Homebrewed Electricity > Wind

Help needed on a Breezy type grid tied induction turbine

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Kyle:
Hello to everyone. I am new to the forum. I have been reading and learning what I can over the last month. I am new to wind turbines.

My project is a small turbine(750 watt) with a 3 phase/220 volt motor and a 10:1 gearbox. I have been reading about the Prairie Turbines “Breezy 5.5” and am trying to do something like that only smaller. Their web site is shut down and my attempts to contact have failed thus far. I was hoping to find one of their books which may explain some of my questions.

My current hurdle is the wireing of the 3 phase to the single phase grid. I read that the Breezy did this without a converter. Could someone with knowledge of this explain how to wire my motor to accept the single phase 220 v?

paara:
You are trying to connect you 3 phase wind turbine directly into a 220v grid, without an invertere?

JW:
Post some pictures so we can get a better idea of what your trying to do. Also it may not be possible for what your trying to do.
: with what you have.

Kyle:
Thank you for the reply. Here is a picture of the project.  I don't have a picture of the wiring block but it is a standard 3 phase/220 volt setup with 3 leads. I can't tell if it is delta or star setup as yet. Hopefully I can figure it out when I open it up. I think I have the wiring bypass figured out. It sounds like adding some capacitors to one of the 3 phases will trick it to think the single phase is 3 phase. My 3 wires will be, 1 - 220v +, 2 - neutral, and 3 - 220v+ through capacitors. I understand I will be sacrificing 60% power to do this.  I will be pulling it down and experimenting this weekend -weather permitting.

george65:

I believe the wiring setup you are looking for is called C2C.
It's a pretty common way to convert 3 phase to single.

One leg from the motor goes straight through. The 2nd leg has one  cap and the third leg has 2 caps of the same value or 1 cap of Double the value. you can wire them 1-2, 2-3 and leave 3-1 open or direct connected. Use 440V caps or the highest you can get.
You can tap off any 2 legs you want back to AC.
The trick will be working out what the value of the caps is. For a 750W motor I'd guess something around 10-15Uf.

Hard to say because what I have dealt with is constant speed and the problem with this setup would be the motor has to be over synchronous ( nameplate) speed in order to generate. In low winds the thing will - motor. You will be using power not making it.

I can't see how you would prevent the thing becoming a fan not a generator in low wind without some sort of controller or relay etc.
Not that my lack of knowledge means much but If I am right, could be the reason this site closed down... because their idea/ product didn't work!

You can't use a Diode or you'll loose AC and the thing needs to be phase locked in order for this to work.  You could maybe use a relay powered by the generator. once it came up to speed ( voltage) it would engage the AC.  Problem here is when the wind stopped, the relay would probably drain the windings making it necessary to flash them to get some residual magnetism before the thing would generate again.
An SSR may overcome this. 

You'd need an arduino or something to sense the speed and which way the current was going.
Only other thing I can think of is using a PWM controller. Not sure if it would work but they are $3 on fleabay so if it didn't work and you blew the snot out of it, hardly any big deal.

I was thinking what would work would be a solar grid tie inverter. You'd only need a  little one so the cheapest you could buy used would be the go. Again, rectify the output to DC then feed it into the inverter. The problem I see here would be on a turbine there would be some oscillation as the inverter tried to find the sweet spot and loaded the motor up and down. If the motor dropped below sycronous speed it would loose field current and  drop out. On 3rd thoughts, the inverter would have a voltage cutoff so once the power got below 90-150V, whatever the threshold for that particular inverter was, it should drop out and not de saturate the residual flux in the motor windings allowing it to come up to speed and energise again.

Without some sort of current limitation though ( another controller) I think the things would be ramping up and down all day.

The other thing to be aware of is this will NOT be a 750W generator. In practicality you'll  get around 300W off the thing if you can drive it hard enough. After that the voltage in the windings in the motor will get too high and you'll get overheating.

Normally this sort of setup is used for Driving a motor off an engine. You get the engine driving the motor near synchronous speed, Connect the AC then bring the engine up to speed at which point the motor starts generating. The power generated is controlled by the engine speed and the value of the caps.  Higher caps make more power at lower speed and vice versa within limits.

Be interested to see if anyone else here knows how to prevent the thing becoming a fan without the use of a controller.

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