Wind power in West Texas

During our recent flight from Las Vegas to Dallas (on 2011.09.11!), Carla took some great shots of the Wildorado Wind Ranch near Wildorado, Texas (a bit west of Amarillo). (Not a "wind farm"? Farm in West Texas? God forbid!)

Here is one of my favorites:


The facility comprises 70 Siemens Mark II series wind turbines, model SWT-2.3-93.

They are 295 ft (90 m) tall at the hub, and the rotors sweep a circle 305 ft (93 m) in diameter.

Their rated output is 2.3 MW each (attainable for a wind speed of at least 33.5 mi/hr - 15 m/s), a total prospective capacity for the field of 161 MW. They are among the most powerful wind turbines in use today. The corresponding rotor speed is about 16 rev/min. The generator proper operates at 91 times the rotor speed via a compound planetary gearbox with offset output (about 1500 rev/min for rated output).

The rotor weighs approximately 66 tons (60 Mg). The nacelle (which contains the gearbox, generator, etc.) weighs approximately 90 tons (82 Mg).

We have not yet identified the wonderful canyon along which the machines are arrayed.

Here we see a Siemens photo of one of these machines:


We have earlier seen these machines in pieces traveling along the highways near our home. Very impressive!

This satellite image from Google Earth shows the overall field. Most visible is the network of roads connecting the pads on which the turbines are sited.


The outline on this insert shows the general area covered by Carla's photo:


All neat stuff!

Best regards,

Doug

I noted above that in the multi-stage planetary gearbox that increases the rotor speed to the generator speed (91x) in the Siemens SWT-2.3-93 wind turbines, the output shaft is offset. Inherently, the input and output shafts of a planetary gearshift are coaxial (inline), so one must go to some trouble to arrange otherwise.

It didn't seem that this was necessitated, for example, in terms of where the generator must be placed.

I now find that the motivation is to provide for a clear passage through the center of the planetary gearbox and ultimately thorough its hollow input shaft to the hub of the rotor to accommodate the power and control leads for the motor drives that control the blade pitch.

Although not really related to this issue, it is interesting to note that the rotor axis is pitched up by 6° (up in the direction into the wind, which is the direction away from the nacelle containing the gearbox and generator). Evidently one motivation of this is simply to provide more clearance between the rotor blades and the mast without having the rotor hub farther from the mast axis, which increases the potential torque in yaw (rotation of the system around the vertical axis) which must be overcome by the yaw drive system.

Best regards,

Doug

This figure, courtesy of Siemens Wind Power, shows the arrangements in the nacelle of the specific model (SWT-2.3-93) used at the Wildorado Wind Ranch:



In this photo, of a slightly different version of the same general model, we see the assembly comprising the generator, gearbox, rotor shaft bearing system, rotor shaft, and rotor hub flange being put into place in the nacelle. It gives some idea of the scale of the machine.



The four objects that look like sump pumps are yaw drive motors, which control the "aim" of the nacelle and rotor; there are four more further back (one mechanic is evidently sitting on one of them!). They operate on a ring gear located below the "floor" of the nacelle (item 15 on the figure above), affixed to the top of the mast.

Best regards,

Doug