Error due to differences in densities of WT curves and Reference sites

[seenu]

The wind turbine data sheets do not have the density used for the power curves. So I presumed it to be 1.225 kg/m3 as most turbines data sheets are estimated using that density.

However, the density of my site is 1.17 kg/m3.

WAsP says that it cannot calculate AEP due to the density differences when I use two different densities.


(1) Changing the WTG density to 1.17 kg/m3 is an option to estimate AEP. But that power curves were not estimated at that density. This would also lead to overestimation of AEP.


(2) Using 1.225kg/m3 for reference site is another method, which would again overestimate AEP at the reference sit.

Is there any methods to solve this problem?

Thank you

[Andreas]

One option is to use WAsP 12 where you can select two different density correction policies in the WTG hierarchy member - that will automatically be adopted across all turbine sites. The default policy is to use interpolation as described in IEC standard 61400-12-1. The other option is to use Svenningsen extrapolation method (adjusted IEC extrapolation method, improved to match turbine control) described in the abstract/poster “Proposal of an Improved Power Curve Correction”, presented by Lasse Svenningsen (EMD International A/S) at the European Wind Energy Conference & Exhibition 2010 in Warsaw.

WAsP 11 users do not have this option, but it is recommended to obtain a site-specific power curve from the manufacturer or investigate the two above references

[seenu]

Thank you.