阅读说明：本技术 经由变桨施加风轮机偏航力矩 (Applying wind turbine yaw moment via pitch ) 是由 A·伊德 J·X·V·内托 K·H·瑟恩森 于 2018-12-04 设计创作，主要内容包括：提出了一种用于控制风力涡轮机100上的转子102的方法310,其中,所述转子包括一个或多个叶片103,并且其中所述风力涡轮机包括变桨系统,所述方法包括：在静止或空转运行状态下运行312所述转子,确定或接收314一个或多个控制参数,其中控制参数使得能够确定一个或多个偏航参数能够被描述为所述一个或多个控制参数的函数,其中所述一个或多个偏航参数包括以下一项或多项：偏航部段的偏航角速度,所述偏航部段的偏航角加速度,和/或所述偏航部段施加在所述风力涡轮机的其余部分上的偏航力矩,以及通过所述变桨系统基于所述一个或多个控制参数使所述转子100的一个或多个叶片103变桨316。(A method 310 for controlling a rotor 102 on a wind turbine 100 is proposed, wherein the rotor comprises one or more blades 103, and wherein the wind turbine comprises a pitch system, the method comprising: operating 312 the rotor in a stationary or idling operating state, determining or receiving 314 one or more control parameters, wherein the control parameters enable determination of one or more yaw parameters that can be described as a function of the one or more control parameters, wherein the one or more yaw parameters comprise one or more of: a yaw rate of a yaw section, a yaw acceleration of the yaw section, and/or a yaw moment exerted by the yaw section on the rest of the wind turbine, and pitching 316 one or more blades 103 of the rotor 100 by the pitch system based on the one or more control parameters.)

1. A method (310) for controlling a rotor (102) on a wind turbine (100), wherein the rotor comprises one or more blades (103), and wherein the wind turbine comprises:

-a pitch system for the pitch of the wind turbine,

the method comprises the following steps:

-operating (312) the rotor in a stationary or idle operating state,

-determining or receiving (314) one or more control parameters, wherein one or more yaw parameters can be described as a function of the one or more control parameters, wherein the one or more yaw parameters comprise one or more of:

i. the yaw rate of the yaw section,

yaw angular acceleration of the yaw section,

and/or

The yaw section exerts a yaw moment on the rest of the wind turbine, an

-pitching (316), by the pitch system, one or more blades (103) of the rotor (100) based on the one or more control parameters.

2. A method (310) for controlling a rotor on a wind turbine (100) according to any of the preceding claims, wherein said pitching is performed in order to increase or decrease an aerodynamically induced yaw moment exerted by aerodynamic forces on said yawing section.

3. A method (310) for controlling a rotor on a wind turbine (100) according to any of the preceding claims, wherein the wind turbine comprises:

-a yaw system for yawing a yawing section of the wind turbine.

4. A method (310) for controlling a rotor on a wind turbine (100) according to claim 3, wherein the method further comprises:

-detecting (411) a fault in the yawing system.

5. A method (310) for controlling a rotor on a wind turbine (100) according to any of the preceding claims, wherein said pitching is performed such that the resulting change in aerodynamic force on the one or more blades contributes to a reduction of the one or more yaw parameters.

6. A method (310) for controlling a rotor on a wind turbine according to any of the preceding claims, wherein the wind turbine is a single rotor wind turbine (100).

7. A method (310) for controlling a rotor on a wind turbine according to any of the preceding claims, wherein the wind turbine is a multi-rotor wind turbine (1).

8. The method (310) for controlling a rotor on a wind turbine according to claim 7, wherein pitching one or more blades comprises:

-pitching (416) a subset of one or more blades of the rotor to a greater extent than the remaining blades of the rotor.

9. The method (310) for controlling a rotor on a wind turbine according to claim 8, wherein pitching a subset of the one or more blades comprises:

pitching 1 and only 1 blade on a 3-blade rotor or a 2-blade rotor,

or

Pitching 2 and only 2 blades on a 3-blade rotor.

