Abstract:
A transformer chamber for a wind turbine is described. The transformer chamber includes a liquid-tight tank for receiving a liquid-filled, in particular oil-filled, transformer, a wind turbine structure component includes a component bedframe adapted for receiving such a transformer chamber and a wind turbine includes such a transformer chamber and such a wind turbine structure component. Furthermore, a method for assembling a wind turbine is described.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority of European Patent Office application No. 11179874.0 EP filed Sep. 2, 2011. All of the applications are incorporated by reference herein in their entirety. 
       FIELD OF INVENTION 
       [0002]    The present disclosure relates to the field of wind turbines. In particular, the disclosure relates to a transformer chamber, a wind turbine structure component, a wind turbine, and a method for assembling a wind turbine. 
       BACKGROUND OF INVENTION 
       [0003]    Wind turbines becoming more and more popular for ecological power generation. 
         [0004]    Power generated by wind turbines has to be transformed to be transportable via high voltage transmission lines to the consumers. 
         [0005]    Liquid leaking from a liquid-filed transformer in case of a transformer failure may harm, in particular electrical and controlling, components near the liquid-filed transformer. 
       SUMMARY OF INVENTION 
       [0006]    There may be a need for a transformer chamber, a wind turbine structure component, a wind turbine, and a method for manufacturing a wind turbine reducing the risk associated with leaking liquid. 
         [0007]    This need may be met by the subject matter according to the independent claims Embodiments are described by the dependent claims. 
         [0008]    According to a first aspect, there is provided a transformer chamber for a wind turbine comprising a liquid-tight tank for receiving a liquid-filled, in particular oil-filled, transformer. This aspect is based on the idea that a second shell may limit the effect of transformer failures, as liquid originating from the transformer may be kept contained within the liquid-tight tank. 
         [0009]    Liquid-filled transformers are used as they may allow for better heat dissipation from coils and transformer sheets during operation of the transformer. In particular, insulating liquids may be used for liquid-filled transformers. These insulating liquids may help to avoid corona formation and arcing within the transformer. 
         [0010]    Some liquids like polychlorinated biphenyls may combine good insulating properties, i.e. a high dielectric strength, with good cooling properties. However, these liquids may be toxic. A transformer chamber with a liquid-tight tank may thus prevent that persons are exposed to these toxic substances. 
         [0011]    Transformer oil has also been found to combine good cooling properties and insulating properties. However, transformer oil may be less fire-resistant. The liquid-tight tank may prevent that leaking transformer oil reaches surfaces having a temperature above a flame point of the transformer oil. Hence, a transformer chamber with a liquid-tight tank may prevent inflammation of the transformer oil. 
         [0012]    The transformer chamber may comprise a pit, in particular an oil pit. The pit may allow collecting liquid, in particular transformer oil, during transformer chamber maintenance and reduce the amount of, e.g. toxic or burnable, substances within the transformer chamber. 
         [0013]    According to an embodiment of the transformer chamber for a wind turbine, the transformer chamber comprises a liquid-filled transformer with low voltage terminals and high voltage terminals, wherein the low voltage terminals and high voltage terminals are accessible from a top surface of the transformer chamber. 
         [0014]    This may reduce the time necessary for electrical installation of the transformer while at the same time maintaining the structural integrity of the liquid-tight tank. In particular, the transformer chamber may remain an essentially sealed tank such that no liquids may leak through the transformer chamber. 
         [0015]    According to another embodiment of the transformer chamber for a wind turbine, the transformer chamber comprises a damper, in particular a damper including hydraulic cylinders. Typically, transformers have a quite high mass, because they are essentially composed of huge amounts of copper and iron. Providing the transformer chamber for a wind turbine with a damper may reduce the oscillations associated with the transformer being arranged in at the top of a wind turbine. Thus, the load on the wind turbine tower may be reduced. 
         [0016]    According to yet another embodiment of the transformer chamber for a wind turbine, the liquid-tight tank is an explosion safe tank comprising an explosion plate, in particular an explosion plate made from aluminum. 
         [0017]    Gas may be produced during operation of the transformer, which gas may explode. If the liquid-tight tank is constructed so as to be an explosion safe tank comprising an explosion plate the risk to damage elements near the transformer in case of a transformer explosion may be limited. 
         [0018]    The explosion plate of the explosion tank may work as a predetermined breaking point. Thus, pressure due to the explosion may be released in a determined way. 
