Environmental Engineering Reference
In-Depth Information
1
1
1
0.8
0.8
0.8
0.6
0.6
0.6
EC1 EC2 EC3 EC4 EC5
EC1 EC2 EC3 EC4 EC5
EC1 EC2 EC3 EC4 EC5
1.1
1.1
1.1
1
1
1
0.9
0.9
0.9
0.8
0.8
0.8
EC1 EC2 EC3 EC4 EC5
EC1 EC2 EC3 EC4 EC5
EC1 EC2 EC3 EC4 EC5
M1
M2
M3
Fig. 11.15 Fault: actuator performance degradation. Normalized RMS (NRMS) of generator
power error, blade pitch rates, and platform motions
11.5.5 Actuator Stuck
Actuator stuck has dangerous effects on the turbine structure, and the angle at
which the blade seize plays a big roll in the total structural loading. The small
stuck angles leave the blade at the maximum aerodynamic loading, which increase
significantly the rotor imbalance, so the LSS and the tower torsional moments are
mostly affected, with DEL going up to 5 times compared to the faulty-free turbine
operating under the same condition. The fault also affects the faulty blade flap-
wise and edge-wise bending moments. For example, the stuck angle at 0 repre-
sents the maximum aerodynamic loading over the faulty blade. As the turbine
operates at EC1, the stuck angle will not increase the rotor imbalance as this angle
is close to the mean pitch angle for a fault-free turbine operating under the same
condition. The rotor aerodynamic loading will lose the balance as the faulty blade
is always at maximum aerodynamic loading with the increase of mean wind speed
in the full load region, while the faulty blade is still stuck at 0 and the other blades
are pitching following the set-point of the GSPI pitch controller. This will result
from one side to an increased root loading moment of the faulty blade, and from
the other side due to rotor imbalance, the LSS and tower torsional loading
moments are also increased as it is clear from Fig.
11.16
.
The generator power is also affected by this fault, with minimum generator
error RMS at EC1. The effect of this fault increases between EC2 and EC3 then it
reduces for EC4 and EC5, the increase in generator error is related to the increased