10. A method (310) for controlling a rotor on a wind turbine according to any of the preceding claims, wherein pitching the one or more blades comprises:

pitching in an azimuth-dependent manner.

11. The method (310) for controlling the rotor on a wind turbine according to claim 10, wherein pitching one or more blades in an azimuth-dependent manner comprises: pitching one or more blades on a rotor such that a moment from drag on the one or more blades generates a net non-zero moment about an axis parallel to a yaw axis and intersecting an axis of rotation of the rotor.

12. The method (310) for controlling a rotor on a wind turbine according to any of claims 7-9 and any of claims 10-11, wherein pitching one or more blades in an azimuth-dependent manner comprises: pitching one or more blades on a rotor such that drag on the one or more blades is greater in a first azimuthal range relative to drag in a second azimuthal range, wherein the first azimuthal range is further from the yaw axis than the second azimuthal range.

13. A control system arranged to:

-receiving one or more control parameters, wherein one or more yaw parameters can be described as a function of the one or more control parameters, wherein the one or more yaw parameters comprise one or more of:

i. yaw angular velocity (ω) of the yaw section,

yaw angular acceleration (a) of the yaw section,

and/or

A yaw moment (M) exerted by the yaw section on the rest of the wind turbine, and

-determining and outputting one or more pitch angle set point values based on control parameters of one or more blades (103) of the rotor (102).

14. A wind turbine (100) comprising a control system according to claim 13.

15. A computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out the steps of any of claims 1-12.

Technical Field

The present invention relates to a method for controlling a rotor on a wind turbine, more particularly a method for pitching one or more blades on a rotor based on a control or yaw parameter, and a corresponding control system, wind turbine and computer program product.

Background

When the wind turbine rotor is in an idling or stationary operating state (such as in a non-power producing state and neither started nor stopped), forces external to the wind turbine (e.g., aerodynamic forces) may exert a yawing moment on the wind turbine. This yaw moment may lead to damaging effects on the wind turbine.

Thus, it is advantageous to be able to mitigate these damaging effects, and it is particularly advantageous to be able to reduce or eliminate these damaging effects, and for example to be able to increase the lifetime of the wind turbine.

Disclosure of Invention

It may be seen as an object of the present invention to provide a method for controlling a rotor on a wind turbine that solves the above mentioned problems of the prior art caused by forces external to the wind turbine, such as aerodynamic forces, which may exert a yawing moment on the wind turbine, which yawing moment causes a damaging effect on the wind turbine.

The above object is intended to be achieved in a first aspect of the present invention by providing a method for controlling a rotor on a wind turbine, wherein the rotor comprises one or more blades, and wherein the wind turbine comprises:

a pitch system, such as a pitch system for pitching one or more blades of the rotor,

the method comprises the following steps:

-operating the rotor in a stationary or idle operating state,

-determining or receiving one or more control parameters, wherein one or more yaw parameters can be described as a function of the one or more control parameters, wherein the one or more yaw parameters comprise one or more of:

i. a yaw rate (ω) of a yaw section, such as a yaw rate (ω) of the yaw section relative to a remainder of the wind turbine,

a yaw angular acceleration (a) of the yaw section, such as a yaw acceleration (a) of the yaw section relative to the rest of the wind turbine,

and/or

A yaw moment (M) exerted by the yaw section on the rest of the wind turbine, and

-pitching, by the pitch system, one or more blades of the rotor based on the one or more control parameters.

The invention is particularly, but not exclusively, advantageous for obtaining a method in which the control parameter may be used as an input to the pitch, which may enable the pitch to be used to generate a force for maintaining or changing the value of the control parameter (such as in a closed loop control system). For example, where the value of the control parameter is optimal, pitch may be used to generate a force for maintaining the value of the control parameter. In another example, in the event that the value of the control parameter is not ideal or optimal, the pitch may be used to generate a force for changing the value of the control parameter towards a more optimal value. This, in turn, may, for example, reduce or eliminate the need for a yaw system and/or may enable yaw to be achieved during a yaw system failure.

