System and method for controlling a wind turbine

Abstract

The present invention relates to a system and method for controlling a wind turbine. A system and method for controlling wind turbines of a wind farm is provided. Accordingly, a controller determines a performance difference for a wind turbine at a plurality of sampling intervals of a yaw event. The controller determines a trend line for the wind turbine relating the performance difference to a deviation of a wind direction at each of the plurality of sampling intervals from a first yaw angle. A difference between an angle associated with an apex of the trend line and the first yaw angle is utilized by the controller to determine a yaw angle offset. The yaw angle offset is used to adjust a second yaw angle of the wind turbine.

Description

Technical Field

[0001] This disclosure generally relates to wind turbines, and more particularly to systems and methods for controlling wind turbines in a plurality of wind turbines in a wind farm via yaw offset. Background Technology

[0002] Wind power is considered one of the cleanest and most environmentally friendly energy sources available today, and wind turbines have received increasing attention in this regard. A modern wind turbine typically comprises a tower, generator, gearbox, nacelle, and one or more rotor blades. The nacelle contains the rotor assembly, which is coupled to the gearbox and then to the generator. The rotor assembly and gearbox are mounted on a base 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 this kinetic energy as rotational energy, enabling the shaft that is coupled to the gearbox or, without a gearbox, directly to the generator to rotate. The generator then converts the mechanical energy into electrical energy, which can be transmitted to a converter and / or transformer housed within the tower and subsequently deployed to the public power grid. Modern wind power generation systems typically take the form of wind farms with multiple such wind turbine generators, which are operable to supply power to a transmission system that then supplies power to the power grid.

[0003] Capturing the kinetic energy of the wind generally involves yawing the nacelle of the wind turbine into the wind. Typically, when a wind turbine is operating below its rated power, it can produce its maximum power for a given environmental condition when the nacelle and the wind are aligned parallel to each other. Therefore, when the wind and the nacelle are misaligned such that the wind vector intersects the axis of the nacelle, the power output of the wind turbine can be less than the maximum.

[0004] To facilitate maximum power output by wind turbines for given environmental conditions, wind turbines are typically equipped with wind vanes or other sensors that detect wind direction. This information can be used to yaw the nacelle so that it is aligned with the wind. However, this information may lack the desired level of accuracy. For example, the wind vane may be misaligned during installation or after maintenance procedures.

[0005] Additionally, the wind vane is typically mounted downwind of the rotor. Therefore, the interaction between the rotor and the wind can cause a change in wind direction downwind of the rotor. Consequently, the wind vane can be intentionally misaligned, and / or an offset value can be applied to its output. However, misalignment / offset can be calculated based on nominal design and may not reflect variations and / or other factors in the rotor. Thus, the degree of misalignment / offset may not result in the desired level of accuracy.

[0006] In light of the foregoing, there is a growing demand in the art for novel and improved systems and methods for controlling wind turbines in wind farms, which align the nacelle parallel to the wind direction. Summary of the Invention

[0007] Aspects and advantages of the invention will be set forth in part in the description which follows, or will be obvious from the description, or may be learned by practice of the invention.

[0008] In one aspect, this disclosure relates to a method for controlling wind turbines among a plurality of wind turbines in a wind farm. The method may include determining, via a controller, a performance difference for the wind turbine over a plurality of sampling intervals for a yaw event. The performance difference may indicate the ratio of a monitored performance parameter to an estimated performance parameter for the wind turbine. The method may also include determining, via the controller, a trend line for the wind turbine that correlates the performance difference with a deviation of the wind direction from a first yaw angle for the yaw event at each of the plurality of sampling intervals. Additionally, the method may include determining a yaw angle offset via the controller based on the difference between the angle associated with the apex of the trend line and the first yaw angle. Furthermore, the method may include adjusting a second yaw angle of the wind turbine via the controller, at least in part, based on the yaw angle offset.

[0009] In one embodiment, the method may include receiving, via a controller, indications of performance parameters for a specified subset of wind turbines at various sampling intervals across a plurality of sampling intervals. The method may also include, via the controller, modeling expected performance parameters for the wind turbines based on the received indications of performance parameters for the specified subset of wind turbines at various sampling intervals across the plurality of sampling intervals.

[0010] In an additional embodiment, the method may include receiving indications of monitored wind direction from environmental sensors of the wind turbine at various sampling intervals across a plurality of sampling intervals for a yaw event via a controller. The method may also include receiving indications of yaw setpoints from at least a portion of the plurality of wind turbines at least once per yaw event via the controller. The method may further include determining a median yaw setpoint based on the received indications via the controller. The median yaw setpoint may indicate the wind direction of the yaw event. The yaw event wind direction may be the wind direction aligned with the wind turbine axis for the yaw event. Additionally, the method may include determining, via the controller, the difference between the monitored wind direction and a first yaw angle at various sampling intervals across the plurality of sampling intervals. This difference may correspond to the deviation of the wind direction at each sampling interval across the plurality of sampling intervals from the yaw event wind direction. Furthermore, the method may include determining, via the controller, a performance parameter correlation distribution relative to the deviation of the wind direction from the first yaw angle for the yaw event.

[0011] In yet another embodiment, the method may include defining at least a first yaw sector and a second yaw sector. The method may further include determining a first yaw angle offset for the wind turbine when the wind turbine is located in the first yaw sector. Additionally, the method may include determining a second yaw angle offset for the wind turbine when the wind turbine is located in the second yaw sector. The second yaw angle offset is different from the first yaw angle offset.

[0012] In this embodiment, a yaw event may be defined by the period between consecutive yaw setpoint commands received from the controller. A yaw event may include at least five sampling intervals.

[0013] In an additional embodiment, the yaw event may have a duration of 60 seconds. Furthermore, each sampling interval may occur once every 10 seconds within the duration of the yaw event.

[0014] In another embodiment, the method can be repeated for individual yaw events occurring within a sampling period of at least one month.

[0015] In yet another embodiment, adjusting the yaw angle of the wind turbine may include aligning or recalibrating the wind turbine's environmental sensors.

[0016] In this embodiment, the adjustment of the yaw angle of the wind turbine can be completed after the installation and / or maintenance or repair activities of the wind turbine or environmental sensors.

[0017] In another embodiment, the method may include establishing alignment test intervals for the wind turbine. The method may also include determining yaw angle offsets according to a test plan defined by the alignment test intervals to detect drift in the alignment of environmental sensors or the wind turbine.

[0018] In yet another embodiment, the performance parameter may be power output.

[0019] In an embodiment, the performance parameter may be a first performance parameter. The method may further include determining a second performance difference for the wind turbine via a controller at various sampling intervals across a plurality of sampling intervals of the yaw event. The second performance difference may indicate the ratio of a monitored second performance parameter to an estimated second performance parameter for the wind turbine. Additionally, the trend line may be a three-dimensional trend line that correlates the first performance difference and the second performance difference with the deviation of the wind direction from the first yaw angle at various sampling intervals across the plurality of sampling intervals.

[0020] In an additional embodiment, the second performance parameter may include the tip speed ratio, pitch setpoint, yaw moment, wind speed, turbulence intensity, and / or bending moment.

