Method for determining the orientation of an engine nacelle

Abstract

A method for determining the orientation of a nacelle of a wind turbine, wherein the nacelle carries a Global Navigation Satellite System (GNSS) sensor, the method comprising: yawing the nacelle between a series of orientations; obtaining trajectory data based on a series of calibration positions measured by the GNSS sensor, wherein each calibration position is measured by the GNSS sensor when the nacelle is in a respective one of the series of orientations; storing the trajectory data; after storing the trajectory data, measuring a new position with the GNSS sensor; and determining the orientation of the nacelle based on the stored trajectory data and the new position.

Description

Technical Field

[0001] The present invention relates to a method for determining the orientation of a nacelle. Background Art

[0002] Determining the orientation of the nacelle of a wind turbine (e.g., relative to true (geographical) north) can be important for a variety of reasons. First, since the nacelle generally points into the wind, its orientation can be used as an indication of the wind direction. This indication can be used to analyze the performance of the wind turbine. For example, a wind turbine may not produce as much power as expected for a given wind intensity because it is in the wake of another wind turbine. Thus, if the wind direction is known, this suboptimal performance can be taken into account. Alternatively, the wind direction can be used to modify the operation of the wind turbine. For example, it is known that if the wind comes from a certain direction, a large amount of wind shear is expected, and thus the wind turbine is derated.

[0003] The orientation of a wind turbine can be determined manually, for example, by standing at a certain distance behind the turbine in a straight line with the nacelle and then measuring the apparent direction of the wind turbine with a compass. Then, this orientation measurement must be corrected from magnetic north to true (geographical) north before it is manually input into the control system of the wind turbine. This method is prone to human error. Summary of the Invention

[0004] A first aspect of the present invention provides a method for determining the orientation of a nacelle of a wind turbine, wherein the nacelle carries a Global Navigation Satellite System (GNSS) sensor, the method comprising: yawing the nacelle between a series of orientations; obtaining trajectory data based on a series of calibration positions measured by the GNSS sensor, wherein each calibration position is measured by the GNSS sensor when the nacelle is in a corresponding orientation of the series of orientations; storing the trajectory data; after storing the trajectory data, measuring a new position with the GNSS sensor; and determining the orientation of the nacelle based on the stored trajectory data and the new position.

[0005] Determining the orientation of the nacelle may include identifying the position in the trajectory data that is closest to the new position; and identifying the orientation of the nacelle corresponding to the identified position. The identified position in the trajectory data can be one of the calibration positions measured by the GNSS sensor, or some other position recorded by the trajectory data. The trajectory data can be stored as a look-up table that enables the orientation of the nacelle to be looked up based on the identified position.

[0006] The GNSS sensor can move on a circle centered on the yaw axis, and the trajectory data can indicate the position of the yaw axis. For example, the trajectory data can include the position coordinates of the yaw axis or be constituted by the position coordinates of the yaw axis.

[0007] The stored trajectory data may define a reference frame, and the new position may be transformed into that reference frame and then used to determine the orientation of the nacelle by triangulation.

[0008] The trajectory data may include verification of calibration positions, or geometric functions (such as circles) based on the calibration positions.

[0009] The trajectory data may include multiple sets of trajectory data, each set corresponding to a different level of thrust experienced by the wind turbine. For example, each set of trajectory data may include a look-up table (or part of a look-up table) that contains a set of calibration positions corresponding to the respective thrust level.

[0010] Each set of trajectory data may be obtained by yawing the nacelle between a series of orientations, where the wind turbine experiences the respective one of the different levels of thrust; and obtaining the set of trajectory data based on a series of calibration positions measured by a GNSS sensor.

[0011] The orientation of the nacelle may be determined by: selecting one of the sets of trajectory data based on the new position, and determining the orientation of the nacelle based on the selected one of the sets of trajectory data.

[0012] The method may further include the steps of: determining a correction angle associated with the position of the GNSS sensor on the nacelle; and determining the orientation of the nacelle based on the correction angle.

[0013] The correction angle may be determined by: using an accelerometer to determine the vibration direction of the wind turbine, and determining the correction angle based on the vibration direction.