The invention may be particularly relevant in case of a malfunction in the yawing system, such as a malfunction in one or more components achieving a predetermined friction level. The yaw system may include a slip feature to mitigate extreme loads, and there may be some threshold or "friction level" during normal operation. This "level of friction" may be reduced when the yaw system fails (such as when a component implementing the slip feature fails). When the wind turbine is in an idling or stationary operating state (such as due to a malfunction of the yaw system), for example, turbulence and/or changes in wind direction may cause the yaw section to yaw (which may slip during high yaw loads). However, for example, in case of a malfunction of the yaw system, the yaw slip moment threshold may be lowered, which may result in a higher (such as too high) yaw rate, which may further overload the yaw system. In an embodiment according to the invention, pitching may be performed based on the control parameter to counteract yaw and reduce yaw angular velocity. As an example, in a three-blade rotor of a multi-rotor wind turbine, this may be done by pitching two blades, thereby increasing the drag to generate a yaw moment on the yaw section about the yaw axis for slowing down an excessively high yaw angular velocity.

In embodiments, a "wind turbine" may be a horizontal (rotor) axis wind turbine and/or an upwind wind turbine.

The "rotor" is understood as generally understood in the art. It will be appreciated that the wind turbine may have only a single rotor (in a single rotor wind turbine) or a plurality of rotors (in a multi-rotor wind turbine). Reference to a "rotor" is meant to refer to a rotor (such as one rotor in a single rotor wind turbine or one rotor in a multi-rotor wind turbine). For a multi-rotor wind turbine, it should be understood that one rotor is in an idling or stationary operational state does not mean that the remaining rotors are also in an idling or stationary operational state. The present invention contemplates having one rotor in a multi-rotor wind turbine in an idling or stationary operating condition and having the other rotor not in an idling or stationary operating condition (such as the other rotor being in normal power producing operation).

"stationary" is understood as it is commonly understood in the art and can be understood to describe the following operating states of the rotor: wherein the rotor (such as the rotor and corresponding generator) does not produce electricity (such as does not deliver electricity to the grid), and wherein the rotor is braked (such as wherein rotation about the rotor axis is maintained at zero angular velocity).

"free-wheeling" is understood as it is commonly understood in the art and can be understood to describe the following operating states of the rotor: wherein the rotor (such as the rotor and corresponding generator) does not produce electricity (such as does not deliver electricity to the grid), and wherein the rotor is allowed to rotate freely. For example, the blades may or may not rotate, but the rotor (such as the rotor and corresponding generator) does not deliver power to the grid.

"determining or receiving (one or more control parameters)" may be understood as: the method may include determining (such as, for example, obtaining one or more input parameters by sensing, and then converting those parameters into one or more control parameters) or simply receiving one or more control parameters (such as simply receiving one or more control parameters from an associated entity).

"one or more control parameters" are understood to relate to one or more yaw parameters in a manner that allows the yaw parameters to be described as a function of the one or more control parameters. More specifically, a set of one or more control parameters is correlated exactly to a set of one or more yaw parameters. This is advantageous for example for enabling closed loop control of the pitch based on the control parameters and thereby controlling one or more yaw parameters (with or without knowledge of the value of the yaw parameters). In one embodiment, the control parameters enable determination of absolute values (such as in units according to the international system of units (SI)) of one or more yaw parameters. In another embodiment, the one or more control parameters comprise or are the same as the one or more yaw parameters.

A "yawing section" is understood to be a part of a wind turbine which can be yawed relative to the rest of the wind turbine. The yaw axis may be orthogonal to the rotor axis (for a horizontal axis wind turbine). "yaw" is understood as commonly understood in the art, such as rotation of the rotor axis about a vertical axis (for a horizontal axis wind turbine). In an embodiment, a "yaw section" may comprise a rotor and a nacelle. In an embodiment, the remainder of the wind turbine may comprise a tower.

