System and method for controlling a wind farm

Abstract

A system and method for controlling a wind farm during low wind speeds are provided. Accordingly, a farm controller designates at least one of a plurality of wind turbines in the wind farm as a designated turbine. When the wind speed acting on the wind farm is below a wind speed threshold, the designated turbine operates in a full assist mode. The remaining wind turbines operate in a reduced assist mode. The reduced assist mode includes disabling at least one of pitch and yaw of the remaining wind turbines. When the power output of the designated wind turbine exceeds a power threshold, the farm controller directs at least one group of the remaining wind turbines to transition from the reduced assist mode to the full assist mode. During certain grid conditions, transitions between the assist modes may be delayed.

Description

Technical Field

[0001] The present disclosure relates generally to wind farms and, more particularly, to systems and methods for controlling a wind farm at low wind speeds. Background Art

[0002] Wind power is considered one of the cleanest and most environmentally friendly energy sources currently available, and wind turbines have received increasing attention in this regard. A modern wind turbine typically includes a tower, a generator, a gearbox, a nacelle, and one or more rotor blades. The nacelle includes a rotor assembly coupled to the gearbox and the generator. The rotor assembly and the gearbox are mounted on a base support frame located within the nacelle. The one or more rotor blades capture the kinetic energy of the wind using the known airfoil principle. The rotor blades transmit kinetic energy in the form of rotational energy to rotate a shaft that couples the rotor blades to the gearbox, or directly to the generator if a gearbox is not used. The generator then converts the mechanical energy into electrical energy, and the electrical energy can be transmitted to a frequency converter and / or transformer housed in the tower and subsequently deployed to a multi-purpose power grid. Modern wind power production systems typically take the form of a wind farm having multiple such wind turbine generators that are operable to supply electricity to a transmission system that provides power to the power grid.

[0003] Capturing the kinetic energy of the wind typically involves pitching the rotor blades of one or more wind turbines within a wind farm and / or yawing the nacelles to orient the rotor blades relative to the wind. Pitching and yawing are typically performed via a pitch and yaw system that employs pitch and yaw motors. Typically, the pitch and yaw motors draw power from the grid. However, the amount of power drawn from the grid reduces the net value of the power supplied to the grid by the wind farm. When wind speeds are relatively low, a point may be reached at which the amount of power required from the grid may exceed the amount of power that can be produced by the wind farm. Thus, when wind speeds are relatively low, it may be desirable to limit the power draw of the wind farm.

[0004] As wind speeds increase from relatively low speeds, it may be desirable to increase the power draw of a wind farm to boost power generation by the wind turbines. This increase in power draw from individual wind turbines may cause the wind farm to present a demand signal to the grid. Thus, it may be desirable to synchronize the demand signal from the wind farm with the power availability within the grid.

[0005] Thus, the art is continually seeking new and improved methods for operating a wind farm during low wind speeds and thereafter returning the wind farm to a power producing configuration. Accordingly, the present disclosure is directed to systems and methods for controlling a wind farm during low wind speeds. Summary of the Invention

[0006] Aspects and advantages of the invention will be set forth in part in the description which follows, or may be obvious from the description, or may be learned through practice of the invention.

[0007] In one aspect, the present disclosure is directed to a method for controlling a wind farm during low wind speeds. The wind farm may have a plurality of wind turbines operably coupled to a farm controller and a power grid. The method may include monitoring a wind profile of wind affecting the wind farm. The profile may include wind speed and wind direction. The method may include designating, with the farm controller, at least one of the plurality of wind turbines as a designated wind turbine. When the wind speed of the wind farm is below a wind speed threshold, the designated wind turbine may be operated in a full assist mode. The full assist mode may include enabling at least pitch and yaw of the designated wind turbine. The method may also include operating the remaining wind turbines of the plurality of wind turbines in a reduced assist mode when the wind speed of the wind farm is below the wind speed threshold. The reduced assist mode may include disabling at least one of pitch, yaw, or other system loads of the remaining wind turbines. When the power output of the designated wind turbine exceeds a power threshold, the method may include directing, with the park controller, at least one group of the remaining wind turbines to transition from the reduced assistance mode to the full assistance mode.

[0008] In one embodiment, before directing the at least one group of the remaining wind turbines to transition from the reduced assistance mode, the method may include utilizing, with the park controller, a grid demand signal received from the power grid to determine a power availability level within the power grid.

[0009] In a further embodiment, transitioning the at least one group from the reduced assist mode may further include delaying the transition until the power availability within the power grid exceeds a threshold.

[0010] In an additional embodiment, the method may include, in response to a detected power availability shortage within the power grid, accelerating the transition of the at least one group from the reduced assist mode to supply power to the power grid.

[0011] In one embodiment, the method may include analyzing, with the park controller, a grid demand signal received from the power grid to determine a power availability level within the power grid. Based on the determined power availability level, the method may include lowering, with the park controller, the wind speed threshold to delay transitioning the remaining wind turbines of the plurality of wind turbines to a reduced assist mode. Delaying the transition to the reduced assist mode may facilitate wind farm power production at reduced wind speeds to meet the demand signal from the power grid.

[0012] In an embodiment, designating at least one of the plurality of wind turbines as the designated wind turbine may include selecting, with the park controller, the at least one of the plurality of wind turbines based on a power production profile of each of the plurality of wind turbines for the monitored wind profile.

[0013] In a further embodiment, the method may include predicting, with the park controller, a performance profile of the designated wind turbine with respect to the wind affecting the wind farm, wherein the prediction is based on the power production profile. The method may also include correlating, with the park controller, the predicted performance profile with a recorded performance profile of the designated wind turbine. Additionally, the method may include improving, with the park controller, the power production profile of the designated wind turbine based on the correlation.

[0014] In one embodiment, the wind profile may further include a pressure gradient. Additionally, determining the designated wind turbines may further include: predicting, with the park controller, a wind speed below the wind speed threshold for a limited duration based on the pressure gradient. The method may further include increasing the number of designated wind turbines based on the predicted duration of the wind speed below the wind speed threshold.

[0015] In an additional embodiment, transitioning the at least one group of the remaining wind turbines to the fully assisted mode may further include selecting, with the park controller, wind turbines of the at least one group of the remaining wind turbines based on a power production profile of each wind turbine of the plurality of wind turbines with respect to the monitored wind profile.

[0016] In an embodiment, the method may include initiating a safety override to transition at least one of the remaining wind turbines from the reduced assist mode.

[0017] In a further embodiment, operating the remaining wind turbines in a reduced assistance mode comprises temporarily decoupling the remaining turbines from the power grid.

[0018] In yet a further embodiment, the lite assist mode may further include disabling at least one of: a fan, a pump, an interior light source, a de-icing system, a heater, and power electronics.

