windspot "hangs"on 46 volts with aurora

[Cor van Houtum]

Hello ,

I have found that the windspot turbine has a dead spot in some winds
When connected to a 6kw power-one inverter.
(did not test it with other aurora inverters yet)

The dead spot occurs when there is not much wind.
Situation :

Low wind , the turbine spins up from start
The inverter is completely dead (normal situation)
Inverter gets awake and starts to produce a little power
Now the wind goes less hard
The voltage of dc-in drops to 46 volts
IT SEEMS THAT THE WINDSPOT HANGS ON 46 VOLTS AND TURNS SLOW
The inverter is still on and is showing dc input 46 volts – output watts 0

Here the situation can stay hanging for hours with no output
when there are no windgusts that kick the turbine over this spot

By disconnecting the inverter from the grid and wait untill the then free spinning windspot reaches a voltage from above 150 volts
Then connect the grid again to the inverter , the windspot will stay ABOVE THE DEADSPOT and will continue to produce energy

Solution to this problem :

In the inverter setting put VSTART 1+2 on 150 volt
And then put the setting UV-PROT-TIME to 1 second

Now the inverter will go dead when the voltage is not enough
The windspot is then freewheeling and will go up to more then 150 volt easy.
Then the inverter is connecting again to the grid

It is like pushing the car downhill and then put it in gear when there is enough power and speed

This works and I found that the production will go up drastically when there are days with low wind.

The programmed power curve in the aurora inverter is not influencing this problem
It seems that the aurora has an internal power point on 46 volts where it needs 0,5 Amps to start again
This is just enough power to let the turbine run against this small hill and stays hanging there
This happens with small wind speeds.

Kind regards

Cor van Houtum
Draaistroom Nederland

[Rob Beckers]

Cor, to add a little bit more to this: The Power-One wind inverters have a (minor) issue in that their DC input will "hang" at around 50 - 65 Volt even when there is nothing coming in. The cause seems to be feedback from the grid side, somehow creating sufficient DC voltage to keep the inverter "on" if Vstart is set below (around) 70 Volt. This is not specific to the WindSpot turbine.

The solution is to add some bleed resisters to the DC input of the inverter; around 100 kOhm / 5 Watt seems to do the trick just fine.

The other solution is of course to up the Vstart Voltage, allowing the inverter to switch off above that stray Voltage, usually 70 Volt or more will do that.

I understand that in case of the WindSpot this is half the story, and you also have the issue that at 50-or-so Volt the turbine is just loaded enough and just stalled enough that it won't spin up to get out of stall.

Regarding the UV-Prot time, this is how long the inverter will continue to be switched "on" after the Voltage dips below Vstart, I would suggest to set that to something around 300 seconds. Certainly not at just a few seconds! Settings that low will cause the inverter to switch on/off frequently in low and variable winds, which is undesirable (not great for the turbine as it will spin up to reach max RPM until the inverter is back on and loading it, and not good from a production perspective because the inverter will spend significant time doing the grid-tie handshake and switch back on each time it does off, making you loose out on energy production).

-RoB-

[Andy Rhody]

For my Turbine we used the Solacity wind controller and I had the same issue with the "stray" voltage not allowing the inverter to shut down so I add the 100 kOhm resistor. In fact I added two. It solved the problem. I put the resistor in the controller on the DC output going to the inverter.

Here's the resistor in the middle of the controller.

http://i41.photobucket.com/albums/e295/andy47bottles/Science/SANY1575_zps10aa4aca.jpg (http://s41.photobucket.com/user/andy47bottles/media/Science/SANY1575_zps10aa4aca.jpg.html)

Here's a close-up.

http://i41.photobucket.com/albums/e295/andy47bottles/Science/SANY1576_zpsb4313fbe.jpg (http://s41.photobucket.com/user/andy47bottles/media/Science/SANY1576_zpsb4313fbe.jpg.html)

[Shaun Burgess]

hi all i have a 22k 17watt across the dc input , seems to work just fine