"yaw moment" is generally understood to be a moment of yaw force (such as a torque). The expression "exerted by the yawing section on the remainder of the wind turbine" means that the yawing section may exert a moment on the remainder of the wind turbine (or vice versa) about the yaw axis. This may be independent of whether yaw is present (i.e., the yaw rate may be zero or non-zero). For example: if the yaw is fixed (braked), there is a yaw angular velocity and a yaw angular acceleration of zero in the yaw bearing, but there may or may not be a yaw moment exerted on the rest of the wind turbine, such as the tower. It may be added that in practice the tower may have a non-zero torsional flexibility, and thus even if the yaw system is braked and does not slip, the yaw rate may not be zero and a yaw acceleration may be present in case a yaw moment is applied.

"pitching based on one or more control parameters" may be understood as performing pitching in accordance with one or more control parameters (such as pitching being a function of one or more control parameters).

In one embodiment, a method for controlling a rotor on a wind turbine is proposed, wherein said pitching is performed in order to increase or decrease an aerodynamically induced yaw moment (M) exerted on the yawing section by aerodynamic forces, such as drag_aero-yaw). This may be advantageous because aerodynamic forces (such as drag) acting on the rotor may be increased or decreased via pitching, and a yaw moment may be effectively acting on the yaw section due to these aerodynamic forces. This has the advantage that pitching can be utilised to maintain an optimum value for one or more yaw parameters and/or to improve the value of one or more yaw parameters.

In another embodiment, a method for controlling a rotor on a wind turbine is presented, wherein pitching is performed such that the resulting change in aerodynamic force on the one or more blades contributes to a reduction of the one or more yaw parameters (such as the value of the one or more yaw parameters). This is advantageous for avoiding, via pitching, that one or more yaw parameters become too high and/or that one or more yaw parameters have undesirably high values over a longer period of time.

In a second aspect, the invention relates to a control system (210) (such as a control system comprising a processor, such as a control system comprising a processor and an algorithm), the control system being arranged to:

-receiving one or more control parameters, wherein one or more yaw parameters can be described as a function of the one or more control parameters, wherein the one or more yaw parameters comprise one or more of:

i. a yaw angular velocity (ω) of the yaw section, such as a yaw velocity (ω) of the yaw section relative to a remainder of the wind turbine,

a yaw angular acceleration (a) of the yaw section, such as a yaw acceleration (a) of the yaw section relative to the rest of the wind turbine,

and/or

A yaw moment (M) exerted by the yaw section on the rest of the wind turbine, and

-determining and outputting one or more pitch angle set point values based on control parameters of one or more blades of the rotor.

According to an alternative aspect, the invention relates to a control system, such as a control system comprising or controlling an actuator, adapted to perform the method according to the first aspect.

The control system may be arranged to determine pitch angle set point values and may be implemented in a general purpose controller for the wind turbine or in a control element such as a dedicated pitch controller. In one example, a control system receives one or more control parameters, sets a pitch angle set point value (also referred to as a pitch reference) to a pitch control system, which controls a pitch system, which in turn controls the pitch angle of the blades.

In a third aspect, the invention relates to a wind turbine comprising a control system according to the second aspect. According to an alternative aspect, the invention relates to a wind turbine comprising means adapted to perform the method according to the first aspect, such as said means comprising a control system.

In a fourth aspect, the invention relates to a computer program product comprising instructions for causing a computer to perform the steps according to the first aspect when the program is executed by the computer, such as the computer in the control system according to the second aspect. According to an alternative aspect, the invention relates to a computer readable data carrier having stored thereon the computer program product of the fourth aspect. According to an alternative aspect, the invention relates to a data carrier signal carrying the computer program product of the fourth aspect.

Many of the attendant features will be more readily appreciated as the same becomes better understood by reference to the following detailed description considered in connection with the accompanying drawings. As will be apparent to those skilled in the art, the preferred features may be combined as appropriate and with any of the aspects of the invention.