[0019] In another aspect, the present disclosure is directed to a method for controlling a wind farm to modify a draw profile presented to a power grid. The wind farm may have a plurality of wind turbines operably coupled to a farm controller and a power grid. The method may include operating a designated wind turbine of the plurality of wind turbines in a full assist mode. The method may also include operating the remaining wind turbines of the plurality of wind turbines in a reduced assist mode until the power output of the designated wind turbine exceeds a power threshold. The reduced assist mode may include disabling at least one of pitch and yaw of the remaining wind turbines. Additionally, the method may include receiving, with the farm controller, a grid signal from the power grid indicating power availability within the power grid at a monitored wind speed. The method may include determining, with the farm controller, a power draw associated with transitioning each of the remaining wind turbines from the reduced assist mode to the full assist mode. The method may also include determining, with the farm controller, a draw profile for the wind farm corresponding to transitioning the wind farm to a power production state. Transitioning the wind farm to the power production state may be based at least in part on the power draw associated with transitioning each of the remaining wind turbines. Recall that the method may include determining, with the park controller, a transition sequence for the remaining wind turbines to modify the draw profile of the wind farm during the transition. The method may also include transitioning the remaining wind turbines to the full assist mode according to the transition sequence.

[0020] In one embodiment, determining the transition sequence for the remaining wind turbines may include, using the park controller, dividing the remaining wind turbines into a plurality of wind turbine groups. The number of wind turbine groups may be selected to extend the transition period of the wind farm from the reduced assistance mode to the full assistance mode. Additionally, the method may include, using the park controller, sequencing the plurality of wind turbine groups in a serial arrangement.

[0021] In a further embodiment, the method may include defining, with the park controller, at least one delay interval. Additionally, the method may include inserting, with the park controller, the delay interval(s) between at least two of the plurality of wind turbines arranged in series.

[0022] In yet a further embodiment, determining the transition order of the remaining wind turbines includes: grouping, with the park controller, the remaining wind turbines into a plurality of wind turbine groups based on a power draw associated with transitioning from the reduced assistance mode to the full assistance mode determined for each wind turbine. Grouping the wind turbines based on the determined power draw may reduce a peak power draw of the draw profile.

[0023] In an additional embodiment, determining the transition sequence of the remaining wind turbines may include deriving, with the park controller, a power production potential of the wind farm at the monitored wind speed based at least in part on the power output of the designated wind turbine. The method may further include determining, with the park controller, a ratio of the power production potential to the draw profile. Additionally, the method may include synchronizing, with the park controller, the transition sequence of the remaining wind turbines with the power availability within the power grid based on the ratio.

[0024] In an embodiment, after the power output of the designated wind turbine(s) exceeds the power threshold, the method may include delaying transition of the remaining wind turbines to the full assist mode until later in the day.

[0025] In an embodiment, the grid signal may indicate a high level of power availability within the power grid, and the method may include increasing the power threshold in order to delay the transitioning of the remaining wind turbines.

[0026] In yet a further embodiment, determining the transition order of the remaining wind turbines may include monitoring a wind profile of wind affecting the wind farm. The profile may include the wind speed and wind direction. The method may include selecting, with the farm controller, at least one group of the remaining wind turbines based on a power production profile of each of the remaining wind turbines with respect to the monitored wind profile.

[0027] These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims.The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] A full and enabling disclosure (to one skilled in the art) of the invention, including the best mode thereof, is set forth in this specification, which references the accompanying drawings, in which:

[0029] Figure 1 A perspective view illustrating one embodiment of a wind turbine according to the present disclosure;

[0030] Figure 2 shows a perspective view of the interior of one embodiment of a wind turbine nacelle according to the present disclosure;

[0031] Figure 3 A schematic diagram illustrating one embodiment of a wind farm having a plurality of wind turbines according to the present disclosure;

[0032] Figure 4 shows a top view of one embodiment of a wind farm having a plurality of wind turbines according to the present disclosure;

[0033] Figure 5 Shown for use with Figure 3 A schematic diagram of an embodiment of a controller for use with a wind farm as shown in FIG;

[0034] Figure 6 A schematic diagram illustrating one embodiment of control logic for a system for operating a wind farm according to the present disclosure;

[0035] Figure 7 Show Figure 6 a schematic diagram of a portion of a control logic for controlling a wind farm with respect to modifying a draw profile presented to a power grid during a transition from a reduced assistance mode to a full assistance mode, in particular illustrating an embodiment of the control logic according to the present disclosure; and

[0036] 8a and 8b present graphical representations of draw profiles presented to a power grid according to the present disclosure;

[0037] Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention. DETAILED DESCRIPTION

[0038] 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 as an explanation of the present invention, rather than as a limitation of the present invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made without departing from the scope or spirit of the present invention. For example, the features shown or described as part of an embodiment can be used together with another embodiment to derive further embodiments. Therefore, the present invention is intended to encompass such modifications and variations that follow within the scope of the appended claims and their equivalents.

[0039] Unless otherwise specified herein, the terms “coupled,” “fixed,” “attached,” and the like refer not only to direct coupling, fixing, or attachment, but also to indirect coupling, fixing, or attachment through one or more intermediate components or features.

[0040] As used herein throughout the specification and claims, approximating language is applied to modify any quantitative expression that may be permitted to vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by one or more terms such as "about," "approximately," and "substantially" is not to be limited to the precise value specified. In at least some instances, approximating language may correspond to the accuracy of an instrument used to measure a value, or the accuracy of a method or machine used to construct or manufacture a component and / or system. For example, an approximate language may refer to being within a 10 percent tolerance.

[0041] Here and throughout the specification and claims, range limitations are combinable and interchangeable, and unless context or language indicates otherwise, such ranges are identified and include all sub-ranges contained therein. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other.

[0042] In general, the present disclosure is directed to systems and methods for controlling a wind farm connected to a power grid. In particular, the present disclosure may include systems and methods for facilitating wind farm operation during periods of low wind speeds. Specifically, the present disclosure may include monitoring wind profiles to detect wind speeds approaching a predetermined threshold. When approaching the predetermined wind speed threshold is detected, a farm controller may implement a control scheme to minimize power draw from the wind farm while maintaining readiness to return to power production.

[0043] To maintain readiness to return to power production, the park controller may designate at least one of the plurality of wind farm turbines as a designated wind turbine to be operated in a full or normal assist mode as wind speed drops below a wind speed threshold. In other words, the designated wind turbine(s) may be maintained in a fully operational configuration, capable of pitching and yawing as necessary to attempt to catch the wind and generate power.

[0044] To reduce the power draw of the wind farm, the remaining wind turbines in the wind farm may be operated in a reduced-assist mode when the wind speed is below a wind speed threshold. The reduced-assist mode may include disabling at least one of pitch, yaw, and other system loads on the remaining wind turbines. In reduced-assist mode, the power draw of the remaining wind turbines is reduced because the wind turbines may not pitch and / or yaw to catch the wind when wind speeds are too low. In other words, the remaining wind turbines may not consume a significant amount of power at wind speeds that do not support sufficient power generation. The sufficiency of power generation may be determined based on the magnitude of the power generation or the profitability of the power generation.

