Patent Description:
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 a gearbox. This way, the generator produces electricity which can be supplied to the electrical grid.

In wind turbines with a gearbox, the gearbox usually increases the speed of the wind-driven rotor and therefore the required size of the generator may be reduced. In contrast, directly driven generators, operate at the same rotational speed as the rotor. These generators therefore generally have a much larger diameter than generators used in wind turbines having a gearbox for providing a similar amount of power than a wind turbine with a gearbox.

A direct drive wind turbine generator may have e.g. a diameter of <NUM> - <NUM> meters (<NUM> - <NUM> inches), a length of e.g. <NUM> - <NUM> meters (<NUM> - <NUM> inches) and may rotate at low speed, for example in the range of <NUM> to <NUM> rpm (revolutions per minute). Alternatively, generators may also be coupled to a gearbox which increases the rotational speed of the generator to for example between <NUM> to <NUM> rpm or even more.

A generator generally comprises a rotor, a stator and an air gap separating the rotor and the stator, for example radially. The stator may be an inner structure and the rotor may surround the stator. A generator may be a permanent magnet excited generator (PMG).

Permanent magnets (PM) are generally comprised in the rotor (although they could also be alternatively arranged in the stator structure), whereas winding elements (e.g. coils) are usually included in the stator (although they could alternatively be arranged in the rotor structure). An air gap separates the permanent magnets and the coils. Permanent magnet generators are generally deemed to be reliable and require less maintenance than other generator typologies. This is an important reason why permanent magnet generator are employed in offshore wind turbines, and particularly in direct drive offshore wind turbines.

In direct drive wind turbines, a frame is generally provided above the tower. A frame usually supports the hub and the generator, and transfers loads to the tower. A frame, or at least a portion of a frame, may be made of cast steel. A nacelle, which is a housing arranged on top of a wind turbine tower, may cover and protect at least a portion of the frame.

Once a generator for a direct drive wind turbine is assembled, i.e. the rotor and the stator have been assembled, it has to be joined to a wind turbine hub and to a frame. For example, the generator may be lifted and horizontally attached to the frame. Then, the hub may be attached to the generator, also horizontally.

Due to the size and the weight of the generator, appropriate tools for lifting it and moving it are required. In particular, the generator must be handled with care for avoiding deforming the stator and/or the rotor, and therefore deforming the air gap between them.

In order to minimize the risk of air gap collapse while handling the generator, the generator may be reinforced. For example, one or more reinforcements may be attached to the generator for conferring additional rigidity to it before joining it to the frame. Mounting the reinforcements to the generator and removing them once the generator has been joined to the frame and the hub is time consuming. Specific tools able to manipulate the reinforced generator may also be necessary. Examples of prior art are given in <CIT>, <CIT>, <CIT> and <CIT>.

In an aspect of the present disclosure, a method is provided. The method comprises providing a wind turbine hub, a main frame and a generator. The method further comprises vertically moving at least one of the wind turbine hub and the generator towards the other of the wind turbine hub and the generator; attaching the wind turbine hub and the generator to form a hub-generator assembly; turning the hub-generator assembly while gripping the wind turbine hub; and attaching the hub-generator assembly to the main frame.

According to this aspect, a hub and a generator are first attached, and then flipped via the hub. The hub-generator assembly may then be joined to a main frame. In this way, an air gap of the generator may be protected and may not collapse, as the generator is not manipulated directly. Performing the turning through the hub may enable to have a center of gravity of the hub-generator assembly in the hub, which may avoid deformations in the generator.

Reinforcing the generator may not be necessary, as it is the hub which is flipped.

In a further aspect of the invention, a tool according to claim <NUM> for manipulating a hub is provided. The tool comprises a hub manipulating assembly configured to grip a hub. The tool further comprises two lateral supports for supporting the hub manipulating assembly between them. The hub manipulating assembly is configured to displace along the lateral supports and rotate with respect to the lateral supports.

In a further aspect of the invention a method is provided. The method comprises gripping a hub, wherein a hub portion configured to be attached to a generator is pointing downwards; lifting the hub; lowering the hub over a generator; lifting the hub with the generator attached; and turning the hub with the generator attached.

Each example is provided by way of explanation of the invention, not as a limitation of the invention.

