Method for ascertaining a wind direction at a wind power installation, system for ascertaining a wind direction, and a wind power installation

Abstract

A method for ascertaining a wind direction at a wind power installation having a rotor on which at least one rotor blade is arranged. The method includes measuring first wind speeds in a predefined first measuring direction and second wind speeds in a predefined second measuring direction different from the first measuring direction in each case with a measuring frequency at a measuring point for a measuring period, wherein the measuring period is defined by a rotational distance of the rotor or by a prespecified time, wherein the rotor blade or one of the rotor blades passes the measuring point in the measuring period, and determining a wind direction by vectorial evaluation of the first wind speeds and of the second wind speeds.

Claims

1. A method for determining a wind direction at a wind power installation having a rotor and at least one rotor blade arranged on the rotor, the method comprising: measuring first wind speeds in a predefined first measuring direction and second wind speeds in a predefined second measuring direction different from the predefined first measuring direction, wherein the measurements are made, in each case, with a measuring frequency at a measuring point for a measuring period, wherein the measuring period is defined by a rotational distance of the rotor or by a prespecified time at which the at least one rotor blade passes the measuring point in the measuring period; and determining a wind direction by vectorial evaluation of the first wind speeds and of the second wind speeds, wherein the vectorial evaluation of the first wind speeds and of the second wind speeds comprises determining a first average wind speed by averaging the first wind speeds, and determining a second average wind speed by averaging the second wind speeds, wherein the wind direction is determined by vectorial evaluation of the first average wind speed and of the second average wind speed, or wherein the vectorial evaluation of the first wind speeds and of the second wind speeds comprises determining wind vectors from the first wind speeds and the second wind speeds for the measuring period, wherein the wind direction is determined by vectorial evaluation of the wind vectors.

2. The method according to claim 1, wherein the measuring point is arranged on a nacelle of the wind power installation, wherein the measuring point is located on an upper portion of the nacelle in a vertical direction, and the measuring point is arranged substantially immovably on the nacelle.

3. The method according to claim 1, wherein the first wind speeds and the second wind speeds are measured with a two-dimensional anemometer.

4. The method according to claim 3, wherein the two-dimensional anemometer is a digital ultrasonic anemometer.

5. The method according to claim 1, wherein the predefined first measuring direction and the predefined second measuring direction are oriented orthogonally with respect to each other.

6. The method according to claim 1, wherein the predefined first measuring direction and the predefined second measuring direction are oriented substantially horizontally.

7. The method according to claim 1, wherein the measuring frequencies for the predefined first measuring direction and for the predefined second measuring direction are substantially identical.

8. The method according to claim 1, wherein: one of the first wind speeds and one of the second wind speeds are measured substantially isochronously; and/or there are at most 100 milliseconds between two respective measurements of the first wind speeds and two respective measurements of the second wind speeds; and/or the prespecified time of the measuring period is less than 10 seconds.

9. The method according claim 1, wherein the rotational distance of the rotor is between 115° and 125°.

10. The method according to claim 1, further comprising: adjusting the wind direction depending on a set pitch angle or an arising tip speed ratio, or both.

11. The method according to claim 1, further comprising producing a wind direction signal indicative of the wind direction, and weighting the wind direction signal with a weighting factor.

12. The method according to claim 1, further comprising determining an averaged average wind speed by scalar evaluation of the first wind speeds and of the second wind speeds.

13. The method according to claim 1, further comprising using an incremental sensor for sensing the rotor position.

14. The method according to claim 13, wherein an output signal of the incremental sensor triggers a measurement of the first wind speeds and of the second wind speeds.

15. The method according to claim 1, wherein the wind direction is determined at a predefined time interval, and, for the determination of the wind direction, a prespecified number of measurement values is taken into consideration, wherein each of the prespecified number of measurement values represent one of the first wind speeds and one of the second wind speeds.

16. The method according to claim 15, wherein the predefined time interval is 1 second.

17. A system for ascertaining a wind direction at a wind power installation having a rotor and at least one rotor blade arranged on the rotor, the system comprising: a wind sensor arranged at a measuring point and configured to measure first wind speeds in a predefined first measuring direction and to measure second wind speeds in a predefined second measuring direction different from the predefined first measuring direction for a measuring period, wherein the measuring period is defined by a rotational distance of the rotor or by a prespecified time, wherein the measuring period is selected in such a manner that the at least one rotor blade passes the measuring point in the measuring period; and a controller coupled to the wind sensor and configured to: receive signals indicative of measurements of the first and second wind speeds; and determine a wind direction by vectorial evaluation of the first wind speeds and the second wind speeds, wherein the vectorial evaluation of the first wind speeds and of the second wind speeds comprises determining a first average wind speed by averaging the first wind speeds, and determining a second average wind speed by averaging the second wind speeds, wherein the wind direction is determined by vectorial evaluation of the first average wind speed and of the second average wind speed.

