10089_001.pdf - Load set calculation - ECN

Load set calculation DOWEC 6MW H. Efdé
The standard load cases apply to a rotorspeed of 11.84 rpm, the LTS (Low Tip Speed) load cases
10.36 rpm and the HTS (High Tip Speed) loadcases to 12.58 rpm. For this Low Lambda analysis
load case 027LL was generated to assess the fatigue damage of a LTS turbine at a stochastic
windspeed of 27 m/s (wished rotorspeed at 10.36 rpm).
The occurrence of the load case is based on a Rayleigh distribution with a Vm of 9.2 m/s. The Pmean
is the average generator power of the load case and is used to calculate the yearly production.
The results of the load case calculations can be found on CD C45.04/01.03/03. The 1Hz equivalent
fatigue tables can be found in Appendix H as well.
5.6.1 Cost of energy.
The blade- and tower parameters and the annual production are taken into account for the
calculation of the cost of energy. The annual production is calculated by ADAP using the occurance
and mean power from table 18. The average gearbox torque could not be used, since the
rotorspeed-shaft torque table differs per loadcase. Also extreme values are not available because
the loadsets consisted only of fatigue loadcases. The results are presented in the table below.
Table 19: Cost of energy Low Lambda control variations.
Low
Low
Low
Low
Lambda 1 change in Low Lambda change in Lambda 3 change in Lambda 4 change in Lambda 5 change in
100% loadcase change cost 2 change cost change cost change cost change cost
blade kNm % % % % % % % % % %
Myb[i]-p[01] -18006.00 Eog50-12 n.a. n.a. n.a. n.a. n.a.
1Hz-Mxb[i]-p[01] 4483.82 all -1.72 -0.03 -0.71 -0.01 1.46 0.02 1.79 0.03 0.89 0.01
gearbox
Mxn mean n.a. n.a. n.a. n.a. n.a.
tower
Myt[01] -281560.00 GrEog1Voc n.a. n.a. n.a. n.a. n.a.
1Hz-Myt[02] 2558.84 all -4.33 -0.14 -1.83 -0.06 0.73 0.02 3.95 0.13 0.32 0.01
total -0.16 total -0.07 total 0.05 total 0.15 total 0.02
annual production baseline LL1 change (%) LL2 change (%) LL3 change (%) LL4 change (%) LL5 change (%)
MWh 3532.3 3511.4 -0.59 3528.4 -0.11 3429.4 -2.91 3422.4 -3.11 3427 -2.98
LL1 loadset, influence on cost of energy 0.42
LL2 loadset, influence on cost of energy 0.04
LL3 loadset, influence on cost of energy 2.76
LL4 loadset, influence on cost of energy 3.17
LL5 loadset, influence on cost of energy 2.92
Based on the simplified Low Lambda load sets and the cost of energy model, it can be concluded
that only LL1 has a reasonable decrease in fatigue damage. But because the annual production is
lower, the cost of energy increases. LL3 to LL5 even cause more fatigue damage than the baseline
while production is lower than the baseline.
R45.04/01.03/03 Stentec, 3-1-03 page 22