10089_001.pdf - Load set calculation - ECN
10089_001.pdf - Load set calculation - ECN
10089_001.pdf - Load set calculation - ECN
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<strong>Load</strong> <strong>set</strong> <strong>calculation</strong> DOWEC 6MW H. Efdé<br />
Plots in Appendix I show the behaviour of several towers.<br />
5.4 Turbine control.<br />
Three alternative controls are modelled (ref. [11]) and calculated, a High Tip Speed (HTS), Low Tip<br />
Speed (LTS) and a Peak Shave (PS) control. The HTS turbine runs with a nominal speed of 12.58<br />
rpm at Vr=11.7 m/s. The LTS turbine runs with 10.36 rpm at Vr=12.3 m/s.<br />
The first eigenfrequency of the tower of the HTS control turbine is increased from 0.242 to 0.257 Hz.<br />
This will prevent undesired excitations due to the higher nominal speed.<br />
The PS control does not change the rpm, but limits the maximum axial force on the hub in this case<br />
by opening the blade pitch 2 degrees at Vr. The design of the PS control is based on ref. [15].<br />
The results of the load case <strong>calculation</strong>s can be found on CD C45.04/01.03/03. The extreme and<br />
fatigue tables can be found in Appendix F as well.<br />
5.4.1 Cost of energy.<br />
For the cost of energy of the HTS and LTS control the average gearbox torque and the annual<br />
production is calculated. The average gearbox torque is determined by calculating the average<br />
torque of the generator power curve from the Phatas input file “DowecHTS.inp” and “DowecLTS.inp”.<br />
Phatas IV is used to create a PV curve of the HTS and LTS control. Consequently with the Phatas<br />
post processing program “Eprod” the annual production is calculated. The results are presented in<br />
the table below.<br />
Table 15: HTS and LTS control, cost of energy.<br />
parameter baseline<br />
High Tip<br />
Speed<br />
control<br />
relative<br />
turbine<br />
costs<br />
Low Tip<br />
Speed<br />
control<br />
relative<br />
turbine<br />
costs<br />
Blade kNm % % % %<br />
Myb[1]-p[01] 18006.00 2.15 0.03 -16.28 -0.24<br />
1Hz-Mxb[2]-p[01] 6740.51 0.72 0.01 -8.45 -0.13<br />
gearbox<br />
Mxn mean 30400.28 -5.34 -0.20 3.45 0.13<br />
tower<br />
Myt[01] -281560.00 4.94 0.24 -17.98 -0.86<br />
1Hz-Myt[02] 6372.64 4.86 0.16 -9.81 -0.31<br />
total 0.24 total -1.42<br />
annual production baseline HTS change (%) LTS change (%)<br />
Gwh 25.4014 25.5353 0.53 24.656 -2.93<br />
HTS control, change in cost of energy (%) - 0.29<br />
LTS control, change in cost of energy (%) 1.47<br />
R45.04/01.03/03 Stentec, 3-1-03 page 18
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