Drawings

Figure 1 depicts a single rotor wind turbine,

figure 2 depicts a multi-rotor wind turbine,

figure 3 shows a flow chart of a method for controlling a rotor on a wind turbine,

figure 4 shows a flow chart of another method for controlling a rotor on a wind turbine,

figures 5-7 show application examples of embodiments of the present invention,

figure 8 shows a graph of the pitch angle,

figure 9 shows the yaw angle according to the simulation results,

figure 10 shows the yaw rate according to the simulation results,

FIG. 11 shows a schematic diagram illustrating yaw in a multi-rotor wind turbine.

Detailed Description

The present invention will now be explained in further detail. While the invention is susceptible to various modifications and alternative forms, specific embodiments have been disclosed by way of example. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.

In an embodiment of the invention, a method for controlling a rotor on a wind turbine is proposed according to any of the preceding claims, wherein the wind turbine is a single rotor wind turbine, such as wherein the single rotor comprises one or more blades.

Fig. 1 shows a wind turbine 100, which may also be referred to as a Wind Turbine Generator (WTG). The wind turbine in fig. 1 is a single rotor wind turbine comprising a tower 101 and a rotor 102 with at least one rotor blade 103, such as three rotor blades. The rotor is connected to a nacelle 104, which nacelle 104 is mounted on top of the tower 101 and is adapted to drive a generator located inside the nacelle. The rotor 102 is rotatable about a rotor axis 105 under the influence of wind. The rotational energy of the rotor blades 103 caused by the wind is transferred to the generator via the shaft. Thus, the wind turbine 100 is capable of converting kinetic energy of wind into mechanical energy by means of the rotor blades and subsequently into electrical power by means of the generator. The generator may include a power converter for converting AC power of the generator to DC power, and a power inverter for converting the DC power to AC power to be injected into a utility grid. The generator may be controlled to produce power corresponding to the power request. Alternatively, it may be controlled to produce generator torque corresponding to the torque request. The rotor blade 103 may be pitched to alter the aerodynamic properties of the blade, for example, to maximize the absorption of wind energy and to ensure that the rotor blade is not subjected to too much load when strong winds blow.

In an embodiment of the invention, a method for controlling a rotor on a wind turbine is proposed, wherein the wind turbine is a multi-rotor wind turbine, such as wherein the wind turbine comprises a plurality of rotors, and wherein each rotor of said plurality of rotors comprises one or more blades.

In wind turbines, such as single rotor wind turbines or multi-rotor wind turbines (2 or more rotors), turbulence and/or changes in wind direction may cause a yawing section to yaw when the wind turbine is stationary or idling (e.g., due to a failure of the yawing system). However, when there is a fault in the yaw system, for example, the yaw slip moment threshold may be lowered, resulting in excessive yaw or yaw at too high a yaw speed, which may further overload the yaw system. In an embodiment of the invention, the wind turbine pitch system in one or more of the plurality of rotors may counteract this movement and reduce the yaw angular velocity and/or yaw moment by pitching two blades of one of the rotors and thereby increasing the drag to apply a yaw moment to the yawing section.

For multiple rotors (wind turbines), the yaw rate may be high. Accordingly, embodiments of the invention may be particularly relevant for multi-rotor wind turbines, such as for reducing the cost of a yaw system in a multi-rotor wind turbine.

Fig. 2 depicts a wind turbine 1, wherein the wind turbine is a multi-rotor wind turbine comprising:

a support structure 3, said support structure 3 comprising a tower 4 and an arm 5 mounted to the tower 4 at a joint 6,

a plurality of wind turbine modules 2 mounted to the support structure 3, wherein each of the plurality of wind turbine modules comprises a rotor 7.

