WO2015135552A1

WO2015135552A1 - Lidar alignment tool for aligning a lidar system with a rotation axis of a rotor of a wind turbine

Info

Publication number: WO2015135552A1
Application number: PCT/DK2015/050053
Authority: WO
Inventors: Thomas Nicholas Markus DYHR
Original assignee: Windar Photonics A/S
Priority date: 2014-03-14
Filing date: 2015-03-16
Publication date: 2015-09-17

Abstract

This invention relates to a method of aligning a LIDAR system with a rotation axis of a rotor of a wind turbine using a LIDAR alignment tool comprising at least a wind turbine alignment interface configured for aligning the LIDAR alignment tool with a rotation axis of a wind turbine, at least a LIDAR alignment interface configured for aligning the LIDAR alignment tool with a LIDAR system so that a laser beam pointing direction of a LIDAR system can be aligned with the LIDAR alignment tool, and the LIDAR alignment tool comprises a gyroscope configured for obtaining a substantially fixed spin axis, which LIDAR alignment tool is configured to record a spin axis direction of the fixed spin axis constituting the one to-one reference between the spin axis direction and each of the wind turbine alignment interface and the LIDAR alignment interface.

Description

LIDAR Alignment Tool for Aligning a LIDAR System with a Rotation Axis of a Rotor of a Wind Turbine

Field of invention

This invention relates to a method of aligning a LIDAR system with a rotation axis of a rotor of a wind turbine using a LIDAR alignment tool comprising at least a wind turbine alignment interface configured for aligning the LIDAR alignment tool with a rotation axis of a wind turbine, at least a LIDAR alignment interface configured for aligning the LIDAR alignment tool with a LIDAR system so that a laser beam pointing direction of a LIDAR system can be aligned with the LIDAR alignment tool, and the LIDAR alignment tool comprises a gyroscope configured for obtaining a substantially fixed spin axis and thus an accurate direction of the wind turbine axis, which LIDAR alignment tool is configured to record a spin axis direction of the fixed spin axis constituting the one to- one reference between the spin axis direction and each of the least wind turbine alignment interface and the least LIDAR alignment interface. Background of the invention

This invention relates to a method of aligning a laser beam pointing direction of a LIDAR system with a rotation axis of a rotor of a wind turbine using a LIDAR alignment tool. It is known to use a laser alignment system for this purpose. The accuracy of the alignment using a laser alignment system depends on the setup around the laser. Laser alignment systems often work by pointing a laser from one device towards a positioning sensor in another device, whereas both devices have to be placed very accurate on the LIDAR system and somewhere on the wind turbine in order to obtain an accurate alignment. This is difficult to do as brackets and the like on the wind turbine are not mounted very accurately. The process of alignment is therefore work intensive and the angle which the laser alignment system is mounted in becomes rather coincidental. Furthermore, a laser alignment system used in the field wind will be influenced by the wind turbine movements as well as temperature. The LIDAR system must prospectively be mounted on all the existing as well as new wind turbines being developed all over the world. The alignment tool must therefore preferably be able to align a LIDAR system accurately on many different wind turbines. The laser alignment technology used today as well as other mechanical aligning technologies does not apply with an accurate alignment of the LIDAR system from one wind turbine to the next and requires calibration between each use.

The efficiency, with which a wind turbine can extract power from the wind, depends on various factors such as for example the wind speed and wind direction. For achieving wind control, the wind turbines are provided with a LIDAR system. The LIDAR system is arranged to scan the area in front of the wind turbine in order to generate a measurement of the wind speed and wind direction in relation to the direction of the rotational axis of the rotor. It is known that if the wind direction is offset to the rotational axis direction of the rotor by e.g. 8 degrees to either one of the sides this roughly corresponds to a 2% power loss. Thus, the LIDAR system must be aligned to the rotation axis of the rotor with a high accuracy in order to obtain the optimal rotation axis direction compared to the actual wind condition.

An effect of the present invention is to obtain a more accurate alignment of the LIDAR system than obtained by any other alignment system being used today, as well as a LIDAR alignment tool that is less work intensive and true to the alignment of the LIDAR system regardless of wind turbine type. Summary of invention

In a first aspect of the present invention is provided a LIDAR alignment tool, comprising: one or more wind turbine alignment interface(s), the alignment interface(s) defining a LIDAR alignment tool axis, wherein at least one of said interfaces is configured for being mechanically aligned with a rotating member of a wind turbine; a gyroscope mechanically fixed to the LIDAR alignment tool and configured for providing a direction, such that the direction is referenced with respect to a direction of the alignment tool axis; and one or more LIDAR alignment interfaces(s), wherein at least one of said LIDAR alignment interfaces is configured for being mechanically aligned with a LIDAR system .

In a second aspect of the present invention is provided a kit of a LIDAR alignment tool as described in the first aspect and a LIDAR system configured for being mechanically aligned with the LIDAR alignment tool by having a corresponding LIDAR alignment interface. In a third aspect of the present invention is provided a method for aligning a LIDAR system to a rotation axis of a wind turbine, comprising the steps of: providing a LIDAR alignment tool configured for providing a direction; placing the LIDAR alignment tool on a rotating member of the wind turbine, the rotating member defining the rotation axis; obtaining and recording the direction as a reference direction from the LIDAR alignment tool such that the reference direction is referenced with respect to the direction of the rotation axis; moving the LIDAR alignment tool from the rotation axis and placing it onto the LIDAR system, thereby obtaining an adjustment direction; and adjusting the LIDAR system according to the adjustment direction and relative to the reference direction, thereby aligning the LIDAR system to the rotation axis of the wind turbine.

In fourth aspect of the present invention, there is provided operation of a wind turbine with a rotation axis aligned with a LIDAR system, which alignment of rotation axis and LIDAR system is performed by a LIDAR alignment tool as described in the first aspect of the present invention and/or by a method of aligning as described in the third aspect of the present invention.

