DE102010027229A1 - Method and device for providing a parking angle correction signal for a predetermined rotor blade of a wind turbine - Google Patents

Abstract

The present invention provides a method (900) for providing a pitch correction signal (139) for a predetermined rotor blade (210) from a plurality of rotor blades of a wind turbine (110). The pitch correction signal is provided to change a signal (145) to control an individual pitch for the rotor blade. The method (900) has a step of reading in (910) a rotor blade position signal (120) which represents an angular position (Ω1) of the rotor blade with respect to an axis of rotation (310) of the rotor of the wind turbine and / or reading in a rotational speed (ω) of the rotor blade around the axis of rotation (310). The method (900) further comprises a step of determining (920) the angle of attack correction signal (139) for the predetermined rotor blade of the wind power plant using a relationship between an angle position and a angle of attack correction factor stored in a memory (137), wherein the angle of attack -Correction signal represents the angle of attack correction factor which, when used, causes a correction of the signal (145) for controlling the individual angle of attack for the predetermined rotor blade, so that an effect of a moment (M1) on the predetermined rotor blade an effect of a moment (M2, M3 ) is adjusted to at least one other rotor blade of the wind power plant and the determination is carried out using the read rotor blade position signal and / or the read rotational speed.

Description

The present invention relates to a method and an apparatus for providing a pitch correction signal for a predetermined rotor blade of a plurality of rotor blades of a wind turbine according to the independent claims.

In wind turbines with a horizontal axis and at least two rotor blades, synchronously adjusting the blade angle, the speed above the rated wind speed is controlled so that by changing the angle of attack (also referred to as the pitch angle) of the aerodynamic lift and thus the drive torque is changed in such a way that a reduction of the buoyancy force responsible for the drive torque can be achieved and thus the system can be maintained in the range of rated speed. At wind speeds above the shutdown speed, this blade pitch mechanism is also used as a brake by putting the blades nose-to-wind so that the rotor no longer delivers any significant drive torque. The rotor blades can then be used as aerodynamic brakes by being placed completely in the Windanströmrichtung (flag position) or the angle of attack is increased so much that the flow leaves (stable). Collective pitch control (CPC) results in pitching and yawing moments on the nacelle due to asymmetric aerodynamic loads. The asymmetric loads arise z. For example, by wind shear in the vertical direction (boundary layers), yaw angle errors, gusts and turbulence, impoundment of the flow at the tower, etc. Lately, a new approach for the control of three-wing wind turbines is increasingly examined, which in addition to the collective pitch angle an individual pitch angle calculated the individual rotor blades. The individual pitch control (IPC) allows a reduction in the asymmetrical loads transmitted to the hub via the nacelle. For this purpose, the bending moments acting on the individual rotor blade roots are measured and the individual blade adjustment necessary for the reduction of the yawing and pitching moments is calculated. The pitch angles calculated from the IPC and CPC control are then sent as default to the controllers of the corresponding pitch actuators. The bending moments thus serve as a control variable for the individual blade adjustment.

Other methods determine the pitching and yawing moments by measuring the gondola acceleration via gyroscopes or by sensors, which measure the deformations of system components caused by the loads by means of distance measurements and thereby determine the loads. Such an approach is for example in the document DE 197 39 164 B4 disclosed.

However, rotor pitch angle control is too slow in some situations; so that the optimal angle of attack is not found. It is an object of the present invention to provide an improvement for the control of the angle of attack.

This object is solved by the subject matter of the independent patent claims. Advantageous embodiments emerge from the respective subclaims and the following description.

• – Einlesen eines Rotorblatt-Positionssignals, das eine Winkelposition des Rotorblattes bezüglich einer Drehachse eines Rotors der Windkraftanlage repräsentiert und/oder Einlesen einer Drehgeschwindigkeit des Rotorblattes um die Drehachse; und
• – Ermitteln des Anstellwinkel-Korrektursignals für das vorbestimmte Rotorblatt der Windkraftanlage unter Verwendung eines in einem Speicher abgelegten Zusammenhangs zwischen der Winkelposition und einem Anstellwinkel-Korrekturfaktor, wobei das Anstellwinkel-Korrektursignal den Anstellwinkel-Korrekturfaktor repräsentiert, der bei einer Verwendung eine Korrektur des individuellen Anstellwinkels für das vorbestimmte Rotorblatt bewirkt, so dass eine Wirkung eines Momentes auf das vorbestimmte Rotorblatt einer Wirkung eines Momentes auf zumindest ein weiteres Rotorblatt der Windkraftanlage angeglichen wird und wobei das Ermitteln unter Verwendung des eingelesenen Rotorblatt-Positionssignals und/oder der eingelesenen Drehgeschwindigkeit erfolgt.

