Systems and methods for controlling a wind turbine

Abstract

The present invention relates to systems and methods for controlling a wind turbine. Thus, a controller of the wind turbine detects a loss of traction of a slip coupling between a rotor and a generator of a drivetrain of the wind turbine. In response to detecting the loss of traction, the controller overrides a generator torque setpoint to vary the speed of the generator. In response to the varied speed of the generator, the traction of the slip coupling increases. Increasing the traction of the slip coupling facilitates applying a generator torque to the drivetrain of the wind turbine.

Description

Technical Field

[0001] The present disclosure generally relates to wind turbines, and more particularly to systems and methods for controlling a wind turbine to increase the traction of a slip coupling in a drivetrain. Background Art

[0002] Wind power is considered one of the cleanest and most environmentally friendly energy sources currently available, and in this regard, wind turbines have received increasing attention. Modern wind turbines typically include a tower, a generator, a gearbox, a nacelle, and one or more rotor blades. The nacelle includes a rotor assembly that is coupled to the gearbox and to the generator. The rotor assembly and the gearbox are mounted on a floor support frame located within the nacelle. One or more rotor blades use known airfoil principles to capture the kinetic energy of the wind. The rotor blades transfer the kinetic energy in the form of rotational energy to cause a shaft that couples the rotor blades to the gearbox or directly to the generator in the case where no gearbox is used to rotate. The generator then converts the mechanical energy into electrical energy, and the electrical energy can be transmitted to a converter and / or transformer housed within the tower and subsequently deployed to the public power grid. Modern wind power systems typically take the form of a wind farm having a plurality of such wind turbine generators that are operable to supply power to a transmission system for providing power to the grid.

[0003] In certain instances, it may be desirable to use the generator to apply a braking torque to slow down the rotor. For example, a wind turbine may experience an abnormal operating event such as an overspeed condition, a part of a rotor blade (or the rotor blade as a whole) separating from the wind turbine and / or other significant deviations from the normal operating state of the wind turbine. Such events can cause significant damage to the wind turbine, and thus it is desirable to quickly slow down the rotation of the rotor. However, since the rotor is typically rotatably coupled to the generator via a slip coupling, when it may be desirable to apply generator torque to the drivetrain in other cases, the torque generated by the inertia of the generator and / or the rotor can cause a loss of traction of the slip coupling. Therefore, it may be desirable to control the generator torque to maintain or restore the traction of the slip coupling to facilitate the application of generator torque to the drivetrain.

[0004] Accordingly, the art is constantly seeking new and improved systems and methods to address the aforementioned problems. In this regard, the present disclosure relates to systems and methods for controlling a wind turbine to maintain or increase the traction of a slip coupling. Summary of the Invention

[0005] Aspects and advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned by practice of the invention.

[0006] In one aspect, the present disclosure relates to a method for controlling a wind turbine. The wind turbine may have a drivetrain that includes a rotor rotatably coupled to a generator via a slip coupling. The method may include detecting, using a controller, which may be a controller of the wind turbine, a loss of traction of the slip coupling. In response to detecting the loss of traction, the method may include overriding, using the controller, a generator torque setpoint to vary the speed of the generator. Additionally, the method may include increasing the traction of the slip coupling in response to the varied speed of the generator. Thus, increasing the traction of the slip coupling facilitates applying the generator torque to the drivetrain of the wind turbine.

[0007] In an embodiment, the method may further include receiving, using the controller, an indication of at least one rotational speed from an encoder operably coupled to the generator rotor and / or a high-speed shaft of the drivetrain.

[0008] In an additional embodiment, the controller may be a converter controller. In such an embodiment, the converter controller may have a sampling frequency of at least one sample every 200 microseconds.

[0009] In another embodiment, the rotational speed(s) may be the speed of the generator. Additionally, the method may include detecting, using the controller, the rotational speed at a first sampling interval. The method may further include detecting, using the controller, the rotational speed at a subsequent sampling interval. Moreover, the method may include detecting, using the controller, a change in speed of the generator between the sampling intervals. The change in speed may indicate a deceleration.

[0010] In an embodiment, the method may include determining, using the controller, a deceleration rate of the generator based on the rotational speed detected at the sampling intervals. The deceleration rate may be greater than a rate-of-change threshold for the wind turbine.

[0011] In an additional embodiment, the drivetrain may include a low-speed shaft coupling the rotor to a gearbox. The gearbox may be coupled to the generator via a slip coupling. The method may further include detecting, using the controller, the rotational speed of the low-speed rotor shaft. Moreover, the method may include detecting, using the controller, the rotational speed of the generator. Additionally, the method may include detecting, using the controller, a ratio of the rotational speed of the generator to the rotational speed of the low-speed rotor shaft, which is less than a speed correlation threshold.

[0012] In another embodiment, the (plural) rotational speed(s) may be the rotational speed of the generator. The method may include using a controller to receive an indication of at least one operating parameter of the wind turbine. The at least one (plural) operating parameter(s) may include wind speed, wind direction, and / or the collective pitch angle of the rotor. The method may also include using the controller to determine a correlation between the (plural) operating parameter(s) and the rotational speed of the generator that is below a corresponding correlation threshold.

[0013] In an embodiment, the method may include using a controller to detect a decrease in the inertia encountered by the generator. The inertia encountered by the generator may include at least rotor inertia.

[0014] In a further embodiment, the method may include using a controller to receive indications of the rotational speed of the generator at a first sampling interval and a subsequent sampling interval. The indications may indicate a change in the rotational speed. The method may also include using the controller to determine the air-gap torque of the generator at the sampling interval. Additionally, the method may include using the controller to determine a change in the inertia encountered by the generator based at least in part on the changes in the rotational speed and the air-gap torque at the sampling interval.

[0015] In another embodiment, the method may include using a controller to detect the (plural) operating parameter(s) of the wind turbine. The (plural) operating parameter(s) may include at least one of wind speed, wind direction, or the collective pitch angle of the rotor. Additionally, the method may include using the controller to detect an output parameter of the wind turbine. The output parameter may include at least one of voltage, current, or power. Moreover, the method may include using the controller to detect a correlation between the output parameter and the (plural) operating parameter(s) that is below a correlation threshold.

[0016] In an embodiment, the method may include reducing the torque setpoint of the generator to facilitate an increase in the rotational speed of the generator. Increasing the rotational speed of the generator may facilitate an increase in the traction force of the slip coupling.

[0017] In a further embodiment, the method may include increasing the rotational speed of the generator by driving the generator with a motor.

[0018] In another aspect, the present disclosure relates to a system for controlling a wind turbine. The system may include a generator rotatably coupled to a rotor via a slip coupling and a controller communicatively coupled to the generator. The controller may include at least one processor configured to perform a plurality of operations. The plurality of operations may include any of the operations and / or features described herein.

[0019] These and other features, aspects, and advantages of the present invention will become better 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 invention and, together with the description, serve to explain the principles of the invention.

[0020] Technical solution 1. A method for controlling a wind turbine, the wind turbine having a drivetrain including a rotor rotatably coupled to a generator via a slip coupling, the method comprising:

[0021] Detecting, by a controller, a loss of traction of the slip coupling;

[0022] In response to detecting the loss of traction, overriding, by the controller, a generator torque setpoint to vary the speed of the generator; and

[0023] Increasing the traction of the slip coupling in response to the varied speed of the generator, wherein increasing the traction of the slip coupling facilitates applying a generator torque to the drivetrain of the wind turbine.

