of a yaw drive, which comprises a plurality of motors, such as electric or hydraulic motors, with a suitable gearbox for driving a yaw gear (pinion), which meshes with a ring gear or gear ring attached to the nacelle or to the tower. The nacelle can thus be rotated about the longitudinal axis of the tower in or away from the wind. The rotatable connection between the tower and the nacelle is called a yaw bearing. The yaw bearing can be of roller or sliding type.

[0008] With recent developments in providing larger wind turbines, new challenges have arisen, in which some components of the yaw system may be adversely affected. For example, the yaw gear / pinion, yaw gearbox, yaw bearings, motor shaft, etc. may be more susceptible to damage due to the increased loads associated with larger rotor blades, larger hubs, larger nacelles, etc. Such damage may lead to premature repair and / or replacement of such components. Summary of the Invention

[0009] Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

[0010] In one aspect, the present disclosure is directed to a method for protecting one or more components of a yaw system of a wind turbine. The method includes monitoring one or more load signals indicative of a yaw moment of a rotor of the wind turbine. Furthermore, the method includes evaluating the one or more load signals indicative of the yaw moment of the rotor. The method also includes predicting an optimal activation time for the yaw system based on the evaluated one or more load signals. Furthermore, the method includes activating the yaw system at the optimal activation time to minimize load on the yaw system of the wind turbine.

[0011] In another aspect, the present disclosure is directed to a wind turbine having a tower, a nacelle rotatably mounted atop the tower, a rotor having a plurality of rotor blades, a yaw system, and a controller having a processor configured to perform a plurality of operations. The plurality of operations include, but are not limited to, monitoring one or more load signals indicative of a yawing moment of the rotor, evaluating the one or more load signals indicative of the yawing moment, predicting an optimal activation time for the yaw system based on the evaluated one or more load signals, and activating the yaw system at the optimal activation time to minimize loads on the yaw system of the wind turbine.

[0012] Technical Solution 1. A method for protecting one or more components of a yaw system of a wind turbine, the method comprising:

[0013] monitoring one or more load signals indicative of a yawing moment of a rotor of the wind turbine;

[0014] evaluating the one or more load signals indicative of the yawing moment of the rotor;

[0015] predicting an optimal start-up time for the yaw system based on the evaluated one or more load signals; and

[0016] The yaw system is started at the optimal start time to minimize a load on the yaw system of the wind turbine.

[0017] Technical Solution 2. The method according to Technical Solution 1 further includes monitoring the wind direction at the wind turbine, and starting the yaw system at the optimal start-up time and turning it toward the wind direction.

[0018] Technical Solution 3. The method according to Technical Solution 1 further includes monitoring the one or more load signals indicating the yawing moment of the rotor of the wind turbine via one or more sensors.

[0019] Technical Solution 4. The method according to Technical Solution 1, wherein the one or more load signals indicating the yawing moment of the rotor of the wind turbine include at least one of one or more historical load signals or one or more instantaneous load signals.

[0020] Technical Solution 5. A method according to Technical Solution 4, wherein the historical load signal includes the yaw moment from at least three most recent rotations of the yaw system.

[0021] Technical solution 6. The method according to technical solution 1, wherein evaluating the one or more load signals indicating the yawing moment of the rotor further comprises:

[0022] A sinusoidal waveform is fitted to the one or more load signals.

[0023] Technical Solution 7. The method according to Technical Solution 6, wherein fitting the sinusoidal waveform to the one or more load signals further includes fitting the phase and frequency of the sinusoidal waveform to the one or more load signals.

[0024] Technical solution 8. The method according to technical solution 1, wherein evaluating the one or more load signals indicating the yawing moment of the rotor further comprises:

[0025] A Fast Fourier Transform (FFT) is applied to the one or more load signals.

[0026] Technical Solution 9. The method according to Technical Solution 8, wherein applying the FFT to the one or more load signals further includes converting the one or more load signals into a signal representation in the frequency domain having both phase and frequency.

[0027] Technical Solution 10. The method according to Technical Solution 1, wherein starting the yaw system at the optimal start-up time to minimize the load of the yaw system of the wind turbine further includes implementing a time delay until the one or more load signals are below a predetermined threshold.