<FIG> illustrates a perspective view of one example of a wind turbine <NUM>. As shown, the wind turbine <NUM> includes a tower <NUM> extending from a support surface <NUM>, a nacelle <NUM> mounted on the tower <NUM>, and a rotor <NUM> coupled to the nacelle <NUM>. The rotor <NUM> includes a rotatable rotor hub <NUM> and at least one rotor blade <NUM> coupled to and extending outwardly from the rotor hub <NUM>. For example, in the illustrated example, the rotor <NUM> includes three rotor blades <NUM>. However, in an alternative embodiment, the rotor <NUM> may include more or less than three rotor blades <NUM>. Each rotor blade <NUM> may be spaced from the rotor hub <NUM> to facilitate rotating the rotor <NUM> to enable kinetic energy to be transferred from the wind into usable mechanical energy, and subsequently, electrical energy. For instance, the rotor hub <NUM> may be rotatably coupled to an electric generator <NUM> (<FIG>) to permit electrical energy to be produced.

The tower <NUM> may be fabricated from tubular steel to define a cavity (not shown in <FIG>) between a support surface <NUM> and the nacelle <NUM>. In an alternative embodiment, the tower <NUM> may be any suitable type of a tower having any suitable height.

In examples, the rotor blades <NUM> may have a length ranging from about <NUM> meters (m) to about <NUM>, <NUM> or more. Rotor blades <NUM> may have any suitable length that enables the wind turbine <NUM> to function as described herein. For example, non-limiting examples of blade lengths include <NUM> or less, <NUM>, <NUM>, <NUM>, <NUM> or a length that is greater than <NUM>. As wind strikes the rotor blades <NUM> from a wind direction, the rotor <NUM> is rotated about a rotor axis. As the rotor blades <NUM> are rotated and subjected to centrifugal forces, the rotor blades <NUM> are also subjected to various forces and moments. As such, the rotor blades <NUM> may deflect and/or rotate from a neutral, or non-deflected, position to a deflected position.

Moreover, a pitch angle of the rotor blades <NUM>, i.e., an angle that determines an orientation of the rotor blades <NUM> with respect to the wind direction, may be changed by a pitch system to control the load and power generated by the wind turbine <NUM> by adjusting an angular position of at least one rotor blade <NUM> relative to wind vectors. During operation of the wind turbine <NUM>, the pitch system may particularly change a pitch angle of the rotor blades <NUM> 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 <NUM>.

A blade pitch of each rotor blade <NUM> may be controlled individually by a wind turbine controller <NUM> or by a pitch control system.

Further as the wind direction changes, a yaw direction of the nacelle <NUM> may be rotated about a yaw axis to position the rotor blades <NUM> with respect to wind direction.

The wind turbine controller <NUM> may be centrally located within the nacelle <NUM>. However, in other examples, the wind turbine controller <NUM> may be located within any other component of the wind turbine <NUM> or at a location outside the wind turbine. Further, the controller <NUM> may be communicatively coupled to any number of components of the wind turbine <NUM> in order to control the operation of such components.

The wind turbine controller <NUM> may include one or more processor(s) and associated memory device(s) configured to perform a variety of computer-implemented functions (e.g., performing the methods, steps, calculations and the like and storing relevant data as disclosed herein). The wind turbine controller may perform various different functions, such as receiving, transmitting and/or executing wind turbine control signals and controlling the overall operation of the wind turbine. The wind turbine controller may be programmed to control the overall operation based on information received from sensors indicating e.g. loads, wind speed, wind direction, turbulence failure of a component and other.

As used herein, the term "processor" refers not only to integrated circuits referred to in the art as being included in a computer, but also refers to a controller, a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific integrated circuit, and other programmable circuits. The processor is also configured to compute advanced control algorithms and communicate to a variety of Ethernet or serial-based protocols (Modbus, OPC, CAN, etc.). Additionally, the memory device(s) may comprise memory element(s) including, but not limited to, computer readable medium (e.g., random access memory (RAM)), computer readable non-volatile medium (e.g., a flash memory), a floppy disk, a compact disc-read only memory (CD-ROM), a magneto-optical disk (MOD), a digital versatile disc (DVD) and/or other suitable memory elements. Such memory device(s) may be configured to store suitable computer-readable instructions that, when implemented by the processor(s), configure the controller to perform the various functions as described herein.

The wind turbine <NUM> of <FIG> may be placed in an offshore or onshore location. The wind turbine of <FIG> may be a direct-drive wind turbine.

<FIG> illustrates a simplified, internal cross-sectional view of the nacelle <NUM> and the rotor hub <NUM> of a direct-drive wind turbine <NUM> such as the one in <FIG>. Some elements of the wind turbine <NUM> have not been illustrated for the sake of clarity. As shown, the generator <NUM> may be coupled to the rotor hub <NUM> of the wind turbine <NUM> for generating electrical power from the rotational energy generated. Thus, rotation of the rotor hub <NUM> drives the generator <NUM>.

It should be appreciated that frame <NUM> and generator <NUM> may generally be supported by a support frame or bedplate <NUM> positioned atop the wind turbine tower <NUM>. The bedplate <NUM> may be a bottom portion or may be joined to a bottom flange of a frame <NUM>. The nacelle <NUM> is rotatably coupled to the tower <NUM>. The bedplate <NUM> may be rotatably coupled to a wind turbine tower <NUM>.