[0024] Technical solution 2. The method according to technical solution 1, characterized in that the method further comprises:

[0025] Receiving, by the controller, an indication of at least one rotational speed from an encoder operably coupled to at least one of a generator rotor or a high-speed shaft of the drivetrain.

[0026] Technical solution 3. The method according to technical solution 2, characterized in that the controller is a converter controller, and wherein the converter controller has a sampling frequency of at least one sample every 200 microseconds.

[0027] Technical solution 4. The method according to technical solution 2, characterized in that the at least one rotational speed is the rotational speed of the generator, and wherein detecting the loss of traction of the slip coupling further comprises:

[0028] Detecting, by the controller, the rotational speed at a first sampling interval;

[0029] Detecting, by the controller, the rotational speed at a subsequent second sampling interval; and

[0030] Detecting, by the controller, a change in speed of the generator between the first sampling interval and the second sampling interval, wherein the change in speed includes a deceleration.

[0031] Technical solution 5. The method according to technical solution 4, characterized in that detecting the change in speed of the generator further comprises:

[0032] Using the controller to determine a deceleration rate of the generator based on the rotational speed detected at the sampling interval, wherein the deceleration rate is greater than a change rate threshold for the wind turbine.

[0033] Technical solution 6. The method according to technical solution 2, characterized in that the drive train further includes a low-speed shaft that couples the rotor to a gearbox, the gearbox is coupled to the generator via the slip coupling, and the method further includes:

[0034] Using the controller to detect the rotational speed of the low-speed rotor shaft;

[0035] Using the controller to detect the rotational speed of the generator;

[0036] Using the controller to determine a ratio of the rotational speed of the generator to the rotational speed of the low-speed rotor shaft, which is less than a speed correlation threshold.

[0037] Technical solution 7. The method according to technical solution 2, characterized in that the at least one rotational speed is the rotational speed of the generator, and the method further includes:

[0038] Using the controller to receive an indication of at least one operating parameter of the wind turbine, the at least one operating parameter including at least one of wind speed, wind direction, or the total pitch angle of the rotor; and

[0039] Using the controller to determine a correlation between the at least one operating parameter and the rotational speed of the generator that is below a corresponding correlation threshold.

[0040] Technical solution 8. The method according to technical solution 1, characterized in that detecting a loss of the traction force of the slip coupling further includes:

[0041] Using the controller to detect a decrease in the inertia experienced by the generator, wherein the inertia experienced by the generator at least includes rotor inertia.

[0042] Technical solution 9. The method according to technical solution 8, characterized in that detecting the decrease in the inertia experienced by the generator includes:

[0043] Using the controller to receive an indication of the rotational speed of the generator at a first sampling interval and a subsequent second sampling interval, the indication indicating a change in the rotational speed;

[0044] Using the controller to determine the air gap torque of the generator at the first sampling interval and the second sampling interval;

[0045] Use the controller to determine a change in the inertia experienced by the generator based at least in part on the changes in the rotational speed and the air gap torque at the first sampling interval and the second sampling interval.

[0046] Technical solution 10. The method according to technical solution 1, characterized in that, detecting the loss of the traction force of the slip coupling further comprises:

[0047] Use the controller to detect at least one operating parameter of the wind turbine, the at least one operating parameter including at least one of wind speed, wind direction or the total pitch angle of the rotor;

[0048] Use the controller to detect the output parameters of the wind turbine, the output parameters including at least one of voltage, current or power; and

[0049] Use the controller to determine a correlation below a correlation threshold between the output parameter and the at least one operating parameter.

[0050] Technical solution 11. The method according to technical solution 1, characterized in that, overriding the generator torque setpoint to change the rotational speed of the generator further comprises:

[0051] Reduce the torque setpoint of the generator to facilitate an increase in the rotational speed of the generator, wherein increasing the rotational speed of the generator promotes an increase in the traction force of the slip coupling.

[0052] Technical solution 12. The method according to technical solution 1, characterized in that, increasing the traction force of the slip coupling further comprises:

[0053] Increase the rotational speed of the generator by driving the generator with a motor.

[0054] Technical solution 13. A system for controlling a wind turbine, the system comprising:

[0055] A generator rotatably coupled to a rotor via a slip coupling; and

[0056] A controller communicatively coupled to the generator, the controller including at least one processor configured to perform a plurality of operations, the plurality of operations including:

[0057] Detecting a loss of traction force of the slip coupling,

[0058] In response to detecting a loss of the traction force, override the generator torque setpoint to vary the speed of the generator, and

[0059] increase the traction force of the slip coupling in response to the varied speed of the generator, wherein increasing the traction force of the slip coupling facilitates applying the generator torque to the drivetrain of the wind turbine.

[0060] Aspect 14. The system according to Aspect 13, wherein the plurality of operations further includes:

[0061] Receiving an indication of at least one rotational speed from an encoder operably coupled to at least one of the high-speed shaft or the generator rotor.

[0062] Aspect 15. The system according to Aspect 14, wherein the controller is a converter controller, and wherein the converter controller has a sampling frequency of at least one sample every 200 milliseconds.

[0063] Aspect 16. The system according to Aspect 14, wherein detecting the loss of the traction force of the slip coupling further includes:

[0064] Detecting the rotational speed at a first sampling interval;

[0065] Detecting the rotational speed at a subsequent sampling interval; and

[0066] Detecting a change in speed of the generator between the sampling intervals, wherein the change in speed includes deceleration.

[0067] Aspect 17. The system according to Aspect 15, wherein detecting the change in speed of the generator further includes:

[0068] Using the controller to determine a deceleration rate of the generator based on the rotational speed detected at the sampling intervals, wherein the deceleration rate is greater than a rate-of-change threshold for the wind turbine.

[0069] Aspect 18. The system according to Aspect 15, wherein detecting the loss of the traction force of the slip coupling further includes:

[0070] Detecting a decrease in the inertia experienced by the generator, wherein the inertia experienced by the generator includes at least rotor inertia, and wherein detecting the decrease in the inertia includes:

[0071] Receiving an indication of the rotational speed of the generator at a first sampling interval and a subsequent sampling interval, the indication indicating a change in the rotational speed,

[0072] Determine the air gap torque of the generator at the sampling interval, and

[0073] Determine a change in the inertia experienced by the generator based at least in part on the changes in the speed and the air gap torque at the sampling interval.

[0074] Aspect 19. The system according to Aspect 13, wherein overriding the generator torque setpoint to change the speed of the generator further includes:

[0075] Decrease the torque setpoint of the generator to facilitate an increase in the speed of the generator, wherein increasing the speed of the generator facilitates an increase in the traction force of the slip coupling.