[0045] According to the present disclosure, the system can maintain the remaining wind turbines in a reduced assist mode until the power output of the designated wind turbine(s) exceeds a power threshold. In other words, the designated wind turbine(s) can serve as scout turbine(s) for the wind farm. As scouts, the designated wind turbine(s) can indicate when wind speeds are sufficient to support power production by the remaining turbines, thereby indicating that a condition exists to adjust the power draw of the remaining turbines.

[0046] Once the power output of the designated wind turbine(s) exceeds a power threshold, the park controller may initiate a transition of at least a portion of the remaining wind turbines from the reduced assist mode. Because the remaining wind turbines may pitch and / or yaw to catch the wind and resume power generation, the wind farm may present a relatively significant demand signal to the power grid. It will be appreciated that in order to synchronize the demand signal with power availability on the power grid, it may be desirable to shape the demand signal through the order / timing of the transitions of the remaining wind turbines.

[0047] The present disclosure may also include one of the remaining wind turbines producing electricity. When producing electricity, the wind turbine may be a net producer. As the wind speed decreases, the wind turbine may transition from a net producer to a net consumer because the wind turbine's electricity production falls below the wind turbine's electricity consumption. In response to this, the wind turbine may transition to a reduced assist mode. The reduced assist mode may be equivalent to a temporary, quasi-parked state using as little yaw and pitch as possible. The quasi-parked state may be sustainable for a limited time period, but may not be ideal if maintained for an extended period. Once the wind speed increases, or the grid conditions change, the wind turbine may transition to normal (full) assist mode. From the full assist mode, the wind turbine may (as indicated by the conditions) either draw such electricity as may be required to completely shut down the wind turbine, or may return to a power producing state.

[0048] Referring now to the accompanying drawings, Figure 1A perspective view of one embodiment of a wind turbine 100 according to the present disclosure is shown. As shown, the wind turbine 100 generally includes a tower 102 extending from a support plane 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 an alternative embodiment, the rotor 108 may include more or less than three rotor blades 112. Each rotor blade 112 may be spaced about the hub 110 to facilitate rotating the rotor 108 so that kinetic energy can be converted from the wind into usable mechanical energy and, subsequently, into electrical energy. For example, the hub 110 may be rotatably coupled to an electrical generator 118 ( Figure 2 ) to allow electrical energy to be produced.

[0049] The wind turbine 100 may also include a turbine controller 162 ( Figure 2 ) of the cabin controller 200 ( Figure 5 ). However, in other embodiments, turbine controller 162 may be located within any other component of the wind turbine, or at a location external to the wind turbine. Further, turbine controller 162 may be communicatively coupled to any number of components of wind turbine 100 to control the components. As such, wind turbine 162 may include a computer or other suitable processing unit. Thus, in several embodiments, wind turbine 162 may include suitable computer-readable instructions that, when implemented, configure turbine controller 162 to perform various functions, such as receiving, transmitting, and / or executing wind turbine control signals.

[0050] Now refer to Figure 2 , showing Figure 1, a simplified internal diagram of one embodiment of a nacelle 106 of a wind turbine 100 is shown in FIG. As shown, a generator 118 may be coupled to the rotor 108 for generating electricity 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 therewith. The rotor shaft 122 may be rotatably supported by main bearings 144. The rotor shaft 122 may, in turn, be rotatably coupled to a high-speed shaft 124 of the generator 118 via a gearbox 126, which is connected to a base support frame 136 via one or more torque arms 142. As is generally understood, in response to the rotation of the rotor blades 112 and the hub 110, the rotor shaft 122 may provide a low-speed, high-torque input to the gearbox 126. 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, thereby, the generator 118.

[0051] 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 a turbine controller 162. Further, each pitch control mechanism 120 may include a pitch drive motor 128, a pitch drive gearbox 130, and a pitch drive pinion 132. The pitch drive 128 may be powered by a power grid 166 ( Figure 3) draws electrical power. In such embodiments, pitch drive motor 128 may be coupled to pitch drive gearbox 130 such that pitch drive motor 128 transmits mechanical force to pitch drive gearbox 130. Similarly, pitch drive gearbox 130 may be coupled to pitch drive pinion 132 for rotation therewith. Pitch drive pinion 132 may, in turn, be in rotational engagement with a pitch bearing 134 coupled between hub 110 and a corresponding rotor blade 112 such that pitch drive pinion 132 rotates pitch bearing 134. Thus, in such embodiments, rotation of pitch drive motor 128 drives pitch drive gearbox 130 and pitch drive pinion 132, thereby rotating pitch bearing 134 and rotor blade(s) 112 about pitch axis 116. Similarly, wind turbine 100 may include one or more yaw drive mechanisms 138 communicatively coupled to turbine controller 162, wherein each (or each) yaw drive control mechanism 138 is configured to change the angle of nacelle 106 relative to the wind (e.g., by engaging a yaw axis 140 of wind turbine 100). It should be appreciated that turbine controller 162 may direct the yaw of nacelle 106 and / or the pitch of rotor blades 112 to aerodynamically orient wind turbine 100 relative to the wind (W) acting on wind turbine 100, thereby facilitating power production.

[0052] Now refer to Figure 3 , a schematic diagram of a wind farm 152 controlled according to the systems and methods of the present invention is shown. As shown, the wind farm 152 may include a plurality of wind turbines 100 as described herein and a controller 200 configured as a farm controller 164. For example, as shown in the illustrated embodiment, the wind farm 152 may include 12 wind turbines 100. However, in other embodiments, the wind farm 152 may include any other number of wind turbines 100, such as fewer than 12 wind turbines 100 or more than 12 wind turbines 100. In one embodiment, the turbine controller(s) 162 of the turbine(s) 100 may be communicatively coupled to the farm controller 164 via a wired connection, such as connecting the turbine controller(s) 162 via a suitable communication link 154 (e.g., a suitable cable). Alternatively, the wind turbine(s) 162 may be communicatively coupled to the farm controller 164 via a wireless connection, such as by using any suitable wireless communication protocol known in the art.

[0053] In several embodiments, wind farm 152 may include a plurality of environmental sensors 156 for monitoring the wind distribution of wind (W) affecting wind farm 152. Environmental sensors 156 may be configured to collect data indicative of at least one environmental condition. Environmental sensors 156 may be operably coupled to farm controller 164 and to turbine controller 162. Thus, in one embodiment, environmental sensor(s) 156 may be, for example, a wind vane, anemometer, lidar sensor, thermometer, barometer, or other suitable sensor. Data collected by environmental sensor(s) 156 may include measurements of wind speed, wind direction, wind shear, wind gust, wind veer, atmospheric pressure, pressure gradient, and / or temperature. In at least one embodiment, environmental sensor(s) 156 may be mounted on nacelle 106 at a location downwind of rotor 108. It should be appreciated that environmental sensor(s) 156 may comprise a network of sensors and may be located remotely from turbine(s) 100. It should be appreciated that environmental conditions may vary significantly across wind farm 152. Accordingly, environmental sensor(s) 156 may allow local environmental conditions (such as local wind speed) at each wind turbine 100 to be monitored individually by respective turbine controllers 162 and jointly by park controller 164.

