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 winddriven rotor and therefore the required size of the generator may be reduced. In contrast, directly driven generators, for example used in offshore direct-drive wind turbines, operate at the same rotational speed as the rotor. They 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 rotor shaft may be rotatably mounted on a bedplate above the tower using one or more rotor shaft bearings arranged on the bedplate. In a direct-drive wind turbine, a bedplate may be a bottom of a frame or may be coupled to a bottom flange of a frame. The frame may cover the components arranged on the bedplate and may transfer loads to the tower. A frame may be made of cast steel. Yaw motors and electric cabinets may be on the bedplate and may be covered by the frame.

A nacelle, which is a housing arranged on top of a wind turbine tower, may cover and protect at least the components on the bedplate. In a direct-drive wind turbine the nacelle may cover at least the frame.

In direct-drive wind turbines, temporary supporting structures may be placed inside a frame to access different parts of the wind turbine, for example the rotor hub, the generator and the nacelle. Access to one or more of these parts may be needed during assembly and/or installation of the wind turbine. Access may also be required for maintenance operations.

Mounting supporting structures inside the frame each time they are needed may be time consuming and may delay accessing the required place or component. This may particularly apply when different supporting structures, for example structures of different heights or shapes, are required for different tasks in different places.

Document <CIT> discloses a nacelle of a wind turbine which includes a platform. The platform serves for a person, in particular service personnel, to be able to gain entry to the nacelle and work there. Control cabinets can for example be arranged on the platform. The platform can contribute to increase the stability and in particular stiffness of the nacelle.

In an aspect of the present disclosure, a foldable supporting structure for a central frame of a direct-drive wind turbine is provided. The supporting structure is configured to assume a deployed configuration and a stowed configuration. In the stowed configuration, the supporting structure is folded and has a shape and size such that the supporting structure can be introduced into the central frame from and outside. In the deployed configuration, the supporting structure is unfolded has a one or more increased dimensions with respect to the stowed configuration, and comprises a working platform.

According to this aspect, the dimensions of a supporting structure may be reduced to easily introduce it into the central frame. For example, a supporting structure may be folded for reducing the space that it occupies. Once inside the central frame, it may be deployed, e.g. by unfolding it.

Folding may also facilitate to introduce an assembled supporting structure (or at least assembled in part) in the central frame, instead of bringing and installing components one by one. Assembly and installation time of the central frame may be reduced. The supporting structure may be assembled, at least partially, outside the main production line. Efficiency in the main line may be therefore improved.

Furthermore, folding may enable to incorporate more than one functionality into the supporting structure or to access different places or components in the central frame once the supporting structure is deployed. Maintenance time in the central frame or places where access is needed from the central frame may therefore be reduced. Temporary platforms may be avoided.

Additional components or parts of the supporting structure may be placed inside the central frame after the first and second sides have been unfolded in the central frame.

Throughout this disclosure, a central frame may be understood as a structural component of a direct-drive wind turbine configured to transfer loads and vibrations acting on the rotor of the wind turbine to the tower of the wind turbine. A central frame may be also known as base frame, main frame or rear frame. A bottom of the central frame may be connected to the tower of the wind turbine. The electrical generator may be connected to a front side of the central frame, or to a front frame attached at a front side of the central frame.

In a further aspect, a method for handling a supporting structure for use in a central frame of a direct-drive wind turbine is provided. The method comprises lifting and introducing the supporting structure into the central frame while the supporting structure is in a stowed configuration. The method further comprises attaching the supporting structure to the central frame and deploying the supporting structure.

In yet a further aspect, a supporting structure for a central frame of a direct-drive wind turbine is provided. The supporting structure comprises a first side comprising a first lateral platform, a second opposite side comprising a second lateral platform, and a central portion comprising a central platform. The first and second lateral platforms are above the central platform and are configured to be rotated and slid with respect to the central platform.

Each example is provided by way of explanation of the invention, not as a limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention as defined in the claims.

<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 computerreadable 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 protruding portion <NUM> extending beyond the generator <NUM>.

