Methods and systems for mounting wind turbine blades to hubs

Abstract

The present disclosure relates to methods for mounting wind turbine blades on hubs. The methods comprise mounting one or more winches on one of the blade and the hub, attaching one or more cables for the winches on the other of the blade and the hub and hoisting the wind turbine blade with a crane and positioning the wind turbine blade in proximity to the hub. The methods further comprise connecting the cables to the winches, sensing movement of the blade relative to the hub and activating the winches and pulling the cables to synchronize a motion of the blade and the hub and to guide the blade towards the hub in a first direction. The methods further comprise approaching the hub with the blade while using one or more additional actuators capable of pushing or pulling the blade away from the hub to control movement of the blade towards the hub. The present disclosure further relates to wind turbine blades configured for such methods and systems comprising a hub and a wind turbine blade.

Description

GENERAL ELECTRIC RE OVABLES ESPANA S.L. DECEMBER 20, 2024 GE 701161-WO-1; 701194-WO-1 P5523PC00METHODS AND SYSTEMS FOR MOUNTING WIND TURBINE BLADES TO HUBSFIELD

[0001] The present disclosure relates to mounting of blades on a wind turbine hub. The present disclosure also relates to wind turbine blades and systems that aid in the mounting of wind turbine blades on a wind turbine hub.BACKGROUND

[0002] Modern wind turbines are commonly used to supply electricity into the electrical grid. Wind turbines of this kind generally comprise a tower and a rotor arranged on the tower. The rotor, which typically comprises a hub and a plurality of blades, is set into rotation under the influence of the wind on the blades. Said rotation generates a torque that is normally transmitted through a rotor shaft to a generator, either directly ("directly driven" or "gearless") or through the use of a gearbox. This way, the generator produces electricity which can be supplied to the electrical grid.

[0003] The wind turbine hub may be rotatably coupled to a front of the nacelle. The wind turbine hub may be connected to a rotor shaft, and the rotor shaft may then be rotatably mounted in the nacelle using one or more rotor shaft bearings arranged in a frame inside the nacelle. The nacelle is a housing arranged on top of a wind turbine tower that contains and protects e.g. the gearbox (if present) and the generator and, depending on the wind turbine, further components such as a power converter, and auxiliary systems.

[0004] Wind turbine blades are generally coupled to the hub by a pitch bearing. A pitch bearing typically comprises an inner ring and an outer ring, and usually a plurality of rolling or roller elements between the inner and outer ring. A wind turbine blade may be attached either to the inner ring or to the outer ring, whereas the hub may be attached to the other of the inner and outer rings. The attachment may for example be performed with nuts and bolts.

[0005] The installation of wind turbine blades has become more and more of a challenging task due to the general tendency to increase the size and weight of modern wind turbine blades. Blades of modern wind turbines may be more than 70 or 80 meters long, or even morethan 100 meters long. During installation, the wind turbine blades need to be hoisted towards the rotor hub.

[0006] A known way of mounting a wind turbine includes the steps of transporting the different elements to the site of the wind turbine, assembling the tower sections and the tower, lifting the wind turbine nacelle with a large crane and mounting the nacelle on top of the tower. Then the wind turbine rotor hub can be lifted with the crane and mounted to a rotor shaft and / or the nacelle. Alternatively, the hub can be mounted to the nacelle and then the nacelle-hub assembly can be hoisted.

[0007] Afterwards, one or more blades are mounted to the wind turbine rotor hub. The rotor hub generally comprises a plurality of annular mounting flanges. Pitch bearings can be arranged with the mounting flanges. The blade can comprise a plurality of fasteners, such as bolts, or pins or studs at its blade root. During installation, these fasteners are to be fitted into openings in the mounting flange or pitch bearing on the hub.

[0008] It is also known to hoist a complete rotor assembly, i.e. the hub with the plurality of blades, and mount it on e.g. the nacelle. But in order to mount a complete rotor assembly, a large surface area is required, which is typically not available e.g. in the case of offshore wind turbines. Further, the mass of a complete rotor assembly is significant and may exceed the crane’s capabilities or the capabilities of the tools for fixing the hub.

[0009] It is further known to mount blades individually. It is known to mount each of the plurality of blades substantially horizontally (e.g. between -30° - +30° with respect to a horizontal plane) or substantially vertically.

[0010] Wind is inherently variable and winds from different directions, turbulent winds, and wind gusts can act on the wind turbine blade during hoisting and may provoke sudden movements and possibly oscillations of the blade during the hoisting operation. Fitting the blade to a hub may thus be complicated and time-consuming.

[0011] For offshore installations, the installation can be even more complicated. The vessel carrying a crane may move under wind and wave forces. Also, the wind turbine tower and the nacelle mounted on top of the tower can move under wind and wave forces. Wind turbine farms can also be situated in remote sites, e.g. on hill-tops and typically in these places the lifting of the wind turbine blade may be subject to high winds.

[0012] Frequently, difficulties can arise during the lifting operation due to oscillations of both the blade and the hub. In order to perform the installation of the blade, manual aid is often required e.g. the blade is stabilized with ropes. This can lead to an increase of the risk for the operators.

[0013] Oscillations during hoisting operations may also lead to possible damage to the wind turbine blade or to other parts of the wind turbine. If for example a sudden movement occurs when a wind turbine blade is close to the hub, parts or components may be damaged e.g. the blade, a pitch bearing, or blade fasteners.

[0014] The present disclosure provides systems and methods to at least partially overcome some of the aforementioned drawbacks.SUMMARY

[0015] In an aspect of the present disclosure, a method for mounting a wind turbine blade on a hub is provided. The method comprises mounting one or more winches on one of the blade and the hub and attaching one or more cables for the winches on the other of the blade and the hub. The method then comprises hoisting the wind turbine blade with a crane and positioning the wind turbine blade in proximity to the hub and connecting the cables to the winches. Then the method comprises sensing movement of the blade relative to the hub and activating the winches and pulling the cables to synchronize a motion of the blade and the hub and to guide the blade towards the hub in a first direction. Subsequently, the blade approaches the hub while using one or more additional actuators capable of pushing or pulling the blade away from the hub to control movement of the blade towards the hub.

