Integrated tackle system for wind turbine maintenance

Abstract

The invention relates to an integrated tackle system for wind turbine maintenance, which comprises at least one elongate rib (100) attached by the ends thereof to the interior surface of a hub (200), in the manner of a bridge that spans a respective opening of a rolling bearing (300) for changing the pitch of a corresponding blade (400) of the wind turbine, the rib (100) being designed to have a tackle (500) attached thereto, and guiding coupling means for coupling / uncoupling the blade (400) such that same can be lifted / lowered using the tackle (500).

Description

[0001]

[0002] INTEGRATED HOIST SYSTEM FOR WIND TURBINE MAINTENANCE

[0003] Technology sector

[0004] The present invention relates to the technical sector of wind turbines in the field of wind energy production. More specifically, the invention is applicable to the maintenance, installation, and servicing of such wind turbines; it relates, in particular, to a detachable and modular hoist system integrated into the wind turbine to facilitate the lifting, raising, assembly, and disassembly of the various components that make up the vertical support tower of the wind turbine.

[0005] State of the art

[0006] Wind turbine maintenance represents one of the biggest economic and logistical challenges in the wind energy industry. The need to use large cranes for the maintenance and replacement of critical components located in or connected to the turbine nacelle, such as the hub, blades, and main bearings, not only significantly increases operating expenses (OPEX) but also reduces the operational availability of wind turbines due to the associated long downtimes, resulting in significant lost profits for the wind farm design.

[0007] Currently, crane rental and heavy equipment mobilization represent a significant proportion of the operating expenses (OPEX) for wind turbine maintenance. These costs are not only due to prohibitively high rental rates but also to the limited availability of suitable cranes, forcing turbines to remain idle for extended periods. Prolonged power outages have a direct negative impact on the profitability and ability of wind farm operators to meet their energy generation targets.

[0008] In the prior art, several patents and technological solutions exist that address the use of integrated cranes or hoists to facilitate wind turbine maintenance. These patents include systems for loading and unloading blades, and some even address the problem of tilt and conning (inclinations, rocking, or rotational movements, and similar issues, during the lifting and lowering of different wind turbine components) during maintenance operations. This problem is particularly pronounced when handling wind turbine blades due to their large size and elongated shape, which hinders the correct positioning of their connection ends relative to the hub during installation.Furthermore, although the solutions referred to represent significant advances, none has managed to provide a comprehensive solution that allows for the complete maintenance of a wind turbine without the need for external cranes.

[0009] In particular, only one solution is known that partially addresses the tilt and conning problem, but none effectively resolves how to unload and handle the hub or main bearings using only integrated hoists. This gap in the prior art underscores the need for an innovative solution that enables comprehensive maintenance of wind turbines without resorting to external cranes.

[0010] For example, we can specifically mention documents EP4010588B1 and EP2363598B1, where the system disclosed in the former comprises an extendable section for moving components from inside the nacelle to a lower opening in the rear of the nacelle, and the system in EP2363598B1 comprises an extendable section for removing components from the rear of the nacelle. However, currently no system is known that allows the unloading and loading of wind turbine hubs without an external crane under the operational and structural conditions disclosed by the present invention.

[0011] Regarding the vertical loading and unloading of the blades, reference can be made to Nabra Wind Technologies patent WO2023281127A1 (and the corresponding patents mentioned therein) or to patent ES2772673T3. In this respect, only Nabra's patent provides a solution for centering the blade with the pitch change bearing for mounting it on the wind turbine hub. This solution uses various hoists, stiffening plates, and bolts to center the blade on the bearing; this is a very compact system that is located inside the hub, as it is designed for existing machines where there is very little space between the outer fairing and the hub. It differs substantially from the solution provided by the present invention in relation to the problem of centering or orienting the blades during assembly.

[0012] The invention solves at least some of the aforementioned problems, enabling safe and efficient handling of the blades, and additionally the hub, main bearings, and power train components, all while eliminating dependence on external cranes. The competitive advantages of this system are clear: a drastic reduction in the costs associated with crane rental and mobilization, greater efficiency in maintenance operations, and increased flexibility in managing these operations over time, allowing wind farm operators to maximize energy production and optimize the profitability of their assets. Furthermore, as will be demonstrated from the features described in detail in subsequent sections of this document, the system of the invention offers a high level of flexibility thanks to the vapor-resistant core of its components.