As shown in <FIG>, the first structure may have a tapered region <NUM> towards the rotor hub <NUM>. The tapered region <NUM> may protrude from the generator <NUM> at least partially, towards the rotor hub <NUM>. The generator rotor <NUM> may be rotatably mounted on the generator stator <NUM>.

In the example illustrated 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.

In another example, the protruding portion may extend away from the rotor hub <NUM> of the wind turbine <NUM> along the rotation axis RA. The protruding portion <NUM> may extend towards the bedplate <NUM> or tower <NUM>, i.e. the protruding portion <NUM> may be positioned in an opposite direction to the rotor hub <NUM> along the rotation axis RA. Therefore, the protruding portion <NUM> may extend in a downwind direction along the rotation axis RA.

Following with the example of <FIG>, 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>.

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

The protruding portion <NUM> may be a front portion of the frame <NUM>. The protruding portion <NUM> may be integrally formed with the frame <NUM> or may be separate from the frame <NUM>. The frame <NUM> may have a rear portion <NUM> facing the bedplate <NUM> of the wind turbine <NUM> and/or the front portion of the frame <NUM>.

A frame <NUM> without the protrusion <NUM> may be called central frame. A central frame <NUM> 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 central frame <NUM> may be made of cast steel. An example of a central frame <NUM> or of a portion of a central frame may be seen in <FIG> and <FIG>. A central frame <NUM> may have a bottom opening <NUM>, a front opening <NUM> and a rear opening <NUM>, see e.g. <FIG>. The bottom opening <NUM> may enable passage between the central frame <NUM> and an inside of the tower <NUM>, the front opening <NUM> may enable passage between the central frame <NUM> and an inside <NUM> of the rotor hub <NUM> or a front frame, and the rear opening <NUM> may enable passage between the central frame <NUM> and an inside of the nacelle <NUM>.

One aspect of the present disclosure provides a foldable supporting structure <NUM> for a central frame <NUM> of a direct-drive wind turbine <NUM>. The supporting structure <NUM> is configured to assume a deployed configuration and a stowed configuration. In the stowed configuration, the supporting structure <NUM> is folded and has a shape and size such that the supporting structure can be introduced into the central frame <NUM> from an outside. In the deployed configuration, the supporting structure is unfolded and has one or more increased dimensions with respect to the stowed configuration, and comprises a working platform. A working platform may be understood as a support where operators may stand on and move on.

One or more dimensions of the supporting structure <NUM> may be larger in the deployed state than in the stowed state. A length and/or a height and/or a width of the supporting structure <NUM> may be increased with respect to the stowed configuration. For example, a length may be larger in the deployed state of the supporting structure <NUM> than in the stowed state of the supporting structure <NUM>.

A supporting structure <NUM> may comprise a central portion <NUM> and one or more side portions <NUM>, <NUM> hingedly mounted with respect to the central portion <NUM>. A first <NUM> and second <NUM> side portions may be configured to be folded towards the central portion <NUM>.

The supporting structure <NUM> may further comprise one or more parts configured to move with respect to, e.g. towards, the central portion <NUM> from a first position to a second position. One or more parts configured to move may be slidably arranged with respect to the central portion <NUM>. Such parts may be referred to as slidable parts <NUM>. This may help to reduce the dimensions of the supporting structure for introducing it in the central frame as well.

A first example of a supporting structure <NUM> is shown in <FIG>. The first side portion <NUM> and the second opposite side portion <NUM> are unfolded in <FIG> and folded in <FIG>. The supporting structure <NUM> is in a deployed configuration in <FIG>, and is in a stowed configuration in <FIG>. Hinges <NUM> or any suitable rotatable joint between the central portion <NUM> and the first <NUM> or second <NUM> side portions may enable folding the first and second side portions towards the central portion <NUM>.

Folding the supporting structure <NUM> may help to introduce the structure <NUM> inside a central frame <NUM>, as illustrated in <FIG>. The folded supporting structure <NUM> may be lifted and entered in the central frame <NUM>, for example through a rear opening <NUM> of the central frame <NUM>. The rear opening <NUM> may be configured to be downwind.