         [0019]    Aluminum may be in particular suitable because of its lower strength compared to steel, which may be the preferred material for the transformer chamber. 
         [0020]    According to a still further embodiment of the transformer chamber for a wind turbine, the transformer chamber comprises guiding elements, in particular wheels. 
         [0021]    These guiding elements may facilitate installation of the transformer chamber. Typically, the transformer chamber is installed at the top of the wind turbine, e.g. in the wind turbine nacelle or the wind turbine tower. The guiding elements, in particular wheels, may allow supporting the transformer chamber against the wind turbine tower either from the outside or form the inside when it is winched to the top. The exchangeability of the transformer chamber may likewise be improved. 
         [0022]    According to a second aspect there is provided a wind turbine structure component comprising a component bedframe adapted for receiving a transformer chamber. The component bedframe may allow a particularly easy fixing of the transformer chamber to the wind turbine structure component. 
         [0023]    According to a first embodiment of the wind turbine structure component, the wind turbine structure component comprises a cooling channel system. 
         [0024]    During operation heat has to be dissipated from the liquid-filled transformer. Providing the transformer chamber with a cooling channel system may allow for heat dissipation by convection that may be more efficient than heat dissipation by radiation and/or conduction. In particular, the cooling channels may be construed to guide air through fins of the liquid-filled transformer. Fins may augment the effective surface for heat dissipation. 
         [0025]    According to second embodiment the wind turbine structure component comprises a damper, in particular a hydraulic cylinder damper. 
         [0026]    Typically, transformers have a quite high mass, because they are essentially composed of huge amounts of copper and iron. Providing the wind turbine structure component with a damper may reduce the oscillations associated with the transformer being provided at the top of a wind turbine. Thus, the load on the wind turbine tower may be reduced. 
         [0027]    According to another embodiment of the wind turbine structure component is a wind turbine tower segment. 
         [0028]    If the wind turbine structure component is a wind turbine tower segment, the transformer chamber may be guided within the wind turbine tower during installation. Thus, installation of the transformer chamber may be performed in an environment protected from wind and rain. Furthermore, the transformer chamber may not be subjected to rotational forces when the wind turbine rotor is moved into the wind direction. 
         [0029]    According to a yet another embodiment of the wind turbine structure component is a wind turbine nacelle. 
         [0030]    The weight of the transformer may be beneficial when the wind turbine nacelle is adapted to receive the transformer chamber. The transformer may in this way be a counterweight to the wind turbine rotor. 
         [0031]    Placing the transformer chamber at the top of the wind turbine may help to reduce the cable length from the generator or converter to the transformer, in particular when the transformer chamber is provided within the wind turbine nacelle. 
         [0032]    According to a further embodiment the wind turbine structure component comprises a winch. 
         [0033]    The winch may render allow for installation of the wind turbine chamber without providing a crane. Thus, installation of the wind turbine chamber may be cheaper, in particular for offshore wind turbines. All means to install the transformer chamber may be provided on site. 
         [0034]    According to a still further embodiment the wind turbine structure component comprises a hatch. The hatch may allow moving the transformer chamber into the wind turbine structure 
         [0035]    According to another embodiment the wind turbine structure component comprises at least one cooling air inlet and at least one cooling air outlet adapted to provide the transformer chamber with cooling air. 
         [0036]    During operation heat has to be dissipated from the liquid-filled transformer and the transformer chamber. Providing the transformer chamber with at least one cooling air inlet and at least one cooling air outlet adapted to provide the transformer chamber with cooling air may allow using the wind driving the wind turbine rotor to be used for cooling. 
         [0037]    According to yet another embodiment the wind turbine structure component comprises a fan. A fan may augment the amount of air provided to the transformer chamber and/or other components of the wind turbine. Thus, even when there is a minimal wind, overheating of wind turbine components may be avoided. 
         [0038]    According to a third aspect there is provided a wind turbine comprising a transformer chamber as has been described hereinbefore and a wind turbine structure component, wherein the transformer chamber is detachably connected to the component bedframe. 
         [0039]    Such a wind turbine allows easy exchangeability of the transformer chamber and the transformer in case of a transformer failure. Furthermore, installation of the wind turbine, in particular at offshore location, may be simplified. 
         [0040]    According to an embodiment of the wind turbine the transformer chamber is movable, in particular in the direction of gravity, relative to the wind turbine structure component. 