18. A wind power installation comprising: a nacelle; a system according to claim 17, wherein the system is arranged on the nacelle; and wherein the rotor and the at least one rotor blade are arranged on the rotor.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) Preferred exemplary embodiments will be explained by way of example with reference to the attached figures, in which:

(2) FIG. 1 shows a schematic three-dimensional view of an exemplary embodiment of a wind power installation;

(3) FIG. 2 shows a schematic view of an exemplary embodiment of a wind-sensing unit;

(4) FIG. 3 shows schematic views of the wind-sensing unit shown in FIG. 2 at different wind speeds;

(5) FIG. 4 shows a schematic view of exemplary measurements of first and second wind speeds;

(6) FIG. 5 shows a schematic view of the wind-sensing unit shown in FIG. 2 with a first average wind speed and a second average wind speed and the wind direction resulting therefrom;

(7) FIG. 6 shows an exemplary diagram of first and second wind speeds and of a wind direction plotted above the rotor angle of rotation; and

(8) FIG. 7 shows a schematic method.

DETAILED DESCRIPTION

(9) In the figures, identical or substantially functionally identical or functionally similar elements are denoted by the same reference signs.

(10) FIG. 1 shows a schematic three-dimensional view of a wind power installation 100. The wind power installation 100 has a tower 102 and a nacelle 104 on the tower 102. An aerodynamic rotor 106 having three rotor blades 108 and a spinner 110 is provided on the nacelle 104. During operation of the wind power installation 100, the aerodynamic rotor 106 is caused to rotate by the wind and thus also rotates an electrodynamic rotor of a generator which is coupled directly or indirectly to the aerodynamic rotor 106. The electric generator is arranged in the nacelle 104 and generates electrical energy.

(11) The wind power installation 100 comprises a system 120 for ascertaining a wind direction. The system 120 comprises a wind-sensing unit 122 which is arranged at a measuring point 123. In one embodiment, the wind-sensing unit 122 comprises one or more wind sensors, such as anemometers. In one embodiment, the wind-sensing unit 122 is a two-dimensional wind senor or anemometer. In another embodiment, the wind-sensing unit 122 comprises two wind sensors, each arranged to measure wind from different directions as each other. In one embodiment, the wind directions are perpendicular from each other. The measuring point 123 or the wind-sensing unit 122 is arranged on the nacelle 104. In particular, the measuring point 123 or the wind-sensing unit 122 is located on an upper portion of the nacelle 104 in the vertical direction. The wind-sensing unit 122 is arranged substantially immovably on the nacelle 104. The wind-sensing unit 122 is configured for measuring first wind speeds in a predefined first measuring direction and second wind speeds in a predefined second measuring direction different from the first measuring direction. The first wind speeds and the second wind speeds are measured with the wind-sensing unit 122 in each case with a measuring frequency.

(12) The system 120 furthermore comprises a controller 124. The controller 124 is configured to attain first wind speeds and second wind speeds for a measuring period, wherein the measuring period is defined by a rotational distance of the rotor 106 or by a prespecified time, wherein the measuring period is selected in such a manner that the rotor blade 108 or one of the rotor blades 108 passes the measuring point 123 in the measuring period; that is, in the present case, one of the rotor blades passes or crosses the 0° position. Furthermore, the controller 124 is configured to determine a wind direction by vectorial evaluation of the first average wind speed and of the second average wind speed.

(13) Furthermore, the wind power installation comprises an incremental sensor 125, which can also be included by the system 120. An output signal of the incremental sensor 125 preferably triggers the ascertaining of the rotational distance and thus the beginning and end of the measuring period. The measurement of the first and of the second wind speed by the wind-sensing unit 122 can take place synchronously with the output signal of the incremental sensor 125 or independently thereof, for example in a buffer store.

(14) FIG. 2 shows a schematic view of an exemplary embodiment of a wind-sensing unit 122. The wind-sensing unit 122 has a first measuring direction x and a second measuring direction y. The wind-sensing unit 122 measures a wind speed in the first measuring direction x and in the second measuring direction y. The wind-sensing unit 122 is preferably configured in such a manner that it measures substantially no wind speed in a measuring direction that deviates from the first measuring direction x and/or from the second measuring direction y.

