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gerd30kwselfbuild
PostPosted: Thu Jun 26, 2008 10:49 pm    Post subject: Rotorspeed/ Windspeed Reply with quote



Joined: 17 May 2008
Posts: 11

Hi Erik,

I need to know the different Rotorspeeds according to the Windspeed of the 4,8 m Blades. I think the optimal V-Tip/Vwind of 5,5 should be reached around 4-6 m/s. I that right?
The maximum Power of this Blades is around 12m/s and at 75 rpm, than we have a V-Tip/Vwind of around 3,4. Thats also ok at such Windspeed..
But at the beginning how much rpm does the Rotor make at 3 or 4 m/s?


Do you have some data of the practical Rotor rpm in addiction to the different Windspeeds?
Or on the other way around, some information whitch V-tip/Vwind is good to use in addiction to the different Windspeeds?

thank you,

gerd
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erik
PostPosted: Fri Jun 27, 2008 3:47 pm    Post subject: Reply with quote

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Joined: 28 May 2007
Posts: 35

Hi Gerd

Before I find the old graphs, a couple of questions : are you running:
Fixed pitch ? , fixed or variable rpm ? Most early turbines here, had f.eks. a 55 kW main generator, and a low speed an 11 kW generator (typically V-belt drive between the main and small generator - both running 1500 rpm - enabling the turbine to turn slower at low winds), to better pick up the energy at lower windspeeds. ( 22 kW and and 5 kW)..

br

Erik
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gerd30kwselfbuild
PostPosted: Fri Jun 27, 2008 5:51 pm    Post subject: Reply with quote



Joined: 17 May 2008
Posts: 11

Hi Erik,

My Turbine has a fixed pitch, and a diameter of 10,6 meter.
The mashine will work with variable rpm( i use a synchron mashine with 27kva).
Last week I finished the gear, I will have 1500rpm at the alternator with a rotorspeed of 73 rpm.
I need to know what is a practical rotorspeed for example at 3m/s so that i could dimension the exciting voltage to the rpm of the mashine.

In the data sheet "aerostar3" there is a fine characteristic curve of the rotorblades displayed, but i miss the belonging rotorspeed. There is only an entry of 76 rpm at " full power".

best regards

gerd
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erik
PostPosted: Sun Jun 29, 2008 4:24 pm    Post subject: Reply with quote

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Joined: 28 May 2007
Posts: 35

Hi Gerd,

The graph in "aerostar3" is for a fixed pitch and fixed rotor speed machine. If the turbine itself or by means of a "motor start up" is brought to 76 rpm it will produce 0 kW at 3 m/s. But .. as the lambda (tip speed ratio) is then 14..far away from the max. perform..... it will work very bad. ( that was the reason, why many fixed pitch, fixed rpm machines had an additional small generator, running at a lower speed).

As you are lucky to have variable speed you can use the optimum lambda all the way up to maximum power.

At 4 m/s you could choose 4 * 5.5 m/s = 22 m/s for tip speed - which with your 33.3 m perimeter rotor gives (0.66 Hz or) 39.6 rpm

best regards

Erik
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gerd30kwselfbuild
PostPosted: Mon Jun 30, 2008 12:12 am    Post subject: Reply with quote



Joined: 17 May 2008
Posts: 11

hey erik,
of cause a variable rotorspeed has much advantages, but i did not understand yet, how i must control the exciting voltage. I planed to make the exiter voltage addicted to the speed of the alternator, but wenn i work with an constant lambda of 5,5 then i have my 1500rpm on the alternator at a windspeed of 7,5 m/s.
but at 7,5 m/s i have got the problem that the wind has not enough power for my 27kva alternator.

so i think i have two options to solve the problem: at first i could change the lambda at higher windspeeds, so that the 1500 rpm are reached at around 12m/s.
the second possibility is to have from 7,5m/s to switch off windspeed, a fixed engine speed. Than i must control the exciter voltage according to the windspeed to make shure that i don“t demand to much power from the wind. But how to detect/control this?
What do you thing is the better way to solve this problem?

nice greetings
gerd
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erik
PostPosted: Mon Jun 30, 2008 8:55 pm    Post subject: Reply with quote

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Joined: 28 May 2007
Posts: 35

Hi Gerd,

Your last message gets me into unknown land ... of exciting synchroneous alternators etc. You could try a contact to a guy who has tried this, I think:
Claus Nybroe of www.windmission.dk - send him a mail and send greeting from mee... (Maybe Claus worked with a synchroneous alternator together with Peter Rasmussen) (Peter Rasmussen was with RISŲ in earlier times, then the Nordic Folkecenter, then Belt Electric (PMG) and now Gamesa in Denmark.)

Good luck

Erik
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marson
PostPosted: Wed Dec 07, 2016 9:08 am    Post subject: Reply with quote



Joined: 08 Oct 2016
Posts: 26

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kirril
PostPosted: Sun Jun 25, 2017 10:03 pm    Post subject: Reply with quote



Joined: 22 May 2017
Posts: 3

Thanks guys for all of the responses
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