In the present embodiment, the support structure comprises an arm 5 extending outwardly from the tower 4, each of the plurality of wind turbines being mounted on an end of a respective arm. Furthermore, fig. 1 depicts a nacelle 8 for each wind turbine module. In the wind turbine module 2, kinetic energy of the wind is converted into electrical energy by a power generation system (not shown), as will be readily understood by those skilled in the art of wind turbines. The rotor may be rotating as indicated by the four arrows a in fig. 2. Fig. 2 shows a support structure with two arms, each arm with two wind turbine modules, but other embodiments are conceivable, for example four arms with four wind turbine modules (one wind turbine module per arm), or three arms with six, four and two wind turbine modules (lower, middle and upper arms, respectively).

FIG. 3 shows a flow chart of a method 310 for controlling a rotor on a wind turbine, wherein the rotor comprises one or more blades, and wherein the wind turbine comprises:

a pitch system, such as a pitch system for pitching one or more blades of the rotor,

the method comprises the following steps:

-operating 312 the rotor in a stationary or idle operating state,

-determining or receiving 314 one or more control parameters, wherein one or more yaw parameters can be described as a function of the one or more control parameters, wherein the one or more yaw parameters comprise one or more of:

i. a yaw rate (ω) of a yaw section, such as a yaw rate (ω) of the yaw section relative to a remainder of the wind turbine,

a yaw angular acceleration (a) of the yaw section, such as a yaw acceleration (a) of the yaw section relative to the rest of the wind turbine,

and/or

A yaw moment (M) exerted by the yaw section on the rest of the wind turbine, and

pitching 316 one or more blades of the rotor by the pitch system based on the one or more control parameters.

Arrow 318 indicates that the method may be performed as closed loop control.

Fig. 4 shows a flow diagram of another method 410, which is similar to the method depicted in fig. 3, although with differences including that the method further comprises:

-detecting 411 a fault in the yawing system.

It may be noted that embodiments of the present invention may propose new protection strategies for turbines in yawing systems having fault conditions.

Another difference between the method depicted in fig. 4 and the method depicted in fig. 3 is that: in the method depicted in FIG. 4, pitching one or more blades comprises:

pitching 416 a subset of one or more blades of a rotor (such as a single rotor) to a greater extent than the remaining blades of the rotor (such as pitching 2 and only 2 blades on a 3-blade rotor).

In an embodiment, a method for controlling a wind turbine is presented, wherein pitching a subset of one or more blades comprises:

pitching 1 and only 1 blade on a 3-blade rotor or a 2-blade rotor,

or

Pitching 2 and only 2 blades on a 3-blade rotor.

A possible advantage of pitching only a subset of the blades (such as pitching only one or two blades of a three-blade rotor) is to limit acceleration. In other words, it is avoided that the angular velocity of the rotor becomes too high.

In an embodiment, a method for controlling a rotor on a wind turbine 100 is presented, wherein the wind turbine comprises:

a yaw system for yawing a yawing section of the wind turbine (such as for yawing a yawing section of the wind turbine relative to a remainder of the wind turbine).

It will be appreciated that the yaw system and the pitch system are not the same system.

In an embodiment, a method for controlling a rotor on a wind turbine according to any of the preceding claims is presented, wherein pitching the one or more blades comprises:

pitching in an azimuth-dependent manner, such as periodically pitching in an azimuth-dependent manner, such as to form a non-zero net moment when summing the moment contributions over the entire azimuth range.

"pitching in an azimuth-dependent manner" is understood to mean pitching based on the azimuth of the rotor. For example, pitching may only be performed when the blades are located on one side of the rotor axis relative to the yaw axis (such as distal to the rotor axis relative to the yaw axis). An advantage of pitching in an azimuthally dependent manner is that it enables an increase of the yaw moment and/or it enables (through aerodynamics) to act on a centrally arranged (with respect to the yaw axis) rotor, such as a single rotor with a very large rotor plane, wherein there may be significant differences in wind speed in the rotor plane, resulting in yaw loads.