[0076] Aspect 20. The system according to Aspect 13, wherein increasing the traction force of the slip coupling further includes:

[0077] Increase the speed of the generator by driving the generator with a motor. Description of the Drawings

[0078] The present invention (including its best mode) for a person of ordinary skill in the art is set forth in a complete and enabling disclosure in the description with reference to the accompanying drawings, in which:

[0079] Figure 1 Perspective view of an embodiment of a wind turbine according to the present disclosure;

[0080] Figure 2 Perspective interior view of an embodiment of a nacelle of a wind turbine according to the present disclosure;

[0081] Figure 3 Schematic diagram of an embodiment of a drivetrain of a wind turbine according to the present disclosure;

[0082] Figure 4 Schematic diagram of an embodiment of an electrical system for use with a wind turbine according to the present disclosure;

[0083] Figure 5 Block diagram of an embodiment of a controller for use with a wind turbine according to the present disclosure;

[0084] Figure 6 Flowchart of an embodiment of the control logic of a system for controlling a wind turbine according to the present disclosure;

[0085] Figure 7A flowchart of an embodiment of a portion of the control logic corresponding to the detection of the loss of traction force of a sliding coupling according to the present disclosure; Figure 6 ;

[0086] Figure 8 A flowchart of an embodiment of a portion of the control logic corresponding to the detection of the loss of traction force of a sliding coupling according to the present disclosure; Figure 6 ;

[0087] Figure 9 A flowchart of an embodiment of a portion of the control logic corresponding to the detection of the loss of traction force of a sliding coupling according to the present disclosure; Figure 6 ; and

[0088] Figure 10 A flowchart of an embodiment of a portion of the control logic corresponding to the detection of the loss of traction force of a sliding coupling according to the present disclosure; Figure 6 ;

[0089] The repeated use of reference characters in this specification and the drawings is intended to represent the same or similar features or elements of the present invention. Detailed Description of the Invention

[0090] 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 and not limitation thereof. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit thereof. For example, features illustrated or described as part of one embodiment can be used with another embodiment to yield still another embodiment. Accordingly, it is intended that the present invention cover such modifications and variations as come within the scope of the appended claims and their equivalents.

[0091] As used herein, the terms "first", "second", and "third" may be used interchangeably to distinguish one component from another and are not intended to indicate the position or importance of individual components.

[0092] Unless otherwise specified herein, the terms "coupled", "fixed", "attached to", etc. refer to both direct coupling, fixing, or attaching and indirect coupling, fixing, or attaching through one or more intermediate components or features.

[0093] As used throughout the specification and claims herein, approximating language may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, values modified by terms such as "about," "approximately," or "substantially" or by multiple such terms will not be limited to the exact values specified. In at least some instances, the approximating language may correspond to the precision of the instrument used to measure the value or the precision of the method or machine used to construct or manufacture the component and / or system. For example, the approximating language may refer to being within 10% limits.

[0094] Herein and throughout the specification and claims, range limitations are combined and interchanged, and such ranges are identified and include all the subranges contained therein unless the context or language indicates otherwise. For example, all ranges disclosed herein include the endpoints, and the endpoints may be combined independently of each other.

[0095] Generally, the present disclosure relates to systems and methods for controlling a wind turbine to facilitate applying generator torque to the drivetrain of the wind turbine. In particular, the present disclosure includes systems and methods that maintain, restore, and / or increase the traction force of a slip coupling between the generator and the rotor of the wind turbine such that generator torque can be applied to the drivetrain. For example, generator torque can be employed to slow the rotation of the rotor as may be required during an emergency brake of the wind turbine. Accordingly, the interaction of the generator torque with the inertia of the rotor can exceed the traction force of the slip coupling, and the slip coupling can begin to slip as it is designed to do. The slip of the slip coupling can be detected by, for example, a sudden deceleration of the generator, the rotational speed of a low-speed shaft that is not related to the rotational speed of the generator, a sudden drop in the inertia experienced by the generator, a lack of correlation between the generator speed and the operating parameters of the wind turbine, and / or a lack of correlation between the output parameters of the wind turbine and the operating parameters. These conditions can, for example, indicate that the generator may no longer be operably coupled to the rotor of the wind turbine, and thus, any torque generated by the generator cannot affect the rotor. When slip is detected by a controller of the wind turbine, the torque setpoint of the generator can be modified such that the generator speed can be changed, generally increased, to reduce the torque present in the slip coupling. When the generator reaches an appropriate rotational speed, the traction force of the slip coupling can be increased such that the slip of the slip coupling terminates. Once the traction force is re-established, torque from the generator can be transmitted to the drivetrain of the wind turbine again.

[0096] Now referring to the drawings, Figure 1FIG. shows a perspective view of a wind turbine 100 according to an embodiment of the present disclosure. As shown, the wind turbine 100 generally includes a tower 102 extending from a support surface 104, a nacelle 106 mounted on the tower 102, and a rotor 108 coupled to the nacelle 106. The rotor 108 includes a rotatable hub 110 and at least one rotor blade 112 coupled to and extending outwardly from the hub 110. For example, in the illustrated embodiment, the rotor 108 includes three rotor blades 112. However, in alternative embodiments, the rotor 108 may include more or fewer than three rotor blades 112. Each rotor blade 112 may be spaced about the hub 110 to facilitate rotation of the rotor 108 such that kinetic energy can be converted from wind into useful mechanical energy and subsequently into electrical energy. For example, the hub 110 may be rotatably coupled to an electric generator 118 ( Figure 2 ) of an electrical system 150 ( Figure 2 ) positioned within the nacelle 106 to permit generation of electrical energy.

[0097] The wind turbine 100 may also include a controller 200 centralized within the nacelle 106. However, in other embodiments, the controller 200 may be located within any other component of the wind turbine 100 or at a location external to the wind turbine. Moreover, the controller 200 may be communicatively coupled to any number of components of the wind turbine 100 to control the components. Accordingly, the controller 200 may include a computer or other suitable processing unit. Thus, in several embodiments, the controller 200 may include suitable computer-readable instructions that, when implemented, cause the controller 200 to be configured to perform various different functions, such as receiving, transmitting, and / or executing wind turbine control signals.

[0098] Now referring to Figure 2-4 , a simplified internal view of an embodiment of the nacelle 106, a schematic view of an embodiment of the drivetrain 146, and Figure 1The exemplary electrical system 150 of the wind turbine 100 shown therein. As shown, the generator 118 may be coupled to the rotor 108 to generate electrical power from the rotational energy generated by the rotor 108. For example, as shown in the illustrated embodiment, the rotor 108 may include a rotor shaft 122 that is coupled to the hub 110 to rotate therewith. The rotor shaft 122 may be rotatably supported by a main bearing 144. The rotor shaft 122 may in turn be rotatably coupled to the high-speed shaft 124 of the generator 118 through an optional gearbox 126 that is connected to the base plate support frame 136 by one or more torque arms 142. As generally understood, the rotor shaft 122 may provide a low-speed high-torque input to the gearbox 126 in response to the rotation of the rotor blades 112 and the hub 110. The gearbox 126 may then be configured with a plurality of gears 148 to convert the low-speed high-torque input into a high-speed low-torque output to drive the high-speed shaft 124 and thus drive the generator 118. In an embodiment, the gearbox 126 may be configured with multiple gear ratios to produce a varying rotational speed of the high-speed shaft for a given low-speed input or vice versa.