[0014] The orientation of the nacelle may be determined based on the known position of the sensor on the nacelle. The known position of the sensor on the nacelle may be obtained by measurement or by design. For example, by designing the sensor to be positioned at the center of the nacelle, the sensor may be known. Alternatively, the position of the sensor on the nacelle may be obtained by: orientation measurement, or by using an accelerometer to determine the vibration direction of the wind turbine and determining the angular position of the sensor on the nacelle based on the vibration direction.

[0015] The calibration positions and the new position may be measured by a GNSS sensor relative to a satellite constellation and a ground reference module.

[0016] The nacelle may carry multiple Global Navigation Satellite System (GNSS) sensors, trajectory data may be obtained based on a series of calibration positions measured by the GNSS sensors, where each calibration position is measured by the GNSS sensors when the nacelle is in the respective one of a series of orientations; the GNSS sensors may each measure a respective new position; and the orientation of the nacelle may be determined based on the stored trajectory data and the new positions of the GNSS sensors.

[0017] The orientation of the nacelle determined by this method can be a geographical bearing (e.g., a bearing relative to geographical or true north).

[0018] According to another aspect of the invention, there is provided a wind turbine comprising: a tower; a nacelle rotatably mounted on the tower; a Global Navigation Satellite System (GNSS) sensor carried by the nacelle; and a control system configured to: yaw the nacelle between a series of orientations; obtain trajectory data based on a series of calibration positions measured by the GNSS sensor, wherein each calibration position is measured by the GNSS sensor when the nacelle is in a corresponding one of the series of orientations; store the trajectory data; after storing the trajectory data, measure a new position using the GNSS sensor; and determine the orientation of the nacelle based on the stored trajectory data and the new position.

[0019] The control system can be configured to determine the orientation of the nacelle by the method according to the first aspect of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Embodiments of the invention will now be described with reference to the drawings, in which:

[0021] Figure 1 a wind turbine is shown;

[0022] Figure 2A a top view of a nacelle according to one embodiment is shown;

[0023] Figure 2B how to determine the orientation of the nacelle is shown;

[0024] Figure 3A a GNSS sensor offset from the nacelle center plane is shown;

[0025] Figure 3B how a correction angle can be measured is shown;

[0026] Figure 3C how to use the correction angle to correct the measurement of the nacelle orientation is shown;

[0027] Figure 4 a nacelle experiencing thrust is shown Figure 1 in a top view;

[0028] Figure 5 a top view of a nacelle according to another embodiment is shown;

[0029] Figure 6 a top view of a nacelle according to yet another embodiment is shown; and

[0030] Figure 7 a top view of a nacelle according to yet another embodiment is shown. Detailed implementation mode

[0031] Figure 1 The wind turbine 1 is shown. The wind turbine 1 has a tower 2 and a nacelle 3 located at the top of the tower 2. The wind turbine rotor 4 is connected to the nacelle 3 and is arranged to rotate relative to the nacelle 3. The wind turbine rotor 4 includes a wind turbine hub 5 and a plurality of wind turbine blades 6 extending from the hub 5. Although a wind turbine rotor 4 with three blades 6 is shown, different numbers of blades, such as two or four, can be used.

[0032] Figure 2A The nacelle 3 and the wind turbine blades 6 are shown from a top-down perspective. The nacelle 3 can be rotated by a yaw drive system 11 so that it yaws relative to the tower 2 about a vertical yaw axis 12. The nacelle 3 can yaw through a full 360°.

[0033] The nacelle 3 carries a GNSS sensor 14. The GNSS sensor 14 can be mounted on the top of the nacelle (e.g., on top of the cooler). Alternatively, the GNSS sensor 14 can be held by an arm extending from the nacelle, or it can be supported by any other part of the wind turbine that rotates with the nacelle when the nacelle yaws.

[0034] The GNSS sensor 14 is a position sensor that uses one or more global navigation satellite systems (such as GPS, Galileo, GLONASS, Beidou) to determine its position. When the nacelle 3 yaws, the position of the GNSS sensor 14 changes because the GNSS sensor 14 is offset from the yaw axis 12. The GNSS sensor 14 can measure its position with centimeter accuracy. The position can be recorded as a set of coordinates, such as (longitude, latitude), (x, y), or (r, θ).

