Abstract:
An apparatus for enabling transmission of signals and data via means of infrared (IR) light for a wind turbine includes a plurality of IR data communication elements configured to provide unidirectional and bidirectional IR data exchange between non-rotating portions of the wind turbine and the rotatable wind turbine hub.

Description:
BACKGROUND 
       [0001]    This invention relates generally to wind turbines, and more particularly to methods and apparatus for enabling transmission of data and signals between non-rotating portions of a wind turbine nacelle and a rotating hub. 
         [0002]    A conventional slipring is generally used to transmit discrete low voltage signals and to accommodate communication bus protocols between the stationary and rotational parts of a wind turbine. Sliprings are also used to transfer AC or DC power. Sliprings are based on a physical connection between the stationary and rotary structures, accomplished through electrically conductive sliding elements that are subject to wear-out, limiting the design life and reliability of the sliprings. 
         [0003]    Other techniques for enabling transmission of data between non-rotating portions of a wind turbine nacelle and a rotating hub may include use of fiber optic rotary joints, or use of wireless transmission, GSM mobile transmission, inductive coupling(s), or capacitive coupling(s). 
         [0004]    It would be advantageous to provide methods and apparatus for enabling transmission of data and signals between non-rotating portions of a wind turbine nacelle and the rotating hub that are less expensive to manufacture or otherwise employ while achieving equal or greater reliability than methods and apparatus that require the use of fiber optic rotary joints, wireless transmission, GSM mobile transmission, inductive coupling(s), or capacitive coupling(s). 
       BRIEF DESCRIPTION 
       [0005]    According to one embodiment, an apparatus for enabling transmission of signals and data via a means of infrared (IR) light for a wind turbine comprises a plurality of IR data communication elements configured to provide unidirectional or bidirectional IR data and signal exchange between a non-rotating portion of a wind turbine and a rotatable wind turbine hub in response to rotation of a rotating portion of the wind turbine. 
     
    
     
       DRAWINGS 
         [0006]    These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
           [0007]      FIG. 1  illustrates a wind turbine in which embodiments of the invention are integrated therein; 
           [0008]      FIG. 2  is a simplified block diagram illustrating components in a wind turbine nacelle and hub for power and data communication systems in which embodiments of the invention are integrated therein; and 
           [0009]      FIG. 3  illustrates a more detailed view of the rotary joint portion of the wind turbine signal and data communication system depicted in  FIG. 2 , showing infrared (IR) data communication elements according to one embodiment. 
       
    
    
