Mini wind farm

[smcardle]

Hi All,

This is a question that may sound completely stupid to you guys in the know but what happens when you connect multiple wind turbines in parallel and series?

Lets assume that I have 5 mills and they are each manufactured and rated exactly the same. They are mounted in 5 different locations where the wind speed is different at each location thus each is generating a different output power curve (voltage/ampage) at the same time.

So what would be the net effect of connecting the outputs of each turbine in parallel and in series?

This may seem like a funny question but I want to place several small VAWTS on my land and accumulate the power generated between them as opposed to building one large VAWT that would possibly draw complaints from the neighbors (a HAWT is out of the question). As these will be mounted close to ground level they will be mostly driven by turbulent winds/gusts which are not the same at any two points on my property so I expect each turbine to generate different outputs at any one point in time.

Steve

[ghurd]

Parallel is fine.

Series increases the resistance, reducing the output.  It is worse if one is turning well while the other is turning slow.

"Small" means high resistance. No reason to double it while one half isn't working as well as the other half

G-

[wooferhound]

None of us have been able to make a VAWT that produces usable power. What kind of VAWT are you making that you think will work?

[electrondady1]

woof ,

i take exception to your blanket statement that no one on this board has been able to make "usable power" with a vertical axis windmill.

i give for example a man named Ed Lenze.

smcardle,

the question you have asked is one i asked almost 5 years ago when i discovered this forum and began to study.

the output from each alternator needs to be rectified to d.c. separately.

[wooferhound]

Well ,  Yes you are correct

only one of us has been able to do it

[thefinis]

Not quite right either as there have been at least two other folks with working/producing vawts but both of them were based on Ed's design. Gizmo had one up and making power not sure if it is still up and the one that (?Wayne) built that was portable (if you had a pickup truck). His was taken out in a storm by a tree limb. He did rebuild it but I think he made it a 2 wing instead of a 3 wing. Hmmmmm do not remember hearing anything about it after the conversion.

Vawts can fill some niches and if you want something to watch spin and make a little power why not a vawt? The thing is most vawts tend to be yard art that can make some power and tend to be more art than anything else. One big drawback is how material intensive a vawt is when compared to a hawt of the same output. The extra weight means they are usually placed on a low tower or at ground level. This just compounds the power output problem due to lower wind speeds. Will a vawt work at ground level? Yes! Will it work well? No! Is it worth doing even if it ends up with just watching them spin? All the neighbors and the wife think so. Sometimes I'm not sure.

Finis

[electrondady1]

i can't remember the final result as far as power output goes but

cmebrew did some nice work with this unit.

http://www.fieldlines.com/story/2007/10/5/1192/20143

[smcardle]

Thank all,

I was thinking there for a while that wooferhound didn't like VAWT's but I just read a post where he seems to be in the mood to create a new VAWT design of his own.

The reason I want to use VAWTs is because I need my mills close to the ground and to operate in turbulent wind conditions. I realise I will not get as much power from the wind as I would get using a HAWT.

The mills I would like to build are very light weight with blades only 18 inches high by 12 inches diameter and I have kind of settled on a helical blade design. I will mold the blades as a single unit from recycled plastic and force fit these onto the top of my 11.5inch diameter generator. No amount of wind stress would cause bearing failure at these sizes.

Any initial guesses about the maximum wattage I could expect to get from a 11.5 inch diameter PMG at say 150 RMP? I think I would like to get up to or beyond the 48Volt mark most people aim for here. This would allow thinner wire to be used to connect the mills over a greater distance with less line losses.

Anyway, back to original question I had.

Should I rectify the output of each mill separately ? or should I parallel all the outputs and rectify the result ?

What would be the advantage/disadvantage in each of these scenarios?

Thanks again folks, this site is just great

Steve

[ghurd]

Rectify each separately.  No question about it.

If they are paralleled and then rectified, currents and voltages will be all over the place.

Nothing will be in phase. One will short out another. Current will be going backwards.

G-

[luckeydog]

well here is a 10 kw  VAWT