1 kW turbine and Power One system?

[Paul Pavone]

I am installing a 1 kW turbine with a PMG gneerator and 220 Vac, 3 phase. I am using the Aurora Power One 7200 W WIB and 3.0 kW Inverter. The system will be grid tied. My question is what size dump load should I use? I have a 1500W, 75 ohm Milwaukee resistor that was given to me. Should that suffice?

[Paul Pavone]

Actual the resistor enclosure that was given to me was a Milwaukee with three 1500 w, 75 ohm resisters that were wired in parallel.

[Andy Rhody]

Can you tell us more about your turbine like the name, volts, RPM's etc? Do you have any photos of your setup? I also have the Power One 3Kw inverter and it works real sweet!

[Rob Beckers]

Paul, so rated output of 1kW is at 220V AC, 3 phase?
That would make just about 300V DC after rectifying. Three 75 Ohm resistors in parallel makes for 25 Ohm. Connecting 25 Ohm to a 300V source means the dump load draws 300^2 / 25 = 3,600 Watt.

That's below the capacity of the dump load resistors, the three of them would be able to handle 3 * 1,500 = 4,500 Watt together. So they won't burn up. That's good!

Loading up a 1kW turbine with 3,600 Watt (if that Voltage above is correct) will likely "put on the brakes" quite effectively. How well this works depends on a number of variables though. Also keep in mind that a dump load, for it to be effective, walks the fine line between putting enough load on the turbine to slow it down, vs. putting on a load just shy of burning up the alternator.

What dump load size is needed really varies for each model of wind turbine. Loading up with around 3x the rated power is not unusual though. Normally the manufacturer will have tested this to make sure that it works, and doesn't damage the alternator. If the manufacturer didn't provide a value for this you have just become your own R&D engineer.

-RoB-

[Paul Pavone]

Rob

I believe you nailed it. I designed a DAWT wind turbine and I'm doing a performance test at Intertek small wind facility in NY. The turbine has a PMG generator 1000 watt, 220 Vac, 3 phase. My electrical balancing system is a Power One WIB and 3.0 Inverter. The wind resource was 8 to 10 m/s and we were hitting 1158 watts. However, recently with the high winds the system failed. We shut it down. After the winds resided, we turned the system on and the generator (blades) did not move, like they were short circuited. So the I guess the dump load was too much. I need help with the correct size dump load and designing the corrrect electrical system as we are going much larger in kW size. Please feel free to call me or email.

[Cor van Houtum]

I am installing a 1 kW turbine with a PMG gneerator and 220 Vac, 3 phase. I am using the Aurora Power One 7200 W WIB and 3.0 kW Inverter. The system will be grid tied. My question is what size dump load should I use? I have a 1500W, 75 ohm Milwaukee resistor that was given to me. Should that suffice?

Hello Paul,
the Aurora windbox has no voltage regulation on the dump attack point
This wil kill the turbine when your inverter becomes off grid

your small turbine generator wil spin up and before it hits the 450 volts where the aurora box comes into dump,
the speed of the blades wil be so high that they fly away

you can use this box as a rectifier but complete it with a measurement relay that comes in
when a voltage of 300 is reached
So build your own dumpload round the box

kind regards
Cor

[Paul Pavone]

thank you. I was on site yesterday. The generator was fine. I am using a mercotac 335 slip ring/connector housed in the Kaydon swivel bearing. I believe it short circuited. I will take your suggestion and remove the dump load from the Power One rectifier. I will install the overvoltage schematic that Rob posts. My question is with the Omron K8AB-VS3, if the generator is a 220 Vac, should I use the 100-115 Vac or the 200-230 Vac? I see the connection is phase 1 and 2 only. An EE asked why I didn't have fuse protection for the voltage input (10A)? I will probably go to 16 AWG wire.

If the grid fails the Power One inverter is UL1741 so it shuts off. If the Omron monitor is 120 Vac plugged in it also shuts off. Execuse my ignorance, but does it still dump the power?

It is very difficult to find an EE or experienced wind turbine electrical personnel in western NY. Is anyone here interested in outsourcing their time and knowlege? And at what rate?

Thank you

[Rob Beckers]

Paul, you're in luck, giving out free advise is my loss-leader for the month... :blink1:

Either the 115V or the 230V version will work. I've always used the 115V one, but there's no reason why the 230V one would be any different.

You're also correct that the sensing lines should have a fuse in them, sized in accordance with their wire size. However, if that fuse blows it would be bad, as you would loose sensing and the the Omron will no longer see over-voltage! It's a bit like the reason there are no fuses in the 3-phase wind turbine wires; if one of those fuses blows your turbine would run away with no chance to stop it via a dump load.

The wiring diagram I posted has two options: One with and one without dump load. The version with dump load is fail-safe: When the power goes out the Omron will stop powering the contactor, and it will drop off, causing the turbine to switch over to dump load.

-RoB-