Abstract:
A wind turbine, includes a tower for supporting a nacelle; a gearbox connected to an electrical generator arranged in the nacelle; a plurality of blades for rotating the gearbox and driving the generator; a brake disk for stopping rotation of at least one of the gearbox and the generator; and an auxiliary power source, driven by the brake disk, for generating power.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The subject matter described here generally relates to wind turbines, and, more particularly, to power generation using a wind turbine brake. 
         [0003]    2. Related Art 
         [0004]    A wind turbine is a machine for converting the kinetic energy in wind into mechanical energy. If the mechanical energy is used directly by the machinery, such as to pump water or to grind wheat, then the wind turbine may be referred to as a windmill. Similarly, if the mechanical energy is converted to electricity, then the machine may also be referred to as a wind generator or wind power plant. 
         [0005]    Wind turbines are typically categorized according to the vertical or horizontal axis about which the blades rotate. One so-called horizontal-axis wind generator is schematically illustrated in  FIG. 1  and available from General Electric Company. This particular configuration for a wind turbine  2  includes a tower  4  supporting a nacelle  6  enclosing a drive train  8 . The blades  10  are arranged on a hub  12  to form a “rotor” at one end of the drive train  8  outside of the nacelle  6 . The rotating blades  10  drive a gearbox  14  connected to an electrical generator  16  at the other end of the drive train  8  inside the nacelle  6 . A control system  18  receives input from an anemometer  20  and/or other sensors to control the operation of the wind turbine  2 . 
         [0006]      FIG. 2  is an enlarged cut-away view of a top portion of the wind turbine  2  shown in  FIG. 1  and is partially reproduced from commonly-assigned U.S. Pat. No. 7,488,155 entitled “Methods and Apparatus for Wind Turbine Braking.” In  FIG. 2 , the control system  18  includes one or more controllers within a control panel for monitoring the anemometer  20  and/or various other sensors  22  for managing various aspects of the turbine operation. For example, the control system  18  may provide signals to the variable blade pitch actuators  24  that adjust the pitch of blades  10 . Similarly, the control system  18  may also provide control signals to the yaw drive actuators  26  that engage the yaw deck  28  and rotate the nacelle  6  about the yaw axis  30  which is substantially perpendicular to the rotor axis  32 . 
         [0007]    The wind turbine  2  typically has numerous devices that are powered by batteries in order to operate during a power outage. Recharging those batteries is generally not possible if the turbine  2  is spinning freely but not generating power, such as when idling or coming up to speed during a cold start. Wind turbines  2  also generally include redundant braking systems for locking the drive train  8  and/or blades  10 . At least one of those braking systems typically includes a brake disk capable of stopping the turbine  2  against full wind torque. These wind turbine braking systems often further include a hydraulic accumulator, spring, or other energy storage device that enables operation of the brake in the event of a power failure. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0008]    These and other aspects associated with such conventional approaches are addressed here in by providing, in various embodiments, a wind turbine including a tower for supporting a nacelle; a gearbox connected to an electrical generator arranged in the nacelle; a plurality of blades for rotating the gearbox and driving the generator; a brake disk for stopping rotation of at least one of the gearbox and the generator; and an auxiliary power source, driven by the brake disk, for generating power. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Various aspects of this technology will now be described with reference to the following figures (“FIGS.”) which are not necessarily drawn to scale, but use the same reference numerals to designate corresponding parts throughout each of the several views. 
           [0010]      FIG. 1  is a schematic side view of a conventional wind generator. 
           [0011]      FIG. 2  is a partial cutaway view of the upper portion of the wind turbine shown in  FIG. 1 . 
           [0012]      FIG. 3  is a schematic view of a gearbox system for use with the wind turbine shown in  FIGS. 1 and 2 . 
           [0013]      FIG. 4  is a schematic view of a gearbox system for use with the wind turbine shown in  FIGS. 1 and 2 . 
           [0014]      FIG. 5  is a schematic view of a gearbox system for use with the wind turbine shown in  FIGS. 1 and 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0015]      FIGS. 3 through 5  are schematic views of a gearbox system  100  including a gearbox  14  and various auxiliary power sources and power storage devices. The gearbox system  100  may be used with the wind turbine  2  shown in  FIGS. 1 and 2  and/or any other on-shore or off-shore wind turbine or other device utilizing a suitable gearbox  14 . For example, the gearbox  14  of the gearbox system  100  may be connected to the generator  16  arranged on the tower  4  as shown in  FIGS. 1 and 2 . 