[0035] The GNSS sensor 14 uses a satellite constellation to determine its position. Optionally, the sensor 14 can use a ground real-time kinematic (RTK) base module to improve the accuracy of its position measurement. This RTK module can be shared among multiple wind turbines in a wind farm.

[0036] In Figure 1 the control system 10 of the wind turbine is shown at 10. In this case, the control system 10 is located at the base of the tower, but it can be located at any other position (e.g., in the nacelle), or the control system 10 can be distributed over different parts of the wind turbine. The control system 10 is connected to the yaw drive system 11 and the GNSS sensor 14. The control system 10 is configured to determine the orientation of the nacelle of the wind turbine by the method described below.

[0037] The control system 10 guides the yaw drive system 11 to yaw the nacelle 3 between a series of orientation or yaw angles and performs calibrated position measurements for each orientation. This can be done in a separate calibration routine before the turbine starts operating and generating power. For example, before a wind turbine starts operating, it is common to perform a cable twist check, where the nacelle is yawed through a series of rotations to twist the cable until the safety mechanism is triggered, and then the nacelle is deflected back to untwist the cable. The main purpose of the cable twist check is to check the safety mechanism, but optionally, calibrated position measurements can be taken during such a cable twist check. This can provide a large set of calibrated position measurements, such as 5 turns in one direction and 5 turns in the opposite direction. Alternatively, the calibrated position measurements can be taken during the initial phase of the operating life of the wind turbine (e.g., during the first year when it is expected to point in many directions). In this case, the calibrated position measurements may not be available for all directions, but sufficient measurements are possible.

[0038] The series of orientations associated with the calibrated position measurements can have an approximately equal distribution over the entire 360° rotation. In each orientation, the nacelle 3 faces a different direction. At the time shown in Figure 2A , the nacelle 3 is in its orientation facing true north (i.e., geographic north). For each orientation, the GNSS sensor 14 is in a different position. At each orientation, the GNSS sensor 14 measures the corresponding calibrated position.

[0039] The control system 10 obtains and stores trajectory data based on a series of calibrated positions (corresponding to a series of orientations). For example, the trajectory data can include a check of the calibrated position measurements. Thus, in the case of Figure 2A , if the position of the GNSS sensor 14 is recorded in Cartesian (x, y) coordinates, the calibrated position measurement when the nacelle points north can be (0, -1). The trajectory data indicates the trajectory (in this case, the circle 16) traveled by the GNSS sensor 14 as it yaws between a series of orientations.

[0040] Rather than storing the trajectory data as a check of the unprocessed calibrated position measurements, the position calibration measurements can be processed so that the trajectory data is stored in some other way, such as as a geometric function or simply as the coordinates of the center of the circle 16 (which is also the position of the yaw axis 12).

[0041] After the trajectory data has been stored as described above, the stored trajectory data can be used to determine the orientation of the nacelle of the wind turbine. Thus, a new position (x1, y1) can be measured with the GNSS sensor 14; and the orientation of the nacelle can be determined based on the stored trajectory data and the new position. For example, if the new position (x1, y1) is (0.707, -0.707), the trajectory data can indicate that the nacelle orientation is northwest. The expected accuracy is within 1 degree.

[0042] Figure 2B More particularly shows how the nacelle orientation is determined. Position 14a indicates the position of the GNSS sensor 14 when the nacelle points north (corresponding to Figure 2A ). Since the GNSS sensor 14 is mounted centrally on the nacelle, this position 14a is due south of the yaw axis 12. Thus, the line 15 from position 14a to the yaw axis 12 extends in the north-south direction.

[0043] The nacelle has yawed counterclockwise by 45°, so it now points northwest, and the GNSS sensor 14 has moved to the new position (x1, y1) shown in Figure 2B . The line 17 from the new position (x1, y1) to the yaw axis 12 extends at an angle of 45° to the north-south direction 15. Thus, by constructing the line 17 and measuring the angle relative to the north-south direction 15, the nacelle orientation can be obtained.

[0044] When the nacelle points north, the position of the GNSS sensor 14 can be obtained in a variety of ways.

[0045] Preferably, the orientation of the nacelle is determined based on the known position of the sensors on the nacelle. The known position of the sensors on the nacelle can be obtained by measurement or by design, as described in the various examples below.

