DE102014204017A1 - Method and device for rotor blade adjustment for a wind turbine - Google Patents

Abstract

A method for rotor blade adjustment for a wind turbine (100) is presented, wherein the wind turbine (100) has a rotor (104) with a plurality of rotor blades (106). The method includes a step of reading in a plurality of blade load signals (110) and a step of determining a plurality of pitch angles (112) for each rotor blade (106) of the plurality of rotor blades (106) using the plurality of blade load signals (110).

Description

The present invention relates to a method for rotor blade adjustment for a wind turbine, to a corresponding device for rotor blade adjustment for a wind turbine and to a corresponding computer program.

Due to manufacturing tolerances rotor blades of wind turbines have different properties. Both geometry and mass distribution differ from sheet to sheet. This results in different aerodynamic properties of the rotor blades, the total mass and the position of the center of gravity varies. From the rotor blades produced, therefore, sets of three rotor blades are assembled after production, which have as much as possible the same mass and center of gravity. If necessary, the mass or the center of gravity is adjusted by trimming. This avoids that the rotor of the wind turbines, to which these blades are mounted, has a large imbalance. Different aerodynamic behavior is not considered in the composition of the rotor blade sets. Partly after the installation of the blades on the wind turbine further measurements are carried out. This is not the case in general. Firstly, the vibration excitation resulting from the unbalance is measured during operation of the wind turbine. Subsequently, additional weights are applied in order to further reduce the imbalance or the resulting vibration excitation.

It is the object of the present invention to reduce a load on a wind turbine by acting on the rotor due to imbalance forces.

This object is achieved by a method for rotor blade adjustment for a wind turbine, a corresponding device for rotor blade adjustment for a wind turbine, the steps of the method in corresponding facilities executes and solved a computer program according to the main claims. Advantageous embodiments emerge from the respective subclaims and the following description.

The presented approach is based on the finding that manufacturing tolerances lead to differences in the aerodynamic behavior and thereby to different forces acting on the rotor blades. By changing the pitch angle of a rotor blade, the forces can be changed. When a rotor of a wind turbine has a plurality of rotor blades, the pitch angles of the plurality of rotor blades may be adjusted so that the forces acting on each rotor blade are equal. Advantageously, thereby the life of a wind turbine can be extended.

The approach presented here provides a rotor blade adjustment method for a wind turbine comprising a rotor having a plurality of rotor blades, the method comprising the steps of:
Reading a plurality of sheet load signals; and
Determining a plurality of correction angles for a pitch angle per rotor blade of the plurality of rotor blades using the plurality of blade load signals.

A wind power plant can be understood as a wind energy plant. A wind turbine may include a rotor having a plurality of rotor blades. The rotor may have two rotor blades. In particular, the rotor may have three rotor blades. Depending on the rotor blade, a blade load signal can be detected and provided. Thus, a blade load signal can be read in for each rotor blade. In this case, a blade load signal may represent a load or an average load of a rotor blade during at least one rotation of the rotor. A pitch angle can be set for each rotor blade. A pitch angle can be understood as an angle of attack of the rotor blade or an angle about which the rotor blade is rotated about its longitudinal axis. A default for a pitch angle may be the same for the majority of the rotor blades. In the step of determining, a correction angle for the pitch angle for each rotor blade of the rotor can be determined. The correction angle and the pitch angle command from a speed control can be added to be used as a set value.

In the read-in step, the plurality of blade load signals may represent a load, in particular an average load, per rotor blade of the plurality of rotor blades during at least one rotation of the rotor. Advantageously, measurement errors can thus be compensated.

In the read-in step, the read-in plurality of blade load signals can be determined using one signal each of at least one strain gauge and additionally or alternatively an optical sensor and additionally or alternatively an inertial sensor per rotor blade. The sensors may provide sensor signals representing blade load of the rotor blade. Thus, the plurality of blade load signals may be sensor signals. A leaf load signal can be determined via a mean blade deflection. A blade deflection can be determined with a laser-based measuring system. Advantageously be resorted to existing sensor signals in a wind turbine.

