Control of yaw drive of segmented toothed yaw ring for wind turbine

Abstract

A method for yawing a nacelle in a wind turbine, the wind turbine having a yaw assembly including a drive ring and a plurality of drive units configured to apply torque during movement along the drive ring, thereby moving the nacelle relative to the tower. The drive ring is composed of multiple drive ring segments connected at junctions. The method includes defining the position of each junction, defining a reference torque applied by the drive units during movement along the drive ring, defining a reduced torque below the reference torque, determining when a passing drive unit moves past the junction position, and applying a reduced torque by the passing drive unit to improve lifespan.

Description

Technical Field

[0001] This invention relates to a rotary positioning system for wind turbines, and more particularly to a rotary positioning system for a wind turbine yaw system. Background Technology

[0002] WO 2009 / 068036 A2 describes a wind turbine based on the current state of the technology. For yaw control, it includes a yaw mechanism with one or more yaw motors (i.e., rotary positioning drives), and a yaw bearing forming a rotatable connection between the wind turbine tower and the nacelle. The yaw drive engages with a drive ring, i.e., a ring with internal or external teeth that is fixedly connected to the top of the tower or the nacelle via a pinion. Other wind turbine yaw systems are known from EP 1571 334 A1 or WO 2008 / 053017 A3.

[0003] As wind turbines become larger, drive rings become larger, and the torque required for nacelle rotation also increases. Summary of the Invention

[0004] One object of the present invention is to allow the drive ring to be manufactured in sections, thereby allowing for easier manufacturing, replacement and transportation without affecting the expected lifespan of the yaw assembly.

[0005] Another objective of this invention is to improve the operational safety of wind turbines.

[0006] For these and other purposes, the invention is defined in the independent claims, and further aspects of the invention are set forth in the dependent claims, the drawings and the following description.

[0007] According to a first aspect, the present invention provides a method for yawing a nacelle in a wind turbine, the wind turbine having a yaw assembly including a drive ring and a plurality of drive devices configured to engage with the drive ring to move the nacelle relative to the tower, the drive ring being composed of a plurality of drive ring segments connected at a junction, the method comprising:

[0008] Define the position of the intersection point relative to the drive unit.

[0009] The reference torque applied by the drive unit when moving the nacelle relative to the tower is limited.

[0010] The reduced torque is limited to a value below the reference torque.

[0011] Reduced torque is applied by the crossing drive located at the intersection.

[0012] This process may include determining a position or time step in which the crossing drive unit passes through the junction and reduces torque during that time step. In the following text, N_crossing is the number of drive units crossing the junction.

[0013] When the drive ring is composed of individual segments assembled at the junction, there is a risk of irregularities at the junction, such as those caused by misalignment between adjacent segments or by incompletely continuous tooth patterns at the junction. Wear on the drive ring or drive unit can be reduced and expected lifespan increased, even if irregularities are introduced by the segmentation of the drive ring, as the torque across the drive unit is reduced.

[0014] The drive ring can be fixed to a tower or nacelle, and then the drive unit is attached to another one in the tower or nacelle. Regardless of the position of the drive ring on the tower or nacelle, we refer to the traversing drive unit herein to define the drive unit that traverses the junction between two drive ring segments. In one embodiment, both the drive unit and the traversing drive unit are fixedly connected to the tower, while in another embodiment, they are movable with the nacelle.

[0015] The yaw component can be controlled by a controller that operates according to known control principles (such as torque control or speed control).

[0016] The reduced torque is applied by the traversing drive mechanism. The reduced torque can be applied, for example, within a reduced region extending beyond the junction, such as ±0.1-10 degrees relative to the junction, ±0.5-10 degrees relative to the junction, or ±0.5-1.0 degrees relative to the junction. In one embodiment, the reduced region is a variable control setting in the controller of the yaw component.

[0017] The reduced torque can be applied by the drive unit of the crossing to cause the nacelle to move relative to the tower, i.e., when the drive unit of the crossing actively drives the nacelle to move relative to the tower, or the reduced torque can be applied by the drive unit of the crossing to resist the movement of the nacelle relative to the tower, i.e., when the drive unit of the crossing is used as a brake to brake the movement of the nacelle relative to the tower.

