Wind Farm Power Curve for Turbine Site Group

[Windfrosch]

Hallo WAsP Team,
I need to calculate a Wind Farm Power Curve only for a part of the whole wind farm, not for all of the existing turbines. But the wake effects of the other turbines to the turbines, which are from interest should be modelled. Is it possible?

Thank you very much!

Best regards,
Windfrosch

[Morten]

Hi Windfrosch,


WAsP does not support this directly, but as a work-around method you could try a modified power curve for the turbines you wish to exclude from the windfarm power curve. This modified power curve must have the usual Ct-coefficient curve but a close-to-zero power curve. Ideally that should be exactly zero power for all wind speeds, but then WAsP would fail to import the file, so better use tiny values instead.


The easiest way to modify the turbine power curve is to
- export to a WTG file,
- open the WTG file in the WAsP turbine editor,
- export to the old POW format
- open the POW file in an ASCII editor
- reduce the power scaling parameter (second parameter, third line), say from 1000 to 0.0001
- save the modified POW file
You now have a model for an incredibly inefficient turbine, producing almost no power but with the usual wake loss at the other turbines.


Now go back to the WAsP project, insert the modified POW file in the subgroup representing turbines you want to exclude from the windfarm power curve and recalculate. As a check you might compare the NetAEP of the turbines of interest to their NetAEP using the original WTG for all turbines. I got small deviations on the last digit, but hope that is OK.


Finally, when you have the special-purpose wind farm power curve, you should revert to the original WTG file for all turbines.


Cheers,
Morten

[Windfrosch]

Hello Morten,

thank you very much for your help. I tried your way and it works very well.

Best regards,
Windfrosch

[Duncan]

Hello,

I'm very happy to hear that Morten's clever workaround was what you needed, Windfrosch.

We have just made some changes to the wind farm in the soon-to-be-released WAsP 12.3, but there was no opportunity to implement support for your requirement. We will keep in mind for the future. It would be interesting to know if this is something that many users need.

Best wishes, Duncan.