[0028] Technical Solution 11. A wind turbine comprising:

[0029] tower;

[0030] a nacelle rotatably mounted on top of the tower;

[0031] a rotor comprising a plurality of rotor blades;

[0032] Yaw system; and

[0033] A controller comprising a processor configured to perform a plurality of operations comprising:

[0034] monitoring one or more load signals indicative of a yawing moment of the rotor;

[0035] evaluating the one or more load signals indicative of the yaw moment;

[0036] predicting an optimal start-up time for the yaw system based on the evaluated one or more load signals; and

[0037] The yaw system is started at the optimal start time to minimize a load on the yaw system of the wind turbine.

[0038] Technical Solution 12. The wind turbine according to Technical Solution 11, wherein the plurality of operations further include monitoring the wind direction at the wind turbine and starting the yaw system and turning it toward the wind direction at the optimal start time.

[0039] Technical Solution 13. The wind turbine according to Technical Solution 11, wherein the plurality of operations further include monitoring the one or more load signals indicative of the yawing moment of the rotor via one or more sensors.

[0040] Technical Solution 14. A wind turbine according to Technical Solution 11, wherein the one or more load signals indicating the yawing moment of the rotor include at least one of one or more historical load signals or one or more instantaneous load signals.

[0041] Technical Solution 15. A wind turbine according to Technical Solution 14, wherein the historical load signal includes the yaw moment from at least three most recent rotations of the yaw system.

[0042] Technical solution 16. The wind turbine according to Technical solution 11, wherein evaluating the one or more load signals indicative of the yawing moment of the rotor further comprises:

[0043] A sinusoidal waveform is fitted to the one or more load signals.

[0044] Technical Solution 17. A wind turbine according to Technical Solution 16, wherein fitting the sinusoidal waveform to the one or more load signals further includes fitting the phase and frequency of the sinusoidal waveform to the one or more load signals.

[0045] Technical solution 18. The wind turbine according to Technical solution 11, wherein evaluating the one or more load signals indicative of the yawing moment of the rotor further comprises:

[0046] A Fast Fourier Transform (FFT) is applied to the one or more load signals.

[0047] Technical Solution 19. The wind turbine according to Technical Solution 18, wherein applying the FFT to the one or more load signals further comprises converting the one or more load signals into a signal representation in the frequency domain having both phase and frequency.

[0048] Technical Solution 20. A wind turbine according to Technical Solution 11, wherein starting the yaw system at the optimal start-up time to minimize the load on the yaw system of the wind turbine further includes implementing a time delay until the one or more load signals are below a predetermined threshold.

[0049] These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims.The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] A complete and enabling disclosure of the invention, including the best mode thereof, to one skilled in the art is set forth in the specification which proceeds with reference to the accompanying drawings in which:

[0051] Figure 1 illustrates a perspective view of an embodiment of a wind turbine according to the present disclosure;

[0052] Figure 2 Graphic Figure 1 A simplified interior view of an embodiment of a nacelle of a wind turbine;

[0053] Figure 3 a block diagram illustrating an embodiment of a controller for a wind turbine according to the present disclosure; and

[0054] Figure 4 A flow chart illustrating an embodiment of a method for protecting one or more components of a yaw system of a wind turbine according to the present disclosure. DETAILED DESCRIPTION

[0055] Reference will now be made in detail to embodiments of the present invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation of the present invention, not limitation of the present invention. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made in the present invention without departing from the scope or spirit of the present invention. For example, a feature illustrated or described as part of an embodiment may be used together with another embodiment to produce yet another embodiment. Therefore, it is intended that the present invention encompasses such modifications and variations as fall within the scope of the appended claims and their equivalents.

[0056] Referring now to the accompanying drawings, Figure 1 A perspective view of an embodiment of a wind turbine 10 according to the present disclosure is illustrated. In an embodiment, as shown, the wind turbine 10 is a horizontal axis wind turbine. Further, as shown, the wind turbine 10 includes a tower 15 extending from a support system 14 on the ground 12, a nacelle 16 mounted on the tower 15, 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 the hub 20 and extending outwardly from the hub 20. In the illustrated embodiment, the rotor 18 has three rotor blades 22. In alternative embodiments, the rotor 18 includes more or less than three rotor blades 22. The tower 15 may be fabricated from tubular steel to define a cavity (not shown) between the support system 14 and the nacelle 16. Figure 1 ). In alternative embodiments, tower 15 is any suitable type of tower having any suitable height. Alternatively, tower 15 may be a hybrid tower including portions made of concrete and portions made of tubular steel. Furthermore, tower 15 may be a partial lattice tower or a full lattice tower.