[0054] Still refer to Figure 3 In one embodiment, the farm controller 164 may also be operably coupled to at least one grid sensor 160. The grid sensor(s) 160 may be operably coupled to the power grid 166. The grid sensor(s) 160 may be configured to detect data indicating the availability of power within the power grid 166. The power availability may be interpreted by the farm controller 164 as a grid demand signal 302 ( Figure 6 ).

[0055] It should be appreciated that power availability can be correlated with fluctuations in power drawn from and delivered to power grid 166. Accordingly, the value of power provided to or drawn from power grid 166 can vary with power availability. For example, a grid operator may offer a higher utility rate for power provided during periods of relatively low availability, while also charging a higher utility rate for power drawn from the grid during the same periods. Thus, it may be desirable to synchronize the operation of wind farm 152 with power availability, as indicated by grid demand signal 302.

[0056] Now refer to Figure 4, illustrates a top view of one embodiment of a wind farm 152. In one embodiment, as shown, the plurality of wind turbines 100 of the wind farm 152 may be positioned according to the topography of the wind farm 152. For example, the wind farm 152 may have at least one portion at a higher elevation than adjacent portions, as shown by topographic line 168. It should be appreciated that the distribution of the wind turbines 100 of the wind farm 152 and the topography of the wind farm 152 may cause the wind (W) to affect the wind turbines 100 in an unequal manner.

[0057] Now refer to Figure 5 - Figure 8b presents a schematic diagram of various embodiments of a system 300 for controlling a wind farm 152 according to the present disclosure. In particular, Figure 5 , a schematic diagram illustrating one embodiment of suitable components that may be included within the controller 200 is shown. For example, as shown, the controller 200 may include one or more processors 206 and associated memory device(s) 208 configured to perform various computer-implemented functions (e.g., perform methods, steps, calculations, and the like and store related data as disclosed herein). Additionally, the controller 200 may also include a communication module 210 to facilitate communication between the controller 200 and the wind turbine 100 and components therein. Further, the communication module 210 may include sensors 212 (e.g., one or more analog-to-digital converters) to permit signals transmitted from one or more sensors 156, 160 to be converted into signals that can be understood and processed by the processor 206. It should be appreciated that the sensors 156, 160 may be communicatively coupled to the communication module 210 using any suitable means. For example, as Figure 5 As shown in , sensors 156, 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 operably coupled to an operating state control module 214 configured to change at least one wind turbine operating state.

[0058] As used herein, the term "processor" refers not only to integrated circuits as 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, the memory device(s) 208 may generally include, but are not limited to, the following memory element(s): computer-readable media (e.g., random access memory (RAM)), computer-readable non-volatile media (e.g., flash memory), floppy disks, compact disk read-only memory (CD-ROMs), magneto-optical disks (MODs), digital versatile disks (DVDs), and / or other suitable memory elements. Such memory device(s) 208 may generally be configured to store suitable computer-readable instructions that, when implemented by the processor(s) 206, configure the controller 202 to perform various functions including, but not limited to, controlling the wind farm 152 during low wind speeds and modifying the draw profile presented to the power grid 166 during a transition of the wind farm 152 from a reduced assist mode (as described herein), as well as various other suitable computer-implemented functions.

[0059] Special reference Figure 6 In one embodiment, the park controller 164 of the system 300 can be configured to monitor a wind profile 304 of wind (W) affecting the wind farm 152. The wind profile 304 can include wind speed, wind direction, pressure gradient, and / or variability indicators. Data indicating the wind profile 304 can be received from the environmental sensor(s) 156.

[0060] As indicated at 306, in one embodiment, park controller 164 may detect wind speed approaching a wind speed threshold. The wind speed threshold may be a predetermined wind speed at which modifying the operating state of wind turbine 100 to attempt to generate electricity may no longer be desirable. As such, it should be appreciated that the wind speed threshold may, in one embodiment, be represented as an electricity threshold. At this threshold, the value of the electricity produced by the wind farm may be substantially equal to the cost of production. The cost of production may include at least one of the electricity rate charged by the grid operator for electricity drawn from power grid 166 and a variable that reduces the remaining useful life of components of wind turbine 100. As wind speed decreases below the wind speed threshold, the cost of production may exceed the value of the electricity being produced by wind farm 152. For example, the amount charged by the grid operator for electricity consumed to power auxiliary systems of wind turbine 100 may exceed the value of the electricity that can be produced at relatively low wind speeds.

[0061] In at least one embodiment, park controller 164 may receive a grid demand signal 302 indicating that it may be desirable to continue generating power at lower wind speeds than would otherwise be desirable. As such, park controller 164 may analyze grid demand signal 302 to determine a level of power availability within power grid 166. Based on the determined level of power availability, park controller 164 may, at 308, lower the wind speed threshold to delay transitioning at least a portion of wind turbines 100 to the reduced assist mode in order to satisfy demand signal 302. For example, in one embodiment, grid demand signal 302 may indicate relatively low power availability within power grid 166. In such an embodiment, the value of the power supplied to the power grid may be such that even the reduced power production of wind farm 152 at lower wind speeds may outweigh the costs associated with drawing power from power grid 166. In an additional embodiment, the relatively low power availability within the power grid may indicate that the cost of drawing power from the grid during the transition may exceed the costs associated with continuing to operate wind farm 152 in the full assist mode. It should be appreciated that wind turbine 100 may be in full assist mode when in a normal power production state or when wind turbine(s) 100 are net consumers of power. For example, in one embodiment, reduced assist mode may be a quasi-shutdown state using minimal yaw and pitch control. In such an embodiment, portions of wind turbine 100 may be temporarily transitioned to full assist mode to facilitate a complete shutdown of wind turbine 100.

[0062] As shown at 310, in one embodiment, the park controller 164 may designate at least one of the plurality of wind turbines 100 as a designated wind turbine 312. Regardless of wind speed, the designated wind turbine(s) 312 may be operated in a fully assisted mode. In particular, when the wind speed of the wind (W) affecting the wind farm 152 is below a wind speed threshold, the designated wind turbine(s) 312 may be operated in the fully assisted mode. The fully assisted mode may include at least enabling pitch and yaw of the designated wind turbine(s) 312. It should be appreciated that the fully assisted mode may be the nominal operating mode of the wind turbine(s) 100.

[0063] In at least one embodiment, the farm controller 164 may select at least one of the plurality of wind turbines 100 based on the power production profile of each wind turbine of the plurality of wind turbines 100 for the monitored wind profile 304. For example, in one embodiment, the designated wind turbine(s) 312 may be wind turbine(s) 100 that exhibit similar power generation under prevailing wind conditions. Alternatively, the designated wind turbine(s) 312 may have an average power generation capability relative to the plurality of wind turbines 100. It should be appreciated that selecting the designated wind turbine(s) 312 that have an average or below-average power generation capability for prevailing wind conditions may ensure that the power generation level from the designated wind turbine(s) 312 can be predictably achieved by the other wind turbines 100 in the wind farm 152.