         [0016]    The gearbox  14  has a brake disk  102  that is activated by a brake (not shown) for stopping rotation of the gearbox  14 . The brake disk  102  illustrated here is arranged on the high-speed side of the gearbox  14 , between the gearbox  14  and the (main) generator  16 . The brake disk  102  is typically attached to the shaft of the gearbox  14 , but may alternatively be attached on the generator side of the gearbox  14 . Other brake disk arrangements are also possible. 
         [0017]    One or more auxiliary power sources may be mounted on or near the main gearbox  14  and driven by the brake disk  102  in order to generate power. For example, the auxiliary power source may include an alternator or second (auxiliary) generator  104  as shown in  FIGS. 3 and 4 , or a compressor  106  as shown in  FIG. 5 . The second generator  104 , compressor  106 , and/or other auxiliary power sources may also be provided on the same gearbox system  100 . 
         [0018]    In  FIGS. 3 and 5 , the second generator  104  or compressor  106  (respectively) directly engage the brake disk  102 . In these examples, both of the second generator  104  and compressor  106  have a pinion on its shaft that engages gear teeth on the brake disk  102 . However, the second generator  104  and/or compressor  106  may also be driven by other devices that engage the brake disk  102  such as a gears, wheels, chains, belts, couplings, clutches, and/or other devices. The engagement can be made by a permanent fixture, or alternatively, one that is engaged only as needed. 
         [0019]    As illustrated in the embodiment shown in  FIG. 4 , the second generator  104  may include an armature  108  that surrounds a portion of the brake disk  102  having a magnetic field inducer such as permanent magnets  110  or field coils (not shown). In this case, the brake disk  102  does not require teeth. The positions of the armature  108  and permanent magnets  110  may also be reversed. Power from one auxiliary power source may also be use to drive another auxiliary power source. For example, compressed air from the compressor  106  may be used to run an air-motor that can drive a third generator and/or other devices. 
         [0020]    A power storage device may be connected to any or all of the auxiliary power sources for receiving and storing power from those power sources. For example, as illustrated in  FIGS. 3 and 4 , one or more batteries  112 , capacitors  113  (such as ultracapacitors), and/or other energy storage devices may be connected to the second generator  104  for receiving and storing electricity from the second generator  104 . Similarly, as illustrated in  FIG. 5 , one or more gas cylinders  114  or other reservoirs may be connected to the compressor  106  for receiving and storing air or other pressurized fluids from the compressor  106 . Energy from these power storage devices can then be used for a variety of tasks. For example, energy from the battery  112  may be used to power pitch control actuators  24  or  116 , heaters, such as gearbox oil heater  118 , and/or other auxiliary devices. Similarly, energy from the gas cylinder  114  may be used to power air motors  120 , battery chargers  122 , hand power tools  124  and/or other devices. Energy may also be provide directly to such loads from the second generator  104  and/or compressor  106 . 
         [0021]    The technology disclosed above offers various advantages over conventional approaches. For example, the auxiliary power sources draw minimal torque from the brake disk  102  wheel, the majority of which is then fed into the generator  16  that produces power for the grid. These auxiliary power sources can provide power even when the generator  16  is off-line. Where the output of the second generator  104  is used to recharge batteries, this stored energy can later be used to provide power for various purposes including pitch control actuators  24  or  116  and gearbox oil heating  118 . Such heating is particularly important in getting the wind turbine  2  for power production during extreme cold weather and could therefore help to quickly bring the wind turbine  2  to power production and thus increased the overall power production of the turbine  2 . Where the output of the compressor  106  is used to compress air, this stored energy can later be used to power hand tools that are used for maintain the wind turbine  2 . Since compressed air-powered hand tools  124  are relatively light weight, this aspect of the disclosure avoids the need to manually carry heavy tools up the tower  4  into a nacelle  6 . 
         [0022]    It should be emphasized that the embodiments described above, and particularly any “preferred” embodiments, are merely examples of various implementations that have been set forth here to provide a clear understanding of various aspects of this technology. One of ordinary skill will be able to alter many of these embodiments without substantially departing from scope of protection defined solely by the proper construction of the following claims.