In a step of determining preceding the step of determining, an aerodynamic imbalance may be determined using the plurality of blade load signals. In this case, in the step of determining, the plurality of correction angles for the pitch angle per rotor blade can be determined using the aerodynamic unbalance in order to reduce the aerodynamic imbalance. Advantageously, at least one leaf load signal per rotor blade can represent a load for the associated rotor blade. In this case, an average load for all rotor blades can be determined and each rotor blade a deviation from the average load can be determined. This is simply an aerodynamic imbalance determined.

In a step of providing, a correction signal using the plurality of correction angles may be provided to adjust the plurality of rotor blades. The correction signal may represent the correction angle. In this case, the correction signal can be easily and efficiently provided to a control unit for adjusting the pitch angle. Advantageously, a closed loop can be formed.

In the reading-in step, information about wind speed and wind turbine actual power information may be read in, and in a further step of determining, a power quotient may be determined using the actual wind turbine power and wind speed information In the step of providing, the correction signal may be provided using the power quotient, and in a step of optimizing, at least the reading step, the further step of determining, and the providing step may be repeated until the power quotient reaches a maximum , The wind speed can be understood as meaning a value representing a speed of the wind in the area of the wind turbine. Advantageously, the pitch angles can be optimized in a partial load range for increased yield. A quotient of the actual power and a theoretical power of the wind turbine determined using the wind speed can be optimized. In this case, for example, a hill climbing algorithm can be used.

It is also favorable if, in a step of averaging, the plurality of sheet load signals read in the step of reading are averaged to obtain a plurality of averaged sheet load signals and additionally or alternatively averaged the wind speed information and the actual wind turbine power information to obtain information about an average wind speed and an average actual power information. In the following step of determining and additionally or alternatively the further step of determining, using the plurality of averaged sheet load signals and additionally or alternatively the information on an average wind speed and additionally or alternatively the information on an average actual power, the plurality of correction angles and or alternatively the performance quotient can be determined. By a step of averaging short-term fluctuations can be compensated. Thus, in the read-in step, the plurality of leaf load signals, the wind speed, and the actual power information may be read in over a predefined period of time, and averaged values may be determined over the predefined time period. The predefined period can be, for example, one minute, in particular 5 minutes or particularly advantageously 10 minutes. It also periods of different or varying duration can be used.

In the read-in step, information about a power of at least one further wind turbine can be read in, wherein in the step of determining the plurality of correction angles can be determined using the information about the power of the further wind turbine. Advantageously, further signals or information can be used for optimization. In this case, uncertainties of a single sensor signal can be compensated. Also, a possibly failing sensor signal can be compensated.

The approach presented here also creates a device that is designed to implement or implement the steps of a variant of a method presented here in corresponding devices. Also by this embodiment of the invention in the form of a device, the object underlying the invention can be solved quickly and efficiently.

In the present case, a device can be understood as meaning an electrical device which processes sensor signals and outputs control and / or data signals in dependence thereon. The device may have an interface, which may be formed in hardware and / or software. In the case of a hardware-based embodiment, the interfaces can be part of a so-called system ASIC, for example, which contains a wide variety of functions of the device. However, it is also possible that the interfaces have their own, integrated Circuits are or at least partially consist of discrete components. In a software training, the interfaces may be software modules that are present, for example, on a microcontroller in addition to other software modules.

Also of advantage is a computer program product or computer program with program code which can be stored on a machine-readable carrier or storage medium such as a semiconductor memory, a hard disk memory or an optical memory and for carrying out, implementing and / or controlling the steps of the method according to one of the embodiments described above is used, especially when the program product or program is executed on a computer or a device.