[0018] Braking can be achieved by a mechanical brake acting on the drive pinion or rotor shaft of the drive unit, or electrically by reversing the electric field in a selected drive unit. For a passing drive unit, the braking effect is reduced, resulting in a decrease in torque.

[0019] In the following text, N_drives refers to the total number of drive units, and each drive unit may have a drive unit number N. Similarly, x refers to the total number of junctions, and each junction may have a junction number X. The yaw assembly may be configured with n drive units, the number of which differs from the number of junctions x. Specifically, when at least one of x and N is a prime number and x and N are distinct numbers, there will never be two drive units simultaneously located at a junction, and at least N_drives minus one drive unit will be able to operate to apply a torque higher than the reference torque.

[0020] The reduced torque can be limited to a single torque for each junction, such that for each junction, there is a single limited reduced torque.

[0021] The reduced torque can be defined based on the severity of the irregularity caused by the intersection between the two segments, for example, it can be defined as a percentage of the reference torque.

[0022] The reduced torque, for example, as a percentage of the reference torque, can be dynamically updated based on the response from the drive unit moving at the intersection point.

[0023] For one or more drives that are not crossing, the torque can be increased relative to the reference torque. This can provide sufficient torque for nacelle yaw (even in high wind conditions) and offset torque losses from the crossing drives.

[0024] According to a second aspect of the invention, a wind turbine with a yaw assembly is provided, the yaw assembly including a drive ring and a plurality of drive devices configured to apply torque during movement along the drive ring, thereby moving the nacelle relative to the tower. The drive ring is composed of a plurality of drive ring segments connected at an intersection point. The wind turbine includes a yaw controller configured to:

[0025] Define the position of the intersection point relative to the drive unit.

[0026] The reference torque is defined as the torque applied by the drive unit when moving along the drive ring.

[0027] Limit the reduced torque below the reference torque, and

[0028] The reduced torque is applied by the driving unit as it passes the junction.

[0029] Because the junction points are defined during the design of the wind turbine, the controller can be programmed to reduce torque at each junction, thereby increasing lifespan, even for large wind turbines with segmented drive rings. An advantage at the design stage is that the drive ring size can be set based on the strength of the ring itself, without needing adjustments for the reduced strength at the junction points.

[0030] The wind turbine may include position sensors configured to determine the position of each drive unit relative to each junction point, specifically, position sensors arranged at each junction point.

[0031] Any of the features mentioned in relation to the method in the first aspect of the invention may also be applied to wind turbines according to the second aspect of the invention. Attached Figure Description

[0032] In the following, embodiments of the present disclosure will be described in further detail with reference to the accompanying drawings, wherein:

[0033] Figure 1 A wind turbine is shown;

[0034] Figure 2 The yaw assembly is shown;

[0035] Figure 3 The control system used to control yaw is shown schematically;

[0036] Figure 4 An advanced yaw controller is shown;

[0037] Figures 5 to 8 The control sequence of the two drive units as they pass through the junction is shown; and

[0038] Figure 9 The results ratio for a single drive unit is shown. Detailed Implementation

[0039] The detailed description and specific examples are given by way of illustration only when indicating embodiments, since various changes and modifications within the spirit and scope of this disclosure will be apparent to those skilled in the art based on the detailed description.

[0040] Figure 1 A wind turbine 102 with a nacelle 104 and a hub 106 is shown, the hub 106 having blades 110 that rotate relative to the nacelle 104 via a main shaft. The wind turbine includes a yaw assembly that allows the nacelle to rotate about the main axis 112 of the wind turbine tower 108, indicated by arrow 114. This wind turbine is a horizontal axis wind turbine, but the invention is equally applicable to multi-rotor wind turbines or other types of wind turbines.

[0041] Figure 2 The yaw assembly 116 and yaw controller 202 are shown. The yaw assembly includes a drive ring 206 with a toothed structure and a plurality of drive units 208 configured to apply torque during movement along the drive ring, thereby moving the nacelle relative to the tower.