         [0041]    Such a wind turbine may further facilitate the installation of the transformer chamber within the wind turbine structure component. A wind turbine nacelle may, for example, be provided with a hatch at the bottom such that the transformer chamber may be winched through the opened hatched. 
         [0042]    According to a forth aspect there is provided a method for assembling a wind turbine as has been described hereinbefore. 
         [0043]    The method may in particular be useful to erect and to overhaul a wind turbine. 
         [0044]    It has to be noted that embodiments have been described with reference to different subject matters. In particular, some embodiments have been described with reference to method type claims whereas other embodiments have been described with reference to apparatus type claims. However, a person skilled in the art will gather from the above and the following description that, unless other notified, in addition to any combination of features belonging to one type of subject matter also any combination between features relating to different subject matters, in particular between features of the method type claims and features of the apparatus type claims is considered as to be disclosed with this document. 
         [0045]    The aspects defined above and further aspects are apparent from the examples of embodiment to be described hereinafter and are explained with reference to the examples of embodiment. The embodiments will be described are in more detail hereinafter and are meant to be illustrative and not limiting. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0046]      FIG. 1  shows a transformer chamber in a perspective view. 
           [0047]      FIG. 2  shows a cutaway view of a transformer chamber. 
           [0048]      FIG. 3  shows another cutaway view of a transformer chamber. 
           [0049]      FIG. 4  shows yet another cutaway view of a transformer chamber. 
           [0050]      FIG. 5  shows a further cutaway view of a transformer chamber. 
           [0051]      FIG. 6  shows a still further cutaway view of a transformer chamber. 
           [0052]      FIG. 7  shows a cooling channel system of a transformer chamber. 
           [0053]      FIG. 8  shows a section of a wind turbine. 
           [0054]      FIG. 9  depicts a wind turbine nacelle. 
           [0055]      FIG. 10  shows a section of a wind turbine nacelle. 
           [0056]      FIG. 11  depicts a section of a wind turbine nacelle. 
           [0057]      FIG. 12  shows a transformer chamber 
           [0058]      FIG. 13  shows a transformer chamber 
           [0059]      FIG. 14  shows a section of a wind turbine nacelle. 
       
    
    
     DETAILED DESCRIPTION OF INVENTION 
       [0060]    The illustration in the drawing is schematically. 
         [0061]      FIG. 1  shows a transformer chamber  1  with an explosion safe tank  2  in a perspective view. The transformer chamber  1  surrounds an oil-filled transformer  3  only the top of which is visible. Air may flow through a first opening  4  into a cooling channel system of the transformer chamber  1 , where it may absorb heat generated by the oil-filled transformer  3 . The hot air may then leave the cooling channel system of the transformer chamber  1  through a second opening  5 . 
         [0062]    The bottom section of the transformer chamber  1  up to the height of the first opening  4  may be formed as an oil pit  6 . Leaking oil from a damaged oil-filled transformer, e.g. after an explosion of the oil-filled transformer, may be collected within the oil pit  6 . An explosion plate  7  made of aluminum may work as a predetermined breaking point and may reduce the damages in case of an explosion of the oil-filled transformer  3 . 
         [0063]    An upper side of the transformer chamber  1  is open and allows easy access to a high voltage terminal  8  and a low voltage terminal  9  of the oil-filled transformer  3 . This may allow a quick and easy replacement and reconnection of the oil-filled transformer  3  to electric wires. The top of the oil-filled transformer  3  further comprises transport rings  10 ,  11 , to which a hook or chain can be attached when an exchange of the oil-filled transformer  3  becomes necessary and the transformer chamber  1  with the oil-filled transformer therein needs to be lowered to or picked from surface level with a winch. 
         [0064]    The transformer chamber  1  further comprises two support rails  12 ,  13 , which may be used to attach the transformer chamber  1  to a bedframe of, e.g. a wind turbine nacelle. Two support beams  14  and  15  may enhance the rigidity of the transformer chamber  1 . 
         [0065]      FIG. 2  shows a cutaway view of a transformer chamber  16  with an explosion safe tank  17 . Like the transformer chamber  1  shown in  FIG. 1  the transformer chamber  16  comprises an oil-filled transformer  18 , a first opening  19 , a second opening  20 , an oil pit  21 , an explosion plate  22 , a high voltage terminal  23 , a low voltage terminal  24 , transport rings  25 ,  26 , support rails  27 ,  28 , and support beams  29 ,  30 . The features of this embodiment have been described with reference to  FIG. 1 . The oil-filled transformer  18  is placed in the transformer chamber  16  such that the distance between cooling fins  31  of the oil-filled transformer  18  and the wall of the transformer chamber  16  is kept very narrow. The narrow arrangement forces the air coming from the first opening along the cooling fins  31  for better cooling of the surfaces of the oil-filled transformer  18 . 