[0016] According to this aspect, the installation of a wind turbine blade on a hub may be enhanced, enabling the installation process to be carried out during relatively harsh weather conditions. The method allows synchronization of the movements of blade and hub and damping of the blade-to-hub movement to a level where the blade can securely approach the hub and be mounted on it. Movement of the blade in different directions may be independently controlled, reducing relative motion of the blade with respect to the hub.

[0017] The cables and the winches may be used to synchronize the movement of the blade and hub. The winches and cable can act by pulling the blade towards the hub as it moves away. This action not only allows for a first synchronization of movements, but it can also better align the blade with the hub. In the opposite direction of movement, the actuation of the winches is limited. Once the motion between the blade and the hub has been synchronized, the additional actuators may ensure that the contact between the blade and the hub is carried out in a controlled manner, dampening the blade in a direction opposite to the direction in which the blade approaches the hub and preventing the blade and the hub from colliding and being damaged. The blade approaching the hub may be carried out in different ways as set out in the present disclosure.

[0018] Throughout the present disclose, a cable may be regarded as a tension element i.e. an element which may be used to transmit a tension force. “Cable” as used herein should be understood to encompass any of wire, rope, chain, cord, line, or strand. These terms may be used interchangeable.

[0019] Throughout the present disclosure, an additional actuator may be regarded as an element which may be used to actively dampen or restrict motion of the blade in a longitudinal direction of the blade as it approaches the hub. The additional actuator thus may be configured to push the blade away from the hub and dampen movement of the blade in a direction opposite to the direction in which the blade approaches the hub.

[0020] In another aspect of the present disclosure, a wind turbine blade is provided. The wind turbine blade comprises one or more linear actuators mounted on the blade, wherein the linear actuators carry cables, and wherein the cables are configured to be connected to winches mounted on the hub.

[0021] In accordance with a yet a further aspect of the present disclosure, a system is provided. The system comprises a wind turbine blade comprising one or more linear actuators and a hub comprising one or more winches. The linear actuators carry cables, and wherein the linear actuators are removably mounted on the blade, and the cables are configured to be connected to the winches mounted on the hub.

[0022] In a further aspect of the present disclosure, a kit is provided. The kit comprises one or more winches configured for being mounted on one of a wind turbine blade or a wind turbine hub, one or more cables configured to be connected to the winches, the cables configured for being attached to the other of the blade and the hub, and one or more lineal actuators for being removably mounted on the blade and configured to carry the cables.

[0023] Additional objects, advantages and features of embodiments of the present disclosure will become apparent to those skilled in the art upon examination of the description, or may be learned by practice.BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 schematically illustrates a perspective view of one example of a wind turbine;

[0025] Figure 2 illustrates an example of a hub and a nacelle of a wind turbine;

[0026] Figure 3 shows a flow chart of an example of a method for mounting a wind turbine blade to a hub;

[0027] Figures 4a - 4d schematically show steps of the method for mounting a wind turbine blade to a hub according to an example of the present disclosure;

[0028] Figures 5a - 5f schematically show steps of a method for mounting a wind turbine blade to a hub according to another example of the present disclosure;

[0029] Figure 5g schematically shows an additional actuator according to an example of the present disclosure; and

[0030] Figure 6 schematically shows a winch mounted on a hub and one or more cables attached on the blade according to a further example of the present disclosure.DETAILED DESCRIPTION OF EXAMPLES

[0031] Reference will now be made in detail to embodiments of the disclosure, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation, not as a limitation. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the teaching. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims and their equivalents.

[0032] Figure 1 is a perspective view of an example of a wind turbine 10. In the example, the wind turbine 10 is a horizontal-axis wind turbine. Alternatively, the wind turbine 10 may be a vertical-axis wind turbine. In the example, the wind turbine 10 includes a tower 15 that extends from a support system 14 on a ground 12, a nacelle 16 mounted on tower 15, and a rotor 18 that is coupled to nacelle 16. The rotor 18 includes a rotatable hub 20 and at least one rotor blade 22 coupled to and extending outward from the hub 20. In the example, the rotor 18 has three rotor blades 22. In an alternative embodiment, the rotor 18 includes more or less than three rotor blades 22. The tower 15 may be fabricated from tubular steel to define a cavity (not shown in figure 1) between a support system 14 and the nacelle 16. In an alternative embodiment, the tower 15 is any suitable type of a tower having any suitable height. According to an alternative, the tower can be a hybrid tower comprising a portion made of concrete and a tubular steel portion. Also, the tower can be a partial or full lattice tower.

[0033] The rotor blades 22 are spaced about the hub 20 to facilitate rotating the rotor 18 to enable kinetic energy to be transferred from the wind into usable mechanical energy, and subsequently, electrical energy. The rotor blades 22 are mated to the hub 20 by coupling a blade root portion 24 to the hub 20 at a plurality of load transfer regions 26. The load transferregions 26 may have a hub load transfer region and a blade load transfer region (both not shown in figure 1). Loads induced to the rotor blades 22 are transferred to the hub 20 via the load transfer regions 26.

[0034] In examples, the rotor blades 22 may have a length ranging from about 15 meters (m) to about 90 m or more. Rotor blades 22 may have any suitable length that enables the wind turbine 10 to function as described herein. As wind strikes the rotor blades 22 from a wind direction 28, the rotor 18 is rotated about a rotor axis 30. As the rotor blades 22 are rotated and subjected to centrifugal forces, the rotor blades 22 are also subjected to various forces and moments. As such, the rotor blades 22 may deflect and / or rotate from a neutral, or non-deflected, position to a deflected position.

[0035] Moreover, a pitch angle of the rotor blades 22, i.e., an angle that determines an orientation of the rotor blades 22 with respect to the wind direction, may be changed by a pitch system 32 to control the load and power generated by the wind turbine 10 by adjusting an angular position of at least one rotor blade 22 relative to wind vectors. Pitch axes 34 of rotor blades 22 are shown. During operation of the wind turbine 10, the pitch system 32 may particularly change a pitch angle of the rotor blades 22 such that the angle of attack of (portions of) the rotor blades are reduced, which facilitates reducing a rotational speed and / or facilitates a stall of the rotor 18.