[0021] In another aspect, this disclosure relates to a system for controlling wind turbines in a plurality of wind turbines in a wind farm. The system may include a yaw drive mechanism for yawing the wind turbines and a controller communicatively coupled to the plurality of wind turbines. The controller may include at least one processor configured to perform a plurality of operations. The plurality of operations may include any of the methods, steps, and / or features described herein.

[0022] Technical Solution 1. A method for controlling wind turbines in a wind farm having multiple wind turbines, the method comprising:

[0023] The controller determines the performance difference for the wind turbine at multiple sampling intervals for yaw events, the performance difference indicating the ratio of the monitored performance parameters to the estimated performance parameters for the wind turbine;

[0024] The controller determines a trend line for the wind turbine, the trend line relating the performance difference to the deviation of the wind direction from the first yaw angle for the yaw event in each of the plurality of sampling intervals;

[0025] The controller determines the yaw angle offset based on the difference between the angle associated with the vertex of the trend line and the first yaw angle; and

[0026] The second yaw angle of the wind turbine is adjusted, at least in part, based on the yaw angle offset, via the controller.

[0027] Technical Solution 2. The method according to Technical Solution 1, wherein determining the performance difference for the wind turbine further includes:

[0028] The controller receives, via each of the plurality of sampling intervals, indications of the monitoring performance parameters of each wind turbine for a specified subset of the plurality of wind turbines; and

[0029] The controller models the expected performance parameters for the wind turbines based on the received indications of the monitored performance parameters of each wind turbine in the specified subset at each of the plurality of sampling intervals.

[0030] Technical Solution 3. The method according to Technical Solution 2, wherein determining the trend line for the wind turbine further includes:

[0031] The controller receives indications of monitored wind direction from the environmental sensor of the wind turbine at each of the plurality of sampling intervals during the yaw event;

[0032] The controller receives an indication of the yaw setpoint from at least a portion of the plurality of wind turbines at least once for each yaw event;

[0033] The controller determines a median yaw setpoint based on the received instruction. The median yaw setpoint indicates the wind direction of the yaw event, which is the wind direction that is aerodynamically aligned with the wind turbine and corresponds to the first yaw angle in relation to the yaw event.

[0034] The controller determines the difference between the monitored wind direction and the first yaw angle for each of the plurality of sampling intervals, the difference corresponding to the deviation between the wind direction for each of the plurality of sampling intervals and the wind direction of the yaw event; and

[0035] The controller determines the distribution of the performance difference relative to the deviation between the wind direction and the first yaw angle in response to the yaw event.

[0036] Technical Solution 4. The method according to Technical Solution 3, wherein determining the yaw angle offset further includes:

[0037] At least the first yaw sector and the second yaw sector should be defined;

[0038] When the wind turbine is located in the first yaw sector, a first yaw angle offset is determined for the wind turbine; and

[0039] When the wind turbine is located in the second yaw sector, a second yaw angle offset is determined for the wind turbine, the second yaw angle offset being different from the first yaw angle offset.

[0040] Technical Solution 5. The method according to Technical Solution 1, wherein the yaw event is defined by the period between consecutive yaw setpoint commands received from the controller, and the yaw event includes at least five sampling intervals.

[0041] Technical Solution 6. The method according to Technical Solution 5, wherein the yaw event has a duration of 60 seconds, and wherein each sampling interval occurs once every 10 seconds during the duration of the yaw event.

[0042] Technical Solution 7. The method according to Technical Solution 5, wherein the method is repeated for each yaw event occurring within a sampling period of at least one month.

[0043] Technical Solution 8. The method according to Technical Solution 1, wherein adjusting the second yaw angle of the wind turbine further includes aligning the environmental sensor of the wind turbine with or recalibrating the environmental sensor of the wind turbine.

[0044] Technical Solution 9. The method according to Technical Solution 8, wherein the adjustment of the second yaw angle of the wind turbine is completed after at least one of the installation, maintenance or repair activities of the wind turbine or the environmental sensor.

[0045] Technical Solution 10. The method according to Technical Solution 1 further includes:

[0046] Establish alignment test intervals for the aforementioned wind turbine; and

[0047] The yaw angle offset is determined according to a test plan defined by the alignment test interval in order to detect drift in the alignment of the environmental sensor or the wind turbine.

[0048] Technical Solution 11. The method according to Technical Solution 1, wherein the monitored performance parameters include power output.

[0049] Technical Solution 12. The method according to Technical Solution 1, wherein the performance difference is a first performance difference, and the method further includes:

[0050] The controller determines a second performance difference for the wind turbine at each of the plurality of sampling intervals of the yaw event. The second performance difference indicates the ratio of a monitored second performance parameter to an estimated second performance parameter for the wind turbine. The trend line is a three-dimensional trend line that correlates the first performance difference and the second performance difference with the deviation of the wind direction from the first yaw angle at each of the plurality of sampling intervals.

[0051] Technical Solution 13. The method according to Technical Solution 12, wherein the second estimated performance parameter and the second monitored performance parameter include at least one of the following: tip speed ratio, torque, pitch setpoint, yaw moment, wind speed, turbulence intensity, and bending moment.

[0052] Technical Solution 14. A system for controlling wind turbines in a wind farm, the system comprising:

[0053] Yaw drive mechanism for yawing the wind turbine; and

[0054] A controller communicatively coupled to the yaw drive mechanism, the controller including at least one processor configured to perform a plurality of operations, the plurality of operations including:

[0055] The performance differences for the wind turbine are determined at multiple sampling intervals during yaw events, the performance differences indicating the ratio of monitored performance parameters to estimated performance parameters for the wind turbine.

[0056] A trend line is determined for the wind turbine, the trend line relating the performance difference to the deviation of the wind direction from the first yaw angle for the yaw event at each of the plurality of sampling intervals.

[0057] The yaw angle offset is determined as the difference between the angle associated with the vertex of the trend line and the first yaw angle; and

[0058] The second yaw angle of the wind turbine is adjusted at least in part based on the yaw angle offset.

[0059] Technical Solution 15. The system according to Technical Solution 14, wherein determining the performance difference for the wind turbine further includes:

[0060] Each of the plurality of sampling intervals receives an indication of the monitored performance parameters for a specified subset of the plurality of wind turbines; and

[0061] The received indications, based on the performance parameters of each wind turbine in the specified subset, are used to model the expected performance parameters for the wind turbine in each of the plurality of sampling intervals.

[0062] Technical Solution 16. The system according to Technical Solution 15, wherein determining the trend line for the wind turbine further includes:

[0063] During each of the plurality of sampling intervals of the yaw event, an indication of the monitored wind direction is received from the environmental sensor of the wind turbine;

[0064] Each yaw event receives an indication of the yaw setpoint from at least a portion of the plurality of wind turbines at least once;

[0065] The median yaw setpoint is determined based on the received instruction. The median yaw setpoint indicates the wind direction of the yaw event, which is the wind direction that is aligned with the aerodynamics of the wind turbine for the yaw event and corresponds to the first yaw angle.