       [0010]    While the above-identified drawing figures set forth alternative embodiments, other embodiments of the present invention are also contemplated, as noted in the discussion. In all cases, this disclosure presents illustrated embodiments of the present invention by way of representation and not limitation. Numerous other modifications and embodiments can be devised by those skilled in the art which fall within the scope and spirit of the principles of this invention. 
       DETAILED DESCRIPTION 
       [0011]    In some configurations and referring to  FIG. 1 , a wind turbine  10  comprises a nacelle  11  housing a generator. Nacelle  11  is mounted atop a tall tower  12 . Wind turbine  10  also comprises a rotor that includes one or more rotor blades  14 ,  15 ,  16  attached to a rotating hub  18 . Although wind turbine  10  illustrated in  FIG. 1  includes three rotor blades  14 ,  15 ,  16 , there are no specific limits on the number of rotor blades required by the embodiments described herein. 
         [0012]    In some configurations, various components are housed in nacelle  11  atop tower  12  of wind turbine  10 . The height of tower  12  is selected based upon factors and conditions known in the art. In some configurations, one or more controllers including algorithmic software are used for wind-speed monitoring and turbine control and may be based on distributed or centralized control architectures. 
         [0013]    In some configurations, one or more variable blade pitch drive actuators are provided to control the pitch of blades  14 ,  15 ,  16 . In some configurations, the pitches of blades  14 ,  15 ,  16  are individually controlled by the blade pitch actuators. 
         [0014]    The drive train of the wind turbine includes a main rotor shaft (also referred to as a “low speed shaft”) connected to the hub  18  via a main bearing and (in some configurations), at an opposite end of the rotor shaft to a gear box enumerated  22  in  FIG. 2 . The gear box  22 , in some configurations, utilizes dual path geometry to drive an enclosed high speed shaft. In other configurations, the main rotor shaft is coupled directly to a generator. The high speed shaft is used to drive the generator. 
         [0015]      FIG. 2  illustrates a wind turbine data communication system  20  in which embodiments of the invention described below with reference to  FIG. 3 , are integrated therein. A pitch tube  24  is configured to rotate in coordination with the rotor hub  18  that rotates in response to wind contacting the rotor blades  14 - 16 . The pitch tube  24  can be seen to pass through a gearbox  22  on its way to one or more rotary joints  40  that include a data or signal rotary joint  41  and a power rotary joint  42 . The embodiments described herein relate only to data or signal transmission via means of infrared light and not to power transmission, and so apply only to the data or signal rotary joint portion of the rotary joints  40 . The data/signal rotary joint  41  is configured to assist communication of data and signals between the rotor hub  18  and a topbox  28  that includes one or more low voltage data communication buses  30 . Electrical power is transmitted via one or more power supply buses  32  while data communication signals are transmitted via one or more low voltage data communication buses  30 . 
         [0016]    More specifically, the pitch tube  24  is fixed to the hub  18 , and the hub  18  is being rotated by the wind turbine blades  14 ,  15 ,  16 , which are fixed to the hub  18 . Pitch tube  24  is a commonly used term in wind industry for the pipe which guides the electrical cables from the hub  18  through the gearbox  22 , where finally the slipring (or rotary joint(s))  40  is mounted. The apparatus may or may not be connected to a pitch tube  24 , and alternatively it is connected with the main shaft, or even directly with the hub  18 . Important is only, that it is connected with a rotating element being part of the so-called hub  18  and being rotated with the same speed as the hub  18 . 
         [0017]      FIG. 3  illustrates a more detailed view of the data/signal rotary joint portion  41  of the wind turbine data communication system  20  depicted in  FIG. 2 , and shows infrared (IR) data communication elements  56 ,  60 ,  62 ,  64 ,  66  according to one embodiment. More specifically, embodied rotary joint portion  41  includes a stationary section  50  where the data/signal bus  30  from the topbox  28  is connected. Rotary joint portion  41  further includes a rotating section  52  that is fixed to the rotatable pitch tube  24  via a flange  54 . The present invention is not so limited however, and it can be appreciated that the IR joint does not necessarily need to be attached to the rotary power transmission element. The IR joint could, for example, be directly coupled to the pitch tube, in which case the rotary power transmission element(s) will be disposed behind the IR joint; or the IR joint could be coupled to the rotary power transmission element(s). 
         [0018]    Rotary joint portion  41  includes a transmitter IR diode  56  disposed on the central axis  58  of rotating section  52 . At least one receiver IR diode  60  is disposed near an outer periphery of rotating section  52 . Embodied stationary section  50  includes a receiver diode  62  disposed on the central axis  58  of the rotating section and configured to receive IR data signals transmitted via transmitter IR diode  56 . One or more transmitter diodes  64 ,  66  are also disposed on stationary section  50 . Each stationary section transmitter diode  64 ,  66  is configured to transmit a data IR signal in the direction of a corresponding signal transmission axis  68 ,  70 . Each rotating section receiver IR diode  60  is configured to receive the IR data signals transmitted via the stationary section transmitter diodes  64 ,  66  along the corresponding signal transmission axes  68 ,  70 . In this manner, bi-directional IR data transmission and reception takes place between the stationary section(s)  50  that forms a non-rotating portion of a wind turbine nacelle  11  according to one embodiment and a rotatable wind turbine hub  18  or corresponding pitch tube  24 . 