The present invention provides a method of providing a pitch correction signal to a predetermined rotor blade of a plurality of rotor blades of a wind turbine, wherein the pitch correction signal is adapted to vary a signal to drive an individual pitch for the rotor blade, the method comprising the following steps having:

• - Reading a rotor blade position signal representing an angular position of the rotor blade with respect to a rotational axis of a rotor of the wind turbine and / or reading a rotational speed of the rotor blade about the axis of rotation; and
• Determining the pitch correction signal for the predetermined rotor blade of the wind turbine using a stored relationship in a memory between the angular position and an angle of attack correction factor, wherein the pitch correction signal represents the pitch correction factor which, in use, corrects the individual pitch for causing the predetermined rotor blade so that an effect of a moment on the predetermined rotor blade is adjusted to an effect of a moment on at least one further rotor blade of the wind turbine and wherein the determining is performed using the read rotor blade position signal and / or the read rotational speed.

• – eine Schnittstelle zum Einlesen eines Rotorblatt-Positionssignals, das eine Winkelposition des Rotorblattes bezüglich einer Drehachse des Rotors der Windkraftanlage repräsentiert und/oder Einlesen einer Drehgeschwindigkeit des Rotorblattes um die Drehachse; und
• – eine Einheit zum Ermitteln des Anstellwinkel-Korrektursignals für das vorbestimmte Rotorblatt der Windkraftanlage aus einem Speicher, wobei das Anstell-Winkel-Korrektursignal einen Anstellwinkel-Korrekturfaktor repräsentiert, der bei einer Verwendung eine Korrektur des individuellen Anstellwinkels für das vorbestimmte Rotorblatt bewirkt, so dass eine Wirkung eines Momentes auf das vorbestimmte Rotorblatt einer Wirkung eines Momentes auf zumindest ein weiteres Rotorblatt der Windkraftanlage angeglichen wird und wobei das Ermitteln unter Verwendung des eingelesenen Rotorblatt-Positionssignals und/oder der eingelesenen Drehgeschwindigkeit erfolgt.

Furthermore, the present invention provides a device for providing a pitch correction signal for a predetermined rotor blade of a plurality of rotor blades of a wind turbine, wherein the pitch correction signal for changing a signal for driving an individual pitch for the rotor blade is provided, the device comprising the following Features include:

• - An interface for reading a rotor blade position signal representing an angular position of the rotor blade with respect to a rotational axis of the rotor of the wind turbine and / or reading a rotational speed of the rotor blade about the axis of rotation; and
• A unit for determining the pitch correction signal for the predetermined rotor blade of the wind turbine from a memory, wherein the pitch angle correction signal represents a pitch correction factor, which causes in use a correction of the individual pitch for the predetermined rotor blade, so that a Effect of a moment on the predetermined rotor blade of an effect of a moment is adjusted to at least one further rotor blade of the wind turbine and wherein the determining is carried out using the read-in rotor blade position signal and / or the read rotational speed.

Also of advantage is a computer program product with program code, which is stored on a machine-readable carrier such as a semiconductor memory, a hard disk memory or an optical memory and which is used to carry out the method according to one of the embodiments described above, when the program on a control device or a device is performed.

The present invention is based on the recognition that a much faster and better control of the pitch angle of a rotor blade can be achieved when a correction signal is provided which reads out a correction factor for the pitch angle of a specific rotor blade in dependence on an angular position of this rotor blade from a memory. In this context, the angle of attack is defined as the angle at which the rotor blade on the rotor hub is rotated about the rotor blade axis relative to a zero position in the rotor plane, wherein in the zero position the rotor blade has a maximum thrust force from wind in the direction of the rotor axis. If the above-mentioned relationship is used, largely stationary forces on the rotor, which are corrected, for example, by an oblique flow of the rotor, wind accumulation effects on the tower of the wind turbine or forces due to wind shear as a function of the angular position of the rotor blade for the rotor blade individually so that the individual pitch control for the individual rotor blades can be limited only to the compensation of the effects of wind turbulence. This considerably relieves the regulation of the individual angles of attack. The stationary forces are taken into account for the determination of the angle of attack correction signal as a function of the angular position of the rotor blade, for example, the effects of wind shear or the wind accumulation effects on the tower of the wind turbine in different angular positions of the rotor blade have different weight.

The present invention offers the advantage that the separation of stationary effects and turbulence-induced dynamic effects in the load behavior of the rotor blades makes it possible to control the optimum angle of attack significantly more quickly and at the same time more precisely. In this case, the regulation need not yet be carried out directly by the present invention, but rather the essential core of the invention is the provision of a corresponding correction signal, the use of which is possible on the already known regulation of the individual angles of attack. The present invention offers the additional advantage that an existing control concept can continue to be used and is improved by the use of the present invention. This also allows retrofitting to existing wind turbines, which represents an additional economic advantage for the use of the present invention.

It is favorable if, in the step of determining, a change of the relationship stored in the memory takes place. Such an embodiment of the present invention offers the advantage that a rapid and flexible updating of the relationship stored in the memory to the corresponding wind conditions can be carried out on site.

According to another embodiment of the present invention, a determination of a wind speed at different segments of a rotor blade can be carried out in the step of determining for the change of the stored in the memory, wherein the determination of the wind speed at the individual segments of the rotor blade taking into account a determined current inclination of the rotor axis against the horizontal, a current distance of a rotor hub to a tower of the wind turbine, a determined oblique flow angle of wind with respect to the rotor axis in the region of the relevant segment, a current wind speed in the direction of the rotor axis in the region of the relevant segment of the rotor blade as a function of the height of the relevant segment over the earth's surface and / or a diameter of a tower of the wind turbine take place at a height of the relevant segment of the rotor blade. Such an embodiment of the present invention offers the advantage that the relationship stored in the memory very precisely reflects a correction factor which is used for Compensation of largely stationary disturbances can be used. In this way, the regulation of the individual angle of attack can be relieved and thus accelerated.

