Asynchronous generation

[Brian Bruns]

Hi All,

I was wondering if anyone has experience with asynchronous generators? I bought the plans for one on-line, and was curious to the efficiency. It appears to be a very economical way of DIY grid tie generation. Have a look at their site; www.prairieturbines.com. Let me know if you have experience with this type generator.

Brian

[Mark Parsons]

Greetings Brian,

I have experimented with a 3 phase induction motor. Added capacitors to the phases in a C-2C configuration to get single phase AC out. Works great as long as motor (generator) is not loaded until up to near rated speed. Efficiency is as motor is rated.

A couple of references I found useful:
http://www.qsl.net/ns8o/Induction_Generator.html
http://www.redrok.com/cimtext.pdf

My plan is to integrate a high efficiency induction (motor) generator into a microhydro solution. RPM's are fixed vs wind is variable.

The gearbox on the Prairie Turbines looks like a stock Nord Helical Gearmotor unit. How are they controlling the RPM's to maintain grid frequency? Maybe letting it motor under light winds and then generate with heavier winds? If so, pretty simple. Would need to make sure that winds are well above production cut-in speed constantly or else your paying to have a big fan blowing on the top of the tower. Maybe OK if growing citrus.;)

Are you planning on building one?

Regards,
Mark

[Brian Bruns]

Hello Mark,

I am planning on building one of these. It is supposed to energize and start producing in a 6-8 mph wind speed. They sell a controller that is motor RPM triggered. It does not engergize the fields until the RPM reaches above rated speed, then signals a relay to energize. The controller also de-energizes in case over/under voltage occures, or overspeed. The Nord gear motor has an effective brake that comes on when not electrically released to stop turbine in extreme wind.
They claim the blade design helps create early cut-in speeds, and also basically starts to stall in too high of wind speeds. ( 2.1 kwh @ 8 mph - 5.5 kwh max ) If home built, the payback time is 2-3 years. Just found out from my local utility company I can hook this up after they look at the schematic and components used. Hopefully cut those bills down a tad !!!:p


Thanks for the reinforcement, Brian