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Power-Distributor Controller for Wind Turbine

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umagrama

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Hello guys,

I am trying to figure out how to build a power-distributor controller for my wind turbine that would do the following task:

- IF (power generated >= power demanded) THEN bypass battery bank and supply the household straight from the wind turbine.
- IF power generated < power demanded THEN supply household hold through battery bank ( while still charging the battery with power generated).

Specs of the system:
- Power generation by wind turbine 500-2000 W
- Battery bank 24 V
- load is variable

I was thinking op-amps (comparators) and switches (transistors) but I've never dealt with high power circuits before. I really would appreciate any assistance available out there. How could I make this possible?

Thank you all for reading and helping out! :)

(edited for typos)
(edited for more info)
 
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Does your wind turbine generate power at the frequency that the household expects?

Oh, and you have expressed a common misconception:
- IF power generated < power demanded THEN supply household hold through battery bank ( while still charging the battery with power generated).
Should be rephrased:
- IF power generated < power demanded THEN supply household hold through battery bank ( while the battery discharges, supporting the excess demand.)

Your design must recharge the batteries. The best time to do this is when (power generated >= power demanded).
 
mneary,

Answering your question, the turbine generates AC rectified into DC and back to AC using an inverter.

I see what you are saying. You're right. I should rephrase it. What I am trying to do is use the batteries ONLY when needed; if batteries are recharged to 100% and there's enough wind to supply my home then I don't want to use the lifetime of the battery since I already got enough instant power to supply whatever I got running.

So yeah, another if statement:

IF (power generated > power demanded) AND (batteries = full) THEN bypass battery bank and wind turbine supply home
IF (power generated > power demanded) AND (batteries =! full) THEN recharge battery bank and batteries supply home
IF (power generated < power demanded) THEN attempt to charge battery (the voltage could be too low to recharge batteries) and batteries supply home

Does it make more sense now? Is this doable? How could I "compute" the power demanded in real-time?

Mahalo!
 
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You're making this far more complicated than it is - you should run off the batteries ALL the time, with the turbine charging the battery - it will automatically feed the load from the turbine rather than the battery, just as your car alternator does.

The control you need is just to stop the battery been overcharged, so once the battery is fully charged you need to dump the output from the turbine into a dummy load to get rid of it.
 
Wouldn't running the battery all the time 'minimize' the battery life? My goal here is to max the lifetime of the battery bank -- batteries aren't cheap. I've read that using only 20% of the battery charge is ideal for maxing the lifetime of the battery. Batteries don't die, people kill batteries.

That's what I was thinking of doing... saving on the batteries.

(The overcharge deal and a dump load is work of the charge controller.)

Thanks for the response!
 
Wouldn't running the battery all the time 'minimize' the battery life?

No, just like in your car, the alternator feeds the load, with the battery only providing power when the alternator can't provide enough.

You do need to provide a system to disconnect the load once the battery gets below a certain charge level, to avoid over discharging the batteries - but this had nothing to do with the charging system or the alternator, or indeed with your original idea.
 
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Get a battery monitor. Or make one with a microcontroller. Based on your battery voltage and/or current usage, you could tailor your lifestyle to fit your battery health. Going only 20% depth of discharge is going to mean a pretty large battery bank?
 
Wouldn't running the battery all the time 'minimize' the battery life? My goal here is to max the lifetime of the battery bank -- batteries aren't cheap. I've read that using only 20% of the battery charge is ideal for maxing the lifetime of the battery. Batteries don't die, people kill batteries.

That's what I was thinking of doing... saving on the batteries.

(The overcharge deal and a dump load is work of the charge controller.)

Thanks for the response!

It's not really "running" the batteries all the time that reduces their ability to hold a charge. What really hurts batteries is the depth of discharge. Thus, if you're charging the batteries as fast as you're draining them, there's never much of a drop in voltage and it doesn't wear the batteries so much.

I haven't done the calculations out, but I'm willing to bet that a constant draw on the batteries while simultaneously charging them for an entire week would have less negative effect than bringing them down to 50% charge just once.
 
I would assume that the generator has a regulator, similar to a car generator, that controls the generator output voltage, which keeps the battery from overcharging. Thus the generator will provide whatever load it sees up to its maximum generating capacity (based upon the wind speed). If the battery is full and the generator is capable of providing all the household load then the regulator will adjust the generator output to supply the load, but the battery will essentially be just floating with perhaps only a small float charge current. This will have little effect on battery life.

All this means is that the setup you have is likely doing what you want automatically. The generator supplies the power required as available from the wind and the battery life is maximized.
 
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BTW, depending on the size of the blades, you may want a braking system.
 
If you use hot water use the dummy load to heat it up

in that case it still not wasted

An other point to exstend your battery banks life is make the room temp controled so your batterys face more or less the same phisical exsternal conditions at all times

if that is to much asked to build make sure your charge voltage is temparature corected

Robert-Jan
 
How do you prevent the batteries from totally discharging?

You need a low voltage disconnect to switch over to mains power.

The problem is is the switch is too slow apliances like your compter and digital clocks will be reset. One way of getting round this is to use a mains powered charger to recharge the batteries but this is inefficient. Another is to power the devices that you want to remain on all the time from the mains all the time.
 
That's a nice inverter! It's good for about 420 Watts tho. The nice thing is that it takes solar and wind power but then I think about how much power one could extract from the sun and the wind and you'd need a few of those at least to run the house (or part of the house).

I wonder how much it is. Definitely worth bookmarking it.

Thanks man!
 
Hybrid Inverter

Hi umagrama,

Well I sell them for $245 inc GST.

Wind Turbines Australia is my site. I waslooking for a solution for another problem on this site and came across your post.

Perc
 
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