[0013] Object of the invention

[0014] According to the objectives set forth in the preceding section, the object of the present invention is an integrated hoist system for wind turbine maintenance, of the type comprising one or more structures or frames for mounting one or more hoists for raising / lowering the wind turbine blades or components installed in the nacelle. The system of the invention comprises one or more elongated ribs. The ribs are mounted through the openings in the hub where the wind turbine blades are normally mounted and through the interior of said hub, thus forming a support for the installation of a hoist intended to raise / lower a corresponding blade. These ribs can be fixed, for example, with suitable screws and bolts commonly used in the industry.The ribs may also include transverse reinforcing elements (if two or more are installed, which is a preferred embodiment), and these elements may be located at the ends where the ribs are attached to the hub and / or in intermediate sections between these attachment points. Furthermore, these reinforcing elements may be substantially perpendicular to the ribs or inclined with respect to them. The system also includes guided coupling means for attaching / detaching the blade for raising / lowering by means of the hoist.

[0015] Thanks to this configuration, a wind turbine blade can be easily removed without the need for an external crane, as the wind turbine itself has the hoist system installed inside, allowing for the replacement or maintenance of the blade, thus reducing both the time and costs associated with said maintenance.

[0016] Preferably, according to a feature of the invention, the elongated ribs are longitudinally curved; these ribs can also be detachable from the hub. In a preferred embodiment, the system comprises exactly two substantially parallel ribs. Regarding the aforementioned hoist attachment, the ribs can include a platform specifically adapted for this purpose, for example, such that the platform passes through the plurality of ribs. The curved configuration contributes to better weight distribution, avoiding oversizing the rib and providing greater system safety.

[0017] Preferably, according to another feature of the invention, the system comprises at least one attachable lug (for example, by screwing, structural adhesive (for example, but not limited to epoxy), or welding) to the wind turbine blade with at least one attachment hole for a corresponding hook end of a hoist. The material of these lugs or other similar parts comprising the attachment holes may preferably comprise fiberglass (for example, like the wind turbine blades). Thanks to this configuration, the blade structure remains intact, preventing potential holes that could weaken its integrity.

[0018] According to another feature of the invention, the guided coupling means are in the form of a converging positioning nozzle. The nozzle has a proximal end relative to the hub, which is mounted on the hub (on its outer side) around the opening of the pitch change bearing of the blade on which the blade is mounted. Its other end, the distal end, is where the blade is inserted during hoisting, to correctly position the blade's connection end around the hub's connection opening as the blade reaches the proximal end of the nozzle. At this point, and once the blade is correctly positioned, the operators can proceed with the assembly operations by screwing and similar means.The nozzle's characteristics, therefore, are its dimensions and internal geometry, which progressively guide the blade's connecting end during its lifting motion to the hub. This ensures that, upon reaching the hub, the connecting end is correctly positioned and aligned for secure attachment. The nozzle can also assist in the lowering or unloading of the blades.

[0019] Preferably, according to a further feature of the invention, the inner surface of the converging positioning nozzle facilitates the sliding of the blade being raised / lowered through it. More preferably, in a preferred embodiment, the surface may accept lubricants, may comprise materials that facilitate such sliding, such as Teflon, and may comprise rolling elements, such as wheels, rollers, spheres, and the like, on which the corresponding blade can move smoothly.

[0020] Preferably, another feature of the system of the invention relates to the medullary nature of the positioning nozzle. More preferably, in a preferred embodiment, the medullary nature of the nozzle is achieved by means of a series of elongated elements (in the longitudinal direction from one end of the nozzle to the other), which we herein call petals, and which are mounted side by side constituting the typical nozzle shape.