An effect of the invention may be achieved by a method of aligning a LIDAR system (with a rotation axis of a rotor of a wind turbine, using a one-to-one wind turbine alignment reference between the wind turbine and the rotation axis and a LIDAR alignment tool comprising: at least a wind turbine alignment interface configured for aligning the LIDAR alignment tool with a rotation axis of a wind turbine; at least a LIDAR alignment interface configured for aligning the LIDAR alignment tool with a LIDAR system so that a laser beam pointing direction of a LIDAR system can be aligned with the LIDAR alignment tool; the LIDAR alignment tool comprises a gyroscope configured for obtaining a substantially fixed spin axis , which LIDAR alignment tool is configured to record a spin axis direction of the fixed spin axis constituting the one to-one reference between the spin axis direction and each of the least wind turbine alignment interface and the least LIDAR alignment interface; the method comprising: aligning the LIDAR alignment tool with a rotation axis, using the wind turbine alignment interfaces to align the LIDAR alignment tool with a rotation axis of a rotor; recording the spin axis direction of the gyroscope within the LIDAR alignment tool so that a rotation axis direction of a rotor is recorded by the LIDAR alignment tool; aligning the LIDAR alignment tool with a LIDAR system by using the LIDAR alignment interface; adjusting a laser beam pointing direction of a LIDAR system in accordance with the recorded rotation axis direction of a rotor recorded by the LIDAR alignment tool; thereby aligning a LIDAR system to a rotation axis of a rotor. Thereby is provided a method of aligning a LIDAR system with a rotation axis of the rotor of a wind turbine. The method may require less work than otherwise. The method may be more accurate, and the accuracy may even be in the order or less than ±0.5 degrees. From one perspective, the method makes it easier or more convenient to work inside the nacelle of a wind turbine to get information about the direction of the rotation of the rotor blades and the transfer such information to the outside of the nacelle to a LIDAR arrangement. At the same time the method may even be more accurate than by using existing methods and/or equipment.

By one-to-one alignment reference is meant a reference which constitutes a known or obvious relation between one means and another means. Such one-to-one alignment reference may be the main shaft of a wind turbine. Another reference may be a break disc of the rotor, which break disc is perpendicular to rotational axis. Another reference may be a mechanical interface or reference established during manufacturing as a reference.

By substantially is meant sufficiently or as accurate as possible. This invention discloses a method or system where the direction of the wind turbine center line - often found to be equal to the direction of the main shaft in the nacelle - is projected to the center line of the LIDAR system and thereby assuring that the LIDAR system is accurately parallel to the direction of the wind turbine center line in the nacelle.

The LIDAR alignment tool records the exact position of the nacelle center line and transports this center line to the LIDAR system casing whereby the exact direction is transferred to the LIDAR system.

An accurate alignment is by one means obtained by having a LIDAR alignment tool comprising at least one alignment interface configured for a substantial accurate alignment with the rotational axis of the rotor of the wind turbine. This is obtained by using a known one-to-one wind turbine alignment reference between the wind turbine and the rotation axis of the rotor. The one-to-one wind turbine alignment reference may preferably be directionally well defined by operation such as a wind turbine main shaft or the like known by the skilled person to be substantially parallel to the rotation axis of the rotor or a rotor brake disc or the like known to be substantially perpendicular to the rotation axis of the rotor.

An accurate alignment is by another means obtained by using a LIDAR alignment tool only comprising one device which is aligned with the rotation axis of the rotor once, whereafter it is moved and aligned with the LIDAR system. This gives the skilled person the freedom to choose and use the best suitable one-to-one alignment reference on or in the wind turbine and on the LIDAR system for alignment with the LIDAR alignment tool. Thereby, it is avoided to constrain the use of the LIDAR alignment tool to be used on certain means, surfaces or the like due to a LIDAR alignment tool consisting of two devices which need some kind of visible or physical contact in between them. The LIDAR alignment tool can thereby be used on all types of wind turbines and retain an accuracy of ± 0.5 degrees as long as there on the wind turbine and/or the LIDAR system can be identified a one-to-one alignment reference. Another beneficial effect of the alignment process comprising one device which is aligned with the rotation axis of the rotor once where after it is moved and aligned with the LIDAR system is that it is easy to bring back the LIDAR alignment tool later on at any occasion and control the alignment of the LIDAR system. Yet another beneficial effect of using a LIDAR alignment tool only comprising one device, is that the entire process of aligning the LIDAR system with the rotation axis of the rotor only takes a few minutes compared to the more work intensive laser alignment system. The reason a LIDAR alignment tool only comprising one device works is due to the gyroscope within the LIDAR alignment tool. Using a gyroscope within the LIDAR alignment tool to record a one-to-one wind turbine alignment reference between the spin axis direction of the gyroscope and one or more alignment interfaces of the LIDAR alignment tool is preferable because of the high accuracy and stability of the

gyroscopes available today. Furthermore, the gyroscope is not sensitive to the wind as such during the alignment but is equally sensible to the movement of the wind turbine. However, it is still possible to reach a centre based on the pendulum movement of the nacelle in rather high winds and still reach an accuracy below ±1 .00 degrees, and obtainable below ±0.50 degrees. A centre may at least be determined visually or by a predetermined definition.

One applicable gyroscope may be a so-called MEMS gyroscope with an extremely low drift less than 0.5 degrees /hour, but not limited hereto and a person skilled in the art will be able to search the market for gyroscopes of even less than 0.5degrees/month. Furthermore the gyroscope including the MEMS type will in combination with low drift be operable at temperature intervals ranging from -40 C to +85 C.

Finally the gyroscope including the MEMS type will preferably have a low energy consumption and maybe powered by batteries, say for up to 3 hours or sufficient for performing an alignment.

In an embodiment the method further comprises the step of resetting the LIDAR alignment tool while the LIDAR alignment tool is aligned with a rotation axis.

When resetting the LIDAR alignment tool, the spin axis direction of the gyroscope obtains a substantially parallel direction to the rotation axis direction of the rotor. The effect of this, is to obtain the best possible precision of the gyroscope in use and thereby an accurate alignment of the LIDAR system.

