Using WasP for near ground studies

[Thierry]

Hello,

i would like to know if the wasp model is considered efficient in modeling AEP of near ground turbines.

I think about 12 m height or less (even 2 m).

Best regards.

[Mark Kelly]

Hello Thierry,
WAsP was indeed developed originally for turbines in the surface layer, so generally heights down to 10m (or less) are usually ok.
There are a few problems that arise when going below 10m:
1) there tend to be many more obstacles, which need to be individually modelled;
2) obstacles tend to induce more turbulence, which is not modelled by WAsP.
So approaching the ground, one has to rely on the obstacle model, which is designed for obstacles that are (appreciably) lower than hub height (or far enough away); this model gives wind speed reductions, but has quite a bit of uncertainty--particularly as the distance to obstacles decreases.

We also have had a side project with EMD for smaller turbines called WAsP Online, where one can use a web interface to do simplified WAsP calculations (http://www.mywindturbine.com ).

At any rate, I would exercise caution regarding any obstacles for small turbines, as well as considering what kind of turbine you are using (e.g. HAWT, with/out yaw drive).

with kind regards,

[Thierry]

Okay, thank you for your answer Mark.

Have a nice day.