Abstract:
A method of assembling and/or disassembling a rotating electric machine of a wind turbine having a vertical structure; a main frame fitted to the top of the vertical structure; a blade assembly fitted to the main frame to rotate about a rotation axis; and a tubular rotating electric machine having a plurality of axial active segments; the method including inserting and/or extracting the active segments axially on the blade assembly side.

Description:
PRIORITY CLAIM 
       [0001]    This application is a national stage application of PCT/IB2014/059315, filed on Feb. 27, 2014, which claims the benefit of and priority to Italian Patent Application No. MI2013A 000288, filed on Feb. 27, 2013, the entire contents of which are each incorporated by reference herein. 
     
    
     BACKGROUND 
       [0002]    Wind turbines for generating electric power normally comprise a vertical support; a main frame which rotates about a vertical axis with respect to the vertical support; a blade assembly, which comprises a hub and at least two blades fitted to the hub, and is connected to the main frame by at least one bearing to enable the blade assembly to rotate about a rotation axis; and a rotating electric machine rotated by the blade assembly and comprising a stator connected to the main frame, and a rotor connected to the blade assembly. The stator and rotor normally comprise respective tubular active parts facing each other and separated by an air gap. 
         [0003]    The blade assembly on direct-drive wind turbines is connected rigidly to the rotor, and the bearing supports both the rotor and the blade assembly for rotation about the rotation axis. On direct-drive wind turbines, it is a fairly common practice to employ one bearing to absorb radial and axial forces and tipping moments. Whereas other wind turbine configurations employ two coaxial bearings. Each active part is usually divided into active segments fitted to a respective tubular structure and extending predominantly axially with respect to the rotation axis of the rotating electric machine. 
         [0004]    Installing the wind turbine and servicing the rotating electric machine both involve assembling and/or disassembling the active segments of the rotating electric machine in a position that makes it relatively difficult to insert and/or extract and handle the active segments. 
       SUMMARY 
       [0005]    The present disclosure relates to a method of assembling and/or disassembling a wind turbine rotating electric machine. 
         [0006]    More specifically, the present disclosure relates to a method of assembling and/or disassembling active parts of a rotating electric machine fitted to the top of a wind turbine. 
         [0007]    It is an advantage of the present disclosure to provide a relatively simple, relatively fast, and relatively efficient method of assembling and/or disassembling a wind turbine rotating electric machine. 
         [0008]    According to the present disclosure, there is provided a method of assembling and/or disassembling a wind turbine rotating electric machine, the wind turbine comprising a vertical structure; a main frame fitted to the top of the vertical structure; a blade assembly fitted to the main frame to rotate about a rotation axis; and a tubular rotating electric machine comprising a plurality of axial active segments; the method comprising the step of inserting and/or extracting the active segments axially on the blade assembly side. This way, the rotating electric machine can be assembled and/or disassembled with none of the geometric constraints that impair speed and efficiency when inserting and/or extracting the active segments on the main frame side. 
         [0009]    In certain embodiments, the method comprises connecting an insertion and extraction device to the blade assembly; and selectively positioning the insertion and extraction device close to one of the active segments by rotating the blade assembly. This way, the insertion and extraction device can be aligned selectively with an active segment for extraction, or with a seat in which to insert an active segment, by simply rotating the blade assembly. 
         [0010]    In certain embodiments, the method comprises hoisting the insertion and extraction device. This way, the insertion and extraction device is assembled when needed. 
         [0011]    In certain embodiments of the present disclosure, the method comprises hoisting the insertion and extraction device using a hoisting device, which is mounted on the wind turbine, extends through the wind turbine, and, in certain such embodiments, comprises a winch fixed to the wind turbine, and a cable extending through the rotating electric machine and the blade assembly. This way, the insertion and extraction device can simply be hoisted into a precise position along the blade assembly. 
         [0012]    In certain embodiments, the method comprises the step of fixing a safety cell, configured to accommodate an operator, to the blade assembly; said insertion and extraction device being housed inside the safety cell. This enables the operator to work in the relatively utmost safety. And moreover, positioning the safety cell automatically positions the insertion and extraction device. 
