Environmental Engineering Reference
In-Depth Information
Fig. 12.10 One- and three-
per-revolution frequencies of
the reference wind turbine
Table 12.5 Wind field sim-
ulation parameters
Number grid points
31 9 31
Grid dimension
145 9 145 m
Simulation time
1,030 s
Time step
0.05 s
Turbulence model
Kaimal
Turbulence type
Normal turbulence
model
Wind profile type
Power law
Height of the reference wind speed
90 m
Mean wind speeds
3-25 m/s
The wind turbine is assumed to be in operation and system controls for variable
speed and blade pitch are active. The simulations are carried out for normal wind
conditions with a normal wind profile model as described in IEC 61400-1 [
19
].
The relevant simulation parameters of the wind field are listed in Table
12.5
.
12.4.3 Simulation Results
12.4.3.1 Onshore Reference Wind Turbine with a Tuned Mass
Damper
The first calculations are carried out by means of the onshore version of the
reference wind turbine, which is assumed to be connected rigidly to the ground. In
order to mitigate the first fore-aft tower bending mode vibrations, the TMD is
tuned to the fundamental frequency of 0.324 Hz. The parameters of the turbine and
TMD are summarized in Table
12.6
.
Figure
12.11
compares the time histories of tower deflection with and without
TMD for the cut-in, rated, and cut-out wind speeds. The frequency spectra of the
tower responses are shown in Fig.
12.12
. Hereby, resonant tower vibrations occur
especially at the cut-in wind speed 3 m/s. This can be seen also in the frequency