[0057] Rotor blades 22 are spaced about hub 20 to facilitate rotating rotor 18 to enable kinetic energy from the wind to be converted into usable mechanical energy and subsequently into electrical energy. Rotor blades 22 are mounted to hub 20 by coupling blade root regions 24 to hub 20 at a plurality of load transfer regions 26. Load transfer regions 26 may include hub load transfer regions and blade load transfer regions (neither of which is present in the hub). Figure 1). Loads induced to rotor blades 22 are transferred to hub 20 via load transfer regions 26 .

[0058] In an embodiment, rotor blades 22 may have a length ranging from about 15 meters (m) to about 90 m or more. Rotor blades 22 may have any suitable length that enables wind turbine 10 to function as described herein. For example, non-limiting examples of blade lengths include 20 m or less, 37 m, 48 m, 50 m, 52 m, or a length greater than 91 m. When wind strikes rotor blades 22 from a wind direction 28, rotor 18 rotates about rotor axis 30. As rotor blades 22 rotate and are subjected to centrifugal forces, rotor blades 22 are also subjected to various forces and moments. As such, rotor blades 22 may deflect and / or rotate from a neutral or non-deflected position to a deflected position.

[0059] In addition, the pitch angle of rotor blades 22 (i.e., the angle that determines the orientation of rotor blades 22 relative to wind direction 28) can be varied by pitch system 32 to control the load and power output by wind turbine 10 by adjusting the angular position of at least one rotor blade 22 relative to the wind vector. A pitch axis 34 is shown for each of rotor blades 22. During operation of wind turbine 10, pitch system 32 can specifically vary the pitch angle of rotor blades 22 such that the angle of attack of (portions of) rotor blades 22 is reduced, which facilitates reducing the rotational speed and / or facilitating stalling of rotor 18.

[0060] In an embodiment, the blade pitch of each rotor blade 22 is individually controlled by the turbine controller 36 or by the pitch control system 80 ( Figure 2 ) control. Alternatively, the blade pitch for all rotor blades 22 may be controlled simultaneously by the control system. Furthermore, in an example, when wind direction 28 changes, nacelle 16 may rotate about yaw axis 38 to position rotor blades 22 relative to wind direction 28.

[0061] In an embodiment, the turbine controller 36 is shown as being centralized within the nacelle 16 , however, the turbine controller 36 may be a distributed system throughout the wind turbine 10 , on the support system 14 , within a wind farm, and / or at a remote control center.

[0062] Now refer to Figure 2, illustrates an enlarged cross-sectional view of a portion of the nacelle 16 of the wind turbine 10. More specifically, as shown, the hub 20 of the rotor 18 is rotatably coupled to a generator 42 positioned within the nacelle 16 via a main shaft 44, a gearbox 46, a high-speed shaft 48, and a coupling 50. In an embodiment, the main shaft 44 is arranged at least partially coaxial with a longitudinal axis (not shown) of the nacelle 16. The rotation of the main shaft 44 drives the gearbox 46, which in turn drives the high-speed shaft 48 by converting the relatively slow rotational movement of the rotor 18 and the main shaft 44 into a relatively fast rotational movement of the high-speed shaft 48. The latter is connected to the generator 42 by means of the coupling 50 for generating electrical energy.

[0063] Furthermore, a transformer 90 and / or suitable electronic devices, switches, and / or inverters may be disposed in the nacelle 16 to transform the electrical energy generated by the generator 42, which has a voltage between 400 V and 1000 V, into electrical energy having a medium voltage (e.g., 10-35 kV). The electrical energy is conducted from the nacelle 16 to the tower 15 via power cables.

[0064] The gearbox 46, generator 42, and transformer 90 may be supported by the main support structural frame of the nacelle 16, which may optionally be embodied as a main frame 52. The gearbox 46 may include a gearbox housing connected to the main frame 52 via one or more torque arms 51. Furthermore, as shown, the nacelle 16 also includes a forward main support bearing 60 and an aft main support bearing 62.

