Wind farm wake control activation method

Abstract

The invention relates to a method for controlling yaw offsets of a plurality of wind turbines. The method uses a decision function which generates an activation parameter for determining whether the yaw offset control of a particular wind turbine should be enabled or disabled. The decision function depends on two or more variables, including a wind direction variable indicating the wind direction of the particular wind turbine and a wind variation variable defining at least a wind variation range within which the yaw offset control is disabled or enabled. Based on the decision function, it is determined whether a yaw offset should be added to the current yaw setting of the particular wind turbine.

Description

Technical Field

[0001] This invention relates to the control of wind farms comprising multiple wind turbines, and more particularly to a method for dealing with wake effects. Background Technology

[0002] Wake losses in wind farms can lead to power generation losses.

[0003] EP 2 063 108 A2 discloses a method for increasing the power production of a wind farm during conditions where the wake effect created by an upstream turbine affects the power production of a downstream turbine. Minimizing the wake effect created by the upstream turbine on the downstream turbine increases the net power produced by both the upstream and downstream turbines. Implementations of an algorithm for determining controller settings for one or more upstream turbines to increase the total energy capture of the turbines in the wind farm are also disclosed. The algorithm further reduces fatigue loads on the downstream turbine by reducing the turbulence created by the wake effect of the upstream turbine.

[0004] There is still a need to improve the capabilities of wake control methods to reliably improve the compensation for wake losses. Summary of the Invention

[0005] One object of the present invention is to provide an improved method for limiting power production losses due to wake effects.

[0006] In a first aspect of the invention, a method for controlling the yaw offset of a plurality of wind turbines is provided, wherein the method includes:

[0007] - Provide a decision function, which is configured to provide activation parameters for a specific wind turbine among the plurality of wind turbines based on two or more variables, wherein the two or more variables include:

[0008] - Wind direction variable, which indicates the wind direction for the specific wind turbine, and

[0009] - Wind variation variables, wherein the wind variation variables at least define the wind variation range with yaw offset control disabled and / or the wind variation range with yaw offset control enabled, and

[0010] - Enable or disable yaw offset control for the specific wind turbine based on the activation parameter, wherein the enabled yaw offset control provides a yaw offset relative to the default yaw setting.

[0011] Advantageously, this decision function determines which wind turbines should enable or disable yaw offset control. Since this decision is based on the range of wind variation, a given energy production is more likely to be achieved as long as the actual wind variation falls within that range. In other words, because there is a given probability that a certain wind condition (such as wind direction) will fall within the range of wind variation, there is a corresponding (high) probability of achieving a given energy production as long as the wind conditions are within that range.

[0012] Therefore, this method can increase the likelihood that control actions actually improve production without worsening power production in an attempt to partially compensate for power production losses caused by wake.

[0013] Decision functions, for example, provide information via activation parameters that enables or disables yaw offset control for a particular wind turbine based on the variables of the function.

[0014] Wind direction variables indicate the direction of wind near a specific wind turbine. Wind direction can be the average of wind directions measured within a given time window (such as mean absolute wind direction).

[0015] The wind variation variable can define the range of variables for which offset control is disabled, such as the wind direction range for which offset control is disabled regardless of the values ​​of other variables. Additionally, the wind variation variable can define the range of variables for which offset control is enabled or disabled based on the values ​​of other variables in the decision function.

[0016] Wind variation can be defined as the standard deviation of wind variables, such as the standard deviation of wind direction or wind turbulence. Therefore, the range of wind variation can be defined as the level of the standard deviation.

[0017] Yaw offset control provides an offset yaw angle to the default yaw setting (i.e., the yaw setting typically applied to maximize the airflow to the rotor plane).

[0018] According to one embodiment, the wind variation variable includes one or both of the following: a wind direction variation variable, which indicates the level of change of wind direction over time; and a wind turbulence variation variable, which indicates the level of change of wind turbulence.

[0019] Advantageously, by determining the activation parameters based on the level of wind direction change, yaw offset control can only be activated if the wind direction change is low enough to make it more likely to introduce yaw offset control to improve power production.

[0020] According to one embodiment, the activation parameter provides information defining whether yaw offset control should be disabled and / or enabled.

