10089_001.pdf - Load set calculation - ECN

Load set calculation DOWEC 6MW H. Efdé
• tt+5-5, girders 0.5 o rotated, at root girder suction side 0.5m forward and girder pressure
side 0.5 m aft.
• tt-5+5, girders 0.5 o rotated, at root girder suction side 0.5m to aft and girder pressure side
0.5 m forward.
The modified turbine models are tested with load cases 008, 012, 018 and 024, 231 and 234. Load
case 231 is a stochastic windspeed of 12 m/s with –20 o yaw, 234 a stochastic windspeed of 25 m/s
with –20 o yaw.
To prevent interference of the blades with the turbine, the dynamic behaviour of the tower has been
switched off. Also the baseline loadcases have been recalculated with tower dynamics off.
This explains the difference in baseline loads in the table below, compared to the other
variations.The results of the simulations are stored on CD C45.04/01.03/03 . The extreme and
fatigue tables can be found in Appendix D as well.
5.2.1 Cost of energy.
The calculation of the cost of energy can only be based on the fatigue and extreme loads of the
blades. Gearbox loads, tower loads and energy production are not taken into account because the
aerodynamics of the blades are not changed and the tower dynamics are off. Therefore it is
assumed that these parameters have not changed.
Based on the changed loads the results in relative turbine costs are as follows:
Table 13: Structural pitch, cost of energy.
blade parameter baseline tt-5+5
relative
turbine
costs tr+5-5
relative
turbine
costs tt+5
relative
turbine
costs tt+5-5
relative
turbine
costs
kNm % % % % % % % %
Myb[1]-p[01] 15535.00 0.70 0.01 3.40 0.05 0.70 0.01 3.70 0.06
1Hz-Mxb[1]-p[01] 8327.10 1.05 0.02 -0.60 -0.01 0.90 0.01 -12.00 -0.18
total 0.03 total 0.04 total 0.02 total -0.12
The influence of the design variations on the cost of energy is similar to the relative turbine costs.
R45.04/01.03/03 Stentec, 3-1-03 page 16