[0099] In an embodiment, the rotor 108 may be slowed via the torque generated by the generator 118. Since the generator 118 may generate a torque opposite to the rotation of the rotor 108, the high-speed shaft 124 may be equipped with a slip coupling 154. The slip coupling 154 may prevent damage to the components of the drivetrain 146 due to an overload of the drivetrain 146. Accordingly, the slip coupling 154 may have a traction or release threshold above which the slip coupling 154 may allow the first portion 162 and the second portion 164 of the high-speed shaft 124 to have different rotational speeds. It should be appreciated that if the torque at the slip coupling 154 exceeds the release / traction threshold, the generator 118 may be communicatively disengaged from the rotor 108. In such a case, the torque generated by the generator 118 may not be available to slow the rotor 108, or the increased rotational speed of the rotor 108 may not be available for increased power generation.

[0100] Each rotor blade 112 may also include a pitch control mechanism 120 configured to rotate the rotor blade 112 about its pitch axis 116. Each pitch control mechanism 120 may include a pitch drive motor 128 (e.g., any suitable electric motor, hydraulic motor, or pneumatic motor), a pitch drive gearbox 130, and a pitch drive pinion 132. In such an embodiment, the pitch drive motor 128 may be coupled to the pitch drive gearbox 130 such that the pitch drive motor 128 applies a mechanical force to the pitch drive gearbox 130. Similarly, the pitch drive gearbox 130 may be coupled to the pitch drive pinion 132 to rotate therewith. The pitch drive pinion 132 may in turn be in rotational engagement with a pitch bearing 134 coupled between the hub 110 and the corresponding rotor blade 112 such that rotation of the pitch drive pinion 132 causes rotation of the pitch bearing 134. Thus, in such an embodiment, rotation of the pitch drive motor 128 drives the pitch drive gearbox 130 and the pitch drive pinion 132, thereby rotating the pitch bearing 134 and the rotor blade(s) 112 about the pitch axis 116. Similarly, the wind turbine 100 may include one or more yaw drive mechanisms 138 communicatively coupled to the controller 200, where each yaw drive mechanism 138 is configured to change the angle of the nacelle 106 relative to the wind (e.g., by engaging a yaw bearing 140 of the wind turbine 100).

[0101] Specifically referring to Figure 2 , in an embodiment, the wind turbine 100 may include an environmental sensor 156 configured to collect data indicative of one or more environmental conditions. The environmental sensor 156 may be operatively coupled to the controller 200. Thus, in an embodiment, the environmental sensor(s) 156 may be, for example, a wind vane, an anemometer, a lidar sensor, a thermometer, a barometer, or any other suitable sensor. Data collected by the environmental sensor(s) 156 may include measurements of wind speed, wind direction, wind shear, gusts, wind direction shifts, atmospheric pressure, and / or temperature. In at least one embodiment, the environmental sensor(s) 156 may be mounted to the nacelle 106 at a location downwind of the rotor 108. In an alternative embodiment, the environmental sensor(s) 156 may be coupled to or integrated with the rotor 108. It should be appreciated that the environmental sensor(s) 156 may include a sensor network and may be located remote from the turbine 100.

[0102] Additionally, the wind turbine 100 may include at least one operating sensor 158. The operating sensor(s) 158 may be configured to detect the performance of the wind turbine 100, for example, in response to environmental conditions. For example, the operating sensor(s) 158 may be a rotational speed sensor operably coupled to the controller 200. The operating sensor(s) 158 may be directed at the rotor shaft 122 of the wind turbine 100 and / or the generator 118. The operating sensor(s) 158 may collect data indicative of the rotational speed and / or rotational position of the rotor shaft 122 and, thus, may collect data indicative of the rotor 108 in the form of rotor speed and / or rotor azimuth angle. In an embodiment, the operating sensor(s) 158 may be an analog tachometer, a DC tachometer, an AC tachometer, a digital tachometer, a contact tachometer, a non-contact tachometer, or a time and frequency tachometer. In an embodiment, the operating sensor(s) 158 may be, for example, an encoder, such as an optical encoder.

[0103] In an embodiment, the operating sensor(s) 158 and / or the environmental sensor(s) 156 may be configured to monitor an operating parameter 348 of the wind turbine 100 ( Figure 9 ). For example, the operating sensor(s) 158 and / or the environmental sensor(s) 156 may monitor at least one of wind speed, wind direction, or the total pitch angle of the rotor 108.

[0104] Moreover, in an embodiment, the wind turbine 100 may include an output sensor 160 configured to monitor at least one output parameter 360 of the electrical system 150 ( Figure 10 ). For example, in monitoring the output parameter(s) 360, the output sensor 160 may monitor voltage, current, and / or power generated and / or consumed by the wind turbine 100. Thus, in an embodiment, the operating sensor(s) 158 may be an ammeter, a voltmeter, an ohmmeter, and / or any other suitable sensor for monitoring the output parameter(s) 360 of the electrical system 150 and, thus, the wind turbine 100.

[0105] It should also be appreciated that, as used herein, the term "monitor" and variations thereof indicate that the various sensors of the wind turbine 100 may be configured to provide either a direct measurement of the parameter being monitored or an indirect measurement of such a parameter. Thus, the sensors described herein may be used, for example, to generate a signal related to the parameter being monitored, which signal may then be utilized by the controller 200 to determine the condition or response of the wind turbine 100.

[0106] Specifically referring to Figure 4, in an embodiment, the electrical system 150 may include various components for converting the kinetic energy of the rotor 108 into an electrical output in a form acceptable to the connected power grid. For example, in an embodiment, the generator 118 may be a doubly-fed induction generator (DFIG) having a stator 117 and a generator rotor 119. The generator 118 may be coupled to the stator bus 166 and the power converter 168 via the rotor bus 170. In such a configuration, the stator bus 166 may provide the output polyphase power (e.g., three-phase power) from the stator of the generator 118, and the rotor bus 170 may provide the output polyphase power (e.g., three-phase power) of the generator rotor 119 of the generator 118. Additionally, the generator 118 may be coupled to the rotor-side converter 172 via the rotor bus 170. The rotor-side converter 172 may be coupled to the line-side converter 174, which in turn may be coupled to the line-side bus 176.

[0107] In an embodiment, the rotor-side converter 172 and the line-side converter 174 may be configured for normal operating modes in a three-phase pulse-width modulation (PWM) arrangement using insulated gate bipolar transistors (IGBTs) as switching devices. Other suitable switching devices may be used, such as insulated gate commutated thyristors, MOSFETs, bipolar transistors, silicon-controlled rectifiers, and / or other suitable switching devices. The rotor-side converter 172 and the line-side converter 174 may be coupled via a DC link 173, and a DC link capacitor 175 may be across the DC link 173.

[0108] In an embodiment, the power converter 168 may be coupled to a controller 200, and the controller 200 is configured as a converter controller 202 for controlling the operation of the power converter 168. For example, the converter controller 202 may send control commands to the rotor-side converter 172 and the line-side converter 174 to control the modulation of the switching elements used in the power converter 168 to establish a desired generator torque set point and / or power output.

[0109] As in Figure 4Further depicted in, in an embodiment, the electrical system 150 may include a transformer 178 that couples the wind turbine 100 to the power grid 179. In an embodiment, the transformer 178 may be a three-winding transformer that includes a high-voltage (e.g., greater than 12 KVAC) primary winding 180. The high-voltage primary winding 180 may be coupled to the power grid 179. The transformer 178 may also include a medium-voltage (e.g., 6 KVAC) secondary winding 182 coupled to the stator bus 166 and a low-voltage (e.g., 575VAC, 690 VAC, etc.) auxiliary winding 184 coupled to the line bus 176. It should be appreciated that the transformer 178 may be a three-winding transformer as depicted, or alternatively may be a two-winding transformer having only the primary winding 180 and the secondary winding 182; may be a four-winding transformer having the primary winding 180, the secondary winding 182, and the auxiliary winding 184 and additional auxiliary windings; or may have any other suitable number of windings.