Advantageously, the electricity production costs can be reduced at wind turbines. Aerodynamic imbalances of the rotor can be advantageously reduced. As a result, the loads on the wind turbine can decrease, the service life can rise and maintenance costs can be avoided. In one embodiment, the power can be maximized in the partial load range, so that the energy yield increases. Advantageously, installation costs can be reduced according to one aspect of the present invention, since an exact adjustment of the pitch angle of the rotor blades during assembly is not required, but can then be carried out during operation.

The pitch angles of the rotor blades can be changed by constant offsets, which are adjusted in small steps. The design of the pitch drives and blade bearings can be maintained unchanged. The sensors for measuring the wind speed can already be present on the nacelle. Also, a measurement of the performance of the wind turbine can already be present.

A sensor for measuring the sheet load can be retrofitted. The demands on the life of the sheet sensors can be low. The optimization of the pitch angle can be done during the first months of operation of the wind turbine. If a sensor subsequently fails, regular recalibration can not be carried out. Nevertheless, the wind turbine can continue to operate. An exchange of the sensors can then be carried out, for example, at the next regular maintenance.

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

1 a simplified representation of a wind turbine with a device for adjusting the rotor blade according to an embodiment of the invention;

2 a schematic representation of a device for adjusting the rotor blade for a wind turbine according to an embodiment of the invention;

3 a detailed view of a rotor of a wind turbine according to an embodiment of the invention;

4 a representation of strain gauges in the region of a blade root of a rotor blade of a wind turbine according to an embodiment of the invention;

5 a detailed view of a rotor blade of a wind turbine with a measurement of a sheet load according to an embodiment of the invention; and

6 a flowchart of a method for rotor blade adjustment for a wind turbine according to an embodiment of the invention.

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.

1 shows a simplified representation of a wind turbine 100 with a device 102 for rotor blade adjustment according to an embodiment of the invention. In the device 102 it concerns a control unit, which in 2 is described in more detail. The wind turbine 100 has a rotor in the embodiment shown 104 with three rotor blades 106 on. On each rotor blade 106 is a sensor 108 arranged to a rotor blade load for the rotor blade 106 to investigate. The sensor 108 is formed, a sheet load signal 110 provide. In this case, a sensor signal of the sensor 108 the sheet load signal 110 correspond. Alternatively, from the sensor signal a sheet load signal 110 be won. Depending on the exemplary embodiment, the sensor is 108 around a strain gauge 108 , an optical sensor 108 or an inertial sensor 108 , The leaf load signal 110 represents a load on the rotor blade. A pitch angle 112 is for each rotor blade 106 adjustable. The pitch angle 112 is adjustable via a pitch angle signal. This is where the sits Pitch angle signal in the embodiment shown together from a signal for a desired angle for the pitch angle of, for example, a speed control and a signal for a correction angle together. The correction angle is in the device 102 determined for the rotor blade adjustment, wherein for each rotor blade 106 a correction angle is determined. The device 102 to the rotor blade adjustment is in 2 shown and described in more detail.

The wind turbine 100 points in the in 1 shown embodiment, a sensor 114 for detecting the wind speed. At the sensor 114 depending on the embodiment, it is an anemometer 114 to a LIDAR-based wind sensor 114 or another sensor 114 which is capable of detecting a wind speed. The wind gets through a wind speed 116 representing arrows in 1 shown.

An aspect of the device 102 for rotor blade adjustment is to continuously monitor the aerodynamic imbalance during operation and possibly add offsets to the pitch angles for the individual rotor blades in order to reduce the aerodynamic imbalance. In addition, in one embodiment, a possibility is provided for the energy output of the rotor 104 to optimize by the pitch angle 112 the rotor blades 106 in the partial load range to the pitch angle required for optimum performance 112 to be optimized.

The device 102 for the rotor blade adjustment is formed, a measurement of the resulting from the aerodynamic forces load of the rotor blades 106 to perform or receive corresponding signals. Then the pitch angles 112 the rotor blades 106 adjusted so that the mean measured load during one rotor revolution in the three rotor blades 106 is identical. In addition, in one embodiment in the partial load range, the power of the wind turbine 100 measured. Subsequently, the pitch angle 112 the three rotor blades 106 varies in small increments, trying to get the power on the rotor 104 to increase.