[0064] In an additional embodiment, the designated wind turbine(s) 312 may be wind turbines 100 positioned at a particular advantageous or disadvantageous location relative to the wind (W) affecting the wind farm 152. For example, the designated wind turbine(s) 312 may be wind turbine(s) 100 positioned at the highest elevation of the wind farm 152 and / or along a portion of the outer edge of the wind farm 152, upwind of other wind turbines 100. Alternatively, the designated wind turbine(s) 312 may be positioned at an unfavorable location, such as in a wind shadow or other area of ​​disturbed wind flow. Selecting a wind turbine 100 at an unfavorable location may result in the designated wind turbine(s) 312 having a power generation capacity that could be foreseeably achieved by other wind turbines 100 in more favorable locations.

[0065] In a further embodiment, the designated wind turbine(s) 312 may be a plurality of designated wind turbines, such as in Figure 4 The plurality of designated wind turbines 312 may be selected for any of the aforementioned reasons regarding power production capacity and positioning within wind farm 152 .

[0066] In at least one embodiment, the system 300 may include a feedback mechanism configured to improve the performance profile selection of the designated wind turbine(s) 312. Thus, the park controller 164 may predict the performance profile of the designated wind turbine(s) 312 for wind (W) affecting the wind farm 152. The prediction may be based on the historical power production profile of the designated wind turbine(s) 312. The park controller 164 may correlate the predicted performance profile with the performance profile recorded while operating as the designated wind turbine(s) 312. Based on this correlation, the park controller 164 may improve the power production profile of the designated wind turbine(s) 312.

[0067] In one embodiment, the park controller 164 may determine whether the wind speed is below a wind speed threshold at 314. As shown at 316, in one embodiment, where the wind speed is above the wind speed threshold, the plurality of wind turbines 100 of the wind farm 152 may be operated in a full assist mode.

[0068] As shown at 330, in one embodiment, based on the pressure gradient of wind profile 304, park controller 164 may predict that the wind speed will be below a wind speed threshold for a limited duration. In such an embodiment, park controller 164 may, as shown at 332, increase the number of designated wind turbine(s) 312. In one embodiment, the number of designated wind turbine(s) 312 may be based on the predicted duration of the wind speed below the wind speed threshold. It should be appreciated that, in one embodiment, the number of designated wind turbines 312 may be all of the wind turbines 100 in wind farm 152 so that all of wind turbines 100 maintain operation during a relatively brief drop in wind speed below the wind speed threshold.

[0069] In one embodiment, where the wind speed is below the wind speed threshold, wind farm 164 may initiate a transition of wind farm 152 to the reduced extraction mode, as shown at 314. In the reduced extraction mode, system 300 may operate the designated wind turbine(s) in the full assist mode at 318 and operate the remaining wind turbines 322 in the reduced assist mode at 320.

[0070] In one embodiment, the reduced assist mode may include disabling pitch and / or yaw of the remaining wind turbines 322. The reduced assist mode may also include disabling fans, pumps, internal lighting, de-icing systems, heaters, and / or power electronics (e.g., VAR generation) of the remaining wind turbines 322 in one embodiment. In a further embodiment, the reduced assist mode may include temporarily decoupling the remaining wind turbines 322 from the power grid 166. In the reduced assist mode, the remaining wind turbines 322 may, for example, Figure 4, no attempt is made to maintain aerodynamic alignment with the wind (W). It should be appreciated that because at least a portion of the auxiliary systems of the remaining wind turbines 322 can be disabled, the power draw from the power grid by the remaining wind turbines 322 can also be reduced. In at least one embodiment, reducing the draw from the power grid can result in cost savings for the wind farm operator.

[0071] In one embodiment, the reduced assist mode may include classifying the power consuming components of the wind turbine(s) 100 into two categories. The first category may include those power consuming components of the wind turbine(s) 100 that are deemed safety-critical. The power electronics of the safety-critical components may be maintained at a temperature above a safety-critical limit. The safety-critical limit may be a temperature at which the component blocks grid energy from entering the unstarted machine (because such an event could cause a catastrophic failure of the electronic system). The second category may include those power consuming components of the wind turbine(s) 100 that are deemed operationally critical. The power electronics of the operationally critical components may be maintained above the safety-critical limit and at a temperature that allows the machine to be safely started.

[0072] As in Figure 5 As shown at 324, the park controller 164 of the system 300 may be configured to detect that the power output of the designated wind turbine(s) 312 exceeds a power threshold. The power threshold may be established by the park controller 164 at a level at which the value of the power generated from the designated wind turbine(s) 322 exceeds the cost associated with aerodynamically aligning the designated wind turbine(s) 312 with the wind (W) (e.g., the cost of power drawn from the power grid 166 when driving auxiliary systems of the designated wind turbine(s) 312).

[0073] In one embodiment, the park controller 164 may, as shown at 326, direct at least one group (such as the first group 328) of the remaining wind turbines 322 to transition from a reduced assistance mode to a full assistance mode when the power output of the designated wind turbine(s) 312 exceeds a power threshold. For example, in such embodiments, the park controller 164 may enable pitch and / or yaw of the wind turbines 100 in the first group 328. It should be appreciated that, in one embodiment, transitioning the first group 328 may include transitioning all of the remaining wind turbines 322 in the wind farm 152 to a full assistance mode.

[0074] As shown at 334, in one embodiment, before directing first group 328 of remaining wind turbines 322 to transition from the lean assist mode, park controller 164 may analyze grid demand signal 302 to determine the level of power availability within power grid 166. In one embodiment, park controller 164 may detect a power availability shortage within power grid 166 at 336. In such an embodiment, the value of any generated power provided to power grid 166 may be greater than the value of generated power provided to power grid 166 during periods of excess power within power grid 166. Therefore, a power availability shortage may indicate an opportunity. As shown at 338, park controller 164 may accelerate the transition of first group 328 from the lean assist mode in order to capitalize on the opportunity by supplying power to power grid 166.

[0075] Still refer to Figure 6 At 334, in one embodiment, grid demand signal 302 may indicate sufficient power availability within power grid 166. In response, park controller 164 may determine at 340 whether a power availability level within power grid 166 exceeds a threshold. The threshold may be a power availability level above which the rate for drawing power from power grid 166 may be reduced, thereby reducing the costs associated with transitioning first group 328. In one embodiment, where power availability does not exceed the threshold, park controller 164 may continue to operate remaining wind turbines 322 in the reduced assist mode at 342. By doing so, park controller 164 may delay transitioning first group 328 until power availability within the power grid exceeds the threshold.

[0076] As shown at 344, in one embodiment, park controller 164 may select wind turbines 100 from a first group 328 of remaining wind turbines 322. In at least one embodiment, the selection of first group 328 may be based on the power production profile of each wind turbine in the plurality of wind turbines 100 with respect to the monitored wind profile 304. For example, park controller 164 may select those wind turbines 100 whose corresponding power production profiles indicate that they can generate the most power at a given wind speed. The power production profiles of wind turbines 100 may reflect the positioning of wind turbines 100 within wind farm 152. As such, the power production profiles may indicate wind turbines 100 with the most advantageous positions with respect to the monitored wind profile 304. In an alternative embodiment, the selection may include those wind turbines 100 whose corresponding power production profiles indicate that they can be transitioned to full assist mode at the lowest cost.