[0110] In additional embodiments, the electrical system 150 may include an auxiliary power feed 186 coupled to the output of the power converter 168. The auxiliary power feed 186 may serve as a power source for various components of the wind turbine system 100. For example, the auxiliary power feed 186 may power the fan, pump, motor, and other suitable components of the wind turbine system 100.

[0111] In an embodiment, the electrical system 150 may also include various circuit breakers, fuses, contactors, and other devices to control and / or protect the various components of the electrical system 150. For example, in an embodiment, the electrical system 150 may include a grid circuit breaker 188, a stator bus circuit breaker 190, and / or a line bus circuit breaker 192. When the conditions of the electrical system 150 approach the operating thresholds of the electrical system 150, the (multiple) circuit breakers 188, 190, 192 of the electrical system 150 may connect or disconnect the corresponding components of the electrical system 150.

[0112] Now referring to Figure 5-10 , a number of embodiments of a system 300 for controlling a wind turbine 100 in accordance with the present disclosure are presented. As in Figure 5Specifically shown therein is a schematic diagram of an embodiment of suitable components that may be included within system 300. For example, as shown, system 300 may include a controller 200 that is communicatively coupled to one or more operating sensors 158, one or more output sensors 160, and / or one or more environmental sensors 156. Also, as shown, controller 200 includes one or more processors 206 and associated memory devices 208 configured to perform a variety of computer-implemented functions (e.g., perform methods, steps, operations, etc. and store relevant data as disclosed herein). Additionally, controller 200 may further include a communication module 210 to facilitate communication between controller 200 and various components of wind turbine 100. Also, communication module 210 may include a sensor interface 212 (e.g., one or more analog-to-digital converters) to allow signals transmitted from sensors 156, 158 to be converted into signals that can be understood and processed by processor 206. It should be appreciated that sensors 156, 158, 160 may be communicatively coupled to communication module 210 using any suitable means. For example, sensors 156, 158, 160 may be coupled to sensor interface 212 via a wired connection. However, in other embodiments, sensors 156, 158, 160 may be coupled to sensor interface 212 via a wireless connection (such as by using any suitable wireless communication protocol known in the art). Additionally, communication module 210 may also be operatively coupled to an operating state control module 214 configured to change at least one wind turbine operating state.

[0113] As used herein, the term "processor" refers not only to integrated circuits referred to in the art as being included in a computer, but also to controllers, microcontrollers, microcomputers, programmable logic controllers (PLCs), application specific integrated circuits, and other programmable circuits. Additionally, memory devices 208 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 disc-read only memory (CD-ROM), magneto-optical discs (MOD), digital versatile discs (DVD), and / or other suitable memory elements. Such memory devices 208 may generally be configured to store suitable computer-readable instructions that, when implemented by processors 206, configure controller 200 to perform various functions, including but not limited to detecting anonymized operating events for wind turbine 100 as described herein and initiating an enhanced braking mode and various other suitable computer-implemented functions.

[0114] Specifically referring to Figure 6, as shown at 302, the controller 200 may be configured to detect a loss of traction of the slip coupling 154. In response to detecting a loss of traction of the slip coupling 154, the controller 200 may override the generator torque setpoint of the generator 118 at 304. As depicted at 306, overriding the generator torque setpoint may change the speed of the generator 118. Changing the speed of the generator 118 may increase the traction of the slip coupling 154 at 308. It should be appreciated that increasing the traction of the slip coupling 154 may facilitate applying generator torque to the drivetrain 146 of the wind turbine 100 at 310. It should be further appreciated that changing the generator torque setpoint may include changes to rotor voltage, the angle between the rotor and stator, the feed voltage vector, and / or slip in order to effect the torque of the generator.

[0115] For example, in an embodiment, the controller 200 may be configured to monitor the torque level of the slip coupling 154. It should be appreciated that in embodiments where the torque level of the slip coupling 154 exceeds the nominal release threshold of the slip coupling 154, the slip coupling 154 may operably disengage the generator 118 from the rotor shaft 122. In such an embodiment, then, the torque generated by the generator 118 may not be available to assist in slowing the rotor 108, or the speed of the rotor 108 may not be available to generate power. Accordingly, when the torque level of the slip coupling 154 approaches / exceeds the release threshold, the system 300 may change the speed of the generator 118 in order to maintain or re - establish an operable connection between the generator 118 and the rotor 108.

[0116] In an embodiment, the controller 200 may be configured as a converter controller 202. The converter controller 202 may have data with higher fidelity performance related to the electrical system 150 and may be available to other controllers, such as a turbine controller or a field controller. For example, in an embodiment, the converter controller 202 may have a sampling frequency that is at least one order of magnitude greater than the sampling frequency of the controller 200 configured as a turbine controller. For example, in an embodiment, the converter controller 202 may have a sampling frequency of at least one sample every 200 microseconds. In other words, the converter controller 202 may receive data related to the electrical system 150 at least once every 200 microseconds. The converter controller 202 may also generate command signals to change the state of the components of the electrical system 150 at the same frequency of at least once every 200 microseconds. Therefore, the converter controller 202 may have a greater ability than other controllers 200 to detect the slip of the slip coupling 154 and react to the slip of the slip coupling 154 based on data related to the electrical system 150 (e.g., the rotational speed of the generator, the air gap torque, etc.). It should be appreciated that the slip of the slip coupling 154 due to the loss of traction may cause the generator 118 to be operatively disengaged from the remainder of the drivetrain 146 of the wind turbine 100. Since the generator torque may be particularly critical for slowing down the rotor 108 during abnormal operating events, such as overspeed conditions, a rapid detection of the loss of traction of the slip coupling 154 may be desirable.

[0117] Now referring to Figure 7 , a flowchart of an embodiment of a portion of the control logic of the system 300 corresponding to the detection of the loss of traction at 302 is depicted. In an embodiment, as shown, the controller 200 may receive speed data 312 indicating at least one rotational speed from an encoder operatively coupled to the generator rotor 119 and / or the high-speed shaft 124 of the drivetrain 146.

[0118] In an embodiment, the speed data 312 may indicate the rotational speed of the generator 118. Thus, in an embodiment, the controller 200 may be configured at 314 to detect the rotational speed at a first sampling interval. Moreover, the controller 200 may be configured at 316 to detect the rotational speed at a subsequent second sampling interval. In an embodiment, as shown at 318, the controller 200 of the system 300 may be configured to detect a change in speed of the generator 118 between sampling intervals. In an embodiment, the change in speed may be a deceleration. This deceleration may be a deceleration of the generator rotor 119 and may indicate a loss of traction of the slip coupling 154.

[0119] In an embodiment, the sampling intervals may be continuous, but in other embodiments, the sampling intervals may be separated by a certain number of intervening sampling intervals. However, it should be appreciated that shortening the time elapsed between sampling intervals (e.g., increasing the frequency of the sampling intervals) may improve the responsiveness of system 300 to the onset of loss of traction of slip coupling 154.