         [0066]      FIGS. 3 ,  4 ,  5  show further cutaway views of transformer chambers  32 ,  45 ,  58  with an explosion safe tank  33 ,  46 ,  59 . These transformer chambers  32 ,  45 ,  58  also include an oil-filled transformer  34 ,  47  a first opening, a second opening  35 ,  48  an oil pit, an explosion plate, a high voltage terminal  36 ,  49 ,  60  a low voltage terminal  37 ,  50 ,  61  transport rings  38 ,  39 ,  51 ,  52 ,  62 ,  63  support rails  40 ,  41 ,  53 ,  54 ,  64 ,  65 , support beams  42 ,  43 ,  55 ,  56 ,  66 ,  67 , and cooling fins  44 ,  57  comparable to those as have been described hereinbefore. 
         [0067]      FIG. 6  shows a still further cutaway view of a transformer chamber  68  focusing on its explosion plate  69  above its first opening  70 . The explosion plate  69  is made from aluminum and represents a predetermined breaking point, which bursts in case of an explosion and allows release of pressure at a secure location avoiding unpredictable and harmful damage to the transformer chamber  68  and its features. The explosion plate is fixed to the transformer chamber  68  with seven bolts  71 ,  72 ,  73 ,  74 ,  75 ,  76 ,  77  of which five bolts  71 ,  72 ,  73 ,  74 ,  75  are located along a bottom portion parallel to the first opening  70 . A bending section of the explosion plate is created with slits  78  running parallel to the first opening  70 . Two deformation bolts  76 ,  77  hold the explosion plate  69  to the transformer chamber  68  on an upper section of the explosion plate  69 . In case of an explosion these two bolts  76 ,  77  and the explosion plate  69  bends outwardly along the bending section. The bending section works similar to a hinge. 
         [0068]      FIG. 7  shows a cooling channel system  79  for a transformer chamber. Two inlet interfaces  80 ,  81  may be connected to transformer chamber&#39;s first openings. One outlet interface  82  may be joinable to a second opening of a transformer chamber. A fan may be located behind the outlet interface and create a cooling airflow by sucking in ambient air. This air may then be fed into the transformer chamber through the two inlet interfaces  80 ,  81  and be received by the outlet interface  82  before it is blown out through the channel outlet  83  of the cooling channel system  79 . 
         [0069]      FIG. 8  shows a section of a wind turbine  84  comprising a wind turbine tower  85 . A person  86  is depicted to give an indication of the size of the wind turbine  84 . A wind turbine nacelle  87  is mounted to the top of the wind turbine tower  85 . The outer walls of the wind turbine nacelle  87  are not shown. The wind turbine nacelle  87  comprises a support structure and a component bedframe  88 , which is bolted to the support structure. However, the component bedframe  88  and the support structure may in an alternative embodiment also be made in one piece. 
         [0070]    The support structure is rotatable connected to the wind turbine tower  85  and supports a generator  89  with a wind turbine rotor  90  connected thereto. The wind turbine rotor  90  comprises a hub  91  and blades  92 . 
         [0071]    The component bedframe  88  and the support structure carry inter alia electrical components  93  such as a converter, communication units and control units. A transformer chamber  94  holding an oil-filled transformer is mounted to the bottom side of the component bedframe  88  in close vicinity to the wind turbine tower  85 . The center of mass is located close to the wind turbine tower  85  by positioning the heavy oil-filled transformer close to the wind turbine tower  85 . Thus, structural loads on the wind turbine  84 , in particular on the wind turbine tower  85 , the support structure and the component bedframe  88 , may be minimized. 
         [0072]    Furthermore, by placing the transformer chamber  94  on the opposite side of the wind turbine rotor  90  the weight of the transformer chamber  94  comprising the oil-filled transformer may counteract the weight of the wind turbine rotor  90 . This may additionally reduce structural loads. 
         [0073]    The transformer chamber  94  comprises guiding in elements in form of wheels. These wheels may allow an easy movement of the transformer chamber  94  relative to the wind turbine tower  85 , which may be used as guidance when the transformer chamber  94  is lowered to the surface or raised therefrom. Guiding the transformer chamber  94  may reduce the security risks associated with swinging masses. 
