Patent Publication Number: US-2023159309-A1

Title: Wind turbine lifting arrangement

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to PCT Application No. PCT/EP2021/059366, having a filing date of Apr. 12, 2021, which claims priority to EP Application No. 20382306.7, having a filing date of Apr. 16, 2020, the entire contents both of which are hereby incorporated by reference. 
    
    
     FIELD OF TECHNOLOGY 
     The following relates to a wind turbine lifting arrangement. 
     BACKGROUND 
     To install or deinstall components of the wind turbine in the nacelle of the wind turbine, a lifting device, such as a crane, is necessary to lift the heavy components, such as a generator or a gearbox, of the wind turbine into or out of the nacelle. 
     In one solution known from the state of the art the lifting device is placed on top or inside of the nacelle and on a top section of the tower. However, to mount the lifting device on top of the nacelle it is typically unavoidable to loosen bolted joints of the nacelle. However, the bolted joints are safety-relevant and thus the loosening of these bolted joints should be avoided. Further, the lifting device placed on top or inside of the nacelle requires or at least obstructs assembly space within the nacelle. Therefore, the operation of the lifting device is typically limited in regard to the components which may be reached and lifted and the movability of the lifting device. 
     In another solution from the state of the art a lifting platform having the lifting device is attached to the tower. To attach the lifting platform to the tower it is known to provide the lifting platform with grippers for gripping the tower. Thereby, large gripping forces are applied to the tower possibly damaging the tower. Further, the lifting device when operated applies very large compressive loads to the top section of the tower, which may result in a damage to the tower and should be avoided. Also, such a lifting platform is expensive and rather difficult to operate. 
     U.S. 2018/0335023 A1 describes a nacelle component for a nacelle of a wind turbine having a rotor shaft having a rotational axis. The nacelle component comprises a mainframe module and a power electronics module. The nacelle component has an assembled state wherein said power electronics module is mounted to said mainframe module with a longitudinal axis of said mainframe module being oriented parallel to the rotational axis of the rotor shaft. The longitudinal axis of said power electronics module intersects with a vertical plane that is parallel to the longitudinal axis of said mainframe module. 
     WO 2019/042506 A1 describes a wind turbine comprising a tower, a nacelle mounted on the tower, and a movable container mounted on a lower part of the nacelle. The movable container is housing a hoisting mechanism for hoisting and/or lowering the movable container and for hoisting and/or lowering wind turbine components. 
     U.S. 2008/0257844 A1describes an independent mobile crane system for temporarily use for moving or replacement of components during service operations and during erection of wind turbine generators comprising an auxiliary gantry crane forming a gantry frame conformed to rotate around the nacelle according to a rotation axis. The independent mobile crane system has a hoisting device integrated in the crane system arranged to allow the crane system to be self-hoisting, in that the independent mobile crane system docks to the nacelle via a docking unit and in that the independent mobile crane system is arranged to operate above the nacelle and on the outside of the nacelle sides. 
     SUMMARY 
     An aspect relates to provide a wind turbine lifting arrangement not having the disadvantages as mentioned above, such that the lifting device is easy to install at the wind turbine, is operable with ease and high movability and is not applying possibly damaging loads onto the tower. 
     According to embodiments of the invention, the aspect is solved by a wind turbine lifting arrangement comprising a tower of a wind turbine, a nacelle of the wind turbine being, a lifting platform and a lifting device attached to the lifting platform for lifting components of the wind turbine to be installed in the nacelle or deinstalled from the nacelle, whereby the nacelle comprises a main frame attached to a top section of the tower, and whereby an attachment portion of the lifting platform is arranged underneath the nacelle and attached to the main frame. The lifting platform comprises a lifting device portion provided adjacent to the attachment portion, the lifting device is attached to the lifting platform in the lifting device portion and the lifting device portion and the lifting device are arranged next to a longitudinal side of the nacelle, whereby the longitudinal side of the nacelle is one of two opposite longitudinal sides of the nacelle extending along a longitudinal axis of the nacelle and arranged between a top side and bottom side of the nacelle. 
     By attaching the lifting platform with is attachment portion underneath the nacelle to the main frame of the nacelle, the bending loads applied to the lifting platform due to operation of the lifting device are transferred to the main frame rather than the tower, whereby the tower is prevented from damage. Further, on the lifting platform, the lifting device is free to move and may be operated with ease. Also, the lifting platform may be easily attached to and detached from the main frame and consecutively the lifting device may be easily attached to the lifting platform. Thereby, in the wind turbine lifting arrangement of embodiments of the invention, the lifting device is easy to install on the lifting platform attached to the main frame of the nacelle, is operable with ease and high movability and is not applying possibly damaging loads to the tower. 
     The lifting device is arranged next to a longitudinal side of the nacelle. That the lifting device is arranged next to the longitudinal side of the nacelle in particular means that it is arranged opposite of that longitudinal side or, in other words, faces the longitudinal side. The nacelle comprises two opposites longitudinal sides as sides in between the top side and the bottom side of the nacelle and extending along the longitudinal axis of the nacelle. The longitudinal sides are located opposite from one another on the nacelle. Further, they may be arranged parallel to one another. Arranged at the longitudinal side, the lifting device is provided with a particularly high mobility and may access and lift all components in the nacelle. 