[0120] Still referring Figure 7 , as depicted at 320, controller 200 may determine a deceleration rate of generator 118 based on rotational speeds detected at 314 and 316 at a sampling interval. In an embodiment, the controller may compare the deceleration rate to a rate-of-change threshold 324 at 322. Thus, controller 200 may determine at 326 that the deceleration rate is greater than the threshold, and thus indicate at 328 a loss of traction of slip coupling 154. Stated another way, controller 200 (e.g., converter controller 202) may determine that generator 118 is decelerating at a rate greater than would likely be achievable if generator 118 were still operably coupled to rotor 108.

[0121] It should be appreciated that the inertia of the rotating mass of rotor 108 may require a substantial amount of reverse torque in order to decelerate. Thus, controller 200 may be configured to calculate a maximum deceleration of rotor 108 achievable considering the available torque that may be generated by generator 118. However, if the slip coupling should begin to slip, the inertia of rotor 108 cannot be withstood by generator 118, and thus generator 118 may decelerate without a counter force and thus at a rate greater than the rate that would be achievable when operably coupled to rotor 108.

[0122] Now referring Figure 8, a flowchart depicting an embodiment of a portion of the control logic of system 300 corresponding to the detection of a loss of traction at 302. In the embodiment, the controller 200 may detect the rotational speed of the low-speed rotor shaft 122 at 330 based on the received low-speed shaft data 332. As shown at 336, the controller 200 may also receive generator speed data 334 to detect the rotational speed of the generator 118. Additionally, in the embodiment, the controller 200 may determine a speed ratio that correlates the rotational speed of the generator 118 with the rotational speed of the low-speed rotor shaft 122 at 338. As depicted at 340, the controller 200 may compare the speed ratio with a speed correlation threshold 342. Thus, the controller 200 may determine at 344 that the ratio of the rotational speed of the generator 118 to the rotational speed of the low-speed rotor shaft 122 is less than the correlation threshold, and thus indicate a loss of traction of the slip coupling 154 at 328. In other words, when the generator 118 is operatively coupled to the low-speed rotor shaft 122 via the slip coupling 154, the rotational speed of the generator 118 may be determined by the rotational speed of the low-speed rotor shaft 122 as modified by the gearbox 126. However, when traction is lost in the slip coupling 154, the rotational speed of the generator 118 may be independent of the rotational speed of the low-speed rotor shaft 122 such that the rotational speed of one does not affect the rotational speed of the other.

[0123] Now refer to Figure 9 , a flowchart depicting an embodiment of a portion of the control logic of system 300 corresponding to the detection of a loss of traction at 302. In the embodiment, the controller 200 may receive an indication of at least one operating parameter 348 at 346. The (one or more) operating parameters 348 may include an indication of wind speed, wind direction, and / or the total pitch angle of the rotor 108. The controller 200 may also receive generator speed data 334 to detect the rotational speed of the generator 118 at 336. Additionally, in the embodiment, the controller 200 may determine a correlation between the rotational speed of the generator 118 and the operating parameter 348 at 350. As depicted at 352, the controller 200 may compare the determined correlation with a correlation threshold 354. Thus, the controller 200 may determine at 356 that the correlation is less than the correlation threshold, and thus indicate a loss of traction of the slip coupling 154 at 328. In other words, in the embodiment, when the generator 118 is operatively coupled to the rotor 108 and the wind turbine is operating at the indicated (one or more) operating parameters 348, a certain rotational speed of the generator 118 related to the (one or more) operating parameters 348 may be expected. However, when there is slip in the slip coupling 154, the rotational speed of the generator 118 may not be the rotational speed expected for the detected (one or more) operating parameters 348 and may thus be independent of the (one or more) operating parameters 348.

[0124] Now refer to Figure 10, depicts a flowchart of an embodiment of a portion of the control logic of system 300 corresponding to the detection of a loss of traction at 302. In an embodiment, the controller 200 may receive an indication of the (multiple) operating parameters 348 at 346. The controller 200 may also be configured to detect the output parameters 360 of the wind turbine 100 at 358. The output parameters 360 may include an indication of the voltage, current, and / or power output of the electrical system 150 of the wind turbine 100. As depicted at 362, the controller 200 may determine the correlation between the output parameters 360 and the (multiple) operating parameters 348. As depicted at 364, the controller 200 may compare the determined correlation with a correlation threshold 366. Thus, the controller 200 may determine at 368 that the correlation is less than the correlation threshold, and thus indicate a loss of traction of the slip coupling 154 at 328. In other words, in an embodiment, when the generator 118 is operatively coupled to the rotor 108 and the wind turbine is operating under the indicated (multiple) operating parameters 348, a certain output may be expected from the wind turbine 100. For example, under normal operating conditions, for a given wind speed and direction (e.g., the (multiple) operating parameters 348), the wind turbine 100 may be expected to produce a certain power output (e.g., the output parameters 360) for delivery to the power grid. However, in an embodiment in which the generator 118 is operatively disengaged from the drivetrain 146 due to a loss of traction of the slip coupling 154, the output of voltage, current, and / or power from the wind turbine 100 may be significantly reduced.

[0125] Referring again to Figure 6 , in an embodiment, the detection of a loss of traction at 300 may include detecting a decrease in the inertia experienced by the generator 118 at 370. The inertia experienced by the generator 118 may include at least the inertia of the rotor 108. However, in an embodiment, the inertia experienced or undergone by the generator 118 may also include the inertia of the engaged portions of the multiple gears 148 and the low-speed rotor shaft 122. In an embodiment in which a generator braking torque is applied to the drivetrain 146 in response to an abnormal operating event, the inertia experienced by the generator 118 may be the rotational force resisted by the generator 118.

[0126] As depicted at 372, in an embodiment, the controller 200 may be configured to detect a decrease in the inertia experienced / resisted by the generator 118 by receiving indications of the rotational speed of the generator 118 at a first sampling interval and a subsequent second sampling interval. Based on the rotational speed indications, the controller may determine, at 374, a change in the rotational speed of the generator 118. In particular, in an embodiment, the indication may correspond to a deceleration of the generator 118 that is caused by the braking torque of the generator 118 and is not impeded by the inertia of the rotor 108 during a braking operation. In addition to the rotational speed indications, the controller 200 may also be configured to determine, at 376, the air gap torque of the generator 118 at the sampling interval. As further depicted at 378, the controller 200 may determine a change in the inertia experienced by the generator 118 using at least the changes in rotational speed and air gap torque at the sampling interval. It should be appreciated that determining the rotational speed of the generator 118 and the calculated air gap torque of the generator 118 may be achieved using only the components of the electrical system 150 and does not require additional sensors and / or communication protocols, such as low-speed rotor shaft 122 speed data 332. Thus, in an embodiment, the converter controller 202 may quickly detect a decrease in the inertia experienced by the generator 118, thereby facilitating a quick response to the loss of traction of the slip coupling 154.