[0066] Determine the difference between the monitored wind direction and the first yaw angle for each of the plurality of sampling intervals, the difference corresponding to the deviation between the wind direction of each of the plurality of sampling intervals and the wind direction of the yaw event; and

[0067] For the yaw event, determine the distribution of the performance difference relative to the deviation of the wind direction from the first yaw angle.

[0068] Technical Solution 17. The system according to Technical Solution 16, wherein determining the yaw angle offset further includes:

[0069] At least the first yaw sector and the second yaw sector should be defined;

[0070] When the wind turbine is located in the first yaw sector, a first yaw angle offset is determined for the wind turbine; and

[0071] When the wind turbine is located in the second yaw sector, a second yaw angle offset is determined for the wind turbine, the second yaw angle offset being different from the first yaw angle offset.

[0072] Technical Solution 18. The system according to Technical Solution 14, wherein the yaw event is defined by a period between consecutive yaw setpoint commands received from the controller, the yaw event comprising at least five sampling intervals.

[0073] Technical Solution 19. The system according to Technical Solution 14, wherein adjusting the second yaw angle of the wind turbine further includes aligning the environmental sensor of the wind turbine with or recalibrating the environmental sensor of the wind turbine.

[0074] Technical Solution 20. The system according to Technical Solution 14, wherein the monitored performance parameters include power output.

[0075] These and other features, aspects, and advantages of the invention will become more readily understood with reference to the following description and the appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. Attached Figure Description

[0076] The invention (including its preferred mode) is fully disclosed and can be practiced by one of ordinary skill in the art in the description with reference to the accompanying drawings, in which:

[0077] Figure 1 The figure is a perspective view of one embodiment of a wind turbine according to the present disclosure;

[0078] Figure 2 The figure shows a perspective interior view of one embodiment of the nacelle of a wind turbine according to the present disclosure;

[0079] Figure 3The figure is a schematic diagram of an embodiment of a wind farm with multiple wind turbines according to the present disclosure;

[0080] Figure 4 The figure shows a schematic diagram of one embodiment of a controller according to the present disclosure;

[0081] Figure 5 The figure is a schematic diagram of an embodiment of the control logic of a system for operating a wind turbine according to the present disclosure;

[0082] Figure 6 The illustration is based on this disclosure. Figure 1 A simplified top view of a wind turbine; and

[0083] Figure 7 The illustration is a schematic representation of an embodiment of a trend line for a wind turbine that correlates performance differences with wind direction deviation, according to the present disclosure.

[0084] The repeated use of reference characters in this specification and drawings is intended to indicate the same or similar features or elements of the invention. Detailed Implementation

[0085] Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The various examples are provided by way of explanation rather than limitation of the invention. Indeed, it will be apparent to those skilled in the art that many modifications and variations can be made to the invention without departing from its scope or spirit. For example, a feature partially illustrated or described as one embodiment may be used with another embodiment to produce yet another embodiment. Therefore, it is intended that the invention cover such modifications and variations as fall within the scope of the appended claims and their equivalents.

[0086] Unless otherwise specified herein, the terms “connection,” “fixed,” “attached to,” etc., refer to direct connection, fixation, or attachment, as well as indirect connection, fixation, or attachment via one or more intermediate components or features.

[0087] As used herein throughout the specification and claims, approximate language is appropriate to modify any quantitative expression that may be varied without altering its essential function. Therefore, values ​​modified by one or more terms such as “approximately,” “about,” and “substantially” are not limited to the specified precise value. In at least some instances, approximate 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, approximate language may refer to a margin of 10 percent.

[0088] Throughout the specification and claims, the scope is defined in combination and interchangeably, and unless the context or language otherwise indicates otherwise, such scope is identified and includes all subscopes contained therein. For example, all scopes disclosed herein include endpoints, and endpoints can be combined independently of each other.

[0089] Generally, this disclosure relates to systems and methods for controlling wind turbines, which may be part of a wind farm. In particular, this disclosure may include systems and methods that facilitate the establishment of yaw angle offsets to adjust the yaw angle of the wind turbines. More specifically, this disclosure may include estimating performance parameters for a main wind turbine of a wind farm based on performance parameters of a specified subset of wind turbines at multiple sampling intervals. These estimated performance parameters may be correlated with monitored performance parameters for the main wind turbine. Therefore, a ratio of the monitored performance parameters to the estimated performance parameters can be calculated to determine performance differences.

[0090] Wind turbines in a wind farm can receive yaw setpoint commands during yaw events. These commands orient the turbine's axis parallel to the wind direction. Yaw events can be of a fixed duration, such as 60 seconds, at least in part due to the amount of power consumed during yaw of the turbine's nacelle. Therefore, the wind direction can deviate from its parallel orientation to the turbine's axis during a yaw event and become misaligned with the turbine. However, this deviation from axial alignment can be recorded by the turbine at multiple sampling intervals during the yaw event. For example, each yaw event may include at least five sampling intervals.

[0091] Therefore, the controller can correlate performance differences with deviations in wind direction at various sampling intervals during yaw events. The controller can use this correlation to determine a trend line for the wind turbine. The trend line can reflect changes in the ratio between monitored and estimated performance based on the sensed wind direction. The apex of the trend line indicates the sensed wind direction at which the maximum values ​​of the monitored and estimated performance parameters most closely coincide. If the wind turbine is properly aligned with the wind direction, the apex can occur at the first yaw angle.

[0092] The apex at the first yaw angle can be attributed to the fact that when aligned with the wind at the yaw angle in response to a yaw event, a specified subset of the wind turbine maximizes its corresponding performance parameters, and thus maximizes the estimated performance parameters. Accordingly, the apex of the trend line deviating from the first yaw angle can indicate that the wind turbine is not aligned with the wind. In other words, the apex of the shift can indicate that when the wind turbine's controller senses that the wind turbine is parallel to the wind, the wind turbine can actually be deviated from its aerodynamic alignment with the wind by a number of degrees, which can be the yaw angle at which optimal power is generated. Therefore, when the wind is perceived to be deviating from the reciprocal of the yaw angle, the wind can actually be aligned parallel to the wind turbine's axis. This can result in the wind turbine having performance parameters most closely related to the estimated performance parameters.

[0093] The degree difference between the first yaw angle and the sensed wind angle associated with the vertex represents the yaw angle offset. The yaw angle offset can be used to adjust the yaw angle of a wind turbine. This adjustment can occur, for example, when installing, maintaining, or servicing a wind turbine or environmental sensor. For example, the adjustment may include biasing the sensor measurements of an installed anemometer or wind vane or physically rotating the sensor to achieve the yaw angle offset determined using the systems and methods described herein.

[0094] It should be recognized that using a specified subset of wind turbines to form estimated performance parameters can eliminate the need for measuring wind speed. This reduces the sensor requirements for wind farms and thus reduces costs. For example, using estimated performance parameters instead of wind speed can eliminate the need for weather masts, lidar, or other sensor systems installed within the wind farm.

[0095] It should be further recognized that, compared to directly measuring performance parameters, utilizing performance differences can reduce the number of variables that a control system must consider. For example, calculations based on the power output of a wind turbine can withstand fluctuations in wind speed. This therefore requires monitoring wind speed and makes it more difficult to determine whether power variations over multiple sampling intervals in response to a yaw event are due to deviations in wind direction or wind speed.