The direct-drive wind turbine <NUM> of <FIG> comprises a generator <NUM> mounted on a frame <NUM>. The generator <NUM> comprises a generator stator <NUM> and a generator rotor <NUM> configured to rotate about a rotation axis RA. The frame <NUM> has a rear portion <NUM> and a front or protruding portion <NUM>. The protruding portion <NUM> may be integrally formed with the rear portion <NUM> or may be separate from the rear portion <NUM>. If separate formed, fasteners <NUM> such as bolts may attach the front <NUM> and rear <NUM> portions of the frame <NUM>. The protruding portion <NUM> extends beyond the generator <NUM>. The rear portion <NUM> is provided between the front portion <NUM> and the tower <NUM>.

A rear portion <NUM> of the frame <NUM> may be called main frame <NUM>. A main frame may transfer the loads and the vibrations acting on the rotor <NUM> of a wind turbine <NUM> to the tower <NUM> of the wind turbine <NUM>. A main frame may be made of cast steel. A main frame may have a bottom opening, a front opening and a rear opening. The bottom opening may enable passage between the main frame and an inside of the tower <NUM>, the front opening may enable passage between the main frame and an inside <NUM> of the rotor hub <NUM>, e.g. through a front portion <NUM>, and the rear opening may enable passage between the main frame and an inside of the nacelle <NUM>.

In <FIG>, the protruding portion <NUM> extends towards the rotor hub <NUM> of the wind turbine <NUM> along the rotation axis RA. Thus, the protruding portion <NUM> may extend in an upwind direction along the rotation axis RA. At least a part of the protruding portion <NUM> may be placed in a room <NUM> defined inside the rotor hub <NUM>. The room <NUM> may be defined as the hollow body of the rotor hub <NUM>.

A protruding portion <NUM> of the frame <NUM> may be called main frame <NUM>. The main frame <NUM> may comprise a first structure and a second structure. The first and second structures are configured to rotate relative to each other and about the rotation axis RA. The first structure may be attached to the generator stator <NUM> and the second structure may be attached to the generator rotor <NUM>. The terms first are second are interchangeably herein.

In <FIG>, the first structure is an inner structure <NUM> and the second structure is an outer structure <NUM>. In another example, the first structure may be an outer structure and the second structure may be an inner structure. In both examples the inner and the outer structure may rotate relative to each other and about the rotation axis RA.

The outer structure <NUM> may be operatively connected to the rotor hub <NUM> through the generator rotor <NUM>. The latter may be achieved, for instance, through a series of bolts <NUM>. The bolts <NUM> may join together the rotor hub <NUM>, the outer structure <NUM> and the generator rotor <NUM> in such a way that at least a part of the generator rotor <NUM> is sandwiched by the rotor hub <NUM> and the outer structure <NUM>. This exemplary joint may allow to transmit the rotating movement of the rotor hub <NUM> to the outer structure <NUM> through the generator rotor <NUM>. Conversely, if for example the outer structure <NUM> is braked, then the generator rotor <NUM> and the rotor hub <NUM> may be braked as well. In another example, the joint may be achieved through any fasteners available on the market or even through welding.

The first structure, e.g. the inner structure <NUM>, may have a tapered region <NUM> towards the rotor hub <NUM>. The second structure, e.g. the outer structure <NUM>, may be rotatably mounted on the tapered region <NUM>. , the second structure can rotate about the rotation axis RA and the first structure. The tapered region <NUM> may protrude from the generator <NUM>, at least partially, towards the rotor hub <NUM>.

The direct-drive wind turbine <NUM> may further comprise a pair of bearings <NUM> between the second structure, e.g. the outer structure <NUM>, and the first structure, e.g. the inner structure <NUM>. The pair of bearings <NUM> may be spaced apart each other along the rotational axis RA. Alternatively, a single bearing may rotatably connect the first structure and the second structure.

In <FIG>, the generator rotor <NUM> rotatably surrounds the generator stator <NUM>. However, in other examples, the generator stator may surround the generator rotor.

One aspect of the present disclosure provides a method <NUM>. A schematic diagram of the method <NUM> is provided in <FIG>. An example of a possible implementation of method <NUM> is shown in <FIG>. This method <NUM> may be implemented by using a tool configured to perform the steps of the method <NUM>. An example of such a tool <NUM> can be seen e.g. in <FIG> and <FIG>.