For wind turbines 100 There are different sensors 108 for measuring the load on the rotor blades 106 , Wind turbines 100 are already partially with such sensors 108 equipped, for example, for condition monitoring of the rotor blades, also referred to as "condition monitoring".

In one embodiment, to measure the load of the rotor blades 106 For example, strain gauges applied to the blade root of the rotor blades 106 are attached. These sensors 108 measure the local strain resulting from the blade loading. However, the measurement results on different rotor blades 106 distinguish when the sensors 108 were not glued in exactly the same place or if the wall thickness in the area of the sensors 108 between the rotor blades 106 different. For this reason, measuring global leaf loading is beneficial. For this purpose, the blade deflection in the wind direction, also known as impact bending, measured. This is possible, for example, with a camera, the displacement of marks in the rotor blade 106 measured by laser or radar inside or outside the rotor blade 106 the deflection of prominent points, such as blade tip or special markings, of the rotor blade 106 is determined. In this type of measurement, local material differences have no influence on the measurement result, as the differences over the long measurement length are compensated.

2 shows a schematic representation of a device 102 for rotor blade adjustment for a wind turbine according to an embodiment of the invention. The wind turbine may be an embodiment of an in 1 shown wind turbine 100 act. The device 102 has an interface 220 for reading a plurality of sheet load signals 110 on. A leaf load signal 110 represents an average load per rotor blade during a rotation of the rotor. Furthermore, the device 102 An institution 222 for determining a plurality of correction angles 224 for a pitch angle per rotor blade. The device 222 for determining is formed, the plurality of correction angles 224 using the plurality of blade load signal 110 to investigate.

In the in 2 embodiment shown, the device comprises 102 furthermore an optional device 226 determining an aerodynamic imbalance. Here is the device 226 configured to determine the aerodynamic imbalance using the plurality of blade load signals. When the device 102 the device 226 of determining, so is the device 222 designed to determine to determine the plurality of correction angles for the pitch angle per rotor blade using the aerodynamic imbalance.

In one embodiment, the device comprises 102 an optional output interface 228 for providing a correction signal 230 , The correction signal 230 is determined using the plurality of correction angles 224 provided. Alternatively, the output interface 228 formed, a plurality of correction signals 230 in this case, a correction signal 230 a correction angle 224 is assigned for a pitch angle of a rotor blade.

In one embodiment, the interface is 220 trained for reading, information about a wind speed 116 and information about the actual performance 232 read. Another device 234 for determining, a power quotient q is constructed using the information about the actual power 232 as well as the information about the wind speed 116 to investigate. An optimization device 236 for optimizing is formed, the aforementioned devices, such as the interface 220 for reading, the device 226 for determining the device 222 for determining and the further device 234 to be addressed repeatedly for determination and via the output interface 228 the corresponding correction signal 230 or the corresponding plurality of correction signals 230 issue. The load changes per rotor blade resulting from an adjustment of the pitch angle of the plurality of rotor blades are transmitted via the interface 220 for reading in as a load signal 110 read in and on redetermining the correction angle 224 considered. This creates an optimization cycle that optimizes the performance quotient q. As a result, a power of the wind power plant is advantageously maximized in a partial load range, so that the economic efficiency of the wind turbine is optimized.

Optional is the interface 220 designed to read in to read in information about a performance of another wind turbine. In this case, it is convenient if the device 222 is designed for determining the plurality of correction angles 224 using the information about the performance of the other wind turbine to determine.

In the 2 shown device 102 has an optional averaging device 238 to averaging that is trained over the interface 220 read signals over a predefined time for averaging and as averaged signals to the downstream device 222 for determining or further device 234 to provide for detection so that they are processed in place of the un-mean signals.

In one embodiment of the device 102 For rotor blade adjustment, two subcomponents or two aspects can be distinguished: balancing the different aerodynamic properties and maximizing the yield in the partial load range.