In an embodiment the method further comprises using the same alignment interface as the LIDAR alignment interface and the wind turbine alignment interface.

Thus is the use of the LIDAR alignment tool simplified, such that the two alignment interfaces cannot be confused with each other and thereby cause an inaccurate alignment of the LIDAR system. Thus is also provided the opportunity for a LIDAR alignment tool with a compact design, which is easier handled when working in heights. In one embodiment the alignment interfaces may be combined in one alignment interface. Combining the two alignment interfaces in one alignment interface supports the opportunity of specialising each part of the alignment interface so that the one part of the alignment interface specialised to be the LIDAR alignment interface and the second part of the alignment interface specialised to be the wind turbine alignment interface may align with different tolerances. Thus, the combining of two alignment interfaces configured to be used on different wind turbines and LIDAR systems, facilitates a more accurate alignment where corresponding alignment interfaces are available and simplifying the use.

In an embodiment the method further comprises, using a LIDAR alignment tool configured to display the recorded rotation axis direction of a rotor in real time.

The displayed rotation axis direction is a one-to-one alignment reference between the rotation axis direction and the wind turbine alignment interface as well as the rotation axis direction and the LIDAR alignment interface. While the LIDAR alignment tool is aligned with the rotation axis of the rotor, the displayed rotation axis direction is used to make it visible whether the rotation axis direction of the rotor has been recorded by the LIDAR alignment tool or not. Thereafter, when the LIDAR alignment tool has been moved from the wind turbine alignment interface, the recorded and displayed rotation axis direction is used to visualise the deviation from the aligned direction of the wind turbine alignment interface and the actual direction of the wind turbine alignment interface and/or the LIDAR alignment interface. Thus, it is made visible whether two means or surfaces aligned with the wind turbine alignment interface or the LIDAR alignment interface have the same direction.

The LIDAR alignment tool might both display a horizontal and/or a vertical recorded rotation axis direction of the rotor. The horizontal recorded rotation axis direction is preferred.

In one embodiment the gyroscope may be configured to align in one dimension. In other embodiments, the gyroscope may be configured to align in two or three dimension. Furthermore each dimension may be supplemented by accelerometers to improve reliability or provide further orientation information or information about drift or impacts.

In an embodiment the one dimension is the dimension aligning the horizontal position. In an embodiment the method further comprises, using means configured to automatically align a LIDAR system to the recorded rotation axis direction of a rotor within a tolerance of ±1 .0 degrees and preferably within a tolerance of ±0.5 degrees. Using an alignment tool based on a gyroscope that has a drift of less than 0.5 degrees/h, such tolerances may be achieved. Typically, an alignment process lasts roughly 5 minutes, which gives a fair margin to achieve the stated tolerances. A person skilled in the art will realize that using a gyroscope with an even less degree of drift will even further improve the alignment tolerance. A person skilled in the art will appreciate that the tolerance of alignment is a function of the drift. Although a MEMS type gyroscope is readily available off the shelf of certain drift, it is clear that state of the art gyroscopes may have a lower drift and thus in principle make it possible to obtain lower tolerances. However, the person skilled in the art will also appreciate that ease of use, and value consideration will define a practical lower limit where there is a trade-off of effect. Automatic alignment is often more accurate, less time consuming and more user- friendly than manual alignment. The automatic alignment is facilitated by the alignment interfaces on the LIDAR alignment tool as well as the fact that the LIDAR alignment tool is only one device configured for recording a one-to-one alignment reference between the spin axis direction of the gyroscope and respectively the wind turbine alignment interface as well as the LIDAR alignment interface, all being a part of the LIDAR alignment tool.

The automatic alignment may furthermore be obtained through a wired or wireless connection between the LIDAR alignment tool and the LIDAR system, while the two are aligned using the recorded rotation axis direction to align the LIDAR system.

In an embodiment, servo motors may be used to perform the adjustments. Such auto alignment may be advantageous when aligning multiple systems to a common references or when the alignment has to be performed during special conditions. In either case an alignment may be prepared and then performed as required.

In an embodiment the method further comprises, using the LIDAR alignment interface and a corresponding LIDAR alignment interface to align the LIDAR alignment tool so that the recorded rotation axis direction is parallel with a laser beam pointing direction.

Aligning a LIDAR system configured with an alignment interface corresponding to the LIDAR alignment interface of the LIDAR alignment tool is not necessary but preferred in order to obtain the wanted accuracy of ±0.5 degrees and thereby obtaining an accurate alignment of the LIDAR system. This is so that the LIDAR system can influence the rotor inclusive the rotor blades on the wind turbine to adapt to the actual wind condition as accurate as possible avoiding unnecessary power loss.

In an embodiment of aligning a LIDAR system using a LIDAR alignment tool as disclosed which communicates with an external position reference system. An effect of the invention may further be achieved by a LIDAR alignment tool comprising: at least a wind turbine alignment interface configured for aligning the LIDAR alignment tool with a rotation axis of a wind turbine; at least a LIDAR alignment interface configured for aligning the LIDAR alignment tool with a LIDAR system so that a laser beam pointing direction of a LIDAR system can be aligned with the LIDAR alignment tool, where the LIDAR alignment tool comprises a gyroscope configured for obtaining a substantially fixed spin axis, which LIDAR alignment tool is configured to record a spin axis direction of the fixed spin axis constituting a one-to-one alignment reference between the spin axis direction and each of the least wind turbine alignment interface and the least LIDAR alignment interface.

In an embodiment the LIDAR alignment interface and the wind turbine alignment interface are the same alignment interface.

In an embodiment the LIDAR alignment interface is a triangular recess.

A triangular recess may be advantageous since it facilitates easy alignment with substantially plate- or disc shaped means as well as substantially round surfaces. In an embodiment the LIDAR alignment tool is configured with means for displaying the recorded rotation axis direction of a rotor in real time.