It is particularly advantageous if in the step of determining a segmentation of a flight circle of the rotor blade takes place around the rotor axis into different segments, wherein at least information about a load of the predetermined rotor blade in one of the segments of the flight circle is recorded and the recorded information for determining an angle of attack Correction signal of another rotor blade of the wind turbine is used, in particular wherein the recorded information is used to determine a Anstellwinkel-correction signal of a rotor blade of the wind turbine, which immediately follows the predetermined rotor blade in the direction of rotation of the rotor. Such an embodiment of the present invention offers the further advantage that the relationship stored in the memory can be adapted very flexibly and quickly to smaller local changes of the largely stationary disturbances. In this way, for example, a rotor blade directly following the rotor blade can already make use of the loading information which was detected by sensors from the first, that is, from the predetermined rotor blade.

In a particular embodiment of the present invention, in the step of determining for at least one segment information about a load of the rotor blade subsequent to the predetermined rotor blade are recorded, further wherein a deviation between the load of the predetermined rotor blade and the load of the other rotor blade, in particular the predetermined rotor blade immediately following rotor blade is determined and wherein the determined deviation is used for a determination of the load and / or a Anstellwinkel correction signal for a third rotor blade of the wind turbine, when the third rotor blade is in the segment of the flight circle. Such an embodiment of the present invention offers the advantage that, when the substantially stationary disturbance variable changes, an estimate of this change for a subsequent rotor blade can already be made. The provided pitch correction signal may thus be based on a prediction for varying (substantially stationary) disturbances, which is reflected by a further improvement in the speed and precision of the pitch control when using said pitch correction signal.

Also, according to a further embodiment of the present invention in the step of determining information about a load of the other rotor blade, in particular the rotor blade immediately following the predetermined rotor blade, be detected in the relevant segment and also in the memory, the information about the load of the rotor blade through the detected information about the load of the other rotor blade to be replaced. Such an embodiment of the present invention offers the advantage that the relationship stored in the memory is updated in very short time intervals, so that the provision of the pitch correction signal is based on the most accurate possible current basis of measured values. This ensures fast and highly accurate control of the individual pitch for a single rotor blade when using said pitch correcting signal to vary the individual pitch of this rotor blade.

• – Einlesen eines weiteren Rotorblatt-Positionssignals, das eine Winkelposition zumindest eines anderen Rotorblattes bezüglich einer Drehachse des Rotors repräsentiert; und
• – Ermittelns eines weiteren Anstellwinkel-Korrektursignals für das andere Rotorblatt der Windkraftanlage unter Verwendung des im Speicher abgelegten Zusammenhangs zwischen einer Winkelposition und einem Anstellwinkel-Korrekturfaktor, wobei das weitere Anstellwinkel-Korrektursignal einen Anstell-Winkel-Korrekturfaktor repräsentiert, der bei einer Verwendung eine Korrektur eines individuellen Anstellwinkels für das andere Rotorblatt bewirkt, so dass eine Wirkung eines Momentes auf das andere Rotorblatt einer Wirkung eines Momentes auf das vorbestimmte Rotorblatt der Windkraftanlage angeglichen wird und wobei das Ermitteln unter Verwendung des eingelesenen weiteren Rotorblatt-Positionssignals und/oder der eingelesenen Drehgeschwindigkeit erfolgt.

According to a further embodiment of the invention, the method may further comprise the following steps:

• - Reading another rotor blade position signal representing an angular position of at least one other rotor blade with respect to a rotational axis of the rotor; and
• Determining a further pitch correction signal for the other rotor blade of the wind turbine using the stored in the memory relationship between an angular position and a Anstellwinkel correction factor, wherein the further pitch correction signal represents a Anstell-angle correction factor, which in use a correction of a causes individual pitch of the other rotor blade, so that an effect of a moment on the other rotor blade of an effect of a moment on the predetermined rotor blade of the wind turbine is adjusted and wherein the determination is carried out using the read in another rotor blade position signal and / or the read rotational speed.

Such an embodiment of the present invention offers the advantage that not only an optimization of the pitch angle of a single rotor blade takes place, but that the optimization is carried out jointly for a plurality of rotor blades. This represents a further improvement in the regulation of the angles of incidence of the rotor blades of the wind power plant. In particular, this results in a reduction of the yawing and pitching moments on the tower or the nacelle of the wind turbine.

• – die Schritte des Verfahrens wie es vorstehend beschrieben wurde; und
• – Verändern des Signals zur Ansteuerung des individuellen Anstellwinkels für das Rotorblatt unter Verwendung des bereitgestellten Ansteuerwinkel-Korrektursignals.

In a further embodiment of the invention, a method for modifying a signal for actuating an individual angle of attack for the rotor blade can also be provided, this method having the following steps:

• The steps of the method as described above; and
• - Modifying the signal for controlling the individual pitch for the rotor blade using the provided drive angle correction signal.

