Newbie power question

[arbela47000]

On a wind turbine generator, when the wind speed is variable, what aspect of the power output from the generator changes, the voltage or the current?

Can the charge controller deal with changes in either?

If I run a 48V system and mount a 120V, 640W generator, will that give me 13.3A of current?  How will this change as wind speed changes?  Is that generator overpowering the system?  Will that be detrimental, or will I just be wasting the generator's potential?

Electricity has always seemed a bit of a magical force to me, but I'm trying to rectify that shortcoming.  Any help you can provide would be greatly appreciated.  Thank you.

[Flux]

"On a wind turbine generator, when the wind speed is variable, what aspect of the power output from the generator changes, the voltage or the current?"

Ideally both will change but in your example only the current will change.

The charge controllers function is effectively to maintain the voltage constant. The battery does this until it is nearly fully charged and no controller is necessary. It is only with a full battery that the volts start to rise out of control to the detriment of the battery and the controller prevents this.

Your last bit of the question is too difficult to answer honestly but effectively your 120v generator will not be able to produce much more than nominal 48v. Its current will be limited to the 120v value for its own safety. I don't know where 13A comes from 640W at 120v is about 5.3A and it won't do much more for long is 640 is maximum rating.

What will happen in reality is very complex and we have no information to answer it. If it tries to produce much over 5.3A for long it will fry. Probably it will load the propeller down to a point where power is restricted and it may not even get to 5.3A

For normal operation the generator should make battery volts at cut in ( low wind) the actual generator voltage doesn't mean much as the battery will dictate what volts you get. At some point in higher winds the generator open circuit voltage will be in excess of your 120v and may be nearer 200 but you don't want this at cut in.

If your nominal 120v was at about twice cut in speed of your prop then it would be in the right order but in wind terminology we should consider it nearer a 50v generator.

These things are special, you don't use standard commercial generators intended for fixed speed working with an engine.

[Todd a]

Chancer are the inverter will only accept a specific voltage range.  If you have an inverter that can handle 30-45v and connect a 36v system to it you would likely only be able to generate power during specific wind speeds.  Now this sounds like most of the time you will not be generating electricity.  Well that is part of the reason for a taller tower.  The higher you go the stronger the wind is and the less turbulence you get into.  Now the furrowing system is supposed to keep the RPMs from getting too high will also keep the voltage from getting too high.  Another thing is at lower power if the inverter cuts out at a low voltage, the load will drop off and the turbine will start spinning up faster.

A better quality inverter can handle a bigger input voltage range.  Either way the output will still be the same voltage, but the amps will vary according to what the turbine is putting out.  Batteries and charger regulator can help to stabilize the output before the inverter.

[arbela47000]

640W/48V=13.3A

That's where 13.3A came from, but you have made it obvious that that won't happen from this system.  Also, this 120V generator is being sold as a variable-speed model that would be acceptable for application as a wind generator.  Now I just have to convince my wife that this is a good idea. :-)