Author Topic: Stall regulated wind turbine  (Read 1666 times)

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stofanel

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Stall regulated wind turbine
« on: September 04, 2015, 02:29:19 PM »
The most common methods to control turbine over-revving are furling and variable pitch control. The new trend, however, is to implement stall control. As the wind speed increases, the local AOA increases and puts the airfoil into a stall and therefore increases drag. An extensive internet search however, has yielded very few useful results on the design and implementation of such methods. Is anyone familiar with and/or have some useful links on this topic?

boB

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Re: Stall regulated wind turbine
« Reply #1 on: September 04, 2015, 06:12:05 PM »

What does "AOA"  stand for ?  Probably staring me right in the face, but AOA  might not give the proper hits from Google ?

Don't forget about dump loads (clippers) too

boB

dnix71

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Re: Stall regulated wind turbine
« Reply #2 on: September 04, 2015, 09:30:37 PM »
AOA = angle of attack.

High tech now is to feed back into the coils to slow the mill. It's always nice to have several braking methods built-in. If one fails there are backups. Furling plus dump load plus magnetic brake plus centrifugal clutch brake makes for a safer mill.

Flux

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Re: Stall regulated wind turbine
« Reply #3 on: September 07, 2015, 03:55:46 AM »
Stall works fine when set up properly, but what dnix71 mentioned is very important here. If you loose the load for any reason you will come out of stall and the prop will run away.

Tip brakes that flip open and produce drag are usually used with stall but other mechanical schemes can be used. With pitch control, relying on electrical braking is risky as a cable fault will kill the braking mechanism.

Stall is most effective on constant speed machines such as induction generators, it should work on a heavily overloaded axial machine but beware of the case where at some wind loading the generator fails to produce enough load or it will pull out of stall and you will need the back up braking to save things.

There are blade profiles designed for stall operation and you will get better results with them but it works to some extent with any prop.

Flux