[0021] According to one embodiment, the decision function is determined based on a comparison of simulated energy production of the plurality of wind turbines when yaw offset control is enabled and disabled for one or more of the plurality of wind turbines, respectively.

[0022] According to one embodiment, the decision function is determined and / or updated based on a comparison of the actual energy production of the plurality of wind turbines obtained when yaw offset control is enabled and disabled for one or more of the plurality of wind turbines, respectively.

[0023] Advantageously, updating the decision function based on actual data makes the decision to enable or disable yaw offset control based on experience, and therefore more accurate relative to the energy production gained.

[0024] According to one embodiment, the yaw offset is scaled according to weights provided by a decision function or activation parameters.

[0025] Advantageously, instead of simply enabling or disabling yaw offset, the level of yaw offset can be scaled based on the value of the variable in the decision function.

[0026] According to one embodiment, the variables of the decision function further include: wind shear variables; nacelle orientation variables of a specific wind turbine; nacelle orientation variables of adjacent wind turbines of a specific wind turbine; and wind turbulence variables of adjacent wind turbines of a specific wind turbine.

[0027] According to one embodiment, the method includes providing a plurality of decision functions arranged to provide a plurality of activation parameters for a plurality of specific wind turbines based on two or more variables.

[0028] Advantageously, a decision function is provided for each wind turbine.

[0029] A second aspect of the invention relates to a wind turbine controller unit arranged for controlling the yaw offset of one or more wind turbines, the wind turbine controller unit comprising:

[0030] - A decision function, which is configured to provide activation parameters for a specific wind turbine among the plurality of wind turbines based on two or more variables, wherein the two or more variables include:

[0031] - Wind direction variable, which indicates the wind direction for the specific wind turbine, and

[0032] - Wind variation variables, wherein the wind variation variables at least define the wind variation range with yaw offset control disabled and / or the wind variation range with yaw offset control enabled.

[0033] The activation parameter is provided to enable or disable yaw offset control for the specific wind turbine, wherein the enabled yaw offset control provides a yaw offset relative to the default yaw setting.

[0034] A third aspect of the invention relates to a computer program product comprising software code adapted to control a wind turbine when executed on a data processing system, the computer program product being adapted to perform the method of the first aspect.

[0035] In general, various aspects and embodiments of the present invention can be combined and coupled in any possible manner within the scope of the present invention. These and other aspects, features, and / or advantages of the present invention will become apparent from the embodiments described below and will be elucidated with reference to the embodiments described below. Attached Figure Description

[0036] Embodiments of the invention will be described by way of example only with reference to the accompanying drawings, wherein:

[0037] Figure 1A This illustrates a wind farm that includes multiple wind turbines and a wind farm controller.

[0038] Figure 1B This shows the relative positions of the wind turbines in the wind farm.

[0039] Figure 2A The diagram shows a yaw control system configured to control the yaw angle of a wind turbine.

[0040] Figure 2B An example configuration of a yaw offset controller for determining the yaw offset θ of a particular wind turbine is shown.

[0041] Figure 3A This illustrates a possible way to implement the decision function of a yaw controller based on a curve spanned by two variables in a 2D space, and...

[0042] Figure 3B This paper illustrates a possible way to implement the decision function of a yaw controller based on curves spanning three variables in a 3D space. Detailed Implementation

[0043] Figure 1A A wind farm 100 comprising multiple wind turbines 101 is shown.

[0044] The wind farm can be connected to the power grid (not shown) to supply the electricity generated by the wind turbine 101 to the power grid.

[0045] In the example shown, the wind turbines of wind farm 100 are controlled by a central wind farm controller 110. The wind farm controller 110 is configured to control the power generation from wind turbines 101 according to a wind farm reference Pref, which defines the desired power to be supplied from wind farm 100 to the grid. Furthermore, the central controller is configured to assign power setpoints Pset to the wind turbines, i.e., to assign a separate power setpoint to each wind turbine 101, which sets the desired power production of each individual wind turbine. The power setpoints Pset can be determined by the wind farm controller 110 based on the wind farm reference Pref, such that the sum of the power setpoints Pset corresponds to the wind farm reference Pref.