The method comprises, at block <NUM>, providing a wind turbine hub <NUM>, a generator <NUM> and a main frame <NUM>. The method comprises, at block <NUM>, vertically moving at least one of the hub <NUM> and the generator <NUM> towards the other of the hub <NUM> and the generator <NUM>. The hub <NUM> and the generator <NUM> are brought closer such that a portion of the hub configured to be attached to the generator faces a portion of the generator configured to be attached to the hub. Any generator suitable for a direct drive wind turbine may be used. For example, an electrically excited generator may be used. In other examples, a permanent magnet excited generator may be used. In some examples, the generator may be a superconducting generator.

In some examples, the hub <NUM> may be lowered towards the generator <NUM>. This has been schematically represented in <FIG>. In <FIG>, a tool <NUM> is holding a hub <NUM> such that a portion of the hub configured to be joined to the generator is pointing downwards. The generator <NUM> is arranged below the hub <NUM> such that when the hub is lowered over the generator, the hub and the generator may be attached. The generator can be placed on a generator support <NUM>. In this example, the generator <NUM> remains still, it is not moved towards the hub <NUM>.

A tool <NUM> may comprise one or more sensors <NUM> (see for example <FIG>) configured to sense the generator <NUM>. For example, lasers and/or cameras may be provided in the tool, e.g. in a hub manipulating assembly <NUM> of the tool, such that a position of the hub <NUM> with respect to the generator may be known. A sensor suitable for measuring a distance between the hub <NUM> and the generator <NUM> may be used. One or more sensors, targets and/or marks may be provided in the generator <NUM> for use in conjunction with one or more sensors <NUM> in the tool <NUM>.

In some other examples, the generator <NUM> may be vertically moved towards the hub <NUM>, for instance by a vertically, e.g. upwards, movable platform. The generator <NUM> may be moved additionally or alternatively to moving the hub <NUM>. Since the generator is, due to its nature, less stiff than the hub, manipulations of the generator can lead to deformations. In <FIG> and <FIG>, the hub is kept still. This may help to avoid deformation of an air gap between the stator and the rotor.

In some examples, the generator <NUM> may be provided already mounted on, e.g. attached to, a front frame <NUM>. The front frame <NUM> is configured to be attached to the main frame <NUM>. For example, in <FIG>, the generator <NUM> is attached to a front frame <NUM>. Attaching the generator <NUM> and the front frame <NUM> may be performed before placing the generator <NUM> in a suitable position for joining it to the hub <NUM>, e.g. substantially below the hub <NUM>. A front frame <NUM> may comprise a portion configured to support the generator <NUM>, e.g. an inner structure <NUM>, and a portion configured to be attached to the wind turbine hub <NUM>, e.g. an outer structure <NUM>.

The method further comprises, at block <NUM>, attaching the hub <NUM> and the generator <NUM> to form a hub-generator assembly <NUM>. <FIG> illustrates this step. Fasteners such as bolts <NUM> may be used. In general, any suitable type of fastener may be used. If the generator is attached to a front frame <NUM>, the hub <NUM> may be attached to the portion configured to be attached to the wind turbine hub <NUM>, e.g. to an outer structure <NUM> as in the example of <FIG>.

Having the generator <NUM> on the ground or on a support <NUM> on the ground may facilitate the attachment of the hub and the generator. Also, manipulation of the generator <NUM> leading to an air gap collapse may be avoided.

The method further comprises, at block <NUM>, turning, while gripping the hub <NUM>, the hub-generator assembly <NUM>. <FIG> depicts an example of this. In <FIG>, the tool <NUM>, which grips the hub <NUM>, turns the hub-generator <NUM> assembly around an axis of rotation <NUM> (see also e.g. <FIG> and <FIG>). , the hub-generator assembly is flipped from a substantially vertical orientation to a substantially horizontal orientation.

As the axis of rotation <NUM> crosses the hub <NUM>, the forces and loads are concentrated in the hub. The axis of rotation <NUM> may lie close to the center of gravity of the hub-generator assembly <NUM>. The hub <NUM> and the tool <NUM> are thus used as a counterweight to reinforce the connection with the generator <NUM>. Therefore, contrary to when directly manipulating the generator, e.g. turning the generator by its outer surface, an air gap of the generator <NUM> may be protected from collapse or deformation. Also, adding reinforcements to the generator for avoiding its deformation may not be necessary.

Before turning the hub-generator assembly <NUM>, the hub-generator assembly may be lifted. Lifting enables having enough space for rotating the hub-generator assembly <NUM> without damaging it. Lifting also allows positioning the hub-generator assembly <NUM> at a suitable height (distance above the floor) for joining it to a main frame <NUM>. If a supporting structure <NUM> has been used for supporting the generator <NUM> (or the generator <NUM> and a front frame <NUM>), the structure <NUM> may be removed before the hub <NUM> is rotated. The hub-generator assembly <NUM> has been lifted in <FIG>, before rotating it in <FIG>.