An objective of the invention is achieved by a kit of a LIDAR alignment tool and a LIDAR system configured for being aligned with a rotation axis of a rotor of a wind turbine using the LIDAR alignment tool by having a corresponding LIDAR alignment interface.

The person skilled in the art will appreciate aligning a LIDAR system that is configured for being aligned with said LIDAR alignment tool. An objective of the invention is achieved by the operation of a wind turbine with a rotation axis aligned with a LIDAR system, which alignment of rotation axis and LIDAR system is performed by a LIDAR alignment tool or by the method of aligning a LIDAR system as described above. In an embodiment of operating a wind turbine the rotation axis of the wind turbine is aligned with the LIDAR system to within a tolerance of ±0.5 degrees. With such tolerance of alignment, the operation of the wind turbine becomes more efficient and enables the wind turbine and or the operator of the wind turbine to harvest energy more efficiently and thereby minimising the unnecessary power loss related to inaccurate alignment. A further effect is that a more precise alignment will result in less stress and tear on the wind turbine during operation.

Brief Description of Drawings

Embodiments of the invention will be described in the figures, whereon:

Fig. 1 shows a wind turbine provided with a LIDAR system aligned with a rotation axis of a rotor of the wind turbine;

Fig. 2 shows an embodiment of a LIDAR alignment tool comprising a gyroscope;

Fig. 3A-D show different possible shapes of alignment interfaces of a LIDAR alignment tool;

Fig. 4A shows a LIDAR alignment tool aligned with a rotation axis of the rotor of a wind turbine using a wind turbine alignment interface;

Fig. 4B shows a LIDAR alignment tool aligned with a LIDAR system using a LIDAR alignment interface and a corresponding LIDAR alignment interface;

Fig. 5A-C show the steps of A) aligning a LIDAR alignment tool with a rotation axis of a rotor and recording a rotation axis direction, B) moving the LIDAR alignment tool with the recorded rotation axis direction followed by C) using the LIDAR alignment tool to align a laser beam pointing direction of a LIDAR system with the recorded rotation axis direction;

Fig. 6 shows the method invented as flow-chart; and

Fig. 7 shows an embodiment of the method invented as flow-chart in details.

Fig. 8 shows an embodiment of a LIDAR alignment tool according to the present invention.

Fig. 9 shows an embodiment of a LIDAR alignment tool according to the present invention.

Fig. 10 shows an embodiment of a lid for a LIDAR alignment tool according to the present invention. Detailed Description

Housing

In one embodiment of the present invention, the LIDAR alignment tool further comprises a housing having a base surface and a recessed surface, wherein the base surface defines a length and a width. The length may be more than 100 mm, such as more than 150 mm, such as more than 200 mm, such as 250 mm, such as more than 250 mm, such as more than 300 mm, or such as more than 300 mm, such as more than 350 mm, such as more than 400 mm, such as more than 450 mm, or such as more than 500 mm. The width may be more than 100 mm, such as more than 150 mm, such as 200 mm, such as more than 200 mm, such as more than 250 mm, such as more than 300 mm, or such as more than 300 mm, such as more than 350 mm, such as more than 400 mm, such as more than 450 mm, or such as more than 500 mm. An effect of having a longer or wider device is that the precision of the alignment tool on the rotating member is increased. For example, when the LIDAR alignment tool is placed on the main shaft of the wind turbine, with the length of the LIDAR alignment tool along the main shaft, the position along the main shaft is very precise using a length of for example 250 mm.

Interface(s)

In one embodiment of the present invention, the alignment interface(s) is/are defined by the recessed surface as described above. Alternatively, there may be at least an alignment interface on the recessed surface and at least another interface on the base surface.

In a preferred embodiment of the present invention, the alignment interface(s) and the wind turbine alignment interface(s) (22) is/are the same alignment interface(s). For example, there may be a single interface on the LIDAR alignment tool. Using a single interface may allow for a simple and low cost design. A single interface may further provide a tool that is designed for two surfaces, i.e. a surface on the rotating member (4) of the wind turbine (1 ), and a surface on the LIDAR system (10).

In a more preferred embodiment of the present invention, the LIDAR alignment interface(s) (21 ) is/are a triangular recess. In a most preferred embodiment of the present invention, the triangular recess is defined by an opening angle along the LIDAR alignment tool axis, being between 1 10 and 175 degrees such as being between 125 and 160 degrees, such as being between 140 and 145 degrees, such as 143 degrees. By having a rather wide opening, such as between 140 and 145 degrees, it is possible to place the alignment interface, i.e. the LIDAR alignment tool, directly onto the main shaft of a wind turbine. In other words, the rotating member may be a main shaft of the wind turbine. In other embodiments, the rotating member may be wheels, gears, and/or discs.

Alignment

In one embodiment of the present invention, the LIDAR alignment tool is further configured with means for displaying the direction in real time. This may facilitate easy alignment of the LIDAR system.

Further, easy alignment may be facilitated by the LIDAR alignment tool further comprising a levelling device. The LIDAR alignment tool may have a build-in electronic level guage. In other words, the levelling device may be electronic or analogue, for example a simple spirit level. Having a levelling device on the device, may be particularly practical, in that most turbine shafts are conical. In order to record the exact horizontal centreline, i.e. for example the axis of the main shaft, the LIDAR alignment tool must be precisely vertical above the turbine shaft center line. To place the LIDAR alignment tool precisely vertical above the turbine shaft center line, a levelling device may be used. Using a levelling device may provide information whether the LIDAR alignment tool is level - i.e. for example when the level guage is centered. Once this is achieved, the LIDAR alignment tool is precisely above the center line and thus recording the actual horizontal direction of the turbine shaft. In other words, having a levelling device solves a problem related to precisely positioning the LIDAR tool on a wind turbine main shaft. The LIDAR alignment tool may thus be mechanically aligned with a cylindrical or conical wind turbine main shaft, i.e. a main shaft where the transverse cross section is circular, ellipsoidal or similar in shape. Kit

According to the second aspect of the present invention, the corresponding LIDAR alignment interface (1 1 ) may define an axis that is parallel to a laser beam emitted from the LIDAR system (10). Having such a configuration allows for the laser beam to be pointing along the direction of the main shaft, to which wind speed for a LIDAR system is relevant. This may for example be facilitated by aligning the laser beam with the alignment tool, specifically the LIDAR alignment tool axis.

