METHOD FOR DETERMINING A WIND SPEED IN THE REGION OF A WIND TURBINE, AND A WIND TURBINE FOR PERFORMING THE METHOD

Abstract

A method of determining a corrected wind speed in the region of a wind turbine including the steps of measuring a wind speed in the region of a wind turbine, determining a force exerted on at least one rotor blade by the wind, determining a wind speed difference value which is dependent on the determined force and determining a corrected wind speed by correcting the measured wind speed in dependence on the wind speed difference value.

A wind turbine for carrying out the method.

Claims

1. A method of determining a corrected wind speed in a region of a wind turbine, the method comprising: measuring a wind speed in the region of a wind turbine, determining a force exerted on at least one rotor blade from wind, determining a wind speed difference value, wherein the wind speed difference value depends on the determined force, and determining a corrected wind speed by correcting the measured wind speed in dependence on the wind speed difference value.

2. The method as claimed in claim 1 wherein measuring the wind speed comprises measuring the wind speed at a first distance windward of the wind turbine or at a first position, and wherein determining the wind speed difference value is determined in dependence on the first distance or the first position.

3. The method as claimed in claim 1 further comprising establishing a second distance at the windward side of the wind turbine or a second position at which the corrected wind speed is to be determined, and wherein determining the wind speed difference value is determined in dependence on the second distance or the second position.

4. The method as claimed in claim 3 wherein the second distance is a windward distance or the second position is in a region outside a near field region of the wind turbine.

5. The method as claimed in claim 4 wherein the first distance is defined as a distance within the near field region of the wind turbine or the first position is defined as a position which is within the near field region.

6. The method as claimed in claim 1 wherein measuring the wind speed comprises using a lidar system to measure the wind speed.

7. The method as claimed in claim 4 wherein determining the corrected wind speed outside the near field comprises using a table or function with the corrected wind speed value and the corresponding measured wind speed.

8. A method as claimed in claim 1 wherein the wind speed difference value is determined in dependence on the determined force being converted into the wind speed difference value by at least one stored function or at least one stored table.

9. The method as claimed in claim 1 wherein determining the wind speed difference value further depends on the rotary speed and/or blade position.

10. The method as claimed in claim 1 wherein correcting the measured wind speed depends on the wind speed difference value being subtracted from or added to the measured wind speed.

11. The method as claimed in claim 1 wherein determining a force exerted on at least one rotor blade by the wind comprises using measurement values from at least one sensor arranged in or at at least one rotor blade, wherein the at least one sensor is a measuring device for detecting, extending, or compressing deformations.

12. The method as claimed in claim 11 further comprising: the at least one sensor for determining a force exerted on at least one rotor blade by the wind is calibrated before determining the force, and rotating the at least one rotor blade by moving the to a plurality of different positions, and repeating the steps of determining the force, determining the wind speed difference value, and determining a corrected wind speed at each position of the plurality of different positions.

13. The method as claimed in claim 1 comprising setting a torque by setting an exciter current of a generator of the wind turbine in dependence on the determined wind speed.

14. A wind turbine comprising circuitry and one or more sensors to carry out the method as claimed in claim 1.

15. The wind turbine as claimed in claim 14 wherein the one or more sensors includes a lidar system for measuring the wind speed and at least one sensor arranged in or on the at least one rotor blade for determining the force exerted on the at least one rotor blade by the wind.

16. The method as claimed in claim 4 wherein the near field region is defined as a region within a radius around the wind turbine, wherein the radius corresponds to a diameter of the rotor of the wind turbine.

17. The method as claimed in claim 4 wherein the near field region is defined as a region within a radius around the wind turbine, wherein the radius is at least two times the diameter of the rotor of the wind turbine.

18. The method as claimed in claim 5, wherein the first distance is a distance from the wind turbine chosen from at least one of the following: 40 meters, 60 meters, 90 meters, between 0 and 40 meters, between 40 and 60 meters, or between 60 and 90 meters.