In an embodiment, a method for controlling a rotor on a wind turbine is presented, wherein azimuthally dependent pitching of one or more blades (such as periodically pitching in an azimuthally dependent manner) comprises pitching one or more blades on the rotor such that a moment from drag on the one or more blades produces a net non-zero moment about an axis parallel to a yaw axis and intersecting the rotational axis of the rotor, such as when integrating the moment from drag on the one or more blades over the entire rotor revolution range, a net non-zero moment about an axis parallel to the yaw axis and intersecting the rotational axis of the rotor. For example, for a displacement of the rotor axis relative to the yaw axis, the moment integrated on the far side relative to the yaw axis is greater than the moment integrated on the near side relative to the yaw axis. This may have the advantage that for a multi-rotor (wind turbine) the non-central rotor is increased even more than the guaranteed value for its non-central position, since the side facing away from the yaw axis has a greater moment than the side facing the yaw axis. Another advantage of this may be that it enables the formation of a yaw moment by a rotor (such as a rotor on a single rotor wind turbine) even if the rotor axis of the rotor intersects the yaw axis.

In an embodiment, a method for controlling a rotor on a wind turbine 100 is presented, such as a rotor in which the wind direction/drag and the vector from the yaw axis to the center of the rotor plane are not parallel, wherein pitching one or more blades in an azimuthally dependent manner (such as periodically pitching one or more blades in an azimuthally dependent manner) comprises pitching one or more blades on the rotor such that the drag on the one or more blades is greater in a first azimuthal range relative to the drag in a second azimuthal range, wherein the first azimuthal range is further away from the yaw axis than the second azimuthal range, such as wherein the first azimuthal range is the furthest half of the rotor plane from the yaw axis and the second azimuthal range is the closest half of the rotor plane to the yaw axis.

In an embodiment, a method for controlling a rotor on a wind turbine 100 is presented, the method comprising predicting one or more future values of a control parameter, and wherein pitching is based on said future values. In an embodiment, a control system is proposed, which is arranged for (or a method is proposed for):

-at a decision time point (t)_dec) Estimating one or more control parameters at a future point in time (t), such as using LIDAR-based wind speed prediction_f) Is determined by the estimated value of (c),

-at a future point in time (t) based on one or more control parameters by a pitch system_f) Pitch (316) one or more blades (103) of the rotor (100).

It can be understood that the future time point (t)_f) Later than the decision time point.

In an embodiment, a control system is proposed, which is arranged for (or a method is proposed for):

-at a decision time point (t)_dec) Estimating future points in time (t), such as using LIDAR-based wind speed prediction_f) Whether one or more control parameters of (a) exceed one or more control parameter thresholds, such as:

i. future point in time (t)_f) Yaw rate (ω) of the yaw section of (c)_f) (such as whether the yaw speed (ω) of the yaw section relative to the rest of the wind turbine) is above a yaw angular speed threshold (ω)_thr)，

And/or:

future time point (t)_f) Exerts a yaw moment (M) on the rest of the wind turbine_f) Whether it is higher than yaw moment threshold (M)_thr)，

-such as when the estimated control parameter value is exceeded, such as when the yaw rate threshold value (ω) is estimated at a future point in time_thr) And the yaw moment threshold value (M)_thr) When any one or more of them are exceeded: pitching one or more blades of the rotor such that aerodynamic forces act on the yaw section, thereby creating a moment about the yaw axis of the wind turbine, in order to reduce the one or more control parameters, such as reducing the future point in time (t;)_f) Yaw rate (ω) of the yaw movement of the wind turbine_f) And/or yaw moment threshold (M)_f)。

It can be understood that the future time point (t)_f) Later than the decision time point.

Fig. 5-7 show application examples of embodiments of the present invention. In each of fig. 5-7, a multi-rotor wind turbine (such as the one depicted in fig. 2) is viewed in a direction along the yaw axis, wherein each rotor has three blades.

FIG. 5 illustrates a multi-rotor wind turbine where wind direction changes or turbulence may cause high yaw loads and cause the turbine to yaw in a yaw fault mode when at rest or idling.