     The lifting platform may in particular extend away with its lifting device portion from the bottom side of the nacelle, where it may be attached with its attachment portion to the main frame. The lifting device may be supported or, in other words, rested on top of the lifting device portion of the lifting platform. The lifting device portion thereby may only be the portion of the lifting platform which extends out of the plane of the nacelle or, in other words, away from the nacelle. The lifting device portion may have an extension of at least 0.5 m, in particular of at least 1 m or at least 2 m, for example. The extension thereby may be such that the lifting device may be safely rested and secured with its dimensions on top of the lifting device portion of the lifting platform. 
     That the lifting platform is arranged underneath the nacelle in particular means that the lifting platform is arranged at the bottom side of the nacelle. The bottom side of the nacelle is the side facing the ground when the nacelle is supported on the tower. Further, the lifting platform may thereby be arranged facing the tower. Also, the lifting device portion may be extending along the longitudinal axis of the lifting platform. The lifting platform, in particular its lifting device portion, may generally have a plate shape. The lifting device may be supported on top of the lifting device portion or, in other words, rest on the lifting device portion. 
     It is desirable that the lifting platform extends along its longitudinal axis in a direction transverse, in particular perpendicular, to the longitudinal axis of the nacelle. Thereby, the lifting platform may be attached to the main frame along the entire width of the nacelle such that a very secure attachment is provided. 
     Further, it is desirable, that the lifting device portion comprises a carriage for the lifting device. Moreover, it is desirable, that the carriage is configured slidable such that the lifting device can be moved along the lifting platform and closer to or further away from the nacelle. Thereby, the lifting device can be positioned optimally with respect to the nacelle. 
     Also, it is desirable, that the lifting platform comprises two beams attached to the main frame. The beams give structural support to the lifting platform and may be easily attached to the main frame by means of bolted joints, for example. The beams may be designed as I-beams, for example. 
     Therein, it is desirable, that the two beams are arranged parallel to one another. Thereby, even distribution of bending loads from the lifting device along the two beams of the lifting platform and the main frame may be achieved. 
     Further, therein, it is desirable, that the lifting device is attached to a carrying structure of the lifting platform connecting the two beams with each other. The carrying structure is secured to the two beams and allows for carrying the weight and bending loads of the lifting device to the main frame via the two beams. The carrying structure may comprise the lifting device portion and/or the attachment portion of the lifting platform. 
     Also, therein, it is desirable, that the carrying structure is designed as a carrying plate. Thereby, the design of the lifting platform is thin and lightweight. 
     It is desirable, that the lifting platform comprises a support structure arranged underneath the lifting device, the support structure extending parallel to the tower and the support structure being arranged to be pressed against the tower when the lifting device is loaded with a component of the wind turbine. The support structure prevents that excessive bending loads are applied to the lifting platform and transferred therefrom to the main frame which may be harmful to the lifting platform and the main frame. Instead, a portion of the bending loads introduced into the lifting platform, when the lifting device is loaded and rotated, is shifted to the tower. However, contrary to the solutions in the state of the art, these are not applied to the top portion of the tower but instead, in particular evenly, distributed at an upper portion of the tower along the length of the tower by means of the support structure due to its extension along the tower. The top portion of the tower has the top side of the tower whereas the upper portion is a portion of the tower next to the top portion and extending downwards along the tower but not having the top portion, i.e. the top side. The support structure may be attached to the lifting platform, in particular the two beams, and/or to the lifting device. The support structure may be arranged resting on the tower, in particular on the upper portion of the tower. 
     Therein, it is desirable, that the support structure has a concave side corresponding to and facing a rounded shape of the tower. Thereby the concave side of the support structure is forced against the rounded shape of the tower when the support structure is pressed against the tower when the lifting device is loaded and rotated with a component of the wind turbine. The support structure may in particular be arranged to form-fit with its concave side to the tower. The portion of bending loads shifted to the support structure may therefore be transferred to the tower in a particular even manner. 
     Further, therein, it is desirable, that the support structure is designed as an elongate body. For example, the elongate body may be a cylinder. Thereby, the support structure may distribute the portion of the bending loads over a large length of the tower. 
     Also, it is desirable, that the attachment portion of the lifting platform is arranged at or within 5 m distance, in particular within 2 m distance, to the tower. Thereby the path of the bending loads from the lifting platform via the main frame to the tower is kept small and possible damage of the tower is prevented. 
    