         [0019]    In summary explanation, an apparatus and method have been described for transmission of data between the non-rotating part of a wind turbine nacelle  11  and a rotating hub  18 . The data transmission is achieved via infrared light, such as set forth according to well known communication standard IrDA-1.1. Standard components for infrared light emission and detection can be utilized for data transmission in wind turbines, where slip rings are conventionally used to achieve data transmission. The IR data transmission is achieved at the back end of the pitch tube  24  according to one embodiment so that at least one IR transmitter  56  and corresponding receiver  62  can be axially aligned with the central axis  58  of the pitch tube  24 . Infrared diodes  64 ,  66 ,  60  are placed on a similar radius around the rotating axis  58 , so that the diodes can see one another. These IR diodes radiate light with a certain opening angle of radiation, and there can be several diodes across the corresponding circumference, so rotation changes the corresponding diode communication with respect to time. Some misalignment or angular displacement between IR diodes  66  and  60  can be tolerated while achieving the desired data or signal transmission. The pitch tube  24  rotates with the rotor and hub  18  of the wind turbine  10  and provides a means for providing the hub  18  with electrical power and data communication signals. The continuous communication between a master controller unit  82  (PLC located inside the top box  28 ) and a slave unit pitch controller (typically located inside the hub  18 ) runs over a bi-direction and full-duplex network. 
         [0020]    The use of IR technology provides a lower cost communication network with high reliability when compared to conventional slip rings. Further, this IR technology is simpler in structure to implement compared to glass fiber rotary joints, wireless transmission, GSM mobile transmission, inductive coupling and capacitive coupling techniques. Further, the IR technology advantageously protects the data communication link from damaging emi/emc effects. 
         [0021]    According to one embodiment, at least one IR data communication element  56 ,  60 ,  62 ,  64 ,  66  comprises a single or multi-wavelength IR device such as, without limitation, an IR diode that is configured to allow passage of IR data signals through predetermined device surface contaminants. Such contaminants may include, without limitation, fog, smoke, snow and even dirt and/or dust. At least one IR data communication element may be configured with a super-hydrophobic coating to protect a predetermined IR device from foul weather elements such as icing and/or rain. The lens or optical aperture of one or more of the IR data communication elements may be enhanced to provide a harsher operating environment tolerant element and may be configured to better collimate the IR emission of an IR device such as an IR diode, or to focus a narrow spot size on a targeted area. 
         [0022]    At least one IR data communication element  56 ,  60 ,  62 ,  64 ,  66  according to another embodiment comprises a single or multi-wavelength IR device configured with an active surface heater  72  to remove moisture from optical surfaces. The IR data communication element may further include independently or in addition to the active surface heater, a rotating surface wiper  74  to provide a dusting effect on occasional or a regular rotational schedule. A shroud can independently or additionally be added to ingress points (enumerated  76  in  FIG. 2 ) in the pitch tube  24  to prevent solar blinding IR effects. Other embodiments may employ one or more single or multi-wavelength IR devices configured with a lens surface area to substantially fit the pitch tube signal area. 
         [0023]    According to one embodiment, the apparatus further comprises an adaptive IR link power budget monitor/controller  80  such as depicted in  FIG. 2  that is configured to control IR data signal power in response to predetermined IR data communication element conditions. These conditions include, without limitation, surface contaminant build-up, miss-alignment, device wear, elastomer mount wearout, and vibration. 
         [0024]    According to one embodiment, rotary joint portion  41  includes microelectronics  80  integrated therein to control and enable usage of the IR diodes  56 ,  60 ,  62 ,  64 ,  66 . The electronics is preferably located on the same circuit board as the IR diodes. Multiple functions can be achieved with the electronics, such as data integrity check via means of additional data protocols, adaptation to different bus interfaces (such as Ethernet, CANbus, USB), adaptation to different bus data rates, control of power consumption as mentioned above, or it could as well measure rotational speed. One basic function of the electronics  80  is to configure the electrical bus signal such that each diode produces suitable light pulses, and on the receiver side to amplify the signals and re-convert into suitable bus signals. 
         [0025]    Infrared light as used in this application shall be understood to mean electromagnetic waves with wavelength in the range of 780 nm to 1 mm. The IR light may or may not be coherent light, as produced by laser light diodes commonly used for fiber optic cables or fiber optic rotary joints. One typical embodiment of the apparatus comprises standard IR diodes with non-coherent light. 
         [0026]    Even if the wavelength of the light is in the same range as for fiber optic rotary joints, the differentiator is the targeted distance between emitter and receiver: Where fiber optic joints are commonly designed for very small distances in the range of a few millimeters, the application here is intended for distances up to decimeters or even meters. A typical embodiment of the IR data joint as depicted in  FIG. 3  is designed for a distance between emitter and receiver in the range of centimeters. 
         [0027]    While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.