Klim, Denmark Case study. - EMD

Klim, Denmark, CASE - 01
If we turn the visualisation of the rows, and look at the northwestern 4 WTGs as row
1 etc. the pattern look so.
100
95
90
PARK efficiency (%)
85
80
75
Actual Park efficiency based on assumed PARK efficiency.: 88%
Calculated yield, WDC 0.075 Ct-V44
Calculated yield, WDC 0.075, Ct-V52
1 2 3 4 5 6 7 8 9 10
70
10 20 30 35 9 19 29 34 8 18 28 33 7 17 27 32 6 16 26 31 5 15 25 4 14 24 3 13 23 2 12 22 1 11 21
WTG number
Figure 15 Here it is even clearer, that the back rows (assumed prevailing West-northwest wind)
follow the most reducing Ct curve very well. Comparing to the below shown comparison by
calculating with different WDC, we have to admit that adjusting the Ct value to a more reducing
value gives a better match to actual production for the 5 eastern rows that adjusting the WDC.
So all in all, a combination of adjustments on WDC and Ct might give better match
between actual and calculated values for the individual WTGs. But we still believe,
that it is the calculation model, which has to be adjusted.
Additionally analyses – Windfarmer Eddy Viscosity wake model
comparison
Finally, we have got a calculation using the Windfarmer tool from Garrad Hassan,
which can operate with more different models, where the “Eddy Viscosity” model is
said to be more precise. This we have tested on the Klim case with the 1998 data
selection.
Energi- og Miljødata, Niels Jernesvej 10, DK-9220 Aalborg O – Tel: +45 9635 4444, Fax: +45 9635 4446, Mail:
emd@emd.dk, Web: www.emd.dk - 14 -