For determining a balance of the different aerodynamic properties, for each rotor blade the mean blade deflection in the direction of impact during one rotor revolution is determined, or alternatively the average blade load during one rotor revolution. Then the average load of the three rotor blades is compared. The pitch angles of the rotor blades are then corrected by small offsets to equalize the mean blade load of the three blades. This is possible through online optimization. The offsets are calculated so that the sum of the offsets is zero, so that the pitch angle averaged over the three rotor blades does not change.

The behavior of the device 102 to the rotor blade adjustment to compensate for the different aerodynamic properties of the rotor blades can be described by the following pseudo-code:
Initialize k (meaningful value adjusted to the measured load size).
Initialize pitchoffset P1 = 0; P2 = 0; P3 = 0;
Initialize O1_alt = 0;
Jump label X;
Mass medium load of the rotor blades M1, M2, M3 during one rotor revolution
Calculation average load of the three leaves:
M = (M1 + M2 + M3) / 3;
Calculate stress offsets:
O1 = M1 - M;
O2 = M2 - M;
O3 = M3 - M;
Reduce the step size at sign change.
IF sign (O1)! = Sign (O1_old): k = k / 2
O1_old = O1;
IF k <Threshold: Finish the optimization
Calculate new pitchoffsets
P1 = P1 + k · O1;
P2 = P2 + k · O2;
P3 = P3 + k × O3;
Add the calculated offsets to those specified by the operations management
Should pitch angles;
Jump to jump label X.

Example:

• P1 = P2 = P3 = 0;
• k = 0.01;

For the three rotor blades an average load is determined during a rotor revolution of 130, 80 and 90 (unit Nm at bending moment, m at blade deflection).

The mean stress is thus at M = (130 + 80 + 90) / 3 = 100;

The goal is now that all three rotor blades have the same load. For this purpose, the load offset is calculated for each rotor blade:
O1 = 130-100 = 30;
O2 = 80-100 = -20;
O3 = 90 - 100 = -10;

The pitch angle offsets are now calculated as:
P1 = P1 + k · O1 = 0.3;
P2 = P2 + k · O2 = -0.2;
P3 = P3 + k × O3 = -0.1;

That is, on rotor blade 1, the pitch angle is increased by 0.30, thereby reducing the load. On rotor blades 2 and 3, the pitch angle is reduced by 0.20 or 0.10 so that the load increases there. The sum over all pitch angle offsets is 0, so the three leaves remain at the same pitch angle on average. As a result, this correction has no influence on the management.

The optimization described here is to be considered as an example, other methods for determining the pitch offsets are possible. The pitch offsets thus found completely correct the aerodynamic differences caused by the different rotor blade geometries. For example, the program described with the aid of the pseudo-code may be run through daily or operated continuously, in which case a lower limit for k must be set and k should be increased again if very large offsets occur. Due to the regular or continuous operation also changes in the aerodynamic properties can be compensated by ice accumulation or leaf aging.

In order to maximize the yield in the partial load range, an optimization of the pitch angle in the partial load range for a maximum yield is performed in one exemplary embodiment. For this purpose, the wind speed on the nacelle, the performance of the wind turbine and the average rotor blade load of the three blades are measured. These values are each averaged over a time interval, for example 10 minutes, then the quotient of average power and theoretical power is determined and this is maximized by varying the pitch angle by an optimizer.