The method

In relation to the third aspect of the present invention, the LIDAR alignment tool may be the LIDAR alignment tool as described for the first aspect.

In one embodiment of the present invention, the step of placing the LIDAR alignment tool on the rotating member is by using a wind turbine alignment interface (22) on the LIDAR alignment tool. In another embodiment of the present invention, the step of placing the LIDAR alignment tool on the LIDAR system (10) is by using a LIDAR alignment interface (21 ) on the LIDAR alignment tool.

In yet another embodiment of the present invention, the step of placing the LIDAR alignment tool on the LIDAR system (10) is by using the interface (21 ) on the LIDAR alignment tool and a corresponding LIDAR system interface (1 1 ) on the LIDAR system (10).

In a preferred embodiment of the present invention, the step of placing the LIDAR alignment tool (20) on the rotating member (4) is by using a levelling device on the LIDAR alignment tool. As previously described, this is advantageously, for example when the main shaft is conical. In other words, using a levelling device on the LIDAR alignment tool may be practical in order for placing the LIDAR alignment tool precisely in level on a non-circular surface, such as a conical surface, as for example a main shaft.

According to the present invention, the step of adjusting may be performed such that the adjustment direction is matched to the reference direction. The adjustment direction may be matched to the reference direction by using means configured to automatically align the LIDAR system within a tolerance of ±1 .0 degrees and preferably within a tolerance of ±0.5 degrees.

In some embodiments of the present invention, the LIDAR alignment tool (20) communicates with an external position reference system. Operation

In a preferred embodiment of the present invention, the rotation axis (5) is aligned with a LIDAR system (10) within a tolerance of ±0.5 degrees.

Further details

Fig. 1 shows a wind turbine 1 provided with a LIDAR system 10 on an upper surface 3 of the nacelle 2 of the wind turbine 1 and aligned with a rotation axis 5 of the rotor 7 of the wind turbine 1 . The LIDAR system 10 has one or more lasers 12 which emit one or more laser beam 14, here represented as a scan cone for illustrative purposes, for measuring the approaching radial wind speeds and directions in the rotor blade plane. The scan cone represents a beam with typically two beams in a horizontal plane, each beam separated by say 30 degrees on each side of a center line. The cone may also represent more beams; say four or five or even more beams sent out in a plane, such as a horizontal plane. The cone may also represent laser beams sent out as a cone or as lines of a cone. The LIDAR system 10 is aligned using a LIDAR alignment tool 20 of the LIDAR system 10 which is substantially parallel with the rotation axis direction 6 of the rotor 7, whereas the laser beam pointing direction 13 may be substantially parallel with the rotation axis direction 6 within a plane substantially perpendicular to the ground. Fig. 2A-C show an embodiment of the LIDAR alignment tool 20 comprising a wind turbine alignment interface 22 used for alignment with a rotation axis 5 of a rotor 7 having a rotation axis direction 6, a LIDAR alignment interface 21 used for alignment of a laser beam pointing direction 13 of a LIDAR system 10 and a gyroscope 30. The gyroscope 30 comprises a spin axis 31 with a spin axis direction 32. The LIDAR system 10 may comprise a corresponding LIDAR alignment interface 1 1 . The spin axis direction 32 may in one embodiment have a coincidental fixed orientation during the process of alignment.

Fig. 3A-D show different possible shapes of the alignment interface or interfaces 21 , 22 of the LIDAR alignment tool 20. The alignment interface 21 , 22 may be a triangular, a substantially circular or a squared recess or a combination hereof. The wind turbine alignment interface 22 and/or the LIDAR alignment interface 21 may extend partially or all the way across one surface of the LIDAR alignment tool 20. The alignment interfaces 21 , 22 may also be symmetrical around one or more centre planes of the LIDAR alignment tool 20. The wind turbine alignment interface 22 and the LIDAR alignment interface 21 may be the same alignment interface 21 , 22.

Fig. 4A shows the LIDAR alignment tool 20 aligned with a rotation axis 5 of a rotor 7 of a wind turbine 1 using the wind turbine alignment interface 22.

Fig. 4B shows the LIDAR alignment tool 20 aligned with the LIDAR system 10 using the LIDAR alignment interface 21 and the corresponding LIDAR alignment interface 1 1 on the LIDAR system 10. The LIDAR alignment interface 21 and the corresponding LIDAR alignment interface 1 1 may have the substantially same geometrical shape and size.

The LIDAR alignment tool 20 may have an interface with a wide angle on the inner side, which wide angle is so wide or has legs that extend to fit an axis of a large scale wind turbine (say 5 MW or more) will "self-align". A complementary interface may be provided on the LIDAR system so that the LIDAR alignment tool will "self-align" on the LIDAR system.

In an embodiment there may be provide a screen or user interface such as a touch screen configured to operate the gyroscope and a processor inside the LIDAR alignment tool.

Fig. 5A-C show the steps of aligning the LIDAR system 10 with a rotation axis 5 of a rotor 7 of a wind turbine 1 using the LIDAR alignment tool 20. A) First the LIDAR alignment tool 20 is aligned with the rotation axis 5 and records a rotation axis direction 6 constituting a one-to-one wind turbine alignment reference 8 between the spin axis direction 32 and the rotation axis direction 6. B) Then the LIDAR alignment tool 20 is moved from the alignment with the rotation axis 5. C) Then the LIDAR alignment tool 20 is aligned with the LIDAR system 10, and used to align the laser beam pointing direction 13 of the LIDAR system 10 with the recorded rotation axis direction 25. The spin axis direction 32 of the gyroscope 30 may in one embodiment be fixed in a parallel orientation to the rotation axis direction 6 during the alignment.