The central portion <NUM> may comprise a first plurality of beams <NUM> and a second plurality of beams <NUM>. The second plurality of beams <NUM> may be substantially perpendicular to the first plurality of beams <NUM>. The first plurality of beams <NUM> may comprise two substantially parallel beams, and the second plurality of beams <NUM> may comprise two or more beams placed between the two substantially parallel beams and attached to the two substantially parallel beams by its ends. Attachment may be mechanical, e.g. through nuts and bolts or rivets. The first <NUM> and second <NUM> plurality of beams may form a base framework.

The central portion <NUM> may comprise a plurality of brackets <NUM>. Brackets <NUM> may extend downwards (configured to extend towards an inside of the tower <NUM>) and may include one or more hooks or hangers <NUM>. A basket <NUM> may be supported by one bracket or by two or more brackets. Baskets may be used to support cables or any other suitable component.

The central portion <NUM> may further comprise one or more plates <NUM> attached, e.g. mechanically, to beams of the first <NUM> and second <NUM> plurality of beams. Operators may stand on one or more plates <NUM> and move around. Plates <NUM> may be substantially flat.

The first side portion <NUM> may comprise a plurality of beams <NUM>. Beams <NUM> may be substantially parallel to each other and may be rotatably attached to the central portion <NUM>. An end of a beam <NUM> may be directly or indirectly connected via a hinge <NUM> or any other suitable rotatable connector to a beam of the first plurality of beams <NUM>. The cantilevered beams <NUM> of the first side portion <NUM> of the supporting structure <NUM> may be substantially parallel to the second plurality of beams <NUM> of the central portion <NUM> when the first side portion <NUM> is in an unfolded state as in <FIG>.

One or more brackets <NUM> may also extend downwards (in an unfolded position of the first side portion <NUM>) from one or more beams <NUM>, for example a central beam of the first side <NUM>. One or more baskets <NUM> may be attached to one or more brackets <NUM>. For example, a beam <NUM> may comprise two or more brackets <NUM> pointing downwards and a basket <NUM> may be attached to two or more of the brackets <NUM> of beam <NUM>.

The first side portion <NUM> may further comprise one or more plates <NUM>, each plate attached to two or more beams <NUM>.

The features of the first side portion <NUM> may likewise be found in the second opposite side portion <NUM>, as shown in <FIG>.

In some examples, one of the one or more slidable parts <NUM> may be a column <NUM> configured to guide at least a cable from the central frame <NUM> down a wind turbine tower <NUM> in the deployed configuration. Such one or more cables may be configured to carry power generated by the generator <NUM> towards the electrical grid. A column <NUM> may be formed by four vertical beams <NUM> joined by horizontal struts <NUM>, as for example as illustrated in <FIG>. Inclined struts <NUM> may be used to reinforce the column <NUM>.

A column <NUM> may be comprised in the central portion <NUM> of the structure. When the supporting structure <NUM> is outside the central frame <NUM>, the column <NUM> may protrude upwards. This position may be a folded position for the column <NUM>. Once the structure <NUM> is inside the central fame and it is unfolded, the column <NUM> may be slid downwards, as depicted in <FIG>. This may be an unfolded position for the column <NUM>. Once unfolded, the supporting structure <NUM> may be attached to an inside flange <NUM> of a bottom of the central frame <NUM>.

The supporting structure <NUM> may be made of one or more metals, such as steel.

After attaching the supporting structure <NUM> to a bottom of the central frame <NUM>, further components may be added. For example, as shown in <FIG>, a ladder <NUM> configured to extend into a wind turbine tower <NUM> and/or a ladder <NUM> configured to access the nacelle <NUM> may be added. Ladder <NUM> may be foldable. Ladder <NUM> may have a horizontal support <NUM> at its top. A door <NUM> to regulate access through the front opening <NUM> may also be included. Plates <NUM> may be added to one or more of the central portion <NUM> and the first <NUM> and second <NUM> side portions in order to create a floor <NUM>. Floor <NUM> may be a bedplate <NUM> on which electrical cabinets and other equipment may be placed. Floor may be a working platform.

A second example of a supporting structure <NUM> is shown in <FIG>. Supporting structure <NUM> is unfolded in <FIG> and folded in <FIG>.