[0077] Still refer to Figure 5In FIG8b , park controller 164 of system 300 may, in one embodiment, modify a draw profile 346 presented to power grid 166 by transitioning at least first group 328 from a reduced assistance mode to a full assistance mode, as shown at 326. For example, unmodified draw profile 348 may, as shown in FIG8a , have a relatively significant peak power draw 362 that occurs for a relatively brief duration. Such a draw profile 346 may indicate a transition of the entirety of remaining wind turbines 322 as a single group. Alternatively, modified draw profile 350 may, as shown in FIG8b , have a reduced peak power draw 362 but may draw power over a longer period of time. Such a draw profile 346 may indicate a sequential and / or delayed transition of remaining wind turbines 322.

[0078] refer to Figure 6 326, such as Figure 7 As expanded, park controller 164 may, in one embodiment, receive grid signal 302 from power grid 166. Based on grid signal 302, park controller 164 may determine power availability within power grid 166, as indicated at 352. Power availability within power grid 166 may indicate the relative value of power drawn from power grid 166 and power provided to power grid 166. Thus, synchronizing draw profile 346 with power availability may facilitate at least one of reducing the cost of transitioning remaining wind turbines 322 and maximizing the value of generated power provided to power grid 166.

[0079] As in Figure 7 As shown at 354 , park controller 164 may, in one embodiment, determine the power draw associated with transitioning each wind turbine 100 of remaining wind turbines 322 from the reduced assistance mode to the full assistance mode. Additionally, as shown at 356 , park controller 164 may determine a power draw profile 346 for wind farm 152 corresponding to transitioning wind farm 152 to the power production state. Transitioning wind farm 152 to the power production state may be based at least in part on the power draw associated with transitioning each wind turbine 100 of remaining wind turbines 322. Based on the draw profile 346 of wind farm 152 and the power availability within power grid 166 , park controller 164 may determine a transition sequence for the remaining wind turbines at 358 . The transition sequence may modify the draw profile 346 of wind farm 152 during the transition. In one embodiment, based on the transition sequence, park controller 164 may transition remaining wind turbines 322 to the full assistance mode by directing a change in the operating state of remaining wind turbines 322.

[0080] Still refer to Figure 7358, in one embodiment, park controller 164 may divide the remaining wind turbines 322 into a plurality of wind turbine groups 360. In one embodiment, the number of groups 360 may be selected to extend the transition period (PoT) of wind farm 152 from the reduced assistance mode to the full assistance mode. Park controller 164 may sequence the plurality of wind turbine groups 360 in a serial arrangement. For example, in at least one embodiment, remaining wind turbines 322 may be divided into three or more groups. In an alternative embodiment, to further extend the transition period (PoT), remaining wind turbines 322 may be divided into six or more groups. It should be appreciated that extending the transition period (PoT) by dividing remaining wind turbines 322 into a plurality of wind turbine groups 360 may be used to synchronize the draw profile 346 of wind farm 152 with the power availability within power grid 166.

[0081] In an additional embodiment, the park controller 164 may also define at least one delay interval. The park controller 164 may insert one or more delay intervals between at least two of the plurality of wind turbine groups 360 arranged in series. For example, in an embodiment where the remaining wind turbines 322 are divided into four wind turbine groups 360, one or more delay intervals may be inserted between each of the four wind turbine groups 360. It will be appreciated that the use of one or more delay intervals may further facilitate synchronization of the draw profile 346 of the wind farm 152 with the power availability within the power grid 166.

[0082] Still refer to Figure 7 358, in one embodiment, based on the power draw associated with the transition from the reduced assistance mode to the full assistance mode determined for each wind turbine 100, the park controller 164 may group the remaining wind turbines 322 into the plurality of wind turbine groups 360. Based on the determined power draw, the grouped wind turbines 100 may reduce the peak power draw 362 of the draw profile 346. It should be appreciated that reducing the peak power draw 362 may be desirable in one embodiment where the rate of electricity drawn from the power grid 166 may be increased if the power draw exceeds a threshold established by the grid operator for a given interval.

[0083] Continue to refer Figure 7 358, in one embodiment, the park controller 164 may derive the power production potential of the wind farm 152 at the monitored wind speed based at least in part on the power output of the designated wind turbine(s) 312. The park controller 164 may determine a ratio that correlates the power production potential of the wind farm to the draw profile 346. Additionally, the park controller 164 may synchronize the transition sequence of the remaining wind turbines 322 with the power availability within the power grid based on the ratio.

[0084] In an additional embodiment, the park controller 164 can modify the extraction profile 346 by delaying the transition of the remaining wind turbines 322 to full assist mode until later in the day. It should be appreciated that this can be particularly advantageous when the wind farm 152 is coupled to a power grid 166 that has electricity rates tied to the time of day rather than to a particular extraction profile. In such an embodiment, delaying the transition until later in the day can result in the remaining wind turbines 322 being transitioned when the costs associated with the transition can be minimized. It should further be appreciated that the transition of the remaining wind turbines 322 can include a partial transition, in which certain attributes are enabled while other attributes remain disabled.

[0085] In one embodiment, grid signal 302 may indicate a relatively high level of power availability within power grid 166. In such an embodiment, modifying draw profile 346 presented to power grid 166 may include increasing a power threshold in order to delay transitioning remaining wind turbines 322. In such an embodiment, the relatively high level of power availability may reduce the value of the power generated and delivered to power grid 166. As a result, additional power production may be required to offset the costs associated with transitioning from the lean assist mode.

[0086] In another embodiment, turbine controller 162 may initiate a safety override to at least partially transition at least one of remaining wind turbines 322 from the lite assist mode. For example, in an embodiment where yaw of wind turbine 100 is disabled in lite assist mode, a change in the direction of wind (W) may result in a crosswind acting on wind turbine 100 that exceeds a load limit of wind turbine 100. Thus, in order to aerodynamically align wind turbine 100 with wind (W), it may be desirable to enable yaw of wind turbine 100.

[0087] Furthermore, those skilled in the art will recognize the interchangeability of various features from different embodiments. Similarly, the various method steps and features described, as well as other known equivalents of each such method and feature, can be mixed and matched by one of ordinary skill in the art to construct additional systems and techniques in accordance with the principles of the present disclosure. Of course, it is to be understood 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 implemented or practiced in a manner that achieves or optimizes one advantage or group of advantages as taught herein, without necessarily achieving other objectives or advantages as may be taught or suggested herein.

[0088] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any included methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantially different literal language from the claims.