Such an embodiment of the present invention offers the advantage of not only providing an angle of attack correction signal, but of actually changing the signal for driving the individual angle of attack. In this way, the advantages can be implemented, which are opened by providing the pitch correction signal.

The invention will now be described by way of example with reference to the accompanying drawings. Show it:

1 a block diagram of a control loop for adjusting the individual angles of incidence for rotor blades of the rotor of the wind turbine, wherein an embodiment of the present invention is used;

2 a front view of a wind turbine, wherein a representation of a segmentation of the rotor blades for determining the current pitch correction factor is shown;

3 a representation of a wind shear at different heights above the earth's surface and a side view of a wind turbine, in which the rotor axis is shown tilted;

4 a plan view of a wind turbine, wherein the rotor blades are flowed by wind obliquely;

5 a representation for explaining the Turmstaueffekts;

6 Representations to illustrate the effect of measured load values on subsequent rotor blades of the wind turbine;

7a a graph of load values in a circle segment of a rotor blade in time sequence with an increase of wind;

7b a diagram showing a change of a correction factor for the angle of attack for the in 7a shown increase in wind load within the flight segment of the rotor blade at different times;

8th a block diagram of a control loop for adjusting the individual angles of incidence for rotor blades of the rotor of the wind turbine, wherein a further embodiment of the present invention is used; and

9 a flowchart of an embodiment of the present invention as a method.

The same or similar elements may be provided in the following figures by the same or similar reference numerals. Furthermore, the figures of the drawings, the description and the claims contain numerous features in combination. It is clear to a person skilled in the art that these features are also considered individually or that they can be combined to form further combinations not explicitly described here. Furthermore, the invention in the following description may be explained using different dimensions and dimensions, wherein the invention is not limited to these dimensions and dimensions to understand. Furthermore, method steps according to the invention can be repeated as well as carried out in a sequence other than that described. If an embodiment includes a "and / or" link between a first feature / step and a second feature / step, this may be read such that the embodiment according to one embodiment includes both the first feature / the first feature and the second feature / the second step, and according to another embodiment comprises either only the first feature / step or only the second feature / step.

An important aim of the present invention is to be seen in that a feedforward control for the IPC control should be realized or made possible. As a result, a significantly improved performance of the IPC control can be achieved. The invention can be very easily combined with the known IPC control methods so that already existing and implemented IPC control strategies can be supplemented. For this purpose, for the individual pitch control of a rotor blade, the measurement information stored up to a complete rotor circulation should be used in the best case of all rotor blades. The strain gauges obtained from the measurement information can then be used to estimate the expected rotor loads. Based on this estimate, a desired trajectory of the individual pitch angles can then be calculated and used for the precontrol of the pitch actuators.

• 1) die Neigung der Rotorachse gegen die Horizontale (üblicherweise um ca. 5°). Dadurch entstehen Momente durch die auf die Blätter wirkende Gewichtskraft, sowie eine sich periodisch ändernde Anströmung; da sich die Blattspitzen während eines Umlaufs vor und zurück bewegen.
• 2) Fehler in der Anströmung durch den Turmschatten;
• 3) Abhängigkeit der Windgeschwindigkeit von der Höhe über dem Boden durch Windscherung;
• 4) Schräganströmung der Rotorblätter; und
• 5) Sonstige Effekte (z. B. Abschattung einer Hälfte der Rotorfläche durch andere Anlagen, etc.).

An important aspect of the present invention is to be seen in that the IPC control can be extended by a noise compensation, which is to compensate for the yawing and pitching moments at the wind turbine, which are caused by known interference effects. These disruptive effects include, for example:

• 1) the inclination of the rotor axis against the horizontal (usually about 5 °). This creates moments due to the force acting on the leaves weight, as well as a periodically changing flow; because the blade tips move back and forth during one revolution.
• 2) errors in the flow through the tower shadow;
• 3) dependence of wind speed on altitude above ground due to wind shear;
• 4) oblique flow of the rotor blades; and
• 5) Other effects (eg shading of half of the rotor surface by other equipment, etc.).

Since all of these effects change only slowly over time, they can be eliminated by means of noise compensation before they can be measured at the output. For this purpose, first the course of a correction variable for the individual pitch angle for each rotor blade is determined, which is necessary to eliminate the interference. This course is then added as a noise compensation additive in addition to the individual pitch angle calculated by the IPC controller and supplies the received signal to a pitch actuator. A basic procedure in the determination of the corrected individual angle of attack is shown in the block diagram according to FIG 1 recognizable.