Fig. 6 shows a flow chart to explain the inventive method of aligning a LIDAR system 10 to a rotation axis 5 of a rotor 7. The first step S1 comprising an aligning of the LIDAR alignment tool 20 with a rotation axis 5, using the wind turbine alignment interfaces 22 to align the LIDAR alignment tool 20 with a rotation axis 5 of a rotor 7.

The second step S2 comprising a recording of the spin axis direction 32 of the gyroscope 30 within the LIDAR alignment tool 20 so that a rotation axis direction 6 of a rotor 7 is recorded by the LIDAR alignment tool 20.

The third step S3 comprising an aligning of the LIDAR alignment tool 20 with a LIDAR system 10 by using the LIDAR alignment interface 21 .

The fourth step S4 comprising an adjusting of a laser beam pointing direction 13 of a LIDAR system 10 in accordance with the recorded rotation axis direction 25 of a rotor 7 recorded by the LIDAR alignment tool 20.

Fig. 7 shows a flow chart to explain one embodiment of the inventive method of aligning a LIDAR system 10 to a rotation axis 5 of a rotor 7 in more details.

In a first step S1 , the LIDAR alignment tool 20 is placed on a wind turbine 1 using the wind turbine alignment interface 22 to align the LIDAR alignment tool 20 with the rotation axis 5.

LIDAR systems 10 mounted on wind turbines 1 with a main shaft 4, turbine shaft or another shaft which is known to have a centre axis being the same as or parallel to the rotation axis 5 of the rotor 7 are preferably aligned by aligning the wind turbine alignment interface 22 of the LIDAR alignment tool 20 with the shaft.

LIDAR systems 10 mounted on wind turbines 1 without a main shaft 4, turbine shaft or another shaft known to have a centre axis being the same as or parallel to the rotation axis 5 of the rotor 7 are preferably aligned by aligning the wind turbine alignment interface 22 of the LIDAR alignment tool 20 with means on or in the wind turbine 1 known to be perpendicular to the rotation axis 5 of the rotor 7 as for example a rotor brake disc.

In a second step S2, the gyroscope 30 within the LIDAR alignment tool 20 may be activated and thereby obtaining a substantially fixed spin axis 31 with a substantially fixed spin axis direction 32 while the LIDAR alignment tool 20 is aligned with a rotation axis 5. This is if the gyroscope 30 within the LIDAR alignment tool 20 was not already activated before aligning the LIDAR alignment tool 20 with the rotation axis 5 of the rotor 7. This might be an advantage in order to avoid that forces from the gyroscope 30 are applied to the bearings as well as other parts of fixture of the gyroscope 30 causing unnecessary wear and tear reducing the lifetime of the LIDAR alignment tool 20.

In a third step S3 the LIDAR alignment tool 20 may be reset thereby obtaining a fixed spin axis direction 32 substantially parallel to the rotation axis 5 of the rotor 7.

In an alternative embodiment, an external trigger is configured to reset the alignment tool. This will prevent having to stop and restart the system.

In an embodiment the LIDAR alignment tool 20 may be configured with an external trigger configured so that the LIDAR alignment tool 20 may be reset to "0 degrees". This is advantageous to allow for the LIDAR alignment tool 20 to be positioned, started and subsequently be zeroed.

In a fourth step S4 the rotation axis direction 6 is recorded within the LIDAR alignment tool 20 by resetting the LIDAR alignment tool 20 and thereby recording a one-to-one wind turbine alignment reference 8 between the spin axis direction 32 and the rotation axis direction 6. A display 24 may show 0.0^°.

In a fifth step S5 the LIDAR alignment tool 20 is removed from the wind turbine 1 .

In a sixth step S6 the LIDAR alignment tool 20 is placed on the LIDAR system 10 using the LIDAR alignment interface 21 . A corresponding LIDAR alignment interface 1 1 on the LIDAR system 10 is used if available. The LIDAR alignment interface 21 and the corresponding LIDAR alignment interface 1 1 may centralise the LIDAR alignment tool

20 on a surface of the LIDAR system 10 so that the recorded rotation axis direction 25 is parallel with the laser beam pointing direction 13.

In a seventh step S7 the laser beam pointing direction 13 of the LIDAR system 10 is adjusted in accordance with the stored rotation axis direction 6. The display 24 may again show 0.0^°.

Fig. 8A and Fig. 8B shows an embodiment of a LIDAR alignment tool according to the present invention from a top perspective and bottom perspective, respectively. The alignment tool comprises a housing or a structure, having a base surface, here defined by a rim of the structure, and a recessed surface. The recessed surface has here a triangular recess. The alignment tool as shown is for example made in aluminium. From 8B, it can be seen that the housing, is configured for holding a device, in this case the base surface, for example a device such as the gyroscope, and/or a levelling device. Fig. 9A and Fig. 9B shows an embodiment of a LIDAR alignment tool according to the present invention from a side perspective and a top perspective, respectively. In Fig. 9A, it is shown that the LIDAR alignment tool has a triangular recess. The triangular recess is defined by an opening angle along the LIDAR alignment tool axis, being between 1 10 and 175 degrees such as being between 125 and 160 degrees, such as being between 140 and 145 degrees, such as 143 degrees. Here, the angle of 143 degrees is shown. Accordingly, the angle from the opening to the base surface is 18.5 degrees as indicated in Fig. 9A. The base surface is here rectangular, but could be any suitable shape, such as for example square. The base surface may as shown is here also a recessed surface, as can be seen in Fig. 9A. In Fig. 9B, the base surface defines a plane having a length and a width. It can be seen that the length of the base plate is 250 mm, and the width of the base plate is 200 mm. The length of the base plate is parallel to the alignment tool axis. The alignment tool axis is here the line of symmetry along center line of the base plate. According to the present invention, the alignment interface - here, a single interface, being the triangular recess, defines the alignment tool axis. The triangular recess is triangular in the sense that it is

substantially triangular, here due to machining. As it can be seen, the top of the triangle is flat, in particular with a width of 10 mm. Thus, the alignment tool axis is along the valley of the recess.