[0042] The drive ring is attached to one of the nacelle and the tower, and the drive unit is attached to the other of the nacelle and the tower. In the illustration, the drive ring has external teeth, but it can alternatively have other tooth structures, such as internal teeth.

[0043] Each drive unit consists of a pinion and a motor, in this case an electric yaw motor, but alternatively a hydraulic motor configured to drive the pinion meshing with a drive ring.

[0044] Yaw controllers typically operate using known control methods and are capable of individually controlling each drive unit. Controlled parameters can be, for example, torque, speed, or position, or combinations thereof. The controller can therefore be configured to individually reduce the torque applied by each drive unit. The torque can be reduced to a percentage of a reference torque or reduced to zero, for example, by shutting off the passing drive unit. The drive unit can even provide negative torque, i.e., in the opposite direction of drive.

[0045] In one implementation, the yaw motor is on / off controlled, which in this context means that the drive motor is shut off as its position approaches the junction, for example by a position sensor or by a controller based on its perception of speed and acceleration. Angular velocity and acceleration can be determined, for example, by using encoders mounted on each motor or on the interface between the tower and the nacelle (e.g., on the drive ring). If the motor is shut off, the resulting torque is typically negative because movement of the nacelle relative to the tower will have to move the shut-off drive.

[0046] In another embodiment, the yaw motors receive rotation angle input via a communication path shown by dashed line 210, and they have angle sensors 212. The rotation angle input can be, for example, a specific desired angle and torque, or it can be the duration of operation and torque. Once this input is received, the drive unit determines, via internal control, how to operate to obtain the desired torque and angle or the duration of operation.

[0047] Angle sensor 212 is arranged to sense the angle output of drive unit 208. For example, in order to monitor the complete transmission chain of the yaw system in one step, the yaw system or yaw monitoring system in the illustrated embodiment further includes nacelle angle output sensor 214, which is positioned and adapted to determine the rotation angle of the wind turbine nacelle relative to the tower.

[0048] The drive ring is composed of multiple drive ring segments connected at junction 217. This facilitates easier transportation, especially for very large wind turbines, and makes it easier and cheaper to manufacture wind turbines.

[0049] The drive ring shown has teeth on the outside and interacts with a pinion of the drive unit (e.g., in the shape of a gear on each drive unit). The interaction between the drive unit and the drive ring can be achieved in other different ways, such as based on friction or through a chain and sprocket.

[0050] In one embodiment, the yaw controller 202 receives position information and controls the yaw motors to start and stop. In another embodiment, the yaw controller 202 is arranged to receive rotation angle input 210, which may be each of a plurality of yaw motors 208, angle output of each of the plurality of yaw motors 208 sensed by angle sensor 212, and rotation angle of the wind turbine nacelle relative to the wind turbine tower. The yaw controller 202 is adapted to define the position of each junction, define a reference torque applied by the drive unit as it moves along the drive ring, define a reduced torque below the reference torque, determine the time step in which the traversing drive unit moves past the position of the junction, and send a signal to the drive unit via communication path 210 to apply a reduced torque by the traversing drive unit within the determined time step.

[0051] exist Figure 2 In the middle, the drive unit 208' is the traversing drive unit because it is passing through the intersection point 217 between the two drive ring segments.

[0052] Drive ring segments are connected, for example, by assembly components, such as bolts, or by welding. Regardless of the assembly process, errors and irregularities can lead to increased wear on the drive unit.

[0053] Figure 3 This is an angle input-output diagram of the yaw system's transmission chain. The diagram shows input 302, which contains the angle and desired torque, or the duration of operation and desired torque. This input is received by multiple drive units 208. Input 302 is... Figure 2 The yaw controller 202 shown generates this. Where possible, input 302 is the same for each drive unit, except for the drive unit for which a lower torque is specified.

[0054] The measured angle output of each drive unit 208 is measured or sensed at 304 by measuring gear angle output 306.

[0055] The drive units shown can operate in drive mode and braking mode. In drive mode, they actively rotate the nacelle, and in braking mode, they brake or prevent the nacelle from rotating.