The hub-generator assembly may be rotated between <NUM>º and <NUM>º (degrees), and specifically between <NUM>º and <NUM>º. For example, the hub-generator assembly may be rotated about <NUM>º, <NUM>º or <NUM>º. Such a rotation may facilitate orienting the hub-generator assembly <NUM> for joining it to a main frame <NUM>. The tool <NUM>, e.g. a hub manipulating assembly <NUM> of the tool <NUM>, may be reinforced <NUM> in a part which is to be below the hub-generator assembly <NUM> after the turning.

The method further comprises, at block <NUM>, attaching the hub-generator assembly <NUM> to the main frame <NUM>. A main frame <NUM> may be moved towards the hub-generator assembly <NUM>, for example in a substantially horizontal direction. If a generator <NUM> has not been provided already attached to a front frame <NUM>, the main frame <NUM> may be attached to the front frame <NUM> before attaching the hub-generator assembly to the main frame <NUM>. Attachment of the hub-generator assembly <NUM> to the main frame <NUM> may be by the front frame <NUM>. If the main frame <NUM> and the front frame <NUM> are provided as a single piece, moving the main frame <NUM> includes moving the front frame <NUM>. , frame <NUM> is moved. A portion of the frame <NUM>, e.g. a portion of the front frame <NUM>, configured to be attached to a hub-generator assembly <NUM> may be placed facing a portion of the hub-generator assembly <NUM> configured to be attached to the portion of the frame <NUM>, e.g. a portion of the front frame <NUM>. Sensors may be installed on the hub-generator assembly <NUM> and/or the frame <NUM> for helping in aligning them. Targets or marks may additionally or alternatively be placed on any of the hub-generator assembly and the frame.

If the hub-generator assembly <NUM> includes a front portion <NUM> of a frame <NUM>, the hub-generator assembly <NUM> may be in particular attached to a main frame <NUM>. For example, a front frame <NUM>, optionally an inner structure <NUM> (see <FIG>), may be attached to the main frame <NUM>. Any suitable fastener, including bolts <NUM>, may be used. For example, nuts and bolts may be used to join a rear flange of an inner structure <NUM> to a front flange of the main frame <NUM>.

As illustrated in <FIG>, a main frame <NUM> may be incorporated in a nacelle <NUM>, and the nacelle <NUM> with the main frame <NUM> may be moved towards the hub-generator assembly <NUM>. A movable platform <NUM> may horizontally move the nacelle <NUM>.

By performing method <NUM>, a hub <NUM>, a generator <NUM> and a main frame for a direct drive wind turbine <NUM> may be attached without damaging an air gap of the generator. By first joining the hub and the generator, and by then flipping the assembly while gripping the hub, the risk of damaging an air gap of the generator may be reduced. As a generator is not directly rotated (i.e. the generator is rotated, but via the hub), adding reinforcements to the generator may not be needed. Attachment of the pieces may be faster and more convenient than first manipulating the generator for attaching it to the frame, and then attaching the hub to the generator. Also, vertically joining the hub and the generator may be simpler and safer than horizontally joining them, as less tools and manipulation of the structures above the ground may be necessary in the first case.

Still with regard to method <NUM> and <FIG> and <FIG>, the hub <NUM> may be gripped before step <NUM>. For example, a tool <NUM> may grip and lift the hub <NUM> before moving, e.g. lowering, the hub <NUM> towards the generator <NUM>. Gripping may include lowering a hub manipulating assembly <NUM> of a tool <NUM> such that it surrounds the hub <NUM>. <FIG> illustrates that a hub <NUM> has been arranged below the tool. The hub <NUM> may be placed on a hub support <NUM>. The hub is placed such that a portion of the hub configured to be attached to a generator <NUM> points downwards. A hub may be placed such that when operating the tool for gripping the hub, e.g. lowering a hub manipulating assembly <NUM> of the tool <NUM>, engaging pins <NUM> for grabbing the hub are positioned between the hub openings for attaching wind turbine blades <NUM>.

Sensors <NUM> on the hub manipulating assembly <NUM> of the tool <NUM> may help to position the tool portion correctly with respect to the hub, e.g. around the hub. A hub manipulating assembly <NUM> may be moved vertically and horizontally for adjusting its position with respect to the hub. Lateral supports <NUM> of the tool may help to move the hub manipulating assembly <NUM> vertically and horizontally.

Gripping the hub <NUM> may include clamping the hub <NUM> at two points (at least) between hub openings for attaching wind turbine blades <NUM>. A hub <NUM> may be particularly reinforced in these regions, which may allow to rotate the hub-generator assembly <NUM> without deforming the hub <NUM>. Thus, clamping the hub in these regions may be particularly suitable for later on turning the hub-generator assembly <NUM> and protecting an air gap of the generator.

