Environmental Engineering Reference
In-Depth Information
Statisti cal analysis of the Generator Sp eed
Statist ical analysis of the Electric Po wer
1400
6000
max
max
mean
mean
1200
5000
1000
4000
m
i
m
i
800
3000
600
2000
C1
C2
C3
400
1000
200
0
5
10
15
20
25
5
10
15
20
25
Wind Speed (m/s)
Wind Speed (m/s)
Fig. 5.25
Statistical analysis
reduced, but the pitch actuator bandwidth of the 'Upwind' model is only 1 Hz. The
activity of the tower base moment in x is reduced with the C4 control strategy at
the tower side-to-side first frequency, and the stationary hub moment in z is hardly
mitigated at small frequencies due to the correct alignment of the rotor plane with
IPC.
Figure 5.25 shows an statistical analysis of the regulated variables of generator
speed and electric power. The maximum, minimum and mean values of these
signals in different power production wind simulations are represented in
Fig. 5.25 . The regulation of the generator speed is better using C3 control scheme
because the maximum and minimum values are closer to the nominal generator
speed than with other strategies. Inherently, the regulation of the electric power is
also better using C3 in spite of the difference in the generator torque control loop.
Table 5.4 represents the fatigue analysis with the four control schemes. C1is
considered as the reference to calculate the percentage of fatigue load reduction in
different moments in the wind turbine components with the other control strate-
gies. The m constant of material is 3 for the tower, m is 9 for the hub and for the
yaw system and m is 12 for the blades. The inclusion of the generator torque
contribution using the H ? torque controller in C2 reduces the fatigue load in the
tower base moment in x axis in 11.9 % without important load increase in other
components. The improvement in the generator speed regulation using C3 does not
involve enhanced profits in the fatigue load analysis. On the other hand, the IPC
based feedback control loop included in the C4 control strategy considerably
affects to the fatigue loads. The fatigue loads are reduced in 7.5, 5.9, 5.3 and 5.5 %
in the blade root moment in y axis, stationary hub moment in z axis and yaw
bearing x and y moments respectively compared to the C2 control scheme. The
load reduction in the tower base moment in x axis due to the reduction of the wind
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