The central portion <NUM> may comprise a central platform <NUM>, the first side portion <NUM> may comprise a first lateral platform <NUM> and the second side portion <NUM> may comprise a second lateral platform <NUM>. In the deployed configuration, the first <NUM> and second <NUM> lateral platforms may be arranged at a different vertical level than, e.g. above, the central platform <NUM>. A platform may be formed by a frame comprising plate supports <NUM> such as beams and one or more plates <NUM> on the plate supports <NUM>. Attachment between a plate <NUM> and a frame may be mechanical, e.g. by nuts and bolts. In some examples, plates and plate supports may be integrally formed. Plates <NUM> may be made of one or more plastics.

The central platform <NUM> may be rectangular. The side platforms <NUM>, <NUM> may resemble a rectangle or a square except for an outside edge <NUM>, <NUM> which may be configured to adapt to an inside surface of the central frame <NUM>. An outside edge may include a protrusion or a flange which adapts to an inside surface of the central frame. Such an edge or flange may for example be rounded.

A joining element <NUM> may connect a lateral platform <NUM>, <NUM> to the central platform <NUM>. Two or more vertical beams, one or more vertical plates or any other suitable element may be used. The joining element <NUM> may support a lateral platform <NUM>, <NUM> over the central platform <NUM>.

The lateral platforms <NUM>, <NUM> may be accessible from the central platform <NUM>. The joining element <NUM> may comprise rungs <NUM>. In some examples, a joining element <NUM> may be stairs, which may facilitate passage between the central platform <NUM> and a lateral platform <NUM>, <NUM>. Stairs <NUM> may be formed by two vertical beams or bars and one or more horizontal rungs between the two vertical beams or bars <NUM>.

An inside edge or portion <NUM>, <NUM> of a lateral platform <NUM>, <NUM> may be vertically above an outside edge or portion <NUM> of the central platform <NUM> such that the supporting structure <NUM> has a U- or hat- shape in cross-section (in a cross-section including the joining elements <NUM>) in an unfolded position, as in <FIG>.

The lateral platforms <NUM>, <NUM> may be configured to rotate and to slide with respect, e.g. towards, the central platform <NUM>. A lateral edge <NUM> of a lateral platform <NUM>, <NUM> may have an elongated opening <NUM> which may engage a first rotational element <NUM> such as a rod or bar at a top of a joining element <NUM>. A beam <NUM> of the lateral platform <NUM>, <NUM> substantially parallel to the lateral edge <NUM> may also have an elongated opening <NUM> which may engage a second rotational element such as a rod or bar at a top of the joining element <NUM>. Beam <NUM> may be an opposite lateral edge. The first and second rotational elements may be the same, e.g. each opening <NUM> may engage with opposite ends of a single rotational element, or may be separate, e.g. two rotational elements.

A lateral platform <NUM>, <NUM> may be slid and then it may be rotated about a rotational axis <NUM> to make the supporting structure <NUM> more compact. The supporting structure <NUM> may then pass from a deployed configuration to a stowed configuration. For example, an inside end <NUM> of the opening <NUM> may engage with a rotating element <NUM> when the supporting structure is unfolded, a lateral platform <NUM>, <NUM> may be rotated and the lateral platform may be slid towards the central platform <NUM> until an outside end <NUM> of the opening <NUM> engages the rod and the lateral platform cannot continue sliding.

In other examples, a lateral platform <NUM>, <NUM> may first be rotated about a rotational axis <NUM> and then slid.

A lateral platform <NUM>, <NUM> may be longer in a direction substantially parallel to an axis of rotation <NUM> of the lateral platform than in a central platform <NUM> in the same direction. The dimensions of the lateral <NUM>, <NUM> and central <NUM> platforms may be selected according to the places where access is desired from them. The same applies to the distance, e.g. a vertical distance, between the lateral platforms <NUM>, <NUM> and the central platform <NUM>.

A supporting structure <NUM> may then be easily lifted into a central frame <NUM>. Lifting may be through a rear opening <NUM> of the central frame <NUM>. Once inside the central frame <NUM>, the supporting structure <NUM> may be unfolded, lowered and attached to the central frame <NUM>, as depicted in <FIG>. One or more supporting elements <NUM>, e.g. one or more vertical beams or legs, may be attached to a bottom of the central frame <NUM> in order to support the platforms <NUM>, <NUM>, <NUM> when lowered. A supporting element <NUM> may be attached to an inside flange of a bottom of the central frame <NUM> or it may be attached to a bedplate <NUM>.