[0046] In a first example, if the GNSS sensor 14 is designed to be mounted accurately centrally (on the central plane 7 of the nacelle), it can be assumed that it is due south of the yaw axis 12 when the nacelle points north.

[0047] It may not be possible to mount the GNSS sensor 14 centrally on the nacelle because other equipment must be placed at that central location. Thus, in other examples, the GNSS sensor 14 is not mounted on the central plane 7, but its position on the nacelle is still known. Thus, when the nacelle points north, the position of the GNSS sensor 14 can be obtained based on its known position on the nacelle.

[0048] For example, the operator can manually measure the distance d1 from the yaw axis 12 to the GNSS sensor and the distance d2 from the GNSS sensor to the central plane 7 of the nacelle, and enter the distances d1, d2 into the controller. Then, the angular position of the sensor on the nacelle (i.e., the angle d1d3) can be obtained from the distances d1 and d2 by trigonometry. Alternatively, the distances d1, d2 can be known by design. Alternatively, there can be two or more possible positions, and the distances d1, d2 for each position are known. In this case, it is simply necessary to enter the position among the possible positions occupied by the sensor into the controller. Or, the distance d2 can be known (by measurement or design), but the distance d1 can be unknown. In this case, the distance d3 from the sensor 14 to the yaw axis 12 can be determined by analyzing the calibration position measurements to obtain the radius of the circle 16 (which is the distance d3). Then, the angular position of the sensor (the angle d1d3) can be obtained by trigonometry based on the distances d2 and d3.

[0049] In all of the above examples, no calibration measurements of the orientation of the nacelle are required because the GNSS sensor 14 can use satellites to determine the north-south direction. In other words, the north-south direction is inherently known to the GNSS system.

[0050] If the position of the GNSS sensor 14 relative to the nacelle is unknown, one or more calibration measurements of the orientation of the nacelle may be required. For example, the nacelle can be yawed until it points north, and the (x, y) position of the sensor is measured. Alternatively, a compass can be used to measure the orientation of the nacelle, and this orientation measurement is associated with a specific (x, y) position measurement of the GNSS sensor 14. Then, the line 15 can be obtained. For example, referring to Figure 2B , if the nacelle points west, the GNSS sensor will be at position 14b. Measure the orientation of the nacelle (90° in this case) and the position of the sensor (in this case, (1, 0)). Now, the direction of the line 15 can be obtained by moving 90° around the circle. This type of calibration process is not preferred because it is prone to human error.

[0051] In the above example, the orientation of the nacelle is obtained by calculating the (x, y) coordinates of the yaw axis 12 and the direction of the line 15 based on the new position (x1, y1). In this case, if the GNSS sensor 14 is accurately and centrally mounted on the nacelle, the trajectory data can consist only of the coordinates of the yaw axis 12 at the center of the circle, and no other information is required. Alternatively, the stored trajectory data can also include calibration measurements of the orientation of the nacelle as described above, and / or the position of the sensor on the nacelle (e.g., the distance d2, the distances d1 and d2, the angle d1d3, or any other data that can be used to infer the position of the GNSS sensor 14 when the nacelle points north).

[0052] In another example, the stored trajectory data can simply define the origin and orientation of the reference frame based on the known position of the yaw axis 12 and the position of the GNSS sensor 14 when the nacelle is pointing north. In other words, the reference frame can be defined such that the yaw axis 12 is at coordinates (0, 0), and the position of the GNSS sensor 14 when the nacelle is pointing north is at coordinates (1, 0). Thus, the orientation of the nacelle can be determined simply by triangulation based on the coordinates (x1, y1) of the GNSS sensor 14 at the new position. For example, if the new position is (x1, y1), the orientation of the nacelle can be obtained by triangulation as tan -1 (x1 / y1).

[0053] The above examples rely on the assumption that the trajectory of the GNSS sensor 14 during the calibration routine is a circle 16 centered on the yaw axis 12. In another example, the trajectory data can include a look-up table having a series of calibration position measurements (in any reference frame) and the nacelle orientation associated with each calibration position measurement. This method does not rely on the assumption that the trajectory of the GNSS sensor 14 during the calibration routine is a circle 16 centered on the yaw axis 12.