[0021] In another preferred embodiment, the characteristics that these petals may have are a rectangular shape, a curvature that protrudes into the nozzle, a thickness that gradually decreases from its proximal fixing end to its distal end (the one furthest from the hub), fixing bases for mounting on the hub (which may be integral with the petal itself, for example, by bending it to form a section substantially perpendicular to the longitudinal body of the petal, or they may be separate pieces firmly fixed to the proximal end of each petal) and positioning housings comprising around the opening of the hub's pitch change bearing and adapted to receive the aforementioned fixing bases; these housings may also be integral with the hub or separate pieces fixed to it.

[0022] In another preferred embodiment, each of the positioning housings corresponds to only one of the fixing bases, and vice versa, so that there is no possibility of error in the assembly of the petals, to achieve the shape and geometry of the nozzle that allows the correct guidance of the blade (Poka Yoke system, in Japanese, “error-proof”).

[0023] Regarding the shape and geometry of the nozzle, its distal end, according to another feature of the invention, is oblique with respect to the nozzle's longitudinal axis. Its arrangement is such that the longest part of the nozzle (due to this oblique distal end) is the part closest to the generator tower in its operating position. That is, in the case of the modular nozzle with petals, there would be longer and shorter petals (of varying lengths that progressively increase from a minimum to a maximum), and the longer petals would be fixed closer to the tower.

[0024] According to another alternative feature of the invention, the guided coupling means are in the form of a guide lance, an elongated element that can be detachably fixed into an opening in the hub where a corresponding blade is to be installed / detached. The blade, in turn, comprises an elongated cavity that corresponds in shape and geometry to the guide lance, guiding the latter and, consequently, the blade along its path. The entrance to the elongated cavity may include a hopper-shaped opening to easily capture or collect the lance and guide it into the cavity.

[0025] Preferably, according to a further feature of the hoist system of the invention, it includes a sliding trampoline structure along the longitudinal axis of the nacelle of a wind turbine. For this purpose, the sliding trampoline structure comprises a fixed frame, attachable to the tower area, and a movable frame (which would be the trampoline itself) that slides towards and over the hub area. Once extended, the hub can be accessed by the appropriate operators from this trampoline. The same hoist referred to above, or a different one, can be installed on both the fixed and movable frames.

[0026] Additionally, preferably, the system comprises a bridge crane structure with its corresponding frame; a hoist can be attached to said bridge crane, which can be the same one used for the subsystem of the elongated ribs, and it can be moved between the area of ​​the wind turbine tower and the rear of the nacelle, where there can be a door or hatch for the passage up / down of the different detachable components that are in said nacelle.

[0027] Preferably, the frame of the bridge crane structure and the fixed frame of the sliding trampoline could be a single structure or frame, without a physical discontinuity in terms of the constituent parts; in such a case, the designations “frame of the bridge crane structure” and “fixed frame” of the trampoline structure are used for purely illustrative, conceptual purposes, in order to adequately explain the invention.

[0028] Preferably, according to another feature of the invention, sliding between the moving frame and the fixed frame of the trampoline structure can be achieved by means of tracks, guides, rails, and the like. Wheels, casters, spheres, rollers, and other elements that facilitate mutual rolling or sliding while providing sufficient support can be incorporated between these elements. These rolling elements could be positioned in three different locations, for example, gripping the moving frame at its top, its bottom, and its longitudinal edge, thereby providing greater stability during sliding and improved positional retention of the moving frame.

[0029] Finally, according to another feature of the invention, the bridge crane structure, the sliding platform structure, the mobile frame, and the support ribs corresponding to each blade comprise the same configuration suitable for attaching a single hoist, which can be fixed to any of them depending on the requirements. In this way, the wind turbine incorporating this maintenance system will not require the use of external cranes, since with this hoist system any of the components of the wind turbine nacelle can be disassembled using a single hoist that is valid for any of the structures. Furthermore, preferably, this hoist will have a suitable weight and span to allow an operator to move it from one location to another, facilitating maintenance work.

[0030] Description of the figures

[0031] The drawings attached to this document are listed and briefly described below, by way of non-limiting example, to illustrate and facilitate the interpretation of the integrated hoist system disclosed in this invention.