A lateral platform <NUM>, <NUM> may be attached, e.g. bolted, to an inside lateral surface of a central frame <NUM> at least by an outside edge <NUM>, <NUM>. One or more connection points <NUM> may also be used to join a platform <NUM>, <NUM>, <NUM> to an inside surface of the central frame <NUM>. A connection point may be a corner joint or any suitable piece which allows to connect a platform to an inside surface of the central frame <NUM>. In some examples, a platform may be directly attached to the central frame, e.g. mechanically.

Other connection points <NUM> such as beams shorter than legs <NUM> may be used to attach an edge of the central platform <NUM> to a bottom portion of a front flange <NUM> of the central frame <NUM>, see e.g. <FIG>.

Once fixed to the central frame <NUM>, additional elements may be added to the supporting structure <NUM>, for example as shown in <FIG> and <FIG>.

By mounting a basic supporting structure outside the main line of production before lifting it inside the central frame <NUM>, assembly time in the main line of production may be reduced. Once the supporting structure <NUM> has been attached to an inside of the central frame <NUM>, further components may be added as required.

A ladder <NUM> may be attached to the central platform <NUM>, e.g. to an edge of the central platform <NUM> configured to be facing a rear opening <NUM> of the central frame <NUM>. One or more operators may then use the ladder <NUM> to access the central platform <NUM> from an inside of the central frame <NUM>. An operator may need to open a door <NUM> to access the central platform <NUM> from an inside of the central frame <NUM>. The central platform <NUM> may give access to the rotor hub <NUM>.

A door <NUM> may be attached to an inside edge <NUM>, <NUM> of a lateral platform <NUM>, <NUM>. Once an operator is on the central platform <NUM>, the operator may open the door <NUM> and access a lateral platform <NUM>, <NUM>. Lifting points <NUM> of the central frame <NUM> or the nacelle <NUM> may be accessed from the lateral platforms <NUM>, <NUM>.

In some examples (not shown), a ladder or another suitable element may enable accessing a lateral platform <NUM>, <NUM> without having to go on the central platform <NUM>.

Railings <NUM> may also be attached to one or more edges of a platform <NUM>, <NUM>, <NUM> for increasing the security of the people on a platform. A railing <NUM> may have one or more connection points <NUM> for attaching the railing <NUM> to an inside surface of the central frame <NUM>, for example a lateral inside surface and/or a top inside surface. As before, a connection point may be a corner joint or any suitable piece which allows to connect a railing <NUM> to an inside surface of the central frame <NUM>. In some examples, a railing may be directly attached to the central frame, e.g. through nuts and bolts.

A platform extension <NUM> may be mounted to an edge of the central platform <NUM> configured to be facing the rotor hub <NUM>, as depicted in <FIG> and <FIG>.

The supporting structure <NUM> may comprise two or more deployed configurations. A first configuration may be for accessing a part of the central frame <NUM>, and a second different configuration may be for accessing a second different part of the central frame <NUM>. For example, a first configuration may enable accessing a lower portion of a front flange <NUM> of the central frame and the lifting points <NUM> of the central frame or nacelle, see e.g. <FIG>. A second configuration may enable accessing an upper portion of a front flange <NUM> of the central frame <NUM>, see e.g. <FIG>.

The supporting structure <NUM> may also include one or more platform parts <NUM>, as in <FIG>. The one or more platform parts <NUM> are configured to form an additional platform <NUM>, for example above and between the lateral platforms <NUM>, <NUM>, as in <FIG>. A platform part <NUM> may be a platform plate <NUM>. A platform part <NUM> may be a supporting element <NUM> for one or more platform plates <NUM>. A supporting element <NUM> may be a rod or beam, such as in <FIG>, but other supporting elements may be used. In some other examples, a platform part may already be a single piece ready to mount and use as platform.

One or more platform parts <NUM> may be hanged on the railings <NUM>, for example above the central platform <NUM> as illustrated in <FIG>.