    
     
       BRIEF DESCRIPTION 
       Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein: 
         FIG.  1    a side perspective view on the operation of installing a lifting device at a wind turbine; 
         FIG.  2    a side perspective view on a wind turbine lifting arrangement according to a first embodiment of the invention as installed according to  FIG.  1   ; 
         FIG.  3    a side perspective view on a wind turbine lifting arrangement according to a second embodiment of the invention; and 
         FIG.  4    a side perspective view on the wind turbine lifting arrangement of  FIG.  3    in operation of its lifting device. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    shows a side perspective view on the operation of installing a lifting device  30  at a wind turbine  10  to be installed. 
     The wind turbine  10  comprises a tower  11  and a nacelle  12 . The nacelle  12  has a main frame  13  as a structure supporting components  14 ,  15  of the wind turbine  10  inside of the nacelle  12  and resting on a top side of a top portion  16  of the tower  11 . In  FIG.  1   , the components  14 ,  15  exemplary denominated inside the nacelle  12  are a main shaft  14  and a gearbox  15 . 
     A lifting platform  20  carrying the lifting device  30  is to be arranged underneath the nacelle  12  or main frame  13  or, in other words, on a bottom side of the nacelle  12 . For this purpose, the lifting platform  20  comprises two eyelets  26  for lifting the lifting platform  20  towards the nacelle  12 , where the lifting platform  20  may be attached to the bottom side of the nacelle  12 , i.e. to the main frame  13 . The lifting platform  20  may be attached to the main frame  13  by means of bolted joints, for example. 
     The lifting platform  20  comprises two beams  21 ,  22 . The beams  21 ,  22  are arranged parallel to one another and connected with each other by means of a carrying structure  24 . The carrying structure  23  has the two eyelets  26  on a top side thereof. Here, the carrying structure  23  is designed as a carrying plate. 
     Further, the carrying structure  23  comprises an attachment portion  25  for attachment to the main frame  13 . The attachment portion  25  is covered by the nacelle  12  when looked from the top and down to the nacelle  12  and the lifting platform  20 , as can be seen in  FIG.  2   . Also, the carrying structure  23  comprises a lifting device portion  24 , in which the lifting device  30  is installed. The lifting device  30  may be installed after lifting the lifting platform  20  first and consecutively lifting the lifting device  30  second, for example by means of an auxiliary lifting device (not shown) installed on the nacelle  12 . The auxiliary lifting device may be smaller in size and lighter in weight such that it may not be able to lift the heavy components  14 ,  15  of the wind turbine  10  but the lifting platform  20  and the lifting device  30 , which may be larger in size and heavier such that it may be able to lift the heavy components  14 ,  15  of the wind turbine  10 . When the lifting device  30  is lifted to the lifting platform  20 , the lifting device  30  is installed in the lifting device section  24  of the lifting platform  20 . 
       FIG.  2    shows a side perspective view on a wind turbine lifting arrangement  1  according to a first embodiment of the invention as installed according to  FIG.  1   . 
     Here, it can be seen that the lifting device  30  is installed on the lifting platform  20  such that the lifting device  30  is arranged next to a longitudinal side  19  of the nacelle  12 . The longitudinal side  19  is a side transverse, in particular perpendicular, to the top side  17  and/or bottom side  18  of the nacelle  12  and/or ground. The lifting platform  20  extends with its lifting device portion  24  from underneath the nacelle  12  along its longitudinal axis L 20  traverse to the nacelle  12 . In particular, an angle α is formed between the longitudinal axis L 20  of the lifting platform  20  and the longitudinal axis L 12  of the nacelle  12 . The angle α may be in the range of 80° to 100°, in particular 85° to 95°, for example. In this case, the angle α is 90° so that the lifting platform  20  is arranged perpendicular to the nacelle  12 . 
     In  FIG.  2   , the lifting device  30  is shown lifting a component  15  of the wind turbine  10 , in this case the gearbox  15 . This may be done for installing the gearbox  15  inside of the nacelle  12  or removing it therefrom for replacement or service. 
       FIG.  3    shows a side perspective view on a wind turbine lifting arrangement  1  according to a second embodiment of the invention. 
     According to this second embodiment, a support structure  27  is arranged underneath the lifting device  30 . The support structure  27  is designed as an elongate weighted body and extends along its longitudinal extension in parallel to an upper section of the tower  11 . The support structure  27  is arranged next to the tower  11  or in contact with the tower  11  such that it is pressed against the tower  11  when the lifting device  30  is loaded with a component  14 ,  15  of the wind turbine  10 . Thereby, the bending loads applied to the lifting platform  20  due to operation of the lifting device  30  are in part shifted to the support structure  27  transferring them to the tower  11 . 
     The support structure  27  has a concave side corresponding to and facing the rounded shape of the tower  11 . However, the concave side is covered by the support structure  27  in this perspective. 
       FIG.  4    shows a detailed side perspective view on the wind turbine lifting arrangement  1  of  FIG.  3    in operation of its lifting device  30 . Here, the lifting device  30  is lifting a component  14  of the wind turbine  1 , which may be the main shaft  14 . 
     Although the present invention has been disclosed in the form of embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention. 
     For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.