• – Windgeschwindigkeit V (Gondelanemometer)
• – Leistung P

Berechne theoretische Leistung für jeden Tabelleneintrag:
P_theoretisch = n·v³ (Proportionalitätskonstante mal Windgeschwindigkeit hoch drei).
WENN Messintervall gültig (Anlage war durchgehend im Betrieb und immer im Teillastbereich):
Berechne mittlere Leistung Pm durch Mittelung der Tabelleneinträge.
Berechne mittlere theoretische Leistung Ptm durch Mittelung der Tabelleneinträge.
Berechne Quotient q = Pm/Ptm;
WENN q > q_alt:
P = P + pStep; % weiter in die gleiche Richtung
q_alt = q;
WENN q < q_alt:
P = P – pStep; % zurück zum letzten, besseren Wert
pStep = –pStep/2; % Schrittweite halbieren, Richtung ändern
P = P + pStep; % andere Richtung mit kleinerer Schrittweite testen
WENN pStep < 0,001: Optimierung beendet. The behavior of the device 102 to the rotor blade adjustment to maximize the yield in the partial load range can be described by the following pseudo-code:
Initialize P = 0;
Initialize pStep = 0.1;
Initialize q_alt = 0;
Measurement over time interval, for example 10 minutes, and storage in table:

• - wind speed V (gondola anemometer)
• - Power P

Calculate theoretical power for each table entry:
P_theoretical = n · v ³ (proportionality constant times wind speed high three).
IF measuring interval is valid (system was continuously in operation and always in the partial load range):
Calculate mean power Pm by averaging the table entries.
Calculate mean theoretical power Ptm by averaging the table entries.
Calculate quotient q = Pm / Ptm;
IF q> q_old:
P = P + p Step; % continue in the same direction
q_old = q;
IF q <q_old:
P = P - pStep; % back to the last, better value
pStep = -pStep / 2; Halve% step size, change direction
P = P + p Step; % test other direction with smaller increment
IF pStep <0,001: optimization finished.

Add P to the target pitch angle given by the operations management on all three rotor blades and start measuring again.

A program described by the above pseudo-code implements the so-called hill-climbing algorithm. It can be improved by not only using performance as an optimization target, but also maximizing blade loading and hence aerodynamic forces in the part-load range. In addition, it is possible to include further data in the optimization, for example, the measurement of wind speed before installation by LIDAR or a measuring mast. The power at neighboring wind turbine plants can also be included in the calculation. Averaging over long time intervals (eg, 5 to 10 minutes) averages out the short term impact of turbulence and gusts. The measured wind speed on the nacelle is affected by the influence of the rotor error. However, the theoretical power calculated from this must not be correct in terms of the absolute value, since it serves only as a basis for comparison and the algorithm maximizes the quotient of actual power to theoretical power. This program should also be run regularly.

3 shows a detailed view of a rotor 104 a wind turbine according to an embodiment of the invention. The wind turbine may be an embodiment of an in 1 described wind turbine 100 act. The rotor 104 has three rotor blades 106 on. A rotor blade 106 is shown in a sectional view, so the pitch angle 112 becomes clear. From the two other rotor blades 106 In essence, the leaf root is shown. The three rotor blades 106 are with a hub of the rotor 104 connected.

4 shows a representation of strain gauges 440 in the area of a blade root of a rotor blade 106 a wind turbine according to an embodiment of the invention. The wind turbine may be an embodiment of an in 1 described wind turbine 100 act. 4 shows in a sectional view through the blade root of the rotor blade 106 a look inside the rotor blade 106 from its blade root to the tip of the rotor blade 106 , On an inner wall of the rotor blade 106 are strain gauges 440 arranged. Here are in 4 clearly visible strain gauges at two points offset by 90 ° 440 arranged. In the other two quadrants are strain gauges 440 to divine. At the strain gauges 440 it is a variant of an in 1 described sensor 108 which is formed, a sheet load signal 110 or to provide a signal representative of the latter.

In one embodiment, target pitch angles with constant offsets (or temporally slowly varying offsets) are sent to the pitch drives of the rotor blades.

5 shows a detailed representation of a rotor blade 106 a wind turbine with a measurement of a blade deflection according to an embodiment of the invention. The wind turbine may be an embodiment of an in 1 described wind turbine 100 act. At a blade root of the rotor blade 106 is a laser 542 arranged. Inside the rotor blade 106 is a reflection wedge on a surface 544 arranged. In 5 is not shown a corresponding receiving device, which is formed, the reflection of one of the laser 542 in the direction of the reflection wedge 544 radiated laser beam to receive and to detect the distance from the laser to the point of impact on the wedge. This distance changes depending on the sheet deflection and thus represents a sheet load signal.