[0065] Optionally, main frame 52 is configured to carry all loads caused by the weight of the components of rotor 18 and nacelle 16, as well as wind and rotational loads, and further, to introduce these loads into tower 15 of wind turbine 10. Rotor shaft 44, generator 42, gearbox 46, high-speed shaft 48, coupling 50, and any associated fastening, support, and / or fixing devices (including, but not limited to, main frame 52 and front and rear support bearings 60, 62) are sometimes referred to as drive train 64.

[0066] In some examples, wind turbine 10 may be a direct-drive wind turbine without a gearbox 46. In such an embodiment, generator 42 operates at the same rotational speed as rotor 18. Such a wind turbine also generally has a much larger diameter than a generator used in a wind turbine with a gearbox 46 in order to provide a similar amount of power as a wind turbine with a gearbox.

[0067] Nacelle 16 may also include a yaw system 54 comprising a yaw bearing 31 having two bearing members configured to rotate relative to one another. Tower 15 is coupled to one of the bearing members, and a bedplate or main frame 52 of nacelle 16 is coupled to the other bearing member. Yaw system 54 may further include a yaw drive mechanism 56 that can be used to rotate nacelle 16, and thereby rotor 18, about yaw axis 38 to control the viewing angle of rotor blades 22 relative to wind direction 28.

[0068] The yaw drive mechanism 56 may include a plurality of yaw drives 35 having a motor 33, a gearbox 37, and a pinion 39 for engaging with the yaw bearing 31 for rotating one of the bearing members relative to the other. The yaw bearing 31 may include a plurality of teeth that engage with the teeth of the pinion 39. Figure 2 In the example shown, the yaw drive 35 and the yaw bearing 31 are placed outside the outer diameter of the tower 15 . The teeth of the yaw bearing 31 are oriented outwards, but in other examples, the yaw bearing 31 and the yaw drive 35 may be arranged at the inside of the tower 15 .

[0069] In some examples, one of yaw drives 35 may be a “master” drive, and the other drives may be “auxiliary” drives that follow the instructions of the master drive or adapt their operation to suit the master drive.

[0070] The turbine controller 36 may be communicatively coupled to the yaw drive mechanism 56 of the wind turbine 10 for controlling and / or changing the yaw direction of the nacelle 16 relative to the wind direction 28. As the wind direction 28 changes, the turbine controller 36 may be configured to control the yaw angle of the nacelle 16 about the yaw axis 38 to position the rotor blades 22, and therefore the rotor 18, relative to the wind direction 28, thereby controlling the loads acting on the wind turbine 10. For example, the turbine controller 36 may be configured to transmit control signals or commands to the yaw drive mechanism 56 of the wind turbine 10 via a yaw controller or direct transmission so that the nacelle 16 may rotate about the yaw axis 38 via the yaw bearing 31.

[0071] Still refer to Figure 2 To properly position the nacelle 16 relative to the wind direction 28, the nacelle 16 may also include at least one meteorological measurement system 58, which may include a wind vane and anemometer. The meteorological measurement system 58 may provide information to the turbine controller 36, which may include wind direction 28 and / or wind speed.

[0072] Furthermore, in an embodiment, pitch system 32 may be arranged at least partially as a pitch assembly 66 in hub 20. Pitch assembly 66 includes one or more pitch drive systems 68 and at least one sensor 70. Each pitch drive system 68 is coupled to a corresponding rotor blade 22 (at Figure 1 ), for adjusting the pitch angle of rotor blades 22 along pitch axis 34. Figure 2 Only one of three pitch drive systems 68 is shown.

[0073] In an embodiment, pitch assembly 66 includes at least one pitch bearing 72 coupled to hub 20 and to a corresponding rotor blade 22 (at Figure 1 34 , for rotating the corresponding rotor blade 22 about the pitch axis 34. Pitch drive system 68 includes a pitch drive motor 74, a pitch drive gearbox 76, and a pitch drive pinion 78. Pitch drive motor 74 is coupled to pitch drive gearbox 76 such that pitch drive motor 74 applies mechanical force to pitch drive gearbox 76. Pitch drive gearbox 76 is coupled to pitch drive pinion 78 such that pitch drive pinion 78 is rotated by pitch drive gearbox 76. Pitch bearing 72 is coupled to pitch drive pinion 78 such that rotation of pitch drive pinion 78 causes rotation of pitch bearing 72.