[0032] Figure 1 is a perspective and cross-sectional view of a bushing and a blade mounted thereon for polishing the ribs for fixing hoists of the present invention.

[0033] Figure 2 is a side view of a wind turbine, specifically showing the tower, the nacelle with its front open or in section to show the converging positioning nozzle and a blade hanging from a corresponding hoist.

[0034] Figure 3 is a view similar to Figure 2 but from a lower side, with the rest of the nacelle open and with a generator hanging from another corresponding hoist.

[0035] Figure 4 is a perspective view of the system of the present invention, with the gondola fully in section to appreciate the sliding trampoline structure at the front and the bridge crane structure at the rear.

[0036] Figures 5 and 6 are two views of the sliding trampoline structure with the latter in a folded and extended position, respectively.

[0037] Figure 7 is a detail view of an alternative embodiment for coupling the blade during lifting.

[0038] Detailed description of the invention

[0039] A detailed description of the invention will then be carried out with reference to the figures outlined in the previous section.

[0040] Figure 1 shows a cross-section of the hub (200) of a wind turbine, as well as a corresponding blade (400) with ribs (100) installed across the opening of a blade pitch change bearing (300). These ribs (100) are arranged to allow the installation, preferably temporary, of a hoist (500) for raising or lowering a blade (400), with the hoist cable (500) passing through the bearing opening (300). A curved shape for these ribs (100) is considered most suitable due to its optimal transmission and distribution of forces, although the invention contemplates any other shape that a manufacturer might deem appropriate, prioritizing other aspects such as ease of assembly or handling.It is also considered that the installation of two ribs (100) is sufficient to conveniently mount a hoist (500) on them, offering sufficient robustness and resistance for the weight of, for example, a shovel (400). This does not preclude a different number of ribs (including simply one wider rib or one with a reinforced structure, i.e., as if they were two or more ribs integrated into a single structure with transverse reinforcing elements). This preferred embodiment of the figures includes two independent ribs (100) to facilitate handling, assembly, and disassembly by the operators.

[0041] In said figure 1, a kind of support and reinforcement platform or plate can also be observed that connects the corresponding ends of two ribs (100) and also connects said ends with the inner surface of the hub (200); these platforms or plates can be an integral part of the hub (200), they can be independent pieces fixed to the hub (200) (and which can be left permanently installed on it or can be removed after each maintenance / service operation) or they could also be parts or pieces integrated into the structure of one or more of the ribs (100).

[0042] The ribs (100) have fixing means for the hoist (500), and these fixing means can be simple screw holes or specific parts or pieces in the form of, for example, platforms or plates. Preferably, these fixing means are distributed along the ribs (100) so that the hoist (500) can be mounted in different longitudinal positions along them, for example, with multiple screw holes along the ribs (100). One of the preferred shapes for the ribs (100) is an angle profile, as can be seen in the figures, so that one of the faces of the profile acts as a flat surface for fixing the hoist (500) directly or a hoist fixing platform or plate (500).

[0043] The complete system (including the ribs (100) of each bearing opening (300) as well as the structures (800) and (900) described later) can be arranged to accommodate the use of a single hoist (500) that can be disassembled and reassembled in one or another subsection of the system as required. Thus, the weights of both the hoist(s) (500), or any modules into which it may be disassembled, and the modular components of the system (e.g., ribs (100)) are designed to be transportable and manageable by one or two operators working within or around the nacelle.

[0044] Figure 1 also shows lugs (420), preferably made of fiberglass, for hanging the blades (400) from the hoist (500). These lugs (420) can be attached to the inner surface of each blade (400) or manufactured as an integral part of the blade itself. The lugs (420) have corresponding holes (410) for attaching the appropriate hook (510) of a hoist (500). If the lugs (420) are not required, the holes (410) can be made in other similar components or directly in the blade body (400).

[0045] The hoist (500) and ribs (100) are also designed for loading and unloading the pitch change bearings (300), the pitch change system actuators, and the fiber covers of the aerodynamic hub fairing (200) (“spinner”).