<FIG> shows a supporting structure <NUM> with an additional platform <NUM> assembled. The additional platform <NUM> may be accessible from the lateral platforms <NUM>, <NUM> and can be used to cross between them. The additional platform <NUM> may enable accessing an upper portion of a front flange <NUM> of the central frame <NUM>.

The additional platform <NUM> may be mounted on horizontal railings <NUM> above the elements <NUM> joining the lateral platforms <NUM>, <NUM> to the central platform <NUM>. The lateral platforms may be configured to extend towards a rear opening <NUM> of the central frame <NUM> more than the central platform. The additional platform <NUM> may be configured to extend less or substantially the same towards the rear opening <NUM> than the central platform <NUM>, as in <FIG>. The difference in extension towards the rear opening <NUM> of the lateral <NUM>, <NUM> and central <NUM> platforms may be seen in <FIG>.

A versatile supporting structure <NUM> may therefore be obtained. Depending on the task to be performed, the supporting structure <NUM> may be configured accordingly. Each time that a particular place may need to be accessed, e.g. during installation or maintenance, mounting a specific support from scratch to access it may be not required. Access to one or more of the rotor <NUM>, the nacelle or central frame lifting points <NUM> and an upper portion of the front flange <NUM> of the central frame <NUM> may be rapidly performed.

As shown in <FIG>, the ladder <NUM> which previously allowed to go to the central platform <NUM> may be moved to allow accessing a lateral platform <NUM>, <NUM> instead the central platform. In other examples, two or more ladders may be used, e.g. one for accessing the central platform and another one for accessing a lateral platform.

In a further aspect of the present disclosure, a method <NUM> for handling a supporting structure <NUM> for use in a central frame <NUM> of a direct-drive wind turbine <NUM> is provided. Any supporting structure <NUM> as described with respect to <FIG> and <FIG> may be used.

The method comprises, at block <NUM>, lifting and introducing the supporting structure <NUM> into the central frame <NUM> while the supporting structure <NUM> is in a stowed configuration. A crane or any suitable lifting tool may be used to lift the folded structure and position it inside the central frame <NUM>.

The method may further comprise folding a first side portion <NUM> and a second opposite side portion <NUM> of the supporting structure <NUM> towards a central portion <NUM> of the structure.

A side portion of the structure <NUM>, <NUM> may be attached by one or more rotatable joints or connectors <NUM> such as hinges to the central portion <NUM>. Other features enabling to rotate a lateral side portion <NUM>, <NUM> towards a central portion <NUM> may be used. For example, a rod or bar may engage a part of a side portion <NUM>, <NUM>, e.g. an end of a beam <NUM>, and a rod or bar may also engage a part of the central portion <NUM>, e.g. a horizontal protrusion, as in <FIG>.

Folding the first side portion <NUM> and the second opposite side portion <NUM> may comprise rotating and sliding the first <NUM> and second <NUM> sides towards the central portion <NUM>. Depending on the structure <NUM>, a side such as a lateral platform <NUM>, <NUM> may be first rotated and then slid or it may be first slid and then rotated. Sliding and rotation may also occur, at least in part, simultaneously. Sliding and rotating may take place as explained with respect to <FIG> and <FIG>.

In some other examples, rotation may not be necessary, but just sliding may be enough. A side portion <NUM>, <NUM> may be slid in a vertical direction, e.g. upwards or downwards, and then it may be slid in a horizontal direction such that it ends at least in part above or below the central portion <NUM>. Other ways of folding and/or sliding the first and second side portions for reducing the dimensions of the supporting structure <NUM> may be possible.

The method further comprises, at block <NUM>, attaching the supporting structure <NUM> to the central frame <NUM>. At least the central portion <NUM> may be attached to an inside of the central frame <NUM>.

The method further comprises, at block <NUM>, deploying the supporting structure <NUM>. Deploying may comprise unfolding one or more side portions with respect to a central portion <NUM>. For example, the first <NUM> and second <NUM> side portions may be rotated to a position which they had before the supporting structure <NUM> was folded. Sliding instead of or in addition to rotation may be used for the unfolding.