The block diagram shows from the 1 like a loop 100 could be configured, which uses the present invention. Here is the angle of in 1 not shown rotor blades of a wind turbine 110 regulated. This regulation is dependent on the speed of the wind 115 standing on the rotor blades of the wind turbine 110 acts. At the wind turbine 110 become different measurands through sensors 120 detected, such as the rotational speed of the rotor, the angular velocity of the rotor, one or more angular positions of the rotor blades or bending moments that occur at the blade roots of the rotor blades. These measurements 120 such as Ω _1,2,3 (the angular positions of the rotor blades 1, 3 and 3, respectively), ω, M _1,2,3 (the moments of the rotor blades 1, 2 and 3, respectively) become one unit 125 for operation of the wind turbine 110 , an IPC controller 130 and a device 135 and via an interface 136 a memory 137 which is a unit representing the pitch correction signal 139 also referred to as βSt _1,2,3 for the disturbance variable signal for the first, second and third rotor blade, provides. In particular, through the memory 137 a pitch correction signal for each of the rotor blades of the wind turbine 110 to be provided. In the store 137 is a relationship between the angle of attack correction signal for at least one of the rotor blades of the rotor of the wind turbine 110 filed in response to a current angular position of the respective rotor blade and / or an angular velocity of the rotor for the correction of the individual angle of attack 139 of the relevant rotor blade is output.

In the device 135 can according to the description described in more detail below corrections of the memory 137 stored context and these corrections in memory 137 be filed. This allows the memory 137 stored context are kept current, so that a very precise control of the angle of attack is possible.

The unit 125 for operation provides on the basis of the speed ω general control signals that optimize the power output of the wind turbine 110 affect. For example, the unit delivers 125 for operation a current generator torque 140 which is directly the wind turbine 110 is made available to control the speed of the generator and thus to optimize the power output of the generator of the wind turbine. Furthermore, the unit delivers 125 for operation a signal 142 , which has a common angle of attack for all rotor blades of the rotor Wind turbine 110 represents, thereby taking into account the current wind speed 115 (and possibly the current wind direction) the wind turbine 110 works in their current optimal performance point.

The IPC controller 130 uses, for example, one or more signals over moments M _1,2,3 , which are detected at the individual rotor blade roots, and can therefrom for at least one, but better for each of the individual rotor blades an individual angle of attack 145 (designated by β _{IPC 1,2,3} ).

The Angle Correction Signal 139 for a given rotor blade, the signal 145 , which represents the individual angle of attack for the relevant rotor blade and the signal 142 that represents a common angle of attack of all rotor blades can then be additive to a corrected angle of attack drive signal 150 be linked. From this corrected pitch drive signal 150 a more detail hereinafter described signal is β _1,2,3 for a current angle of attack for the corresponding rotor blade 1, 2 or 3 subtracts the signal obtained by subtracting a lower-level Anstellwinkelregler 155 is supplied, which is designed for example as a P-controller with the control factor k _A. That of the subordinate pitch controller 155 receive signal is additive with a signal from a feedforward control unit 160 linked to the pitch actuator. The thus-linked signal subsequently becomes an angle-of-attack actuator 165 supplied with the transformation rule G _A , which sets the actual angle of attack for the relevant rotor blade. A signal that represents this actual angle of attack for the relevant rotor blade, as the above current angle of attack signal 150 deducted. The feedforward control unit 160 for the pitch actuator thereby results in a prediction of the expected angle of attack on the basis of the pitch correction signal 139 through, so that a faster control of the corrected individual angle of attack for the relevant rotor blade is possible. The above description may also apply to each individual rotor blade of the rotor of the wind turbine 110 be performed so that an optimization of the control of the individual angle of attack for the rotor blades is possible. However, it is not necessary that the pitch be optimized for all rotor blades.

Since the course of the size for the noise compensation in advance is known, can for the subordinate pitch controller 155 a pilot control can be realized, which provides a significantly improved and faster follow-up control of the pitch actuator 165 allows. This allows the actuator resulting from the noise compensation using the Anstellwinkel correction signal 139 set pitch components practically without delay. With correctly calculated pitch curve for the noise compensation, the asymmetrical loads can be completely compensated for at a constant, turbulence-free wind. The noise compensation uses a curve in the memory 137 which contains a relationship for the pitch or pitch required for noise compensation for each blade. This curve can be through the device 135 be calculated by in the device 135 the course of the wind speed is calculated on individual leaf elements. Subsequently, the curve for the pitch angle is optimized so that the resulting flow conditions result in no or very low asymmetric moments.

However, the curve for the pitch angle can also be adapted continuously in an improved embodiment of the invention by taking the measured data 120 the wind turbine continuously read out the parameters of wind shear, tower backlog, etc. and using these parameters in the memory 137 stored context is adjusted. In this case, the individual disturbing effects should not be resolved separately, but an algorithm can be implemented, which adjusts the pitch curve over the rotor blade position so that all disturbing effects, which do not originate from the turbulence of the wind, are compensated.

For the calculation of the wind speeds at the individual rotor blades, for example, a consideration of individual segments 200 of the respective rotor blades 210 the wind turbine 110 be used as in the 2 is shown. This is a distance r of the relevant segment 200 from the hub of the rotor and the rotational speed ω and / or the angular position Ω of the rotor blade 210 takes into account where the segment in question is currently located. In this case, a coordinate system is considered in which the z and y axes as shown 2 run.