[0046] To orient and center the blades (400), the invention comprises guided coupling means, including a converging positioning nozzle system (600) designed to be fixed in the bearing opening (300) and such that, at its end furthest from said opening, it can receive a blade (400) being lifted and guide it into proper alignment with the bearing (300) for securing by operators. This nozzle (600) is preferably modular, as shown in Figure 2, where it consists of a series of elongated petals (610) which, when mounted side by side around the bearing (300), create the shape of a nozzle (600).The geometry and shape of said nozzle (600) (and, therefore, of the modular elements that constitute it, in this case the petals (610)) are such that they orient the connection end of the corresponding blade (400) to its connection with the bearing (300) and also the position of the rest of the blade (400) to avoid, as far as possible, tilting movements, turns, swings or even impacts with the tower.

[0047] Preferably, the hub (200) comprises positioning housings (or sockets) (620) for receiving the fixing ends of the petals (610), and in one embodiment, fixing bases are included at said ends. The housings (620) can be manufactured, for example, by casting from the hub (200) itself. The preferred, though not exclusive, material for the petals (610) (or whatever the modular element constituting the nozzle (600) may be) is carbon fiber due to its strength and light weight characteristics, with the appropriate weight for each petal being considered to be less than 25 kg.

[0048] One of the preferred shapes of the converging nozzle (600) is such that it forms an oblique distal end (as can be seen more clearly in Figure 2) where the longer part of the nozzle (600) is closest to the tower. In the preferred case of the modular nozzle (600) with petals (610), the longer petals (610) are mounted closest to the tower. Furthermore, as with the components described earlier, these petals (610) have dimensions and weight suitable for handling by one or two operators from, for example, the hub (200) of the wind turbine.

[0049] The distance between petals (610) shown in the figures is illustrative and, in other embodiments, could be greater or lesser depending on the characteristics of the contour of the blade's connecting end (400) to ensure proper guidance of the blade (400) with the use of the least amount of material possible. The preferred shape is that of rectangular petals (610) with a bulge or curve towards the interior of the nozzle (600), as these characteristics have been observed to facilitate the guidance of the corresponding blade (400).

[0050] On the other hand, the nozzle (600) may comprise a material on its inner surface (for example, the entire nozzle material (600) or a mixture with other materials, or a coating, or similar) to facilitate the sliding of the blade (400) across that surface. Preferably, lubricants or greases, for example, long-life lubricants, may also be applied for this purpose.Another feature that the nozzle (600) could include (for example, in some or all of the petals (610)) would be rolling elements that further facilitate the guidance of the blade (400): rollers, spheres, wheels, casters, etc. These rolling elements could be installed in through grooves made in the petals (610) (or in any other modular element of the nozzle (600) that adopts another geometry or on its continuous surface in the case of integral nozzles (600)) and would be held within these grooves with pivot axes such that part of the rolling elements protrudes outside the inner surface of the nozzle (600) and the blade (400) can roll / slide on them.

[0051] According to an alternative of the invention, as shown in Figure 7, the guided coupling means comprise a guide lance (700) in the form of an elongated element that can be detachably fixed in an opening of the hub (200) in which a corresponding blade (400) is to be installed / detached. The blade (400) comprises an elongated cavity (not shown in the figures), corresponding in shape and geometry to the guide lance (400) for guiding the latter and, therefore, the blade (400) along its travel. The entrance to the elongated cavity may include a hopper-shaped opening to easily capture or collect the guide lance (700) and guide it into the cavity to engage the blade (400) during its installation in the bearing (300).

[0052] Figure 4 illustrates a bridge crane structure (800) and a sliding platform structure (900) that are also part of one of the preferred embodiments of the invention. The bridge crane structure (800) comprises a respective frame (810) that supports the movable part of the structure (800); this movable part is arranged for the attachment of a hoist (500) and can be moved between a rear portion of the wind turbine nacelle (corresponding to a lower discharge door or hatch) and the turbine tower.The frame (810) of the structure (800), the structure itself (800) (including the motor and sliding parts), and the hoist (500), along with the unloading hatch, are arranged for unloading and raising converters, generators, gearboxes, or the entire assembled unit, the various distributor components, or the rear main bearing. They may also have the capability of removing the entire powertrain (for powertrains designed as a package). Furthermore, the nacelle includes a door for lowering, for example, a generator, as shown in Figures 3 and 4.