The hub manipulating assembly <NUM> of the tool <NUM> may comprise hub engaging pins <NUM>. The pins <NUM> may be moved towards the hub, and engage the hub, e.g. a hub surface between the openings for arranging the wind turbine blades <NUM> as in <FIG>. The engaging pins <NUM> may be configured to mate with receptacles on the hub. A male-female coupling may be formed.

A further aspect of the present disclosure provides a method <NUM>, schematically illustrated in <FIG>. The method may be performed by a tool <NUM> as described further below, e.g. with respect to <FIG>.

The method comprises, at block <NUM>, gripping a hub <NUM>, wherein a hub portion configured to be attached to a generator <NUM> is pointing downwards. A hub manipulating assembly <NUM> of the tool <NUM> may be lowered. A hub manipulating assembly <NUM> of a tool <NUM> may surround the hub <NUM>. The hub <NUM> may be clamped between hub openings for attaching wind turbine blades. Hub engaging ping <NUM> may be moved towards the hub <NUM> to this end. These aspects may be seen in <FIG> and <FIG>.

The method further comprises, at block <NUM>, lifting the hub. A generator <NUM>, either alone or attached to a front frame11, may be positioned substantially below the hub <NUM>.

The method further comprises, at blocks <NUM> and <NUM>, lowering the hub over a generator and attaching the generator <NUM> to the hub <NUM> (see <FIG> and <FIG>). Lowering the hub may comprise measuring a distance between a tool, e.g. the hub manipulating assembly <NUM>, and the hub.

The method further comprises, at block <NUM>, lifting the hub <NUM> with the generator <NUM> attached. A tool lifting the hub and the generator can be seen in <FIG>.

The method further comprises, at block <NUM>, turning the hub with the generator attached. Rotation may be between <NUM>º and <NUM>º. After the rotation, a main frame <NUM> and the generator <NUM> may be attached. A tool rotating a hub-generator assembly can be seen in figure 3F. If the generator is provided attached to a front frame <NUM>, the assembly hub-generator may be attached to the main frame <NUM> through the front frame <NUM>.

Aspects of method <NUM> can be combined with aspects of method <NUM>. Explanations provided with respect to method <NUM> apply also for method <NUM>, and vice versa.

A further aspect of the present disclosure provides a tool for manipulating a hub. The tool comprises two lateral supports and a hub manipulating assembly. The lateral supports are configured to support the hub manipulating assembly between them. The hub manipulating assembly is configured to grip a hub. The hub manipulating assembly is also configured to move along the lateral supports and rotate with respect to the lateral supports. This tool may be used to perform the methods <NUM> and <NUM> described above.

<FIG> illustrates a perspective view of an example of a tool <NUM>. The tool <NUM> comprises two lateral supports <NUM> and a hub manipulating assembly <NUM>. The hub manipulating assembly <NUM> may rotate around a rotation axis <NUM>. The hub manipulating assembly <NUM> may comprise a base <NUM> and two arms <NUM> attached to opposite sides of the base <NUM>. The arms <NUM> are movably connected to the lateral supports <NUM>. The direction along a length of the arms <NUM> defines the axis of rotation <NUM>. When parallel to the ground, the axis of rotation <NUM> defines a Y axis.

A hub manipulating assembly <NUM> may be moved parallel to the ground along a Y axis and along an X axis, see <FIG>. A hub manipulating assembly <NUM> may also be moved vertically, i.e. perpendicularly to the ground, along a Z axis. The X, Y and Z axes are perpendicular between them. A hub manipulating assembly <NUM> may also be rotated around any of the X, Y and Z axes. A lateral support <NUM> may enable to move the hub manipulating assembly in all these directions, as necessary. A lateral support <NUM> may also enable to rotate the hub manipulating assembly around the axis of rotation <NUM>.

<FIG> shows a perspective view of an example of a lateral support <NUM>. A lateral support <NUM> may comprise a hub manipulating assembly engaging element <NUM>. The element <NUM> is configured to engage and rotate the hub manipulating assembly <NUM>, for example the arms <NUM> of the hub manipulating assembly <NUM>. An actuator such as a motor may be incorporated to the lateral support <NUM> and connected to the hub manipulating assembly engaging element <NUM> for rotating element <NUM>, and thus hub manipulating assembly <NUM>, around the axis of rotation <NUM>, for example around the Y axis. Element <NUM> may be or may include a shaft.