[0127] Still referring to Figure 6 , in an embodiment, as depicted at 380, generator torque setpoint override may include decreasing the torque setpoint of the generator 118. Decreasing the torque setpoint of the generator may facilitate an increase in the rotational speed of the generator 118 by reducing the resistance to the rotation of the generator rotor 119. Thus, as depicted at 382, the system 300 may be configured to vary the rotational speed of the generator by increasing the rotational speed. In at least one embodiment, as depicted at 384, increasing the rotational speed of the generator 118 may include driving the generator with a motor to accelerate the generator rotor 119. It should be appreciated that increasing the rotational speed of the generator may facilitate an increase in the traction of the slip coupling 154 by keeping the difference between the rotational speeds of the first portion 162 and the second portion 164 of the high-speed shaft 124 within an acceptable degree of synchronization.

[0128] In addition, those skilled in the art will recognize the interchangeability of various features from different embodiments. Similarly, those of ordinary skill in the art can mix and match the various method steps and features described, as well as other known equivalents for such methods and features, to construct additional systems and techniques in accordance with the principles of the present disclosure. Of course, it will be understood that not all such objectives or advantages described above may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the systems and techniques described herein can be embodied or practiced in such a manner as to achieve or optimize one advantage or a group of advantages taught herein, but not necessarily achieve other objectives or advantages that may be taught or suggested herein.

[0129] This written description uses examples to disclose the invention (including the best mode), and also enables any person skilled in the art to practice the invention (including making and using any device or system and performing any incorporated method). The patentable scope of the invention is defined by the claims, and may include other examples that occur to those 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.

[0130] Additional aspects of the invention are provided by the subject matter of the following clauses:

[0131] Clause 1. A method for controlling a wind turbine having a drivetrain including a rotor rotatably coupled to a generator via a slip coupling, the method comprising: detecting, using a controller, a loss of traction of the slip coupling; in response to detecting the loss of traction, overriding, using the controller, a generator torque setpoint to vary a speed of the generator; and increasing, in response to the varied speed of the generator, the traction of the slip coupling, wherein increasing the traction of the slip coupling facilitates applying generator torque to the drivetrain of the wind turbine.

[0132] Clause 2. The method of Clause 1, further comprising: receiving, using the controller, an indication of at least one rotational speed from an encoder operably coupled to at least one of the generator rotor or a high speed shaft of the drivetrain.

[0133] Clause 3. The method of any of the preceding clauses, wherein the controller is a converter controller, and wherein the converter controller has a sampling frequency of at least one sample every 200 microseconds.

[0134] Clause 4. A method according to any of the preceding clauses, wherein the at least one rotational speed is the rotational speed of the generator, and wherein detecting a loss of traction of the slip coupling further comprises: detecting the rotational speed by the controller at a first sampling interval; detecting the rotational speed by the controller at a subsequent sampling interval; and detecting, by the controller, a change in speed of the generator between the sampling intervals, wherein the change in speed comprises a deceleration.

[0135] Clause 5. A method according to any of the preceding clauses, wherein detecting a change in speed of the generator further comprises: determining, by the controller, a deceleration rate of the generator based on the rotational speed detected at the sampling intervals, wherein the deceleration rate is greater than a rate-of-change threshold for the wind turbine.

[0136] Clause 6. A method according to any of the preceding clauses, wherein the drivetrain further comprises a low-speed shaft coupling the rotor to the gearbox, the gearbox being coupled to the generator via a slip coupling, the method further comprising: detecting, by the controller, the rotational speed of the low-speed rotor shaft; detecting, by the controller, the rotational speed of the generator; and determining, by the controller, a ratio of the rotational speed of the generator to the rotational speed of the low-speed rotor shaft that is less than a speed-correlation threshold.

[0137] Clause 7. A method according to any of the preceding clauses, wherein the at least one rotational speed is the rotational speed of the generator, the method further comprising: receiving, by the controller, an indication of at least one operating parameter of the wind turbine, the at least one operating parameter including at least one of wind speed, wind direction, or total pitch angle of the rotor; and determining, by the controller, a correlation between the at least one operating parameter and the rotational speed of the generator that is below a corresponding correlation threshold.

[0138] Clause 8. A method according to any of the preceding clauses, wherein detecting a loss of traction of the slip coupling further comprises: detecting, by the controller, a reduction in inertia experienced by the generator, wherein the inertia experienced by the generator includes at least rotor inertia.

[0139] Clause 9. A method according to any of the preceding clauses, wherein detecting a reduction in inertia experienced by the generator comprises: receiving, by the controller, an indication of the rotational speed of the generator at a first sampling interval and at a subsequent sampling interval, the indication indicating a change in rotational speed; determining, by the controller, the air-gap torque of the generator at the sampling intervals; and determining, by the controller, a change in inertia experienced by the generator based at least in part on the change in rotational speed and air-gap torque at the sampling intervals.

[0140] Clause 10. The method of any of the preceding clauses, wherein detecting a loss of traction of the slip coupling further comprises: using a controller to detect at least one operating parameter of the wind turbine, the at least one operating parameter including at least one of wind speed, wind direction, or the total pitch angle of the rotor; using a controller to detect an output parameter of the wind turbine, the output parameter including at least one of voltage, current, or power; and using a controller to determine a correlation between the output parameter and the at least one operating parameter that is below a correlation threshold.

[0141] Clause 11. The method of any of the preceding clauses, wherein overriding the generator torque setpoint to vary the speed of the generator further comprises: reducing the generator torque setpoint to facilitate an increase in the speed of the generator, wherein increasing the speed of the generator facilitates an increase in the traction of the slip coupling.

[0142] Clause 12. The method of any of the preceding clauses, wherein increasing the traction of the slip coupling further comprises: increasing the speed of the generator by driving the generator with a motor.

[0143] Clause 13. A system for controlling a wind turbine, the system comprising: a generator rotatably coupled to a rotor via a slip coupling; and a controller communicatively coupled to the generator, the controller including at least one processor configured to perform a plurality of operations, the plurality of operations including: detecting a loss of traction of the slip coupling; in response to detecting the loss of traction, overriding the generator torque setpoint to vary the speed of the generator; and increasing the traction of the slip coupling in response to the varied speed of the generator, wherein increasing the traction of the slip coupling facilitates applying the generator torque to the drivetrain of the wind turbine.

[0144] Clause 14. The system of any of the preceding clauses, wherein the plurality of operations further comprises: receiving an indication of at least one rotational speed from an encoder operably coupled to at least one of the high-speed shaft or the generator rotor.

[0145] Clause 15. The system of any of the preceding clauses, wherein the controller is a converter controller, and wherein the converter controller has a sampling frequency of at least one sample every 200 milliseconds.

[0146] Clause 16. The system of any of the preceding clauses, wherein detecting a loss of traction of the slip coupling further comprises: detecting the rotational speed at a first sampling interval; detecting the rotational speed at a subsequent sampling interval; and detecting a change in speed of the generator between the sampling intervals, wherein the change in speed includes a deceleration.

[0147] Clause 17. For a system of any of the preceding clauses, wherein detecting a change in the speed of the generator further comprises: using a controller to determine a deceleration rate of the generator based on a rotational speed detected at a sampling interval, wherein the deceleration rate is greater than a change rate threshold for the wind turbine.

