Klim, Denmark Case study. - EMD

Klim, Denmark, CASE - 01
1600
1500
Long term corrected production (MWh/year)
Calculated yield, WDC 0.075
1400
MWh/WTG/year
1300
1200
1100
1000
MEAN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35
WTG number
Figure 10 The "first shot" calculation simply hit the actual value. Calculation is 2 % lower than
actual, before power curve correction. Power curve corrected with 2% add on to calculation,
there will be exact match. So for the result as a whole the match cannot be expected better.
Also the variations within the WTGs seem fairly well.
Variation of WDC –Standard DK wind statistic
100
Klim Fjordholme, Denmark
35 Vestas 600 kW, based on 32 months production
95
PARK efficiency (%)
90
85
80
75
Actual Park efficiency based on assumed PARK efficiency.: 89%
Calc Park eff. WDC 0,075 (Standard)
Calc Park eff. WDC 0,04 (less turbulent)
Calc Park eff. WDC 0,1 (more turbulent)
70
MEAN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35
WTG-number
Figure 11 Varying the Wake Decay Constant (WDC) gives quite large changes. With WDC = 0.1
the PARK efficiency increase from 0.885 to 0.905 – 2 %. But at 0.04, which normally is
recommended for offshore, the park efficiency decrease to 0.845, which is 4% lower than
standard. From the figure above, it is difficult clearly to see what the correct value will be. We
therefore continue with a shorter, but more reliable data period.
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