[0046] The wind turbine 101 includes a tower and a rotor with at least one rotor blade (such as three blades). The rotor is connected to a nacelle mounted on top of the tower and adapted to drive a generator located within the nacelle. The rotor can rotate in the presence of wind. The rotational energy of the rotor blades caused by the wind is transferred to the generator via a shaft. Thus, the wind turbine is able to convert the kinetic energy of the wind into mechanical energy by means of the rotor blades, and subsequently into electrical energy by means of the generator. The wind turbine may also include a power converter for converting alternating current (AC) from the generator to direct current (DC) and a power inverter for converting DC to AC for injection into the power grid.

[0047] The generator of the wind turbine 101 can be controlled to produce power corresponding to a power setpoint Pset provided by the wind farm controller 110. For the wind turbine, the output power can be adjusted according to the power setpoint by adjusting the pitch of the rotor blades or by controlling the power converter to adjust the power production.

[0048] Figure 1B The relative positions of wind turbines 101 in a basic schematic diagram of a wind farm 100 as seen from above are shown. In the configuration of the wind farm 100 shown on the left, the rotor planes 121 of all wind turbines are perpendicular to the wind direction 122 to maximize wind energy capture. However, the rotor of the upstream wind turbine 101a generates a wake in the form of a wind field 123 with reduced wind speeds, which affects the downstream wind turbines 101b and 101c. This reduction in wind speed in the shadow of the upstream wind turbine is called the wake effect.

[0049] In the configuration of the wind farm 100 shown on the right, the rotor plane 121 of the upstream wind turbine 101d has been rotated to blow air, i.e., yawed air, so that the normal of the rotor plane deviates from the wind direction 122 by a certain angle θ, which depends on or corresponds to the nacelle direction 131.

[0050] The orientation of the nacelle, or equivalently the orientation of the rotor plane normal relative to a fixed direction (such as geographic north), is referred to as nacelle orientation 131, which indicates the yaw angle of a particular wind turbine 101.

[0051] As the rotor plane 121 of the upstream wind turbine 101d rotates and discharges air, the downstream wind field 123 is guided away from the wind direction. Therefore, by providing yaw offset control to the wind turbine 101, the downstream wind field 123 can be guided according to the yaw offset θ of the upstream wind turbine, so that the downstream wind turbines 101e and 101f are less affected by the wake effect. The directional angle of the downstream wind field 123 obviously depends on the wind direction 122, but also on the wind speed, wind shear (i.e., the distribution of different wind speeds on the rotor plane), wind turbulence, and other wind characteristics.

[0052] Therefore, under this ideal condition with a fixed wind direction 122 and a fixed wind speed, the nacelle orientation 131 of all wind turbines 101 can be determined, thereby optimizing wake compensation for the wind farm 100.

[0053] Therefore, given predictable wind conditions including predictable wind speed and direction, and a known nacelle orientation 131, the yaw offset angle θ for each turbine that optimizes power production at least relative to the wake effect can be determined.

[0054] However, such wind conditions are only predictable with a certain probability. Therefore, when the statistical variation of wind parameters is not taken into account, the wake control of wind farm 100 implemented to optimize power production is at risk of failure.

[0055] For example, under wind direction 122, the redirected wind field 123 of the upstream wind turbine 101a can pass through the row of downstream wind turbines 101. However, if the wind direction changes from direction 122 to wind direction 122a, the redirected wind field 123 can change into another redirected wind field 123a, which may affect one of the downstream wind turbines 101e with reduced wind speed and possible wind turbulence. This shows that under one wind condition, yaw offset control, i.e., wake control, can provide wake compensation for optimized power production, but under another possible wind condition, yaw offset control may even worsen power production compared to the case where yaw offset control is not implemented.

[0056] Yaw offset θ can be defined as the deviation of the nacelle orientation 131 caused by yaw offset from the normal, uncompensated nacelle orientation 131 (e.g., where the rotor plane 121 is perpendicular to the wind direction 122).

[0057] Figure 2AA wind turbine controller is shown, such as a yaw control system 290 arranged to control the yaw angle of a wind turbine 101. The yaw control system 290 includes: a yaw offset controller 291 arranged to provide yaw offset control in terms of the yaw offset angle θ; and a yaw controller 292 arranged to control a yaw mechanism 293 according to a desired nacelle orientation 131, such as an optimal nacelle orientation 131 that ensures the rotor plane is perpendicular to the wind direction 122. The optimal nacelle orientation 131 is obtained from a default yaw setting provided by the yaw controller 292.