[0036] In the example, a blade pitch of each rotor blade 22 is controlled individually by a wind turbine controller 36 or by a pitch control system 80. Alternatively, the blade pitch for all rotor blades 22 may be controlled simultaneously by said control systems.

[0037] Further, in the example, as the wind direction 28 changes, a nacelle 16 may be rotated about a yaw axis 38 to position the rotor blades 22 with respect to wind direction 28.

[0038] In the example, the wind turbine controller 36 is shown as being centralized within the nacelle 16, however, the wind turbine controller 36 may be a distributed system throughout the wind turbine 10, on the support system 14, within a wind farm, and / or at a remote-control center. The wind turbine controller 36 includes a processor 40 configured to perform the methods and / or steps described herein. Further, many of the other components described herein include a processor.

[0039] As used herein, the term “processor” is not limited to integrated circuits referred to in the art as a computer, but broadly refers to a controller, a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific, integrated circuit, and other programmable circuits, and these terms are used interchangeably herein. It should be understood that a processor and / or a control system can also include memory, input channels, and / or output channels.

[0040] Figure 2 is an enlarged sectional view of a portion of the wind turbine 10. In the example, the wind turbine 10 includes the nacelle 16 and the rotor 18 that is rotatably coupled to the nacelle 16. More specifically, the hub 20 of the rotor 18 is rotatably coupled to an electric generator 42 positioned within the nacelle 16 by the main shaft 44, a gearbox 46, a high-speed shaft 48, and a coupling 50. In the example, the main shaft 44 is disposed at least partially coaxial to a longitudinal axis (not shown) of the nacelle 16. A rotation of the main shaft 44 drives the gearbox 46 that subsequently drives the high-speed shaft 48 by translating the relatively slow rotational movement of the rotor 18 and of the main shaft 44 into a relatively fast rotational movement of the high-speed shaft 48. The latter is connected to the generator 42 for generating electrical energy with the help of a coupling 50. Furthermore, a transformer 90 and / or suitable electronics, switches, and / or inverters may be arranged in the nacelle 16 in order to transform electrical energy generated by the generator 42 having a voltage between 400V to 6000 V e.g. of about 3100 V into electrical energy having medium voltage, e.g. 10 -70 KV e.g. 66 KV. Said electrical energy is conducted via power cables from the nacelle 16 into the tower 15.

[0041] The gearbox 46, generator 42 and transformer 90 may be supported by a main support structure frame of the nacelle 16, optionally embodied as a main frame 52. The gearbox 46 may include a gearbox housing that is connected to the main frame 52 by one or more torque arms 99. In the example, the nacelle 16 also includes a main forward support bearing 60 and a main aft support bearing 62. Furthermore, the generator 42 can be mounted to the main frame 52 by decoupling support means 54, in particular in order to prevent vibrations of the generator 42 to be introduced into the main frame 52 and thereby causing a noise emission source.

[0042] Optionally, the main frame 52 is configured to carry the entire load caused by the weight of the rotor 18 and components of the nacelle 16 and by the wind and rotational loads, and furthermore, to introduce these loads into the tower 15 of the wind turbine 10. The rotor shaft 44, generator 42, gearbox 46, high speed shaft 48, coupling 50, and any associated fastening, support, and / or securing device including, but not limited to, main frame 52, and forward support bearing 60 and aft support bearing 62, are sometimes referred to as a drive train 64.

[0043] In some examples, the wind turbine may be a direct drive wind turbine without gearbox 46. Generators 42 operate at the same rotational speed as the rotor 18 in direct drive wind turbines. They therefore generally have a much larger diameter than generators used in wind turbines having a gearbox 46 for providing a similar amount of power than a wind turbine with a gearbox.

[0044] The nacelle 16 may also include a yaw drive mechanism 56 that may be used to rotate the nacelle 16 and thereby also the rotor 18 about the yaw axis 38 to control the perspective of the rotor blades 22 with respect to the wind direction 28.

[0045] For positioning the nacelle 16 appropriately with respect to the wind direction 28, the nacelle 16 may also include at least one meteorological measurement system 58 which may include a wind vane and anemometer. The meteorological measurement system 58 can provide information to the wind turbine controller 36 that may include wind direction 28 and / or wind speed. In the example, the pitch system 32 is at least partially arranged as a pitch assembly 66 in the hub 20. The pitch assembly 66 includes one or more pitch drive systems 68 and at least one sensor 70. Each pitch drive system 68 is coupled to a respective rotor blade 22 (shown in figure 1) for modulating the pitch angle of a rotor blade 22 along the pitch axis 34. Only one of three pitch drive systems 68 is shown in figure 2.

[0046] In the example, the pitch assembly 66 includes at least one pitch bearing 72 coupled to hub 20 and to a respective rotor blade 22 (shown in figure 1) for rotating the respective rotor blade 22 about the pitch axis 34. The pitch drive system 68 includes a pitch drive motor 74, a pitch drive gearbox 76, and a pitch drive pinion 78. The pitch drive motor 74 is coupled to the pitch drive gearbox 76 such that the pitch drive motor 74 imparts mechanical force to the pitch drive gearbox 76. The pitch drive gearbox 76 is coupled to the pitch drive pinion 78 such that the pitch drive pinion 78 is rotated by the pitch drive gearbox 76. The pitch bearing 72 is coupled to pitch drive pinion 78 such that the rotation of the pitch drive pinion 78 causes a rotation of the pitch bearing 72.

[0047] Pitch drive system 68 is coupled to the wind turbine controller 36 for adjusting the pitch angle of a rotor blade 22 upon receipt of one or more signals from the wind turbine controller 36. In the example, the pitch drive motor 74 is any suitable motor driven by electrical power and / or a hydraulic system that enables pitch assembly 66 to function as described herein. Alternatively, the pitch assembly 66 may include any suitable structure, configuration, arrangement, and / or components such as, but not limited to, hydraulic cylinders, springs, and / or servomechanisms. In certain embodiments, the pitch drive motor 74 is driven by energy extracted from a rotational inertia of hub 20 and / or a stored energy source (not shown) that supplies energy to components of the wind turbine 10.