[0054] A basic example of such a look-up table is shown in Table 1 below:

[0055] Table 1

[0056] Calibration position measurement Cabinet orientation (0,-1) North (0,1) South (-1,0) East (1,0) West

[0057] In this case, instead of determining the nacelle orientation by calculation, it is determined by identifying the position in the trajectory data that is closest to the new position; and using the look-up table to retrieve the nacelle orientation corresponding to the identified position.

[0058] The sensor 14 can be mounted anywhere as long as it rotates with the nacelle. In Figure 2A the example, the sensor 14 is mounted on the central plane 7 of the nacelle and is spaced a distance d1 from the yaw axis 12. If the sensor 14 is moved from its position on the nacelle where it was during the calibration routine, its position is no longer available for measuring the nacelle orientation.

[0059] Figure 3A This problem is illustrated. In this case, the GNSS sensor 14 has been moved a distance d2 from the central plane 7 of the nacelle. The nacelle is pointing north, but the GNSS sensor 14 is now at a position on the circle 16, which would imply that the nacelle 3 has yawed westward.

[0060] This problem makes it desirable to check the position of the GNSS sensor 14 on the nacelle 3 to ensure that it has not been moved since the trajectory data was obtained during the calibration routine.

[0061] Figure 3B illustrates how to solve this problem. The nacelle 3 carries an accelerometer 8 which detects the vibration of the nacelle 3, which occurs most significantly in the longitudinal direction of the nacelle 3 (i.e., in the direction the nacelle faces). For example, if the nacelle 3 faces north, the nacelle 3 will vibrate in the north-south direction.

[0062] The accelerometer 8 can be a biaxial accelerometer, so it can sense the amplitude and direction of the vibration. The accelerometer 8 can be carried by the nacelle, or it can be carried by any other part of the wind turbine that vibrates in unison with the nacelle. The accelerometer 8 can also be built into the GNSS sensor 14, so they are substantially in the same position.

[0063] If the GNSS sensor 14 is located on the central plane 7, the direction of vibration will be radial, in other words, the vibration will be towards and away from the yaw axis 12 at the center of the circle 16, as indicated by the arrow 38, consistent with the radius of the circle. If the sensor 14 is not located on the central plane 7 of the nacelle (because it has moved from the central plane 7, or has been offset by a distance d2 from the central plane 7), the direction of vibration will not be radial. This is indicated by the north-south arrow 34 that does not point to the yaw axis 12. Thus, by sensing whether the direction of vibration is radial, the position of the GNSS sensor 14 can be inferred, and specifically the angle d1d3 can be determined. Thus, the angle d1d3 can be determined by sensing the angle between the direction of vibration and the radial direction.

[0064] If the sensor is in this position during the calibration position measurement, the angle d1d3 obtained via the accelerometer 8 as described above can be stored as part of the trajectory data and used to determine the nacelle orientation. If the sensor is on the central plane 7 during the calibration position measurement and then moves a distance d2, the angular position (angle d1d3) obtained via the accelerometer 8 as described above can be used to apply a correction to the nacelle orientation measurement, as described below.

[0065] Specifically, then the correction angle δ between the vibration direction 34 and the radial direction can be determined, and this correction angle δ is used to apply a correction to the nacelle orientation measurement. The correction process is shown in Figure 3C shown. Figure 3C corresponds to Figure 2B , except that the GNSS sensor 14 has moved a distance d2. Measure the direction 39 of the vibration, measure the correction angle δ between the measurement line 17a and 39; measure the angle θ between the measurement line 17a and 15; then the corrected nacelle orientation measurement value is obtained as θ - δ.

[0066] Now turning to Figure 4, trajectory data indicating more than one trajectory 16, 18 can be obtained. Thus, for a given orientation, the GNSS sensor 14 can measure different positions based on the thrust experienced by the nacelle 3.

[0067] In a first scenario where the nacelle 3 experiences negligible thrust, the GNSS sensor 14 can obtain a first set of trajectory data by measuring a first series of calibrated positions. The first set of trajectory data indicates the first trajectory 16.

[0068] In a second scenario where the nacelle 3 experiences a thrust 20, the GNSS sensor 14 obtains a second set of trajectory data by measuring a second set of calibrated positions. The second set of trajectory data indicates the second trajectory 18. At each position on the trajectory 18, the magnitude of the thrust is the same, but the direction of the thrust is different. The trajectories 16, 18 can be concentric circles centered on the yaw axis 12.