         [0013]    In certain embodiments, the method comprises the step of positioning the safety cell so that a first opening in the blade assembly is located at a second opening in the safety cell. In certain such embodiments, the first and second opening being configured to permit passage of an operator or objects. 
         [0014]    The first opening mainly serves to run the winch cable out of the hub, for connection to the safety cell. 
         [0015]    The second opening creates contiguity between the hub and the safety cell. 
         [0016]    In certain embodiments of the present disclosure, the safety cell is cylindrical. This enables the operator an optimal stance in which to work, regardless of the angular position of the safety cell about the rotation axis. 
         [0017]    In certain embodiments, the method comprises adjusting the radial distance of the insertion and extraction device with respect to the rotation axis. In other words, the insertion and extraction device is positioned using a system of polar coordinates about the rotation axis. 
         [0018]    A further advantage of the present disclosure is to provide a relatively fast, and relatively efficient system of assembling and/or disassembling a wind turbine rotating electric machine. 
         [0019]    According to the present disclosure, there is provided a system configured to assemble and/or disassemble a wind turbine rotating electric machine, the wind turbine comprising a vertical structure; a main frame fitted to the top of the vertical structure; a blade assembly fitted to the main frame to rotate about a rotation axis; and a tubular rotating electric machine comprising active segments; the system comprising an insertion and extraction device configured to insert and/or extract active segments axially on the blade assembly side. This eliminates certain of the physical and geometric constraints resulting in relatively cramped working conditions when inserting and/or extracting the active segments on the main frame side. 
         [0020]    In certain embodiments of the present disclosure, the system comprises a connecting device configured to connect the insertion and extraction device to the blade assembly so as to selectively position the insertion and extraction device close to one of the active segments by rotating the blade assembly. This connection enables the blade assembly to be used as a positioning device to position the insertion and extraction device. 
         [0021]    In certain embodiments, the system comprises a safety cell configured to fit to the blade assembly and to accommodate an operator; said insertion and extraction device being housed inside the safety cell. This enables the operator to operate the insertion and extraction device in the relatively utmost safety. 
         [0022]    In certain embodiments, the safety cell is cylindrical and comprises at least one circular guide. 
         [0023]    The circular guide serves to guide the insertion and extraction device. 
         [0024]    More specifically, the system comprises a store configured to house active segments and movable along the circular guide. 
         [0025]    The safety cell provides a structure by which to support accessory structures configured to relatively simplify and relatively speed up assembly and/or disassembly work. 
         [0026]    In certain embodiments, the system comprises a service winch movable selectively along the circular guide. This way, active segments can be loaded into and unloaded from the safety cell without having to lower the safety cell. 
         [0027]    In certain embodiments, the system comprises a manipulator configured to manipulate the active segments; the manipulator being movable selectively along the circular guide. 
         [0028]    The active segments may be relatively extremely heavy, and must therefore be handled using suitable tools inside the safety cell. 
         [0029]    Additional features and advantages are described in, and will be apparent from the following Detailed Description and the figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    A non-limiting embodiment of the present disclosure will be described by way of example with reference to the attached drawings, in which: 
           [0031]      FIG. 1  shows a longitudinal section, with parts removed for clarity, of a system configured to assemble and/or disassemble a wind turbine rotating electric machine in accordance with the present disclosure; 
           [0032]      FIG. 2  shows a larger-scale elevation, with parts removed for clarity, of the  FIG. 1  system; 
           [0033]      FIG. 3  shows a larger-scale view in perspective, with parts removed for clarity, of one operating stage of the  FIG. 1  system; and 
           [0034]      FIGS. 4 and 5  show larger-scale elevations, with parts removed for clarity, of further operating stages of the  FIG. 1  system. 
