Small wind farm: connecting turbines to each other

[jedufa]

Good morning folks,

I am building a small wind farm which consists of 8 vertical axis turbines. Each turbine has different voltage output for a specific wind force. Voltages, in general, will oscillate between
0 and max 30V from what I have seen so far, tending in the 10-20V region in normal wind conditions. I intend to plug the system into my house electrical system for my household appliances and normal usage. I am at deciding which inverter i need and I am faced with the choice of combining the voltages of the turbines.

There are a few 1kw 12V inverters out there. I could combine the turbines in parallel (most common setup from what i recon). Or I could combine them in serie to increase the voltage and use a 1kw 24V or 48V inverter instead. I don't know what the best solution is between the two. I know it would let me use thinner cable, but the entire system is in close proximity to the electrical connections, so I am not sure if such an argument is very strong in my case. I also have heard that in parallel, the final voltage is driven by the smallest voltage producer of the group. If this is correct, a smaller turbine producing 7V would limit a bigger one producing 20V in the same wind at the same time.

So. Series or parallel? Is there another hidden option?
Thanks a lot,
JFD

[ghurd]

You need a battery.
Then the various voltages will never be more than the battery voltage.

You need blocking diodes, unless the PMAs are already rectified.
Then it does not matter if one is spinning to a higher or lower voltage than the others.

Series is not a good idea.
G-

[jedufa]

@ghurd

Thanks for the input. The turbines are rectified before being joined.
The system has no battery and I did not have the intention to add any.

Is there something to avoid if I go parallel, e.g. combining a low-voltage
turbine with higher-voltage ones? But I might not have the choice if that is
the case... .

JF

[ghurd]

You need a battery or the inverter WILL blow up.  For sure.  It is a fact.

There are a few inverters that can maybe take the wind power and feed it to the grid.
They are very expensive.
The rest of the required parts are also very expensive.
The act of connecting it can be very expensive.
So expensive it will not be worth it.
And I think they are all higher voltage input than you have to work with anyway, so it doesn't matter.
G-

[jedufa]

Thanks again G.
 
I have an overvoltage protection before the inverter and a fuse after the inverter.
If i plug the rectified DC of my turbines in parallel, where one generates 10V, the second one generates 12V and the third one generates 15V at a precise point in time, why would my rectifier blow up if it is rated for 9V-16V input?

Are you saying that I should use a battery as a buffer between the parallel turbines and the inverter?
Then, what is your solution to get the power from the wind farm to your electrical system?

Thanks,
JF

[ghurd]

Imagine this-
The open voltage of the turbines is 14V, which is fine for the inverter.
The inverter has a 100W load.
The load reduces the turbine voltage.
The inverter goes LVD....
The turbine voltage instantly goes back to 14V, the inverter turns on, the turbine voltage drops, the inverter goes LVD, the turbine voltage instantly goes back to 14V, the inverter turns on, the turbine voltage drops, the inverter goes LVD, etc etc etc.

2 problems.
1-  The load is useless because it is just flickering if it is incandescent bulbs, and it is burning itself up with surge currents if it is a motor.
2-  The caps in the inverter are experiencing huge amounts of current flowing in and out, which overheats them, and the inverter blows up.

[wooferhound]

Make sure that all the turbines are rectified.
Connect all the Positives and Negatives together. (parallel)
Hook them up to a battery.
Connect a Dump Load system to the battery to keep it from overcharging.
Connect your inverter to the Battery too.

Do not connect your inverter output to your existing house wiring, it would result in sparks, burning wires and a blown inverter. The output from the inverter should be to outlets on separate isolated circuits that are not related to the house wiring.

Here is a source for an inexpensive Dump Load system
http://www.ghurd.info/

Here is a basic diagram of the hookup . . .