[0056] By equipping the yaw assembly with n drive units, the number of drive units differs from the number x of intersection points between drive ring segments of the same size. Specifically, by setting this number so that N_drives is a prime number and x differs from N, there is no risk that two drive units will simultaneously become crossing drive units. Figure 2 In this case, the number of driving devices n is 4, and the number of segments x is 5, which is a prime number.

[0057] Figure 4 An advanced version of a yaw controller 202, including a computer system 401, is shown. This computer system is configured to individually limit the reduced torque at each junction. The computer system may, for example, have information related to irregularities, such as the magnitude of the offset between adjacent segments, and the expected wear caused by each junction. The computer system can be configured to calculate the desired reduction in torque, taking into account the irregularities. The reduced torque may, for example, be limited as a percentage of a reference torque, and this percentage may be limited based on the severity of the irregularities caused by the junction between two segments. In a first operating mode, the computer may have a fixed setting for the reduced torque, while in a second operating mode, it may dynamically update the setting for the reduced torque, for example, based on the response from the drive mechanism moving past the junction position.

[0058] The yaw controller can also calculate the increased torque to boost the output of the drives that are not crossing, thereby compensating for the reduction in torque applied by the crossing drives. In one embodiment, the difference between the reference torque and the reduced torque is split equally among the non-crossing drives, and this amount is added to the torque of the non-crossing drives.

[0059] The yaw controller can calculate the total cumulative torque at each junction or the number of times the junction has been passed by the drive unit. Based on the total torque or the number of passes, it can determine the level of reduction, i.e., the reduction in torque.

[0060] Figures 5 to 8 The control sequence of the drive unit as it passes through the junction is shown. Figure 5 In this diagram, drive units N_1, N_2, and N_3 are monitored using ratio diagrams 51(N_1), 52(N_2), and 53(N_3). The intersection point is marked as 217. Figure 5In the middle, the intersection points 217' and 217" are located on opposite sides of the monitored drive units N_1, N_2 and N_3, and the monitored drive units N_1, N_2 and N_3 are not considered as traversing drive units.

[0061] exist Figure 6 The figure shows that the torque of N_1 is reduced, i.e., the torque curve is at the position indicated by the vertical line 61.

[0062] exist Figure 7 The figure shows that the torque of none of N_1, N_2 and N_3 is reduced, that is, the torque curve is at the position indicated by the vertical line 71.

[0063] exist Figure 8 The figure shows that the torque of N_2 is reduced, i.e., the torque curve is at the position indicated by the vertical line 81.

[0064] The strategy to reduce torque can be explained as follows:

[0065] By setting Reduce = 1 for those drive units, all drive units located within a certain distance ±Δθ from the junction point are identified, N_crossing. When one or more drive units enter or leave the junction point at a distance of ±Δθ, the yaw angle is saved as θ_trig. Similarly, all current output ratios for each drive unit are saved as ratio_ol = ratio.

[0066] Determine the coefficient δ_increase to be added to drive units not near the segment to compensate for the reduced torque on other drive units. The total number of drive units is N_drives, and δ_reduce is the reduction coefficient. This should ensure that the combined motor torque always equals the total torque reference value, i.e.: N_crossingδ_reduce + (N_drives - N_reduce)δ_increase = N_drives

[0067] δ_increase=(N_drives-N_crossingδ_reduce) / (N_drives-N_crossing)

[0068] Compared to active yaw, torque from a drive unit can be reduced when passing through an intersection by using position feedback.

[0069] Each time they are changed, the decrease coefficient δ_reduce and the increase coefficient δ_increase are stored as reference values.

[0070] Figure 9The result ratio for a single drive unit is shown. When δreduce = 0.8, the result ratio for a single drive unit can be seen as follows.

[0071] As can be seen, due to the sigmoid function, the output ratio 91 is merely a smoothed version of the reference ratio 92. The function is shifted by δ_θ, starting from zero very close to the variation in the input ratio. If a steeper or less steep slope is desired, it can be easily obtained by changing α, but the important region is where the ratio reaches 0.8 due to the reduction in the segmentation. This can be shifted so that the segmentation splits directly in the middle, which would require Δθ to be larger before the split than after.

