Load and Inverters

[newind]

Ok, so for the record newind does not mean New England Wind. It means New-Wind as in I'm very new to wind. So now for the newbie question.

I have made a small turbine and have it coupled to a generator. The generator is making 170Vdc after rectifying at around 2-1/2 amps.

I've tested it by loading it with a 100w 8ohm resistor. Then with 200watts @ 4ohms and the shaft speed drops significantly. I have not bought an inverter yet, and was wondering if, I did connect it to an inverter will the inverter isolate the generator from the load? Or, once the inverter connects to the grid will it (the turbine) see that load, and do as it has done with the resistors, and drop my shaft speed significantly? Meaning i will not make power....

Any input on this would be great. Its the missing link for me right now.

Thanks,

newind... remember new to wind... be gentle!

   

[ghurd]

Define "inverter".

"wondering if, I did connect it to an inverter will the inverter isolate the generator from the load?"  Not most inverters sold on the market.

"once the inverter connects to the grid"?

Rethink the entire system.  Or do a price check on legal grid tie inverters, and then read the PDF manual for the inverter of your choice.

"the shaft speed drops significantly", as it is supposed to.

It is either running away before, or stalling now.

G-

[AbyssUnderground]

Never connect the inverter directly to the wind generator. There is too much voltage fluctuation and you will fry it. Simple as that. The inverter will be designed for a very small voltage range, e.g. 12v will run on 10.5v-15v at most. Anything more will fry it, anything less and it won't work at all.

You MUST use a battery as a buffer. That way the inverter always sees a steady voltage and the turbine has a fairly fixed resistance to put power into like you would see with a resistor. (I think I got that last bit right!).

Never the less, you must use a battery, that should be common knowledge. And it must be sized appropriately to the turbines output or you will easily cook it if its too small.

Remember you'll need a proper wind charge controller too, with diversion loads to stop the battery frying when its full. Don't use a solar controller, they open circuit when they reach full and the turbine will run away and fly apart.

[newind]

Running away - meaning open circuit voltage, right? and stalling - seeing a load.

I am looking at a windy boy to do the grid tie with, but if i see the kind of stalling that i have when i put my resistors in place... well then most likely it wont work. It drove my rotational speed down by half!

Is that what I can expect to see when the inverter connects to the grid?

thanks, new

[ghurd]

Stalling, simplified, is when the blades are not making enough power to keep turning faster as the wind speed increases.

Google search the board, top right menu box, for more info about stall and stalling than you ever wanted to know.

The 170VDC is open circuit, and the 2.5A is short circuit?

It looks like the generator / alternator has some issues with very high resistance.

I would recommend more in depth testing of the alternator before spending big bucks on an inverter.  I would be surprised if the alternator can make 200W output.

If spending money and effort on grid tie, certainly want to have a better alternator.

G-