[0053] The movable frame (920) of the structure (900) is configured so that, in one of its extreme positions, it cantilevers over the hub area (200), and in its other extreme position, it is recessed within the fixed frame (910) and thus does not obstruct the rotation of the wind turbine blades (400). This movable frame (920) allows for the removal and raising / lowering of, for example, the hub (200) and the front main bearing, thus providing direct access to the aforementioned bearing. As shown in Figure 4, the structure (900) is preferably configured to match the geometry of the nacelle's inner surface, with substantially circular transverse ribs complemented by longitudinal stringers.

[0054] Next, two illustrative examples of operations facilitated by the system of the present invention are presented.

[0055] In the first instance, the main front bearing needs to be replaced, which is one of the most arduous tasks in wind turbine maintenance. The probability of this operation occurring should be negligible, given the bearing's size and the low normalized mechanical load on each roller involved, which should minimize structural degradation of the bearing. Nevertheless, it is worth mentioning here precisely because of its complexity. It is necessary to remove the hub (200), and the following steps can be followed:

[0056] 1. The wind turbine is stopped and the rotor is braked with one blade (400) pointing towards the ground (typically by means of an electric brake).

[0057] 2. A hoist (500) is installed on the ribs (100) inside the hub (200) and the blades (400) are unloaded (following, for example, the procedure described below).

[0058] 3. From these same ribs (100), one of the spinner modules is unloaded; that is, the fairing that covers the hub (200) with a certain separation from it and which is composed of three equal segments. In this case, one of them must be removed. This element is lowered in a similar way to how the blades (400) are lowered, with the same hoist (500), by picking up the piece from some hoisting points (attachment points for the hoist (500)) located in the circular opening through which the blade (400) is centered in the operating position.

[0059] 4. Once that segment of the fairing has been removed, it is turned 180 degrees to face upwards.

[0060] 5. After this, the movable frame (920) is extended and the hoist (500) is attached to it (for example, by means of a screw connection); it is hooked to the hub (200), specifically to its attachment points (usually rings or eyelets) inside the hub (200).

[0061] 6. Unscrew the flange connection of the hub (200) to the main shaft and lower the hub (200) with the two fairing segments. At this point, you have access to the main bearing.

[0062] 8. Next, the bearing and the "main housing" are heated by induction so that the expansion allows the bearing to be extracted from the front, which will be attached to the hoist (500) by the attachment points, and it can then be lowered.

[0063] It should be noted that both this procedure and the subsequent one explained below are merely illustrative, and the details may vary depending on the specific wind turbine, the operators' customs and expertise, and similar technical aspects. These examples, however, serve to illustrate the operational advantages provided by the present invention. The procedure just described will generally be carried out in reverse order to achieve the operational assembly of the disassembled parts.

[0064] The following are the steps of a procedure for raising / lowering the blades (400) using the mechanism with the ribs (100) inside the hub (200):

[0065] 1. The wind turbine is stopped and the rotor is blocked with one blade (400) facing the ground.

[0066] 2. Each of the petals (610) of the modular nozzle (600) are installed, each of which is fixed in a specific position of the hub (200) (poka yoke system).

[0067] 3. The hoist (500) is attached to a platform which, in this embodiment, forms part of the ribs (100) by means of a bolted joint.

[0068] 4. The blade (400) is attached to the hub hoist (500) by means of its attachment points or holes (410) and the joint is then tensioned.

[0069] 5. Unscrew the screws connecting to the pitch change bearing (300).

[0070] 6. The blade (400) begins to be lowered, following the curve described by the passive positioning convergent nozzle (600).

[0071] 7. Upon reaching the bottom, a small truck crane will suffice to place the shovel (400) horizontally and support it on specific tools on the ground.

[0072] As can be deduced from the described embodiments and others that will be derived from the claimed features developed herein, the present invention offers improvements related to the maintenance, installation, and dismantling of wind turbines and their various components in a flexible, modular manner, integrated into the generator itself, without the need to rely on large and costly cranes whose availability is not always guaranteed. Therefore, maintenance operating expenses (OPEX) are significantly reduced, downtime is minimized, and the operational availability of the wind turbines is increased.