Furthermore, the wind shear at different heights H above the earth's surface can be taken into account for the calculation of the wind speeds. For this purpose, for example, a pitch angle δ of the rotor axis 310 relative to the horizontal and a distance of the rotor hub 320 towards the center of the tower of the wind turbine, as reflected in the 3 is shown schematically. In the 3 Furthermore, the course of the x-coordinate for a coordinate system is entered, as it is used in the calculation of wind speeds. In determining the wind shear, different wind speeds are to be taken into consideration, which according to the left-hand schematic illustration 3 in different height above the earth's surface can occur, with a greater wind speed can be observed at a greater height above the earth's surface, as close to the earth's surface.

Also, for example, in the determination of the wind speeds, the oblique flow of the rotor blades 210 considered under the angle of attack γ relative to the rotor axis, as shown schematically in FIG 4 is apparent.

In addition, an air congestion on the tower of the wind turbine can also be taken into account when calculating the wind speeds, as shown in the illustration 5 is clarified. It is in the 5 represented by the solid lines, a flow behavior of wind around a fixed tower of a wind turbine, being simplified by a tower radius r at the level of the considered segment 200 at an angle φ and a distance r of this segment 200 from the middle of the tower is assumed. The flow velocity of the wind is designated by the variable u.

Using the above-mentioned relationships, it is now possible to estimate the wind speeds in different coordinate directions with the aid of the following formulas: z = r · cosΩ · cosδ; y = -r · sinΩ; x = -h + r · sinδ · cosΩ;

wobei φ = arctan x / y gilt. Auch kann als Exponent statt 1/7 der Wert des Scherungskoeffizienten α verwendet werden. Dieser kann sich mit der Zeit ändernFurthermore, the following relationship is used for wind speeds in the x and y directions:

where φ = arctane x / y applies. Also, the value of the shear coefficient α can be used as an exponent instead of 1/7. This can change over time

die Komponente des Windes, die durch die Windscherung verursacht ist und der Term

diejenige Komponente, die durch das Turmstaumodell über den Potentialströmungsansatz berechnet werden kann. Ferner werden für die Windgeschwindigkeit beim Potentialstaumodel die folgenden beiden Gleichungen verwendet:

und

Here, in the equations (1) and (2), the term represents

the component of the wind caused by the wind shear and the term

the component that can be calculated by the tower surge model via the potential flow approach. Furthermore, the following two equations are used for the wind speed in the potential storage model:

and

The total rotor flow, ie the wind speed of the rotor, can be determined in a simplified manner, neglecting the small proportion of v _{y, as} follows: ν = ν _x · cosγ + r · sinδ · ω · sinΩ. (3)

In this case, the term cos γ maps the oblique flow of the rotor, while the term r · sinδ · ω · sinΩ represents the velocity on the basis of the axial inclination.

Using the above formulas, it is possible to store in the memory 137 changed context for the pitch correction in relation to the current angular position of the rotor and / or the speed of the rotor change. This can be done by the unit 135 take place, in which a corresponding model is deposited, which angle of attack for a single rotor blade at which wind speed from which direction is required in order to achieve an optimal ie symmetrical as possible reduction of the load of the wind turbine. It should be noted that the above quantities reflect the steady state conditions that can not change quickly, ie in the range of a few tens of seconds. For the obtained favorable angle of attack then a corresponding correction factor can be determined, which is added to an individual Anstellwinkelsignal, which on the basis of very short-term (ie changing in the range of seconds) air turbulence by the IPC controller 130 is determined.

An important object of the invention according to a further embodiment of the invention is to realize an active precontrol of the pitch actuators based on the load measurement series measured in the cycle of rotation of the rotor. The load curve of a rotor blade is here considered as the expected load curve of the Nachläufers (ie the directly following rotor blade) of a circle segment of the rotor blades, wherein the flight circle denotes the surface which sweep the rotor blades during rotation about the rotor hub. To illustrate, the following diagrams are from the 6 , In the two left as well as in the two right diagrams, the measured impact moment loads of the rotor blades (lower diagrams) are compared to the measured wind speeds (upper diagrams). The passage order of a rotor sector (ie, the considered segment of the circle of rotor blades) is 3-2-1, that is, with respect to the rotor blade 2, sheet 3 is the precursor and sheet 1 is the follower. If the load curves shown are each shifted by t = T / 3 (with T of the rotor cycle time) to the right in the time rail, the load curves in the lower diagrams of the 6 are almost brought into line, that is, the solid line corresponds essentially to the dashed line shown and the dashed line shown can then also represent the dotted line shown; apart from changes in the load moments, which tend to be the same for all three rotor blades.

The load curves within a main sector are thus assigned to the respective subsequent rotor blade. In order to avoid too much uncertainty about the prediction, only the load curve of the precursor for the prediction of the load of the trailer is considered. The rotor surface is discretized for this purpose (eg with a rotor azimuth angle of 1 degree per segment). During the rotor revolution, the measured loads are assigned to the corresponding rotor azimuth angles when the discretization section or the discretization step is swept over. In this way, when storing a complete rotor revolution, three (or four) measured values per rotor azimuth angle segment and revolution can be realized. The principal idea for the pilot control according to this embodiment is to use the sensor data of the individual rotor blades measured during a third revolution (i.e., 120 degrees) as the basis for the trajectory planning of the pitch angles of subsequent rotor blades. The cyclic load curves of wind turbines that can be detected in measurements and simulations make it possible to predict the expected load.