Fig. 10 shows an embodiment of a lid for a LIDAR alignment tool according to the present invention. The lid designed to hold the gyroscope and/or other devices, such as for example a levelling device. Using the lid facilitates the housing of the LIDAR alignment tool is able to hold the gyroscope and/or other devices, such as for example a levelling device.

List of references

Part Description

1 Wind turbine

2 Nacelle

3 Upper surface

4 Main shaft

5 Rotation axis

6 Rotation axis direction 7 Rotor

8 One-to-one wind turbine alignment reference

10 LIDAR system

1 1 Corresponding LIDAR alignment interface

12 Laser

13 Laser beam pointing direction

14 Laser beam scan cone

16 One-to-one LIDAR alignment reference

20 LIDAR alignment tool

21 LIDAR alignment interface

22 Wind turbine alignment interface

24 Display

25 Recorded rotation axis direction

30 Gyroscope

31 Spin axis

32 Spin axis direction

Further details of the present invention are described by the following items:

ITEMS

1 . A method of aligning a LIDAR system (10) with a rotation axis (5) of a rotor (7) of a wind turbine (1 ), using a one-to-one wind turbine alignment reference (8) between the wind turbine (1 ) and the rotation axis (5) and a LIDAR alignment tool (20) comprising:

- at least a wind turbine alignment interface (22) configured for aligning the LIDAR alignment tool (20) with a rotation axis (5) of a wind turbine (1 ),

- at least a LIDAR alignment interface (21 ) configured for aligning the LIDAR alignment tool (20) with a LIDAR system (10) so that a laser beam pointing direction (13) of a

LIDAR system (10) can be aligned with the LIDAR alignment tool (20),

- the LIDAR alignment tool (20) comprises a gyroscope (30) configured for obtaining a substantially fixed spin axis (31 ), which LIDAR alignment tool (20) is configured to record a spin axis direction (32) of the fixed spin axis (31 ) constituting a one-to-one alignment reference (8, 16) between the spin axis direction (32) and each of the least wind turbine alignment interface (22) and the least LIDAR alignment interface (21 ), the method comprising: - aligning the LIDAR alignment tool (20) with a rotation axis (5), using the wind turbine alignment interfaces (22) to align the LIDAR alignment tool (20) with a rotation axis (5) of a rotor (7),

- recording the spin axis direction (32) of the gyroscope (30) within the LIDAR alignment tool (20) so that a rotation axis direction (6) of a rotor (7) is recorded by the LIDAR alignment tool (20),

- aligning the LIDAR alignment tool (20) with a LIDAR system (10) by using the LIDAR alignment interface (21 ),

- adjusting the direction (13) of a LIDAR system (10) in accordance with the recorded rotation axis direction (25) of a rotor (7) recorded by the LIDAR alignment tool (20), thereby aligning a LIDAR system (10) to a rotation axis (5) of a rotor (7).

2. A method of aligning a LIDAR system (10) according to iteml , further comprising the step of resetting the LIDAR alignment tool (20) while the LIDAR alignment tool (20) is aligned with a rotation axis (5).

3. A method of aligning a LIDAR system (10) according to iteml or 2, using the same alignment interface as the LIDAR alignment interface (21 ) and the wind turbine alignment interface (22).

4. A method of aligning a LIDAR system (10) according to any of iteml to 3, using a LIDAR alignment tool (20) configured to display the recorded rotation axis direction (25) of a rotor (7) in real time.

5. A method of aligning a LIDAR system (10) according to any of iteml to 4, using means configured to automatically align a LIDAR system (10) to the recorded rotation axis direction (25) of a rotor (7) within a tolerance of ±1 .0 degrees and preferably within a tolerance of ±0.5 degrees.

6. A method of aligning a LIDAR system (10) according to any of the preceding items, using the LIDAR alignment interface (21 ) and a corresponding LIDAR alignment interface (1 1 ) to align the LIDAR alignment tool (20) so that the recorded rotation axis direction (25) is parallel with a laser beam pointing direction (13).

7. A method of aligning a LIDAR system (10) according to any of the preceding items, using a LIDAR alignment tool (20) which communicates with an external position reference system.

8. A LIDAR alignment tool (20) comprising:

Claims

- at least a LIDAR alignment interface (21 ) configured for aligning the LIDAR alignment tool (20) with a LIDAR system (10) so that a laser beam pointing direction (13) of a LIDAR system (10) can be aligned with the LIDAR alignment tool (20),

wherein the LIDAR alignment tool (20) comprises a gyroscope (30) configured for obtaining a substantially fixed spin axis (31 ), which LIDAR alignment tool (20) is configured to record a spin axis direction (32) of the fixed spin axis (31 ) constituting a one-to-one alignment reference (8, 16) between the spin axis direction (32) and each of the least wind turbine alignment interface (22) and the least LIDAR alignment interface (21 ).

9. A LIDAR alignment tool (20) according to item 8 wherein the LIDAR alignment interface (21 ) and the wind turbine alignment interface (22) are the same alignment interface.

10. A LIDAR alignment tool (20) according to item 8 or 9 wherein the LIDAR alignment interface (21 ) is a triangular recess.

1 1 . A LIDAR alignment tool (20) according to any of item 8 to 10 configured with means for displaying the recorded rotation axis direction (25) of a rotor (7) in real time.

12. A kit of a LIDAR alignment tool (20) according to any of item7 to 10 and a LIDAR system (10) configured for being aligned with a rotation axis (5) of a rotor (7) of a wind turbine (1 ) using the LIDAR alignment tool (20) by having a corresponding LIDAR alignment interface (1 1 ).

13. Operation of a wind turbine (1 ) with a rotation axis (5) aligned with a LIDAR system (10), which alignment of rotation axis (5) and LIDAR system (10) is performed by a LIDAR alignment tool (20) according to any of item8 to 12 or by a method of aligning according to any of iteml to 7.

