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Forum Index : Windmills : Generator power outputs

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The_Professor

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Joined: 22/04/2007
Location: United Kingdom
Posts: 11

Posted: 09:54pm 21 Apr 2007

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I appreciate blade design, tower height will have an effect on generator power outputs, however is there any way to access what power output can be achieved if all the conditions are right?

Thanks in advance

Gizmo

Admin Group

Joined: 05/06/2004
Location: Australia
Posts: 5116

Posted: 11:25pm 21 Apr 2007

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Hi Professor. I like the little animated avatar.

Yes it is possible to work out the windmills expected power, give or take. The Warlock Blade Calculator will give you shaft power based on wind speed and turbine specifications. And we can measure the alternator efficiency with a test rig, a bit involved, but can be done.
But in practice there are a lot of variables that we wont be able to nail down. eg The blades efficiency wont be known exactly, or the real world wind conditions at the top of our tower. So its always a guess, you could never say your windmill will make this much power in this wind untill you actually build and test it.

Glenn

The best time to plant a tree was twenty years ago, the second best time is right now.
JAQ

The_Professor

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Joined: 22/04/2007
Location: United Kingdom
Posts: 11

Posted: 12:57pm 22 Apr 2007

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Hi Glen,

Thanks for the reply

I have already put the genny in a lathe to see what voltage outputs I get (see another thread want other peoples genny output voltages). So I'm now wondering if I should keep on increasing the load (resistance - ohms) to see how hot the genny gets. Or is there some other way?

I totally agree about the try it and see comment as every site, blade etc. can be dramatically different, so sticking it in the wind is the only real test.

KiwiJohn
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Joined: 01/12/2005
Location: New Zealand
Posts: 691

Posted: 06:48pm 22 Apr 2007

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Hi Professor

Maximum power transfer will occur when the impedance of the load is equal to the impedance of the source so there will be some load level which will provide maximum power.

There is a paper online at http://mtbest.net/SD_modification.pdf which you may find informative. The alternator he examines is the Fisher and Paykel washing machine motor much beloved by many members of this board!

The_Professor

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Joined: 22/04/2007
Location: United Kingdom
Posts: 11

Posted: 05:44pm 01 May 2007

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Hi,

Thanks for the link

There is quite a bit of interesting information there. It clears up a query that I had, as to why I get strange wave forms when viewing the generator output on an osciliscope.

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