[0148] Clause 18. For a system of any of the preceding clauses, wherein detecting a loss of traction force of the slip coupling further comprises: detecting a decrease in the inertia experienced by the generator, wherein the inertia experienced by the generator includes at least rotor inertia, and wherein detecting the decrease in inertia comprises: receiving indications of the rotational speed of the generator at a first sampling interval and a subsequent sampling interval; the indications indicating a change in rotational speed; determining an air-gap torque of the generator at the sampling interval; and determining a change in the inertia experienced by the generator based at least in part on the changes in rotational speed and air-gap torque at the sampling interval.

[0149] Clause 19. For a system of any of the preceding clauses, wherein overriding the generator torque setpoint to change the speed of the generator further comprises: decreasing the torque setpoint of the generator in order to facilitate an increase in the speed of the generator, wherein increasing the speed of the generator facilitates an increase in the traction force of the slip coupling.

[0150] Clause 20. For a system of any of the preceding clauses, wherein increasing the traction force of the slip coupling further comprises: increasing the speed of the generator by driving the generator with a motor.

Claims

1. A method for controlling a wind turbine having a drivetrain including a rotor rotatably coupled to a generator via a slip coupling, the method comprising: Detecting, using a controller, a loss of traction of the slip coupling; Responsive to detecting the loss of traction, overriding, using the controller, a generator torque setpoint to vary a speed of the generator; And Increasing the traction of the slip coupling in response to the varied speed of the generator, wherein increasing the traction of the slip coupling facilitates applying a generator torque to the drivetrain of the wind turbine.

2. The method according to claim 1, wherein The method further comprises: Receiving, using the controller, an indication of at least one speed from an encoder operatively coupled to at least one of a generator rotor or a high speed shaft of the drivetrain.

3. The method according to claim 2, wherein The controller is a converter controller and wherein the converter controller has a sampling frequency of at least one sample every 200 microseconds.

4. The method according to claim 2, wherein The at least one speed is a speed of the generator and wherein detecting the loss of traction of the slip coupling further comprises: Detecting, using the controller, the speed at a first sampling interval; Detecting, using the controller, the speed at a subsequent second sampling interval; and Detecting, using the controller, a speed change of the generator between the first sampling interval and the second sampling interval, wherein the speed change includes a deceleration.

5. The method according to claim 4, characterized in that, Detecting the speed change of the generator further comprises: Determining, using the controller, a deceleration rate of the generator based on the speeds detected at the first sampling interval and the second sampling interval, wherein the deceleration rate is greater than a rate of change threshold for the wind turbine.

6. The method according to claim 2, wherein The drivetrain further includes a low speed rotor shaft coupling the rotor to a gearbox, the gearbox being coupled to the generator via the slip coupling, the method further comprising: Detecting, using the controller, a speed of the low speed rotor shaft; Detecting, using the controller, a speed of the generator; Determining, using the controller, a ratio of the speed of the generator to the speed of the low speed rotor shaft, which is less than a speed correlation threshold.

7. The method according to claim 2, characterized in that, The at least one speed is a speed of the generator, the method further comprising: Receiving, using the controller, an indication of at least one operating parameter of the wind turbine, the at least one operating parameter including at least one of wind speed, wind direction or total pitch angle of the rotor; and Determining, using the controller, a correlation between the at least one operating parameter and the speed of the generator that is below a corresponding correlation threshold.

8. The method according to claim 1, characterized in that Detecting the loss of traction of the slip coupling further comprises: Detecting, using the controller, a decrease in inertia experienced by the generator, wherein the inertia experienced by the generator includes at least rotor inertia.

9. The method according to claim 8, characterized in that, Detecting the decrease in the inertia experienced by the generator includes: The controller is utilized to receive indications of the rotational speed of the generator at a first sampling interval and a subsequent second sampling interval, the indications indicating a change in the rotational speed; The controller is utilized to determine the air gap torque of the generator at the first sampling interval and the second sampling interval; and The controller is utilized to determine a change in the inertia experienced by the generator based at least in part on changes in the rotational speed and the air gap torque at the first sampling interval and the second sampling interval.

10. The method according to claim 1, characterized in that, Detecting a loss of the traction force of the slip coupling further comprises: The controller is utilized to detect at least one operating parameter of the wind turbine, the at least one operating parameter including at least one of wind speed, wind direction, or the total pitch angle of the rotor; The controller is utilized to detect an output parameter of the wind turbine, the output parameter including at least one of voltage, current, or power; and The controller is utilized to determine a correlation below a correlation threshold between the output parameter and the at least one operating parameter.

11. The method according to claim 1, wherein Overriding the generator torque setpoint to vary the rotational speed of the generator further comprises: Reducing the torque setpoint of the generator so as to facilitate an increase in the rotational speed of the generator, wherein increasing the rotational speed of the generator facilitates an increase in the traction force of the slip coupling.

12. The method according to claim 1, characterized in that, Increasing the traction force of the slip coupling further comprises: Increasing the rotational speed of the generator by driving the generator with a motor.

13. A system for controlling a wind turbine, the system comprising: A generator rotatably coupled to a rotor via a slip coupling; And A controller communicatively coupled to the generator, the controller including at least one processor configured to perform a plurality of operations, the plurality of operations including: Detecting a loss of the traction force of the slip coupling, Responsive to detecting the loss of the traction force, overriding the generator torque setpoint to vary the rotational speed of the generator, and Increasing the traction force of the slip coupling in response to the changed rotational speed of the generator, wherein increasing the traction force of the slip coupling facilitates applying a generator torque to the drivetrain of the wind turbine.

14. The system according to claim 13, wherein The plurality of operations further includes: Receiving an indication of at least one rotational speed from an encoder operably coupled to at least one of a high-speed shaft or a generator rotor.

15. The system according to claim 14, wherein The controller is a converter controller, and wherein the converter controller has a sampling frequency of at least one sample every 200 milliseconds.

16. The system according to claim 14, wherein Detecting a loss of the traction force of the slip coupling further comprises: Detecting the rotational speed at a first sampling interval; Detecting the rotational speed at a subsequent second sampling interval; and Detecting a speed change of the generator between the first sampling interval and the second sampling interval, wherein the speed change includes a deceleration.

17. The system according to claim 16, wherein Detecting the speed change of the generator further comprises: The controller is utilized to determine a deceleration rate of the generator based on the rotational speeds detected at the first sampling interval and the second sampling interval, wherein the deceleration rate is greater than a rate-of-change threshold for the wind turbine.

18. The system according to claim 15, wherein Detecting a loss of the traction force of the slip coupling further includes: Detecting a decrease in the inertia experienced by the generator, wherein the inertia experienced by the generator includes at least rotor inertia, and wherein detecting the decrease in the inertia includes: Receiving indications of the rotational speeds of the generator at a first sampling interval and a subsequent second sampling interval, the indications indicating a change in the rotational speed, Determining the air-gap torque of the generator at the first sampling interval and the second sampling interval, and Determining a change in the inertia experienced by the generator based at least in part on changes in the rotational speed and the air-gap torque at the first sampling interval and the second sampling interval.

19. The system according to claim 13, characterized in that, Override controlling the generator torque setpoint to vary the rotational speed of the generator further includes: Decreasing the torque setpoint of the generator so as to facilitate an increase in the rotational speed of the generator, wherein increasing the rotational speed of the generator facilitates an increase in the traction force of the slip coupling.

20. The system according to claim 13, wherein Increasing the traction force of the slip coupling further includes: Increasing the rotational speed of the generator by driving the generator with a motor.

Images