Thus, the trajectory planning is limited to 3 * 120 ° sectors, for each of which a desired trajectory of the pitch adjustment is calculated. This desired trajectory may be for each of the sectors in the memory 137 stored and used to correct the individual angle of attack of a rotor blade, which is located in the sector concerned. After sweeping a 120 ° sector, the trajectory planning for this sector will be updated based on the new rotor blade data, which has just passed through this sector. In the lower left diagram from the 6 (Load curve gust) can be seen an increasing rotor load in the time range 10-22 seconds and a decreasing load in the range 22-30 seconds. As a gust of wind or generally a change in wind speed (and thus the rotor load) can be calculated for the individual rotor segments, a load gradient by means of the measured data.

This change in wind speed, which may also be referred to as a gradient, may then be used as a correction factor for the load curves. The prerequisite for the consideration of the correction factor in this case is a clearly ascertainable tendency on the basis of the measured data series of the corresponding rotor sectors. Such a tendency is for example from the diagram 7a to recognize, in which the wind speed (and thus the moment load M) continuously increases in one and the same rotor segment over the one-third cycles T. This can be a correction factor k = Δy / 3ΔT be determined by the load trajectory is changed or should be changed accordingly. For example, this is done as shown in the 7B in which the reference trajectory represented by a solid line represents the change using the correction factor whose effect in the 7B represented by the arrows is converted into a corrected desired trajectory is shown in dashed lines. This allows a very short-term change of the correction factors and thus a very fast adaptation of the pitch angle correction signal to be set to the current wind conditions in the respectively considered rotor sector. The procedure described above can then also be carried out for a plurality of rotor sectors, so that as far as possible a short-term update of the wind conditions is possible for the entire flight circle of the rotor. Based on the (corrected) load curves, a feedforward control of the pitch actuators in the context of IPC control can be realized.

Such an embodiment could be designed in accordance with a block diagram 8th be reproduced. Here is in the memory 137 a trajectory plan for the individual rotor sectors included by the unit 135 each be updated. Compared to the block diagram accordingly 1 designed embodiment is thus in the memory 137 no longer relates a relationship between an angular position and the pitch correction factor for a complete revolution rotor blade, but stores the correction factors determined for individual rotor sectors (or at least one sector) and updated after sweeping the trailing rotor blade. In this way, a highly accurate and rapid control or correction of the individual angles of attack of the rotor blades or is achieved.

Furthermore, the present invention provides a method 900 for providing a pitch correction signal for a predetermined rotor blade of a plurality of rotor blades of a wind turbine as shown as a flow chart in the 9 is shown. In this case, the pitch correction signal for changing a signal for driving an individual angle of attack for the rotor blade is provided. The procedure 900 includes a step of reading 910 a rotor blade position signal representing an angular position of the rotor blade with respect to an axis of rotation of the rotor blade and / or reading a rotational speed of the rotor blade about the axis of rotation. Furthermore, the method comprises 900 a step of determining 920 the pitch correction signal for the predetermined rotor blade of the wind turbine using a stored in a memory relationship between an angular position and an angle of attack correction factor, the pitch correction signal representing the pitch correction factor, which in use a correction of the individual angle of attack for the predetermined Rotor blade causes, so that an effect of a moment on the predetermined rotor blade of an effect of a torque is adjusted to at least one further rotor blade of the wind turbine and wherein the determining is carried out using the read rotor blade position signal and / or the read rotational speed.

The exemplary embodiments shown are chosen only by way of example and can be combined with one another.

LIST OF REFERENCE NUMBERS

100

Apparatus for providing a pitch correction signal

110

Wind turbine

120

Sensor signals from sensors on or in the wind turbine

125

Unit for the operation of the wind turbine

130

Controller for determining the individual angles of attack

135

Unit for changing the relationship stored in the memory

136

interface

137

Storage

139

AoA Korektursignal

140

Signal representing the generator torque

142

Signal representing the common pitch angle for all rotor blades

145

Signal for individually controlling the angle of attack from the IPC controller

150

corrected individual pitch control signal

155

subordinate pitch controller

160

Feedforward control for the pitch actuator / pitch actuator

165

Pitch actuator, pitch actuator

200

Segment of a rotor blade

210

rotor blade

310

Rotor axis of rotation

320

rotor hub

900

A method of providing a pitch correction signal

910

Step of reading in

920

Step of determining

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19739164 B4 [0003]

Claims (10)