[0048] The pitch assembly 66 may also include one or more pitch control systems 80 for controlling the pitch drive system 68 according to control signals from the wind turbine controller 36, in case of specific prioritized situations and / or during rotor 18 overspeed. In the example, the pitch assembly 66 includes at least one pitch control system 80 communicatively coupled to a respective pitch drive system 68 for controlling pitch drive system 68independently from the wind turbine controller 36. In the example, the pitch control system 80 is coupled to the pitch drive system 68 and to a sensor 70. During normal operation of the wind turbine 10, the wind turbine controller 36 may control the pitch drive system 68 to adjust a pitch angle of rotor blades 22.

[0049] According to an embodiment, a power generator 84, for example comprising a battery and electric capacitors, is arranged at or within the hub 20 and is coupled to the sensor 70, the pitch control system 80, and to the pitch drive system 68 to provide a source of power to these components. In the example, the power generator 84 provides a continuing source of power to the pitch assembly 66 during operation of the wind turbine 10. In an alternative embodiment, power generator 84 provides power to the pitch assembly 66 only during an electrical power loss event of the wind turbine 10. The electrical power loss event may include power grid loss or dip, malfunctioning of an electrical system of the wind turbine 10, and / or failure of the wind turbine controller 36. During the electrical power loss event, the power generator 84 operates to provide electrical power to the pitch assembly 66 such that pitch assembly 66 can operate during the electrical power loss event.

[0050] In the example, the pitch drive system 68, the sensor 70, the pitch control system 80, cables, and the power generator 84 are each positioned in a cavity 86 defined by an inner surface 88 of hub 20. In an alternative embodiment, said components are positioned with respect to an outer roof surface of hub 20 and may be coupled, directly or indirectly, to the outer roof surface.

[0051] Figure 3 shows a flow chart of a method 300 for mounting a wind turbine blade 22 on a hub 20 according to an example of the present disclosure.

[0052] Figures 4a - 4d schematically show steps of the method 300 for mounting a wind turbine blade 22 on a hub 20 according to an example of the present disclosure. The figures schematically show a system 100 comprising a wind turbine blade comprising one or more additional actuators 130 removably mounted on the blade and a hub 20 comprising one or more winches 120. The additional actuators 130 are configured for pushing the blade away from the hub and carry cables 110 configured to be connected to the winches 120 mounted on the hub 20.

[0053] The method 300 for mounting a wind turbine blade on a hub comprises, at step 302, mounting one or more winches 120 on one of the blade 22 and the hub 20, at step 304, attaching one or more cables 110 for the winches 120 on the other of the blade 22 and the hub 20, and, at step 306, hoisting the wind turbine blade 22 with a crane and positioning the wind turbine blade 22 in proximity to the hub 20.

[0054] In some examples, the system may comprise one or more retention systems configured to fix the one or more cables 110 to the blade 22 or to the hub 20.

[0055] The cables and / or the winches may be mounted to the blade prior to lifting the blade and hoisting it towards the hub i.e. they may be attached to the blade when the blade is still at ground level.

[0056] A cable 110 may be regarded as a tension element i.e. an element which may be used to transmit a tension force. The term cable may be interchangeable for any of wire, rope, chain, cord, line, strand and / or hawser. In some examples, the cables may be at least 20 meters long. The cables may be long enough such that, once they connect the blade and the hub together, they may be used to compensate and reduce relative movements between a blade e.g. positioned at least 5 or 6 meters away from the hub, and the hub.

[0057] Figure 4a schematically shows a blade 22 hoisted by a crane (not shown) and positioned in proximity to the hub 20. When hoisted by a crane, the wind turbine blade 22 may be subjected to winds which may cause it to move or oscillate, making the mounting process more challenging. During the installation of an offshore wind turbine, the crane, and therefore the blade, may also be subjected to oscillations caused by sea waves.

[0058] In some examples, the method may comprise attaching one or more cables 110 to the blade 22. In these examples, the one or more winches 120 may be mounted on the hub 20. In other examples, the method may comprise attaching one or more cables 110 to the hub 20 and mounting one or more winches 120 to the blade 22.

[0059] In the example shown in figure 4a, the cables 110 are attached to the blade 22 and the winches 120 are mounted on the hub 20, in particular to the pitch bearing 72. In this particular example, the cables 110 are fixed to additional actuators 130 mounted to the hub and attaching the cables 110 to the blade 22 comprises fixing the one or more cables 110 to additional actuators 130 mounted to the blade i.e. the additional actuators carrying the cables.

[0060] In the specific example of figure 4, the additional actuator is a linear actuator, and more specifically a linear motor.

[0061] The cables 110 may be attached at an inside of the blade 22 and the winches 120 may be mounted at an inside of the hub 20. In other examples, the cables 110 may be attached at an outside of the blade 22 and the winches 120 may be mounted at an outside of the hub.

[0062] As shown in the figure, the one or more cables 110 and winches 120 may be mounted to an inner area of the blade 22 and / or the hub 20. In other examples, schematically shown in figure 4a’, the one or more cables 110 and winches 120 may be mounted to an outer area of the blade 22 and / or the hub 20.

[0063] Figure 4a shows two cables 110, each of them fixed to a linear actuator 130. The figure also shows two winches 120 mounted on the blade. It should be appreciated that in other examples, three or more cables may be fixed to three or more additional actuators, and that three or more winches may be mounted on the hub.

[0064] In some examples, positioning the blade 22 in proximity to the hub 20 may comprise positioning the blade 22 above the hub 20. The blade 22 may be positioned such that the central axis of the blade root end is located at a vertical position which is higher than the central axis of the mounting area of the hub 20. The blade 22 may be positioned above the hub 20 such that the one or more cables 110 mounted to the blade 22 may hang or fall towards the hub 20.