The blade angle difference between the rotor blades can be optically measured. The downward-pointing rotor blade is photographed from the base of the tower and then the pitch angle of the blade tip is determined. This measurement can be carried out for all three rotor blades. Then, the difference in the pitch angle can be compensated by the rotor blades are released and mounted twisted by the corresponding differences. Alternatively, the calculated differences can also be stored in the operational management of the wind turbine and taken into account in the calculation of the desired pitch angle. This procedure adjusts the pitch angle of the blade tips. Advantageously, the difference in the pitch angle of the individual rotor blades during operation using the in 2 described device 102 customized.

6 shows a flowchart of a method for rotor blade adjustment for a wind turbine according to an embodiment of the invention. The wind turbine may be an embodiment of an in 1 described wind turbine 100 act. The wind turbine comprises a rotor with a plurality of rotor blades. Depending on the embodiment, the rotor blade adjustment method includes a different number of steps, as described below. Thereby forming a step 610 of reading in and one step 620 determining a core of the presented embodiment. In step 610 When reading, a plurality of sheet load signals are read. In this case, the plurality of blade load signals represents an average load per rotor blade of the plurality of rotor blades during a rotation. In step 620 determining, determining a plurality of correction angles for a pitch angle per rotor blade of the plurality of rotor blades using the plurality of blade load signals.

As shown in the previous embodiments, it is in the step 610 the read-in sheet load signals are signals which are determined using a strain gauge, an optical sensor or an inertial sensor.

Optionally, the method includes a step 620 the preliminary step of determining 630 determining, wherein an aerodynamic imbalance is determined using the plurality of blade load signals. If the procedure for rotor blade adjustment the step 630 of determining, in step 620 determining the plurality of pitch angle correction angles using the aerodynamic imbalance.

The method optionally includes a step 640 providing a correction signal, wherein the correction signal is determined using the plurality of correction angles. The correction signal represents the plurality of correction angles. The correction signal is adapted to adjust the plurality of rotor blades of the wind turbine.

In a favorable embodiment, the method has a further step 650 determining as well as a step 660 of optimizing. It is in the step 610 read in the information about a wind speed and additionally or alternatively read in information about an actual power of the wind turbine. In the next step 650 determining, a power quotient is determined using the information about the actual performance of the wind turbine and the information about the wind speed. In step 640 of providing, the correction signal is provided using the power quotient. The performance quotient is suitable for adjusting the correction signal or the plurality of correction angles such that optimal performance of the wind turbine is achieved even in a partial load operation by sequentially varying a pitch angle offset and repeatedly executing the method. In step 660 optimizing, the steps of the rotor blade adjustment procedure are repeatedly executed until the power quotient falls below a predefined threshold. In this case, the predefined threshold value of the type is selected such that a compromise is achieved between a running time of the method with the step of optimizing and optimum performance.

In an optional step 670 the means become those in the step 610 the read-in plurality of sheet load signals are averaged to obtain a plurality of averaged sheet load signals. When in step 610 read in information about the wind speed and information about the actual performance of the wind turbine are read in step 670 averaging the wind speed information and the actual power information over a pre-defined time interval to obtain an average wind speed information and averaged wind turbine real power information. In the following step 630 determining, the aerodynamic imbalance is determined using the plurality of averaged blade load signals. In the following step 620 determining and additionally or alternatively the further step 650 determining, using the plurality of averaged blade load signals and additionally or alternatively the information about the average wind speed and additionally or alternatively the information about an average actual power, the plurality of correction angles and additionally or alternatively the performance quotient are determined.

In a particular embodiment is in step 610 read in the information about at least one power at least another wind turbine and read in the step 620 determining the plurality of correction angles using the information about the performance of the at least one further wind turbine.