The hub manipulating assembly engaging element <NUM> may be moved upwards and downwards along a Z axis. The lateral support <NUM> may comprise a vertical guiding system <NUM> to this end. A vertical guiding system <NUM> may vertically guide the element <NUM> configured to engage and rotate the hub manipulating assembly <NUM>. A vertical guiding system may comprise two vertical guides <NUM> along which the hub manipulating assembly engaging element <NUM> may be vertically displaced. The vertical guides <NUM> may be screws, for example worm screws. The vertical guides <NUM> may be separated along an X direction.

The hub manipulating assembly engaging element <NUM> may be supported by a support <NUM> for the hub manipulating assembly engaging element. This support <NUM> may be the one which may be vertically moved in a Z direction along guides <NUM>.

The lateral support <NUM> may comprise a frame <NUM> in which the vertical guiding system <NUM> is arranged. Frame <NUM> may for example support the vertical guides <NUM>. Besides or instead of vertical guides <NUM>, rails <NUM> may be provided. Frame <NUM> may support the rails <NUM>. A support <NUM> for the engaging element <NUM> for the hub manipulating assembly <NUM> may be vertically slid over the rails <NUM>.

A frame <NUM> may comprise vertical <NUM> and horizontal <NUM> beams, and for example have a rectangular shape. A height of a frame <NUM>, which may be a maximum height (length along Z axis) of a lateral support <NUM>, may be sufficient for vertically lifting and rotating a hub <NUM> attached to a generator <NUM> for a direct drive wind turbine. Such a height may be between <NUM> and <NUM> meters in some examples.

The frame <NUM> may comprise a cap <NUM>, the cap <NUM> being a top portion of the frame <NUM>. The cap <NUM> may include one or more actuators to move the hub manipulating assembly engaging element <NUM> up and down. For example, motors may rotate the vertical guides <NUM> for moving the support <NUM> of engaging element <NUM>, and thus the element <NUM> for engaging a hub manipulating assembly engaging <NUM>, vertically.

A support <NUM> for a hub manipulating assembly engaging element <NUM> may comprise one or more actuators, such as motors or hydraulic linear actuators, for moving the hub manipulating assembly engaging element <NUM> along a Y and an X axis.

In this way, a hub manipulating assembly <NUM> may be rotated and moved in any direction, and a hub <NUM> held by the hub manipulating assembly may be reliably approached and joined to a generator <NUM>.

A lateral support <NUM> may further comprise one or more reinforcement structures <NUM>. A reinforcement structure <NUM> may be attached to a frame <NUM> for increasing the stability and the robustness of the frame, and thus of the lateral support <NUM>. A reinforcement structure <NUM> may have a triangular shape and may comprise horizontal <NUM> and inclined <NUM> beams.

A width (length along an X direction, see <FIG>) of a lateral support <NUM> for a hub manipulating assembly <NUM> may be between <NUM> and <NUM> meters in some examples, e.g. between <NUM> and <NUM> meters). The two lateral supports <NUM> may be substantially equal in terms of the guiding system <NUM>, frame <NUM> and reinforcements <NUM>. A distance between the two lateral supports <NUM> (holding the hub manipulating assembly <NUM> along a Y direction, see <FIG>) may in some examples be between <NUM> and <NUM> meters, e.g. between <NUM> and <NUM> meters.

A perspective view of an example of a hub manipulating assembly <NUM> can be seen in <FIG> and <FIG>. A hub manipulating assembly <NUM> may have a base <NUM>. The base <NUM> may have an annular or a similar shape. The base may be formed by several substantially straight segments joined at their longitudinal ends. The hub manipulating assembly, and in particular the base, may be configured to surround a hub <NUM> for a direct drive wind turbine <NUM>.

The hub manipulating assembly <NUM> may comprise one or more hub engaging pins <NUM>. The pins <NUM> are configured to grab and support a wind turbine hub <NUM>. The pins <NUM> may clamp a hub <NUM>. The pins <NUM> may be configured to mate with receptacles on the hub. In <FIG>, <FIG> and <FIG>, three hub engaging pins <NUM> can be seen. The hub engaging pins <NUM> can be attached to the hub manipulating assembly base <NUM> by supports <NUM> for the hub engaging pins <NUM>. A support <NUM> for a hub engaging pin <NUM> may comprise one or more actuators for approaching <NUM> and distancing <NUM> the pin <NUM> to a hub <NUM>. A pin <NUM> may be hydraulically or electrically actuated in some examples.

<FIG> shows a top view of a tool <NUM> holding a hub <NUM>. In this figure, directions with respect to the hub manipulating assembly <NUM> can be seen. An axis of rotation <NUM> defines a first direction, the Y' direction. The Y' axis may overlap the Y axis. A second and a third directions perpendicular to the Y' direction are the X' and Z' directions. In <FIG>, the X' axis and the Z' axis overlap with the X and Z axes, respectively. However, this will not be the case when the hub manipulating assembly <NUM> is rotated, as the X' and Z' axes will rotate around the Y' axis.