[0058] The yaw offset controller 291 is configured to be enabled to provide yaw offset θ based on an activation parameter Px (e.g., a binary parameter Px provided by a binary activation signal), or to be disabled, i.e., to provide no yaw offset θ or to provide zero yaw offset θ. Therefore, the activation parameter Px provides information defining whether the yaw offset controller 291 should generate yaw offset control.

[0059] When the yaw offset controller 291 is enabled, the yaw offset θ is determined and added to the output of the yaw controller 292, so that the default yaw setting is modified by the yaw offset θ.

[0060] Alternatively, instead of a separate yaw offset controller 291, the yaw offset controller 291 can be combined with the yaw controller 292, such that the yaw offset θ can be combined with other control signals of the yaw controller besides the output control signal.

[0061] Figure 2A Also shown is a wind turbine controller unit 200 configured to control the yaw offset θ of one or more wind turbines 101. The wind turbine controller unit 200 includes a decision function 201 configured to provide an activation parameter Px for a particular wind turbine 101a among a plurality of wind turbines 101 based on two or more variables 210.

[0062] Variable 210 includes a wind direction variable Wx that indicates the wind direction for a particular wind turbine. The wind direction variable may be based on wind direction 122 obtained from a central wind sensor such as a weather mast, wind direction 122 obtained from distributed wind sensors such as wind sensors for the individual wind turbines 101, estimated wind direction, etc.

[0063] Variable 210 also includes a wind variation variable ΔWx, which at least defines or relates to the wind variation range with yaw offset control disabled and / or with yaw offset control enabled, either independent of other variables in some ranges or dependent on other variables in other ranges. The range with yaw offset disabled is complementary to the range with yaw offset enabled.

[0064] Wind change variables can include wind direction change ΔWDx, which indicates the level of wind direction change over time.

[0065] Alternatively or additionally, wind variation variables may include wind turbulence variation variables ΔWTx, which indicate the level of variation in wind turbulence.

[0066] The wind direction change variable ΔWDx can be determined based on wind direction measurements from individual wind turbines or via a central wind direction measurement. The measurements used to determine ΔWDx can be the most recent measurements obtained within a time period prior to enabling or disabling yaw offset control. This time period can be a predetermined period, such as the past 100 minutes prior to enabling or disabling yaw offset control. In this way, it can be ensured that yaw offset control is only enabled if the wind direction is sufficiently stable, and has been sufficiently stable within the time period prior to invoking yaw offset control.

[0067] The wind direction change variable ΔWDx can be determined as the standard deviation of the wind direction measurement results, as the range covering the maximum and minimum wind directions obtained within a given time period, as the range covering the wind directions that occur at frequencies above a given threshold, or by other methods that reflect changes in wind direction 122.

[0068] Similarly, the wind turbulence variation variable ΔWTx can be determined based on wind turbulence measurements from individual wind turbines or via a central wind turbulence measurement. The measurements used to determine the wind turbulence variation variable ΔWTx can be the most recent measurements obtained over a time period in a manner similar to those used for the wind direction variation variable. The time periods used for the wind direction variation variable and the wind turbulence variation variable can be of the same length or different lengths.

[0069] The wind turbulence variation variable ΔWDx can be determined as the standard deviation of wind turbulence measurements, as the range covering the maximum and minimum turbulence values ​​or such values ​​occurring at frequencies above a given threshold, or by other methods that reflect changes in wind turbulence.

[0070] Other optional variables 210 that may be used to determine or provide activation parameters include wind shear variables indicating the variation of wind speed on rotor plane 121, nacelle orientation variables for a particular wind turbine (such as nacelle orientation 131), nacelle orientation variables for adjacent wind turbines of a particular wind turbine (such as nacelle orientation 131 of wind turbines other than a particular wind turbine 101a), wind turbulence variables indicating the actual wind turbulence of a particular wind turbine 101a, and wind turbulence variables indicating the actual wind turbulence of adjacent wind turbines or one or more other wind turbines 101 other than a particular wind turbine 101a.

[0071] The activation parameter Px is provided to enable or disable yaw offset control for a specific wind turbine, that is, to enable or disable the generation of yaw offset θ relative to the default yaw setting.

