Environmental Engineering Reference
In-Depth Information
Table 5.4
Fatigue load analysis
m
C1
C2
C3
C4
Blade MFlap
12
100
98.6
100
102.1
Blade MEdge
12
100
99.5
100
100.1
Blade root Mx
12
99.9
101.0
100
100.0
Blade root My
12
98.8
91.3
100
98.9
Blade root Mz
12
98.3
99.0
100
101.0
Stationary hub Mx
9
100
99.0
100
99.8
Stationary hub My
9
99.2
92.8
100
99.6
Stationary hub Mz
9
99.9
94.0
100
101.0
Yaw bearing Mx
9
101.3
99.2
100
98.4
Yaw bearing My
9
99.2
93.9
100
99.3
Yaw bearing Mz
9
99.5
94.0
100
99.6
Tower base Mx
3
88.1
85.2
100
86.2
Tower base My
3
95.0
97
100
95.2
Tower base Mz
3
99.9
108.8
100
100.0
effect in the tower side-to-side first mode is a 2.9 % better using the IPC in C4 than
with the generator torque control loop in C2. The control effort to align the rotor
plane developed by the IPC of the C4 control scheme involves a load increment of
8.9 % in the tower base moment in z axis.
Lastly, Tables
5.5
and
5.6
show the extreme load analyses using the four
control schemes. These analyses are very influenced by the activation and deac-
tivation of the controllers, mainly of the IPC, when the wind turbine arrives to
work in the above rated zone, so the results using IPC in C4 control scheme could
be improved using better start-up strategies of the control system.
In the extreme DLC1.6 load case analysis, the blade root edgewise moment is
hardly reduced due to the faster response of the collective pitch robust controller to
regulate the generator speed. This rapidity also reduces other loads in blades, hub,
yaw and tower. The C3 control strategy does not present important improvements
compared to the C2 (only the blade root flapwise moment is reduced). On the other
hand, the activation of the IPC in C4 control strategy involves important load
reduction of 28.72 and 22.8 % compared to C2 in the DLC1.6 case in stationary
hub moment in y axis and in the tower base moment in x axis respectively. Also,
the C4 control strategy activation involves load increments in blade root moment
in x axis, yaw bearing moment in z axis and tower base moment in z axis due to the
extra-effort to align the rotor plane with the IPC.
The extreme load DLC1.9 analysis present important extreme load reductions
in the x axis of the moments analyzed in Table
5.5
using the C2 control strategy
compared to the C1. Also, the activation of the C3 control scheme with the
collective pitch gain scheduled robust control improves the regulation of the