[0069] It can be seen that both the first and second trajectories 16, 18 are circular, with the second trajectory 18 having a larger radius than the first trajectory 16. This is because when the nacelle 3 experiences a thrust 20, the tower 2 carrying the nacelle 3 bends. This causes the nacelle and the GNSS sensor 14 to move. Depending on the direction from which the thrust 20 comes and the direction in which the nacelle 3 is facing, the tower 2 will bend in different directions.

[0070] Then the GNSS sensor 14 can be used to measure the new position; and the orientation of the nacelle can be determined based on the trajectory data of the two circles 16, 18 stored. This can be done in a number of different ways. For example, if the new position falls on one of the circles 16, 18, the trajectory data of that circle can be used to determine the nacelle orientation; and if the new position does not fall on one of the circles 16, 18, the closest circle can be selected. For example, for new positions (x1, y1) and (x2, y2), the closest calibrated position selected in the look-up table can be on the larger (high thrust) circle 18, and for the position (x3, y3), the closest calibrated position selected in the look-up table can be on the smaller (low thrust) circle 16.

[0071] The larger circle 18 can be measured over time by making calibration measurements during times of high wind speed and regularly updating the circles until the circle with the highest radius is measured. The peak thrust of a typical wind turbine can be at a relatively low wind speed (e.g., 9 m / s), so the largest possible circle should be measured fairly quickly.

[0072] In this example, only two circles are measured: circle 16 associated with low (or zero) thrust and circle 18 associated with maximum thrust. Alternatively, one or more additional circles can be measured: for example, a third circle between circles 16, 18 and associated with medium thrust. If a higher number of circles are measured, the new position is more likely to fall on (or close to) one of them, such that the estimate of the nacelle orientation from the look-up table may be more accurate.

[0073] Figure 5 An embodiment is shown having two GNSS sensors 114, 214 carried by the nacelle 3 and spaced apart in the front - rear direction. In this embodiment, trajectory data is obtained, the trajectory data being based on the respective series of calibrated positions measured by each GNSS sensor 114, 214. The trajectory data can include two look - up tables. Each look - up table corresponds to a series of calibrated positions measured by one of the GNSS sensors 114, 214 on the respective trajectories 16a, 16b. The GNSS sensors 114, 214 are located on different trajectories 16a, 16b because they are at different distances from the yaw axis 12.

[0074] After storing the trajectory data, the new positions of each GNSS sensor 114, 214 are measured. These new positions are compared with the stored trajectory data to determine the orientation of the nacelle 3. More specifically, each new position can be input into the look - up table that corresponds to the GNSS sensor 114, 214 from which the new position was obtained.

[0075] Figure 6 An embodiment is shown having two GNSS sensors 314, 414 carried by the nacelle 3 and spaced apart in the left - right direction. In this embodiment, both GNSS sensors 314, 414 measure the same series of calibrated positions because they are located on the same trajectory as each other. This is because the GNSS sensors 314, 414 are equidistant from the yaw axis 12. Thus, the obtained trajectory data typically indicates a trajectory 16 including a single circle on which the GNSS sensors 314, 414 are located.

[0076] As discussed with respect to the previous embodiment, the trajectory data is stored, and after storing the trajectory data, the new positions of each GNSS sensor 314, 414 are measured. The orientation of the nacelle 3 is determined based on the stored trajectory data and the measured new positions.

[0077] The use of multiple GNSS sensors provides the advantage of providing a more accurate and reliable indication of the orientation of the nacelle.

[0078] Now turn to Figure 7, shows a wind turbine having two rotor-nacelle assemblies (RNA). Each RNA includes a respective nacelle 3A, 3B, and the nacelles 3A, 3B carry respective GNSS sensors 514, 614. The RNA rotates about a common yaw axis 112. The two GNSS sensors 514, 614 are equidistant from the yaw axis 112, so when the RNA is yawed, they follow the same trajectory 116.

[0079] As previously described, trajectory data is obtained based on a series of calibrated positions measured by each GNSS sensor 514, 614. In the case where the GNSS sensors 514, 614 are located on the same trajectory 116, a series of calibrated positions can be measured for only one of the GNSS sensors 514, 614, and these positions are not measured for the other sensor to avoid redundancy. The trajectory data is stored.