       
    
    
     DETAILED DESCRIPTION 
       [0035]    Referring now to the example embodiments of the present disclosure illustrated in  FIGS. 1 to 5 , number  1  in  FIG. 1  indicates as a whole a wind turbine configured to generate electric power. Wind turbine  1  is a direct-drive type and, in the example shown, comprises a vertical support  2 ; a main frame  3 ; a rotating electric machine  4 ; and a blade assembly  5  which rotates about a rotation axis A. Rotating electric machine  4  is located between main frame  3  and blade assembly  5 , and, in addition to producing electric power, provides for supporting blade assembly  5 , and for transmitting forces and moments induced by blade assembly  5  and rotating electric machine  4  to main frame  3 . 
         [0036]    In the example shown, main frame  3  is defined by a curved, tubular nacelle  6 , which comprises a circular end flange  7  for connection to rotating electric machine  4 ; an end flange  8  configured to house a pivot  9  for connection to vertical support  2 ; and an opening  10  such as an opening substantially aligned with end flange  8 . 
         [0037]    Blade assembly  5  comprises a hub  11  connected to rotating electric machine  4 ; and a plurality of blades  12  ( FIG. 2 ). Hub  11  comprises a hollow member  13  configured to support blades  12  ( FIG. 2 ); and a flange  14  for connection to rotating electric machine  4 . 
         [0038]    Rotating electric machine  4  extends about rotation axis A, and is substantially tubular, so as to form a passage between the hollow main frame  3  and the hollow hub  11 . 
         [0039]    Rotating electric machine  4  comprises a stator  15 ; a rotor  16 , which is located inside stator  15  and rotates about rotation axis A with respect to stator  15 ; and a frame  17  configured to connect rotating electric machine  4  to main frame  3 , and configured to support blade assembly  5 , stator  15 , and rotor  16 . 
         [0040]    Frame  17  extends about rotation axis A, and comprises a tubular structure  18  having a cylindrical face  19  and configured to support a tubular active part  20  along cylindrical face  19 ; an annular flange  21  configured to connect rotating electric machine  4  to main frame  3  of wind turbine  1 ; and a ring  22  having an annular seat  23  configured to at least partly house a bearing  24 . In the example shown, one bearing  24  supports both blade assembly  5  and rotor  16  integral with blade assembly  5 . In other words, because tubular structure  18  forms part of tubular stator  15 , frame  17  also defines part of tubular stator  15 , which comprises tubular structure  18  and active part  20 . 
         [0041]    Tubular active part  20  is divided into a plurality of axial active segments  25 , each of which, in the example shown, has electric windings supported of a substantially prismatic ferromagnetic core extending predominantly parallel to axis of rotation A. 
         [0042]    In certain embodiments, active segments  25  are fitted to the structure by respective prismatic joints, so as to slide axially. 
         [0043]    In certain embodiments, frame  17  and main frame  3  are connected by a bolted connection (not shown in the drawings) between annular flange  21  and end flange  8 , and by which the forces and moments induced by rotating electric machine  4  and blade assembly  5  are transmitted to main frame  3 . 
         [0044]    In certain embodiments, rotating electric machine  4 , (i.e., wind turbine  1 ), only has bearing  24  to support the radial and axial loads transmitted from tubular rotor  16  and blade assembly  5  to main frame  3 . 
         [0045]    Tubular rotor  16  comprises a tubular structure  26  having a cylindrical face  27 ; a tubular active part  28 ; and a radial structure  29  located inside tubular structure  26  and connected to bearing  24 . In other words, radial structure  29  is fixed to bearing  24  on one side, and to hub  11 —more specifically, to flange  14  of hub  11 —on the opposite side. 
         [0046]    Like active part  20 , active part  28  comprises axial active segments  30 , each of which, in the example shown, has permanent magnets fitted to respective magnetic guides, is prismatic in shape, and extends predominantly parallel to rotation axis A. In other words, rotating electric machine  4  is tubular, and communicates directly with hollow hub  11 . 
         [0047]    Dimensionally, active parts  20  and  28  have a minimum diameter larger than the maximum diameter of hub  11 . And wind turbine  1  has a front casing  31 , which, as shown in  FIG. 1 , has openings  32  by which to insert and remove active segments  25  and  30  on the hub  11  side. Alternatively, the casing may be removed completely or partly. 
         [0048]    Generally speaking, wind turbine  1  as a whole is configured to permit insertion and removal of active segments  25  and  30  on the hub  11  side. 