[0096] Now refer to the attached diagram, Figure 1The figure shows a perspective view of one embodiment of a wind turbine 100 according to 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 outward 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. The individual rotor blades 112 may be spaced apart around the hub 110 to allow the rotor 108 to rotate so that kinetic energy can be converted from wind into usable mechanical energy and subsequently into electrical energy. For example, the hub 110 may be rotatably coupled to a generator 118 located within the nacelle 106. Figure 2 ), to allow the generation of electrical energy.

[0097] The wind turbine 100 may also include a controller 200 configured as a turbine controller 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. Furthermore, the controller 200 may be communicatively coupled to any number of components of the wind turbine 100 to control those 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, configure the controller 200 to perform a variety of different functions, such as receiving, transmitting, and / or executing wind turbine control signals.

[0098] Now for reference Figure 2 Illustration Figure 1 The diagram shows a simplified internal view of one embodiment of the nacelle 106 of the wind turbine 100. As shown, a generator 118 may be coupled to a 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 coupled to a hub 110 for rotation with the hub 110. The rotor shaft 122 may be rotatably supported by a main bearing 144. The rotor shaft 122 may then be rotatably coupled to a high-speed shaft 124 of the generator 118 via a gearbox 126 connected to a base support frame 136. As generally understood, the rotor shaft 122 may provide a low-speed, high-torque input to the gearbox 126 in response to rotation of the rotor blades 112 and the hub 110. The gearbox 126 may then be configured to convert the low-speed, high-torque input into a high-speed, low-torque output to drive the high-speed shaft 124 and thus the generator 118.

[0099] Each rotor blade 112 may also include a pitch control mechanism 120 configured to rotate each rotor blade 112 about its pitch axis 116. The pitch control mechanism 120 may include a pitch controller 150 configured to receive at least one pitch setpoint command from the controller 200. Furthermore, each pitch control mechanism 120 may include a pitch drive motor 128, 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 imparts mechanical force to the pitch drive gearbox 130. Similarly, the pitch drive gearbox 130 may be coupled to the pitch drive pinion 132 for rotation together with the pitch drive pinion 132. The pitch drive pinion 132 can then be rotatably engaged with the pitch bearing 134 connected 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 causing the pitch bearing 134 and the rotor blade(s) 112 to rotate about the pitch axis 116.

[0100] Similarly, the wind turbine 100 may include one or more yaw drive mechanisms 138 communicatively coupled to the controller 200, wherein each of the plurality of yaw drive mechanisms 138 is configured to change the angle of the nacelle 106 relative to the wind (e.g., by engaging the yaw bearing 140 of the wind turbine 100). It should be appreciated that the controller 200 may guide the yaw of the nacelle 106 and / or the pitch of the rotor blades 112 to aerodynamically orient the wind turbine 100 relative to the wind (W) acting on the wind turbine 100, thereby facilitating power generation.

[0101] Now for reference Figure 3 The illustration shows a schematic diagram of a wind farm 152 according to the present disclosure. As shown, wind farm 152 may include a plurality of wind turbines 100 as described herein and a controller 200 configured as a field controller. For example, as shown in the illustrated embodiment, wind farm 152 may include twelve wind turbines 100. However, in other embodiments, wind farm 152 may include any other number of wind turbines 100, such as fewer than twelve or more than twelve wind turbines 100. In one embodiment, the controller(s) 200 may be communicatively coupled via a wired connection (e.g., by connecting the controllers(s) through a suitable communication link 154 (e.g., a suitable cable). Alternatively, the controllers(s) may be communicatively coupled via a wireless connection (e.g., by using any suitable wireless communication protocol known in the art).

[0102] In several embodiments, wind farm 152 may include a plurality of environmental sensors 156 for monitoring the wind profile of wind (W) that affects wind farm 152 and thus wind turbine 100. Environmental sensors 156 may be configured to acquire data indicating at least one environmental condition. Environmental sensors 156 may be operatively coupled to controller 200. Thus, in embodiments, the plurality of environmental sensors 156 may be, for example, wind vanes, anemometers, lidar sensors, thermometers, barometers, or other suitable sensors. Data acquired by the plurality of environmental sensors 156 may include measurements of wind direction, wind speed, wind shear, gusts, wind direction, atmospheric pressure, pressure gradient, and / or temperature. In at least one embodiment, the plurality of environmental sensors 156 may be mounted to nacelle 106 at a location downwind of rotor 108. It should be appreciated that the plurality of environmental sensors 156 may comprise a network of sensors and may be located remotely from turbine 100. It should be recognized that environmental conditions can vary significantly across the wind farm 152. Therefore, the (multiple) environmental sensors 156 allow local environmental conditions at each wind turbine 100 to be monitored individually by the respective turbine controller and collectively by the farm controller. However, it should be understood that the use of the systems and methods disclosed herein precludes the requirement for the (multiple) environmental sensors 156 to monitor certain environmental conditions, such as wind speed, in order to determine yaw deviation for the wind turbine 100.

[0103] Now for reference Figure 3-7 This presents various aspects of multiple embodiments of a system 300 for controlling a wind turbine 100 according to the present disclosure. For example, in Figure 4 The diagram, specifically shown, illustrates an embodiment of suitable components that may be included within the controller 200. For example, as illustrated, the controller 200 may include one or more processors 206 configured to perform various computer-implemented functions (e.g., performing methods, steps, calculations, etc., as disclosed herein, and storing related data) and associated memory devices(s) 208. Additionally, the controller 200 may include a communication module 210 for facilitating communication between the controller 200 and the wind turbine 100 and its components. Furthermore, the communication module 210 may include a sensor interface 212 (e.g., one or more analog-to-digital converters) for allowing signals transmitted from one or more sensors (such as environmental sensors(s) 156) to be converted into signals that can be understood and processed by the processor 206. It should be appreciated that sensors may be communicatively coupled to the communication module 210 using any suitable means. For example, as shown... Figure 4As shown, the sensor can be connected to the sensor interface 212 via a wired connection. However, in other embodiments, the sensor can be connected to the sensor interface 212 via a wireless connection (e.g., using any suitable wireless communication protocol known in the art). Additionally, the communication module 210 may also be operatively connected to an operation state control module 214 configured to change the operating state of at least one wind turbine.

[0104] As used herein, the term "processor" refers not only to integrated circuits included in a computer as known in the art, but also to controllers, microcontrollers, microcomputers, programmable logic controllers (PLCs), application-specific integrated circuits (ASICs), and other programmable circuits. Additionally, the memory device(s) 208 may generally include memory elements(s), including but not limited to computer-readable media (e.g., random access memory (RAM)), computer-readable non-volatile media (e.g., flash memory), floppy disks, compact disc-read-only memory (CD-ROM), magneto-optical disks (MOD), digital universal discs (DVDs), and / or other suitable memory elements. Such memory device(s) 208 may be generally configured to store suitable computer-readable instructions, which, when implemented by the processor(s) 206, configure the controller 200 to perform a variety of functions, including but not limited to controlling the wind turbines 100 of the plurality of wind turbines 100 in the wind farm 152 as described herein, and a variety of other suitable computer-implemented functions.