The axis of rotation or Y' axis divides the hub manipulating assembly in two portions: a first portion <NUM> and a second portion <NUM>. When the hub manipulating assembly <NUM> is supporting a hub <NUM> and a generator <NUM> for attaching them to a main frame <NUM> in a substantially horizontal direction (e.g. the Z' axis in <FIG> is parallel to the X axis in <FIG>), the second portion <NUM> may mainly be carrying the weight of the hub and the generator. Because of this, a first portion <NUM> may be called an upper portion, and a second portion <NUM> may be called a lower portion.

The hub manipulating assembly <NUM> may further comprise a reinforcement bar <NUM> between two consecutive engaging pins <NUM>, see <FIG> and <FIG>. The reinforcement bar <NUM> may be provided for helping in supporting the hub <NUM> and the generator <NUM>. The reinforcement bar <NUM> may be provided in a second (lower) portion <NUM> of the hub manipulating assembly <NUM>.

A support <NUM> of the pins <NUM> may extend in a Z' direction, and in particular in a +Z' direction (direction pointing to the reader in <FIG>). When a hub <NUM>, or a hub <NUM> attached to a generator <NUM>, is lifted or lowered, having the engaging pins <NUM> above the base <NUM> may direct the forces exerted on them by the hub towards the base <NUM>, and thus may help to carry and stabilize the loads.

An engaging pin <NUM> may comprise a ball joint <NUM>, see <FIG> and <FIG>. In particular, each engaging pin <NUM> may comprise a ball joint <NUM>. A ball joint <NUM> may help to improve the contact between the engaging pins <NUM> and the hub <NUM>. A ball joint <NUM> may also help to absorb the loads exerted on the engaging pins <NUM>, for example when rotating the hub and the generator.

The tool <NUM> may comprise one or more sensors <NUM> configured to sense a generator <NUM> and/or a hub <NUM>. For example, an engaging pin <NUM>, and in particular each engaging pin <NUM>, may comprise one or more sensors <NUM>. Sensors <NUM> may be comprised in supports for the engaging pins. One or more sensors <NUM> may be used when lowering the hub manipulating assembly <NUM> for grabbing the hub <NUM>. Sensors <NUM> may help to position the hub manipulating assembly <NUM> and the engaging pins <NUM> accurately around the hub <NUM>. Sensors may comprise cameras and/or lasers.

One or more sensors <NUM> may be also provided in the hub manipulating assembly <NUM> for helping to place the hub manipulating assembly <NUM> in a desired position. For example, lasers and/or cameras may be provided in the hub manipulating assembly base <NUM> such that a position of the hub with respect to the generator may be known. The sensors may sense the generator. These sensors <NUM> may also help to attach the hub manipulating assembly pins <NUM> to the hub <NUM> correctly. A sensor suitable for measuring a distance may be used.

The pins <NUM> may be substantially equally spaced around the hub manipulating assembly <NUM>. For example, if three engaging pins are present, two consecutive pins may be separated about <NUM> degrees around the base <NUM>. The pins <NUM> may be configured to grab the hub <NUM> between the hub openings for attaching the wind turbine blades <NUM>. The region of the hub between these openings may provide sufficient robustness and stiffness for supporting or the forces and loads when rotating the hub and the generator without suffering deformations.

Two pins <NUM> may be arranged in the second portion <NUM> of the hub manipulating assembly. The two pins <NUM> may be below the hub <NUM> and the generator <NUM> when rotating a hub-generator assembly and positioning for attaching the set to a main frame <NUM>, therefore support and stabilization of the hub-generator assembly may be enhanced. The two pins <NUM> in the second portion <NUM> may be particularly configured to support compression loads during rotation of the hub-generator assembly.

One pin <NUM> may be arranged in the first portion <NUM> of the hub manipulating assembly. This pin may be configured to hold the hub <NUM> during rotation of the hub-generator assembly <NUM> and to compensate for possible deflections of the assembly during the rotation.

Claim 1:
A method (<NUM>) comprising:
providing (<NUM>) a wind turbine hub (<NUM>), a main frame (<NUM>), and a generator (<NUM>);
vertically moving (<NUM>) at least one of the wind turbine hub (<NUM>) and the generator (<NUM>) towards the other of the wind turbine hub (<NUM>) and the generator (<NUM>);
attaching (<NUM>) the wind turbine hub (<NUM>) and the generator (<NUM>) to form a hub-generator assembly (<NUM>);
turning (<NUM>) the hub-generator assembly (<NUM>) while gripping the wind turbine hub (<NUM>); and
attaching (<NUM>) the hub-generator assembly (<NUM>) to the main frame (<NUM>).