[0072] For example, the wind turbine controller unit 200 may include a control function 202 configured to enable or disable yaw offset control for a specific wind turbine 101a based on an activation parameter Px. Alternatively, the control function 202 may be included or otherwise provided by the yaw offset controller 291 to invoke a yaw offset θ.

[0073] The yaw offset θ can be scaled according to weights (e.g., weights between 0 and 1 provided by decision function 201 or by activation parameter Px). For example, activation parameter Px can be a value between 0 and 1, where 0 disables yaw offset control, and where values ​​above 0 and at most 1 scale the yaw offset θ determined by yaw offset controller 201. The weights or values ​​of activation parameter Px depend on variable 210 for determination.

[0074] Figure 2B An example configuration of the yaw offset controller 291 is shown, wherein a lookup table is used to determine the yaw offset θ of a specific wind turbine 101a based on the wind direction Wx and wind speed for the wind turbine. For example, for wind speeds in the range of 10-15 m / s, the yaw offset values ​​θ in the intervals 0-10; 10-20; 20-30; and 30-40 are 20°, 15°, 10°, and 0°, respectively. Therefore, each wind turbine 101 can have its own individually configured yaw offset controller 291 with a lookup table, which can be based on, for example... Figure 1B The wake analysis shown is determined for each wind turbine.

[0075] Figure 3A The diagram illustrates possible configurations of the decision function 300, where the function, represented as a piecewise linear curve 301, depends on two variables 210: the wind direction variable Wx and the wind direction change variable ΔWDx. ​​That is, based on these two variables 210 (typically n variables), it can be determined whether a coordinate point is inside or outside the envelope of curve 301, where one or more curves are typically defined in an n-dimensional space of variables 210.

[0076] Figure 3B The following example is illustrated: where the decision function 300 depends on three variables: wind direction variable Wx, wind direction change variable ΔWDx, and wind turbulence change variable ΔWTx. In this case, the function is represented by a 3D surface 301.

[0077] In these examples, as well as other configurations of the decision function 300 based on curve 301, the activation parameter Px depends on the position of variable 210 within or outside the space of function 301. Therefore, if variable 210 is within the outer space of function 301, the activation parameter Px is determined, for example, by setting Px to zero to disable yaw offset control.

[0078] In other examples, the decision function can be configured to provide a lookup table, mathematical function, or algorithm for the activation parameter Px.

[0079] Figure 3A This illustrates how yaw offset can be scaled using weights provided by a decision function. For example, as shown, decision function 300 can define different regions 302, 303 within function 301, or it can define two or more functions 301, 301a, such that the value of the activation parameter Px depends on the magnitude of variable 210. In this example, Px can be provided by a binary activation signal, and then the yaw offset value θ can be scaled based on the value of the activation parameter Px or other weight values ​​provided by decision function 300. Although not explicitly shown... Figure 3B As shown, however, decision functions 300 with three or more dimensions, along with lookup tables and other configurations, can be similarly configured to provide weight values ​​for scaling the yaw offset θ.

[0080] The decision function can be determined from simulations of energy production from a wind turbine plant. For different wind directions Wx and wind speeds, the yaw offset θ is determined by the yaw offset controller 291, for example, according to... Figure 2B The lookup table is provided. Based on the yaw offset θ of each individual wind turbine, wind farm energy production is compared with and without yaw offset control for one or more of the multiple wind turbines. The comparison is determined for different values ​​of variable 210 and permutations of wind turbines with and without yaw offset control, in order to define the boundaries of decision function 300 with respect to different scaling weights for enabling and disabling yaw offset control, and possibly with respect to the enabled yaw offset θ.

[0081] Alternatively, the decision function can be determined based on an optimization function that, according to variable 210 and wind speed, determines which mode in the enabled and disabled yaw offset control settings optimizes the energy production of multiple wind turbines.

[0082] Alternatively or additionally, the decision function can be determined and / or updated based on measurements of energy production, such as comparing the actual energy production of multiple wind turbines with yaw offset control enabled and disabled for one or more of multiple wind turbines, and across different ranges of variable 210 and wind speed. For example, during normal operation of a wind farm, the modes of enabling and disabling yaw offset control settings can be permuted and combined to search for the most favorable modes for enabling and disabling yaw offset control for multiple wind turbines based on the actual values ​​of variable 210 and wind speed.