[0105] Special reference Figure 5 In one embodiment, the controller 200 of system 300 may be configured to receive monitored performance parameters 302 and estimated performance parameters 304 for wind turbine 100 at multiple sampling intervals 308 during a yaw event 310. The controller 200 may determine a performance difference 306 for wind turbine 100 based on the performance parameters 302 and 304 at the multiple sampling intervals 308. The performance difference 306 may indicate the ratio of monitored performance parameter 302 to estimated performance parameter 304 or the difference between monitored performance parameter 302 and estimated performance parameter 304. For example, the controller 200 may determine at a corresponding sampling interval 308 the percentage of estimated performance parameter 304 actually generated / formed by the wind turbine.

[0106] In embodiments, performance parameters may be performance parameters of the monitored wind turbine 100. For example, in embodiments, performance parameters may include the power output of the wind turbine 100 of wind farm 152. In additional embodiments, performance parameters may be tip speed ratio, pitch setpoint, yaw moment, and / or bending moment. It should be appreciated that utilization of the power output of the wind turbine 100 of wind farm 152 can be particularly advantageous because power output measurement is employed in multiple control schemes involving the control of wind turbine 100 and / or wind farm 152. Therefore, indication of the power output of wind turbine 100 can be reliable and readily available to controller 200.

[0107] In an embodiment, yaw event 310 may be defined by a period between consecutive yaw setpoint commands received from controller 200. For example, yaw setpoint command 312 may be transmitted by controller 200 at set intervals due to power consumption associated with activation of yaw drive mechanism 138. In an embodiment, this interval may have a duration of 60 seconds. Thus, wind turbine 100 may receive yaw setpoint command 312, and nacelle 106 may rotate to be aerodynamically aligned with the wind (W) at a first yaw angle 322 (e.g., aligning the axis (A) of wind turbine 100 parallel to the wind (W)). In such an embodiment, the rotation of nacelle 106 may remain constant at the first yaw angle 322 during yaw event 310 (e.g., 60 seconds) regardless of any deviation of the wind from the aerodynamic alignment.

[0108] In an embodiment, the period between consecutive yaw setpoint commands 312 may include multiple sampling intervals 308. At each sampling interval 308, the controller 200 may receive indications corresponding to the performance of the wind turbine 100 in response to environmental conditions. For example, at each sampling interval 308, the controller 200 may receive monitored performance parameters 302, estimated performance parameters 304, and / or monitored wind direction 314. In an embodiment, each yaw event 310 may include at least five sampling intervals 308. For example, in an embodiment, each sampling interval 308 may occur once every 10 seconds during the duration of the yaw event 310. Therefore, in such an embodiment, the controller 200 may update six times in the middle of a yaw event. Thus, a change in wind direction can be detected, but no reaction is taken to that change. Therefore, the collection of parameters at each sampling interval 308 during the corresponding yaw event 310 can serve as a test sequence for the controller 200 without making deviations from normal wind turbine 100 operation necessary.

[0109] In embodiments, the methods disclosed herein can be repeated for each yaw event 310 occurring within a sampling period 316. The sampling period 316 may have a duration of at least one month (e.g., 30 days). In additional embodiments, the sampling period 316 may be greater than five months (e.g., six months). In embodiments where the sampling period 316 is greater than five months, the system 300 may include more than 500,000 sampling intervals 308 for each wind turbine 100. It should be appreciated that more than 500,000 sampling intervals 308 allow for accurate detection of patterns and / or deviations from patterns that might not be accurately distinguishable with a smaller number of sampling intervals.

[0110] As in Figure 7 As illustrated in the diagram, in this embodiment, controller 200 may determine a trend line 318 for wind turbine 100, which correlates performance difference 306 with wind direction deviation 320 at each of a plurality of sampling intervals 308. Wind direction deviation 320 may be a deviation relative to a first yaw angle 322. The first yaw angle 322 may correspond to a wind direction parallel to the axis (A) of wind turbine 100 for yaw event 310. For example, the first yaw angle 322 may be the angle to which the nacelle yaws in response to yaw setpoint command 312 at the start of yaw event 310. In other words, the reciprocal of the first yaw angle may be the direction of the wind (W) at the start of yaw event 310. It should be appreciated that, in this embodiment, trend line 318 may be determined by controller 200 via multiple expressions.

[0111] Still referencing Figure 7 In one embodiment, the controller 200 may use a trend line 318 to determine a yaw angle offset 324. The yaw angle offset 324 may be the difference between an angle 326 associated with a vertex 328 of the trend line 318 and a first yaw angle 322. In embodiments where the vertex 328 aligns with the first yaw angle 322, such as those depicted by a dashed trend line (TL1), the yaw angle offset 324 may be zero degrees.

[0112] It should be recognized that vertex 328 may correspond to the wind direction in which the correlation between the monitored performance parameter 302 and the estimated performance parameter 304 is greatest. Therefore, vertex 328 may indicate the aerodynamic alignment of nacelle 106 with the wind (W). For example, in an embodiment, vertex 328 may depict the angle of nacelle 106 relative to the wind (W) at which the wind turbine 100 is producing the full estimated performance parameter 304 (e.g., actually producing the estimated amount of power).

[0113] like Figure 5As depicted, in one embodiment, the controller 200 of system 300 may be configured to adjust a second yaw angle 330 of the wind turbine 100 at least in part based on a yaw angle offset 324. The second yaw angle 330 may correspond to the angle to which the nacelle 106 yaws in response to a yaw setpoint command 312 incorporating the yaw angle offset 324. In one embodiment, the adjustment of the second yaw angle 330 may correspond to introducing an offset value into the controller 200. In another embodiment, the adjustment may correspond to the alignment or recalibration of the wind turbine 100's (a plurality of) environmental sensors 156. In one embodiment, the adjustment may be performed after the installation of the wind turbine 100 or the environmental sensors 156. In an additional embodiment, the adjustment may be performed after maintenance or repair activities on the wind turbine 100. For example, the adjustment may include physically rotating a wind direction sensor and / or introducing an offset factor into the control system for the wind turbine 100.

[0114] In an additional embodiment, adjusting the second yaw angle 330 of the wind turbine 100 may include establishing an alignment test interval for the wind turbine 100. The alignment test interval may define a test plan for the wind turbine 100. Thus, the yaw angle offset may be determined according to the test plan in order to detect drift in the alignment of the wind turbine 100 and / or (multiple) environmental sensors 156.

[0115] In one embodiment, the controller 200 may designate a subset 332 of a plurality of wind turbines 100. The controller 200 may then receive indications of performance parameters 334 for each wind turbine of the designated subset 332 at each of a plurality of sampling intervals 308. In at least one embodiment, the controller 200 may select the designated subset 332 of the plurality of wind turbines 100 based on the power output distribution for each of the designated wind turbines 100. For example, in one embodiment, the designated subset 332 may be a plurality of wind turbines 100 having proven similarity in power generation under primary conditions. Alternatively, the designated subset 332 may have an average power generation capability relative to the plurality of wind turbines 100. It should be appreciated that selecting a designated subset 332 having an average or below-average power generation capability under primary conditions ensures that the power generation level from the designated subset 332 can be predictably achieved by the other wind turbines 100 of the wind farm 152.