[0074] Pitch drive system 68 is coupled to turbine controller 36 for adjusting the pitch angle of rotor blades 22 upon receiving one or more signals from turbine controller 36. In an embodiment, pitch drive motor 74 is any suitable motor driven by electrical power and / or a hydraulic system that enables pitch assembly 66 to function as described herein. Alternatively, pitch assembly 66 may include any suitable structure, configuration, arrangement, and / or components, such as, but not limited to, a hydraulic cylinder, a spring, and / or a servo mechanism. In certain embodiments, pitch drive motor 74 is driven by energy extracted from the rotational inertia of hub 20 and / or a stored energy source (not shown) that supplies energy to components of wind turbine 10.

[0075] Pitch assembly 66 may also include one or more pitch control systems 80 for controlling pitch drive system 68 according to control signals from turbine controller 36 in the event of specific priority conditions and / or during rotor overspeed. In an embodiment, pitch control system 80 is communicatively coupled to pitch drive system 68 for controlling pitch drive system 68 independently of turbine controller 36. In an embodiment, pitch control system 80 is coupled to pitch drive system 68 and to sensor 70. During normal operation of wind turbine 10, turbine controller 36 may control pitch drive system 68 to adjust the pitch angle of rotor blades 22.

[0076] Now refer to Figure 3 , illustrates a block diagram of an embodiment of a turbine controller 36 according to the present disclosure. As shown, the turbine controller 36 may include one or more processors 82 and associated memory devices 84 configured to perform various computer-implemented functions (e.g., execute the methods, steps, calculations, etc. disclosed herein and store related data). In addition, the turbine controller 36 may also include a communication module 86 to facilitate communication between the turbine controller 36 and various components of the wind turbine 10 (e.g., Figure 2 The communication module 86 may include a sensor interface 88 (e.g., one or more analog-to-digital converters) to allow signals transmitted from one or more sensors 92, 94 to be converted into signals that can be understood and processed by the processor 82. It should be appreciated that the various sensors (e.g., sensors 92, 94) may be communicatively coupled to the communication module 86 using any suitable means. For example, Figure 3 , the sensors 92, 94 can be coupled to the sensor interface 88 via a wired connection. However, in other embodiments, the sensors 92, 94 can be coupled to the sensor interface 88 via a wireless connection, such as by using any suitable wireless communication protocol known in the art. As such, the processor 82 can be configured to receive one or more signals from the sensors 92, 94.

[0077] As used herein, the term "processor" refers not only to what is known in the art as an integrated circuit included in a computer, but also to controllers, microcontrollers, microcomputers, programmable logic controllers (PLCs), application-specific integrated circuits, and other programmable circuits. The processor 82 is also configured to compute advanced control algorithms and communicate with various Ethernet- or serial-based protocols (Modbus, OPC, CAN, etc.). Additionally, the memory device(s) 84 may generally include memory elements 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 disk-read only memory (CD-ROM), magneto-optical disks (MODs), digital versatile disks (DVDs), and / or other suitable memory elements. Such memory device(s) 84 may generally be configured to store suitable computer-readable instructions that, when executed by the processor(s) 82, configure the turbine controller 36 to perform the various functions described herein.

[0078] Now refer to Figure 4 , illustrates a flow chart of an embodiment of a method 100 for protecting one or more components of a yaw system of a wind turbine, such as the yaw system 54 of the wind turbine 10, by reducing the peak power required for yaw according to the present disclosure. Figure 1-3The method 100 is described with reference to the wind turbine 10 and turbine controller 36 described herein. However, it should be recognized by one of ordinary skill in the art that the disclosed method 100 may generally be used to operate any other wind turbine having any suitable configuration. Figure 4 For the purposes of illustration and discussion, the steps are depicted as being performed in a particular order, but the methods discussed herein are not limited to any particular order or arrangement. Those skilled in the art, using the disclosure provided herein, will recognize that the various steps of the methods disclosed herein may be omitted, rearranged, combined, and / or adapted in various ways without departing from the scope of the disclosure.

[0079] As shown at (102), the method 100 includes monitoring one or more load signals indicative of a yaw moment (e.g., a Q moment) of the rotor 18 of the wind turbine 10. For example, in an embodiment, the yaw moment may be monitored via one or more sensors (such as sensors 92, 94). In a particular embodiment, the sensors 92, 94 may be part of an asymmetric load control (ALC) sensor system of the wind turbine 10. Furthermore, in an embodiment, the load signal(s) indicative of the yaw moment may include one or more historical load signals and / or one or more instantaneous load signals (e.g., a D moment and / or a Q moment). For example, in an embodiment, the historical load signal may include the yaw moment from the three most recent rotations of the yaw system 54. In another embodiment, the historical load signal may include the yaw moment from less than three of the most recent rotations or more than three of the most recent rotations of the yaw system 54.

