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I've been designing a Darrieus wind turbine for a while now. The spec is as follows:
approx 200 rpm
Asynchron motor/alternator connected to the grid
No gearbox
Roughly 2 kW peak power
Unfortunately, the low rpm amounts to a large number of poles needed on the motor/alternator. Most standard motors have 2 or 4 poles giving me 1450 rpm as the lowest speed. Quite a gearbox needed.
I read about the washing mashine motor on this page. Could that be an alternative? What power does that have?
Many thanks
/Jonas
GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127
Posted: 11:56pm 29 Feb 2008
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Hi Jonas,
for 200 RPM would require 30 poles for 50Hz AC.
Grid connection has many rules. Anti islanding etc.
You would probably need 10 or so std. F&P alternators for 2kW. The matching of turns etc to required output voltage needs to be calculated.
I know of many failures with direct connected wind/grid systems.
I have found grid connect solar inverters offer a solution. Operating voltage limits have to be maintained.
I buffer the wind energy with a battery and voltage regulating DC/DC converter and then grid feed the surplus at a relatively constant voltage. The solar grid inverter handles the constant voltage, changing current better than the changing voltage and current, that is normally produced by a windmill.
My 2m HAWT produces up to 2.5kWhr RE per day that supplements power provided by the utility grid. About half of this power was previously wasted in a dump load. I have been able to get additional use from my solar grid system, so I didn't need a new special inverter.
If you get a direct connected system to work, then I imagine many people will be knocking on your door.