[0116] In an additional embodiment, the designated subset 332 may include wind turbines 100 located in particularly favorable or unfavorable locations relative to the wind (W) that influence the wind farm 152. For example, the designated subset 332 may include (multiple) wind turbines 100 located at the maximum height point of the wind farm 152 and / or along portions of the perimeter of the wind farm 152 located upwind of other wind turbines 100. Alternatively, the designated subset 332 may be located in unfavorable locations, such as leeward areas or other areas with turbulent airflow. Selecting wind turbines 100 located in unfavorable locations may result in the designated subset 332 having power generation capabilities that can be predictably achieved by other wind turbines 100 located in more favorable locations.

[0117] In an embodiment, the controller 200 may model expected performance parameters 336 for each wind turbine 100 at various sampling intervals 308 of a plurality of sampling intervals 308, based on received indications of performance parameters 334 for each wind turbine 100 of a specified subset 332. The expected performance parameters 336 may correspond to estimated performance parameters 304, and thus may indicate the anticipated / predicted performance parameters for a given wind (W) at a specific sampling interval 308. Additionally, the controller 200 may monitor actual performance parameters for each wind turbine 100 at various sampling intervals 308 of the plurality of sampling intervals 308. It should be appreciated that modeling can be accomplished using techniques known in the art, such as ensemble forecasting.

[0118] Still referencing Figure 5 In an embodiment, to determine trend line 318, controller 200 may receive indications of monitored wind direction 314 from environmental sensor 156 of wind turbine 100 at various sampling intervals 308 of a plurality of sampling intervals 308 during yaw events 310. For example, during a period between yaw setpoint commands 312 (where nacelle 106 may be stationary), environmental sensor 156 may detect wind direction or oscillations relative to a first yaw angle 322. In the case of a period between yaw setpoint commands 312, controller 200 may record these observations without responding to changes in wind direction by commanding yaw actions from yaw drive mechanism 138.

[0119] In an embodiment, the first yaw angle 322 may be determined by the controller 200 without directly measuring the wind direction. Therefore, in an embodiment, the controller 200 may receive indications of the yaw setpoint 312 from at least a portion of the plurality of wind turbines 100 at least once per yaw event 310. For example, in an embodiment, the controller 200 may receive indications of the yaw direction of each wind turbine 100 of the wind farm 152 relative to a fundamental direction (N). In an embodiment, the controller 200 may determine a median yaw setpoint 338 based on the received indications of the yaw setpoint 312. The median yaw setpoint 338 may indicate the wind direction of the yaw event, which may be the wind direction aligned (e.g., aerodynamically aligned) with the axial direction of the wind turbine 100 for the yaw event 310. It should be appreciated that determining the first yaw angle 322 via the median yaw setpoint 338 and without directly measuring the wind direction eliminates errors that could be associated with the alignment / response of any individual wind turbine 100.

[0120] The yaw event wind direction can be considered the dominant wind direction for the yaw event and can remain constant between successive yaw setpoint commands 312. Therefore, any wind direction deviating from the yaw event wind direction can be considered a wind direction deviation 320. Thus, the controller 200 can determine at 340 the difference between the monitored wind direction 314 and the first yaw angle 322 for each of the plurality of sampling intervals 308. This difference can correspond to the deviation 320 of the wind direction for each of the plurality of sampling intervals 308 from the yaw event wind direction / first yaw angle 322. Therefore, in an embodiment, the controller 200 can determine a performance parameter correlation distribution 342 relative to the deviation 320 of the wind direction from the first yaw angle 322 for the yaw event 310. The performance parameter correlation distribution 342 can serve as the basis for determining the trend line 318.

[0121] In an embodiment, the accuracy of the yaw angle offset 324 can be improved by utilizing a second performance parameter in addition to the performance parameters 302 and 304 discussed above. Therefore, in an embodiment, the controller can determine a second performance difference 344 for the wind turbine 100 at each of the plurality of sampling intervals 308. The second performance difference 344 can indicate the ratio of the monitored second performance parameter to the estimated second performance parameter for the wind turbine 100. Including the second performance parameter can transform the trend line 318 into a three-dimensional trend line that correlates the first performance difference 306 and the second performance difference 344 with the deviation 320 of the wind direction from the first yaw angle 322 at each of the plurality of sampling intervals 308. In an embodiment, the second performance parameter may include the tip velocity ratio, pitch setpoint, yaw moment, wind speed, turbulence intensity, and / or bending moment. It should be appreciated that more than two performance parameters can be used to further improve the fidelity of the yaw angle offset 324.

[0122] Special reference Figure 6 As depicted at 346, in an embodiment, system 300 may define at least a first yaw sector 348 and a second yaw sector 350. In an embodiment, an additional yaw sector 350 may be defined as desired. Each of the yaw sectors 348, 350, and 352 may be defined by an arc of rotation of the nacelle 106 relative to the fundamental orientation (N).

[0123] In an embodiment, when the wind turbine 100 is located in the first yaw sector 348, the system 300 can determine / limit a first yaw angle offset 354 for the wind turbine 100. Additionally, when the wind turbine 100 is located in the second yaw sector 350, the system 300 can determine / limit a second yaw angle offset 356 for the wind turbine 100. In an embodiment, the second yaw angle offset 356 may differ from the first yaw angle offset 354. For example, in an embodiment, the second yaw angle offset 356 may be greater than the first yaw angle offset 354. It should be recognized that the layout of the wind farm 152 (e.g., the presence of wake effects from adjacent wind turbines 100) and / or the topography of the wind farm may make it necessary to utilize multiple yaw angle offsets in different yaw sectors. Therefore, utilizing multiple yaw angle offsets allows the system 300 to adjust the second yaw angle 330 taking into account topography, wake effects, and / or other site conditions.

[0124] Furthermore, those skilled in the art will recognize the interchangeability of various features from different embodiments. Similarly, those skilled in the art can mix and match the various method steps and features described, as well as other known equivalents for each such method and feature, to construct additional systems and techniques in accordance with the principles of this disclosure. It will be understood, of course, that not all such objectives or advantages described above may be achieved according to any particular embodiment. Thus, for example, those skilled in the art will recognize that the systems and techniques described herein may be embodied or performed in a manner that achieves or optimizes one or a set of advantages as taught herein, without necessarily achieving other objectives or advantages as may be taught or suggested herein.

[0125] 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 apparatus or system, and performing any incorporated methods). The patentability of the invention is defined by the claims and may include other examples that would occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they comprise structural elements that are not different from the literal language of the claims, or if they comprise equivalent structural elements that are not substantially different from the literal language of the claims.