Procedure ( 900 ) for providing a pitch correcting signal (β ₁ , 139 ) for a predetermined rotor blade ( 210 ) of a plurality of rotor blades of a wind turbine ( 110 ), wherein the pitch correction signal for changing a signal ( 145 ) is provided for controlling an individual angle of attack for the rotor blade, wherein the method ( 900 ) comprises the following steps: - reading in ( 910 ) of a rotor blade position signal (Ω ₁ , 120 ), which has an angular position (Ω ₁ ) of the rotor blade with respect to an axis of rotation ( 310 ) of the rotor of the wind turbine ( 110 ) and / or reading a rotational speed (ω) of the rotor blade about the axis of rotation ( 310 ); and - determining ( 920 ) of the pitch correction signal ( 139 ) for the predetermined rotor blade of the wind turbine using one in a memory ( 137 ) Stored relationship between an angular position (Ω ₁₎ and an angle correction factor (β _1), said angle correction signal represents the pitch correction factor, the correction of the signal (when using β _IPC1, 145 ) for controlling the individual angle of attack for the predetermined rotor blade is effected, so that an effect of a moment (M ₁ ) on the predetermined rotor blade of an effect of a moment (M ₂ , M ₃ ) is adjusted to at least one further rotor blade of the wind turbine and wherein the determining using the read-in rotor blade position signal (Ω ₁ ) and / or the read rotational speed (ω). A method according to claim 1, characterized in that in the step of determining a change in the memory deposited relationship takes place. Method according to claim 2, characterized in that, in the step of determining for the change of the relationship stored in the memory, a determination of a wind speed ( 115 ) on different segments ( 200 ) of a rotor blade, wherein the determination of the wind speed at the individual segments of the rotor blade taking into account a determined current inclination (δ) of the rotor axis ( 310 ) against the horizontal, a current distance of a rotor hub ( 320 ) to a tower of the wind turbine, a determined oblique angle of incidence (γ) of wind with respect to the rotor axis in the region of the relevant segment, a current wind speed in the direction of the rotor axis in the region of the relevant segment of the rotor blade as a function of the height (H) of the relevant Segmentes above the earth's surface and / or a diameter (a) of a tower of the wind turbine takes place at a height of the relevant segment of the rotor blade. Method according to one of the preceding claims, characterized in that in the step of determining a segmentation of a flight circle of the rotor blade about the rotor axis into different segments, wherein at least one information about a load of the predetermined rotor blade in one of the segments of the flight circle is recorded and the recorded Information is used to determine a Anstellwinkel-correction signal of another rotor blade of the wind turbine, in particular wherein the recorded information is used to determine a Anstellwinkel-correction signal of a rotor blade of the wind turbine, which immediately follows the predetermined rotor blade in the direction of rotation of the rotor. A method according to claim 4, characterized in that in the step of determining for at least one segment information about a load of the rotor blade immediately following the predetermined rotor blade is recorded, further wherein a deviation between the load of the predetermined rotor blade and the load of the other rotor blade, in particular of the rotor blade immediately following the predetermined rotor blade, and wherein the determined deviation is used for a determination of the load and / or a pitch correction signal for a third rotor blade of the wind turbine when the third rotor blade is in the one segment of the flight circle. A method according to claim 4 or 5, characterized in that in the step of determining information about a load of the further rotor blade, in particular the rotor blade immediately following the predetermined rotor blade, is detected in the relevant segment and further in the memory, the information about the load of the rotor blade is replaced by the detected information about the load of the other rotor blade. Method according to one of the preceding claims, characterized in that the method further comprises the following steps: - reading in another rotor blade position signal (Ω ₂ ), which represents an angular position of at least one other rotor blade with respect to a rotational axis of the rotor; and Determining another angle correction signal ( 139 , β _St2 ) for the other rotor blade of the wind turbine using the stored relationship between an angular position and an angle of attack correction factor, wherein the further angle of attack correction signal represents an angle of attack correction factor which, in use, corrects an individual angle of incidence for the other Rotor blade causes, so that an effect of a moment on the other rotor blade of an effect of a moment on the predetermined rotor blade of the wind turbine is adjusted and wherein the determining is carried out using the read in another rotor blade position signal and / or the read rotational speed. A method of modifying a signal to drive an individual pitch for the rotor blade, the method comprising the steps of: - the steps of the method according to any one of claims 1 to 7; and changing the signal for driving the individual _pitch angle (β _IPC1 ) for the rotor blade using the provided drive angle correction signal (β ₁ ). Contraption ( 100 ) for providing an angle-of-attack correction signal ( 139 , β _St1 ) for a predetermined rotor blade of a plurality of rotor blades ( _{US Pat.} 210 ) of a wind turbine ( 110 ), wherein the pitch correction signal for changing a signal ( 145 ) is provided for controlling an individual angle of attack for the rotor blade, the device having the following features: an interface ( 136 ) for reading in a rotor blade position signal (Ω ₁ ), which is an angular position of the rotor blade with respect to a rotational axis ( 320 ) represents the rotor of the wind turbine and / or reading a rotational speed (ω) of the rotor blade about the axis of rotation; and - one unit ( 135 . 137 ) for determining the _pitch correction _signal (β _St1 ) for the predetermined rotor blade of the wind turbine from a memory ( 137 ), wherein the _pitch correction _signal represents an angle of attack correction factor which, in use, _effects a correction of the individual _pitch angle (β _IPC1 ) for the predetermined rotor blade such that an effect of a moment (M ₁ ) on the predetermined rotor blade is an effect of a moment (M ₂ , M ₃ ) is adapted to at least one further rotor blade of the wind turbine and wherein the determining is carried out using the read-in rotor blade position signal and / or the read rotational speed. Computer program product with program code for carrying out a method according to one of claims 1 to 8, when the program is executed on a control device or a device.

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