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

LIST OF REFERENCE NUMBERS

100

Wind turbine

102

Device for rotor blade adjustment

104

rotor

106

rotor blade

108

sensor

110

Journal load signal

112

pitch angle

114

wind sensor

116

wind speed

220

Interface for reading

222

Device for determining

224

correction angle

226

Device for determining

228

Output interface

230

correction signal

232

actual performance

234

further means for determining

236

optimizer

238

Averaging means

440

Strain

542

laser

544

reflectorized wedge

610

Step of reading in

620

Step of determining

630

Step of determining

640

Step of providing

650

further step of determining

660

Step of optimizing

670

Step of averaging

Claims (11)

Rotor blade adjustment method for a wind turbine ( 100 ), which has a rotor ( 104 ) with a plurality of rotor blades ( 106 ), the method comprising the steps of: reading in ( 610 ) a plurality of leaf load signals ( 110 ); and determining ( 620 ) a plurality of correction angles ( 224 ) for a pitch angle ( 112 ) per rotor blade ( 106 ) of the plurality of rotor blades ( 106 ) using the plurality of leaf load signals ( 110 ). A method according to claim 1, wherein in step ( 610 ) of the read-in plurality of leaf load signals ( 110 ) using one signal each of at least one strain gauge ( 440 ) and / or an optical sensor ( 542 ) and / or an inertial sensor per rotor blade ( 106 ) is determined. Method according to one of the preceding claims, in which the 610 ) of the read-in plurality of leaf load signals ( 110 ) an average load per rotor blade ( 106 ) of the plurality of rotor blades ( 106 ) during at least one rotation of the rotor ( 104 ). Method according to one of the preceding claims, with a step ( 620 ) of determining step ( 630 ) of determining an aerodynamic imbalance using the plurality of blade load signals ( 110 ), wherein in step ( 620 ) of determining the plurality of correction angles ( 224 ) for the pitch angle ( 112 ) per rotor blade ( 106 ) using the aerodynamic imbalance to reduce the aerodynamic imbalance. Method according to one of the preceding claims, with a step ( 640 ) of providing a correction signal ( 230 ) using the plurality of correction angles ( 224 ) to the plurality of rotor blades ( 106 ). Method according to claim 5, wherein in step ( 610 ) of the read-in information about a wind speed ( 116 ) and information about actual performance ( 232 ) of the wind turbine ( 100 ) and in a further step ( 650 ) of the determination using the information about the actual performance ( 232 ) of the wind turbine ( 100 ) and the information about the wind speed ( 116 ) a performance quotient (q) is determined, and in the step ( 640 ) of providing the correction signal ( 230 ) is provided using the performance quotient (q), and in one step ( 660 ) of optimizing at least the step ( 610 ) of the reading, the further step ( 650 ) of determining and the step ( 640 ) of the supply until the power quotient (q) falls below a threshold value. Method according to one of the preceding claims, with a step ( 670 ) the means used in step ( 610 ) of the read-in plurality of leaf load signals ( 110 ) to obtain a plurality of averaged sheet load signals and / or means for information about the wind speed ( 116 ) and the information about the actual performance ( 232 ) of the wind turbine ( 100 ) to obtain an average wind speed information and an average actual power information, the following step ( 620 ) of determining and / or the further step ( 650 ) of determining using the plurality of averaged sheet load signals and / or the information on an average wind speed and / or the information on an average actual power, the plurality of correction angles ( 224 ) and / or the performance quotient (q). Method according to one of the preceding claims, in which in step ( 610 ) of reading information about a power of another wind turbine, wherein in step ( 620 ) of determining the plurality of correction angles ( 224 ) is determined using the information about the performance of the other wind turbine.  Apparatus adapted to perform all the steps of a method according to any one of the preceding claims.  Computer program adapted to perform all the steps of a method according to any one of the preceding claims.  A machine-readable storage medium having a computer program stored thereon according to claim 10.

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