Fig. 6 shows that by pitching 2 blades in one rotor ("rotor 1") from 87 degrees to 65 degrees, drag is increased and yaw motion is slowed down to protect the yaw system (from overheating or further damage).

Fig. 7 shows the pitch blades of the rotor 1 pitching back to the feathered position after the yaw movement has ended.

FIG. 8 shows a graph of simulated pitch angles (as shown in degrees on the y-axis of the graph) for three blades of each of the two rotors in FIGS. 5-7. The legend shows the sensor label "bea 2" in the simulation, which corresponds to the sensor label for each blade in a 3-blade rotor. The sub-figures show (a) all blades in rotor 1 (such as the upper left rotor in fig. 2) at a pitch angle of 87-87-87 degrees and (b) all blades in rotor 2 (such as the upper right rotor in fig. 2) at a pitch angle of 87-87-87 degrees. The upper rows (a) - (b) of the sub-graph correspond to the situation in fig. 5. The sub-figures also show that (c) all blades in rotor 1 (such as the upper left rotor in fig. 2) are at a pitch angle of 87-87-87 degrees, (d) one blade in rotor 2 (such as the upper right rotor in fig. 2) is still at a pitch angle of 87 degrees, but the other two blades are pitched 65 degrees in about 600 seconds. The next rows (c) - (d) of the sub-graph correspond to the situation in fig. 6.

Fig. 9 shows the simulation result in which pitching is performed as shown in fig. 8. Fig. 9 shows the yaw angle [ degrees ] (on the y-axis) as a function of time. The legend shows the sensor label "bea 1" in the simulation, which corresponds to the sensor label of the wind turbine. The graph represents the baseline without pitch being performed (solid curve) and the results with pitch being performed (dashed line). It can be seen that by pitching the change in yaw angle is smoothed out over a longer period of time.

Fig. 10 shows the simulation results corresponding to fig. 9, except that the y-axis in fig. 10 shows the yaw rate rpm. Again, the graph represents the baseline without pitch performed (solid curve) and the results with pitch performed (dashed line). It can be seen that a lower maximum yaw rate can be achieved by pitching.

FIG. 11 shows a schematic diagram illustrating yaw in a multi-rotor wind turbine. More specifically, the schematic diagram shows multi-rotor wind turbine 1101 having first and second rotors 1107 a-b. The control system may be arranged to determine pitch angle set point values and may be implemented in a multi-rotor turbine controller that sends the pitch angle set point values to pitch controller 1 (for first rotor 1107a) and pitch controller 2 (for second rotor 1107b), respectively. Thus, the control system (multi-rotor turbine controller) receives one or more control parameters (and optionally a yaw moment (M or M) exerted by the yaw section on the rest of the wind turbine_yaw) In the pitch angle), setting the pitch anglePoint values or a set of pitch angle set point values (also referred to as a pitch reference) (such as θ for the first rotor 1107a, respectively_Blade1 ^Rotor1，θ_Blade2 ^Rotor1，θ_Blade3 ^Rotor1And θ for the second rotor 1107b_Blade1 ^Rotor2，θ_Blade2 ^Rotor2，θ_Blade3 ^Rotor2}) to a pitch controller 1 and a pitch controller 2 system, respectively, each controlling a pitch system, which in turn controls the pitch angle of the blades.

Although the invention has been described in connection with specific embodiments, it should not be construed as being limited to the examples set forth in any way. The scope of the invention is set forth in the appended claims. In the context of the claims, the term "comprising" or "comprises" does not exclude other possible elements or steps. In addition, references to items such as "a" or "an" should not be construed as excluding a plurality. The use of reference signs in the claims with respect to elements indicated in the figures shall not be construed as limiting the scope of the invention either. Furthermore, individual features mentioned in different claims may be advantageously combined, and the mentioning of these features in different claims does not exclude that a combination of features is not possible and advantageous.