         [0049]    In  FIG. 1 , wind turbine  1  is connected to a system  33  by which to insert and/or extract active segments  25  and  30  of rotating electric machine  4  on the hub  11  side. 
         [0050]    System  33  comprises a hoisting device  34 ; an insertion and extraction device  35  configured to insert and/or extract active segments  25  and/or  30  axially into/from rotating electric machine  4 ; and a connecting device  36  configured to connect insertion and extraction device  35  to blade assembly  5 —more specifically, to hub  11 . 
         [0051]    In certain embodiments, connecting device  36  comprises a safety cell  37  configured to house at least one operator and a plurality of active segments  25  and/or  30 , as shown more clearly in  FIG. 2 . 
         [0052]    As shown in  FIG. 1 , safety cell  37  is cylindrical, and, in certain embodiments, comprises two circular guides  38  connected by a supporting structure  39 . Safety cell  37  comprises two grille type curtain walls  40 , one of which is configured to face rotating electric machine  4 , and has an opening  41  by which to insert and/or extract active segments  25  and/or  30  ( FIG. 1 ). 
         [0053]    Safety cell  37  is configured to fix rigidly to blade assembly  5 . More specifically, safety cell  37  is configured to fix to hub  11 , and, in certain embodiments, comprises a connecting member  42  located along supporting structure  39 , and which cooperates with a connecting member  43  located along hub  11 , between two adjacent blades  12 . 
         [0054]    In certain embodiments, hub  11  and connecting member  42  have respective openings  44  and  45  to permit direct communication between hollow hub  11  and safety cell  37 . 
         [0055]    In the case of a relatively very large hub  11 , openings  44  and  45  may even be formed to enable passage of the operator from hub  11  to safety cell  37  and vice versa. 
         [0056]    As shown in  FIG. 2 , insertion and extraction device  35  is fixed to safety cell  37  with only relatively small radial adjustments enabled. 
         [0057]    Safety cell  37  also supports a store  46  for active segments  25  and/or  30 ; a service winch  47 ; and a manipulator  48  configured to handle active segments  25  and/or  30  between insertion and extraction device  35  and store  46 . 
         [0058]    As shown in  FIGS. 2 to 5 , in certain embodiments, store  46 , service winch  47 , and manipulator  48  are mounted to run along at least one of guides  38  into different operating positions, depending on the position of, and the work to be carried out in, safety cell  37 . 
         [0059]    As shown in  FIG. 1 , hoisting device  34  comprises a winch  49  fitted to main frame  3 ; a cable  50  of winch  49 , connectable to safety cell  37 ; and guide pulleys  51  configured to route cable  50  through rotating electric machine  4 , hub  11 , and opening  44 . 
         [0060]    In actual use, and as shown in  FIG. 3 , safety cell  37  and insertion and extraction device  35  are hoisted off the ground by hoisting device  34 , and, once the assembly and/or disassembly work on wind turbine  1  is completed, are lowered back down to the ground and stowed. 
         [0061]    On reaching hub  11 , insertion and extraction device  35  is fixed to blade assembly  5 —in the example shown, to hub  11 —as shown in  FIG. 2 , in which the insertion and extraction device is set to the six o′clock position. By rotating blade assembly  5  about rotation axis A, insertion and extraction device  35  can be aligned with any one of active segments  25 .  FIGS. 4 and 5  show insertion and extraction device  35  in the four o&#39;clock and twelve o&#39;clock positions respectively. 
         [0062]    With reference to  FIG. 1 , the operator assigned to insert and/or extract active segments  25  travels to the work station at hub  11  inside safety cell  37 , or, if openings  44  and  45  are large enough, accesses the safety cell from wind turbine  1 . 
         [0063]    The cylindrical shape of safety cell  37  enables the operator an optimal working position, regardless of the angular position of safety cell  37  about rotation axis A. 
         [0064]    Clearly, changes may be made to the method and system according to the present disclosure without, however, departing from the protective scope of the accompanying Claims. That is, various changes and modifications to the presently disclosed embodiments will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.