[0065] Further, positioning the blade 22 in proximity to the hub 20 may comprise positioning the blade root at least 5 or 6 meters away from the mounting area of the hub 20.

[0066] The method further comprises, at step 308, connecting the cables 110 to the winches 120, i.e. connecting the blade 22 and the hub 20. Figure 4b shows the blade 22 and hub 20 of figure 4a after the cables and the winches have been connected to each other.

[0067] The cables 110 may comprise a fixed end mounted to the blade 22 or the hub 20 and a loose end configured to be fixed to the other of the blade 22 and the hub 20. The method may comprise catching or picking the cables 110 mounted to the blade 22 or the hub 20 from within the other of the blade 22 and the hub 20 to connect the cables to the winches.

[0068] In some examples, the cables 110 may be attached to the blade 22 and the method may comprise catching or picking the cables 110 from within the hub 20. In other examples, the cables 110 may be attached to the hub 20, and the method may comprise catching or picking the cables 110 from within the blade 22.

[0069] The method may further comprise fixing the loose end of the cables 110 to the other of the blade 22 and the hub 20 and connecting the cables to the winches i.e. connecting the blade 22 and the hub 20 with the cables 110 and winches 120.

[0070] In some examples, the fixed end of the cables 110 may be mounted to the blade 22 or the hub 20 through a retention system (not shown), and the loose end of the cables 110 may be fixed to the winches 120 mounted to the other of the blade 22 and the hub 20. In other examples, the fixed end of the cables 110 may be fixed to winches mounted to one of the blade 22 and the hub 20 and the loose end of the cables 110 may be mounted to the other of the blade 22 and the hub 20 through a retention system.

[0071] In some examples, further discussed with reference to figure 5a, the loose ends of the cables 110 may be connected to each other in a single connection point e.g. they may beconnected to a catch rope, and the plurality of cables 110 may be caught together through the connection point, enhancing the mounting process. An operator may use a tool e.g. a pick comprising a hook, to catch all the cables at once through the connection point.

[0072] As shown in the example of figure 4b, the cable 110 fixed to the linear actuator 130 may be fixed to a winch 120 mounted to the hub 20.

[0073] In some examples, the method may comprise mounting at least six winches 120 to one of the blade 22 and the hub 20, and connecting each winch 120 to a cable 110. This may allow controlling translations along three mutually perpendicular axes effectively and even allows control of the rotations about these axes to a certain extent, enhancing the synchronization of the blade motion with the motion of the hub. In some examples, the cables 110 and the winches 120 may connect the blade 22 and the hub 20 such that they substantially form a hexapod.

[0074] Figure 4c schematically shows that fixing the cable 110 to the winch 120 may comprise passing the cable 110 through a coupling system 135 mounted to the hub 20. The coupling system 135 may be an automated locking device.

[0075] The coupling system 135 may comprise a shape which is complementary to a shape of the linear actuator 130 e.g. complementary to an end of the linear actuator 130. The coupling system 135 may be configured to mechanically fix the linear actuator 130, such that when in further steps the blade 22 approaches the hub 20, the linear actuator 130 is guided to the coupling system 135. Once the linear actuator 130 reaches the coupling system 135, the linear actuator 130 may be locked or fixed to the coupling system 135, connecting the blade 22 and the hub 20 together. The linear actuator 130 may thus be configured to be fixed to both the blade 22 and the hub 20.

[0076] In some examples, after connecting the cables 110 and the winches 120 to the blade 22 and the hub 20, the method may comprise controlling the crane and moving the wind turbine blade 22 away from the hub 20. Tension may be put to the cables, preparing them to be pulled by the winches by ensuring that there is sufficient tension in the cables.

[0077] The method further comprises, at step 310, sensing movement of the blade relative to the hub and, at step 312, activating the winches and pulling the cables to synchronize a motion of the blade and the hub and to guide the blade towards the hub in a first direction. Blade movements may be restricted in one or more directions and the relative motion between the blade and the hub may be substantially reduced.

[0078] In some examples, sensing movement of the blade 22 relative to the hub 20 may comprise measuring movements and / or position of the blade 22 and the hub 20. Motioninformation may be obtained to control the tension of the cables 110 in order to reduce the relative motion between the blade and the hub.

[0079] In some examples, one or more sensors mounted on the blade 22 and / or the hub 20 may be used to measure movements and / or position of the blade 22 and the hub 20. In some examples, the sensors may include vibration sensors, acceleration sensors and / or global positioning system (GPS) sensors. In further examples, the sensors may be mounted at the crane hoisting the blade.

[0080] In other examples, movements of the blade 22 relative to the hub 20 may be sensed by the control system operating the winches. In these examples, once the cables 110 are connected to the winches 120, the winches 120 may be activated such that they pull the cables 110 producing an initial constant tension. As the blade root may be in motion relative to the hub, in order to keep the tension constant, length of the cables may be continuously adjusted to the movement of the blade. Motion of the blade may be measured by knowing the length of the one or more cables and the amount of cable that there is on the drum of the winch. Independent of this relative distance measurement, by reading the velocity of the winches while following the relative motion with constant tension, the relative speed can be measured. Accordingly, in these examples, the control system of the winches may measure the motion of the blade.

[0081] In some examples, the method may comprise measuring a distance and / or position between the blade 22 and the hub 20, activating each of the winches 120 according to the measured distance and / or position and / or speed, and pulling the cables 110 to synchronize a motion of the blade 22 and the hub 20 and to guide the blade 22 towards the hub 20. The winches may be operated by a motor. In some examples, the power supply for the winches may be placed on the blade installation tool i.e. the tool connecting the blade and the crane, or on the hub.

[0082] Each of the winches 120 may be activated differently to compensate for blade oscillation and to orient the blade 22 to a desired position such that the longitudinal axis of the blade 22 may be brought to a mounting position i.e. such that the blade may be aligned with the hub 20. The activation of each of the winches may also vary during time, continuously adapting to the movements of the blade. In the example shown in figures 4a - 4c, pulling the cables 110 may comprise pulling a cable 110 fixed to a linear actuator 130 mounted to the blade 22. In some examples, the linear actuators 130 may be linear motors. The linear actuators 130 may have a range of at least 2 meters, specifically at least 3 meters. The linear actuator 130 may be mounted at a longitudinal position of the blade which is at least 2 meters, and specifically at least three meters away from the root of the blade. This may providemaneuverability and may enhance the mounting process, facilitating the further steps wherein the blade is approached to the mounting area of the hub.