[0080] As previously discussed, after storing the trajectory data, the new positions of each GNSS sensor 514, 614 are measured. Then the orientation of the nacelle 3 is determined based on the stored trajectory data and the measured new positions.

[0081] Although the present invention has been described above with reference to one or more preferred embodiments, it should be understood that various changes or modifications can be made without departing from the scope of the present invention as defined in the appended claims.

Claims

1. A method for determining the orientation of a nacelle of a wind turbine, wherein the nacelle carries a Global Navigation Satellite System sensor, i.e., a GNSS sensor, the method comprising: Yawing the nacelle between a series of orientations; At each orientation in the series of orientations, measuring a calibration position with the GNSS sensor to generate a series of calibration positions, each calibration position being associated with a corresponding orientation in the series of orientations; Defining trajectory data based on the series of calibration positions and their corresponding orientations; Storing the trajectory data; After storing the trajectory data, measuring a new position with the GNSS sensor; And Determining the orientation of the nacelle based on the stored trajectory data and the new position.

2. The method according to claim 1, wherein Determining the orientation of the nacelle includes: identifying the position in the trajectory data that is closest to the new position; and identifying the orientation of the nacelle corresponding to the identified position.

3. The method according to claim 1 or 2, wherein Determining the orientation of the nacelle by: measuring the thrust experienced by the wind turbine during the measurement at the new position, and determining the orientation of the nacelle based on the measured thrust.

4. The method according to claim 1, wherein, The trajectory data includes multiple sets of trajectory data, each set of trajectory data corresponding to a different level of thrust experienced by the wind turbine.

5. The method according to claim 4, wherein Each set of trajectory data is obtained by yawing the nacelle between a series of orientations, wherein the wind turbine experiences a corresponding thrust among different levels of thrust; And obtaining a set of trajectory data based on a series of calibration positions measured by the GNSS sensor.

6. The method according to claim 4 or 5, wherein Determining the orientation of the nacelle by: selecting one set of trajectory data from the multiple sets of trajectory data based on the new position, and determining the orientation of the nacelle based on the selected set of trajectory data among the multiple sets of trajectory data.

7. The method according to claim 1 or 2, wherein The method further comprises the steps of: determining a correction angle associated with the position of the GNSS sensor on the nacelle, and determining the orientation of the nacelle based on the correction angle.

8. The method according to claim 7, wherein, Determining the correction angle by: using an accelerometer to determine the vibration direction of the wind turbine, and determining the correction angle based on the vibration direction.

9. The method according to claim 1 or 2, wherein The calibration position and the new position are measured by the GNSS sensor relative to a satellite constellation and a terrestrial reference module.

10. The method according to claim 1 or 2, wherein: The nacelle carries multiple Global Navigation Satellite System sensors, i.e., GNSS sensors, Obtaining trajectory data based on a series of calibration positions measured by the GNSS sensors, wherein each calibration position is measured by the GNSS sensors when the nacelle is in a corresponding orientation in the series of orientations; The GNSS sensors each measure a corresponding new position; And Determining the orientation of the nacelle based on the stored trajectory data and the new positions of the GNSS sensors.

11. The method according to claim 1 or 2, wherein, The orientation of the nacelle determined by the method is a geographic orientation.

12. The method according to claim 1 or 2, wherein The trajectory data includes a check of the calibration positions, or a geometric function based on the calibration positions.

13. The method according to claim 1 or 2, wherein, The orientation of the nacelle is determined based on the known positions of the sensors on the nacelle.

14. The method according to claim 13, wherein, The known position of the sensor on the nacelle is obtained by measurement or by design.

15. The method according to claim 14, wherein, The position of the sensor on the nacelle is obtained by: using an accelerometer to determine the vibration direction of the wind turbine and determining the angular position of the sensor on the nacelle based on the vibration direction.

16. A wind turbine, the wind turbine comprising: a tower; a nacelle rotatably mounted on the tower; a global navigation satellite system sensor, i.e., a GNSS sensor, carried by the nacelle; and a control system configured to determine the orientation of the nacelle by the method according to any one of claims 1 to 15.

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