         [0074]    The wind turbine nacelle  87  may additionally comprise a winch with a chain or rope, which is attachable to the transformer chamber  94 . This may allow exchanging the transformer chamber  94  without the need of additional cranes. 
         [0075]      FIG. 9  depicts a wind turbine nacelle  95  mounted to the top of a wind turbine tower  96 . A transformer chamber  97  comprising an explosion safe tank  98  is bolted to a component bedframe  99 . A ladder  100  provides ease of access to the transformer chamber  97  and to electrical components  101  from the support structure. The ladder  100  and the placement of the transformer chamber  97  with the transformer therein inside the canopy of the wind turbine nacelle  95  may allow repair work and service to be done even under adverse weather conditions. 
         [0076]      FIG. 10  shows a section of a wind turbine nacelle  102  in a cutaway view. The wind turbine nacelle  102  houses a transformer chamber  103  with an explosion safe tank. The transformer chamber  103  comprises an oil-filled transformer  104  and is attached to a component bedframe of the wind turbine nacelle  102 . A hatch  105  is provided such that the transformer chamber  103  may easily be lowered from the wind turbine nacelle  102  to the surface. The wind turbine nacelle  102  further houses electric components  106 , e.g. a converter, communication units and control units, which may be arranged in cabinets on a support structure of the wind turbine nacelle  102 . The access to the transformer chamber  103  and to the electric components  106  may be facilitated by means of a ladder  107 . The wind turbine nacelle  102  further comprises a cooling channel system  108  for the transformer chamber  103 . Fans  109  blow ambient air into the cooling channel system  108  and the transformer chamber  103 , where it serves to dissipate from the oil-filled transformer  104 . The hot air then is guided by the cooling channel system  108  to the channel outlet  110  where it is released to the outside of the wind turbine nacelle  102 . 
         [0077]      FIG. 11  depicts a section of a wind turbine nacelle  111  housing a transformer chamber  112 . Only parts of the transformer chamber  112  are shown. A transformer (not shown) rests on two pads  113 ,  114  of the transformer chamber  112 . The pads  113 ,  114  may be made of a resilient material and absorb the vibrations associated with the frequency of the power grid. The material may in particular be adapted to absorb vibrations with a frequency of 50 Hertz or 60 Hertz. A support beam  115  is provided to augment the rigidity of the transformer chamber  112 . The transformer chamber  112  is attached to the component bedframe of the wind turbine nacelle  111  with two support rails  116 ,  117  such that in case of an explosion of the transformer an explosion plate  118  of the transformer chamber  112  may work as a predetermined breaking point and the pressure may be released in a direction laterally of the wind turbine nacelle  111 . Thus, harmful damages to other components within the wind turbine nacelle  111  may be avoided or at least reduced. A wind turbine tower  119  supports the wind turbine nacelle  111  and a cable  120  transmits the power generated from a high voltage terminal of the oil-filled transformer along the inside of the wind turbine tower  119  to the main power grid. 
         [0078]      FIGS. 12 and 13  show a transformer chamber  120 . The transformer chamber  120 ,  128  comprises L-shaped support rails  121 ,  122 ,  129 . With these L-shaped support rails  121 ,  122 ,  129  the transformer chamber  120 ,  128  is bolted at four corners  123 ,  124 ,  125  to a component bedframe  126  of a wind turbine nacelle  127 . The transformer  130  is bolted to the top  131  and the bottom  132  of the transformer chamber  128 . 
         [0079]      FIG. 14  shows a section of a wind turbine nacelle  133  at the top of a wind turbine tower  134 . The wind turbine nacelle  133  comprises an inlet  135  for sucking in ambient air for cooling of components within the wind turbine nacelle  133  and an outlet  136  for blowing out hot air. 
         [0080]    While specific embodiments have been described in detail, those with ordinary skill in the art will appreciate that various modifications and alternative to those details could be developed in light of the overall teachings of the disclosure. For example, elements described in association with different embodiments may be combined. Accordingly, the particular arrangements disclosed are meant to be illustrative only and should not be construed as limiting the scope of the claims or disclosure, which are to be given the full breadth of the appended claims, and any and all equivalents thereof. It should be noted that the term “comprising” does not exclude other elements or steps and the use of articles “a” or “an” does not exclude a plurality.