[0083] In some examples, the method may comprise pulling at least three cables 110 fixed to three linear actuators 130 mounted to the blade 22. In some examples, the method may comprise pulling at least six cables 110 fixed to six linear actuators 130 mounted to the blade.

[0084] In some examples, pulling the cables may comprise aligning the blade with the mounting area of the hub. Throughout the present disclosure, aligning the blade with a mounting area of the hub may be regarded as positioning the blade in a position such that the central axis of the blade root end is substantially collinear with the central axis of the mounting area of the hub. Once both elements are aligned, they may be moved closer to each other and the blade may be mechanically joined to the mounting area e.g. via the pitch bearing.

[0085] In some examples, once the blade is aligned with the hub, the method may comprise guiding the blade towards the hub in a first direction. In some examples, guiding the blade towards the hub in a first direction may comprise guiding the blade along a longitudinal direction of the blade.

[0086] Motion of the blade caused by external forces e.g. wind or sea waves may cause it to move towards the hub in an uncontrolled manner. In some examples, as further discussed with reference to figure 5e, the method may comprise controlling the crane and moving the wind turbine blade 22 away from the hub with the crane i.e. the crane may pull the blade away from the hub. The winches instead pull the blades towards the hub. Tension of the cables may be maintained at all phases of the orbits of the hub and the blade due to the crane. Control over the final approach of the blade to the hub can hereby be improved.

[0087] In some examples, the torque applied by the winches may be limited to a maximum threshold value. Force exerted by the winches may not exceed the maximum threshold and safety of the system may be ensured. In some examples, the method may comprise controlling the crane and moving the wind turbine blade 22 towards the hub 20 with the crane. The force exerted by the cables 110 and winches 120 may be reduced, and the crane may contribute to guiding the blade 22 towards the hub 20.

[0088] The method may further comprise subsequently connecting the hub 20 and the blade 22 with at least an additional actuator 130 and damping the blade at least in a second direction opposite to the first direction.

[0089] The method comprises, at step 314, the blade subsequently approaching the hub while using one or more additional actuators capable of pushing or pulling the blade away from the hub to control movement of the blade towards the hub.

[0090] The additional actuator may dampen the blade in a direction opposite to the direction in which the blade approaches the hub e.g. opposite to the pulling direction of the cables, reducing the risk of the blade and the hub colliding and being damaged.

[0091] The additional actuator 130 may be at least one of a crane, a linear actuator, an inflatable element or an outward biased pin or rod.

[0092] In some examples, the additional actuator 130 may be configured to dampen the blade in two opposing directions. In these examples, the additional actuator 130 may be a linear actuator e.g. a linear motor.

[0093] The method may comprise connecting the hub 20 and the blade 22 with an additional actuator 130 when the blade is 3 meters or less away from the hub, in particular 2 meters or less away from the hub. The method may allow to approach and further contact the blade to the hub in a controlled manner. Relative oscillation between the blade and the hub may be substantially reduced, and the blade may be brought in closeness of the hub in a reliable process. This may also prevent the blade from moving towards the hub and potentially impacting the hub in an uncontrolled manner.

[0094] Figure 4d shows a blade 22 and a hub 20 after they have been connected to each other with the additional actuator 130. The blade 22 and the mounting area of the hub 20 are substantially aligned.

[0095] As schematically shown in the figure, connecting the hub 20 and the blade 22 with an additional actuator 130 may comprise mechanically fixing the linear actuator 130 to a coupling system 135 mounted to the hub 20.

[0096] The method may further comprise activating the linear actuators 130 and pulling the blade 22 towards the hub 20 i.e. the linear actuators 130 may be activated for the blade 22 to approach the hub 20. In some examples, the power supply for the linear actuators 130 may be placed on the blade installation tool or may be installed in the hub. Further, the torque applied on the linear actuators 130 may be limited to a maximum threshold value to ensure safety of the system.

[0097] Figure 4e shows a blade 22 and a hub 20 after activation of the different linear actuators 130. Each of the linear actuators may have been activated differently to control blade movements and to compensate oscillations of the blade 22 e.g. caused by winds or sea waves. In some examples, at least two linear actuators 130 may be activated.

[0098] In some examples, the method may comprise measuring a distance and / or position between the blade 22 and the hub 20, activating the additional actuator 130 according to the measured distance and / or position, and bringing the blade 22 towards the hub 20.

[0099] In some examples, the method may comprise controlling the crane and moving the wind turbine blade towards the hub with the crane.

[0100] The blade 22 and / or the hub 20 may include alignment bushings and / or alignment pins which may establish contact before e.g. fasteners on the blade 22 may contact with holes on a bearing ring. Once the blade 22 makes contact with the hub 20, specifically the pitch bearing 72 on the hub 20, fasteners such as studs may be used to connect the blade to the hub, specifically a ring of the pitch bearing. In some examples, the additional actuators may guide the fasteners on the blade 22 into the holes on the bearing ring automatically by following a defined motion path.

[0101] The method may further comprise removing the one or more cables 110 from the blade 22 or the hub 20 and removing the one or more winches 120 from the blade 22 or the hub 20. The method may further comprise removing the one or more additional actuators 130 from the blade 22 and / or the hub 20.

[0102] Figures 5a - 5f schematically show steps of a method for mounting a wind turbine blade 22 to a hub 20 according to another example of the present disclosure. Figures 5a - 5d also show a system 100 for synchronizing a wind turbine blade 22 with a mounting area of a hub 20 according to another example of the present disclosure.

[0103] Figure 5a schematically shows a blade 22 hoisted by a crane (not shown) and positioned in proximity to the hub 20. The blade 22 is positioned above the hub 20.