[0089] Further aspects of the invention are provided by the subject matter of the following clauses:

[0090] Item 1. A method for controlling a wind farm during low wind speeds, the wind farm having a plurality of wind turbines operably coupled to a farm controller and a power grid, the method comprising: monitoring a wind distribution of wind affecting the wind farm, wherein the distribution includes wind speed and wind direction; designating, with the farm controller, at least one of the plurality of wind turbines as a designated wind turbine; operating the designated wind turbine in a full assist mode when the wind speed of the wind farm is below a wind speed threshold, wherein the full assist mode includes enabling at least pitch and yaw of the designated wind turbine; operating the remaining wind turbines of the plurality of wind turbines in a reduced assist mode when the wind speed of the wind farm is below the wind speed threshold, wherein the reduced assist mode includes disabling at least one of pitch and yaw of the remaining wind turbines; and directing, with the farm controller, at least one group of the remaining wind turbines to transition from the reduced assist mode to the full assist mode when the power output of the designated wind turbine exceeds a power threshold.

[0091] Clause 2. The method of any preceding clause, further comprising: prior to directing said at least one group of said remaining wind turbines to transition from said reduced assist mode, analyzing, with said park controller, a grid demand signal received from said power grid to determine a power availability level within said power grid.

[0092] Clause 3. The method of any preceding clause, wherein transitioning the at least one group from the reduced assist mode further comprises delaying the transition until the power availability level within the power grid exceeds a threshold.

[0093] Clause 4. The method of any preceding clause, further comprising: accelerating the transition of the at least one group from the reduced assist mode in order to supply power to the power grid in response to a detected power availability shortage within the power grid.

[0094] Clause 5. The method of any preceding clause, further comprising: analyzing, with the farm controller, a grid demand signal received from the power grid to determine a power availability level within the power grid; and, based on the determined power availability level, lowering, with the farm controller, the wind speed threshold to delay transitioning the remaining wind turbines of the plurality of wind turbines to the reduced assist mode, wherein delaying the transition to the reduced assist mode facilitates wind farm power production at reduced wind speeds to meet the demand signal from the power grid.

[0095] Clause 6. The method of any preceding clause, wherein designating at least one of the plurality of wind turbines as the designated wind turbine further comprises: selecting, with the park controller, at least one of the plurality of wind turbines based on a power production profile of each wind turbine of the plurality of wind turbines for the monitored wind profile.

[0096] Clause 7. The method of any preceding clause, further comprising: predicting, with the farm controller, a performance profile of the designated wind turbine for the wind affecting the wind farm, wherein the prediction is based on the power production profile; correlating, with the farm controller, the predicted performance profile with a recorded performance profile of the designated wind turbine; and improving, with the farm controller, the power production profile of the designated wind turbine based on the correlation.

[0097] Clause 8. The method of any preceding clause, wherein the wind profile further includes a pressure gradient, determining the designated wind turbines further comprising: predicting, with the park controller, a wind speed below the wind speed threshold for a limited duration based on the pressure gradient; and increasing the number of designated wind turbines based on the predicted duration of the wind speed below the wind speed threshold.

[0098] Clause 9. The method of any preceding clause, wherein transitioning said at least one group of said remaining wind turbines to said fully assisted mode further comprises: selecting, with said park controller, wind turbines of said at least one group of said remaining wind turbines based on a power production profile of each wind turbine of said plurality of wind turbines for a monitored wind profile.

[0099] Clause 10. The method of clause 1, further comprising: initiating a safety override to at least partially transition at least one of the remaining wind turbines from the lite assist mode.

[0100] Clause 11. The method of any preceding clause, wherein operating the remaining turbines in a reduced assist mode comprises temporarily decoupling the remaining turbines from the power grid.

[0101] Clause 12. The method of any preceding clause, wherein the reduced assist mode further comprises disabling at least one of: a fan, a pump, interior lighting, and a de-icing system.

[0102] Clause 13. A method for controlling a wind farm to modify a draw profile presented to an electric power grid, the wind farm having a plurality of wind turbines operably coupled to a farm controller and the electric power grid, the method comprising: operating a designated wind turbine of the plurality of wind turbines in a full assist mode; operating the remaining wind turbines of the plurality of wind turbines in a reduced assist mode until a power output of the designated wind turbine exceeds a power threshold, wherein the reduced assist mode includes disabling at least one of pitch and yaw of the remaining wind turbines; receiving, with the farm controller, a grid signal from the electric power grid indicating power availability within the electric power grid at a monitored wind speed; and a farm controller determining an electrical power draw associated with transitioning each of the remaining wind turbines from the reduced assistance mode to the full assistance mode; determining, with the farm controller, an extraction profile of the wind farm corresponding to transitioning the wind farm to a power production state, wherein transitioning the wind farm to the power production state is based at least in part on the electrical power draw associated with transitioning each of the remaining wind turbines; determining, with the farm controller, a transition sequence for the remaining wind turbines so as to modify the extraction profile of the wind farm during the transition; and transitioning the remaining wind turbines to the full assistance mode according to the transition sequence.

[0103] Clause 14. The method of any preceding clause, wherein determining the transition order of the remaining wind turbines comprises: dividing, with the park controller, the remaining wind turbines into a plurality of wind turbine groups, wherein the number of groups is selected to extend a period of transition of the wind farm from the reduced assistance mode to the full assistance mode; and sequencing, with the park controller, the plurality of wind turbine groups in a serial arrangement.

[0104] Clause 15. The method of any preceding clause, further comprising: defining, with the park controller, at least one delay interval; and inserting, with the park controller, the at least one delay interval between at least two of the plurality of wind turbines arranged in series.

[0105] Clause 16. The method of any preceding clause, wherein determining the transition order of the remaining wind turbines comprises: dividing, with the park controller, the remaining turbines into a plurality of wind turbine groups based on a power draw associated with transitioning from the reduced assistance mode to the full assistance mode determined for each wind turbine, wherein grouping the wind turbines based on the determined power draw reduces a peak power draw of the draw distribution.

[0106] Clause 17. The method of any preceding clause, wherein determining the transition order of the remaining wind turbines comprises: deriving, with the park controller, a power production potential of the wind farm at the monitored wind speed based at least in part on the power output of the at least one designated wind turbine; determining, with the park controller, a ratio of the power production potential to the draw profile; and synchronizing, with the park controller, the transition order of the remaining wind turbines with the power availability within the power grid based on the ratio.

[0107] Clause 18. The method of any preceding clause, further comprising: delaying transitioning the remaining wind turbines to the full assist mode until later in the day after the power output of the designated wind turbine exceeds the power threshold.

[0108] Clause 19. The method of any preceding clause, wherein the grid signal indicates a high level of power availability within the power grid, the method further comprising: increasing the power threshold to delay the transitioning of the remaining wind turbines.

[0109] Clause 20. The method of any preceding clause, wherein determining the transition order of the remaining wind turbines comprises: monitoring a wind profile of wind affecting the wind farm, wherein the profile includes the wind speed and wind direction; and selecting, with the farm controller, at least one group of the remaining wind turbines based on a power production profile of each of the remaining wind turbines for the monitored wind profile.