[0080] Still refer to Figure 4 As shown at (104), the method 100 includes evaluating load signal(s) indicative of the yawing moment of the rotor 18. For example, in an embodiment, evaluating the load signal(s) indicative of the yawing moment may include fitting a sinusoidal waveform to the load signal(s). In such an embodiment, fitting the sinusoidal waveform to the load signal(s) includes fitting a phase and a frequency of the sinusoidal waveform to the load signal(s). In another embodiment, evaluating the load signal(s) indicative of the yawing moment includes applying a fast Fourier transform (FFT) to the load signal(s). In such an embodiment, applying the FFT to the load signal(s) includes converting the load signal(s) into a signal representation in the frequency domain having both a phase and a frequency.

[0081] As shown at (106), the method 100 includes predicting an optimal start-up time for the yaw system 54 based on the evaluated load signal(s). As used herein, the optimal start-up time generally refers to the start-up time with the lowest load resistance. Therefore, in an embodiment, starting the yaw system 54 at the optimal start-up time to minimize the load on the yaw system 54 may include implementing a time delay until the load signal(s) are below a predetermined threshold. As shown at (108), the method 100 includes starting the yaw system 54 at the optimal start-up time to minimize the load on the yaw system 54 of the wind turbine 10.

[0082] In another embodiment, method 100 may further include monitoring wind direction 28 at wind turbine 10 , for example, using and activating meteorological measurement system 58 , and activating yaw system 54 and steering it toward wind direction 28 at an optimal activation time.

[0083] Therefore, the present disclosure is directed to an algorithm that combines a yaw request with active transient load reduction and observes previous wind speed / load performance to derive an optimal activation time for the yaw system 54 .

[0084] Further aspects of the invention are provided by the subject matter of the following clauses:

[0085] A method for protecting one or more components of a yaw system of a wind turbine, the method comprising: monitoring one or more load signals indicative of a yaw moment of a rotor of the wind turbine; evaluating the one or more load signals indicative of the yaw moment of the rotor; predicting an optimal activation time for the yaw system based on the evaluated one or more load signals; and activating the yaw system at the optimal activation time to minimize loads on the yaw system of the wind turbine.

[0086] A method according to any preceding clause, further comprising monitoring the wind direction at the wind turbine and activating the yaw system and steering it into the wind direction at an optimal activation time.

[0087] The method according to any preceding clause, further comprising monitoring, via one or more sensors, one or more load signals indicative of a yawing moment of a rotor of the wind turbine.

[0088] The method according to any preceding clause, wherein the one or more load signals indicative of a yawing moment of a rotor of the wind turbine comprise at least one of one or more historical load signals or one or more instantaneous load signals.

[0089] A method according to any preceding clause, wherein the historical load signal comprises yaw moments from at least three recent rotations of the yaw system.

[0090] A method according to any preceding clause, wherein evaluating one or more load signals indicative of the yawing moment of the rotor further comprises fitting a sinusoidal waveform to the one or more load signals.

[0091] A method according to any preceding clause, wherein fitting a sinusoidal waveform to the one or more load signals further comprises fitting a phase and a frequency of the sinusoidal waveform to the one or more load signals.

[0092] A method according to any preceding clause, wherein evaluating one or more load signals indicative of a yawing moment of the rotor further comprises:

[0093] A fast Fourier transform (FFT) is applied to the one or more payload signals.

[0094] A method according to any preceding clause, wherein applying the FFT to the one or more load signals further comprises converting the one or more load signals into a signal representation in the frequency domain having both phase and frequency.

[0095] The method according to any preceding clause, wherein starting the yaw system at an optimal start time to minimize loads on the yaw system of the wind turbine further comprises implementing a time delay until one or more load signals are below a predetermined threshold.