[0104] In this example, connecting the cables 110 and winches 120 to the blade 22 and the hub 20 may comprise catching the cables 110 mounted to the blade 22 from within the hub 20. The cables 110 may comprise a fixed end previously mounted to the blade 22 and a loose end configured to be fixed to the hub 20.

[0105] In the example of figure 5a, a plurality of cables 110 are fixed to the blade 22 and are joined together at their loose end at a connection point 140. A catch rope 141 eventually comprising a weight 142 is fixed to the connection point 140. An operator within the hub 20 may use a tool e.g. a pick comprising a hook to catch the cables 110 mounted to the blade 22. In this example, as the loose end of the cables 110 may be connected to each other in a single connection point 140 e.g. a catch rope, the plurality of the cables 110 may be caught together through the connection point 140.

[0106] An operator within the hub 20 may catch the catch rope 141 using a tool and may fix the cables 110 to an inner side of the hub 20. The crane may be controlled and the blade 22 may be moved closer to the mounting area of the hub 20 e.g. the blade 22 may bedescended such that the longitudinal axis of the blade root may substantially align with the axis of the hub 20.

[0107] Figure 5b shows the blade 22 and hub 20 of figure 5a after they have been connected to each other. The cables 110 and the winches 120 (not shown in the figure) connect the blade 22 to the hub 20. The longitudinal axis of the blade root and the mounting area of the hub are not aligned.

[0108] The method 300 for mounting a wind turbine blade 22 may comprise connecting each of the one or more cables 110 to a pair of winches i.e. to set of two winches 120. Figures 5b and 5c show that each of the one or more cables 110 is connected to a set of two winches 120.

[0109] In some examples, the system 100 may comprise six winches 120 and three cables 110, and each cable 110 may be configured to be connected to a set of two winches 120. In these examples, the method may comprise connecting at least three cables 110 to at least three sets of two winches 120.

[0110] In some examples, the cables 110 may extend between a first end and a second end, and may comprise a middle section between the first end and the second end. The first and second end of the cables may be connected to a set of two winches 120 i.e. each end of a same cable 110 may be connected to a different winch 120. Further, a middle section of each of the cables may be fixed to the blade e.g. through a retention system 115.

[0111] In other examples, the first end of two different cables 110 may be fixed to a same retention system 115, and the second end of the two cables 110 may be fixed to two different winches 120.

[0112] In these examples, the system 100 may comprise six winches 120 and six cables 110, wherein two different cables 110 may be configured to be connected to a same retention system 115, substantially forming a single cable 110, and wherein each of the cables 110 may be connected to a different winch 120.

[0113] In the example shown in figures 5a - 5e, the winches 210 may be mounted to the hub 20. In this particular example, six winches 120 are mounted to the hub 20, each of them connected to a cable 110 mounted to a retention system 115. The winches 120 and the cables 110 are mounted to an inner side of the blade 22 and the hub 20. In other examples (not shown) the winches 120 and the cables 110 may be mounted to an outer side of the blade 22 and the hub 20 e.g. using brackets.

[0114] As illustrated in figure 5c, the disposition of the winches 120 and the cables 110 may substantially define a hexapod. Such disposition of the winches 120 and the cables 110may allow controlling and / or adjusting the position of the blade in all six degrees of freedom, however mainly the 3 translations.

[0115] In other examples not illustrated herein, the winches 120 may be mounted to the blade 22 and the cables 110 may be fixed to the hub 20.

[0116] The method further comprises, at step 312, activating the winches 120 and pulling the cables 110 to synchronize a motion of the bade 22 and the hub 20 and to guide the blade 22 towards the hub 20 in a first direction. Figure 5d schematically illustrates step 310.

[0117] The arrows in the cables 110 of figure 5d show the pulling force exerted by the winches 120. The blade 22 may be guided towards the hub 20. Different forces may be exerted to the different cables in order to synchronize the motion of the blade and the hub and slowly align the blade to a mounting position. Figure 5d shows that the blade 22 is substantially aligned with the hub 20.

[0118] The relative motion between the blade 22 and the hub 20 e.g. due to the wind may be substantially reduced, and the motion of the blade may be synchronized to the motion of the hub.

[0119] The winches 120 may be activated until the blade is 2 or 4 meters away from the hub. The final approach of the blade to the hub, i.e. the last 2 - 4 meters, is carried out using an additional actuator 130 configured to dampen the blade at least in a second direction opposite to the first direction.

[0120] The method further comprises, at step 314, the blade subsequently approaching the hub while using one or more additional actuators capable of pushing or pulling the blade away from the hub to control movement of the blade towards the hub. The method may comprise subsequently connecting the hub 20 and the blade 22 with at least an additional actuator 130 and dampening the blade 22 at least in a second direction opposite to the first direction.

[0121] An additional actuator 130 may thus be installed in the blade or in the hub. Figure 5e schematically shows that using one or more additional actuators capable of pushing or pulling the blade away from the hub may comprise controlling the crane in order to move the wind turbine blade 22 away from the hub i.e. the crane may be used to pull the blade away from the hub. In this example, the blade 22 is held by a blade holder 160, which is connected to the crane (not shown). If the blade is installed horizontally, the crane may pull the blade substantially sideways, moving the crane away from the hub. If the blade is installed under an angle to the horizon, the crane may pull the blade away from the hub substantially in the direction of the blade axis.

[0122] Throughout the present disclosure, when reference is made to the crane pulling on the blade, it should be understood that this refers to the “crane system” as a whole, i.e. the system including e.g. taglines, blade holder systems as well as the actual crane itself.

[0123] Figure 5f schematically shows three additional actuators 130 installed in the hub 20, in particular in the pitch bearing 72. In the example of figure 5e, the additional actuators 130 are inflatable elements. One or more additional actuators 130 may be used to reliably approach the blade 22 towards the hub 20 at a position at which suitable fasteners may be used for mounting the blade 22.

[0124] In some examples, connecting the hub 20 and the blade 22 may comprise inflating the inflatable element. The size of the inflatable elements may be adapted or controlled i.e. increased or reduced, taking into account the distance between the blade and the hub at a given moment in time e.g. using position sensors.