19. The method as claimed in claim 11, wherein the at least one sensor includes at least one or more sensors chosen from a strain gauge, a pressure sensor, an optical pressure sensor, or a camera.

20. The method as claimed in claim 12, wherein the different positions include at least one position chosen from a 3 o'clock position, a 6 o'clock position, or a 9 o'clock position.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0032] Further embodiments are set forth by means of the configurations described by way of example in greater detail with reference to the Figures in which:

[0033] FIG. 1 shows a wind turbine, and

[0034] FIG. 2 shows the steps in the method.

DETAILED DESCRIPTION

[0035] FIG. 1 shows a diagrammatic view of a wind turbine according to an embodiment of the invention. The wind turbine 100 has a tower 102 and a nacelle 104 on the tower 102. Provided on the nacelle 104 is an aerodynamic rotor 106 having three rotor blades 108 and a spinner 110. In operation of the wind turbine the aerodynamic rotor 106 is caused to rotate by the wind and thus also rotates an electrodynamic rotor or rotor member of a generator which is directly or indirectly coupled to the aerodynamic rotor 106. The electric generator is disposed in the nacelle 104 and generates electrical energy. The pitch angles of the rotor blades 108 can be altered by pitch motors at the rotor blade roots 108b of the respective rotor blades 108.

[0036] The wind turbine 100 serves to carry out an embodiment of the method. For that purpose the wind turbine 100 has a lidar system 10 which is arranged in the spinner 110 and is adapted to determine wind speeds at the windward side 12 of the wind turbine 100. The lidar system 10 is preferably fixedly mounted, wherein determination of the wind speed at the windward side 12 is made possible by a yaw drive (not shown) tracking the nacelle 104 of the wind turbine 100 to the wind direction.

[0037] By way of example in FIG. 1 the wind speed is determined at a first position 14 in the near field region 16 of the wind turbine 100. The first position 14 is for example at a first distance 18 from the wind turbine 100 at the windward side 12. In accordance with the method, with the wind speed determined at the first position 14, it is possible to determine the wind speed at a second position 20 in the far field 22 of the wind turbine 100. For that purpose the second position 20 is at a second distance 24 at the windward side 12 of the wind turbine 100.

[0038] For determining the corrected wind speed in the second position 20 from the measured wind speed in the first position 14 the force exerted on the rotor blades 108 by the wind is determined by means of sensors 26 in the region of the blade roots 108b of the rotor blades 108. A wind speed difference value is determined on the basis of that force and the measured speed at the point 14 is corrected with the wind speed difference value.

[0039] FIG. 2 shows the steps in the method. In step 28 a wind speed is measured. For that purpose a first distance 18 is set, preset or predetermined. The wind speed which was measured at the first distance 18 is then output as a measured wind speed 30. In parallel or substantially at the same time a force is determined in step 32. In addition the current rotary speed 40 of the wind turbine is determined in a step 34 and the blade position 42 of the wind turbine is determined in a step 36.

[0040] The first distance 18, the determined force 38, the measured rotary speed 40 and the measured blade position 42 are passed to a step 44 for determining a wind speed difference value 48 as an input value. In the step 44 for determining a wind speed difference value 48 a second distance 24 is also predetermined as an input value, by which the corrected wind speed is to be determined. On the basis of the input values 18, 24, 38, 40, 42 the wind speed difference value 48 is determined by means of a function 46 and the wind speed difference value 48 is then output.

[0041] Together with the measured wind speed 30 the corrected wind speed 52 is then determined in a correction step 50. The corrected wind speed 52 is output after the correction and in a step 54 a torque of a generator of the wind turbine 100 is set in dependence on the corrected wind speed 52. Additionally or alternatively the corrected wind speed 52 at the second distance 24 is stored in a calibration table in a step 56. The calibration table can for example be later used to determine when speeds 52 at the second distance 24 even without determining the force 38, solely by measurement of the wind speed 30 at the first distance 18.

[0042] The sensors 26 are calibrated in an optional step 58 for determining the force in the step 32.