In some examples, deploying <NUM> may be performed before attaching <NUM>. The supporting structure <NUM>, once unfolded, may be positioned on an inner flange <NUM> of the bottom of the central frame <NUM>, as in <FIG>. Outer ends or portions of beams <NUM>, <NUM>, <NUM> forming the lateral side portions <NUM>, <NUM> and the central portion may be mechanically attached to the bottom inner flange <NUM>.

The central portion <NUM> may have a column <NUM> configured to guide at least a cable from the central frame <NUM> down a wind turbine tower <NUM>. The column <NUM>, which may be protruding upwards when the supporting structure <NUM> is being lifted inside the central frame <NUM>, may be slid downwards after the lateral side portions <NUM>, <NUM> have been unfolded. The column <NUM> may be slid downwards after at least the central portion <NUM> has been attached to the bottom flange <NUM> of the central frame <NUM>.

In some other examples, attaching <NUM> may be performed before deploying <NUM>. For example, the supporting structure <NUM>, once unfolded, may be positioned on one or more supporting elements <NUM> on a bottom of the central frame <NUM>. One or more supporting elements <NUM> may be attached to an inside flange of a bottom of the central frame <NUM> and/or they may be attached to a bedplate <NUM>. A supporting element <NUM> may be a beam or a leg, e.g. a vertical beam or leg, as in <FIG> and <FIG>. One or more legs <NUM> may be mechanically joined to an edge of a central platform <NUM> configured to face the rear opening <NUM> of the central frame.

Other connection points <NUM> such as beams or legs shorter than supporting elements <NUM> may be used to attach an edge of the central platform <NUM> configured to face a front opening <NUM> of the central frame <NUM> to a bottom portion of a front flange <NUM> of the central frame <NUM>.

A lateral platform <NUM>, <NUM> above the central platform <NUM> may be joined to an inside lateral surface <NUM> of the central frame <NUM> and/or to a front flange <NUM> of the central frame <NUM>. Attachment may be direct or indirect, e.g. through connection points <NUM> such as corner joints. Other pieces may be used for attaching a lateral platform <NUM>, <NUM> to an inside of the central frame. In <FIG>, the lateral platforms <NUM>, <NUM> have been attached to both an inside lateral surface <NUM> and the front flange <NUM>.

In this way, a supporting structure <NUM> for a central frame <NUM> of a direct-drive wind turbine <NUM> may be easily lifted and placed inside the central frame <NUM>. Assembly time in a main line of production, e.g. of a nacelle <NUM>, may be reduced as there is no need to introduce and mount individually each piece of a supporting structure <NUM> in the main line. A basic supporting structure as in <FIG> or <FIG> may be assembled out of the main production line and then folded and lifted into the central frame <NUM>.

With such a supporting structure <NUM>, access to the rotor <NUM> through the frontal opening <NUM> and access to the nacelle <NUM> through the rear opening <NUM> may be easily obtained without the need of temporary platforms or different structures to be assembled depending on the place to be accessed.

Once a relatively basic and simple supporting structure <NUM> has been secured to an inside of the central frame <NUM>, such as the structure of <FIG> or <FIG>, additional components may be added.

Plates <NUM> may be added to one or more of the central portion <NUM> and the first <NUM> and second <NUM> side portions in order to create a floor <NUM>. Floor <NUM> may be a bedplate <NUM> on which e.g. electrical cabinets and other equipment may be placed.

One or more stairs or ladders <NUM>, <NUM>, <NUM> may be added for accessing the support structure <NUM>. A ladder <NUM> configured to extend in a wind turbine tower <NUM> may be provided for accessing one of the first <NUM> and second <NUM> side portions or the central portion <NUM> from an inside of the tower <NUM>. One or more of the ladders may be foldable.

A door <NUM>, <NUM> to regulate access through the front opening <NUM> may also be included.

In the step of deploying <NUM>, the supporting structure may be deployed to a first configuration for accessing a first part of the central frame. The method may further comprise deploying the supporting structure the to a second different configuration for accessing a second different part of the central frame. For example, a first configuration may enable accessing a lower portion of a front flange <NUM> of the central frame and the lifting points <NUM> of the central frame or nacelle, see e.g. <FIG>. A second configuration may enable accessing an upper portion of a front flange <NUM> of the central frame <NUM>, see e.g. <FIG>.