[0125] In other examples, schematically shown in figure 5g, the additional actuator 130 may comprise an outward biased pin or rod, which may be configured to be mounted on the blade or on the hub.

[0126] Figure 6 schematically shows a winch 120 mounted on a hub and one or more cables 110 attached on the blade 20 according to a further example of the present disclosure.

[0127] The example differs from the examples illustrated in figures 5a-5f in that the winch 120 may be connected to at least a pair of cables 110 i.e. a single winch 120 may be connected to two or more cables 120. This configuration of the one or more cables may allow to regulate the tensioning forces in an easier manner, as less control scheme may be needed to synchronize a motion of the blade and the hub.

[0128] In the example shown in figure 6, one single winch 120 is attached to three cables 110 attached to the blade 22. The cables 110 may comprise a fixed end previously attached to the blade 22 and a loose end configured to be connected to the winch 120. The loose end of the two or more cables 110 may be connected to each other at a connection point 140 e.g. through a knot. Accordingly, in this example connecting the cables 110 and the winches 120 may comprise connecting the connection point 140 of two or more cables 110 to a winch 110. In some examples, the connection point 140 may be attached to an additional cable which may then be attached to the winch 120. In other examples, the connection point 140 may be directly attached to the winch 120.

[0129] In some examples, the winch may be mounted on a base attached at an inside of the hub e.g. the mounting plate of the pitch system. In other examples, the winch 120 may be mounted on a tool 150 arranged within the hub and the winch 120 may be configured to movealong the tool 150. The position or orientation of the winch may be modified, and the direction of the force exerted by the winch may be adapted to adapt for the mounting of different blades.

[0130] In some examples, the tool 150 may comprise multiple tubes connected and supported to the hub from above and / or from below through couplings or connectors e.g. threaded ends or bayonets coupling or internally expanded couplings. In order to reorient or reposition a winch, tubes may be connected, removed or reposition like scaffolding. In further examples, the winch 120 may be mounted on a chain or a cable which may extend from a first part of the hub to a second part of the hub. In yet another example, telescopic tubes may be used to change the position of a winch.

[0131] Even though in this example, only a single winch is shown, it will be clear that the ability to reposition or reorient a winch may also be used in implementations relying on multiple winches.

[0132] This written description uses examples to disclose the teaching, including the preferred embodiments, and also to enable any person skilled in the art to practice the teaching, including making and using any devices or systems and performing any incorporated methods. The patentable scope is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. Aspects from the various embodiments described, as well as other known equivalents for each such aspects, can be mixed and matched by one of ordinary skill in the art to construct additional embodiments and techniques in accordance with principles of this application. If reference signs related to drawings are placed in parentheses in a claim, they are solely for attempting to increase the intelligibility of the claim, and shall not be construed as limiting the scope of the claim.

Claims

CLAIMS1. A method (300) for mounting a wind turbine blade (22) on a hub (20), the method comprising:mounting (302) one or more winches (120) on one of the blade (22) and the hub (20); attaching one or more cables (110) for the winches (120) on the other of the blade (22) and the hub (20);hoisting the wind turbine blade (22) with a crane and positioning the wind turbine blade (22) in proximity to the hub (20);connecting the cables (110) to the winches (120);sensing movement of the blade (22) relative to the hub (20);activating the winches (120) and pulling the cables (110) to synchronize a motion of the blade (22) and the hub (20) and to guide the blade (22) towards the hub (20) in a first direction; andthe blade (22) subsequently approaching the hub (20) while using one or more additional actuators (130) capable of pushing or pulling the blade (22) away from the hub (20) to control movement of the blade (22) towards the hub (20).

2. The method (300) of claim 1, wherein cables (110) are attached to the blade (22) and the winches (120) are mounted on the hub (20).

3. The method (300) of claim 2, wherein the cables (110) are attached at an inside of the blade (22) and the winches (120) are mounted at an inside of the hub (20).

4. The method (300) of claim 1, wherein the additional actuators (130) include linear actuators carrying the cables (110) for the winches (120) and wherein the linear actuators (130) are activated for the blade (22) to approach the hub (20).

5. The method (300) of claim 4, wherein the linear actuators (130) are linear motors.

6. The method (300) of claim 4 or 5, wherein the method comprises activating at least two linear actuators (130).

7. The method (300) of claim 1, wherein each of the winches (120) is connected to at least a pair of cables (110).

8. The method (300) of claim 1, wherein the additional actuators (130) comprise one or more inflatable elements mounted on the hub (20) or wherein the additional actuators (130) comprise an outward biased pin or rod on the hub or the blade.

9. The method (300) of any of claims 1 -8, wherein sensing movement of the blade (22) relative to the hub (20) comprises measuring movements and / or a position of the blade (22) and the hub (20).

10. The method (300) of any of claims 1 - 9, wherein the method further comprises controlling the crane and moving the wind turbine blade (22) towards the hub (20) with the crane.

11. The method (300) of any of claims 1 - 10, wherein the cables (110) are attached to the blade (22), and hoisting the wind turbine blade (22) with a crane and positioning the wind turbine blade (22) in proximity of the hub (20) comprises positioning the blade (22) above the hub (20) and the method comprising picking the cables (110) from within the hub (20) to connect the cables (110) to the winches (120).

12. A wind turbine blade (22) comprising one or more linear actuators (130) configured for pushing the blade (22) away from the hub (20), and one or more cables (110), and wherein the cables (110) are configured to be connected to winches (120) mounted on the hub (20).

13. The wind turbine blade (22) of claim 12, comprising at least two linear actuators (130) mounted on the blade (22), wherein the linear actuators (130) carry the cables (110).

14. The wind turbine blade (22) of claim 12, wherein each of the winches (120) is configured to be connected to at least a pair of cables (110).

15. A kit comprising:one or more winches (120) configured for being mounted on one of a wind turbine blade (22) or a wind turbine hub (20),one or more cables (110) configured to be connected to the winches (120), the cables (110) configured for being attached to the other of the blade (22) and the hub (20), and one or more linear actuators (130) for being removably mounted on the blade (22) and configured to carry the cables (110).

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