(15) FIG. 3 shows schematic views of the wind-sensing unit 122 shown in FIG. 2 with different wind speeds u.sub.1, u.sub.2, v.sub.1, v.sub.2. FIG. 3 in particular shows two different states in which different wind speeds are measured with the wind-sensing unit 122. In the state shown on the left in the image, a first wind speed u.sub.1 in a first measuring direction x is shown. Furthermore, it is shown here that a second wind speed v.sub.1 is present in a second measuring direction y at the wind-sensing unit 122. On the right in the image, the state is illustrated for a different time with a lower wind speed. It is apparent that the first wind speed u.sub.2 in the first measuring direction x and the second wind speed v.sub.2 in the second measuring direction y are lower than in the state shown on the left in the image. Should the wind blow precisely from the measuring direction x, the value u.sub.x would assume the wind speed of this wind and the value v.sub.y would be zero.

(16) For ascertaining a first and second average wind speed, which will be explained in more detail below, a plurality of first wind speeds U and second wind speeds V are taken into consideration.

(17) FIG. 4 shows a schematic view of exemplary measurements of first and second wind speeds. This principle for determining the average wind speeds is depicted here in FIG. 4. The wind-sensing unit 122 measures the first wind speeds u.sub.X in the first measuring direction x and the second wind speeds v.sub.y in the second measuring direction y, preferably at continuous intervals.

(18) In order to determine a first average wind speed, a measuring period ΔT is defined. The measurement values u.sub.1 to u.sub.n lying in the measuring period ΔT are averaged, for example, for the first wind speed u.sub.X in the first measuring direction x. For this purpose, said measurement values can be for example added up and divided by the number of measurement values being considered in order to obtain an arithmetic mean value. This takes place analogously with the measurement values of the wind speeds V.sub.1 to v.sub.N in the second measuring direction y. It is crucial here that a blade passage has taken place at the measuring point 123 in the measuring period ΔT such that the rotor blade 108 or one of the rotor blades 108 passes the measuring point 123 in the measuring period T.

(19) FIG. 5 shows a schematic view of the wind-sensing unit 122 shown in FIG. 2 with a first average wind speed U and a second average wind speed V and the wind direction W resulting therefrom. The first average wind speed V can be determined by averaging the first wind speeds u.sub.X. Analogously thereto, the second average wind speed U can be determined by averaging the second wind speeds v.sub.Y. The wind direction W can be determined by the value of the first average wind speed and the value of the second average wind speed and knowledge of the angle between the first measuring direction x and the second measuring direction y.

(20) FIG. 6 shows an exemplary diagram of first and second wind speeds and of a wind direction plotted above the rotor angle of rotation 200. The rotor angle of rotation 200 of the rotor 106 is plotted on the abscissa. From a reference point which is assigned the zero degree position, the rotor 106 rotates from 0 degrees towards 360 degrees. A speed deviation 202 is plotted in percent on the first ordinate, shown on the left, wherein, at a rotor angle of rotation 200 of 0 degrees, a reference point has been placed at 0. A wind direction deviation 204 is illustrated, likewise in percent, on the second ordinate, depicted on the right in the diagram.

(21) The curve 206 represents the wind speed deviation in the first measuring direction x. The curve 208 represents the speed deviation in the second measuring direction. The curve 210 represents the wind direction deviation. The measurement values are related to a measuring point 123, in particular a wind-sensing unit 122. It is apparent that the first and second wind speeds 206, 208 are subject to significant fluctuations along the angle of rotation 200. As a result, the wind direction 210 is also not constant, but rather changes by up to 45° during passage of a rotor blade.

(22) FIG. 7 shows a schematic method. In the first step 300, first wind speeds u.sub.x in a predefined first measuring direction x and a second wind speed v.sub.y in a predefined second measuring direction y different from the first measuring direction x are measured in each case with a measuring frequency at a measuring point 123. In step 302, a first average wind speed U is determined by averaging the first wind speeds u.sub.x.

(23) In step 304, a second average wind speed V is determined by averaging the second wind speeds v.sub.y. This takes place for a measuring period. The measuring period ΔT is defined by a rotational distance of the rotor 106 or by a prespecified time. During the measuring period ΔT, the rotor blade 108, or one of the rotor blades 108, passes the measuring point 123. In step 306, a wind direction W is determined by vectorial evaluation of the first average wind speed U and of the second average wind speed V.

REFERENCE SIGNS

(24) 1 Blade passage 100 Wind power installation 102 Tower 104 Nacelle 106 Rotor 108 Rotor blades 110 Spinner 120 System for ascertaining a wind direction 122 Wind-sensing unit 123 Measuring point 124 Controller 125 Incremental sensor 200 Angle of rotation 202 Speed deviation in % 204 Wind direction 206 Wind speed in first measuring direction 208 Wind speed in second measuring direction 210 Wind direction U First average wind speed u.sub.x First wind speed in first measuring direction x V Second average wind speed v.sub.y Second wind speed in second measuring direction y W Wind direction x first measuring direction y second measuring direction ΔT Measuring period

(25) The various embodiments described above can be combined to provide further embodiments. These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.