[0083] The wind turbine controller unit 200 may be comprised of a wind turbine controller associated with each wind turbine 101 and arranged to control a particular wind turbine. The wind turbine controller includes a yaw control system 290 and the wind turbine controller unit 200.

[0084] Alternatively, the wind turbine controller unit 200 may be included by the wind farm controller 110. In this case, the wind turbine controller unit 200 is arranged to control multiple wind turbines, i.e., arranged to provide activation parameters Px to each wind turbine or each yaw offset controller 291. In principle, the yaw offset controllers 291 can be distributed, for example, distributed within the wind farm controller. However, advantageously, the yaw offset controllers 291 are included by each wind turbine 101. In this case, the wind farm controller 110 is configured with a communication function for sending activation parameters Ps, for example as yaw offset activation signals, to one or more of the multiple wind turbines to individually enable or disable yaw offset control.

[0085] Therefore, the wind turbine controller unit 200 can be included in a wind turbine controller, a wind farm controller 110, or a SCADA system.

Claims

1. A method for controlling the yaw offset (θ) of a plurality of wind turbines (101), the method comprising: - Provide a decision function (300) configured to provide activation parameters (Px) for a specific wind turbine (101a) among the plurality of wind turbines based on two or more variables (210), wherein the two or more variables (210) include: - Wind direction variable (Wx), which indicates the wind direction for the specific wind turbine, and - Wind variation variable (ΔWx), which at least defines the wind variation range with yaw offset control disabled and / or the wind variation range with yaw offset control enabled. - Enable or disable yaw offset control for the specific wind turbine based on the activation parameters, wherein the enabled yaw offset control provides a yaw offset (θ) relative to the default yaw setting, and The wind direction change variable is determined from the most recent measurement obtained within a period of time before the yaw offset control is enabled or disabled.

2. The method according to claim 1, wherein, The wind variation variable (ΔWx) includes one or both of the following: - Wind direction change variable (ΔWDx), which indicates the level of change in wind direction over time, and - Wind turbulence variation variable (ΔWTx), which indicates the level of change in wind turbulence.

3. The method according to claim 1 or 2, wherein, The activation parameters provide information defining whether yaw offset control should be disabled and / or enabled.

4. The method according to claim 1 or 2, wherein, The decision function has been determined based on a comparison of the simulated energy production of the plurality of wind turbines with yaw offset control enabled and disabled for one or more of the plurality of wind turbines, respectively.

5. The method according to claim 1 or 2, wherein, The decision function has been determined and / or updated based on a comparison of the actual energy production of the plurality of wind turbines obtained when yaw offset control is enabled and disabled for one or more of the plurality of wind turbines, respectively.

6. The method according to claim 1 or 2, wherein, The yaw offset is scaled according to the decision function or the weights provided by the activation parameter (Px).

7. The method according to claim 1 or 2, wherein, The variables of the decision function also include: wind shear variables; nacelle orientation variables of the specific wind turbine; nacelle orientation variables of the adjacent wind turbines of the specific wind turbine; and wind turbulence variables of the adjacent wind turbines of the specific wind turbine.

8. The method according to claim 1 or 2, comprising: - Provide multiple decision functions, which are arranged to provide multiple activation parameters for multiple specific wind turbines based on the two or more variables.

9. A wind turbine controller unit (200) arranged for controlling the yaw offset of one or more wind turbines (101), the wind turbine controller unit comprising: - A decision function, which is configured to provide activation parameters (Px) for a specific wind turbine among the plurality of wind turbines based on two or more variables (210), wherein the two or more variables include: - Wind direction variable (Wx), which indicates the wind direction for the specific wind turbine, and - Wind variation variable (ΔWx), which at least defines the wind variation range with yaw offset control disabled and / or the wind variation range with yaw offset control enabled. The activation parameter is provided to enable or disable yaw offset control for the specific wind turbine, wherein enabled yaw offset control provides a yaw offset relative to the default yaw setting, and The wind direction change variable is determined from the most recent measurement obtained within a period of time before the yaw offset control is enabled or disabled.

10. A computer program product comprising software code adapted to control a wind turbine when executed on a data processing system, said computer program product being adapted to perform the method of any one of claims 1-8.

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