In some examples, where the first side portion <NUM> comprises a first lateral platform <NUM>, and the second side portion <NUM> comprises a second lateral platform <NUM>, the method may further comprise adding, e.g. detachably joining, one or more platform parts <NUM> to the supporting structure <NUM>. The one or more platforms parts may be used when needed for assembling an additional platform <NUM>, e.g. above and between the first <NUM> and second <NUM> lateral platforms.

A platform part <NUM> may be a platform plate <NUM>. A platform part <NUM> may be a supporting element <NUM> for one or more platform plates <NUM>. A supporting element <NUM> may be a rod or beam, such as in <FIG>, but other supporting elements may be used. In some other examples, a platform part <NUM> may be an integral single piece which may be ready to use once placed in an appropriate location.

One or more platform parts <NUM> may be hanged on one or more railings <NUM> previously provided. One or more platform parts <NUM> may for example be attached above the central platform <NUM> as illustrated in <FIG>.

Once the additional platform <NUM> is mounted, an operator may access it from any of the lateral platforms <NUM>, <NUM>. The additional platform <NUM> may enable accessing an upper portion of a front flange <NUM> of the central frame <NUM>.

If the additional platform <NUM> is placed at a height such that access to the lateral platforms <NUM>, <NUM> from the central platform <NUM> is blocked, as in <FIG>, ladder <NUM> or any other suitable tool may be used to access a lateral platform <NUM>, <NUM> and then the additional platform <NUM>.

A versatile and adaptable supporting structure <NUM> may therefore be provided and assembled depending on the task and the place where it needs to be performed. Each time that a particular place may need to be accessed, e.g. during installation or maintenance of the central frame, the nacelle or the wind turbine, mounting a specific support to access it may be not required. Access to one or more of the rotor <NUM>, the central frame or nacelle lifting points <NUM> and an upper portion of the front flange <NUM> of the central frame <NUM> may be rapidly performed.

Still a further aspect of the invention provides another supporting structure <NUM> for a central frame <NUM> of a direct-drive wind turbine <NUM>. The supporting structure <NUM> comprises a first side <NUM> comprising a first lateral platform <NUM>, a second opposite side <NUM> comprising a second lateral platform <NUM>, and a central portion <NUM> comprising a central platform <NUM>. The first <NUM> and second <NUM> lateral platforms are above the central platform <NUM> and they are configured to be rotated and slid with respect to, e.g. towards, the central platform <NUM>.

In an unfolded position, as in <FIG>, the supporting structure <NUM> may have a U-shaped cross-section (in a cross-section including joining elements <NUM> such as stairs).

The first <NUM> and second <NUM> lateral platforms may be configured to enable access to one or more lifting points <NUM> of the central frame <NUM>. The central platform <NUM> may be configured to give access to the rotor <NUM>.

The supporting structure <NUM> may further comprise an additional platform <NUM>. The additional platform <NUM> may be mounted between and above the first <NUM> and second <NUM> lateral platforms. The additional platform <NUM> may be provided in an unassembled state and may comprise one or more platform parts <NUM>, as e.g. in <FIG>, and then be assembled when required as e.g. in <FIG>.

The additional platform <NUM> may be configured to enable access at least to an upper portion of the frontal flange <NUM> of the central frame <NUM>.

The explanation provided with respect to <FIG> may be applied to this supporting structure <NUM>. Similarly, such a supporting structure <NUM> may also be used in a method <NUM> as described above.

Claim 1:
A supporting structure (<NUM>) for a central frame (<NUM>) of a direct-drive wind turbine (<NUM>), characterized in that the supporting structure (<NUM>) is foldable and is configured to assume a deployed configuration, and a stowed configuration, wherein
in the stowed configuration, the supporting structure (<NUM>) is folded and has a shape and size such that the supporting structure (<NUM>) can be introduced into the central frame (<NUM>) from an outside, and wherein
in the deployed configuration, the supporting structure (<NUM>) is unfolded and has one or more increased dimensions with respect to the stowed configuration, and comprises a working platform.