Claims

1. A method for controlling a wind farm during low wind speeds, the wind farm having a plurality of wind turbines operatively coupled to a farm controller and a power grid, the method comprising: monitoring a wind distribution of wind affecting the wind farm, wherein the distribution includes wind speed and wind direction; designating, with the park controller, at least one of the plurality of wind turbines as a designated wind turbine; operating the designated wind turbine in a fully assisted mode when a wind speed of the wind farm is below a wind speed threshold, wherein the fully assisted mode includes enabling at least pitch and yaw of the designated wind turbine; operating remaining wind turbines of the plurality of wind turbines in a reduced assist mode when a wind speed of the wind farm is below the wind speed threshold, wherein the reduced assist mode includes disabling at least one of pitch and yaw of the remaining wind turbines; as well as directing, with the park controller, at least one group of the remaining wind turbines to transition from the reduced assistance mode to the full assistance mode when the power output of the designated wind turbine exceeds a power threshold, wherein designating at least one of the plurality of wind turbines as the designated wind turbine further comprises: selecting, with the park controller, the at least one of the plurality of wind turbines based on a power production profile of each of the plurality of wind turbines with respect to the monitored wind profile, and Wherein, the method further comprises: predicting, with the park controller, a performance profile of the designated wind turbine for wind affecting the wind farm, wherein the prediction is based on the power production profile; correlating, with the park controller, a predicted performance profile with a recorded performance profile for the specified wind turbine; and Power production profile of the designated wind turbines is improved with the park controller based on the correlation.

2. The method of claim 1, further comprising: Prior to directing the at least one group of the remaining wind turbines to transition from the reduced assist mode, analyzing, with the park controller, a grid demand signal received from the power grid to determine a power availability level within the power grid.

3. The method according to claim 2, wherein: Transitioning the at least one group from the reduced assist mode further includes delaying the transition until the power availability level within the power grid exceeds a threshold.

4. The method of claim 2, further comprising: In response to a detected power availability shortage within the power grid, the at least one group transitioning from the reduced assist mode is accelerated to supply power to the power grid.

5. The method of claim 1, further comprising: analyzing, with the park controller, a grid demand signal received from the power grid to determine a level of power availability within the power grid; Based on the determined power availability level, lowering, with the park controller, the wind speed threshold value to delay transitioning the remaining wind turbines of the plurality of wind turbines to the reduced assist mode, wherein delaying the transition to the reduced assist mode facilitates wind farm power production at reduced wind speeds to meet a demand signal from the power grid.

6. The method of claim 1, wherein: The wind distribution further includes a pressure gradient, and determining the designated wind turbine further includes: predicting, with the park controller, a wind speed below the wind speed threshold for a limited duration based on the pressure gradient; and Based on the predicted duration of the wind speed below the wind speed threshold, the number of designated wind turbines is increased.

7. The method of claim 1, wherein: Transitioning the at least one group of the remaining wind turbines to the fully assisted mode further comprises: Wind turbines of the at least one group of the remaining wind turbines are selected with the park controller based on a power production profile of each wind turbine of the plurality of wind turbines for the monitored wind profile.

8. The method of claim 1, further comprising: A safety override is initiated to at least partially transition at least one of the remaining wind turbines from the lite assist mode.

9. The method of claim 1, wherein: Operating the remaining wind turbines in the lite assist mode includes temporarily decoupling the remaining wind turbines from the power grid.

10. The method of claim 1, wherein: The lite assist mode further includes disabling at least one of: a fan, a pump, interior lighting, a de-icing system, a heater, and power electronics.

11. A method for controlling a wind farm to modify a draw profile presented to a power grid, the wind farm having a plurality of wind turbines operatively coupled to a farm controller and the power grid, the method comprising: monitoring a wind distribution of wind affecting the wind farm, wherein the distribution includes wind speed and wind direction; Designating, with the park controller, at least one of the plurality of wind turbines as a designated wind turbine includes: selecting, with the park controller, at least one of the plurality of wind turbines based on a power production profile of each wind turbine of the plurality of wind turbines with respect to a monitored wind profile; predicting, with the park controller, a performance profile of the designated wind turbine for wind affecting the wind farm, wherein the prediction is based on the power production profile; correlating, with the park controller, a predicted performance profile with a recorded performance profile for the specified wind turbine; and improving, with the park controller, a power production profile of the designated wind turbine based on the correlation; operating the designated wind turbine of the plurality of wind turbines in a fully assisted mode; operating the remaining wind turbines of the plurality of wind turbines in a reduced assist mode until the power output of the designated wind turbine exceeds a power threshold, wherein the reduced assist mode includes disabling at least one of pitch and yaw of the remaining wind turbines; receiving, with the park controller, a grid signal from the power grid indicating the availability of power within the power grid at a monitored wind speed; determining, with the park controller, a power draw associated with transitioning each of the remaining wind turbines from the reduced assistance mode to the full assistance mode; determining, with the park controller, a draw profile for the wind farm corresponding to transitioning the wind farm to a power producing state, wherein transitioning the wind farm to the power producing state is based at least in part on a power draw associated with transitioning each of the remaining wind turbines; determining, with the park controller, a transition sequence for the remaining wind turbines to modify the extraction profile of the wind farm during the transition; and The remaining wind turbines are transitioned to the full assist mode according to the transition sequence.

12. The method of claim 11, wherein: Determining the transition order of the remaining wind turbines includes: dividing the remaining wind turbines into a plurality of wind turbine groups with the park controller, wherein the number of groups is selected to extend a period of transition of the wind farm from the reduced assistance mode to the full assistance mode; and The plurality of wind turbines are sequenced in a serial arrangement using the park controller.

13. The method of claim 12, further comprising: defining at least one delay interval with the field controller; as well as The at least one delay interval is inserted with the park controller between at least two of the plurality of wind turbines arranged in series.

14. The method of claim 11, wherein: Determining the transition order of the remaining wind turbines includes: The remaining wind turbines are divided, with the park controller, into a plurality of wind turbine groups based on a power draw associated with transitioning from the reduced assistance mode to the full assistance mode determined for each wind turbine, wherein grouping the wind turbines based on the determined power draw reduces a peak power draw of the draw profile.

15. The method of claim 11, wherein: Determining the transition order of the remaining wind turbines includes: deriving, with the park controller, a power production potential of the wind farm at the monitored wind speed based at least in part on the power output of the at least one designated wind turbine; determining, with the park controller, a ratio of the power production potential to the draw profile; and A transition sequence of the remaining wind turbines is synchronized with the power availability within the power grid based on the ratio with the park controller.

16. The method of claim 11, further comprising: After the power output of the designated wind turbine exceeds the power threshold, transitioning the remaining wind turbines to the full assist mode is delayed until later in the day.

17. The method of claim 11, wherein: The grid signal indicates a high level of power availability within the power grid, the method further comprising: The power threshold is increased to delay transitioning of the remaining wind turbines.

18. The method of claim 11, wherein: Determining the transition order of the remaining wind turbines includes: At least one group of the remaining wind turbines is selected with the park controller based on a power production profile of each of the remaining wind turbines for the monitored wind profile.

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