Claims

CLAIMS 1. Integrated hoist system(s) for wind turbine maintenance, comprising at least one elongated rib (100) fixed at its ends to the inner surface of a hub (200), as a bridge crossing a respective opening of the pitch change bearing (300) of a corresponding wind turbine blade (400), said rib (100) being configured to fix a hoist (500) thereon, and guided coupling means for coupling / uncoupling the blade (400) for raising / lowering by means of the hoist (500).

2. System according to claim 1, wherein the elongated rib (100) is curved towards the inside of the hub, and / or is detachably fixable.

3. System according to any of the preceding claims, comprising at least one lug (420) attachable to the blade (400) of the wind turbine with at least one attachment hole (410) for a corresponding attachment end (510) of the hoist (500). 4 System according to any of the preceding claims, wherein the guided coupling means are in the form of a converging positioning nozzle (600), mountable at one of its proximal ends around the respective opening of the pitch change bearing (300) and with its distal end away from the hub (200), such that said nozzle (600) is detachable and is arranged, in its operative position, to guide and progressively orient the connecting end of a blade (400) suspended from the hoist (500) in its path between the proximal end and the distal end, and vice versa, of the nozzle (600).

5. System according to the preceding claim, wherein the inner surface of the nozzle (600) is adapted to facilitate the sliding of the corresponding blade (400) over it in its path between the proximal end and the distal end, and / or vice versa, of the nozzle (600).

6. System according to the preceding claim, wherein the inner surface of the nozzle (600) comprises a plurality of rolling elements to facilitate the sliding of the blade (400).

7. System according to any of the preceding claims, wherein the end The distal part of the nozzle (600) is oblique, so that the longest longitudinal part of said nozzle (600), in the operating position, is closest to the vertical axis of the wind turbine tower.

8. System according to any one of claims 4 to 7, wherein the converging positioning nozzle (600) comprises a plurality of elongated petals (610), the proximal petal ends being configured to be fixed around the pitch change bearing opening (300) corresponding to the blade (400).

9. System of the preceding claim wherein each corresponding petal fixing base (610) is adapted to be mounted in only one respective of the relevant positioning housings (620).

10. System according to any of claims 1 to 3, wherein the guided coupling means are in the form of a guide lance (700) detachably fixable in an opening of a pitch change bearing (300) and wherein the connection end of the blade (400) comprises a hopper-shaped structure and an elongated cavity into the blade (400), such that during the lifting of the blade (400), the guide lance (700) threads the elongated cavity, guiding the blade (400) to a correct positioning in the pitch change bearing (300).

11. System according to any of the preceding claims, comprising a sliding trampoline structure (900) in the longitudinal direction of the nacelle of a wind turbine, and comprising a fixed frame (910) fixable inside the nacelle on the wind turbine tower, and a movable frame (920) movable between a retracted position overlapping the fixed frame (910) and a cantilevered position over the hub (200) of the wind turbine, the movable frame (920) and / or the fixed frame (910) being adapted for the attachment of a hoist (500).

12. System according to the preceding claim, wherein the fixed frame (910) and the movable frame (920) of the sliding trampoline structure (900) comprise complementary sliding rails and / or guides (930) and / or rolling elements (940) interposed between said rails and / or guides (930).

13. System according to any one of the preceding claims, comprising a bridge crane structure (800) comprising a frame (810) attachable to the part of the nacelle of the wind turbine corresponding to the power train, the structure (800) being configured for the attachment of the hoist (500).

14. System according to any of claims 12 and 13 wherein the bridge crane structure (800) and the fixed frame (910) of the sliding trampoline structure (900) are a single frame.

15. System according to any of the preceding claims, wherein the bridge crane structure (800), the sliding trampoline structure (900), the movable frame (920), and the corresponding support ribs (100) for each blade (400), comprise the same configuration suitable for the attachment of the same hoist (500) which can be attached to any of them depending on the needs.

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