[0096] A wind turbine comprises: a tower; a nacelle rotatably mounted on a top of the tower; a rotor comprising a plurality of rotor blades; a yaw system; and a controller comprising a processor configured to perform a plurality of operations, the plurality of operations comprising: monitoring one or more load signals indicative of a yaw moment of the rotor; evaluating the one or more load signals indicative of the yaw moment; predicting an optimal start-up time for the yaw system based on the evaluated one or more load signals; and starting the yaw system at the optimal start-up time to minimize loads on the yaw system of the wind turbine.

[0097] A wind turbine according to any preceding clause, wherein the plurality of operations further comprises monitoring the wind direction at the wind turbine and activating the yaw system and turning it into the wind direction at an optimal activation time.

[0098] A wind turbine according to any preceding clause, wherein the plurality of operations further comprises monitoring, via one or more sensors, one or more load signals indicative of a yawing moment of the rotor.

[0099] A wind turbine according to any preceding clause, wherein the one or more load signals indicative of the yawing moment of the rotor comprise at least one of one or more historical load signals or one or more instantaneous load signals.

[0100] A wind turbine according to any preceding clause, wherein the historical load signal comprises yaw moments from at least three recent rotations of the yaw system.

[0101] A wind turbine according to any preceding clause, wherein evaluating one or more load signals indicative of a yawing moment of the rotor further comprises:

[0102] Fits a sinusoidal waveform to one or more load signals.

[0103] A wind turbine according to any preceding clause, wherein fitting a sinusoidal waveform to the one or more load signals further comprises fitting a phase and a frequency of the sinusoidal waveform to the one or more load signals.

[0104] A wind turbine according to any preceding clause, wherein evaluating one or more load signals indicative of the yawing moment of the rotor further comprises applying a Fast Fourier Transform (FFT) to the one or more load signals.

[0105] A wind turbine according to any preceding clause, wherein applying the FFT to the one or more load signals further comprises converting the one or more load signals into a signal representation in the frequency domain having both phase and frequency.

[0106] A wind turbine according to any preceding clause, wherein starting the yaw system at an optimal start time to minimize loads on the yaw system of the wind turbine further comprises implementing a time delay until one or more load signals are below a predetermined threshold.

[0107] This written description uses examples to disclose the invention (including the best mode) and also to enable any person skilled in the art to practice the invention (including making and using any devices or systems and performing any incorporated methods). The patentable scope of the invention is defined by the claims and may include other examples that occur to those skilled in the art. If such other examples include structural elements that do not differ from the literal language of the claims, or if such other examples include equivalent structural elements with insubstantial differences from the literal language of the claims, such other examples are intended to be within the scope of the claims.

Claims

1. A method for protecting one or more components of a yaw system of a wind turbine, the method comprising: monitoring one or more load signals indicative of a yawing moment of a rotor of the wind turbine; evaluating the one or more load signals indicative of the yawing moment of the rotor; predicting an optimal activation time for the yaw system based on the evaluated one or more load signals; as well as The yaw system is started at the optimal start time to minimize a load on the yaw system of the wind turbine. 2 . The method of claim 1 , further comprising monitoring the wind direction at the wind turbine and activating the yaw system and turning it toward the wind direction at the optimal activation time. 3 . The method of claim 1 , further comprising monitoring the one or more load signals indicative of the yawing moment of the rotor of the wind turbine via one or more sensors.

4. The method according to claim 1, wherein The one or more load signals indicative of the yawing moment of the rotor of the wind turbine include at least one of one or more historical load signals or one or more instantaneous load signals.

5. The method according to claim 4, wherein The historical load signal includes the yaw moment from at least three most recent rotations of the yaw system.

6. The method according to claim 1, wherein Evaluating the one or more load signals indicative of the yawing moment of the rotor further comprises: A sinusoidal waveform is fitted to the one or more load signals.

7. The method according to claim 6, wherein: Fitting the sinusoidal waveform to the one or more load signals further includes fitting a phase and a frequency of the sinusoidal waveform to the one or more load signals.

8. The method according to claim 1, wherein Evaluating the one or more load signals indicative of the yawing moment of the rotor further comprises: A Fast Fourier Transform (FFT) is applied to the one or more load signals.

9. The method according to claim 8, wherein Applying the FFT to the one or more load signals further includes converting the one or more load signals into a signal representation in the frequency domain having both phase and frequency.

10. The method according to claim 1, wherein Starting the yaw system at the optimal start time to minimize loads on the yaw system of the wind turbine further includes implementing a time delay until the one or more load signals are below a predetermined threshold.

Images