[0126] Further aspects of the invention are provided by the subject matter of the following provisions:

[0127] Clause 1. A method for controlling wind turbines in a wind farm having multiple wind turbines, the method comprising: determining, via a controller, a performance difference for the wind turbines for multiple sampling intervals of a yaw event, the performance difference indicating the ratio of a monitored performance parameter to an estimated performance parameter for the wind turbines; determining, via the controller, a trend line for the wind turbines that correlates the performance difference with a deviation of the wind direction at each of the multiple sampling intervals from a first yaw angle for the yaw event; determining, via the controller, a yaw angle offset based on the difference between an angle associated with the apex of the trend line and the first yaw angle; and adjusting a second yaw angle of the wind turbines, via the controller, at least in part, based on the yaw angle offset.

[0128] Clause 2. The method according to Clause 1, wherein determining the performance difference for a wind turbine further comprises: receiving, via a controller, at each of a plurality of sampling intervals, indications of monitoring performance parameters of a specified subset of wind turbines for a plurality of wind turbines; and via the controller, modeling, at each of the plurality of sampling intervals, the expected performance parameters for the wind turbines based on the received indications of the monitoring performance parameters of the specified subset of wind turbines.

[0129] Clause 3. The method according to any of the foregoing clauses, wherein determining the trend line for the wind turbine further comprises: receiving, via a controller, an indication of monitored wind direction from an environmental sensor of the wind turbine at each of a plurality of sampling intervals of a yaw event; receiving, via the controller, an indication of a yaw setpoint from at least a portion of the plurality of wind turbines at least once for each yaw event; determining, via the controller, a median yaw setpoint based on the received indications, the median yaw setpoint indicating the yaw event wind direction, the yaw event wind direction being aerodynamically aligned with the wind turbine for the yaw event and corresponding to a first yaw angle; determining, via the controller, a difference between the monitored wind direction and the first yaw angle at each of the plurality of sampling intervals, the difference corresponding to the deviation between the wind direction at each of the plurality of sampling intervals and the yaw event wind direction; and determining, via the controller, a distribution of performance differences relative to the deviation between the wind direction and the first yaw angle for the yaw event.

[0130] Clause 4. The method according to any of the foregoing clauses, wherein determining the yaw angle offset further comprises: defining at least a first yaw sector and a second yaw sector; determining a first yaw angle offset for the wind turbine when the wind turbine is located in the first yaw sector; and determining a second yaw angle offset for the wind turbine when the wind turbine is located in the second yaw sector, the second yaw angle offset being different from the first yaw angle offset.

[0131] Clause 5. The method according to any of the foregoing clauses, wherein the yaw event is defined by a period between consecutive yaw setpoint commands received from the controller, the yaw event comprising at least five sampling intervals.

[0132] Clause 6. The method according to any of the foregoing clauses, wherein the yaw event has a duration of 60 seconds, and wherein each sampling interval occurs once every 10 seconds during the duration of the yaw event.

[0133] Clause 7. The method pursuant to any of the foregoing clauses, wherein the method is repeated for each yaw event occurring within a sampling period of at least one month.

[0134] Clause 8. The method according to any of the foregoing clauses, wherein adjusting the second yaw angle of the wind turbine further includes aligning or recalibrating the environmental sensor of the wind turbine.

[0135] Clause 9. The method according to any of the foregoing clauses, wherein the adjustment of the yaw angle of the wind turbine is completed after at least one of the installation, maintenance or repair activities of the wind turbine or environmental sensor.

[0136] Clause 10. The method pursuant to any of the foregoing clauses further includes: establishing alignment test intervals for wind turbines; and determining yaw angle offsets according to a test plan as defined by the alignment test intervals in order to detect drift in the alignment of the environmental sensors or the wind turbines.

[0137] Clause 11. The method according to any of the foregoing clauses, wherein monitoring performance parameters includes power output.

[0138] Clause 12. The method according to any of the foregoing clauses, wherein the performance difference is a first performance difference, the method further comprising: determining a second performance difference for a wind turbine via a controller at each of a plurality of sampling intervals of a yaw event, the second performance difference indicating the ratio of a monitored second performance parameter for the wind turbine to an estimated second performance parameter, wherein the trend line is a three-dimensional trend line relating the first performance difference and the second performance difference to the deviation of the wind direction from the first yaw angle at each of the plurality of sampling intervals.

[0139] Clause 13. The method according to any of the foregoing clauses, wherein the second performance parameter includes at least one of the following: tip speed ratio, torque, pitch setpoint, yaw moment, wind speed, turbulence intensity, and bending moment.

[0140] Clause 14. A system for controlling a wind turbine in a wind farm, the system comprising: a yaw drive mechanism for yawing the wind turbine; and a controller communicatively coupled to the yaw drive mechanism, the controller including at least one processor configured to perform a plurality of operations, the plurality of operations including: determining a performance difference for the wind turbine at a plurality of sampling intervals of a yaw event, the performance difference indicating a ratio of a monitored performance parameter to an estimated performance parameter for the wind turbine; determining a trend line for the wind turbine that correlates the performance difference with a deviation of the wind direction at each of the plurality of sampling intervals from a first yaw angle for the yaw event; determining a yaw angle offset as the difference between an angle associated with the vertex of the trend line and the first yaw angle; and adjusting a second yaw angle of the wind turbine based at least in part on the yaw angle offset.

[0141] Clause 15. A system pursuant to any of the foregoing clauses, wherein determining performance differences for wind turbines further comprises: receiving, at each of a plurality of sampling intervals, indications of monitoring performance parameters of individual wind turbines for a designated subset of a plurality of wind turbines; and modeling, at each of the plurality of sampling intervals, expected performance parameters for the wind turbines based on the received indications of performance parameters of the individual wind turbines for the designated subset.

[0142] Clause 16. A system according to any of the foregoing clauses, wherein determining a trend line for a wind turbine further comprises: receiving, at each of a plurality of sampling intervals of a yaw event, an indication of monitored wind direction from an environmental sensor of the wind turbine; receiving, at least once for each yaw event, an indication of a yaw setpoint from at least a portion of the plurality of wind turbines; determining, based on the received indication, a median yaw setpoint indicating the yaw event wind direction, the yaw event wind direction being aerodynamically aligned with the wind turbine for the yaw event and corresponding to a first yaw angle; determining, at each of the plurality of sampling intervals, a difference between the monitored wind direction and the first yaw angle, the difference corresponding to the deviation between the wind direction of the respective sampling interval and the yaw event wind direction; and determining, for the yaw event, the distribution of performance differences relative to the deviation between the wind direction and the first yaw angle.

[0143] Clause 17. A system pursuant to any of the foregoing clauses, wherein determining the yaw angle offset further comprises: defining at least a first yaw sector and a second yaw sector; determining a first yaw angle offset for the wind turbine when the wind turbine is located in the first yaw sector; and determining a second yaw angle offset for the wind turbine when the wind turbine is located in the second yaw sector, the second yaw angle offset being different from the first yaw angle offset.

[0144] Clause 18. A system pursuant to any of the foregoing clauses, wherein a yaw event is defined by a period between successive yaw setpoint commands received from the controller, the yaw event comprising at least five sampling intervals.

[0145] Clause 19. In any of the foregoing clauses, adjusting the second yaw angle of the wind turbine further includes aligning or recalibrating the environmental sensor of the wind turbine.