14. Operation of a wind turbine (1 ) according to iteml 3 wherein a rotation axis (5) is aligned with a LIDAR system (10) within a tolerance of ±0.5 degrees.

Claims

1 . A LIDAR alignment tool (20), comprising:

- one or more wind turbine alignment interface(s) (22), the alignment interface(s) (22) defining a LIDAR alignment tool axis, wherein at least one of said interfaces (22) is configured for being mechanically aligned with a rotating member (4) of a wind turbine (1 );

- a gyroscope (30) mechanically fixed to the LIDAR alignment tool (20) and configured for providing a direction (32), such that the direction (32) is referenced with respect to a direction of the alignment tool axis; and

- one or more LIDAR alignment interfaces(s) (21 ), wherein at least one of said LIDAR alignment interfaces (21 ) is configured for being mechanically aligned with a LIDAR system (10).

The LIDAR alignment tool according to claim 1 , further comprising a housing having a base surface and a recessed surface, wherein the base surface defines a length and a width.

The LIDAR alignment tool (20) according to claim 2, wherein the length is more than 100 mm, such as more than 150 mm, such as more than 200 mm, such as 250 mm, such as more than 250 mm, such as more than 300 mm, or such as more than 300 mm, such as more than 350 mm, such as more than 400 mm, such as more than 450 mm, or such as more than 500 mm.

The LIDAR alignment tool (20) according to any of the claims 2-3, wherein the width is more than 100 mm, such as more than 150 mm, such as 200 mm, such as more than 200 mm, such as more than 250 mm, such as more than 300 mm, or such as more than 300 mm, such as more than 350 mm, such as more than 400 mm, such as more than 450 mm, or such as more than 500 mm.

The LIDAR alignment tool (20) according to claim 2, wherein the alignment interface(s) (21 ) is/are defined by the recessed surface.

6. The LIDAR alignment tool (20) according to any of the preceding claims,

wherein the LIDAR alignment interface(s) (21 ) and the wind turbine alignment interface(s) (22) is/are the same alignment interface(s).

7. The LIDAR alignment tool (20) according to any of the preceding claims, wherein the LIDAR alignment interface(s) (21 ) is/are a triangular recess.

8. The LIDAR alignment tool (20) according to any of the preceding claims, wherein the triangular recess is defined by an opening angle along the LIDAR alignment tool axis, being between 1 10 and 175 degrees such as being between 125 and 160 degrees, such as being between 140 and 145 degrees, such as 143 degrees.

9. The LIDAR alignment tool (20) according to any of the preceding claims, wherein the rotating member (4) is a main shaft of the wind turbine. 10. The LIDAR alignment tool (20) according to any of the preceding claims, wherein the LIDAR alignment tool is further configured with means for displaying the direction in real time.

1 1 . The LIDAR alignment tool (20) according to any of the preceding claims, wherein the LIDAR alignment tool further comprising a levelling device.

12. A kit of a LIDAR alignment tool (20) according to any of the preceding claims and a LIDAR system (10) configured for being mechanically aligned with the LIDAR alignment tool (20) by having a corresponding LIDAR alignment interface (1 1 ).

13. The kit according to claim 12, wherein the corresponding LIDAR alignment interface (1 1 ) defines an axis that is parallel to a laser beam emitted from the LIDAR system (10).

14. A method for aligning a LIDAR system (10) to a rotation axis (5) of a wind turbine, comprising the steps of:

- providing a LIDAR alignment tool (20) configured for providing a

direction (32);

- placing the LIDAR alignment tool (20) on a rotating member (4) of the wind turbine, the rotating member defining the rotation axis (5); - obtaining and recording the direction (32) as a reference direction from the LIDAR alignment tool (20) such that the reference direction is referenced with respect to the direction of the rotation axis;

- moving the LIDAR alignment tool (20) from the rotation axis and placing it onto the LIDAR system (10), thereby obtaining an adjustment direction; and

- adjusting the LIDAR system (10) according to the adjustment direction and relative to the reference direction,

thereby aligning the LIDAR system (10) to the rotation axis (5) of the wind turbine.

15. The method for aligning a LIDAR system, according to claim 14, wherein the LIDAR alignment tool is the LIDAR alignment tool according to any of the claims 1 -1 1 .

16. The method according to any of the preceding claims 14-15, wherein the step of placing the LIDAR alignment tool on the rotating member is by using a wind turbine alignment interface (22) on the LIDAR alignment tool.

17. The method according to any of the preceding claims 14-16, wherein the step of placing the LIDAR alignment tool on the LIDAR system (10) is by using a LIDAR alignment interface (21 ) on the LIDAR alignment tool.

18. The method according to any of the preceding claims 14-17, wherein the step of placing the LIDAR alignment tool on the LIDAR system (10) is by using the interface (21 ) on the LIDAR alignment tool and a corresponding LIDAR system interface (1 1 ) on the LIDAR system (10).

19. The method according to any of the preceding claims 14-18, wherein the step of placing the LIDAR alignment tool on the rotating member is by using a levelling device on the LIDAR alignment tool.

20. The method according to any of the preceding claims 14-19, wherein the step of adjusting is performed such that the adjustment direction is matched to the reference direction.

21 . The method according to claim 20, wherein the adjustment direction is matched to the reference direction by using means configured to automatically align the LIDAR system within a tolerance of ±1 .0 degrees and preferably within a tolerance of ±0.5 degrees.

22. The method according to any of the preceding claims 14-21 , wherein the LIDAR alignment tool (20) communicates with an external position reference system.

23. Operation of a wind turbine (1 ) with a rotation axis (5) aligned with a LIDAR system (10), which alignment of rotation axis (5) and LIDAR system (10) is performed by a LIDAR alignment tool (20) according to any of the claims to 1 - 1 1 and/or by a method of aligning according to any of the claims 14 to 22.

24. Operation of a wind turbine (1 ) according to claim 23, wherein the rotation axis (5) is aligned with a LIDAR system (10) within a tolerance of ±0.5 degrees.