Claims

1. A method for yawing a nacelle (104) in a wind turbine (102) relative to a tower (108), the wind turbine having a yaw assembly including a drive ring (206) and a plurality of drive devices (208) configured to engage with the drive ring and apply torque to move or stop the nacelle (104) relative to the tower (108), the drive ring (206) being composed of a plurality of drive ring segments connected at a junction (217), the method comprising: The position of the intersection point (217) relative to the driving device (208) is defined. The reference torque expected to be applied by the drive device (208) is defined. The reduced torque is limited to a value lower than the reference torque, and When the traversing drive unit passes the junction, the reduced torque is applied by the traversing drive unit.

2. The method of claim 1, wherein, The reduced torque is the driving torque applied by the drive unit of the crossing to cause the nacelle to move relative to the tower.

3. The method of claim 1, wherein, The reduced torque is a braking torque applied by the drive unit of the crossing to resist movement of the nacelle relative to the tower.

4. The method of any one of claims 1-3, wherein, The yaw assembly is designed to prevent more than one drive unit from passing through the junction at the same time.

5. The method of claim 4, wherein, The number of intersection points x and the number of driving devices N_ drives At least one of them is chosen to be a prime number, and x is... N_drives different.

6. The method of any one of claims 1-3, wherein, The reduced torque is limited to a single torque for each intersection point.

7. The method according to any one of claims 1-3, wherein, The reduction in torque is defined as a percentage of the reference torque.

8. The method of any one of claims 1-3, wherein, The reduction in torque is based on the severity of the irregularity caused by the intersection point between the two segments.

9. The method of any one of claims 1-3, wherein, For one or more drive units that are not crossing, the torque increases relative to the reference torque, while for the drive unit that is crossing, the torque decreases.

10. The method of any one of claims 1-3, wherein, The total torque is defined as the sum of the torques applied by all drive units, and its variation over time is continuously determined.

11. The method of claim 10, wherein, Determine the total number of times the intersection point has been passed by the driving device.

12. The method of claim 11, wherein, The reduced torque is determined based on the total torque or the total number of times the intersection has been passed by the drive unit.

13. The method of any one of claims 1-3, wherein, The method includes preventing the nacelle from stopping relative to the tower at an interference position, where the drive unit is located at the intersection point.

14. The method of claim 13, wherein, By controlling the braking sequence to avoid stopping at the interference location, the nacelle is prevented from stopping relative to the tower at the interference location.

15. The method of claim 13, wherein, The nacelle is prevented from stopping relative to the tower at the interference position by actively moving the nacelle away from the interference position using the drive device.

16. The method of any one of claims 1-3, wherein, The method includes defining a reduced region extending beyond the intersection and reducing the torque of the drive device for the crossing within the reduced region.

17. The method of claim 16, wherein, The reduction area is defined as a variable setting in the controller of the yaw component.

18. The method according to any one of claims 1-3, wherein, The drive unit is controlled by shutting down the drive unit used for crossing.

19. A wind turbine (102) including a tower (108) and a nacelle (104), and having a yaw assembly (116) including a drive ring (206) and a plurality of drive devices (208) configured to apply torque to move or stop the nacelle (104) relative to the tower (108), the drive ring (206) being composed of a plurality of drive ring segments connected at an intersection (217), the wind turbine including a yaw controller (202) configured to: The position of the intersection point (217) relative to the driving device (208) is defined. The reference torque applied by the drive device (208) is defined. The reduced torque is limited to a value lower than the reference torque, and When the traversing drive unit passes through the intersection, the reduced torque is applied by the traversing drive unit.

20. A wind turbine according to claim 19, wherein, The wind turbine includes a position sensor configured to determine the position of each drive unit relative to each intersection point.

21. A wind turbine according to claim 19 or 20, wherein, The wind turbine includes position sensors arranged at each intersection point.

22. A wind turbine according to claim 19 or 20, wherein, The yaw controller is configured to control each drive unit individually.

23. A wind turbine according to claim 19 or 20, wherein, The yaw controller is configured to turn each drive unit on or off individually.

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