[0146] Clause 20. In any system pursuant to the foregoing clauses, the monitoring of performance parameters includes power output.

Claims

1. A method for controlling wind turbines in a wind farm having multiple wind turbines, the method comprising: The controller determines the performance difference for the wind turbine at multiple sampling intervals for yaw events, the performance difference indicating the ratio of the monitored performance parameters to the estimated performance parameters for the wind turbine; The controller determines a trend line for the wind turbine, the trend line relating the performance difference to the deviation of the wind direction from the first yaw angle for the yaw event in each of the plurality of sampling intervals; The yaw angle offset is determined by the controller based on the difference between the angle associated with the vertex of the trend line and the first yaw angle; as well as The second yaw angle of the wind turbine is adjusted, at least in part, based on the yaw angle offset, via the controller.

2. The method according to claim 1, wherein, Determining the performance differences for the wind turbine further includes: The controller receives, via each of the plurality of sampling intervals, indications of the monitoring performance parameters of each wind turbine for a specified subset of the plurality of wind turbines; and The controller models the expected performance parameters for the wind turbines based on the received indications of the monitored performance parameters of each wind turbine in the specified subset at each of the plurality of sampling intervals.

3. The method according to claim 2, wherein, Determining the trend line for the wind turbine further includes: The controller receives indications of monitored wind direction from the environmental sensor of the wind turbine at each of the plurality of sampling intervals during the yaw event; The controller receives an indication of the yaw setpoint from at least a portion of the plurality of wind turbines at least once for each yaw event; The controller determines a median yaw setpoint based on the received instruction. The median yaw setpoint indicates the wind direction of the yaw event, which is the wind direction that is aerodynamically aligned with the wind turbine and corresponds to the first yaw angle in relation to the yaw event. The controller determines the difference between the monitored wind direction and the first yaw angle for each of the plurality of sampling intervals, the difference corresponding to the deviation between the wind direction for each of the plurality of sampling intervals and the wind direction of the yaw event; and The controller determines the distribution of the performance difference relative to the deviation between the wind direction and the first yaw angle in response to the yaw event.

4. The method according to claim 3, wherein, Determining the yaw angle offset further includes: At least the first yaw sector and the second yaw sector should be defined; When the wind turbine is located in the first yaw sector, a first yaw angle offset is determined for the wind turbine; and When the wind turbine is located in the second yaw sector, a second yaw angle offset is determined for the wind turbine, the second yaw angle offset being different from the first yaw angle offset.

5. The method according to claim 1, wherein, The yaw event is defined by the period between consecutive yaw setpoint commands received from the controller, and the yaw event includes at least five sampling intervals.

6. The method according to claim 5, wherein, The yaw event has a duration of 60 seconds, and each sampling interval occurs once every 10 seconds during the duration of the yaw event.

7. The method according to claim 5, wherein, The method is repeated for each yaw event that occurs within a sampling period of at least one month.

8. The method according to claim 1, wherein, Adjusting the second yaw angle of the wind turbine further includes aligning the environmental sensor of the wind turbine with or recalibrating the environmental sensor of the wind turbine.

9. The method according to claim 8, wherein, The adjustment of the second yaw angle of the wind turbine is completed after at least one of the installation, maintenance, or repair activities of the wind turbine or the environmental sensor.

10. The method of claim 1, further comprising: Establish alignment test intervals for the wind turbine; as well as The yaw angle offset is determined according to a test plan defined by the alignment test interval in order to detect drift in the alignment of the environmental sensor or the wind turbine.

11. The method according to claim 1, wherein, The monitored performance parameters include power output.

12. The method according to claim 1, wherein, The performance difference is a first performance difference, and the method further includes: The controller determines a second performance difference for the wind turbine at each of the plurality of sampling intervals of the yaw event. The second performance difference indicates the ratio of a second monitored performance parameter to a second estimated performance parameter for the wind turbine. The trend line is a three-dimensional trend line that correlates the first performance difference and the second performance difference with the deviation of the wind direction from the first yaw angle at each of the plurality of sampling intervals.

13. The method according to claim 12, wherein, The second estimated performance parameter and the second monitored performance parameter include at least one of the following: tip speed ratio, torque, pitch setpoint, yaw moment, wind speed, turbulence intensity, and bending moment.

14. A system for controlling a wind turbine in a wind farm, the system comprising: A yaw drive mechanism for yawing the wind turbine; as well as A controller communicatively coupled to the yaw drive mechanism, the controller including at least one processor configured to perform a plurality of operations, the plurality of operations including: The performance differences for the wind turbine are determined at multiple sampling intervals during yaw events, the performance differences indicating the ratio of monitored performance parameters to estimated performance parameters for the wind turbine. A trend line is determined for the wind turbine, the trend line relating the performance difference to the deviation of the wind direction from the first yaw angle for the yaw event at each of the plurality of sampling intervals. The yaw angle offset is determined as the difference between the angle associated with the vertex of the trend line and the first yaw angle; as well as The second yaw angle of the wind turbine is adjusted at least in part based on the yaw angle offset.

15. The system according to claim 14, wherein, Determining the performance differences for the wind turbine further includes: Each of the plurality of sampling intervals receives an indication of the monitored performance parameters for a specified subset of the plurality of wind turbines; and The expected performance parameters for the wind turbines are modeled based on the received indications of the performance parameters of each wind turbine in the specified subset at each of the plurality of sampling intervals.

16. The system according to claim 15, wherein, Determining the trend line for the wind turbine further includes: During each of the plurality of sampling intervals of the yaw event, an indication of the monitored wind direction is received from the environmental sensor of the wind turbine; Each yaw event receives an indication of the yaw setpoint from at least a portion of the plurality of wind turbines at least once; The median yaw setpoint is determined based on the received instruction. The median yaw setpoint indicates the wind direction of the yaw event, which is the wind direction that is aligned with the aerodynamics of the wind turbine and corresponds to the first yaw angle in relation to the yaw event. Determine the difference between the monitored wind direction and the first yaw angle for each of the plurality of sampling intervals, the difference corresponding to the deviation between the wind direction of each of the plurality of sampling intervals and the wind direction of the yaw event; and For the yaw event, determine the distribution of the performance difference relative to the deviation of the wind direction from the first yaw angle.

17. The system according to claim 16, wherein, Determining the yaw angle offset further includes: At least the first yaw sector and the second yaw sector should be defined; When the wind turbine is located in the first yaw sector, a first yaw angle offset is determined for the wind turbine; and When the wind turbine is located in the second yaw sector, a second yaw angle offset is determined for the wind turbine, the second yaw angle offset being different from the first yaw angle offset.

18. The system according to claim 14, wherein, The yaw event is defined by the period between consecutive yaw setpoint commands received from the controller, and the yaw event includes at least five sampling intervals.

19. The system according to claim 14, wherein, Adjusting the second yaw angle of the wind turbine further includes aligning the environmental sensor of the wind turbine with or recalibrating the environmental sensor of the wind turbine.

20. The system according to claim 14, wherein, The monitored performance parameters include power output.

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